U.S. patent application number 16/130694 was filed with the patent office on 2019-03-21 for film former used for coal-bed gas well drilling and preparation method thereof, drilling fluid and usage thereof.
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 Deli GAO, Liexiang HAN, Yinbo HE, Guancheng JIANG, Yanjun LI, Zhong LI, Fan LIU, Chunyao PENG, Xiangzeng WANG, Yong WANG, Xianzhu WU, Lili YANG, Shuo ZHANG, Yongqing ZHANG, Hongguo ZUO.
Application Number | 20190085231 16/130694 |
Document ID | / |
Family ID | 61061451 |
Filed Date | 2019-03-21 |
United States Patent
Application |
20190085231 |
Kind Code |
A1 |
JIANG; Guancheng ; et
al. |
March 21, 2019 |
FILM FORMER USED FOR COAL-BED GAS WELL DRILLING AND PREPARATION
METHOD THEREOF, DRILLING FLUID AND USAGE THEREOF
Abstract
The present invention relates to the well drilling field in the
petroleum industry, particularly to film former used for coal-bed
gas well drilling and preparation method thereof, drilling fluid
and usage thereof. The preparation method of the film former
includes: (1) controlling polycaprolactone diol and diisocyanate to
have a first polymerization reaction in the presence of a
polyurethane catalyst, to obtain a polyurethane prepolymer with two
ends blocked by diisocyanate; (2) controlling the product of the
first polymerization reaction to have a chain extension reaction
with a polyalcohol; (3) controlling the product of the chain
extension reaction and one part of hydroxyalkyl acrylate monomer to
have an additive reaction, and then introducing the other part of
hydroxyalkyl acrylate monomer and a styrene monomer, and
emulsifying in water to obtain an emulsion; (4) mixing a radical
initiator with the emulsion to have a second polymerization
reaction.
Inventors: |
JIANG; Guancheng; (Beijing,
CN) ; GAO; Deli; (Beijing, CN) ; ZHANG;
Shuo; (Beijing, CN) ; WANG; Yong; (Beijing,
CN) ; WU; Xianzhu; (Chengdu City, CN) ; HAN;
Liexiang; (Beijing, CN) ; WANG; Xiangzeng;
(Beijing, CN) ; PENG; Chunyao; (Beijing, CN)
; HE; Yinbo; (Beijing, CN) ; LIU; Fan;
(Beijing, CN) ; ZUO; Hongguo; (Beijing, CN)
; ZHANG; Yongqing; (Beijing, CN) ; YANG; Lili;
(Beijing, CN) ; LI; Zhong; (Beijing, CN) ;
LI; Yanjun; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
China University of Petroleum (Beijing) |
Beijing |
|
CN |
|
|
Assignee: |
China University of Petroleum
(Beijing)
Changping District
CN
|
Family ID: |
61061451 |
Appl. No.: |
16/130694 |
Filed: |
September 13, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/08 20130101;
C08G 18/7671 20130101; C09K 8/12 20130101; C08G 18/10 20130101;
C08G 18/348 20130101; C08G 18/3206 20130101; C08G 18/7678 20130101;
C08G 18/04 20130101; C08F 212/08 20130101; C08G 18/0823 20130101;
C08F 290/067 20130101; C08G 18/7621 20130101; C08G 18/06 20130101;
C08F 290/067 20130101; C08G 18/672 20130101; C08G 18/4277 20130101;
C08G 18/73 20130101; C08G 18/10 20130101; C08G 18/246 20130101;
C08G 18/755 20130101 |
International
Class: |
C09K 8/12 20060101
C09K008/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 20, 2017 |
CN |
201710855400.4 |
Claims
1. A method for preparing a film former used for coal-bed gas well
drilling, comprising: (1) performing a first polymerization
reaction that includes reacting polycaprolactone diol and
diisocyanate in the presence of a polyurethane catalyst to obtain a
polyurethane prepolymer with two ends blocked by diisocyanate; (2)
reacting the product of the first polymerization reaction with a
polyalcohol in a chain extension reaction; (3) performing an
additive reaction on the product of the chain extension reaction
and one part of hydroxyalkyl acrylate monomer; and then introducing
the other part of hydroxyalkyl acrylate monomer and a styrene
monomer, and emulsifying in water to obtain an emulsion; (4) mixing
a radical initiator with the emulsion to have a second
polymerization reaction; wherein the number-average molecular
weight of the polycaprolactone diol is 1,000-6,000; and the weight
ratio of the diisocyanate: the polycaprolactone diol: the
hydroxyalkyl acrylate monomer: the styrene monomer is
100:20-80:50-150:10-50.
2. The method according to claim 1, wherein the weight ratio of the
diisocyanate: the polycaprolactone diol: the hydroxyalkyl acrylate
monomer: the styrene monomer is 100:30-60:80-150:10-50.
3. The method according to claim 1, wherein the weight ratio of the
diisocyanate: the polycaprolactone diol: the hydroxyalkyl acrylate
monomer: the styrene monomer is 100:40-50:100-120:20-40.
4. The method according to claim 1, wherein the diisocyanate is one
or more of diphenylmethane-4,4'-diisocyanate,
diphenylmethane-2,4'-diisocyanate,
diphenylmethane-2,2'-diisocyanate, isophorone diisocyanate,
hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene
diisocyanate, 1,5-naphthalene diisocyanate, and 1,8-naphthalene
diisocyanate; the hydroxyalkyl acrylate monomer is one or more of
hydroxymethyl methacrylate, hydroxyethyl methacrylate,
hydroxypropyl methacrylate, hydroxymethyl acrylate, hydroxyethyl
acrylate, and hydroxypropyl acrylate; and the styrene monomer is
one or more of styrene, p-methyl styrene, m-methyl styrene,
o-methyl styrene, p-ethyl styrene, m-ethyl styrene, o-ethyl
styrene, 2,4-dimethyl styrene, 2,5-dimethyl styrene, and
2,6-dimethyl styrene.
