U.S. patent application number 16/040307 was filed with the patent office on 2019-04-25 for modified nano-graphite particle three-phase foam profile control and flooding system and preparation method thereof.
This patent application is currently assigned to CHINA UNIVERSITY OF PETROLEUM (EAST CHINA). The applicant listed for this patent is CHINA UNIVERSITY OF PETROLEUM (EAST CHINA). Invention is credited to Caili DAI, Chenglin GU, Yuyang LI, Yahui LV, Yongpeng SUN, Yining WU, Qing YOU, Guang ZHAO, Mingwei ZHAO.
Application Number | 20190119560 16/040307 |
Document ID | / |
Family ID | 61662410 |
Filed Date | 2019-04-25 |
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United States Patent
Application |
20190119560 |
Kind Code |
A1 |
ZHAO; Guang ; et
al. |
April 25, 2019 |
MODIFIED NANO-GRAPHITE PARTICLE THREE-PHASE FOAM PROFILE CONTROL
AND FLOODING SYSTEM AND PREPARATION METHOD THEREOF
Abstract
The present invention provides a modified nano-graphite particle
three-phase foam profile control and flooding system, which
comprises a liquid phase and a gas phase, wherein the liquid phase
comprises 0.15%-0.35% foaming agent, 0.04-0.1% foam stabilizer, and
water that accounts for the remaining content, the sum of weight
percentages of above components is 100%; a gas-liquid ratio of the
gas phase to the liquid phase is (1-3):1. The foaming agent is
selected from one of alkylsulfopropyl betaine and alkylamidopropyl
betaine or a combination of them. The foam stabilizer is modified
nano-graphite particles in 80-150 nm particle diameter. The present
invention further provides a preparation method of the modified
nano-graphite particle and a preparation method of the three-phase
foam profile control and flooding system. The nano-graphite
particle three-phase foam profile control and flooding system
provided in the present invention can greatly improve the stability
of generated foams, has excellent fluidity control capability, is
low in cost, simple to prepare, and convenient for large-scale
field construction.
Inventors: |
ZHAO; Guang; (Qingdao
Shandong, CN) ; DAI; Caili; (Qingdao Shandong,
CN) ; GU; Chenglin; (Qingdao Shandong, CN) ;
LI; Yuyang; (Qingdao Shandong, CN) ; LV; Yahui;
(Qingdao Shandong, CN) ; YOU; Qing; (Qingdao
Shandong, CN) ; SUN; Yongpeng; (Qingdao Shandong,
CN) ; ZHAO; Mingwei; (Qingdao Shandong, CN) ;
WU; Yining; (Qingdao Shandong, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CHINA UNIVERSITY OF PETROLEUM (EAST CHINA) |
Shandong |
|
CN |
|
|
Assignee: |
CHINA UNIVERSITY OF PETROLEUM (EAST
CHINA)
Shandong
CN
|
Family ID: |
61662410 |
Appl. No.: |
16/040307 |
Filed: |
July 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/594 20130101;
C09K 2208/10 20130101; E21B 43/168 20130101; E21B 43/164 20130101;
E21B 43/20 20130101; C09K 8/94 20130101 |
International
Class: |
C09K 8/594 20060101
C09K008/594; C09K 8/94 20060101 C09K008/94; E21B 43/20 20060101
E21B043/20; E21B 43/16 20060101 E21B043/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2017 |
CN |
201710980124.4 |
Claims
1-9. (canceled)
10. A method of preparing a composition for foam profile control
and flooding, the composition comprising a liquid phase and a gas
phase, wherein: the liquid phase comprises 0.15%-0.35% foaming
agent, 0.04-0.1% foam stabilizer, and water; and a gas-liquid ratio
of the gas phase to the liquid phase is (1-3):1; the method
comprising the following steps: step 1: adding modified
nano-graphite particles into water and stirring to disperse the
nano-graphite particles, to obtain a graphite dispersed solution;
wherein the modified nano-graphite particles are prepared with the
following method: 1) adding dispersed graphite particles having a
15 .mu.m particle diameter into deionized water and stirring for 10
min, to disperse the dispersed graphite particles at room
temperature, to prepare a first graphite dispersed solution; 2)
loading the first graphite dispersed solution into a colloid mill
and shearing the first graphite dispersed solution cyclically for
5-10 min. under a 40-45 Hz shearing condition, to prepare a second
graphite dispersed solution; 3) dispersing the second graphite
dispersed solution by ultrasonic dispersion for 3-6 h, and removing
the supernatant liquid, to obtain a homogeneous graphite dispersed
solution; 4) adding sodium dodecyl sulfate, and stirring at
30-50.degree. C. temperature for 3-6 h, to obtain the modified
nano-graphite particles having a 80-150 nm particle diameter; step
2: adding a foaming agent, and stirring till the foaming agent is
dissolved fully, to obtain a liquid phase; step 3: charging a gas
at (1-3):1 gas-liquid ratio by a foaming device into the liquid
phase, to obtain a modified nano-graphite particle three-phase foam
profile control and flooding system.
