U.S. patent application number 15/488927 was filed with the patent office on 2017-11-23 for drilling fluid additive composition and pseudo oil-based drilling fluid suitable for horizontal shale gas wells.
This patent application is currently assigned to CHINA UNIVERSITY OF PETROLEUM (BEIJING). The applicant listed for this patent is CHINA UNIVERSITY OF PETROLEUM (BEIJING). Invention is credited to Junbin CHEN, Deli GAO, Liexiang HAN, Yinbo HE, Guancheng JIANG, Fan LIU, Guangchang MA, Wei OU'YANG, Gang QU, Haifang SUN, Xianzhu WU, Jienian YAN, Lili YANG, Xianmin ZHANG, Li ZHAO.
Application Number | 20170335163 15/488927 |
Document ID | / |
Family ID | 60329501 |
Filed Date | 2017-11-23 |
United States Patent
Application |
20170335163 |
Kind Code |
A1 |
JIANG; Guancheng ; et
al. |
November 23, 2017 |
DRILLING FLUID ADDITIVE COMPOSITION AND PSEUDO OIL-BASED DRILLING
FLUID SUITABLE FOR HORIZONTAL SHALE GAS WELLS
Abstract
The present invention relates to the well drilling field in
petrochemical industry, and discloses a drilling fluid additive
composition comprising a nano-plugging agent, a bionic wall bracing
agent, a bionic shale inhibitor, an emulsifier, and an amphiphobic
wettability reversal agent, wherein, the nano-plugging agent is
modified silicon dioxide nano-particle, and its modifying group
includes a modifying copolymer chain; the bionic wall bracing agent
is carboxymethyl chitosan with a dopamine-derived group grafted on
its main chain; the bionic shale inhibitor is composed of
structural units of arginine and structural units of lysine; and
the amphiphobic wettability reversal agent is a dual-cation
fluorocarbon surfactant. The present invention further provides a
pseudo oil-based drilling fluid suitable for horizontal shale gas
wells containing the above composition. When the water-based
drilling fluid contains the drilling fluid additive composition
provided in the present invention, the water-based drilling fluid
would have high temperature-resistance, high plugging and high
inhibition performance, is environment friendly, especially have
high density, and is especially suitable for horizontal shale gas
well mining.
Inventors: |
JIANG; Guancheng; (Beijing,
CN) ; ZHANG; Xianmin; (Beijing, CN) ; HE;
Yinbo; (Beijing, CN) ; GAO; Deli; (Beijing,
CN) ; WU; Xianzhu; (Beijing, CN) ; YANG;
Lili; (Beijing, CN) ; MA; Guangchang;
(Beijing, CN) ; QU; Gang; (Beijing, CN) ;
ZHAO; Li; (Beijing, CN) ; LIU; Fan; (Beijing,
CN) ; SUN; Haifang; (Beijing, CN) ; OU'YANG;
Wei; (Beijing, CN) ; YAN; Jienian; (Beijing,
CN) ; CHEN; Junbin; (Beijing, CN) ; HAN;
Liexiang; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CHINA UNIVERSITY OF PETROLEUM (BEIJING) |
Beijing |
|
CN |
|
|
Assignee: |
CHINA UNIVERSITY OF PETROLEUM
(BEIJING)
Beijing
CN
|
Family ID: |
60329501 |
Appl. No.: |
15/488927 |
Filed: |
April 17, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/12 20130101; C09K
8/035 20130101; C09K 2208/12 20130101; C09K 2208/10 20130101 |
International
Class: |
C09K 8/12 20060101
C09K008/12; C09K 8/035 20060101 C09K008/035 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 2016 |
CN |
201610341613.0 |
Jan 18, 2017 |
CN |
201710038133.1 |
Claims
1. A drilling fluid additive composition comprising a nano-plugging
agent, a bionic wall bracing agent, a bionic shale inhibitor, an
emulsifier, and an amphiphobic wettability reversal agent, wherein
the nano-plugging agent is a modified silicon dioxide nano-particle
including a modifying group, the modifying group on the modified
silicon dioxide nano-particle includes a modifying copolymer chain,
and the structural units in the modifying copolymer chains are
provided by one or more monomers represented by formula (1) and one
or more monomers represented by formula (2): ##STR00035## wherein
one of R.sup.6-R.sup.10 is -L'-SO.sub.3H and the remaining
R.sup.6-R.sup.10 are independently selected from H, --OH, halogen,
and C1-C10 alkyl; L, L' and L'' are independently selected from
C0-C10 alkylene; wherein the bionic wall bracing agent is
carboxymethyl chitosan with a dopamine-derived group represented by
the following formula (I-1) grafted on its main chain: ##STR00036##
wherein the bionic shale inhibitor is composed of structural units
represented by formula (3) and structural units represented by
formula (4): ##STR00037## the molar ratio of the structural units
represented by formula (3) to the structural units represented by
formula (4) is 0.2-6:1, and the weight-average molecular weight of
the bionic shale inhibitor is 800-4,000 g/mol; wherein the
emulsifier is one or more compounds represented by formula (i):
##STR00038## in formula (i), each of the two R.sub.11 groups is
independently selected from C14-C30 alkyl optionally substituted by
group Y and C14-C30 unsaturated alkyl with carbon-carbon double
bonds optionally substituted by group Y, and the group Y is
independently selected from the groups represented by the following
formulae: ##STR00039## n' is an integer within a range of 1-8;
wherein n' X'-es are independently selected from H and
--C(O)--R.sub.21, and at least one X' is --C(O)--R.sub.21, R.sub.21
is selected from carboxyl, C1-C6 alkyl, C3-C8 cycloalkyl, C1-C6
alkyl substituted by carboxyl, C3-C8 cycloalkyl substituted by
carboxyl, C3-C8 cycloalkyl substituted by carboxyl and C1-C4 alkyl,
C2-C6 unsaturated alkyl with a carbon-carbon double bond, C3-C8
unsaturated cycloalkyl with a carbon-carbon double bond, C2-C6
unsaturated alkyl with a carbon-carbon double bond substituted by
carboxyl, and C3-C8 unsaturated cycloalkyl with a carbon-carbon
double bond substituted by carboxyl and C1-C4 alkyl; and wherein
the amphiphobic wettability reversal agent is a dual-cation
fluorocarbon surfactant of which the cation part is represented by
the following formula (a): ##STR00040## wherein, each R.sup.1 is
independently selected from C1-C6 alkyl, each R.sup.2 is
independently selected from H and C1-C6 alkyl, each R.sup.3 is
independently selected from C1-C10 alkylene, each n'' is
independently 3-15, and m is 1-10.
2. The composition according to claim 1, wherein the weight ratio
of the nano-plugging agent to the bionic wall bracing agent to the
bionic shale inhibitor to the emulsifier to the amphiphobic
wettability reversal agent is 100:20-500:20-500:20-500:5-100.
3. The composition according to claim 2, wherein the weight ratio
of the nano-plugging agent to the bionic wall bracing agent to the
bionic shale inhibitor to the emulsifier to the amphiphobic
wettability reversal agent is 100:30-400:30-400:30-300:10-50.
4. The composition according to claim 1, wherein the structural
units in the modifying copolymer chain is composed of one or more
of structural units represented by the following formula (1-a) and
one or more of structural units represented by the following
formula (2-a): ##STR00041##
5. The composition according to claim 1, wherein one of
R.sup.6-R.sup.10 is -L''-SO.sub.3H, and the rest of
R.sup.6-R.sup.10 are independently selected from H, and C1-C6
alkyl; L, L' and L'' are independently selected from C0-C6
alkylene.
6. The composition according to claim 5, wherein one of
R.sup.6-R.sup.10 is -L''-SO.sub.3H, and the rest of
R.sup.6-R.sup.10 are independently selected from H, and C1-C4
alkyl; L, L' and L'' are independently selected from C0-C4
alkylene.
7. The composition according to claim 6, wherein one of
R.sup.6-R.sup.10 is -L''-SO.sub.3H, and the rest of
R.sup.6-R.sup.10 are independently selected from H, methyl, ethyl,
propyl and butyl; L' and L'' are independently selected from C0
alkylene, --CH.sub.2--, --CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--CH.sub.2--, --CH(CH.sub.3)--CH.sub.2--,
--C(CH.sub.3).sub.2--CH.sub.2--, --CH.sub.2--C(CH.sub.3).sub.2--
and --CH.sub.2--CHCH.sub.3--CH.sub.2--; L is --CH.sub.2--,
--CH.sub.2--CH.sub.2--, --CH.sub.2--CH.sub.2--CH.sub.2--,
--CH(CH.sub.3)--CH.sub.2--, --C(CH.sub.3).sub.2--CH.sub.2--,
--CH.sub.2--C(CH.sub.3).sub.2-- or
--CH.sub.2--CHCH.sub.3--CH.sub.2--.
8. The composition according to claim 5, wherein in the modifying
copolymer chain, the molar ratio of the structural units provided
by the monomers represented by formula (1) to the structural units
provided by the monomers represented by formula (2) is 1:0.5-5; the
weight-average molecular weight of the modifying copolymer chain is
100,000-2,500,000 g/mol.
9. The composition according to claim 8, wherein in the modifying
copolymer chain, the molar ratio of the structural units provided
by the monomers represented by formula (1) to the structural units
provided by the monomers represented by formula (2) is 1:1-2; the
weight-average molecular weight of the modifying copolymer chain is
300,000-1,800,000 g/mol.
10. The composition according to claim 8, wherein based on the
total weight of the modified silicon dioxide nano-particle, the
content of the modifying copolymer chain is 60 wt. % or higher; the
particle diameter of the modified silicon dioxide nano-particle is
3-30 nm.
11. The composition according to claim 1, wherein the bionic wall
bracing agent contains structural units represented by the
following formula (I): ##STR00042## fn formula (I), R.sub.1 is H,
##STR00043## R.sub.2 is H, ##STR00044## and at least one of R.sub.1
and R.sub.2 is ##STR00045## n is an integer equal to or greater
than 1, each of the n R.sub.5 groups is H or the dopamine-derived
group respectively and independently, and at least one of the n
R.sub.5 groups is the dopamine-derived group, R.sub.4 is H or
C.sub.1-C.sub.10 alkyl, R''' is H, --CH.sub.2COOR.sub.3' or
--CH.sub.2COOR.sub.3, and R.sub.1 and R''' are not H at the same
time, R.sub.3' is H or alkali metal, and R.sub.3 is the
dopamine-derived group.
12. The composition according to claim 1, wherein in formula (i),
each of the two R.sub.11 groups is independently selected from
C14-C20 alkyl optionally substituted by group Y and C14-C20
unsaturated alkyl with carbon-carbon double bonds optionally
substituted by group Y; n' is an integer within a range of 1-6;
R.sub.21 is selected from carboxyl, C1-C4 alkyl, C4-C6 cycloalkyl,
C1-C4 alkyl substituted by carboxyl, C4-C6 cycloalkyl substituted
by carboxyl, C4-C6 cycloalkyl substituted by carboxyl and methyl,
C2-C4 unsaturated alkyl with a carbon-carbon double bond, C4-C6
unsaturated cycloalkyl with a carbon-carbon double bond, C2-C4
unsaturated alkyl with a carbon-carbon double bond substituted by
carboxyl, and C4-C7 unsaturated cycloalkyl with a carbon-carbon
double bond substituted by carboxyl and methyl.
13. The composition according to claim 12, wherein in formula (i),
each of the two R.sub.11 groups is independently selected from
C15-C18 alkyl optionally substituted by group Y and C15-C18
unsaturated alkyl with carbon-carbon double bonds optionally
substituted by group Y; n' is an integer in a range of 1-4.
14. The composition according to claim 1, wherein in formula (a),
each R.sup.1 is independently selected from C1-C4 alkyl, each
R.sup.2 is independently selected from H and C1-C4 alkyl, each
R.sup.3 is independently selected from C2-C8 alkylene, each n'' is
independently selected from integers within a range of 4-10, and m
is selected from integers within a range of 2-8.
15. The composition according to claim 14, wherein in formula (a),
each R.sup.1 is independently selected from methyl, ethyl,
n-propyl, isopropyl, and n-butyl, each R.sup.2 is independently
selected from H, methyl, ethyl, n-propyl, isopropyl, and n-butyl,
each R.sup.3 is independently selected from --CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--CH.sub.2--, --CH(CH.sub.3)--CH.sub.2--,
--CH.sub.2--CH(CH.sub.3)--,
--CH.sub.2--(CH.sub.2).sub.2--CH.sub.2--,
--CH.sub.2--(CH.sub.2).sub.3--CH.sub.2--, and
--CH.sub.2--(CH.sub.2).sub.4--CH.sub.2--, each n'' is independently
selected from 4, 5, 6, 7 and 8, and m is selected from 3, 4, 5 or
6.
16. The composition according to claim 1, wherein the cation part
shown in formula (a) is one of the following cations: formula
(a-1): in formula (a), each R.sup.1 is methyl, each R.sup.2 is H,
each R.sup.3 is --CH.sub.2--CH.sub.2--CH.sub.2--, each n'' is 4,
and m is 4; formula (a-2): in formula (a), each R.sup.1 is methyl,
each R.sup.2 is H, each R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, each n'' is 6, and m is 4;
formula (a-3): in formula (a), each R.sup.1 is methyl, each R.sup.2
is H, each R.sup.3 is --CH.sub.2--CH.sub.2--CH.sub.2--, each n'' is
8, and m is 4; formula (a-4): in formula (a), each R.sup.1 is
methyl, each R.sup.2 is H, each R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, each n'' is 4, and m is 6.
17. A water-based drilling fluid containing the additive
composition according to claim 1.
18. The drilling fluid according to claim 17, wherein with respect
to 100 pbw water in the drilling fluid, the content of the additive
composition is 20 pbw or lower.
19. The drilling fluid according to claim 18, wherein the density
of the drilling fluid is 2.3 g/m.sup.3 or higher.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priorities to Chinese Application
No. 201610341613.0, filed on May 20, 2016, entitled "Drilling Fluid
Additive Composition and Pseudo Oil-Based Drilling Fluid Suitable
for Horizontal Shale Gas Wells", and Chinese Application No.
201710038133.1, filed on Jan. 18, 2017, entitled "Dual-cation
Fluorocarbon Surfactant and Preparation Method thereof, and Its Use
As Amphiphobic Wettability Reversal Agent and Drilling Fluid and
Its Use", which are specifically and entirely incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the well drilling field in
petrochemical industry, in particular to a drilling fluid additive
composition and pseudo oil-based drilling fluid suitable for
horizontal shale gas wells.
BACKGROUND OF THE INVENTION
[0003] As energy consumption increases, the exploitation and
utilization of non-conventional energy resources, such as shale gas
and shale oil, etc., receives attention gradually. The explored
shale oil and gas reservoir in China is huge, and is of great value
for exploration and development. At present, a multi-staged
fracturing method is mainly used in long horizontal wells for shale
gas mining, in order to improve well yield and industrial
exploitation value. Owing to the fact that the shale formation has
high water sensitivity and developed crevices, complicated
situations such as wall collapse and bore shrinkage, etc. may occur
in the drilling process. Therefore, the wall stability problem of
long horizontal wells is a major technical difficulty encountered
in the development of drilling fluids and completion fluids for
shale gas mining.
[0004] At present, oil-based drilling fluids are mainly employed
for horizontal wells in shale formation, and such oil-based
drilling fluid can solve the well wall stability problem
satisfactorily. However, the well yield of shale gas is usually
low, and the cost of oil mud is high, causing compromised
industrial value of shale gas mining; in addition, oil-based
drilling fluids have problems including poor environmental
protection property, high recycling cost, and poor safety, etc.
Water-based drilling fluids have advantages including lower cost,
more environmentally friendly, and easy access to the oil and gas
reservoir, etc. However, common water-based drilling fluid systems
have poor well wall stability performance and inadequate
lubrication and anti jamming capability. Consequently, the
application of water-based drilling fluids in shale oil and gas
exploitation is limited.