5. The method according to claim 1, wherein the number-average
molecular weight of the polycaprolactone diol is 2,000-5,000.
6. The method according to claim 1, wherein the polyurethane
catalyst is one or more of dibutyltin dilaurate, octylstannylene,
and 2-ethylhexanolstannylene.
7. The method according to claim 6, wherein based on the total
weight of the polycaprolactone diol and the diisocyanate, the dose
of the polyurethane catalyst is 0.05-2 wt %.
8. The method according to claim 7, wherein based on the total
weight of the polycaprolactone diol and the diisocyanate, the dose
of the polyurethane catalyst is 0.05-1 wt %.
9. The method according to claim 1, wherein the polyalcohol is one
or more of dihydromethyl propionic acid, 1,4-butanediol, glycerol,
sorbitol, ethylene glycol, pentaerythritol, and mannitol.
10. The method according to claim 9, wherein the weight ratio of
the diisocyanate to the polyalcohol is 100:5-20.
11. The method according to claim 1, wherein in the step (3), based
on the total weight of the diisocyanate, the polycaprolactone diol,
the hydroxyalkyl acrylate monomer, and the styrene monomer, the
dose of water is 20-50 wt %.
12. The method according to claim 1, wherein the radical initiator
is one or more of potassium persulfate, ammonium persulfate,
dibenzoyl peroxide, diisopropyl peroxydicarbonate, dicyclohexyl
peroxydicarbonate, isopropyl benzene hydroperoxide, teri-butyl
hydroperoxide, azodiisobutyronitrile, and
azobisisoheptonitrile.
13. The method according to claim 12, wherein based on the total
weight of the hydroxyalkyl acrylate monomer and the styrene
monomer, the content of the radical initiator is 0.5-1.5 wt %.
14. The method according to claim 1, wherein in the step (1), the
conditions of the first polymerization reaction include:
temperature: 60-90.degree. C., time: 2-5 h.
15. The method according to claim 1, wherein in the step (2), the
conditions of the chain extension reaction include: temperature:
50-80.degree. C., time: 1-4 h.
16. The method according to claim 1, wherein in the step (3), the
conditions of the additive reaction include: temperature:
50-70.degree. C., time: 0.5-3 h; the conditions of the
emulsification include: temperature: 30-60.degree. C., time: 1-3
h.
17. The method according to claim 1, wherein in the step (4), the
conditions of the second polymerization reaction include:
temperature: 60-90.degree. C., time: 2-5 h.
18. A film former prepared by the method according to claim 1.
19. A water-based drilling fluid that contains the film former
according to claim
18.
20. A method comprising: employing the water-based drilling fluid
according to claim 19 while drilling a coal-bed gas well.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Chinese application no.
201710855400.4, filed on Sep. 20, 2017, entitled "film former used
for coal-bed gas well drilling and preparation method thereof,
drilling fluid and usage thereof", which is specifically and
entirely incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the well drilling field in
the petroleum industry, particularly to a film former used for
coal-bed gas well drilling, a preparation method thereof, a
drilling fluid and a usage thereof.
BACKGROUND OF THE INVENTION
[0003] Coal-bed gas reservoir is quite different from ordinary
sandstone or carbonate reservoir, and has characteristics such as
high adsorbability, low permeability, and susceptibility to
compression and fracture, etc. Owing to those characteristics, the
coal bed is subjected to much more severe injuries than an ordinary
reservoir in the coal-bed gas well drilling process, and the
injuries of the coal-bed gas reservoir have direct influence on the
desorption, diffusion, migration, and subsequent drainage and
mining. Therefore, close attention should be paid to the coal-bed
gas reservoir injury problem. A coal bed is mainly subject to the
following injury factors owing to its characteristics: [0004] (1)
The development of coal bed pores and fissures provides an
objective condition for the solid phase and liquid phase in
external fluids to invade into the coal bed; [0005] (2) The
pore-fissures system and the nature of macromolecular organic
substance of coal create a condition for adsorption of water and
high molecular polymers in external fluids, which has influence on
the permeability of the coal bed; [0006] (3) The water in the coal
bed may have chemical reactions with external fluids easily, and
the resultant compound precipitates may block the fissures in the
coal bed; [0007] (4) Since most coal reservoirs are in an
under-compacted state, leakage may occur easily during drilling and
cause serious injuries to the coal-bed gas reservoir; [0008] (5)
The coal bed is highly sensitive to stress, and the stress damage
resulted from many factors in the drilling process causes decreased
reservoir permeability; [0009] (6) The coal rocks have low
mechanical strength, and the coal powder generated in the well
drilling process may block the pores and fractures in the coal bed
and thereby result in damages to the solid phase in the coal
bed.
[0010] The Patent Document No. CN104910877A has disclosed a film
former composition for drilling fluids, which contains at least one
modified phenol-formaldehyde resin, at least one hydrophobic
monomer, at least one acrylate, and at least one epoxy resin. The
film former obtained in the patent application can achieve
relatively low coal bed leakage at higher temperatures; however,
the patent application hasn't mentioned any coal-bed gas reservoir
protection feature of the film former.
[0011] Drilling fluids are reputed as the blood for well drilling.