11. The method according to claim 10, wherein the stirring time for
dispersion in step 1 is 5-10 min.; and the foaming agent in step 2
is selected from one of alkylsulfopropyl betaine and
alkylamidopropyl betaine or a combination thereof.
12. The method according to claim 11, wherein the foaming agent is
an alkylsulfopropyl betaine and is represented by formula (1):
##STR00005## wherein R is C.sub.12, C.sub.14, or C.sub.16
alkyl.
13. The method according to claim 11, wherein the foaming agent is
an alkylamidopropyl betaine and is represented by formula (2):
##STR00006## wherein R is C.sub.10-C.sub.16 alkyl.
14. The method according to claim 10, wherein the water in the
liquid phase is clean water or treated re-injected water in oil
field.
15. The method according to claim 10, wherein the gas phase is
selected from nitrogen, carbon dioxide and natural gas.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to Chinese Patent
Application No. 201710980124.4, filed on Oct. 19, 2017, and the
entire contents thereof are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention belongs to the field of oil field
chemistry, and particularly relates to a modified nano-graphite
particle three-phase foam profile control and flooding system for
in depth profile control and flooding in oil field and preparation
method of the modified nano-graphite particle three-phase foam
profile control and flooding system.
BACKGROUND OF THE INVENTION
[0003] Long-term water-flooding extraction in oil fields results in
aggravated non-homogeneity of the strata, accelerated water-cut
rising speed and degraded water flooding efficiency or inefficient
circulation in the middle and late stages of oil field
exploitation. Consequently, a great deal of remaining oil in the
strata can't be exploited. Therefore, decreasing the water-cut in
the oil wells is the key to increasing and stabilizing the yield in
the oil fields in in depth exploration of remaining oil in high
water-cut oil reservoirs in the middle and late stages. In recent
years, foam materials have been widely applied in oil fields and
mine sites, owing to their advantages including high apparent
viscosity, reduction ability of oil-water interfacial tension, and
high selectivity (defoamed in oil and stabilized in water), etc.
Foam profile control and flooding systems commonly used in oil
fields mainly include single liquid phase foam system, polymer
enhanced foam system, gel enhanced foam system, and nano-particle
enhanced foam system. A single liquid phase foam system consists of
surfactant and gas (N.sub.2, CO.sub.2), but has poor stability and
is usually applicable to medium-low temperature and medium-low salt
content oil reservoirs. For a polymer enhanced foam system, a
polymer is added in foaming solution, and thereby the thickness of
the liquid films is increased and the drainage speed of the liquid
films is decreased by virtue of the viscosity of the polymer, and
the stability of the foams is improved. However, owing to be
influenced by the injection equipment, shearing stress in pores of
the strata, and physical and chemical properties of the strata, the
viscosity loss of the polymer is severe, and the foam stability of
the polymer is limited. Therefore, a polymer enhanced foam system
is especially not suitable for use in medium-high temperature and
medium-high salt content oil reservoirs. Gel enhanced foams are
formed by polymer, cross-linking agent, foaming agent and gas
(N.sub.2, CO.sub.2), and a gel enhanced foam system utilizes the
strong viscoelastic effect of gel to improve the viscosity of the
external phase and increase the thickness of the liquid films to
realize foam stability and long-time effectiveness, and is usually
applicable to medium-high temperature and medium-high salt content
oil reservoirs. However, the polymer in the gel is also subjected
to the influence of the injection equipment, shearing stress in the
pores of the strata, and physical and chemical properties of the
strata, and consequently the gelation time and gel strength of the
gel are difficult to control and the foam stabilization capability
is limited. The nano-particle enhanced foam system developed
recently utilizes the adsorption effect of the particles to enhance
foam stability, but the foam stabilizing particles are mainly
modified nano-silica particles, and the surface properties of the
nano-particles may vary under the influence of physical and
chemical properties of the strata and long-time erosion of stratum
water. Therefore, the foam stabilization effect is poor. Besides,
nano-silica particles have high density and may produce a
gravitational differentiation effect. Consequently, the foam
stabilization effect of the particles is limited.