[0005] In China, most of the shale gas reservoirs are buried deeply
(e.g., the Lower Cambrian Series shale gas formation in Sichuan
Basin is in 2,000-3,500 m burial depth), have high formation
pressure, and involve complex formations, including super-high
pressure hydrocarbon formation, saltwater formation, and
argillaceous rock formation, etc. When a shale formation that has
high gas content and highly developed crevices is encountered
during well drilling, resulting increased gas leakage may result in
accidents such as well blowout and well kick, etc. By increasing
the density of the drilling fluid, the formation pressure may be
balanced effectively, the well wall stability can be improved, and
the occurrence of complex situations can be prevented.
SUMMARY OF THE INVENTION
[0006] The present invention provides a drilling fluid additive
composition and a water-based drilling fluid, which has higher
density, and higher temperature resistance, plugging and inhibition
performance.
[0007] At present, water-based drilling fluids suitable for shale
gas mining are not satisfactory, mainly in the following aspects:
[0008] (1) The high-temperature resistance performance has to be
improved. As the well depth and the downhole temperature increase,
the requirement for temperature resistance performance of
water-based drilling fluid becomes higher. [0009] (2) The density
is not high generally. Water-based drilling fluids with ordinary
density can't meet the requirement for drilling fluid density in
high-pressure formations any more, but increased drilling fluid
density may bring problems, such as poor rheological property.
[0010] (3) The inhibition performance is not enough. Conventional
water-based drilling fluids are not sufficient to inhibit the
dispersion of shale, and may result in wellbore instability, but
increased inhibition performance may bring problems such as poor
rheological property and plugging performance. [0011] (4) The
plugging performance is not enough. Water-based drilling fluids
with ordinary density can't fully plug micrometer pores in shale
any more.
[0012] To overcome the drawbacks of the existing water-based
drilling fluids, including low density, poor temperature
resistance, plugging and inhibition performance, the present
invention provides a drilling fluid additive composition,
comprising a nano-plugging agent, a bionic wall bracing agent, a
bionic shale inhibitor, an emulsifier, and an amphiphobic
wettability reversal agent, wherein
[0013] the nano-plugging agent is modified silicon dioxide
nano-particle. The modified silicon dioxide nano-particle comprises
a modifying group, which in turn, includes a modifying copolymer
chain, the structural units in the modifying copolymer chains are
provided by one or more of monomers represented by the following
formula (1) and one or more of monomers represented by the
following formula (2):
##STR00001##
[0014] wherein one of R.sup.6-R.sup.10 is -L'-SO.sub.3H and the
rest of R.sup.6-R.sup.10 are independently selected from H, --OH,
halogen, and C1-C10 alkyl; L, L' and L'' are independently selected
from C0-C10 alkylene. The bionic wall bracing agent is
carboxymethyl chitosan with a dopamine-derived group represented by
the following formula (I-1) grafted on its main chain:
##STR00002##
[0015] The bionic shale inhibitor is composed of structural units
represented by the following formula (3) and structural units
represented by the following formula (4):
##STR00003##
the molar ratio of the structural units represented by formula (3)
to the structural units represented by formula (4) is 0.2-6:1, and
the weight-average molecular weight of the bionic shale inhibitor
is 800-4,000 g/mol; the emulsifier is one or more of compounds
represented by the following formula (i):
##STR00004##
[0016] in formula (i), each of the two R.sub.11 groups is
independently selected from C14-C30 alkyl optionally substituted by
group Y and C14-C30 unsaturated alkyl with carbon-carbon double
bonds optionally substituted by group Y, and the group Y is
independently selected from the groups represented by the following
formulae:
##STR00005##
n' is an integer within a range of 1-8; n' X'-es are independently
selected from H and --C(O)--R.sub.21, and at least one X' is
--C(O)--R.sub.21, R.sub.21 is selected from carboxyl, C1-C6 alkyl,
C3-C8 cycloalkyl, C1-C6 alkyl substituted by carboxyl, C3-C8
cycloalkyl substituted by carboxyl, C3-C8 cycloalkyl substituted by
carboxyl and C1-C4 alkyl, C2-C6 unsaturated alkyl with a
carbon-carbon double bond, C3-C8 unsaturated cycloalkyl with a
carbon-carbon double bond, C2-C6 unsaturated alkyl with a
carbon-carbon double bond substituted by carboxyl, and C3-C8
unsaturated cycloalkyl with a carbon-carbon double bond substituted
by carboxyl and C1-C4 alkyl. [0017] The amphiphobic wettability
reversal agent is a dual-cation fluorocarbon surfactant of which
the cation part is represented by the following formula (a):
##STR00006##
[0018] wherein, each R.sup.1 is independently selected from C1-C6
alkyl, each R.sup.2 is independently selected from H and C1-C6
alkyl, each R.sup.3 is independently selected from C1-C10 alkylene,
each n'' is independently selected from integers within a range of
3-15, and m is selected from integers within a range of 1-10.
[0019] The present invention further provides a water-based
drilling fluid containing the above mentioned drilling fluid
additive composition.
[0020] When the water-based drilling fluid contains the drilling
fluid additive composition provided in the present invention, the
water-based drilling fluid would have high temperature-resistance,
high plugging and high inhibition performance, is environment
friendly, especially have high density, and is especially suitable
for horizontal shale gas well mining, and is a pseudo oil-based
drilling fluid suitable for horizontal shale gas wells.
[0021] Other features and advantages of the present invention will
be further detailed in the embodiments hereunder.
BRIEF DESCRIPTION OF DRAWINGS
[0022] The accompanying drawings are provided here to facilitate
further understanding on the present invention, and constitute a
part of this document. They are used in conjunction with the
following embodiments to explain the present invention, but shall
not be comprehended as constituting any limitation to the present
invention. In the figures:
[0023] FIG. 1 is a SEM image of the modified silicon dioxide
nano-particles obtained in the nano-plugging agent preparation
example 1.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0024] Hereunder some embodiments of the present invention will be
detailed. It should be appreciated that the embodiments described
here are only provided to describe and explain the present
invention, but shall not be deemed as constituting any limitation
to the present invention.
[0025] The ends points and any value in the ranges disclosed in the
present invention are not limited to the exact ranges or values.
Instead, those ranges or values shall be comprehended as
encompassing values that are close to those ranges or values. For
numeric ranges, the end points of the ranges, the end points of the
ranges and the discrete point values, and the discrete point values
may be combined to obtain one or more new numeric ranges, which
shall be deemed as having been disclosed specifically in this
document.
[0026] The present invention provides a drilling fluid additive
composition, comprising a nano-plugging agent, a bionic wall
bracing agent, a bionic shale inhibitor, an emulsifier, and an
amphiphobic wettability reversal agent, wherein
the nano-plugging agent is modified silicon dioxide nano-particle,
the modifying group on the modified silicon dioxide nano-particle
includes a modifying copolymer chain, and the structural units in
the modifying copolymer chains are provided by one or more of
monomers represented by the following formula (1) and one or more
of monomers represented by the following formula (2):
##STR00007##
[0027] wherein one of R.sup.6-R.sup.10 is -L''-SO.sub.3H and the
rest of R.sup.6-R.sup.10 are independently selected from H, --OH,
halogen, and C1-C10 alkyl; L, L' and L'' are independently selected
from C0-C10 alkylene;
the bionic wall bracing agent is carboxymethyl chitosan with a
dopamine-derived group represented by the following formula (I-1)
grafted on its main chain:
##STR00008##
[0028] the bionic shale inhibitor is composed of structural units
represented by the following formula (3) and structural units
represented by the following formula (4):
##STR00009##
[0029] the molar ratio of the structural units represented by
formula (3) to the structural units represented by formula (4) is
0.2-6:1, and the weight-average molecular weight of the bionic
shale inhibitor is 800-4,000 g/mol;
the emulsifier is one or more of compounds represented by the
following formula (i):
##STR00010##
[0030] in formula (i), each of the two R.sub.11 groups is
independently selected from C14-C30 alkyl optionally substituted by
group Y and C14-C30 unsaturated alkyl with carbon-carbon double
bonds optionally substituted by group Y, and the group Y is
independently selected from the groups represented by the following
formulae:
##STR00011##
n' is an integer within a range of 1-8;
[0031] n' X'-es are independently selected from H and
--C(O)--R.sub.21, and at least one X' is --C(O)--R.sub.21, R.sub.21
is selected from carboxyl, C1-C6 alkyl, C3-C8 cycloalkyl, C1-C6
alkyl substituted by carboxyl, C3-C8 cycloalkyl substituted by
carboxyl, C3-C8 cycloalkyl substituted by carboxyl and C1-C4 alkyl,
C2-C6 unsaturated alkyl with a carbon-carbon double bond, C3-C8
unsaturated cycloalkyl with a carbon-carbon double bond, C2-C6
unsaturated alkyl with a carbon-carbon double bond substituted by
carboxyl, and C3-C8 unsaturated cycloalkyl with a carbon-carbon
double bond substituted by carboxyl and C1-C4 alkyl; and
the amphiphobic wettability reversal agent is a dual-cation
fluorocarbon surfactant of which the cation part is represented by
the following formula (a):
##STR00012##
[0032] wherein, each R.sup.1 is independently selected from C1-C6
alkyl, each R.sup.2 is independently selected from H and C1-C6
alkyl, each R.sup.3 is independently selected from C1-C10 alkylene,
each n'' is independently selected from integers within a range of
3-15, and m is selected from integers within a range of 1-10.
[0033] According to the present invention, though the nano-plugging
agent, bionic wall bracing agent, bionic shale inhibitor,
emulsifier, and amphiphobic wettability reversal agent may be used
at any ratio and can attain the effects of improving high density,
temperature resistance, plugging, and inhibition performance of the
additive composition and, stabilizing the well wall and protecting
the reservoir. In certain embodiments, the weight ratio of the
nano-plugging agent to the bionic wall bracing agent to the bionic
shale inhibitor to the emulsifier to the amphiphobic wettability
reversal agent is 100:20-500:20-500:20-500:5-100, more preferably
is 100:30-400:30-400:30-300:10-50, even more preferably is
100:50-200:50-200:50-200:10-30, and may be
100:50-100:50-100:50-150:10-20. Particularly preferably, the
present additive composition is composed of the nano-plugging
agent, bionic wall bracing agent, bionic shale inhibitor,
emulsifier, and amphiphobic wettability reversal agent.
[0034] As a result of the modifying groups on the modified silicon
dioxide nano-particles include the modifying copolymer chains, it
is equivalent to that the modifying copolymer chain is grafted on
the nano-silicon dioxide; thereby, a spatial network structure
attained by virtue of noncovalent bonds such as hydrophilic and
hydrophobic groups and hydrogen bonds, etc. and the adsorptive
effect of amido groups, so that the modified silicon dioxide
nano-particles will not agglomerate easily or will not agglomerate
into large-grained agglomerates but maintain high dispersity when
the modified silicon dioxide nano-particles are used as plugging
agent in a drilling fluid; therefore, when the drilling fluid is
inserted into shale, the plugging agent can plug the crevices in
the shale satisfactorily, and can work with other constituents in
the composition, especially the bionic wall bracing agent, bionic
shale inhibitor, emulsifier and amphiphobic wettability reversal
agent in the drilling fluid to attain the purpose of improving the
bearing capability of the formation, stabilize the well wall,
prevent leakage from the well, and protect the oil and gas
reservoir.
[0035] To attain the object described above in a better way,
preferably, one of R.sup.6-R.sup.10 is -L''-SO.sub.3H, and the rest
of R.sup.6-R.sup.10 are independently selected from H, and C1-C6
alkyl; L, L' and L'' are independently selected from C0-C6
alkylene.
[0036] More preferably, one of R.sup.6-R.sup.10 is -L''-SO.sub.3H,
and the rest of R.sup.6-R.sup.10 are independently selected from H,
and C1-C4 alkyl; L, L' and L'' are independently selected from
C0-C4 alkylene.
[0037] Further more preferably, one of R.sup.6-R.sup.10 is
-L''-SO.sub.3H, and the rest of R.sup.6-R.sup.10 are independently
selected from H, methyl, ethyl, propyl and butyl; L' and L'' are
independently selected from C0 alkylene, --CH.sub.2--,
--CH.sub.2--CH.sub.2--, --CH.sub.2--CH.sub.2--CH.sub.2--,
--CH(CH.sub.3)--CH.sub.2--, --C(CH.sub.3).sub.2--CH.sub.2--,
--CH.sub.2--C(CH.sub.3).sub.2-- and
--CH.sub.2--CHCH.sub.3--CH.sub.2--; L is --CH.sub.2--,
--CH.sub.2--CH.sub.2--, --CH.sub.2--CH.sub.2--CH.sub.2--,
--CH(CH.sub.3)--CH.sub.2--, --C(CH.sub.3).sub.2--CH.sub.2--,
--CH.sub.2--C(CH.sub.3).sub.2-- or
--CH.sub.2--CHCH.sub.3--CH.sub.2--. C0 alkylene means that the
groups at the two ends of L, L' or L'' are directly linked, or may
be understood as that L, L' or L'' doesn't exist or is a linking
bond. Optimally, R.sup.8 is -L''-SO.sub.3H.
[0038] Wherein, examples of -L''-SO.sub.3H may include:
--SO.sub.3H, --CH.sub.2--SO.sub.3H,
--CH.sub.2--CH.sub.2--SO.sub.3H,
--CH.sub.2--CH.sub.2--CH.sub.2--SO.sub.3H,
--CH(CH.sub.3)--CH.sub.2--SO.sub.3H,
--C(CH.sub.3).sub.2--CH.sub.2--SO.sub.3H,
--CH.sub.2--C(CH.sub.3).sub.2--SO.sub.3H or
--CH.sub.2--CHCH.sub.3--CH.sub.2--SO.sub.3H.
[0039] Wherein, examples of the C1-C10 alkyl may include: methyl,
ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,
amyl, hexyl, heptyl, octyl, nonyl, and decyl.
[0040] According to the present invention, the monomers represented
by formula (1) are preferably selected from one or more of
compounds represented by the following formulae: [0041] formula
(1-1): in the formula (1), R.sup.8 is --SO.sub.3H, R.sup.6-R.sup.7
and R.sup.9-R.sup.10 are H, and L' is C0 alkylene (also referred to
as p-styrenesulfonic acid); [0042] formula (1-2): in the formula
(1), R.sup.6 is --SO.sub.3H, R.sup.7-R.sup.10 are H, and L' is C0
alkylene (also referred to as o-styrenesulfonic acid); [0043]
formula (1-3): in the formula (1), R.sup.7 is --SO.sub.3H, R.sup.6
and R.sup.8-R.sup.10 are H, and L' is C0 alkylene (also referred to
as m-styrenesulfonic acid); [0044] formula (1-4): in the formula
(1), R.sup.8 is --SO.sub.3H, R.sup.7 is methyl, R.sup.6 and
R.sup.9-R.sup.10 are H, and L' is C0 alkylene (also referred to as
p-2-methyl-4-styrenesulfonic acid).
[0045] According to the present invention, the monomers represented
by formula (2) are preferably selected from one or more of
compounds represented by the following formulae: [0046] formula
(2-1): in the formula (2), L is --CH.sub.2-- (also referred to as
N,N'-methylene-bis acrylamide); [0047] formula (2-2): in the
formula (2), L is --CH.sub.2--CH.sub.2-- (also referred to as
N,N'-ethylidene-bis acrylamide).
[0048] According to the present invention, in a preferred
embodiment of the present invention, the structural units in the
modifying copolymer chain is composed of one or more of structural
units represented by the following formula (1-a) and structural
units represented by the following formula (2-a):
##STR00013##
[0049] Wherein, R.sup.6-R.sup.10, L, L' and L'' are those as
defined above. It is seen: in the preferred embodiment, the
modifying copolymer chain is a linear copolymer chain consisting of
one or more of the structural units represented by formula (1-a)
and one or more of the structural units represented by formula
(2-a), and may be a random linear copolymer chain, or a block
linear copolymer chain, or an alternating linear copolymer chain.