Good drilling fluid techniques are one of the important guarantees
for safe, high-quality, efficient, and quick well drilling
production. Drilling/completion fluids are required in the
exploitation of coal-bed gasses. Effective reservoir protection is
an important guarantee for a high rate of oil and gas recovery, so
as to attain an optimal negative skin coefficient. If the
drilling/completion fluid is designed or used inappropriately in
the well drilling/completion process, the liquid and solid in the
drilling fluid may intrude into the oil reservoir and have physical
and chemical reactions with clay and other minerals in the oil and
gas layer. Consequently, the permeability in the oil layer in the
immediate vicinity of the well may be decreased severely, and the
resistance against oil and gas flow towards the bottom of the well
may be increased, resulting in reduced oil yield. The injuries to
the reservoir have critical impacts on effective exploitation of
the reservoir. The major forms of reservoir damages happened in the
coal-bed gas well drilling process include: [0012] (1) The drilling
fluid is absorbed by the coal rocks, resulting in decreased
permeability of the coal rocks; [0013] (2) The solid particles in
the drilling fluid fill and plug the channels formed by fissures;
[0014] (3) A polymer drilling fluid invades into the coal bed and
causes clay flocculation and blockage under the adsorptive action
of high molecular polymers, as well as clay swelling and blockage
under the action of carboxyl hydration, and thereby results in
decreased permeability of the coal bed; [0015] (4) The drilling
fluid interacts with the formation water and generate solid
precipitates, which result in blockage of channels formed by
pores.
[0016] Production factors in the well drilling process, such as
excessively high pressure of the drilling fluid column, reservoir
bed soaked in the drilling fluid for an excessively long time, and
excessively high pressure, etc., may also cause injuries to the
coal bed. Furthermore, well cementing operation and reservoir
reformation measures taken to improve the yield (e.g., hydraulic
fracturing) may also cause injuries to the coal-bed gas reservoir
in different degree.
SUMMARY OF THE INVENTION
[0017] In view the problem that the coal-bed gas reservoirs are
subject to injuries and damages in the prior art, the present
invention provides a film former that is used for coal-bed gas well
drilling and helpful for coal-bed gas reservoir protection, a
preparation method of the film former, and a drilling fluid and an
usage of the drilling fluid.
[0018] To attain the objects described above, in a first aspect,
the present invention provides a method for preparing a film former
used for coal-bed gas well drilling, which comprises: [0019] (1)
controlling polycaprolactone diol and diisocyanate to have a first
polymerization reaction in the presence of a polyurethane catalyst,
to obtain a polyurethane prepolymer with two ends blocked by
diisocyanate; [0020] (2) controlling the product of the first
polymerization reaction to have a chain extension reaction with a
polyalcohol; [0021] (3) controlling the product of the chain
extension reaction and one part of hydroxyalkyl acrylate monomer to
have an additive reaction, and then introducing the other part of
hydroxyalkyl acrylate monomer and a styrene monomer, and
emulsifying in water to obtain an emulsion; [0022] (4) mixing a
radical initiator with the emulsion to have a second polymerization
reaction;
[0023] wherein, the number-average molecular weight of the
polycaprolactone diol is 1,000-6,000;
[0024] the weight ratio of the diisocyanate: the polycaprolactone
diol: the hydroxyalkyl acrylate monomer: the styrene monomer is
100:20-80:50-150:10-50.
[0025] In a second aspect, the present invention provides a film
former prepared by the method described above.
[0026] In a third aspect, the present invention provides a
water-based drilling fluid that contains the above-mentioned film
former.
[0027] In a fourth aspect, the present invention provides an usage
of the above-mentioned water-based drilling fluid in coal-bed gas
well drilling.
[0028] The film former provided in the present invention enables a
drilling fluid system to have good film-forming performance on rock
surfaces, and is helpful for protection of coal-bed gas
reservoir.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] 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.
[0030] In a first aspect, the present invention provides a method
for preparing a film former used for coal-bed gas well drilling,
which comprises: [0031] (1) controlling polycaprolactone diol and
diisocyanate to have a first polymerization reaction in the
presence of a polyurethane catalyst, to obtain a polyurethane
prepolymer with two ends blocked by diisocyanate; [0032] (2)
controlling the product of the first polymerization reaction to
have a chain extension reaction with a polyalcohol; [0033] (3)
controlling the product of the chain extension reaction and one
part of hydroxyalkyl acrylate monomer to have an additive reaction,
and then introducing the other part of hydroxyalkyl acrylate
monomer and a styrene monomer, and emulsifying in water to obtain
an emulsion; [0034] (4) mixing a radical initiator with the
emulsion to have a second polymerization reaction;
[0035] wherein, the number-average molecular weight of the
polycaprolactone diol is 1,000-6,000;
[0036] the weight ratio of the diisocyanate: the polycaprolactone
diol: the hydroxyalkyl acrylate monomer: the styrene monomer is
100:20-80:50-150:10-50.
[0037] According to the present invention, preferably, the weight
ratio of the diisocyanate: the polycaprolactone diol: the
hydroxyalkyl acrylate monomer: the styrene monomer is
100:30-60:80-150:10-50, preferably is 100:40-50:100-120:20-40, more
preferably is 100:40-50:100-120:30-40.
[0038] According to the present invention, within the
above-mentioned dose range, in the step (1), the polyurethane
prepolymer with two ends blocked by diisocyanate is obtained
through an addition condensation reaction between polycaprolactone
diol and diisocyanate.
[0039] Wherein, the number-average molecular weight of the
polycaprolactone diol preferably is 2,000-5,000, e.g., 3,000-4,000.
The polycaprolactone diol may be dehydrated before it is used; for
example, it may be vacuum-dehydrated at 100-140.degree. C. for 1-3
h.
[0040] According to the present invention, the polyurethane
catalyst may be a metal organic compound polyurethane catalyst,
preferably is one or more of dibutyltin dilaurate, octylstannylene,
and 2-ethylhexanolstannylene, more preferably is dibutyltin
dilaurate and/or octylstannylene.