Contents of the Invention
[0004] To overcome the drawbacks in the foam profile control and
flooding systems in the prior art, the present invention provides a
modified nano-graphite particle three-phase foam profile control
and flooding system for in depth profile control and flooding for
oil reservoir with high water content in the middle and late stages
and a preparation method of the modified nano-graphite particle
three-phase foam profile control and flooding system. Utilizing the
adsorption characteristic of modified nano-graphite particles, to
improves the stability of the foams by improving the strength of
the liquid films and decreasing the drainage speed of the liquid
films, and thereby exerts the regulation and control capability for
high-permeability strata as far as possible; in addition, utilizing
the oil displacement capability of the foaming agent solution, the
modified nano-graphite particle and the foaming agent attains a
synergistic effect and greatly improves the oil recovery rate.
[0005] To attain the object described above, the present invention
employs the following technical scheme: [0006] a modified
nano-graphite particle three-phase foam profile control and
flooding system, comprising a liquid phase and a gas phase, wherein
the liquid phase comprises a foaming agent, a foam stabilizer, and
water; based on the total mass of the liquid phase, the weight
percentages of the foaming agent is 0.15%-0.35%, the weight
percentages of the foam stabilizer is 0.04-0.1%, the water accounts
for the remaining content in the liquid phase, and the sum of the
weight percentages of the components is 100%; a gas-liquid ratio of
the gas phase to the liquid phase is controlled at (1-3):1.
[0007] Furthermore, the foaming agent above is selected from one of
alkylsulfopropyl betaine and alkylamidopropyl betaine or a
combination of thereof.
[0008] Furthermore, the foam stabilizer above preferably is
modified nano-graphite particles, which are preferably in 80-150 nm
particle diameter.
[0009] Furthermore, the gas phase above preferably is one of
nitrogen, carbon dioxide and natural gas.
[0010] Furthermore, the structural formula of the alkylsulfopropyl
betaine above serving as the foaming agent is represented by the
following formula (1):
##STR00001##
in the formula (1), R is C.sub.12, C.sub.14 or C.sub.16 alkyl.
Furthermore, the structural formula of the alkylamidopropyl betaine
above serving as the foaming agent is represented by the following
formula (2):
##STR00002##
in the formula (2), R is C.sub.10-C.sub.16 alkyl.
[0011] Furthermore, the water in the modified nano-graphite
particle three-phase foam profile control and flooding system is
clean water or treated re-injected water in oil field.
[0012] The present invention further provides a method for
preparing the modified nano-graphite particles, which comprises the
following steps: [0013] adding graphite particles in 15 .mu.m
particle diameter into deionized water and stirring for 10 min. to
disperse the graphite particles at room temperature
(20.+-.5.degree. C.), to prepare graphite dispersed solution;
loading the graphite dispersed solution prepared into a colloid
mill and shearing the graphite dispersed solution cyclically for
5-10 min. under a 40-45 Hz shearing condition, to prepare sheared
graphite dispersed solution; dispersing the obtained sheared
graphite dispersed solution by ultrasonic dispersion for 3-6 h, and
taking the supernatant liquid, to obtain homogeneous graphite
dispersed solution; adding sodium dodecyl sulfate into the obtained
homogeneous graphite dispersed solution, and stirring at
40-50.degree. C. temperature for 3-6 h, to obtain modified graphite
particles in 80-150 nm particle diameter.
[0014] The present invention further provides a method for
preparing the modified nano-graphite particle three-phase foam
profile control and flooding system.
[0015] Adding modified graphite particles prepared with the method
described above in the present invention into water, and stirring
for 10 min. to disperse the modified graphite particles
homogeneously at room temperature (20.+-.5.degree. C.); then adding
one of alkylsulfopropyl betaine and alkylamidopropyl betaine or a
combination of them as a foaming agent, and stirring for 5 min. to
dissolve the foaming agent fully, wherein, the weight percentage of
the modified in graphite particles in the liquid phase is
0.04%-0.1%, the weight percentage of the alkylsulfopropyl betaine
or alkylamidopropyl betaine or the combination of them is
0.15%-0.35%; next, charging the gas at (1-3):1 gas-liquid ratio by
a foaming device into the liquid phase, to obtain the modified
nano-graphite particle three-phase foam profile control and
flooding system.
