Anti-gas channeling plugging composition and application thereof

Abstract

The invention provides an anti-gas channeling plugging composition and application thereof. The anti-gas channeling plugging composition comprises a first system and a second system, the first system comprises a cross-linking monomer, a cross-linking agent, a gelling control agent and an initiator; the second system comprises lauryl sodium sulfate and N, N, N ', N'-tetramethyl-1, 3-propane diamine. The anti-gas channeling plugging composition provided by the invention comprises two systems which have complementary effects, and when the anti-gas channeling plugging composition is used in carbon dioxide flooding exploitation, the plugging rate is high and the application range is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a gas channeling prevention and plugging composition and application thereof. Background Art

[0002] CO2 flooding is one of the important methods to increase the production of low-permeability oil fields. As a supercritical fluid, CO2 is non-toxic and chemically stable. It has good solubility in crude oil and can penetrate into low-permeability areas to increase oil recovery. In field applications, due to factors such as the different mobility ratios between CO2 and crude oil and the heterogeneity of the reservoir, gas channeling is prone to occur during injection and flooding, resulting in gas overflow from the production well, reducing the sweep efficiency of CO2 on crude oil and leading to a decrease in the recovery rate. Among them, natural fractures, artificial fractures and relatively high permeability layers in the reservoir are the main channels for gas channeling. At present, a series of methods such as water-gas alternating injection, gel sealing, foam sealing, chemical precipitation, and CO2 thickening are mainly used to adjust the reservoir to solve the gas channeling problem.

[0003] However, the water-gas alternating injection method is not suitable for oil reservoirs with strong heterogeneity. Frequent water-gas alternating injection will increase the water saturation of the oil reservoir, reduce the contact efficiency between CO2 and crude oil, increase the relative viscosity of crude oil, deteriorate fluidity, and reduce displacement efficiency. In addition, the unstable mobility ratio during the water-gas alternating injection process will corrode the device. The gel plugging method has limited injectability and cannot effectively plug the deep part of the oil reservoir. The foam plugging method is difficult to maintain a certain stability under different temperature and pH conditions, which limits its large-scale development and application in industry. The chemical precipitation method is not only difficult to determine the plugging position, but also difficult to inject in low-permeability oil reservoirs. The CO2 thickening method is costly and difficult to configure. Therefore, it is of great significance to develop a carbon dioxide flooding method with high plugging rate and wide application range. Summary of the invention

[0004] The main purpose of the present invention is to provide a gas channeling prevention and plugging composition, which is used in carbon dioxide flooding and has a high plugging rate and a wide range of applications.

[0005] The present invention also provides a carbon dioxide flooding production method, which uses the above-mentioned anti-gas channeling plugging composition, so the plugging rate is high and the application range is wide.

[0006] In a first aspect, the present invention provides a gas channeling prevention and plugging composition, comprising a first system and a second system;

[0007] The first system includes: a cross-linking monomer, a cross-linking agent, a gelling control agent, and an initiator;

[0008] The second system includes sodium dodecyl sulfate and N,N,N',N'-tetramethyl-1,3-propylenediamine.

[0009] In the gas channeling prevention and plugging composition as described above, the molar ratio of sodium dodecyl sulfate to N,N,N',N'-tetramethyl-1,3-propylenediamine is 1 to 3:1.

[0010] The anti-gas channeling plugging composition as described above, wherein the first system comprises: 3-5% cross-linking monomer, cross-linking agent, 10-15% gelling control agent, 0.1-0.15% initiator, and the balance is deionized water.

[0011] In the gas channeling prevention and plugging composition as described above, the cross-linking monomer is partially hydrolyzed polyacrylamide; the weight average (or number average / Z average) molecular weight of the partially hydrolyzed polyacrylamide is 10 to 30 million, and the degree of hydrolysis is 5 to 50%.

[0012] The anti-gas channeling plugging composition as described above, wherein the cross-linking agent comprises: 0.8-1% sodium dichromate, 1-2% thiourea and 0.1-0.3% sodium thiosulfate; and / or,

[0013] The gelation control agent includes arginine.