There is no particular restriction on the specific structure of the
linear copolymer chain. However, for convenience, preferably the
linear copolymer chain is a random linear copolymer chain.
[0050] Wherein, the structural units represented by formula (1-a)
and the structural units represented by formula (2-a) may be
selected preferably depending upon the monomers represented by
formula (1) and the monomers represented by formula (2) described
above respectively.
[0051] According to the present invention, as long as the modifying
copolymer chain consists of the structural units provided by the
monomers represented by formula (1) and the structural units
provided by the monomers represented by formula (2), the modifying
copolymer chain can be used as the modifying group on the silicon
dioxide nano-particles to modify the surfaces of the silicon
dioxide nano-particles, so as to avoid a phenomenon that the
silicon dioxide nano-particles agglomerate into large-grain
agglomerates when they are used as a nano-plugging agent in a
drilling fluid and give play to the plugging effect of the modified
silicon dioxide nano-particles. In order to enable the modified
silicon dioxide nano-particles to have better ion compatibility
(mainly evaluated by observing the cooperating effect with other
drilling fluid additives), better high temperature stability, and
better salt resistance property when the modified silicon dioxide
nano-particles are used as a nano-plugging agent, and thereby work
with the bionic wall bracing agent, bionic shale inhibitor,
emulsifier, hydrophobic and oileophobic wettability reversal agent
in the composition in a better way to reduce filter loss of the
drilling fluid, attain a favorable plugging effect, and solve
wellbore instability problems during well drilling, preferably, in
the modifying copolymer chain, the molar ratio of the structural
units provided by the monomers represented by formula (1) to the
structural units provided by the monomers represented by formula
(2) is 1:0.5-5, more preferably is 1:1-2, further more preferably
is 1:1.3-1.6, optimally is 1:1.5-1.6.
[0052] According to the present invention, the molecular weight of
the modifying copolymer chain may vary within a wide range, as long
as the above-mentioned effect can be attained; preferably, the
weight-average molecular weight of the modifying copolymer chain is
100,000-2,500,000 g/mol, more preferably is 300,000-1,800,000
g/mol, further more preferably is 500,000-1,600,000 g/mol, more
preferably is 650,000-1,400,000 g/mol, more preferably is
700,000-1,300,000 g/mol, more preferably is 800,000-1,300,000
g/mol, and may be 860,000-1,280,000g/mol, for example. If the
weight-average molecular weight of the modifying copolymer chain is
within the above-mentioned ranges, especially within the preferred
ranges, the modified silicon dioxide nano-particles have excellent
performance when they are used as a nano-plugging agent.
[0053] According to the present invention, the content of the
modifying copolymer chains on the modified silicon dioxide
nano-particles may vary within a wide range, as long as a
nano-plugging agent with excellent performance can be obtained;
preferably, based on the total weight of the modified silicon
dioxide nano-particles, the content of the modifying copolymer
chains is 60 wt % or higher, more preferably is 85 wt % or higher,
even more preferably is 90 wt % or higher, further more preferably
is 90-98 wt %, optimally is 90-95 wt %.
[0054] According to the present invention, the size of the modified
silicon dioxide nano-particles may be adjusted according to the
crevice condition of the rock stratum. However, it is common
knowledge in the art that the average pore throat size of mud shale
is usually within a range of 10-30 nm; since the modified silicon
dioxide nano-particles in the present invention can be dispersed
well in the drilling fluid and will not agglomerate into large
agglomerated particles when they are used as plugging agent, the
modified silicon dioxide nano-particles in the present invention
may have a wide range of particle diameter, and can attain a good
plugging effect even within the wide range of particle diameter.
Thus, preferably, the particle diameter of the modified silicon
dioxide nano-particles is 3-30 nm, more preferably is 10-30 nm.
[0055] According to the present invention, the modified silicon
dioxide nano-particles that serve as a nano-plugging agent may be
prepared with a conventional method in the art; preferably, the
method for preparing the modified silicon dioxide nano-particles is
as follows: [0056] (1) subjecting one or more of monomers
represented by formula (1) and one or more of monomers represented
by formula (2) to have a contact reaction with silicon dioxide
nano-particles, in the presence of a monohydric alcohol and a
coupler; [0057] (2) subjecting the product of the contact reaction
to have a polymerization reaction, in the presence of a redox
initiator system.
[0058] According to the present invention, formulae (1) and (2) and
the groups involved in them are those as described above, and will
not be detailed further here.
[0059] According to the present invention, in the step (1) in the
method for preparing the modified silicon dioxide nano-particles,
there is no particular restriction on the amount of the monomers
represented by formulae (1) and (2), which is to say, the amount
may be selected according to the modified silicon dioxide
nano-particles described above. For example, to obtain the
modifying copolymer chain consisting of structural units at a
certain molar ratio described above and obtain the modifying
copolymer chain with appropriated molecular weight described above,
preferably the molar ratio of the monomers represented by formula
(1) to the monomers represented by formula (2) is 1:0.5-5, more
preferably is 1:1-2, more preferably is 1:1.3-1.6, more preferably
is 1:1.5-1.6. For example, to make the modified silicon dioxide
nano-particles modified by the modifying copolymer chains described
above, preferably, based on the total amount of the silicon dioxide
nano-particles, the monomers represented by formula (1) and the
monomers represented by formula (2), the total amount of the
monomers represented by formula (1) and the monomers represented by
formula (2) is 60 wt. % or higher, more preferably is 85 wt. % or
higher, even more preferably is 90 wt. % or higher, further more
preferably is 90-98 wt. %, further more preferably is 90-95 wt. %;
in other words, the content of the silicon dioxide nano-particles
is 40 wt. % or lower, preferably is 25 wt. % or lower, more
preferably is 10 wt. % or lower, even more preferably is 2-10 wt.
%, and may be 5-10 wt. %, for example.
[0060] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, the size of
the silicon dioxide nano-particles may be selected according to the
size of the required modified silicon dioxide nano-particles;
preferably, the particle diameter of the silicon dioxide
nano-particles is 3-30 nm, more preferably is 10-30 nm.
[0061] According to the present invention, in the step (1) in the
method for preparing the modified silicon dioxide nano-particles,
in the presence of a coupler, one or more of the monomers
represented by formula (1) and one or more of the monomers
represented by formula (2) are subjected to contact with silicon
dioxide nano-particles firstly (e.g., by mixing), so that active
grafting sites are formed on the silicon dioxide nano-particles
under the action of the coupler, and the silicon dioxide
nano-particles are able to contact sufficiently with the monomers
represented by formula (1) and the monomers represented by formula
(2); in addition, in the presence of the monohydric alcohol, the
reaction rate of the contact reaction and the reaction rate of the
follow-up polymerization reaction can be controlled reasonably, so
that modified silicon dioxide nano-particles required in the
present invention, which will not agglomerate into large particles
and have excellent plugging performance.
[0062] Wherein, there is no particular restriction on the kind of
the monohydric alcohol, as long as the above-mentioned effect can
be attained; preferably, the monohydric alcohol is one or more of
methanol, ethanol, n-propanol and isopropanol, more preferably is
one or more of isopropanol, n-propanol and ethanol. There is no
particular restriction on the amount of the monohydric alcohol, as
long as the reaction rates of the contact reaction and the
polymerization reaction can be controlled and optimized to obtain
silicon dioxide nano-particles modified by modifying copolymer
chains. Preferably, the weight ratio of the silicon dioxide
nano-particles to the monohydric alcohol is 1:5-30, more preferably
is 1:8-25, even more preferably is 1:10-20, and may be 1:15-20, for
example.
[0063] Further, there is no particular restriction on the kind of
the coupler, as long as the above-mentioned effect can be attained.
For example, the coupler may be one or more of silane coupler and
the like, preferably is silane coupler, more preferably is one or
more of .gamma.-aminopropyl-triethoxysilane (also referred to as
KH550), .gamma.-glycidol ether propoxy-trimethoxysilane (also
referred to as KH560),
.gamma.-(methylacryloyloxy)propyl-trimethoxysilane (also referred
to as KH570), and
N-(.beta.-aminoethyl)-.gamma.-aminopropyl-trimethoxysilane (also
referred to as KH792). There is no particular restriction on the
amount of the coupler, as long as the silicon dioxide
nano-particles are activated appropriately to obtain an appropriate
amount of sites where the modifying copolymer chain can be grafted.
Preferably, the weight ratio of the silicon dioxide nano-particles
to the coupler is 100:0.2-10, more preferably is 100:0.4-5, even
more preferably is 100:1-4, optimally is 100:1.2-3, and may be
100:1.2-2, for example.
[0064] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, though the
step (1) may be implemented by adding the monohydric alcohol,
coupler, one or more of the monomers represented by formula (1),
and one or more of the monomers represented by formula (2) together
into the reaction system, alternatively they may be mixed in
separate steps freely and then the obtained mixtures may be mixed
together. There is no particular restriction on the specific
implementation in the present invention. In certain embodiments,
step (1) comprises: mixing the monomers represented by formula (1)
and the monomers represented by formula (2) firstly (e.g., mixing
at 10-40.degree. C. (preferably 20-30.degree. C.) while stirring at
a speed of 200-500 rpm (preferably 250-350 rpm) for 10-40 min
(preferably 20-30 min)), and adjusting the pH of the obtained
mixture to 7-9, preferably 7-8, more preferably 7-7.5 (e.g., one or
more of sodium hydroxide, potassium hydroxide, and lithium
hydroxide, etc. can be used to make the adjustment); then,
subjecting the mixture to have a contact reaction with the silicon
dioxide nano-particles, in the presence of a monohydric alcohol and
a coupler. In certain embodiments, the step (1) comprises:
preparing a mixture (hereinafter referred to as mixture A) of
monomers represented by formula (1) and monomers represented by
formula (2); preparing a mixture (hereinafter referred to as
mixture B) of the monohydric alcohol and the silicon dioxide
nano-particles (e.g., stirring for 10-40 min (preferably 20-30 min)
at 200-500 rpm (preferably 250-350 rpm) stirring speed at
10-40.degree. C. (preferably 20-30.degree. C.)); mixing the mixture
A with the mixture B to prepare a mixture C (e.g., stirring for
10-40 min (preferably 20-30 min) at 200-500 rpm (preferably 250-350
rpm) stirring speed at 10-40.degree. C. (preferably 20-30.degree.
C.)); then, subjecting the mixture C to have the contact reaction
in the presence of a coupler.
[0065] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, preferably,
in the step (1), the conditions of the contact reaction include:
temperature of 10-40.degree. C. (preferably 20-30.degree. C.), and
time of 10-60 min (preferably 20-30 min).
[0066] According to the present invention, in the step (2) of the
method for preparing the modified silicon dioxide nano-particles,
under the initiation action of the redox initiator system, the
monomers represented by formula (1) and the monomers represented by
formula (2) are copolymerized, and grafted on the silicon dioxide
nano-particles, so that modified silicon dioxide nano-particles
grafted with the modifying copolymer chains are obtained.
Generally, the modifying copolymer chains in the present invention
may be understood as linear polymer chains, but are not limited to
linear polymer chains.
[0067] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, there is no
particular restriction on the kind of the redox initiator system,
as long as the above-mentioned purpose can be attained; preferably,
the reducer in the redox initiator system is sodium bisulfite.
Preferably, the oxidizer in the redox initiator system is ammonium
persulfate. Wherein, the molar ratio of the reducer to the oxidizer
preferably is 1:1-5, more preferably is 1:2.5-3. There is no
particular restriction on the amount of the redox initiator system,
as long as the modified silicon dioxide nano-particles grafted with
the modifying copolymer chains required in the present invention
can be obtained; preferably, with respect to 1 mol total amount of
the monomers represented by formula (1) and the monomers
represented by formula (2), the amount of the redox initiator
system is 0.05-1 g, more preferably is 0.07-0.8 g, even more
preferably is 0.1-0.4 g, still more preferably is 0.14-0.3 g, and
may be 0.2-0.28 g, for example.
[0068] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, preferably,
in the step (2), the conditions of the polymerization reaction
include: temperature of 40-80.degree. C. (preferably 50-70.degree.
C., e.g., 60.degree. C.), and time of 3-6 h (preferably 4-5 h). The
polymerization reaction may be carried out while stirring, for
example, at 200-400 rpm stirring speed.
[0069] According to the present invention, in the method for
preparing the modified silicon dioxide nano-particles, to extract
the modified silicon dioxide nano-particles from the polymerization
reaction system, the method may further comprise: drying the
product of the polymerization reaction (e.g., drying for 5-20 h at
50-80.degree. C., preferably at 60-70.degree. C.) and milling it,
to obtain the modified silicon dioxide nano-particles. Here, the
product of the polymerization reaction is directly dried and
milled, and then the obtained particles may be used as the
nano-plugging agent in the drilling fluid. Therefore, the product
obtained with the above method is directly used as modified silicon
dioxide nano-particles, which include silicon dioxide particles
with modifying copolymer chains grafted on the silicon dioxide
nano-particles, silicon dioxide nano-particles with modifying
copolymer coated on the particles, and other possible
particles.
[0070] According to the present invention, the mechanism of action
of the bionic wall bracing agent is as follows: the byssus threads
of a mussel can adhere to the rock surface in the marine
environment, and dopamine--a special amino acid derivative
contained in byssus protein--is proved to be the key factor for
strong subaqueous adhesion of byssus threads. When a mussel
secretes byssus protein from its body onto a seabed rock surface,
the dopamine groups in the byssus protein will have a cross-linking
cure reaction with Fe.sup.3+ions in seawater, and thereby cohesive
byssus threads with strong adhesion are formed, so that the mussel
adheres to the rock surface. A bionic well wall strengthener
developed by simulating the structure of adhesive proteins produced
by a mussel can contact with and is absorbed to the surface of clay
shale along with the drilling fluid in the borehole drilling
process, and is cross-linked and cured under the complexing action
between the dopamine groups and the Fe.sup.3+ ions on the surface
of clay shale to form a layer of polymer film in 100 .mu.m-1 mm
thickness (the thickness increases as the polymer concentration in
the drilling fluid increases), which has strong adhesion. The
polymer film not only can effectively prevent the drilling fluid
from infiltrating into the formation, but also has enough strength
to partially balance off the hydration stress borne on the rock,
and thereby attains an effect of plugging the pores in the clay
shale of borehole wall and improving the strength of the clay
shale.
[0071] According to an embodiment of the present invention, the
bionic wall bracing agent contains structural units represented by
formula (I):
##STR00014##
In formula (I), R.sub.1 is H,
##STR00015##
R.sub.2 is H,
##STR00016##
[0072] and at least one of R.sub.1 and R.sub.2 is
##STR00017##
n is an integer equal to or greater than 1, each of the n R.sub.5
groups is H or a dopamine-derived group respectively and
independently, and at least one of the n R.sub.5 groups is the
dopamine-derived group, R.sub.4 is H or C.sub.1-C.sub.10 alkyl,
R''' is H, --CH.sub.2COOR.sub.3' or --CH.sub.2COOR.sub.3, and
R.sub.1 and R''' are not H at the same time, R.sub.3' is H or
alkali metal, and R.sub.3 is the dopamine-derived group.
[0073] The weight-average molecular weight of the bionic wall
bracing agent may be 20,000 g/mol-150,000 g/mol, preferably is
50,000 g/mol-100,000 g/mol.
[0074] According to an embodiment of the present invention, in
formula (I), R.sub.4 is C2-C20 alkyl, more preferably is C2-C6
alkyl. Examples of R.sub.4 include, but are not limited to: ethyl,
propyl, iso-propyl, and butyl.