[0016] Furthermore, the gas in the above preparation method
preferably is one of nitrogen, carbon dioxide and natural gas.
[0017] Furthermore, the structure of the alkylsulfopropyl betaine
serving as the foaming agent is represented by the following
formula (1):
##STR00003##
in the formula (1), R is C.sub.12, C.sub.14 or C.sub.16 alkyl.
[0018] Furthermore, the structure of the alkylamidopropyl betaine
serving as the foaming agent is represented by the following
formula (2):
##STR00004##
in the formula (2), R is C.sub.10-C.sub.16 alkyl.
[0019] Compared with the prior art, the present invention attains
the following beneficial effects:
[0020] (1) The modified nano-graphite particles employed in the
present invention works with one of alkylsulfopropyl betaine,
alkylamidopropyl betaine or a combination of them to attain an
excellent synergistic effect of foam generation and foam
stabilization; after the modified nano-graphite particles are
added, the strength of the liquid films of the foams is increased
and the drainage speed of the liquid films of the foams is
decreased, and thereby the stability of the generated foams is
greatly improved.
[0021] The foam profile control and flooding system attains swept
volume enlargement and oil displacement efficiency improvement
effects before defoaming, and it enters into the in depth portion
of the reservoir by virtue of the self-lubrication feature of the
modified graphite particles after defoaming, and achieves effective
regulation and control of high-permeability flow channels, so that
the subsequent injection pressure is kept at a high level and
thereby further in depth exploitation of remaining oil in oil
reservoirs with high water content in the middle and late stages is
improved.
[0022] (2) The modified nano-graphite particles employed in the
present invention have temperature-resistant and salt-resistant
characteristics, can be dispersed stably in a long time, and
thereby improves the stability of the modified nano-graphite
particle three-phase foams.
[0023] (3) The alkylsulfopropyl betaine or alkylamidopropyl betaine
or the combination of them employed in the present invention has
good temperature-resistant and salt-resistant performance, and
improves the applicability range of the modified nano-graphite
particle three-phase foams to oil reservoirs; besides, it has high
interfacial activity, and can decrease the oil-water interfacial
tension to 10.sup.-2 mN/m order of magnitude, enlarge the swept
volume and improve the oil displacement efficiency as well.
[0024] (4) On one hand, the modified nano-graphite particles
employed in the present invention has high foam stabilization
performance; on the other hand, the modified nano-graphite
particles still achieve effective plugging of high-permeability
flow channels by direct plugging or bridged plugging by virtue of
the plugging characteristic of the particles after the foams
disappear, have high fluidity control capability, and can
remarkably improve the swept volume of the follow-up fluid.
[0025] (5) The modified nano-graphite particle three-phase foam
profile control and flooding system in the present invention is
simple to prepare, the required foaming agent and gas are widely
available and low in price, and the modified nano-graphite
particles are simple to prepare and convenient for large-scale
field construction.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a schematic diagram of the foam stabilization
mechanism of the modified nano-graphite particle three-phase foam
profile control and flooding system;
[0027] FIG. 2 shows the microstructure of the modified
nano-graphite particle three-phase foam profile control and
flooding system in example 1 amplified by 50 times;
[0028] FIG. 3 shows the microstructure of the modified
nano-graphite particle three-phase foam profile control and
flooding system in example 2 amplified by 50 times;
[0029] FIG. 4 shows the microstructure of the modified
nano-graphite particle three-phase foam profile control and
flooding system in example 3 amplified by 100 times;
[0030] FIG. 5 shows the microstructure of the modified
nano-graphite particle three-phase foam profile control and
flooding system in example 4 amplified by 100 times.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0031] To assist those skilled in the art to understand the present
invention better, hereunder the present invention will be further
detailed in embodiments with reference to the accompanying
drawings.
Example 1
[0032] The modified nano-graphite particle three-phase foam profile
control and flooding system comprises: alkylsulfopropyl betaine
foaming agent accounting for 0.2% weight percentage; modified
nano-graphite particles accounting for 0.1% weight percentage; and
water accounting for the remaining weight percentage (99.7%); the
sum of the weight percentages of the components is 100%.