[0014] The anti-gas channeling plugging composition as described above further comprises a third system, wherein the third system is a 3-5% persulfate solution.

[0015] In the above-mentioned anti-gas channeling plugging composition, the mass ratio of the first system to the third system is 1 to 5:1.

[0016] In the above-mentioned anti-gas channeling plugging composition, the mass ratio of the first system to the second system is 1 to 5:1.

[0017] In a second aspect, the present invention provides a method for carbon dioxide flooding production, using the above-mentioned anti-gas channeling plugging composition.

[0018] The method as described above further comprises: introducing N2 into the reservoir after mining, and introducing 3-5% persulfate solution for gel breaking treatment.

[0019] The anti-gas channeling plugging composition provided by the present invention comprises two systems, and the two systems have complementary effects. When used in carbon dioxide flooding and mining, the plugging rate is high and the application range is wide. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In a first aspect, the present invention provides a gas channeling prevention and plugging composition, comprising a first system and a second system;

[0022] The first system includes: a cross-linking monomer, a cross-linking agent, a gelling control agent, and an initiator;

[0023] The second system includes sodium dodecyl sulfate and N,N,N',N'-tetramethyl-1,3-propylenediamine.

[0024] It can be understood that there are two main reasons for CO2 gas channeling: one is the natural or artificial fractures in the reservoir, and the other is the relatively high permeability area in the reservoir. To plug the gas channeling channel of the fracture with larger pore throat, a plugging agent with high gelling strength and good stability should be selected; when plugging the high permeability layer with relatively high permeability in the reservoir, the injection performance of the plugging agent should be considered, requiring good injectability and subsequent stable effect in the reservoir; since the anti-gas channeling plugging composition is for CO2 flooding, the anti-gas channeling plugging composition should be able to maintain stable performance in an acidic environment.

[0025] The anti-gas channeling plugging composition provided by the present invention comprises two systems, namely a first system and a second system; wherein the first system comprises: a cross-linking monomer, a cross-linking agent, a gelling control agent, and an initiator; in the presence of the initiator, the cross-linking agent acts to make the cross-linking monomers cross-link with each other, and in the process, the gelling control agent can control the cross-linking of the cross-linking monomers, thereby delaying gelling and providing convenience for injection into the reservoir. The gel system formed by the gelling control agent is particularly suitable for plugging large-scale fractures, for example, natural or artificial fractures with large pore throats.

[0026] The second system includes sodium dodecyl sulfate (SDS) and N,N,N',N'-tetramethyl-1,3-propylenediamine (TMPDA), which is a carbon dioxide responsive system. Before contact with carbon dioxide, the viscosity of its solution is similar to that of water, with low viscosity, good fluidity and good injectability. After contact with carbon dioxide, the viscosity begins to increase, which has a plugging effect and is particularly suitable for plugging areas with relatively high permeability in reservoirs. The viscosity of the second system begins to increase after contact with carbon dioxide. It is speculated that this may be because TMPDA contains a hydrophobic quaternary ammonium salt that can be protonated, and ionization produces H after CO2 dissolves in water. + , where the hydrophobic quaternary ammonium salt and H + The combination is protonated and the quaternary ammonium salt becomes hydrophilic. At this time, the TMPDA molecule is positively charged. Since the SDS molecule is negatively charged, two negatively charged SDS molecules and one positively charged TMPDA undergo molecular "bridging" to form worm-like micelles with high viscosity, thereby increasing the viscosity of the system.

[0027] The anti-gas channeling plugging composition provided by the present invention includes two systems. The first system is a temperature-resistant and salt-resistant high-strength plugging system. Because its colloid has high rigidity, toughness and stability, it has a good plugging effect on fracture-type CO2 gas channeling channels; the second system has good fluidity. When CO2 is passed, it has a good plugging effect on relatively high permeability layers in the reservoir. Therefore, the two systems have complementary effects. When used in carbon dioxide drive production, they have a high plugging rate and a wide range of applications.