[0041] According to the present invention, the dose of the
polyurethane catalyst may vary within a wide range. To produce a
polymer that is more suitable for a film former for drilling
fluids, preferably, based on the total weight of the
polycaprolactone diol and the diisocyanate, the dose of the
polyurethane catalyst is 0.05-2 wt %, preferably is 0.05-1 wt
%.
[0042] According to the present invention, the diisocyanate
preferably is one or more of diphenylmethane-4,4'-diisocyanate
(4,4'-MDI), diphenylmethane-2,4'-diisocyanate (2,4'-MDI),
diphenylmethane-2,2'-diisocyanate (2,2'-MDI), isophorone
diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 2,4-toluene
diisocyanate (2,4-TDI), 2-6-toluene diisocyanate (2,6-TDI),
1,5-naphthalene diisocyanate (1,5-NDI), and 1,8-naphthalene
diisocyanate (1,8-NDI), more preferably is isophorone diisocyanate
(IPDI).
[0043] Preferably, in the step (1), the conditions of the first
polymerization reaction include: temperature: 60-90.degree. C.,
time: 2-5 h. More preferably, in the step (1), the conditions of
the first polymerization reaction include: temperature:
70-90.degree. C., time: 3-4 h.
[0044] According to the present invention, in the step (2), the
mixture including all product obtained in the step (1) is mixed
with a polyalcohol to have a reaction, so that the polyalcohol, the
remaining diisocyanate, and the polyurethane prepolymer with two
ends blocked by diisocyanate have an addition polymerization
reaction under the action of the polyurethane catalyst in the step
(1), to obtain polyurethane with extended chain segments.
[0045] Wherein, the polyalcohol preferably is one or more of
dihydromethyl propionic acid, 1,4-butanediol, glycerol, sorbitol,
ethylene glycol, pentaerythritol, and mannitol, more preferably is
a combination of dihydromethyl propionic acid and 1,4-butanediol,
particularly preferably is a combination of dihydromethyl propionic
acid and 1,4-butanediol at 1:0.5-1 weight ratio.
[0046] According to the present invention, the dose of the
polyalcohol may vary within a wide range. To obtain polyurethane
with moderately extended chain segments through the chain extension
reaction, preferably, the weight ratio of the diisocyanate to the
polyalcohol is 100:5-20, preferably is 100:10-15.
[0047] Preferably, in the step (2), the conditions of the chain
extension reaction include: temperature: 50-80.degree. C., time:
1-4 h. More preferably, the conditions of the chain extension
reaction include: temperature: 50-80.degree. C., time: 1-4 h.
[0048] According to the present invention, in the step (3), one
part of hydroxyalkyl acrylate monomer and the product obtained
through the chain extension reaction in the step (3) are controlled
to have an additive reaction first, so that the hydroxyl groups in
the hydroxyalkyl acrylate monomer have an additive reaction with
the terminal diisocyanate in the product of the chain extension
reaction, and thereby the polyurethane obtained through the chain
extension reaction bears carbon-carbon double bonds provided by
hydroxyalkyl acrylate; thus, in the following free radical
polymerization, the carbon-carbon double bonds provided by
hydroxyalkyl acrylate on the polyurethane have a polymerization
reaction with free hydroxyalkyl acrylate monomer and styrene
monomer or a polymer of hydroxyalkyl acrylate monomer and styrene
monomer to form a three-dimensional network structure, and thereby
a film former according to the present invention is obtained.
[0049] Wherein, preferably, the hydroxyalkyl acrylate monomer is
one or more of hydroxymethyl methacrylate, hydroxyethyl
methacrylate, hydroxypropyl methacrylate, hydroxymethyl acrylate,
hydroxyethyl acrylate, and hydroxypropyl acrylate. Preferably, the
weight ratio of said one part of hydroxyalkyl acrylate monomer to
the other part of hydroxyalkyl acrylate monomer is 1:1-5.
[0050] According to the present invention, the styrene monomer
preferably is one or more of styrene, p-methyl styrene, in-methyl
styrene, o-methyl styrene, p-ethyl styrene, in-ethyl styrene,
o-ethyl styrene, 2,4-dimethyl styrene, 2,5-dimethyl styrene, and
2,6-dimethyl styrene.
[0051] According to the present invention, in the step (3), the
dose of water may vary in a wide range, as long as an emulsion
suitable for the second polymerization reaction can be obtained.
Preferably, in the step (3), based on the total weight of the
diisocyanate, the polycaprolactone diol, the hydroxyalkyl acrylate
monomer, and the styrene monomer, the dose of the water is 20-50 wt
%, e.g., 25-35 wt %.
[0052] According to the present invention, to improve the
dispersity among the organic substances, an organic solvent may be
introduced before the emulsification in the step (3). The organic
solvent may be one or more of triethylamine, ethylene diamine,
ethanol amine, and di-ethanolamine, etc., for example, and the dose
of the organic solvent may vary within a wide range; preferably, in
the step (3), based on the total weight of the diisocyanate, the
polycaprolactone diol, the hydroxyalkyl acrylate monomer, and the
styrene monomer, the dose of the organic solvent is 2-10 wt %,
preferably is 5-8 wt %.
[0053] According to the present invention, preferably, in the step
(3), the conditions of the additive reaction include: temperature:
50-70.degree. C., time: 0.5-3 h; the conditions of the
emulsification include: temperature: 30-60.degree. C. (preferably
40-50.degree. C.), time: 1-3 h.