[0075] According to an embodiment of the present invention, the
bionic wall strengthener is prepared with a method comprising the
following steps: [0076] (1) initiating a graft copolymerization
reaction between a polymer that contains the structural units
represented by formula (III) and an unsaturated carboxylic acid
represented by general formula R.sub.4CH.dbd.CHCOOH; [0077] (2)
reacting the polymer obtained in step (1) with at least one of
dopamine and dopamine hydrochloride;
##STR00018##
[0078] Wherein R' and R'' are H or --CH.sub.2COOR.sub.3'
respectively and independently, and R' and R'' are not H at the
same time; R3' is H or an alkali metal element; R.sub.4 is H or
C.sub.1-C.sub.10 alkyl.
[0079] In the preparation process of the bionic wall bracing agent,
in step (1), the conditions of the graft copolymerization reaction
may include: temperature of 50-90.degree. C., preferably
60-80.degree. C.; time of 1-1 h, preferably 2-6 h; the molar ratio
of the polymer that contains the structural units represented by
formula (III) (calculated by hydroxyl groups) to the unsaturated
carboxylic acid may be 1:0.1-4, preferably is 1:0.5-3; the graft
copolymerization reaction may proceed in the presence of an
initiator, which may be one or more of ammonium ceric nitrate,
potassium persulfate, and ammonium persulfate.
[0080] In certain embodiments, the polymer that contains the
structural units represented by formula (III) is carboxymethyl
chitosan. Preferably, the carboxymethyl chitosan is mixed, contacts
with, and have a graft copolymerization reaction with the
unsaturated carboxylic acid in the form of water solution. The
water solution of carboxymethyl chitosan may be obtained by
dissolving carboxymethyl chitosan (with 10,000 g/mol-80,000 g/mol
weight-average molecular weight) in water while stirring (the
stirring speed may be 100-500 rpm). The amount of water can be
determined appropriately, as long as the carboxymethyl chitosan can
be dissolved completely; preferably, the weight ratio of
carboxymethyl chitosan to water is 1:20-50.
[0081] The unsaturated carboxylic acid may be an unsaturated
monocarboxylic acid with carbon number equal to or greater than 3;
the carbon number in the unsaturated carboxylic acid preferably is
3-11, more preferably is 3-7. The examples of the unsaturated
carboxylic acid include, but are not limited to acrylic acid and/or
methacrylic acid.
[0082] In the preparation process of the bionic wall bracing agent,
in step (2), the conditions of the condensation reaction may
include: temperature of 10-50.degree. C., preferably 20-40.degree.
C.; time of 2-48 h, preferably 6-36 h. The mole ratio of the amount
of the polymer prepared in step (1) (calculated by carboxyl groups)
to the total amount of the dopamine and dopamine hydrochloride
(calculated by amine groups) may be 1:0.01-0.2, preferably is
1:0.02-0.1. The condensation reaction may proceed in the presence
of a catalyst, which may be 1-ethyl-3-(3-dimethyllaminopropyl)
carbonyl diimine hydrochlide or N,N'-diisopropyl carbodiimide.
[0083] According to the present invention, the bionic shale
inhibitor has nanometer-level pores that have high positive charge
density and are easy to enter into mud shale and absorb to the
surface of clay minerals, and thereby can greatly compress the
surface electric double layer of clay, decrease the swelling
pressure of clay, and prevent well wall instability resulted from
clay swelling. Furthermore, the bionic shale inhibitor produced
from amino acids in organisms can be biodegraded in a short period
after it is disposed with the waste drilling fluid by landfill
disposal subsequently. Hence the bionic shale inhibitor has
favorable environmental friendliness. Thus, it can work well with
the nano-plugging agent, bionic wall bracing agent, emulsifier, and
amphiphobic wettability reversal agent in the composition, and,
when applied in a water-based drilling fluid, can improve the
temperature-resistance, plugging, and inhibition performance of the
obtained drilling fluid, and work with the filler to obtain a
high-density drilling fluid and maintain high environmental
protection performance.
[0084] According to the present invention, the weight-average
molecular weight of the bionic shale inhibitor is 800-4,000 g/mol,
preferably is 1,550-4,000 g/mol, more preferably is 1,600-3,300
g/mol. By confining the weight-average molecular weight of the
bionic shale inhibitor disclosed in the present invention within
the above-mentioned range, the bionic shale inhibitor can
effectively diffuse into pores in mean pore size within 4-10 nm
range in shale strata at 2,000 m or greater burial depth, and the
bionic shale inhibitor has high adsorptive capacity and adsorptive
strength on the surface of clay shale. In contrast, if the
weight-average molecular weight of the bionic shale inhibitor is
higher than 4,000 g/mol, it will be difficult for the bionic shale
inhibitor to diffuse into the pores in mean pore size within 4-10
nm range in shale strata at 2,000 m or greater burial depth. If the
weight-average molecular weight of the bionic shale inhibitor is
lower than 800 g/mol, the bionic shale inhibitor will not have
enough adsorptive strength on the surface of clay shale. The
molecular weight distribution index Mw/Mn of the bionic shale
inhibitor may be 1.5-3, for example.
[0085] According to the present invention, the structural units
represented by formula (2)
##STR00019##
have a main chemical structure of arginine, and the structural
units represented by formula (3)
##STR00020##
have a main chemical structure of lysine. In the present subject
matter, the structural units represented by formula (2) and the
structural units represented by formula (3) are selected to
constitute the bionic shale inhibitor disclosed in the present
subject matter, because: on one hand, the structural units
represented by formula (2) and the structural units represented by
formula (3) are in amino acid structure and easy to be degraded by
microbes; therefore, they can be defined as a "bionic shale
inhibitor"; on the other hand, the structural unit represented by
formula (2) has three loci (e.g.,
##STR00021##
where cationic nitrogen can be formed, and the structural unit
represented by formula (3) has one locus (e.g.,
##STR00022##
where cationic nitrogen can be formed; hence, by combining the
structural units represented by formula (2) with the structural
units represented by formula (3), a bionic shale inhibitor that has
an appropriate quantity of cations and superior shale inhibition
capability can be formed. There is no particular restriction on the
terminal groups of the bionic shale inhibitor composed of the
structural units represented by formula (2) and the structural
units represented by formula (3) in the present subject matter. In
other words, the terminal groups can be ordinary groups, such as H,
hydroxyl, or salts, etc.
[0086] According to the present invention, though it is only
required that the bionic shale inhibitor should have weight-average
molecular weight within 800-4,000 g/mol range and should be
composed of the structural units represented by formula (3) and the
structural units represented by formula (4), preferably the mole
ratio of the structural units represented by formula (3) to the
structural units represented by formula (4) is 0.3-5:1, more
preferably is 1-5:1, even more preferably is 1-4:1, optimally is
2-4:1, in order to ensure that the bionic shale inhibitor has
better shale inhibition capability and can be more easily degraded
by microbes subsequently. In a bionic shale inhibitor composed of
the structural units represented by formula (3) and the structural
units represented by formula (4) at the preferred mole ratio, the
structural units represented by formula (3) and the structural
units represented by formula (4) can work more synergistically to
improve the shale inhibition capability and biodegradability of the
bionic shale inhibitor, and the cost of the bionic shale inhibitor
is lower.
[0087] There is no particular restriction on the structure of the
binary polyamino acid. In other words, the binary polyamino acid
can be a regular block copolymer, partially regular block
copolymer, or random copolymer. To avoid introducing complexities
into the production process, the bionic shale inhibitor disclosed
in the present subject matter preferably is a random copolymer.
[0088] According to an embodiment of the present invention, the
method for preparing the bionic shale inhibitor comprises:
initiating a condensation reaction between arginine and lysine in
the presence of an inorganic acid catalyst, wherein, the molar
ratio of the concentration of the arginine to the concentration of
the lysine is 0.2-6:1, and the conditions of the condensation
reaction ensure that the weight-average molecular weight of the
resultant bionic shale inhibitor is 800-4,000 g/mol.
[0089] According to the present invention, in the method for
preparing the bionic shale inhibitor, the arginine may be of
L-type, D-type, or a mixture of the two types; the lysine may be of
L-type, D-type, or a mixture of the two types. Preferably
L-arginine and L-lysine are used.
[0090] According to the present invention, in the method for
preparing the bionic shale inhibitor, there is no particular
restriction on the amounts of the arginine and the lysine, as long
as the product of the condensation reaction has 800-4,000 g/mol
weight-average molecular weight. In certain embodiments, the mole
ratio of the arginine to the lysine is 0.3-0.5:1, more preferably
is 1-5:1, even more preferably is 1-4:1, optimally is 2-4:1.
[0091] According to the present invention, in the method for
preparing the bionic shale inhibitor, the condensation reaction is
performed in the presence of an inorganic acid catalyst. In the
present invention, utilizing an inorganic acid catalyst rather than
an alkaline compound has two purposes: one purpose is to promote
the condensation reaction between the arginine and the lysine, so
as to obtain the bionic shale inhibitor disclosed in the present
invention at a higher yield ratio, while avoiding excessively high
molecular weight of the polymer obtained through the condensation
reaction; the other purpose is to enable the resultant polymer to
bear cationic nitrogen at a higher level, so as to provide cations
to the bionic shale inhibitor. Specifically, the inorganic acid
catalyst may be at least one of sulfuric acid, nitric acid,
phosphoric acid and hydrochloric acid at 1-6 mol/L concentration,
preferably is phosphoric acid (e.g., 85-98 wt. % concentrated
phosphoric acid). When phosphoric acid is used as the inorganic
acid catalyst, the bionic shale inhibitor disclosed in the present
invention can be obtained at a higher yield ratio.
[0092] According to the present invention, in the method for
preparing the bionic shale inhibitor, preferably, the mole ratio of
the amount of the inorganic acid catalyst to the total amount of
arginine and lysine is 1:0.3-3, more preferably is 1:0.4-3.
[0093] According to the present invention, in the method for
preparing the bionic shale inhibitor, preferably, the inorganic
acid catalyst is phosphoric acid, and the mole ratio of the amount
of the phosphoric acid to the total amount of the arginine and
lysine is 1:2-3. Thus, a bionic shale inhibitor with more
appropriate weight-average molecular weight can be obtained.
[0094] According to the present invention, in the method for
preparing the bionic shale inhibitor, there is no particular
restriction on the conditions of the condensation reaction in the
present invention, as long as the bionic shale inhibitor with
800-4,000 g/mol weight-average molecular weight can be prepared
from the arginine and the lysine at the specified mole ratio. In
other words, ordinary conditions for synthesis of an amino acid
polymer in the art can be used, for example, a condensation
reaction between arginine and lysine in melted state. Preferably,
the conditions of the condensation reaction include: temperature of
180-230.degree. C. and time of 4-20 h. More preferably, the
conditions of the condensation reaction include: temperature of
195-215.degree. C. and time of 8-16 h.
[0095] According to the present invention, in the method for
preparing the bionic shale inhibitor, the method for preparing the
bionic shale inhibitor provided in the present invention may
further comprise: adjusting the pH of the mixture obtained through
the condensation reaction to 6-7, after the condensation reaction
is finished. In such a case, the ph may be adjusted with any
alkaline compound, such as at least one of alkali metal hydroxides
(e.g., sodium hydroxide, potassium hydroxide, and lithium
hydroxide), alkali oxides (e.g., sodium oxide, potassium oxide,
lithium oxide), alkali carbonates (e.g., sodium carbonate,
potassium carbonate, and lithium carbonate), and alkali
bicarbonates (e.g., sodium bicarbonate and potassium bicarbonate),
etc. The alkaline compound may be used in the form of solution or
in the form of solid (e.g., powder or grain form, such as sodium
hydroxide powder). Preferably, the alkaline compound is used in the
form solution; more preferably, the concentration of the alkaline
compound solution is 1-10 mol/L. More preferably, the alkaline
compound solution is 3-5 mol/L sodium hydroxide solution, 3-5 mol/L
potassium hydroxide solution, or saturated sodium carbonate
solution. According to the present invention, to obtain the polymer
through the condensation reaction, the method may further comprise:
concentrating, drying, and grinding the solution after pH
adjustment.
[0096] According to the present invention, in the method for
preparing the bionic shale inhibitor, preferably the method for
preparing the bionic shale inhibitor provided in the present
invention further comprises: adding water for dissolution when the
temperature drops to 125.degree. C. or a lower value after the
reaction is completed; separating the obtained water solution and
drying the obtained solid, and then dissolving the obtained solid
in dimethyl sulfoxide; finally, evaporating the obtained liquid to
obtain the bionic shale inhibitor disclosed in the present
invention.
[0097] The emulsifier is one or more of compounds represented by
the following formula (i):
##STR00023##
in formula (i), each of the two R.sub.11 groups is independently
selected from C14-C30 alkyl optionally substituted by group Y and
C14-C30 unsaturated alkyl with carbon-carbon double bonds
optionally substituted by group Y, and the group Y is independently
selected from the groups represented by the following formulae:
##STR00024##
n' is an integer within a range of 1-8;
[0098] n' X'-es are independently selected from H and
--C(O)--R.sub.21, and at least one X' is --C(O)--R.sub.21, R.sub.21
is selected from carboxyl, C1-C6 alkyl, C3-C8 cycloalkyl, C1-C6
alkyl substituted by carboxyl, C3-C8 cycloalkyl substituted by
carboxyl, C3-C8 cycloalkyl substituted by carboxyl and C1-C4 alkyl,
C2-C6 unsaturated alkyl with a carbon-carbon double bond, C3-C8
unsaturated cycloalkyl with a carbon-carbon double bond, C2-C6
unsaturated alkyl with a carbon-carbon double bond substituted by
carboxyl, and C3-C8 unsaturated cycloalkyl with a carbon-carbon
double bond substituted by carboxyl and C1-C4 alkyl.
[0099] According to the present invention, the emulsifier is one or
more of compounds represented by formula (i). The compound
represented by formula (i) is a compound in a comb structure, with
saturated and/or unsaturated long alkyl chains at the two ends and
a short alkyl chain in the middle. Such a compound in a comb
structure can increase the strength of the emulsion interface film,
work with the nano-plugging agent, bionic wall bracing agent,
bionic shale inhibitor, filler and amphiphobic wettability reversal
agent obtained in the present invention to stabilize the drilling
fluid and enables the drilling fluid to have appropriate shearing
force and density and thereby has suspending power, and attain the
purpose of improving the temperature resistance property of the
drilling fluid in such a case.
[0100] Preferably, in Formula (i), each of the two R.sub.11 groups
is independently selected from C14-C20 alkyl optionally substituted
by group Y and C14-C20 unsaturated alkyl with a carbon-carbon
double bond optionally substituted by group Y (preferably with not
more than 5 carbon-carbon double bonds, 1, 2 or 3 for example); n
is an integer of 1-6; R.sub.21 is selected from carboxyl, C1-C4
alkyl, C4-C6 cycloalkyl, C1-C4 alkyl substituted by carboxyl, C4-C6
cycloalkyl substituted by carboxyl, C4-C6 cycloalkyl substituted by
carboxyl and methyl, C2-C4 unsaturated alkyl with a carbon-carbon
double bond (preferably with 1-3 carbon-carbon double bonds, 1, 2
or 3 for example), C4-C6 unsaturated cycloalkyl with a
carbon-carbon double bond (preferably with not more than 5
carbon-carbon double bonds, 1, 2 or 3 for example), C2-C4
unsaturated alkyl with a carbon-carbon double bond substituted by
carboxyl (preferably with 1-3 carbon-carbon double bonds, 1, 2 or 3
for example), and C4-C7 unsaturated cycloalkyl with a carbon-carbon
double bond substituted by carboxyl and methyl (preferably with not
more than 5 carbon-carbon double bonds, 1, 2 or 3 for example).
[0101] More preferably, in Formula (i), each of the two R.sub.11
groups is independently selected from C15-C18 alkyl optionally
substituted by group Y and C15-C18 unsaturated alkyl with a
carbon-carbon double bond optionally substituted by group Y; n' is
an integer of 1-4, for example 1, 2, 3 or 4.