[0028] In some embodiments of the present invention, the molar ratio of sodium dodecyl sulfate to N,N,N',N'-tetramethyl-1,3-propylenediamine is 1 to 3:1.

[0029] In the present invention, the molar ratio of sodium dodecyl sulfate (SDS) and N,N,N',N'-tetramethyl-1,3-propylenediamine (TMPDA) in the second system, i.e., the carbon dioxide responsive system, is controlled to be 1 to 3:1, which can meet the requirement of molecular "bridging" between SDS molecules and TMPDA to form worm-like micelles with high viscosity, thereby increasing the viscosity of the system and further achieving a high carbon dioxide plugging rate in the reservoir, especially in the high permeability area.

[0030] In some embodiments of the present invention, the first system includes: 3-5% cross-linking monomer, cross-linking agent, 10-15% gelling control agent, 0.1-0.15% initiator, and the balance is deionized water.

[0031] The first system in the present invention comprises: 3-5% cross-linking monomer, cross-linking agent, 10-15% gelling control agent, 0.1-0.15% initiator, and the balance is deionized water. The content of each component is within a suitable range, so that the first system can be used as a plugging agent, especially when plugging gas channeling channels of cracks with larger pore throats, with a long gelling time, high stability, good injection performance and high economic benefits.

[0032] In some embodiments of the present invention, the cross-linking monomer is partially hydrolyzed polyacrylamide; the weight average (or number average / Z average) molecular weight of the partially hydrolyzed polyacrylamide is 10 to 30 million, and the degree of hydrolysis is 5 to 50%.

[0033] The cross-linking monomer of the first system in the present invention is partially hydrolyzed polyacrylamide (HPAM), and the weight average (or number average / Z average) molecular weight of the partially hydrolyzed polyacrylamide is 10 to 30 million, and the degree of hydrolysis is 5 to 50% (molar percentage). In a suitable range, the partially hydrolyzed polyacrylamide undergoes a cross-linking reaction with the cross-linking agent through its amide group, thereby forming a polymer gel system, and the appropriate weight average molecular weight and degree of hydrolysis can adjust the viscosity of the first system to a suitable range.

[0034] The present invention limits the weight average molecular weight and hydrolysis degree of the cross-linking monomer partially hydrolyzed polyacrylamide of the first system, which can further improve the blocking effect of CO2 gas channeling channels in the reservoir, especially fracture-type CO2 gas channeling channels.

[0035] In some embodiments of the present invention, the cross-linking agent comprises: 0.8-1% sodium dichromate, 1-2% thiourea and 0.1-0.3% sodium thiosulfate; and / or,

[0036] The gelation control agent includes arginine.

[0037] The crosslinking agent in the first system of the present invention comprises: 0.8-1% sodium dichromate, 1-2% thiourea and 0.1-0.3% sodium thiosulfate. 3+ It reacts with carboxylic acid to form a polymer gel system, but the chromium in sodium dichromate is hexavalent. 6+ Need to be reduced to Cr 3+ Compared with the salt of trivalent chromium ion, sodium dichromate is relatively cheap. Thiourea and sodium thiosulfate are both reducing agents, but thiourea alone has poor reduction performance, and sodium thiosulfate is inconvenient to buy and expensive. Thiourea and sodium thiosulfate are used in combination in a certain proportion to achieve better reduction effect and better economic benefits.

[0038] The present invention adds arginine as a gelation control agent to delay the gelation of the crosslinking agent. In the redox reaction environment, arginine has a great influence on Cr 3+ It has chelating ability and can slow down Cr 3+ The time for the carboxylic acid to react with the polymer. The system can delay the gelation and the gel can be stable for 30 days without aging.

[0039] In some embodiments of the present invention, a third system is further included, wherein the third system is a 3-5% persulfate solution.