[0054] According to the present invention, in the step (4), the
radical initiator preferably is one or more of potassium
persulfate, ammonium persulfate, dibenzoyl peroxide, diisopropyl
peroxydicarbonate, dicyclohexyl peroxydicarbonate, isopropyl
benzene hydroperoxide, teri-butyl hydroperoxide,
azodiisobutyronitrile, and azobisisoheptonitrile, more preferably
is one or more of potassium persulfate, ammonium persulfate,
dibenzoyl peroxide, diisopropyl peroxydicarbonate, and dicyclohexyl
peroxydicarbonate.
[0055] Wherein, the dose of the radical initiator may vary within a
wide range, as long as the film former according to the present
invention can be obtained; preferably, based on the total weight of
the hydroxyalkyl acrylate monomer and the styrene monomer, the
content of the radical initiator is 0.5-1.5 wt %.
[0056] According to the present invention, preferably, in the step
(4), the conditions of the second polymerization reaction include:
temperature: 60-90.degree. C., time: 2-5 h. More preferably, the
conditions of the second polymerization reaction include:
temperature: 70-85.degree. C., time: 3-4 h.
[0057] Through the process described above, a milk white viscous
fluid, i.e., the film former according to the present invention, is
obtained finally. The solid content of such a film former is 60-80
wt %.
[0058] In a second aspect, the present invention provides a film
former prepared by the method described above.
[0059] In a third aspect, the present invention provides a
water-based drilling fluid that contains the above-mentioned film
former.
[0060] According to the present invention, the dose of the film
former may be selected according to the specific rock formation
condition; preferably, with respect to 100 pbw (parts by weight)
water in the water-based drilling fluid, the dose of the film
former is 1-3 pbw.
[0061] Usually, the water-based drilling fluid may further contain
other additives for water-based drilling fluid; preferably, the
drilling fluid in the present invention contains one or more of
bentonite, pH adjuster, filtrate reducer, weighting agent,
inhibitor, wettability reversal agent, and protectant, etc.
[0062] Wherein, the bentonite is a kind of clay with
montmorillonite as the main mineral component, which can render
viscous shearing strength, leak-off and wall building capabilities
to the drilling fluid; for example, the bentonite may be sodium
bentonite and/or calcium bentonite, preferably is sodium bentonite.
More preferably, with respect to 100 pbw water in the water-based
drilling fluid, the content of the bentonite is 2-5 pbw, more
preferably is 2-3 pbw.
[0063] Wherein, the pH adjuster ensures that the drilling fluid
system is an alkaline environment. For example, the pH adjuster may
be selected from one or more of sodium hydroxide, potassium
hydroxide, potassium carbonate, and sodium carbonate. More
preferably, with respect to 100 pbw water in the water-based
drilling fluid, the content of the pH adjuster is 0.3-1 pbw.
[0064] Wherein, the filtrate reducer can improve the leak-off and
wall building capabilities of the drilling fluid. For example, the
filtrate reducer may be selected from one or more of polymeric
filtrate reducer (trade name: Redul), PAC-LV, ammonium salt,
sulfomethylated phenolic resin (e.g., trade name: SMP-I, SMP-II),
sulfomethylated lignite resin (e.g., trade name: SPNH), and
zwitterionic polymer JT-888, preferably is one or more of Redul,
SMP-II and SPNH. More preferably, with respect to 100 pbw water in
the water-based drilling fluid, the content of the filtrate reducer
is 2-5 pbw.
[0065] Wherein, the purpose of the weighting agent is to adjust the
density of the drilling fluid to a required density. For example,
the weighting agent may be one or more of barite (e.g., barite with
90 wt % or higher barium sulfate content), organic salts (Weigh-1,
Weigh-2 (the active ingredient is potassium formate), Weigh-3, and
organic sodium salt GD-WT), and inorganic salts (e.g., NaCl, KCl,
and BaSO.sub.4), etc. Preferably, with respect to 100 pbw water in
the water-based drilling fluid, the content of the weighting agent
is 2-5 pbw.
[0066] Wherein, the inhibitor can inhibit hydrated swelling of the
rock formation. For example, the inhibitor may be polyethylene
glycol (with number-average molecular weight within a range of
2,000-20,000). More preferably, with respect to 100 pbw water in
the water-based drilling fluid, the content of the inhibitor is 2-5
pbw.
[0067] Wherein, the wettability reversal agent can be absorbed to
the rock surface very easily and decreases the surface energy of
the rock surface, so that the rock is bestowed with a hydrophobic
and oleophobic property, water and oil intrusion can be avoided
effectively, and the occurrence of a capillary phenomenon can be
prevented, and thereby a well wall stabilization and reservoir
protection effect is attained. For example, the hydrophobic and
oleophobic wettability reversal agent disclosed in the Patent
Document No. CN 106634894 A may be used. More preferably, with
respect to 100 pbw water in the water-based drilling fluid, the
content of the wettability reversal agent is 0.5-0.8 pbw.
[0068] Wherein, the protectant can protect the reservoir from
water-sensitivity damage brought by the drilling fluid and inhibit
hydrated swelling and dispersion of mud shale. For example, such a
protectant may be the reservoir protectant disclosed in the Patent
Document No. CN 104610485 A. More preferably, with respect to 100
pbw water in the water-based drilling fluid, the content of the
protectant is 1-4 pbw.
[0069] Each of 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.
[0070] In a fourth aspect, the present invention provides a usage
of the above-mentioned water-based drilling fluid in coal-bed gas
well drilling.
[0071] The film former provided in the present invention enables a
drilling fluid system to have good film-forming performance on rock
surfaces, and is helpful for protection of coal-bed gas
reservoir.
[0072] Hereunder the present invention will be detailed in
embodiments.