[0102] According to the present invention, the two R.sub.11 groups
are selected independently and may be same or different. The
embodiments of R.sub.11 for example may include the following
groups: --(CH.sub.2).sub.7--CH.dbd.CH--(CH.sub.2).sub.7--CH.sub.3,
--(CH.sub.2).sub.8--CH(Y)--(CH.sub.2).sub.7--CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--(CH.sub.2).sub.8--CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH(Y)--(CH.sub.2).sub.7--CH.sub.3,
--(CH.sub.2).sub.16--CH.sub.3,
--(CH.sub.2).sub.7--CH.dbd.CH--CH.sub.2--CH.dbd.CH--(CH.sub.2).sub.4--CH.-
sub.3,
--(CH.sub.2).sub.7--CH.dbd.CH--CH.sub.2--CH.sub.2--CH(Y)--(CH.sub.2-
).sub.4--CH.sub.3,
--(CH.sub.2).sub.7--CH.dbd.CH--CH.sub.2--CH(Y)--(CH.sub.2).sub.5--CH.sub.-
3,
--(CH.sub.2).sub.8--CH(Y)--CH.sub.2--CH.dbd.CH--(CH.sub.2).sub.4--CH.su-
b.3,
--(CH.sub.2).sub.7--CH(Y)--CH.sub.2--CH.sub.2--CH.dbd.CH--(CH.sub.2).-
sub.4--CH.sub.3,
--(CH.sub.2).sub.7--CH.dbd.CH--CH.sub.2--CH(Y)--CH(Y)--(CH.sub.2).sub.4---
CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH(Y)--CH.sub.2--CH.dbd.CH--(CH.sub.2-
).sub.4--CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH(Y)--CH.sub.2--CH(Y)--(CH.sub.2).sub.5--CH.s-
ub.3,
--(CH.sub.2).sub.8--CH(Y)--CH.sub.2--CH(Y)--CH(Y)--(CH.sub.2).sub.4--
-CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH.sub.2--CH.sub.2--CH(Y)--CH(Y)--(C-
H.sub.2).sub.4--CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH(Y)--CH.sub.2--CH.sub.2--CH(Y)--(CH.sub.2).s-
ub.4--CH.sub.3,
--(CH.sub.2).sub.7--CH(Y)--CH(Y)--CH.sub.2--CH(Y)--CH(Y)--(CH.sub.2).sub.-
4--CH.sub.3, --(CH.sub.2).sub.14--CH.sub.3,
--(CH.sub.2).sub.13--CH.sub.3. where group Y, as described above,
is selected from
##STR00025##
The connecting dotted lines on these groups stand for linkage sites
linking the carbon atoms on R.sub.11.
[0103] According to the present invention, the embodiments of group
R.sub.21 for example may include: carboxyl, methyl, ethyl, propyl,
cyclopentyl, cyclohexyl, --CH.sub.2--COOH (referring to C1 alkyl
substituted by a carboxyl group), --(CH.sub.2).sub.2--COOH
(referring to C2 alkyl substituted by a carboxyl group),
--CH(CH.sub.2--COOH).sub.2 (referring to C3 alkyl substituted by
two carboxyl groups),
##STR00026##
[0104] According to the present invention, the foregoing emulsifier
may be a product available in the market and may also be prepared
by a conventional method of the art. Preferably, the method for
preparing the emulsifier comprises: subjecting a polyamine compound
represented by Formula (ii) to take amidation reaction with one or
more of carboxylic acids represented by Formula R.sub.11'--COOH
(e.g., reacting the polyamine with a carboxylic acid of
R.sub.11'--COOH), and contacting and reacting the reaction product
with one or more of carboxylic acids R.sub.21--COOH and anhydrides
thereof;
Formula (ii)
##STR00027##
[0105] where R.sub.21 and n' have been described above, so no
necessary details will be given herein.
[0106] R.sub.11' is selected from C14-C30 alkyl and C14-C30
unsaturated alkyl with a carbon-carbon double bond.
[0107] The embodiments of the carboxylic acids represented by
Formula R.sub.11'--COOH for example may include:
COOH--(CH.sub.2).sub.7--CH.dbd.CH--(CH.sub.2).sub.7--CH.sub.3 (also
called as oleic acid),
COOH--(CH.sub.2).sub.7--CH.dbd.CH--CH.sub.2--CH.dbd.CH--(CH.sub.2).sub.4--
-CH.sub.3 (also called as linoleic acid),
COOH--(CH.sub.2).sub.16--CH.sub.3 (also called as octadecanoic
acid), COOH--(CH.sub.2).sub.14--CH.sub.3 (also called as
hexadecanoic acid or palmitic acid),
COOH--(CH.sub.2).sub.13--CH.sub.3 (also called as pentadecanoic
acid).
[0108] The embodiments of carboxylic acids represented by Formula
R.sub.21--COOH and anhydrides thereof for example may include:
HOOC--COOH (oxalate), CH.sub.3--COOH (acetic acid),
CH.sub.3--COO--CO--CH.sub.3 (acetic anhydride),
HOOC--CH.sub.2--COOH (malonic acid), HOOC--CH.sub.2--CH.sub.2--COOH
(succinic acid), HOOC--CH.sub.2--CH(COOH)--CH.sub.2--COOH
(tricarballylic acid),
##STR00028##
[0109] According to the present invention, the embodiments of the
polyamine represented by Formula (ii) for example may include:
##STR00029##
[0110] According to the present invention, the amidation reaction
between the polyamine represented by foregoing Formula (ii) and the
carboxylic acid represented by R.sub.11'--COOH mainly refers to the
amidation reaction between the primary amine of the polyamine
represented by foregoing Formula (ii) and the carboxylic group of
the carboxylic acid represented by R.sub.11'--COOH, with water
molecules removed to form amido bonds, thereby obtaining one or
more of compounds with secondary amine not substituted in the
middle of the chain as represented by
[0111] Formula (i')
##STR00030##
Preferably, the molar ratio of the polyamine compound represented
by Formula (ii) and the carboxylic acid represented by Formula
R.sub.11'--COOH is 1:1.8-3, preferably 1:1.8-2.2.
[0112] According to the present invention, preferably, the
conditions of the amidation reaction comprise: the temperature is a
temperature of 220-230.degree. C., pH value of 7-9 and a time of
3-5 h. In order to make amidation reaction more sufficient, this
method may further comprise: firstly mixing the polyamine
represented by Formula (ii) with one or more of carboxylic acids
represented by R.sub.11'--COOH for 10-30 min under a stirring rate
of 80-300 r/min, then taking the amidation reaction under a
stirring rate of 80-300 r/min, and water is trapped by water
knockout trap during amidation reaction.
[0113] According to the present invention, the emulsifier of the
present invention may be obtained through contacting and reacting
the above reaction product of the amidation reaction with one or
more of the carboxylic acids represented by R.sub.21--COOH and
anhydrides thereof. The reaction product of amidation reaction may
be purified to obtain the compound represented by
##STR00031##
alternatively, the reaction product of amidation reaction without
purification may directly contact and react with one or more of the
carboxylic acids represented by R.sub.21--COOH and anhydrides
thereof so as to link-C(O)--R.sub.21 substituent to the secondary
amine between two amido bonds, thereby forming the compound with a
comb-like structure represented by Formula (i). Preferably, the
molar ratio of the polyamine compound represented by Formula (ii)
and the carboxylic acids represented by Formula R.sub.21--COOH and
anhydrides thereof is 1:0.5-20. For example, the molar ratio of the
polyamine compound represented by Formula (ii) and the carboxylic
acids represented by Formula R.sup.2--COOH and anhydrides thereof
is 1:1.8-2.2, 1:3.6-4.4, 1:5.4-6.6, 1:7.2-8.8, 1:9-11,
1:10.8-13.2.
[0114] According to the present invention, when the carboxylic acid
represented by R.sub.11'--COOH is an unsaturated carboxylic acid
with a carbon-carbon double bond, and the carboxylic acids
represented by Formula R.sub.21--COOH and anhydrides thereof
adopted in the process of the contract reaction also contain a
carbon-carbon double bond, then in the process of the contact
reaction, addition reaction may also occur between the
carbon-carbon double bond in the carboxylic acids represented by
Formula R.sup.2--COOH (and anhydrides thereof) and the
carbon-carbon double bond in the reaction product of the amidation
reaction, thereby obtaining the compound with R.sub.11 (shown in
Formula (i)) substituted by group Y. Although the present invention
does not have particular limitation to this, the compound obtained
under this case is also included in the emulsifier described in the
present invention.
[0115] According to the present invention, the conditions of the
contact reaction comprise: a temperature of 75-90.degree. C., pH
value of 7-9 and a time of 6-10 h. In order to make contact
reaction more sufficient, this method may further comprise:
contacting and reacting the reaction product of the amidation
reaction with one or more of the carboxylic acids represented by
Formula R.sub.21--COOH and anhydrides thereof under a stirring
rater of 200-500 r/min, and water is trapped by water knockout trap
during the contact reaction.
[0116] According to the present invention, it should be noted that
the emulsifier of the present invention may be one of the compounds
represented by Formula (i), but if the foregoing preparation method
is adopted, the emulsifier may also be one of the compounds
represented by Formula (i) obtained through purifying and
separating the product obtained by the foregoing preparation
method. However, as more effective operation, the emulsifier of the
present invention may be more of the compounds represented by
Formula (i), i.e.: if the foregoing preparation method is adopted,
the emulsifier may be a product directly obtained by the foregoing
preparation method and is uses without purification. In other
words, it may be understood that the emulsifier of the present
invention is a product obtained by the foregoing method without
purification.
[0117] According to the present invention, the dual-cation
fluorocarbon surfactant can serve as an amphiphobic wettability
reversal agent when it is used in a drilling fluid; thus, when the
drilling fluid is used for oil and gas drilling, the molecules of
the dual-cation fluorocarbon surfactant can be absorbed to the rock
surface easily owing to the fact that the molecules have low
surface tension, and thereby the rock obtains an amphiphobic
property. As a result, permeation of water and oil into the rock
can be avoided effectively and thereby a capillary phenomenon can
be prevented, and an effect of stabilizing the well wall and
protecting the reservoir is attained.
[0118] In the present invention, the C1-C6 alkyl may be methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
tert-butyl, n-pentyl, isopentyl, n-hexyl, etc., for example.
[0119] The C1-C10 alkylene may be the alkylene formed by C1-C6
alkyl described above, or n-heptyl, n-nonyl, or n-decyl, etc.
[0120] According to the present invention, preferably, in formula
(a), each R.sup.1 is selected from C1-C4 alkyl respectively and
independently, each R.sup.2 is independently selected from H and
C1-C4 alkyl, each R.sup.3 is independently selected from C2-C8
alkylene, each n'' is independently selected from integers within a
range of 4-10, and m is selected from integers within a range of
2-8.
[0121] More preferably, in formula (a), each R.sup.1 is
independently selected from C1-C4 alkyl, each R.sup.2 is
independently selected from H and C1-C4 alkyl, each R.sup.3 is
independently selected from C2-C6 alkylene, each n'' is
independently selected from integers within a range of 4-8, and m
is selected from integers within a range of 3-6.
[0122] Further more preferably, in formula (a), each R.sup.1 is
independently selected from methyl, ethyl, n-propyl, isopropyl, and
n-butyl, each R.sup.2 is independently selected from H, methyl,
ethyl, n-propyl, isopropyl, and n-butyl, each R.sup.3 is
independently selected from --CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--CH.sub.2--, --CH(CH.sub.3)--CH.sub.2--,
--CH.sub.2--CH(CH.sub.3)--,
--CH.sub.2--(CH.sub.2).sub.2--CH.sub.2--,
--CH.sub.2--(CH.sub.2).sub.3--CH.sub.2--, and
--CH.sub.2--(CH.sub.2).sub.4--CH.sub.2--, each n'' is independently
selected from 4, 5, 6, 7 and 8, and m is selected from 3, 4, 5 or
6.
[0123] In certain embodiments, the cation part shown in formula (a)
is one of the following cations:
[0124] Formula (a-1): in formula (a), all the R.sup.1 is methyl,
both R.sup.2 is H, both R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, both n'' is 4, and m is 4;
[0125] Formula (a-2): in formula (a), all the R.sup.1 is methyl,
both R.sup.2 is H, both R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, both n'' is 6, and m is 4;
[0126] Formula (a-3): in formula (a), all the R.sup.1 is methyl,
both R.sup.2 is H, both R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, both n'' is 8, and m is 4;
[0127] Formula (a-4): in formula (a), all the R.sup.1 is methyl,
both R.sup.2 is H, both R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2--, both n'' is 4, and m is 6.
[0128] There is no particular restriction on the anion part of the
dual-cation fluorocarbon surfactant in the present invention;
namely, the anion may be any conventional anion in the art;
however, preferably, the anion part of the dual-cation fluorocarbon
surfactant is selected from one or more of Cl.sup.-, Br.sup.-, and
I.sup.-, more preferably is Cl.sup.- or Br.sup.-.
[0129] The present invention further provides a method for
preparing the dual-cation fluorocarbon surfactant, comprising:
subjecting the compound represented by formula (b-2) and the
compound represented by formula (b-3) to have a substitution
reaction in an alcohol solvent (e.g., mixing b-2 and b-3 and
allowing the compounds to react), wherein
##STR00032##
X is selected from halogen.
[0130] According to the present invention, the compound represented
by formula the (b-2) and the compound represented by formula the
(b-3) have a substitution reaction, so that two molecules of the
compound represented by formula the (b-2) are linked to the two
ends of a molecule of the compound represented by formula (b-3),
forming a dual-cation fluorocarbon structure with two quaternary
ammonium cations represented by formula (a).
[0131] Wherein, the compound represented by formula (b-2) and the
compound represented by formula (b-3) may be selected according to
the dual-cation fluorocarbon surfactant. They will not be detailed
any more here.
[0132] In certain embodiments, the compound represented by formula
(b-2) is selected from one or more of compounds represented by the
following formulae:
[0133] In formula (b-2-1): in formula (b-2), both R.sup.1 is
methyl, R.sup.2 is H, R.sup.3 is --CH.sub.2--CH.sub.2--CH.sub.2--,
and n'' is 4;
[0134] In formula (b-2-2): in formula (b-2), both R.sup.1 is
methyl, R.sup.2 is H, R.sup.3 is --CH.sub.2--CH.sub.2--CH.sub.2--,
and n'' is 6;
[0135] In formula (b-2-3): in formula (b-2), both R.sup.1 is
methyl, R.sup.2 is H, R.sup.3 is --CH.sub.2--CH.sub.2--CH.sub.2--,
and n'' is 8.
[0136] The compound represented by formula (b-3) is selected from
one or more of compound represented by the following formulae:
[0137] In formula (b-3-1): in formula (b-3), X is Br, and m is 4;
[0138] In formula (b-3-2): in formula (b-3), X is Br, and m is
6.
[0139] According to the present invention, the compound represented
by formula (b-2) may be a commercially available product or
prepared with a conventional method in the art. For example, the
method for preparing the compound represented by formula (b-2) may
comprise: mixing a compound represented by formula (b-4) and a
perfluoroalkyl sulfuryl fluoride compound represented by formula
(b-5) and allowing them to react accordingly in the presence of a
basic catalyst in an organic solvent, wherein
##STR00033##
The groups involved in the formulae are those as defined above, and
will not be further detailed here.
[0140] In certain embodiments, the compound represented by formula
(b-4) is selected from one or more of compounds represented by the
following formulae: [0141] In formula (b-4-1): in formula (b-4),
both R.sup.1 is methyl, R.sup.2 is H, and R.sup.3 is
--CH.sub.2--CH.sub.2--CH.sub.2-- (also referred to as
N,N-dimethyl-1,3-propylene diamine).