[0040] The third system of the anti-gas channeling plugging composition of the present invention is a 3-5% persulfate solution, for example, a 3-5% sodium persulfate solution. After the first system and the second system in the plugging composition have achieved plugging of carbon dioxide gas, a 3-5% persulfate solution is added, which can be combined with the Cr in the first system. 3+ The reaction is carried out to destroy the gel structure, thereby achieving gel breaking treatment for the first system.

[0041] The third system in the present invention is a 3-5% persulfate solution, which can achieve gel breaking treatment for the first system, and can prevent the first system from remaining in the reservoir after being injected into the reservoir, causing pollution to the formation environment.

[0042] In some embodiments of the present invention, the mass ratio of the first system to the third system is 1 to 5:1.

[0043] In the present invention, the mass ratio of the first system to the third system in the anti-gas channeling plugging composition is controlled to be 1 to 5:1. In a suitable range, the third system, i.e., 3 to 5% persulfate solution, can be injected into the reservoir to achieve the first system, i.e., HPAM / Cr 3+ The gel-breaking treatment of the system is more thorough, and it can also avoid excessive addition of 3-5% persulfate solution and its retention in the formation, causing pollution to the formation.

[0044] In some embodiments of the present invention, the mass ratio of the first system to the second system is 1 to 5:1.

[0045] In the present invention, the mass ratio of the first system to the second system in the anti-gas channeling plugging composition is controlled to be 1-5:1, within a suitable range, which can further improve the plugging effect on carbon dioxide gas, and the complementary effect of the two is more obvious, which can further improve the plugging rate.

[0046] In a second aspect, the present invention provides a method for carbon dioxide flooding production, using the above-mentioned anti-gas channeling plugging composition.

[0047] In the carbon dioxide flooding production method of the present invention, the anti-gas channeling plugging composition is used to plug carbon dioxide, and the plugging rate is high and the application range is wide.

[0048] In some embodiments of the present invention, after mining, the process further includes: introducing N2 into the reservoir, and / or introducing 3-5% persulfate solution to perform gel breaking treatment.

[0049] After the mining is completed, the present invention introduces N2 into the reservoir to break the gel of the second system, i.e., the carbon dioxide responsive system. After the N2 removes the CO2 in the solution, the quaternary ammonium salt is deprotonated into a tertiary amine, forming spherical micelles with a low initial viscosity. Moreover, this transformation from spherical micelles to worm-like micelles is reversible and can be performed multiple times. The introduction of 3-5% persulfate solution into the reservoir is to break the gel of the first system, i.e., HPAM / Cr 3+ The system was subjected to gel breaking treatment.

[0050] The carbon dioxide flooding method of the present invention has a reversible plugging effect, which can avoid the plugging agent used in the prior art from being left in the reservoir after being injected into the reservoir, causing pollution to the formation environment. 3+ 3% persulfate solution is added into the system as a degumming agent, and the degumming effect is good; the worm-like micelle morphology formed after the carbon dioxide responsive system reacts with CO2 will discharge CO2 out of the system after N2 is introduced, so that the viscosity of the system is reduced, and it can be discharged from the formation like an aqueous solution, and can be returned to the ground after work, realizing harmless operation to the formation.

[0051] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0052] Example 1

[0053] The method of carbon dioxide flooding production in this embodiment comprises the following steps:

[0054] 1) Take a 100 mL beaker and add pure water, add 3% partially hydrolyzed polyacrylamide (HPAM) crystals and stir until completely dissolved, the hydrolysis degree of the partially hydrolyzed polyacrylamide is 25%, and the weight average molecular weight is 10 million, then add a crosslinking agent (containing 0.8% sodium dichromate, 1% thiourea, and 0.1% sodium thiosulfate) until completely dissolved, add 15% amino acid as a gelation control agent, continue to stir until uniformly dispersed, pass nitrogen into the above solution for 30 minutes, add 0.1% ammonium thiosulfate as an initiator and continue to pass nitrogen for 5 minutes to obtain a first system;