EXAMPLE 1
[0073] This example is provided to describe the film former and the
preparation method of the film former provided in the present
invention. [0074] (1) 40 pbw polycaprolactone diol (with
number-average molecular weight equal to 2,000, from DAICEL Group)
is heated up to 120.degree. C. and vacuum-dehydrated at this
temperature for 2 h; then the polycaprolactone diol is cooled to
80.degree. C., 100 pbw isophorone diisocyanate is added, and then
dibutyltin dilaurate is added by dropwise adding (based on the
total weight of the polycaprolactone diol and the diisocyanate, the
dose of the dibutyltin dilaurate is 0.08 wt %), and the obtained
mixture is held at 80.degree. C. for 3 h for reaction; [0075] (2)
The product obtained in the step (1) is cooled to 70.degree. C., 5
pbw dried and dehydrated dihydromethyl propionic acid and 10 pbw
dried and dehydrated 1,4-butanediol are added, and the obtained
mixture is held at 70.degree. C. for 2 h for chain extension
reaction; [0076] (3) The product obtained through the chain
extension reaction is cooled to 60.degree. C., 50 pbw hydroxyethyl
methacrylate is added, and the obtained mixture is held at
60.degree. C. for 1.5 h for reaction; then, the resultant product
is cooled to 40.degree. C., 70 pbw hydroxyethyl methacrylate, 30
pbw styrene, and 20 pbw ethylene diamine are added, and the
obtained mixture is stirred for 0.5 h, then 100 pbw water is added
to emulsify and disperse at a high speed to obtain an emulsion;
[0077] (4) Potassium persulfate (based on the total weight of the
hydroxyalkyl acrylate monomer and the styrene monomer, the dose of
the potassium persulfate is 1 wt %) is added into the emulsion, and
the mixture is held at 80.degree. C. for 3.5 h for free radical
polymerization; thus, a milk white viscous liquid, i.e., a film
former CM-1, is obtained, and the solid content of the liquid
(percentage of the weight in dryness to the total weight of the
liquid) is 70 wt %.
EXAMPLE 2
[0078] This example is provided to describe the film former and the
preparation method of the film former provided in the present
invention. [0079] (1) 50 pbw polycaprolactone diol (with
number-average molecular weight equal to 3,000, from DAICEL Group)
is heated up to 120.degree. C. and vacuum-dehydrated at this
temperature for 2 h; then the polycaprolactone diol is cooled to
90.degree. C., 100 pbw diphenylmethane-4,4'-diisocyanate is added,
and then dibutyltin dilaurate is added by dropwise adding (based on
the total weight of the polycaprolactone diol and the diisocyanate,
the dose of the dibutyltin dilaurate is 0.05 wt %), and the
obtained mixture is held at 90.degree. C. for 2.5 h for reaction;
[0080] (2) The product obtained in the step (1) is cooled to
80.degree. C., 8 pbw dried and dehydrated pentaerythritol and 2 pbw
dried and dehydrated ethylene glycol are added, and the obtained
mixture is held at 80.degree. C. for 3 h for chain extension
reaction; [0081] (3) The product obtained through the chain
extension reaction is cooled to 65.degree. C., 40 pbw hydroxypropyl
methacrylate is added, and the obtained mixture is held at
65.degree. C. for 2 h for reaction; then, the resultant product is
cooled to 50.degree. C., 60 pbw hydroxypropyl methacrylate, 40 pbw
p-methyl styrene, and 15 pbw triethylamine are added, and the
obtained mixture is stirred for 0.5 h, then 120 pbw water is added
to emulsify and disperse at a high speed to obtain an emulsion;
[0082] (4) Ammonium persulfate (based on the total weight of the
hydroxyalkyl acrylate monomer and the styrene monomer, the dose of
the ammonium persulfate is 1.2 wt %) is added into the emulsion,
and the mixture is held at 75.degree. C. for 4 h for free radical
polymerization; thus, a milk white viscous liquid, i.e., a film
former CM-2, is obtained, and the solid content of the liquid
(percentage of the weight in dryness to the total weight of the
liquid) is 65 wt %.
EXAMPLE 3
[0083] This example is provided to describe the film former and the
preparation method of the film former provided in the present
invention.
[0084] The method described in the example 1 is used, but the
polycaprolactone diol is polycaprolactone diol with number-average
molecular weight equal to 1,000 from DAICEL group. A film former
CM-3 is obtained finally, and the solid content of the film former
is 70 wt %.
EXAMPLE 4
[0085] This example is provided to describe the film former and the
preparation method of the film former provided in the present
invention.
[0086] The method described in the embodiment 1 is used, but:
[0087] The dose of the polycaprolactone diol is 20 pbw;
[0088] The total dose of the hydroxyethyl methacrylate is 150 pbw,
wherein, 80 pbw hydroxyethyl methacrylate is introduced first to
have a reaction with the product of the chain extension reaction,
and then the remaining hydroxyethyl methacrylate is introduced;
[0089] A film former CM-4 is obtained finally, and the solid
content of the film former is 72 wt %.
EXAMPLE 5
[0090] This example is provided to describe the film former and the
preparation method of the film former provided in the present
invention.
[0091] The method described in the embodiment 1 is used, but:
[0092] The dose of the polycaprolactone diol is 80 pbw;
[0093] The total dose of the hydroxyethyl methacrylate is 60 pbw,
wherein, 30 pbw hydroxyethyl methacrylate is introduced first to
have a reaction with the product of the chain extension reaction,
and then the remaining hydroxyethyl methacrylate is introduced;
[0094] A film former CM-5 is obtained finally, and the solid
content of the film former is 70 wt %.
Comparative Example 1
[0095] This comparative example is provided to describe the film
former and the preparation method of the film former according to
reference method.
[0096] The method described in the example 1 is used, but the
polycaprolactone diol is polycaprolactone diol with number-average
molecular weight equal to 500 from DAICEL group. A film former
DCM-1 is obtained finally, and the solid content of the film former
is 70 wt %.