[0142] The perfluoroalkyl sulfuryl fluoride compound represented by
formula (b-5) is selected from one or more of compounds represented
by the following formulae: [0143] In formula (b-5-1): in formula
(b-5), n'' is 4 (also referred to as perfluorobutyl sulfuryl
fluoride); [0144] In formula (b-5-2): in formula (b-5), n'' is 6
(also referred to as perfluorohexyl sulfuryl fluoride);
[0145] In formula (b-5-3): in formula (b-5), n'' is 8 (also
referred to as perfluorooctyl sulfuryl fluoride).
[0146] Wherein, the molar ratio of the compound represented by
formula (b-4) to the perfluoroalkyl sulfuryl fluoride compound
represented by formula (b-5) may be 1:0.8-3, for example. The basic
catalyst preferably is one or more of triethylamine and/or
triethanolamine. The molar ratio of the basic catalyst to the
compound represented by formula (b-4) may be 1-3:1, for example.
The organic solvent may be one or more of dichloromethane,
dichloroethane, THF and DMF. With respect to 0.1 mol compound
represented by formula (b-4), the amount of the organic solvent
preferably is 150-300 mL. Preferably, the conditions of the contact
reaction include: reacting at 0-10.degree. C. for 30-100 min
firstly, and then reacting at 15-40.degree. C. for 3-6 h. To make
the reaction proceed more fully, preferably, the compound
represented by formula (b-4), the basic catalyst, and the organic
solvent are mixed first, and then the perfluoroalkyl sulfuryl
fluoride compound represented by formula (b-5) is introduced.
Especially, the perfluoroalkyl sulfuryl fluoride compound
represented by formula (b-5) is introduced by dropwise adding.
[0147] According to the present invention, in the method for
preparing the dual-cation fluorocarbon surfactant, preferably, the
molar ratio of the compound represented by formula (b-2) to the
compound represented by formula (b-3) is 1:1-3, more preferably is
1:1-2.
[0148] According to the present invention, the alcohol solvent may
be any solvent that can dissolve the compound represented by
formula (b-2) and can be used for the substitution reaction between
the compound represented by formula (b-2) and the compound
represented by formula (b-3), preferably is one or more of
methanol, ethanol, n-propanol, isopropanol, and n-butanol. The
amount of the alcohol solvent may vary within a wide range, as long
as the above-mentioned substitution reaction can proceed
successfully; however, to make the reaction proceed more fully and
avoid wasting the solvent, preferably, with respect to 10 mmol
compound represented by formula (b-2), the amount of the alcohol
solvent is 30-100 mL (e.g., 30-60 mL).
[0149] According to the present invention, preferably, the
conditions of the substitution reaction include: temperature of
60-100.degree. C. (preferably 70-85.degree. C.) and time of 4-10 h
(preferably 5-8 h). To make the reaction proceed more fully, the
alcohol solvent and the compound represented by formula (b-2) may
be mixed first to dissolve the compound represented by formula
(b-2) in the alcohol solvent, and then the compound represented by
formula (b-3) may be introduced to have substitution reaction.
Especially, the compound represented by formula (b-3) is introduced
into the reaction system by dropwise adding.
[0150] According to the present invention, to extract the
dual-cation fluorocarbon surfactant, the method may further
comprise: cooling the product of the substitution reaction to room
temperature (about 10-40.degree. C.), and then carrying out
solid-liquid separation, washing the solid phase, and drying the
obtained solid, so as to obtain the dual-cation fluorocarbon
surfactant.
[0151] According to the present invention, the additive composition
may further contain conventional additives used in drilling fluids
in the art; for example, the additive composition may contain one
or more of tackifier, filtrate reducer, anti-collapse agent,
filler, lubricant, and weighting agent, etc. When those additional
additives are added into a drilling fluid, it can be deemed that
the drilling fluid is formed in the form of the additive
composition in the present invention; of course, those additional
additives may also be deemed as separate components of the drilling
fluid rather than the components of the composition in the present
invention. All those cases are included in the scope of the present
invention.
[0152] The present invention further provides a water-based
drilling fluid containing the above composition.
[0153] According to the present invention, the water-based drilling
fluid (hereinafter also referred to as a pseudo oil-based drilling
fluid) that contains the additives described above in the present
invention has high temperature-resistance, plugging, and inhibition
performance, and can obtain high density, and thereby is especially
suitable for mining shale gas in complex formations. Preferably,
with respect to 100 pbw (part by weight) water in the drilling
fluid, the content of the additive composition is 20 pbw or lower,
preferably is 10 pbw or lower, more preferably is 8 pbw or lower,
further more preferably is 6 pbw or lower. On that basis, with
respect to 100 pbw water in the drilling fluid, preferably, the
content of the nano-plugging agent is 5 pbw or lower (preferably 3
pbw or lower, more preferably 2 pbw or lower, e.g., 1-2 pbw), the
content of the bionic wall bracing agent is 5 pbw or lower
(preferably 3 pbw or lower, more preferably 2 pbw or lower, further
more preferably 0.5-2 pbw, e.g., 0.5-1 pbw), the content of the
bionic shale inhibitor is 5 pbw or lower (preferably 3 pbw or
lower, more preferably 2 pbw or lower, further more preferably
0.5-2 pbw, e.g., 0.5-1 pbw), the content of the emulsifier is 1-5
pbw, and the content of the amphiphobic wettability reversal agent
is 0.1-0.5 pbw.
[0154] According to the present invention, the pseudo oil-based
drilling fluid may further contain conventional additives commonly
used in water-based drilling fluids. To obtain appropriate density,
the drilling fluid further contains a filler, which consists of
calcium carbonate of 1,600-2,500 mesh, calcium carbonate of
1,050-1,500 mesh, and calcium carbonate of 500-1,000 mesh at a
weight ratio of 1:0.5-5:0.5-5. Preferably, the filler consists of
calcium carbonate of 1,800-2,100 mesh, calcium carbonate of
1,100-1,250 mesh, and calcium carbonate of 700-900 mesh at a weight
ratio of 1:1-2:1-2. With respect to 100pbw water in the drilling
fluid, preferably the content of the filler is 1-5 pbw, more
preferably is 2-4 pbw.
[0155] According to the present invention, the pseudo oil-based
drilling fluid may contain other conventional additives commonly
used in water-based drilling fluids; preferably, the drilling fluid
further contains one or more of tackifier, filtrate reducer,
anti-collapse agent, lubricant, and weighting agent, etc.
[0156] Wherein, the tackifier can improve the viscous shearing
force of the drilling fluid. For example, the viscosity improver
may be one or more of potassium polyacrylamide (KPAM), polyanionic
cellulose (e.g., PAC141), and copolymer of acrylamide and sodium
acrylate (e.g., 80A51), preferably is potassium polyacrylamide.
With respect to 100 pbw water in the drilling fluid, preferably the
content of the tackifier is 0.1-0.5 pbw, more preferably is 0.1-0.2
pbw.
[0157] Wherein, the filtrate reducer has certain anti-collapse,
plugging, and filtrate loss reduction effects. For example, the
filtrate reducer may be one or more of modified starch and
sulfonated bitumen, etc., and preferably is modified starch. With
respect to 100 pbw water in the drilling fluid, preferably the
content of the filtrate reducer is 1-5 pbw, more preferably is 2-4
pbw.
[0158] Wherein, the anti-collapse agent can assist the bionic shale
inhibitor to prevent collapse of the well wall and improve the
stability of the well wall. For example, the anti-collapse agent
may be one or more of potassium humate (KHM), silicone (e.g.,
GF-1), and sulfonated bitumen (e.g., FT-1A), preferably is
potassium humate. With respect to 100 pbw water in the drilling
fluid, preferably the content of the anti-collapse agent is 1-5
pbw, more preferably is 2-4 pbw.
[0159] Wherein, the lubricant can improve the lubricating property
of the drilling fluid and prevent complex downhole accidents such
as jamming of a drilling tool. For example, the lubricant may be
one or more of sulfonated oil sediment (e.g., FK-10), mixture of
diesel oil and surface active agent (e.g., FRH), and mixture of
fatty glyceride and surface active agent (e.g., FK-1), preferably
is FK-10. With respect to 100 pbw water in the drilling fluid,
preferably the content of the lubricant is 1-5pbw, more preferably
is 2-4 pbw.
[0160] Wherein, the purpose of the weighting agent is to adjust the
density of the drilling fluid to required density. For example, the
weighting agent may be one or more of barite (e.g., barite with 90
wt. % or more barium sulfate) and organic salt (weigh-1, weigh-2
(the active ingredient is potassium formate), weigh-3, organic
sodium salt GD-WT), etc. With respect to 100 pbw water in the
drilling fluid, preferably the content of the weighting agent is
200-400 pbw, more preferably is 330-350 pbw.
[0161] The above additives may be commercially available products,
or may be prepared with conventional methods in the art. They will
not be further detailed hereunder.
[0162] According to the present invention, the pseudo oil-based
drilling fluid can obtain high temperature-resistance, plugging,
and inhibition performance, and can obtain high density. For
example, the drilling fluid can withstand 120.degree. C. or higher
temperature, and has 2.3 g/cm.sup.3 or higher density (the density
remains unchanged essentially after hot aging).
[0163] Hereunder the present invention will be detailed in
embodiments.
[0164] In the following embodiments and reference examples: The
weight-average molecular weight and molecular weight distribution
index are measured with a gel permeation chrommatograph (GPC) (GPC
E2695 from Waters Corporation (a US company)). The particle size
distribution of the modified silicon dioxide nano-particles
dispersed in the drilling fluid is measured with a Zeta potential
and laser particle size analyzer (from Malvern Instruments Ltd. (a
UK company)). The SEM images are obtained with a F20 Field Emission
SEM from Hitachi. The content of the copolymer chains refers to the
weight percentage of the copolymer in the obtained product. The
filler consists of calcium carbonate of 2,000 mesh, calcium
carbonate of 1,200 mesh, and calcium carbonate of 800 mesh at a
weight ratio of 1:1:1.
NANO-PLUGGING AGENT PREPARATION EXAMPLE 1
[0165] (1) 0.12 mol p-styrenesulfonic acid and 0.19 mol
N,N'-methylene-bis acrylamide (purchased from Hengtai Taili
Chemical Co., Ltd.) are mixed and stirred at about 25.degree. C.
for 30 min with 300 rpm stirring speed, and the pH of the mixture
is adjusted to 7 with sodium hydroxide; thus, a mixture A1 is
obtained; 0.5 g silicon dioxide nano-particles (purchased from
Nanjing Tianxing New Materials Co., Ltd with a trade mark TSP, in
about 20 nm particle diameter) and 8 g n-propanol are mixed and
stirred at about 25.degree. C. for 30 min with 300 rpm stirring
speed, to obtain a mixture B1; the mixture A1 and the mixture B1
are mixed and stirred at about 25.degree. C. for 30 min with 300
rpm stirring speed, to obtain a mixture C1; [0166] (2) 0.01 g
coupler .gamma.-aminopropyl-triethoxysilane (purchased from Hengtai
Taili Chemical Co., Ltd. with a trade mark KH550) and the mixture
C1 are mixed and react at 60.degree. C. for 30 min while stirring
at 200 rpm stirring speed; then, 0.094 g redox initiator system
(consisting of sodium bisulfite and ammonium persulfate at 1:2.5
molar ratio) is added, and then the mixture takes a polymerization
reaction at 60.degree. C. for 4 h while stirring at 200 rpm
stirring speed; [0167] (3) The product of the polymerization
reaction is dried at 70.degree. C. over night (about 24 h), and
then is milled; thus, modified silicon dioxide nano-particles S1
are obtained. [0168] Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the modified silicon dioxide
nano-particles Si bear random copolymer chains composed of
structural units represented by formula (1-a) (R.sup.8 is
--SO.sub.3H, R.sup.6--R.sup.7 and R.sup.9--R.sup.10 are H, and L'
is C0 alkylene) and structural units represented by formula (2-a)
(L is --CH.sub.2--) at 1:1.5 molar ratio, the content of the
copolymer chain is 92 wt. %, and the weight-average molecular
weight of the copolymer chain is about 860,000 g/mol; the particle
diameter of the modified silicon dioxide nano-particles S1 is about
26 nm. An SEM image of the modified silicon dioxide nano-particles
S1 is shown in FIG. 1.
NANO-PLUGGING AGENT PREPARATION EXAMPLE 2
[0168] [0169] (1) 0.15 mol p-styrenesulfonic acid and 0.2 mol
N,N'-methylene-bis acrylamide (purchased from Hengtai Taili
Chemical Co., Ltd.) are mixed and stirred at about 30.degree. C.
for 25 min with 250 rpm stirring speed, and the pH of the mixture
is adjusted to 7.5 with sodium hydroxide; thus, a mixture A2 is
obtained; 1 g silicon dioxide nano-particles (purchased from
Nanjing Tianxing New Materials Co., Ltd with a trade mark TSP, in
about 20 nm particle diameter) and 8 g isopropanol are mixed and
stirred at about 30.degree. C. for 25 min with 250 rpm stirring
speed, to obtain a mixture B2; the mixture A2 and the mixture B2
are mixed and stirred at about 30.degree. C. for 25 min with 250
rpm stirring speed, to obtain a mixture C2; [0170] (2) 0.012 g
coupler .gamma.-aminopropyl-triethoxysilane (purchased from Hengtai
Taili Chemical Co., Ltd. with a trade mark KH550) and the mixture
C2 are mixed and react at 50.degree. C. for 30 min while stirring
at 250 rpm stirring speed; then, 0.094 g redox initiator system
(consisting of sodium bisulfite and ammonium persulfate at 1:3
molar ratio) is added, and then the mixture takes a polymerization
reaction at 50.degree. C. for 5 h while stirring at 200 rpm
stirring speed; [0171] (3) The product of the polymerization
reaction is dried at 70.degree. C. over night (about 24 h), and
then is milled; thus, modified silicon dioxide nano-particles S2
are obtained. [0172] Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the modified silicon dioxide
nano-particles S2 bear random copolymer chains composed of
structural units represented by formula (1-a) (R.sup.8 is
--SO.sub.3H, R.sup.6-R.sup.7 and R.sup.9-R.sup.10 are H, and L' is
C0 alkylene) and structural units represented by formula (2-a) (L
is --CH.sub.2--) at 1:1.33 molar ratio, the content of the
copolymer chain is 94 wt. %, and the weight-average molecular
weight of the copolymer chain is about 980,000 g/mol; the particle
diameter of the modified silicon dioxide nano-particles S2 is about
23 nm.
COMPARATIVE NANO-PLUGGING AGENT PREPARATION EXAMPLE 1
[0172] [0173] The method described in the nano-plugging agent
preparation example 1 is used, but N,N'-methylene-bis acrylamide is
not added in the step (1), and the amount of p-styrenesulfonic acid
is increased to 0.3 mol; thus, modified silicon dioxide
nano-particles DS1 are prepared through three steps.
[0174] Analyzed by infrared, .sup.1H-NMR and .sup.13C-NMR
spectroscopy, the modified silicon dioxide nano-particles DS1 bear
polymer chains composed of structural units represented by formula
(1-a) (R.sup.8 is --SO.sub.3H, R.sup.6-R.sup.7 and R.sup.9-R.sup.10
are H, and L' is CO alkylene), the content of the polymer chain is
98 wt. %, and the weight-average molecular weight of the polymer
chain is about 1,500,000 g/mol; the particle diameter of the
modified silicon dioxide nano-particles DS1 is about 50 nm.