[0055] 2) SDS, TMPDA and water were added into a beaker, wherein the molar ratio of SDS to TMPDA was 2:1, recorded as ratio 1, and stirred and dissolved at 55° C. for 6 minutes. The solution system was sealed and allowed to stand at 25° C. for half an hour to stabilize, and the foam in the system was removed to obtain a second system;

[0056] 3) Take out a high-permeability and a low-permeability core, and artificially create cracks in the high-permeability core, and record its weight. Then, vacuum the core to saturate it with water, and record the wet weight to calculate the pore volume of the core. Next, push water at a rate of 0.5mL / min until the pressure stabilizes, record the pressure, and calculate the permeability of the core. Then, inject simulated formation oil at the same rate until the core is saturated to the maximum oil saturation, and record the saturated oil volume to calculate the bound water volume.

[0057] 4) In a high-temperature oven at 70°C, a double-tube parallel core holder was used to displace CO2 at a rate of 1.0 mL / min until CO2 was observed to escape from the outlet. The first system and the second system were both injected at a rate of 1.0 mL / min, wherein the mass ratio of the first system to the second system was 3:1, recorded as ratio 2. After stopping the injection, the core was sealed and left to stand for 20 hours;

[0058] 5) After releasing the injection pressure at the inlet, carry out subsequent CO2 gas drive at a rate of 1.0 mL / min until CO2 leakage is observed at the outlet, and calculate the plugging rate and recovery factor.

[0059] Example 2-19

[0060] The carbon dioxide flooding production method of Example 2-19 is basically the same as that of Example 1, except that one or more items in the production method are changed. Specific results are shown in Table 1-2.

[0061] Embodiment 20

[0062] The method of carbon dioxide flooding and production in Example 20 is basically the same as that in Example 1, except that step 6 is added) N2 is introduced at a rate of 1.0 mL / min, and 3% sodium persulfate solution is introduced at a rate of 1.0 mL / min, wherein the mass ratio of the first system to the 3% sodium persulfate solution is 3:1, for gel breaking treatment.

[0063] Examples 21-22

[0064] The carbon dioxide flooding method of Example 21-22 is basically the same as that of Example 20, except that the concentration of the sodium persulfate solution is changed. The specific results are shown in Table 1-2.

[0065] Comparative Example 1

[0066] The carbon dioxide flooding method of this comparative example is basically the same as that of Example 1, except that only the first system is injected in step 4). Specific results are shown in Table 1-2.

[0067] Comparative Example 2

[0068] The carbon dioxide flooding method of this comparative example is basically the same as that of Example 1, except that only the second system is injected in step 4). Specific results are shown in Table 1-2.

[0069] Comparative Example 3

[0070] The method of carbon dioxide flooding in this comparative example is basically the same as that in Example 1, except that the second system in step 4) includes a small molecule amine compound (DMTA) and an anionic surfactant (NADS). Specific results are shown in Table 1-2.

[0071] Comparative Example 4

[0072] The method of carbon dioxide flooding in this comparative example is basically the same as that in Example 1, except that a gel-type foam plugging agent (mainly composed of polyacrylamide, chromium acetate, sodium dodecylbenzene sulfonate, etc.) is injected in step 4). Specific results are shown in Table 1-2.

[0073] Test example:

[0074] 1. The calculation formula of core plugging rate is: plugging rate (%) = (permeability before plugging - permeability after plugging) / permeability before plugging * 100%;

[0075] The calculation formula of core permeability is:

[0076] Kg: core permeability, μm;

[0077] Q0: gas volume flow rate at the core outlet, mL / s;

[0078] Pa: atmospheric pressure (absolute), MPa;

[0079] L: core length, cm;

[0080] μ: viscosity of carbon dioxide liquid at experimental temperature and atmospheric pressure, MPa;

[0081] A: core cross-sectional area, cm 2 ;

[0082] P1: absolute pressure at the core inlet, MPa;

[0083] P2: Absolute pressure at the core outlet, MPa.