Comparative Example 2
[0097] This comparative example is provided to describe the film
former and the preparation method of the film former according to
reference method.
[0098] The method described in the example 1 is used, but:
[0099] The dose of the polycaprolactone diol is 120 pbw;
[0100] The total dose of the hydroxyethyl methacrylate is 40 pbw,
wherein, 20 pbw hydroxyethyl methacrylate is introduced first to
have a reaction with the product of the chain extension reaction,
and then the remaining hydroxyethyl methacrylate is introduced;
[0101] A film former DCM-2 is obtained finally, and the solid
content of the film former is 70 wt %.
Comparative Example 3
[0102] This comparative example is provided to describe the film
former and the preparation method of the film former according to
reference method.
[0103] The method described in the example 1 is used, but:
[0104] The dose of the polycaprolactone diol is 10 pbw;
[0105] The total dose of the hydroxyethyl methacrylate is 180 pbw,
wherein, 100 pbw hydroxyethyl methacrylate is introduced first to
have a reaction with the product of the chain extension reaction,
and then the remaining hydroxyethyl methacrylate is introduced;
[0106] The dose of the styrene is 10 pbw;
[0107] A film former DCM-3 is obtained finally, and the solid
content of the film former is 72 wt %.
Comparative Example 4
[0108] This comparative example is provided to describe the film
former and the preparation method of the film former according to
reference method.
[0109] The method described in the example 1 is used, but the
styrene is replaced with 30 pbw hydroxyethyl methacrylate, i.e., in
the step (3), the dose of the latter part of hydroxyethyl
methacrylate is 100 pbw;
[0110] A film former DCM-4 is obtained finally, and the solid
content of the film former is 70 wt %.
Preparation Example 1 of the Protectant
[0111] Styrene (15 g, 0.14 mol), N,N-dimethylamino ethyl
methacrylate (11.3 g, 0.072 mol), 2-acrylamido-2-methyl
propanesulfonic acid (14.9 g, 0.072 mol), and N,N-diethylacrylamide
(3.66 g, 0.029 mol) are added into 100 mL water, and the mixture is
stirred to form an emulsion; nitrogen is charged into the emulsion
for 30 min., then the emulsion is heated up to 70.degree. C. and at
the same time 0.5 g 4,4'-azobis(4-cyanovaleric acid) is added;
next, the emulsion is further heated up to 75.degree. C. and held
at this temperature for 6 h for reaction; after the reaction is
completed, the reaction solution is cooled to room temperature
(20.degree. C.), and the aqueous dispersion of the product is
evaporated in a rotary evaporator to dry state, and the obtained
solid is pulverized; thus, an amphiphilic reservoir protectant QJ-1
according to the present invention is obtained. The weight-average
molecular weight is 213,200 g/mol, and the molecular weight
distribution index is 2.3.
Preparation Example 1 of Wettability Reversal Agent
[0112] (1) 0.12mol N,N-dimethyl-1,3-propylene diamine is dissolved
in 250 mL methylene chloride at 0-5.degree. C., then 0.12 mol
triethylamine is added, and the obtained mixture is stirred for 30
min.; next, 0.1 mol perfluoro butanesulfonylfluoride is added by
dropwise adding at 0-5.degree. C. (the addition is completed within
about 30 min., trade name 375-72-4 from Hubei Jusheng Technology
Co., Ltd.), the mixture is held at 0-5.degree. C. for 60 min. for
further reaction, and then is cooled to 25.degree. C. and held at
this temperature for 4 h for reaction; the obtained product is
filtered, the filter cake is washed with methylene chloride, dried,
and then recrystallized with acetone; thus, a 128.7 g white solid
is obtained; [0113] (2) 10 mmol compound obtained in the step (1)
is dissolved in 50 mL ethanol at 65.degree. C., then 11 mmol
1,4-dibromobutane is added by dropwise adding (the addition is
completed within about 20 min.), and the mixture is stirred at
75.degree. C. for 6 h for reaction; the product of the reaction is
cooled to room temperature (about 25.degree. C.) and crystallizes,
and then is filtered, and the filter cake is washed and dried;
thus, 12.34 g solid, i.e., a wettability reversal agent S S-1, is
obtained.
Drilling Fluid Example 1
[0114] This example is provided to describe the water-based
drilling fluid in the present invention.
[0115] Formulation: 100 pbw water, 2 pbw film former CM-1, 1 pbw
protectant QJ-1, 1 pbw wettability reversal agent SS-1, 3 pbw
polyethylene glycol (PEG600 from Jiangsu Haian Petrochemical
Plant), 4 pbw NaCl, 0.3 pbw Na.sub.2CO.sub.3, 0.5 pbw NaOH, 3 pbw
sodium bentonite (from Shandong Weifang Huawei Bentonite Co., Ltd.,
the same below), and 3 pbw SMP-II (from Jiangxi Pingxiang Hengchang
New Chemical Materials Co., Ltd., the same below); thus, a
water-based drilling fluid Y1 is obtained.
Drilling Fluid Examples 2-5
[0116] These examples is provided to describe the water-based
drilling fluid in the present invention.
[0117] The formulation described in the drilling fluid example 1 is
used, but the film former CM-1 is replaced with film formers CM-2
to CM-5 respectively. Thus, water-based drilling fluids Y2-Y5 are
obtained respectively.
Drilling Fluid Comparative Examples 1-4
[0118] These comparative examples is provided to describe the
water-based drilling fluid for reference.
[0119] The formulation described in the drilling fluid embodiment 1
is used, but the film former CM-1 is replaced with the film formers
DCM-1 to DCM-4 respectively. Thus, water-based drilling fluids
DY1-DY4 are obtained respectively.