COMPARATIVE NANO-PLUGGING AGENT PREPARATION EXAMPLE 2
[0175] The method described in the nano-plugging agent preparation
example 1 is used, but p-styrenesulfonic acid is not added in the
step (1), and the amount of N,N'-methylene-bis acrylamide is
increased to 0.3 mol; thus, modified silicon dioxide nano-particles
DS2 are prepared through three steps. [0176] Analyzed by infrared,
.sup.1H-NMR and .sup.13C-NMR spectroscopy, the modified silicon
dioxide nano-particles DS2 bear polymer chains composed of
structural units represented by formula (2-a) (L is --CH.sub.2--),
the content of the polymer chain is 96 wt. %, and the
weight-average molecular weight of the polymer chain is about
120,000g/mol; the particle diameter of the modified silicon dioxide
nano-particles DS2 is about 42 nm.
BIONIC WALL BRACING AGENT PREPARATION EXAMPLE 1
[0176] [0177] (1) 1,000 kg deionized water is loaded into a
container, 50 kg carboxymethyl chitosan (purchased from Beijing
datianfengtuo Chemical Technology Co., Ltd., having a structure
represented by formula (III), weight-average molecular
weight=52,000 g/mol, degree of carboxymethyl substitution=1.4) is
added into the container while stirring (at 200 rpm stirring
speed), and the mixture is further stirred till the carboxymethyl
chitosan is dissolved fully and there is no flocculent solid
suspending in the solution). [0178] (2) 50 kg acrylic acid is added
into the water solution of carboxymethyl chitosan, the solution is
stirred for 5 min, and then 2 kg nitric acid is added and the
solution is stirred further for 5 min, till the carboxymethyl
chitosan, acrylic acid and nitric acid solution are mixed to a
homogeneous state. Then, 4 kg ammonium ceric nitrate is added, and
the solution is stirred till the ammonium ceric nitrate is fully
dissolved. Next, the reaction system is heated up to 70.degree. C.,
and timing is started once the temperature in the reactor reaches
70.degree. C.; after 4 h reaction, the reactor is cooled to
25.degree. C. The product in the first stage shall be straw yellow
transparent liquid. [0179] (3) 5 kg
1-ethyl-3-(3-dimethyllaminopropyl) carbonyl diimine hydrochlide is
added into the reaction system after cooling (5 kg
1-ethyl-3-(3-dimethyllaminopropyl) carbonyl diimine hydrochlide is
divided into 5 parts, the reaction system is stirred for 15 min
whenever a part is added, and then the next part is added, and so
on, till all parts are added). Then, the solution is stirred for 12
h at room temperature, till the 1-ethyl-3-(3-dimethyllaminopropyl)
carbodiie hydrochlide is dissolved fully. The product is still
straw yellow transparent solution. [0180] (4) 5 kg dopamine
hydrochloride is added into the system after the
1-ethyl-3-(3-dimethyllaminopropyl) carbonyl diimine hydrochlide is
dissolved, and the system is stirred for 24 h at room temperature
for reaction, till a final reaction product bionic wall bracing
agent GBFS-1 is generated. The product is straw yellow liquid that
has certain viscosity. It is tested that the weight-average
molecular weight of the reaction product bionic wall bracing agent
GBFS-1 is 84,320 g/mol.
BIONIC SHALE INHIBITOR PREPARATION EXAMPLE 1
[0180] [0181] 0.5 mol (87.1 g) L-arginine and 0.2 mol (29.2 g)
L-lysine are mixed and stirred at 195.degree. C., 1.75 mol (171.5
g) phosphoric acid (85 wt. % phosphoric acid solution) is added
into the mixture, and the mixture is held at 195.degree. C. for 16
h for reaction. After the reaction is completed, 200 g water is
added when the temperature drops to about 120.degree. C., and then
the mixture is stirred further for 20 min, till the product is
fully dissolved in the water. Next, the water solution of the
reaction product is taken out, and dried at about 120.degree. C. to
obtain solid; next, the solid is dissolved in dimethyl sulfoxide,
and the insoluble substance is separated from the solution by
suction filtration. Then, the solution is evaporated by rotary
evaporation; thus, 91.8 g bionic shale inhibitor YZFS-1 is
obtained. Measured by gel permeation chromatography, the
weight-average molecular weight Mw is 1,551 g/mol, and the
molecular weight distribution index is 1.465. Analyzed by
.sup.1H-NMR and .sup.13C-NMR spectroscopy, the molar ratio of the
structural units represented by formula (3) to the structural units
represented by formula (4) in the obtained polymer is 2.47:1.
EMULSIFIER PREPARATION EXAMPLE 1
[0181] [0182] (1) The reactants are mixed at a molar ratio of
tetraethylene pentamine to linoleic acid=1:2.2 (i.e., the molar
ratio of tetraethylene pentamine calculated by primary amine group
to linoleic acid is 1:1.1), and stirred for 40 min At 250 r/min
Stirring speed, then the pH of the obtained mixture is adjusted to
9, and the mixture is kept at 230.degree. C. for reaction of 3 h,
while water is separated with a water separator in the process,
next, the product is cooled to room temperature; [0183] (2) The
reaction product in the step (1) is mixed with propandioic acid
(the molar ratio of the tetraethylene pentamine to the propandioic
acid is 1:0.6), then the pH of the obtained mixture is adjusted to
8, next, the mixture is stirred at 400 r/min at 90.degree. C. for 6
h; thus, an emulsifier E1 is obtained. Detected and analyzed by
infrared spectroscopy, .sup.1H-NMR and .sup.13C-NMR spectroscopy,
the emulsifier E1 contains amido groups, unsaturated double bonds,
and carboxyl groups, and is in a comb structure.
REVERSAL AGENT INTERMEDIATE PREPARATION EXAMPLE 1
[0183] [0184] 0.12 mol N,N'-dimethyl-1,3-propylene diamine is
dissolved in 250 mL dichloromethane at 0-5.degree. C., 0.12 mol
triethylamine is added, and the mixture is mixed and stirred for 30
min; then, 0.1 mol perfluoro-butyl sulfuryl fluoride is added by
dropwise adding at 0-5.degree. C. (added completely within about 30
min, purchased from Hubei Jusheng Technology Co., Ltd. with a trade
mark 375-72-4), and the mixture is held at 0-5.degree. C. for 60
min for reaction, and then is held at 25.degree. C. for 4 h for
reaction; the obtained product is filtered, the filter cake is
washed with dichloromethane, dried, and then recrystallized with
acetone; thus, 128.7 g white solid is obtained. Analysis by
infrared, .sup.1H-NMR and .sup.13C-NMR spectroscopy, the solid is
the compound represented by formula (b-2-1).
REVERSAL AGENT INTERMEDIATE PREPARATION EXAMPLE 2
[0184] [0185] 0.12 mol N,N'-dimethyl-1,3-propylene diamine is
dissolved in 250 mL dichloromethane at 0-5.degree. C., 0.12 mol
triethylamine is added, and the mixture is mixed and stirred for 30
min; then, 0.1 mol perfluoro-hexyl sulfuryl fluoride is added by
dropwise adding at 0-5.degree. C. (added completely within about 30
min, purchased from Hubei xinmingtai Chemical Co., Ltd. with a
trade mark 423-50-7), and the mixture is held at 0-5.degree. C. for
60 min For reaction, and then is held at 25.degree. C. for 4 h for
reaction; the obtained product is filtered, the filter cake is
washed with dichloromethane, dried, and then recrystallized with
acetone; thus, 125.3 g white solid is obtained. Analysis by
infrared, .sup.1H-NMR and .sup.13C-NMR spectroscopy, the solid is
the compound represented by formula (b-2-2).
REVERSAL AGENT INTERMEDIATE PREPARATION EXAMPLE 3
[0185] [0186] 0.12 mol N,N'-dimethyl-1,3-propylene diamine is
dissolved in 300 ml dichloromethane at 0-5.degree. C., 0.12 mol
triethylamine is added, and the mixture is mixed and stirred for 30
min; then, 0.1 mol perfluoro-octyl sulfuryl fluoride is added by
dropwise adding at 0-5.degree. C. (added completely within about 30
min, purchased from Shanghai Yijing Industrial Co., Ltd. with a
trade mark 307-35-7), and the mixture is held at 0-5.degree. C. for
60 min for reaction, and then is held at 25.degree. C. for 4 h for
reaction; the obtained product is filtered, the filter cake is
washed with dichloromethane, dried, and then recrystallized with
acetone; thus, 127.4 g white solid is obtained. Analysis by
infrared, .sup.1H-NMR and .sup.13C-NMR spectroscopy, the solid is
the compound represented by formula (b-2-3).
AMPHIPHOBIC WETTABILITY REVERSAL AGENT PREPARATION EXAMPLE 1
[0186] [0187] 10 mmol compound represented by formula (b-2-1) is
dissolved in 50 mL ethanol at 65.degree. C., and then 11 mmol
1,4-dibromobutane is added by dropwise adding (added completely
within about 20 min), and the mixture is stirred for 6 h at
75.degree. C. for reaction; the reaction product is cooled to room
temperature (about 25.degree. C.) for crystallization, and then is
filtered, and the filter cake is washed and dried; thus, 12.34 g
solid is obtained. Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the solid is the amphiphobic wettability
reversal agent RA1 in which the groups represented by formula (a-1)
are cations and bromine ions are anions.
AMPHIPHOBIC WETTABILITY REVERSAL AGENT PREPARATION EXAMPLE 2
[0187] [0188] 10 mmol compound represented by formula (b-2-2) is
dissolved in 50 mL ethanol at 65.degree. C., and then 11 mmol
1,4-dibromobutane is added by dropwise adding (added completely
within about 20 min), and the mixture is stirred for 6 h at
75.degree. C. for reaction; the reaction product is cooled to room
temperature (about 25.degree. C.) for crystallization, and then is
filtered, and the filter cake is washed and dried; thus, 12.43 g
solid is obtained. Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the solid is the amphiphobic wettability
reversal agent RA2 in which the groups represented by formula (a-2)
are cations and bromine ions are anions.
AMPHIPHOBIC WETTABILITY REVERSAL AGENT PREPARATION EXAMPLE 3
[0188] [0189] 10 mmol compound represented by formula (b-2-3) is
dissolved in 60 mL isopropanol at 55.degree. C., and then 12 mmol
1,4-dibromobutane is added by dropwise adding (added completely
within about 20 min), and the mixture is stirred for 7 h at
85.degree. C. for reaction; the reaction product is cooled to room
temperature (about 25.degree. C.) for crystallization, and then is
filtered, and the filter cake is washed and dried; thus, 12.54 g
solid is obtained. Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the solid is the amphiphobic wettability
reversal agent RA3 in which the groups represented by formula (a-3)
are cations and bromine ions are anions.
AMPHIPHOBIC WETTABILITY REVERSAL AGENT PREPARATION EXAMPLE 4
[0189] [0190] The method described in the amphiphobic wettability
reversal agent preparation example 1 is used, but
1,6-dibromo-hexane is used in replacement of 1,4-dibromobutane;
finally, 11.87 g solid is obtained. Analyzed by infrared,
.sup.1H-NMR and .sup.13C-NMR spectroscopy, the solid is the
amphiphobic wettability reversal agent RA4 in which the groups
represented by formula (a-4) are cations and bromine ions are
anions.
COMPARATIVE AMPHIPHOBIC WETTABILITY REVERSAL AGENT PREPARATION
EXAMPLE 1
[0190] [0191] 10 mmol compound represented by formula (b-2-3) is
dissolved in 50 mL ethanol at 65.degree. C., and then 11 mmol
sodium 2-hydroxy-3-chloropropanesulfonate is added by dropwise
adding (added completely within about 20 min), the pH is adjusted
to 9 with sodium hydroxide solution, and the mixture is stirred for
6 h at 85.degree. C. for reaction; the reaction product is cooled
to room temperature (about 25.degree. C.) for crystallization, and
then is filtered, and the filter cake is washed and dried; thus,
10.54 g solid is obtained. Analyzed by infrared, .sup.1H-NMR and
.sup.13C-NMR spectroscopy, the solid is amphiphobic wettability
reversal agent DRA1 represented by formula
##STR00034##
[0192] Test Case 1 [0193] 1. Measurement of amphiphobic property of
rock surface: [0194] 1 wt. % water solution of the amphiphobic
wettability reversal agent is prepared as the fluid to be tested, 1
wt. % water solution of hexadecyl trimethyl ammonium bromide is
prepared (as a comparative amphiphobic wettability reversal agent
DRA2), 1 wt. % water solution of alkyl polyoxyethylene ether
sulfate (purchased from Jiangsu Haian Petrochemical Plant) is
prepared (as a comparative amphiphobic wettability reversal agent
DRA3), and 1 wt. % water solution of nonyl phenol polyoxyethylene
ether (purchased from Jiangsu Haian Petrochemical Plant) is
prepared (as a comparative amphiphobic wettability reversal agent
DRA4), respectively, and an artificial rock core is immersed in
each of the solution for 8 h at 160.degree. C.; the rock cores are
taken out, and cooled and dried naturally, and then the contact
angles .theta..sub.o and .theta..sub.w of oil phase and water phase
on the surfaces of rock cores are measured with a contact angle
meter (JC2000D3 contact angle meter from Shanghai Zhongchen Digital
Technology and Equipment Co., Ltd.). The results are shown in Table
1, wherein, the oil phase test liquid is n-hexadecane, and the
water phase test liquid is distilled water. [0195] 2. Surface
tension test: [0196] The surface tension is measured with a TX-500C
full-range spinning drop interfacial tensiometer with a spinning
drop method. The main process of the spinning drop method includes:
the liquid to be tested is added in an appropriate amount into a
sample tube (the above-mentioned amphiphobic wettability reversal
agent and the amphiphobic wettability reversal agents in the
comparative examples are dissolved in distilled water to prepare
solutions at different concentrations, see table 1 for the
details), a bubble in appropriate size is squeezed into the sample
tube, so that gas and liquid phases are formed in the sample tube;
then, the sample tube is centrifuged at a high rotation speed
.omega.=7,000 r/min, so that the low-density bubble is elongated in
the high-density solution under the actions of centrifugal force,
gravity, and interfacial tension. The diameter of the elongated
bubble is measured, and the surface tension in the state is
calculated from the diameter and the given difference in density
between the two phases; in addition, the measurement temperature is
25.degree. C. The results are shown in Table 1. [0197] 3. Influence
of wettability on dynamic capillary spontaneous imbibition [0198] A
SWT rock core spontaneous water imbibition evaluation system from
Jingzhou Modern Oil Technology Development Co., Ltd. is used,
liquid-wetted rock core columns and gas-wetted rock core columns
are prepared from dense rock cores with similar permeability
respectively (the mass fraction of the amphiphobic wettability
reversal agent is 2 wt. % in the treatment), and a spontaneous
imbibition test is carried out at room temperature (about
25.degree. C.); in the test, air is the gas phase, and saline water
and kerosene are liquid phases, wherein, the saline water is 12 wt.
% NaCl solution (with 1.07 g/cm.sup.3 density), the density of
kerosene is 0.78 g/cm.sup.3. The dynamic conditions of spontaneous
oil and water imbibition of the rock cores and the final degree of
liquid saturation from spontaneous imbibition are logged
respectively, and the gas permeability of the rock cores after
spontaneous imbibition is tested (see Table 2 for the results).
TABLE-US-00001 [0198] TABLE 1 Surface tension at different
Amphiphobic concentrations (mN/m) wettability 0.05 0.10 0.20
reversal agent .theta..sub.w/(.degree.) .theta..sub.o/(.degree.)
wt. % wt. % wt. % Distilled water 0 0 / / / RA1 102.56 75.99 16.4
16.4 16.4 RA2 104.32 74.68 16.5 16.4 16.4 RA3 103.21 73.86 16.4
16.5 16.4 RA4 105.02 75.45 16.5 16.4 16.5 DRA1 92.56 69.12 20.2
20.2 20.1 DRA2 76.23 48.82 38.1 38.2 38.1 DRA3 75.66 49.54 38.2
38.1 38.1 DRA4 77.14 49.08 38.1 38.1 38.1
[0199] It is seen from the results in Table 1: the amphiphobic
wettability reversal agent provided in the present invention makes
the rock surface amphiphobic, wherein, the water wetting angle is
up to 100.degree. or above, and the n-hexadecane wetting angle is
up to 70.degree. or above; in addition, the surface tension is
decreased.