[0084] 2. Testing method for gelling time and gelling strength of the first system: Place the prepared first system in a 60℃ oven. During the constant temperature process in the oven, take it out every 5 days to observe whether it has gelled and test the viscosity. The time when the viscosity is greater than E is the gelling time, and the gelling strength is I.

[0085] After 10 days, the gel viscosity was quickly tested at 70°C.

[0086] The gel strength results are shown in the following table:

[0087] Time / day 10 15 30 40 50 60 Gel strength G I I I I I

[0088] 3. Test method for gelation time and gelation strength of the second system: transfer the prepared second system to a beaker, introduce CO2 gas at a flow rate of 50 mL / min for 2 minutes, and stir the solution system to ensure that the gas and solution are fully mixed to form a CO2-responsive gel system. Then place it in a constant temperature environment of 80°C for 3 days. Observe the gelation time and gelation strength.

[0089] The viscosity of the second system before the introduction of CO2 was tested by a rheometer, and the viscosity of the system was 25.6 mPa s at 80°C. The viscosity of the gel system formed by the introduction of CO2 was 3268 mPa s.

[0090] Table 1

[0091]

[0092]

[0093] Table 2

[0094]

[0095]

[0096] From Table 1-2, it can be seen that compared with the comparative example, the anti-gas channeling plugging composition provided by the present invention includes two systems. The first system is a temperature-resistant and salt-resistant high-strength plugging system. Because its colloid has high rigidity, toughness and stability, it has a good plugging effect, especially for fracture-type CO2 gas channeling channels; the second system has good fluidity. When CO2 is passed, it has a good plugging effect, especially for relatively high permeability layers in the reservoir. Therefore, the two systems have complementary effects. When used in carbon dioxide drive production, the plugging rate is high and the application range is wide.

[0097] From the comparison between Example 1 and Comparative Examples 1-4, it can be seen that the carbon dioxide flooding production method provided by the present invention has a higher plugging rate and a much improved recovery rate.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas channeling blocking composition, characterized in that: It includes the first system and the second system; The first system includes: a cross-linking monomer, a cross-linking agent, a gelling control agent, and an initiator; The second system includes sodium dodecyl sulfate and N,N,N',N'-tetramethyl-1,3-propylenediamine.

2. The anti-gas channeling plugging composition according to claim 1, characterized in that: The molar ratio of the sodium dodecyl sulfate to N,N,N',N'-tetramethyl-1,3-propylenediamine is 1 to 3:

1.

3. The anti-gas channeling plugging composition according to claim 1 or 2, characterized in that: The first system comprises: 3-5% cross-linking monomer, cross-linking agent, 10-15% gelling control agent, 0.1-0.15% initiator, and the balance is deionized water.

4. The anti-gas channeling plugging composition according to claim 3, characterized in that: The cross-linking monomer is partially hydrolyzed polyacrylamide; the partially hydrolyzed polyacrylamide has a molecular weight of 10 million to 30 million and a hydrolysis degree of 5 to 50%.

5. The anti-gas channeling plugging composition according to claim 3 or 4, characterized in that: The cross-linking agent comprises: 0.8-1% sodium dichromate, 1-2% thiourea and 0.1-0.3% sodium thiosulfate; and / or, The gelation control agent includes arginine.

6. The anti-gas channeling plugging composition according to any one of claims 1 to 5, characterized in that: The invention also comprises a third system, wherein the third system is a 3-5% persulfate solution.

7. The anti-gas channeling plugging composition according to claim 6, characterized in that: The mass ratio of the first system to the third system is 1 to 5:

1.

8. The anti-gas channeling plugging composition according to any one of claims 1 to 7, characterized in that: The mass ratio of the first system to the second system is 1 to 5:

1.

9. A method for carbon dioxide flooding production, characterized in that: Use the anti-gas channeling plugging composition described in any one of claims 1 to 8.

10. The method according to claim 9, characterized in that After mining, the method further includes: introducing N2 into the reservoir, and / or introducing 3-5% persulfate solution to perform gel breaking treatment.

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