[0033] The modified nano-graphite particles are prepared with the
following method: 200 g graphite particles in 15 .mu.m particle
diameter are added into 800 g deionized water at room temperature
(20.+-.5.degree. C.), and the mixture is stirred for 10 min. to
fully disperse the graphite particles, so that graphite dispersed
solution is obtained; the obtained graphite dispersed solution is
loaded into a colloid mill and sheared cyclically for 10 min. under
a 45 Hz shearing condition, so that sheared graphite dispersed
solution is obtained; the obtained sheared graphite dispersed
solution is dispersed by ultrasonic for 6 h, and the supernatant
liquid is taken, so that 400 g homogeneously dispersed solution at
5% weight percentage is obtained; 20 g sodium dodecyl sulfate is
added into the obtained homogeneously dispersed solution, and the
mixture is stirred at 40.degree. C. for 6 h, so that modified
graphite particles in 80 nm particle diameter are obtained.
[0034] The modified nano-graphite particle three-phase foam profile
control and flooding system is prepared with the following method:
0.04 g alkylsulfopropyl betaine foaming agent and 0.02 g modified
graphite particles are added into 19.92 g water successively at
room temperature (20.+-.5.degree. C.) while stirring, then the
mixture is further stirred for 5 min. to obtain a homogeneous
liquid phase of the modified nano-graphite particle three-phase
foam system. Nitrogen is charged at 3:1 gas-liquid ratio with
Ross-Mile method at 80.degree. C.; the measured foaming volume of
the modified nano-graphite particle three-phase foam profile
control and flooding system is 220 mL, the measured half-life is
330 s, and the oil-water interfacial tension is decreased to
7.6.times.10.sup.-2 mN/m.
Example 2
[0035] The modified nano-graphite particle three-phase foam profile
control and flooding system comprises: alkylsulfopropyl betaine
foaming agent accounting for 0.35% weight percentage; modified
nano-graphite particles accounting for 0.06% weight percentage; and
water accounting for the remaining weight percentage (99.69%); the
sum of the weight percentages of the components is 100%.
[0036] The modified nano-graphite particles are prepared with the
following method: 200 g graphite particles in 15 .mu.m particle
diameter are added into 800 g deionized water at room temperature
(20.+-.5.degree. C.), and the mixture is stirred for 10 min. to
fully disperse the graphite particles, so that graphite dispersed
solution is obtained; the obtained graphite dispersed solution is
loaded into a colloid mill and sheared cyclically for 5 min. under
a 40 Hz shearing condition, so that sheared graphite dispersed
solution is obtained; the obtained sheared graphite dispersed
solution is dispersed by ultrasonic for 4 h, and the supernatant
liquid is taken, so that 400 g homogeneously dispersed solution at
4% weight percentage is obtained; 16 g sodium dodecyl sulfate is
added into the obtained homogeneously dispersed solution, and the
mixture is stirred at 40.degree. C. for 4 h, so that modified
graphite particles in 120 nm particle diameter are obtained.
[0037] The modified nano-graphite particle three-phase foam profile
control and flooding system is prepared with the following method:
0.07 g alkylsulfopropyl betaine foaming agent and 0.012 g modified
graphite particles are added into 19.918 g successively water at
room temperature (20.+-.5.degree. C.) while stirring, then the
mixture is further stirred for 5 min. to obtain a homogeneous
liquid phase of the modified nano-graphite particle three-phase
foam system. Nitrogen is charged at 2:1 gas-liquid ratio with
Ross-Mile method at 80.degree. C.; the measured foaming volume of
the modified nano-graphite particle three-phase foam profile
control and flooding system is 240 mL, the measured half-life is
350 s, and the oil-water interfacial tension is decreased to
4.6.times.10.sup.-2 mN/m.
Example 3
[0038] The modified nano-graphite particle three-phase foam profile
control and flooding system comprises: alkylsulfopropyl betaine
foaming agent accounting for 0.15% weight percentage and
alkylamidopropyl betaine foaming agent accounting for 0.2% weight
percentage; modified nano-graphite particles accounting for 0.08%
weight percentage; and water accounting for the remaining weight
percentage (99.62%); the sum of the weight percentages of the
components is 100%.