TABLE-US-00002 TABLE 2 Agent V.sub.p m.sub.0 Liquid m(single)
s(single) m(reverse) s(reverse) Blank 1.875 69.38 Saline 70.55
62.47 70.90 81.12 water 1.757 68.69 Kerosene 69.53 59.75 69.81
79.43 RA1 1.744 68.53 Saline 68.79 18.84 68.90 26.34 water 1.704
68.07 Kerosene 68.31 17.24 68.51 32.16 RA2 1.742 68.51 Saline 68.83
18.62 68.87 26.03 water 1.704 68.05 Kerosene 68.28 17.12 68.49
31.95 RA3 1.748 68.51 Saline 68.77 18.89 68.88 26.41 water 1.706
68.05 Kerosene 68.29 17.28 68.49 32.22 RA4 1.738 68.42 Saline 68.68
18.76 68.78 26.25 water 1.702 68.02 Kerosene 68.25 17.18 68.46
32.13 DRA1 1.756 68.52 Saline 68.80 19.79 69.03 36.45 water 1.712
68.12 Kerosene 68.37 18.16 68.71 42.83 DRA2 1.795 68.84 Saline
69.22 26.44 69.39 38.21 water 1.722 68.47 Kerosene 68.81 24.95
69.07 43.48 DRA3 1.798 68.84 Saline 69.22 26.43 69.38 37.46 water
1.722 68.46 Kerosene 68.80 24.93 69.05 43.04 DRA4 1.798 68.84
Saline 69.22 26.45 69.38 37.47 water 1.724 68.46 Kerosene 68.80
24.94 69.05 43.03 Note: "blank" represents no amphiphobic agent;
"V.sub.p" represents volume of permeation; "m.sub.0" represents
mass of permeation; "m(single)" represents rock core mass after
spontaneous imbibition in single direction; "s(single)" represents
degree of liquid saturation in the rock core after spontaneous
imbibition in single direction; "m(reverse)" represents rock core
mass after spontaneous imbibition in reverse direction;
"s(reverse)" represents degree of liquid saturation in the rock
core after spontaneous imbibition in reverse direction.
[0200] It is seen from Table 2: after the dual-cation fluorocarbon
surfactant obtained in the present invention is added as an
amphiphobic wettability reversal agent, all of the "V.sub.p",
"M.sub.0", "m(single)", "s(single)", "m(reverse)", and "s(reverse)"
are decreased, indicating that the dual-cation fluorocarbon
surfactant obtained in the present invention has a favorable
amphiphobic effect.
EXAMPLE 1
[0201] This exmaple is provided to describe the additive
composition and the pseudo oil-based drilling fluid in the present
invention.
[0202] The formulation is: 100 pbw water, 2 pbw modified silicon
dioxide nano-particle S1, 1 pbw bionic wall bracing agent GBFS-1, 1
pbw bionic shale inhibitor YZFS-1, 3 pbw emulsifier E1, 0.1 pbw
amphiphobic wettability reversal agent RA1, 3 pbw filler, 0.2 pbw
potassium polyacrylamide (K-PAM purchased from Renqiu Hongze
petrochemical industry Co., Ltd., the same below), 3 pbw modified
starch (LYS purchased from Shandung Deshunyuan Petroleum Sci. &
Tech. Co., Ltd., the same below), 3 pbw potassium humate (KHM
purchased from Beijing Shida Bocheng Technology Co., Ltd.), 15 pbw
organic salt (GD-WT organic sodium salt purchased from Hebei
Guangda Petrochemical Co., Ltd., the same below), 2 pbw lubricant
(trade mark FHGT-G modified phospholipid purchased from Shanghai
Youchuang Industrial Co., Ltd.), 330 pbw barite (ZR-43 barite
purchased from Sichuan Zhengrong Industrial Co., Ltd.); thus, a
drilling fluid Y1 is prepared.
EXAMPLE 2
[0203] This exmaple is provided to describe the additive
composition and the pseudo oil-based drilling fluid in the present
invention.
[0204] The formulation described in the example 1 is used, but
modified silicon dioxide nano-particles S2 are used in replacement
of the modified silicon dioxide nano-particles S1; thus, a drilling
fluid Y2 is prepared.
EXAMPLE 3
[0205] This exmaple is provided to describe the additive
composition and the pseudo oil-based drilling fluid in the present
invention.
[0206] The formulation described in the example 1 is used, but the
amount of the modified silicon dioxide nano-particle S1 is 1 pbw,
the amount of the bionic wall bracing agent GBFS-1 is 2 pbw, and
the amount of the bionic shale inhibitor YZFS-1 is 2 pbw; thus, a
drilling fluid Y3 is prepared.
COMPARATIVE EXAMPLE 1
[0207] The formulation described in the example 1 is used, but the
modified silicon dioxide nano-particles DS1 are used in replacement
of the modified silicon dioxide nano-particles S1, and the
emulsifier E1 and amphiphobic wettability reversal agent RA1 are
not used; thus, a drilling fluid DY1 is prepared.
COMPARATIVE EXAMPLE 2
[0208] The formulation described in the example 1 is used, but the
modified silicon dioxide nano-particles DS2 are used in replacement
of the modified silicon dioxide nano-particles S1, and the
emulsifier E1 and amphiphobic wettability reversal agent RA1 are
not used; thus, a drilling fluid DY2 is prepared.
COMPARATIVE EXAMPLE 3
[0209] The formulation described in the example 1 is used, but
unmodified silicon dioxide nano-particles (TSP purchased from
Nanjing Tianxing New Materials Co., Ltd., the particle diameter is
about 20 nm) are used in replacement of the modified silicon
dioxide nano-particles S1, and the emulsifier E1 and amphiphobic
wettability reversal agent RA1 are not used; thus, a drilling fluid
DY3 is prepared.
COMPARATIVE EXAMPLE 4
[0210] The formulation described in the example 1 is used, but the
bionic wall bracing agent GBFS-1, emulsifier E1 and amphiphobic
wettability reversal agent RA1 are not used; thus, a drilling fluid
DY4 is prepared.
COMPARATIVE EXAMPLE 5
[0211] The formulation described in the example 1 is used, but 1
pbw small cations (CSM-1 purchased from Tianjian Petroleum
Technology Co., Ltd.) are used in replacement of the bionic shale
inhibitor YZFS-1, and the emulsifier E1 and amphiphobic wettability
reversal agent RA1 are not used; thus, a drilling fluid DY5 is
prepared.
Test Case 2
[0212] Testing basic properties of the drilling fluids: the
drilling fluids Y1-Y3 and DY1-DY5 are tested at room temperature
without hot aging and after hot aging at 120.degree. C. for 16 h
respectively, to test their plastic viscosity (PV), apparent
viscosity (AV), yield point (YP), ratio of yield point to plastic
viscosity, gel strength (GEL, i.e., initial gel strength/final gel
strength), API filtration (API), high-temperature and high-pressure
filtration (HTHL), density, and ph. The results are shown in Table
3, wherein:
[0213] The plastic viscosity (PV) is measured with a FANN six-speed
viscosity meter with the method specified in the national standard
GB/T29170-2012, in unit of mpas,
PV=.theta..sub.600-.theta..sub.300.
[0214] The apparent viscosity (AV) is measured with a FANN
six-speed viscosity meter with the method specified in the national
standard GB/T29170-2012, in unit of mpas, AV=1/2.theta..sub.600.
[0215] The yield point (YP) is measured with a FANN six-speed
viscosity meter with the method specified in the national standard
GB/T29170-2012, YP=0.511.times.(2.times..phi.300-.phi.600), in unit
of Pa. The ratio of yield point to plastic viscosity is
[0215] YP .PHI.600 - .PHI.300 , ##EQU00001##
where, .phi.600 and .phi.300 are read with a six-speed viscosity
meter in sequence.
[0216] The GEL strength refers to the strength of the gel structure
formed after the drilling fluid enters into a still state, i.e.,
the ratio of initial gel strength to final gel strength, in unit of
Pa/Pa; wherein, the initial gel strength and final gel strength are
measured with a FANN six-speed viscosity meter with the method
specified in the national standard GB/T29170-2012: [0217]
Initial_Gel_Strength=0.511.theta..sub.3(10 s) [0218]
Final_Gel_Strength=0.511.theta..sub.3(10 min).
[0219] API refers to intermediate pressure filter loss, and is
measured with an API filter loss meter with the method specified in
the standard SY/T5621-93, in unit of mL. [0220] HTHP refers to
high-temperature and high-pressure filter loss, and is measured
with a HTHP filter loss meter with the method specified in the
national standard GB/T29170-2012, in unit of mL.
TABLE-US-00003 [0220] TABLE 3 Ratio of yield point to Drilling AV
PV YP plastic GEL API HTHP Density Fluid mPa s mPa s Pa viscosity
Pa/Pa mL mL g/cm.sup.3 pH Before hot aging Y1 122 101 21 0.21 4/19
/ / 2.3 9 Y2 119 103 16 0.26 4.5/17 / / 2.3 9 Y3 120 102 18 0.22
4/18 / / 2.3 9 DY1 126 114 12 0.11 4/23 / / 2.3 9 DY2 130 118 12
0.10 4/22 / / 2.30 9 DY3 138 128 10 0.08 5/23 / / 2.30 9 DY4 115
103 12 0.12 3/18 / / 2.3 9 DY5 116 104 12 0.12 3/17 / / 2.3 9 After
hot aging at 120.degree. C. for 16 h Y1 103 87 16 0.18 3/14 0.6 3.0
2.31 9 Y2 102 85 17 0.2 3/13 0.4 2.8 2.31 9 Y3 102 86 16 0.19 3/13
0.7 3.0 2.31 9 DY1 103 92 11 0.12 3.5/15 1.2 6.0 2.31 9 DY2 105 95
10 0.11 4/15 1.2 6.8 2.32 9 DY3 107 98 9 0.09 4/16 1.6 8.4 2.32 9
DY4 96 86 10 0.12 3/14 1.0 5.2 2.31 9 DY5 95 86 9 0.10 3/12 1.4 6.2
2.31 9 Note: "/" represents "not tested".
[0221] It is seen from Table 3: though the density is high and the
system has high barite content, the drilling fluid system provided
in the present invention still has a good ratio of yield point to
plastic viscosity, and both the API filter loss and the HTHP filter
loss are low. However, in case the nano-plugging agent, bionic wall
bracing agent and bionic inhibitor in the drilling fluid system are
replaced and the emulsifier and amphiphobic wettability reversal
agent are not used, the ratio of yield point to plastic viscosity
of the obtained drilling fluid system (e.g., reference examples
DY1-DY5) begin to decrease, indicating that the rheological
property of the system becomes poor; in addition, the API filter
loss and HTHP filter loss become higher, which is adverse to well
wall stability.
Test Case 3
[0222] The steps of hot-aging recovery rate test are mainly as
follows:350 mL test solution (tap water and above-mentioned
drilling fluids respectively) is loaded into an aging can, 50 g mud
shale debris of 6-10 mesh is weighed, loaded into a roller hearth,
and rolled at 120.degree. C. for 16 h for dispersion; then, the
recovered rock sample is screen through a 40 mesh screen in water
to clean state, and the residual rock sample is loaded into a watch
glass, and then is dried in an oven at 105.degree. C. to constant
weight; the weight is measured, and the hot-aging recovery rate is
calculated with the following formula (the result is shown in Table
4):
S=M/50.times.100%
where, S--recovery rate after screening through a 40 mesh screen,
%; M--screen residue after screening though the 40 mesh screen,
g.
TABLE-US-00004 TABLE 4 Test solution Hot-aging recovery rate/% Tap
water 18.62 Drilling fluid Y1 99.44 Drilling fluid Y2 99.32
Drilling fluid Y3 99.57 Drilling fluid DY1 91.68 Drilling fluid DY2
92.12 Drilling fluid DY3 90.56 Drilling fluid DY4 74.18 Drilling
fluid DY5 80.56
[0223] It is seen from Table 4: with the drilling fluid system
provided in the present invention, all of the hot-aging recovery
rates of rock cuttings are 99% or higher, indicating the system has
a good inhibition effect against mud shale; in case the
nano-plugging agent, bionic wall bracing agent and bionic inhibitor
in the drilling fluid system are replaced and the emulsifier and
amphiphobic wettability reversal agent are not used, the hot-aging
recovery rates attained with the obtained drilling fluid systems
(e.g., reference examples DY1-DY5) are severely decreased, and the
inhibition performance is poor.
Test Case 4
[0224] The swelling property is measured with a dual-channel shale
swelling tester with the method specified in SY/T5613-2000. The
result is shown in Table 5. The steps of the test are mainly as
follows: [0225] 1. Preparation of rock core: 10 g sodium bentonite
dried at 105.degree. C..+-.2.degree. C. is weighed and loaded into
a test cylinder, and a plug rod is inserted into the test cylinder
and held for 5 min at 10 MPa pressure. [0226] 2. Blank test: the
test cylinder with the rock core is mounted on the shale swelling
tester, distilled water is injected into the test cylinder, and the
rock core is soaked for 16 h. The linear swelling amount of the
rock core is logged. [0227] 3. Measurement with test solution: the
test cylinder with the rock core is mounted on the shale swelling
tester, 20 mL drilling fluid is injected into the test cylinder,
and the rock core is soaked for 16 h. The linear swelling amount of
the rock core is logged, and the reduced rate of linear swelling is
calculated with formula
[0227] B = .DELTA. H 1 - .DELTA. H 2 .DELTA. H 1 .times. 100 % ,
##EQU00002##
where, B--reduced rate of linear swelling of rock core, in unit of
percent (%); .DELTA.H.sub.1--linear swelling amount of the rock
core after soaked in distilled water for 16 h (i.e., increased
height of rock core), in unit of millimeter (mm); [0228]
.DELTA.H.sub.2--linear swelling amount of the rock core after
soaked in the test solution for 16 h (i.e., increased height of
rock core), in unit of millimeter (mm).
TABLE-US-00005 [0228] TABLE 5 Increased height Reduced rate of Test
solution of rock core/mm linear swelling/% Tap water 8.76 /
Drilling fluid Y1 0.72 91.78 Drilling fluid Y2 0.74 91.55 Drilling
fluid Y3 0.69 92.12 Drilling fluid DY1 1.22 84.51 Drilling fluid
DY2 1.32 84.93 Drilling fluid DY3 1.43 83.68 Drilling fluid DY4
2.17 75.23 Drilling fluid DY5 1.98 77.4
[0229] It is seen from Table 5: with the drilling fluid system
provided in the present invention, all of the reduced rates of
linear swelling are 90% or higher, indicating the system has a good
inhibition effect; when the nano-plugging agent, bionic wall
bracing agent and bionic inhibitor in the drilling fluid system are
replaced and the emulsifier and hydrophobic and oileophobic
wettability reversal agent are not reused, the swelling inhibition
index of the obtained drilling fluid systems (e.g., reference
examples DY1-DY5) is severely compromised, and the inhibition
performance is poor.
[0230] While some preferred embodiments of the present invention
are described above, the present invention is not limited to the
details in those embodiments. Those skilled in the art can make
modifications and variations to the technical scheme of the present
invention, without departing from the spirit of the present
invention. However, all these modifications and variations shall be
deemed as falling into the protected scope of the present
invention.
[0231] In addition, it should be noted that the specific technical
features described in above embodiments can be combined in any
appropriate form, provided that there is no conflict. To avoid
unnecessary repetition, the possible combinations are not described
specifically in the present invention.
[0232] Moreover, different embodiments of the present invention can
be combined freely as required, as long as the combinations don't
deviate from the ideal and spirit of the present invention.
However, such combinations shall also be deemed as falling into the
scope disclosed in the present invention.
* * * * *