Drilling Fluid Comparative Example 5
[0120] This comparative example is provided to describe the
water-based drilling fluid for reference.
[0121] The formulation described in the drilling fluid example 1 is
used, but the film former CM-1 is omitted. Thus, a water-based
drilling fluid DY5 is obtained.
Test Example 1
[0122] The rheological property and filtration property of the
above-mentioned drilling fluids are measured respectively.
Specifically, the apparent viscosity (AV), plastic viscosity (PV),
yield point (YP), ratio of initial gel strength/final gel strength
(G10''/10'), medium pressure filter loss (API), and high pressure
filter loss (HTHP) of the obtained drilling fluids are measured
before aging and after aging at 120.degree. C. for 16 h and cooling
to room temperature respectively. The results are shown in Table 1,
wherein:
[0123] 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
.
[0124] 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.
[0125] 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.
[0126] The ratio of initial gel strength/final gel strength
(G10''/10') is measured with a FANN six-speed viscosity meter with
the method specified in the national standard GB/T29170-2012, in
unit of Pa/Pa.
[0127] API refers to medium pressure filter loss, and is measured
with an medium pressure filter loss meter with the method specified
in the standard SY/T5621-93, in unit of mL
[0128] HTHP (150.degree. C., 3.5 MPa) 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-00001 TABLE 1 Drilling AV PV YP G10''/10' API HTHP Fluid
(mPa s) (mPa s) (Pa) (Pa/Pa) (mL) (mL) Before aging DY5 85 45 49
8.0/9.5 13.6 / Y1 89 46 46 8.5/9.5 5.8 / Y2 86 45 43 8.0/9.0 5.9 /
Y3 88 46 45 8.5/9.0 6.8 / Y4 87 48 45 8.5/9.0 6.3 / Y5 85 47 47
8.0/9.5 6.5 / DY1 79 42 42 7.5/8.5 9.8 / DY2 81 43 41 7.5/8.0 9.2 /
DY3 82 42 43 8.0/8.5 9.1 / DY4 77 41 40 7.5/8.0 9.6 / After aging
at 120.degree. C. for 16 h DY5 86 47 46 7.0/8.5 18.3 31.8 Y1 87 45
44 6.5/9.0 9.2 12.5 Y2 86 44 45 6.0/8.5 9.1 12.9 Y3 85 46 44
6.0/8.0 10.7 15.8 Y4 85 47 43 6.0/8.5 9.9 14.5 Y5 84 46 46 6.5/8.5
10.3 15.3 DY1 83 43 41 5.5/8.0 15.4 28.5 DY2 82 43 42 5.5/8.5 16.3
25.1 DY3 82 42 41 6.0/8.0 15.2 24.6 DY4 81 41 40 5.5/8.0 16.8
23.8
Test Example 2
[0129] (1) The roll recovery ratio testing process is as follows:
Each of the above-mentioned drilling fluids measured in 350 mL
volume and clear water are loaded into a high-speed mixing cup and
stirred at a high speed for 5 min., then the mixture is poured into
an aging tank for later use; 6-10mesh drill cuttings are baked at
105.degree. C. to constant weight and then cooled to room
temperature. 50 g dried drill cuttings (G.sub.0) is weighed and
added into a drilling fluid to be tested, aged at 120.degree. C.
for 16 h, cooled, and taken out from the aging tank; the well core
is recovered using a 40-mesh filter screen (and washed with tap
water), baked at 105.+-.3.degree. C. to constant weight, and cooled
to room temperature and weighed the recovered well core mass
(G.sub.1);
[0130] Mud shale recovery ratio R=G.sub.1/G.sub.0.times.100%
[0131] Wherein, G.sub.0 is the mass of raw shale, in unit of g;
G.sub.1 is the mass of recovered shale; R is the recovery ratio of
shale, %. [0132] (2) The shale swelling ratio testing process is as
follows: Each of the above-mentioned drilling fluid measured in 20
mL volume and clear water are loaded into a beaker for later use; 5
g rock cuttings dried at 105.degree. C. is weighed and loaded into
a test cylinder, a plug stick is inserted into the test cylinder,
and the test cylinder is held at 4 MPa pressure for 5 min.; thus, a
test well core is obtained, and the initial height h.sub.0 of the
rock sample is measured. The test cylinder with the well core is
mounted on a shale swelling tester, a fluid to be tested is
injected into the test cylinder, and soaking for a different time,
and the swelling amount h.sub.t of the well core is recorded at
different time points.
[0133] Linear swelling ratio of mud shale:
E=(h.sub.t-h.sub.0)/h.sub.0.times.100%.
[0134] The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Mud shale Linear swelling ratio Drilling
recovery ratio of mud shale % Fluid % 2 h 4 h 8 h Clear water 15.6
70.1 71.8 73.5 Y1 93.1 8.2 10.5 12.1 Y2 92.5 8.1 10.3 12.0 Y3 86.6
8.3 11.6 15.3 Y4 91.2 8.4 10.7 14.4 Y5 89.3 8.5 10.8 14.5 DY1 83.5
9.2 12.3 17.2 DY2 84.7 9.9 12.7 17.9 DY3 83.8 10.5 13.1 18.3 DY4
81.9 11.3 14.6 19.5
[0135] It can be seen from the data in the above Tables 1-2: a
water-based drilling fluid that contains the film former according
to the present invention attains a good protective effect for shale
storage.
[0136] While the present invention is described above in detail in
some preferred embodiments, the present invention is not limited to
those embodiments.
[0137] Various simple variations, including combinations of the
technical features in any other appropriate way, can be made to the
technical scheme of the present invention within the scope of the
technical concept of the present invention, but such variations and
combinations shall be deemed as disclosed content in the present
invention and falling in the protection scope of the present
invention.
* * * * *