[0039] The modified nano-graphite particles are prepared with the
following method: 200 g graphite particles in 15 .mu.m particle
diameter are added into 800 g deionized water at room temperature
(20.+-.5.degree. C.), and the mixture is stirred for 10 min. to
fully disperse the graphite particles, so that graphite dispersed
solution is obtained; the obtained graphite dispersed solution is
loaded into a colloid mill and sheared cyclically for 5 min. under
a 45 Hz shearing condition, so that sheared graphite dispersed
solution is obtained; the obtained sheared graphite dispersed
solution is dispersed by ultrasonic for 5 h, and the supernatant
liquid is taken, so that 400 g homogeneously dispersed solution at
4.5% weight percentage is obtained; 18 g sodium dodecyl sulfate is
added into the obtained homogeneously dispersed solution, and the
mixture is stirred at 30.degree. C. for 6 h, so that modified
graphite particles in 100 nm particle diameter are obtained.
[0040] The modified nano-graphite particle three-phase foam profile
control and flooding system is prepared with the following method:
0.03 g alkylsulfopropyl betaine foaming agent, 0.04 g
alkylamidopropyl betaine foaming agent, and 0.016 g modified
graphite particles are added into 19.914 g water successively at
room temperature (20.+-.5.degree. C.) while stirring, then the
mixture is further stirred for 5 min. to obtain a homogeneous
liquid phase of the modified nano-graphite particle three-phase
foam system. Nitrogen is charged at 3:1 gas-liquid ratio with
Ross-Mile method at 80.degree. C.; the measured foaming volume of
the modified nano-graphite particle three-phase foam profile
control and flooding system is 260 mL, the measured half-life is
365 s, and the oil-water interfacial tension is decreased to
3.2.times.10.sup.-2 mN/m.
Example 4
[0041] The modified nano-graphite particle three-phase foam profile
control and flooding system comprises: alkylsulfopropyl betaine
foaming agent accounting for 0.1% weight percentage and
alkylamidopropyl betaine foaming agent accounting for 0.15% weight
percentage; modified nano-graphite particles accounting for 0.1%
weight percentage; and water accounting for the remaining weight
percentage (99.65%); the sum of the weight percentages of the
components is 100%.
[0042] The modified nano-graphite particles are prepared with the
following method: 200 g graphite particles in 15 .mu.m particle
diameter are added into 800 g deionized water at room temperature
(20.+-.5.degree. C.), and the mixture is stirred for 10 min. to
fully disperse the graphite particles, so that graphite dispersed
solution is obtained; the obtained graphite dispersed solution is
loaded into a colloid mill and sheared cyclically for 10 min. under
a 45 Hz shearing condition, so that sheared graphite dispersed
solution is obtained; the obtained sheared graphite dispersed
solution is dispersed by ultrasonic for 6 h, and the supernatant
liquid is taken, so that 400 g homogeneously dispersed solution at
5% weight percentage is obtained; 20 g sodium dodecyl sulfate is
added into the obtained homogeneously dispersed solution, and the
mixture is stirred at 30.degree. C. for 6 h, so that modified
graphite particles in 85 nm particle diameter are obtained.
[0043] The modified nano-graphite particle three-phase foam profile
control and flooding system is prepared with the following method:
0.01 g alkylsulfopropyl betaine foaming agent, 0.03 g
alkylamidopropyl betaine foaming agent, and 0.02 g modified
graphite particles are added into 19.94 g water successively at
room temperature (20.+-.5.degree. C.) while stirring, then the
mixture is further stirred for 5 min. to obtain a homogeneous
liquid phase of the modified nano-graphite particle three-phase
foam system. Nitrogen is charged at 2:1 gas-liquid ratio with
Ross-Mile method at 80.degree. C.; the measured foaming volume of
the modified nano-graphite particle three-phase foam profile
control and flooding system is 240 mL, the measured half-life is
335 s, and the oil-water interfacial tension is decreased to
4.1.times.10.sup.-2 mN/m.
[0044] While the present invention is described above in
embodiments, the description is exemplary rather than exhaustive,
and the present invention is not limited to the embodiments
disclosed above. It is obvious to those having ordinary skills in
the art that various modifications and alternations can be made
without departing from the scope and spirit of the embodiments
described above. Therefore, the protection scope of the present
invention shall be deemed as the protection scope defined by the
claims only.
* * * * *