阅读说明：本技术 一种裂缝性油藏胶结性调剖剂及其应用和使用方法 (Cementing profile control agent for fractured reservoir and application and use method thereof ) 是由 李娟� 郑黎明 于 2020-05-12 设计创作，主要内容包括：本发明涉及油气田开发工程调剖堵水领域,尤其涉及一种裂缝性油藏胶结性调剖剂及其应用和使用方法。本发明的裂缝性油藏胶结性调剖剂,包括独立分装的聚合物水溶液、交联剂水溶液和胶结剂乳液；所述胶结剂乳液由包覆胶结剂的微球乳液和包覆破胶剂的微球乳液混合得到。该胶结性调剖剂具有注入阻力小、封堵效率高、兼具“粘”与“黏”特点、成本低等特点,可适用于裂缝性低渗透油藏调剖堵水。(The invention relates to the field of profile control and water shutoff of oil and gas field development engineering, in particular to a cementing profile control agent for a fractured reservoir and an application and a using method thereof. The cementing profile control agent for the fractured reservoir comprises a polymer aqueous solution, a cross-linking agent aqueous solution and a cementing agent emulsion which are independently packaged; the cementing agent emulsion is obtained by mixing microsphere emulsion coated with a cementing agent and microsphere emulsion coated with a gel breaker. The cementing profile control agent has the characteristics of small injection resistance, high plugging efficiency, adhesion and stickiness, low cost and the like, and is suitable for profile control and water plugging of fractured low-permeability oil reservoirs.)

1. A profile control agent for the cementation of fractured reservoirs comprises a polymer aqueous solution, a cross-linking agent aqueous solution and a cementing agent emulsion which are independently packaged; the cementing agent emulsion is obtained by mixing microsphere emulsion coated with a cementing agent and microsphere emulsion coated with a gel breaker.

2. The fractured reservoir consolidation profile control agent according to claim 1, wherein the concentration of the polymer in the aqueous polymer solution is 800-5000 mg/L, and the polymer comprises one or more of polyacrylamide, acrylamide grafted polymer, ethylene imine polymer, acrylic resin and modified starch.

3. The fractured reservoir cementing profile control agent according to claim 1, wherein the concentration of the cross-linking agent in the cross-linking agent aqueous solution is 30-60 mg/L, and the cross-linking agent comprises one or more of aluminum citrate, aluminum potassium sulfate, chromium chloride, chromium acetate, sodium dichromate, chromium propionate, zirconium oxychloride and N, N' -methylenebisacryloyl.

4. The fractured reservoir consolidation profile control agent of claim 1, wherein the cementing agent in the microsphere emulsion coated with the cementing agent is marble glue, epoxy resin glue AB glue or ethyl cyanoacrylate; the gel breaker in the microsphere emulsion coated with the gel breaker is sodium sulfite, hydrogen peroxide or ammonium persulfate.

5. A fractured reservoir consolidation profile control agent according to claim 4, wherein the preparation method of the consolidating agent emulsion comprises the following steps:

(1) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylene bisacrylamide, a cementing agent and water to obtain a polymer monomer water phase containing the cementing agent; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the polymer monomer water phase containing the cementing agent with the oil phase, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the cementing agent; the whole preparation process of the microsphere emulsion coated with the cementing agent is carried out under the anaerobic condition;

(2) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylenebisacrylamide, a gel breaker and water to obtain a polymer monomer water phase containing the gel breaker; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the water phase and the oil phase of the polymer monomer containing the gel breaker, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the gel breaker;

(3) mixing the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker to obtain a cementing agent emulsion;

the step (1) and the step (2) have no chronological order.

6. The fractured reservoir cementing profile control agent of claim 5, wherein in the step (1), the mass ratio of the acrylamide, the 2-acrylamide-2-methylpropanesulfonic acid, the N, N' -methylenebisacryloyl, the cementing agent and the water is (50-200): 15-20): 1, (5-10): 300-800); the mass ratio of span 80 to tween 60 to white oil is 7:3: 30; the mass ratio of the water phase to the oil phase of the polymer monomer containing the cementing agent is 1: 6; the mass of the vinyl acetate is 5-20% of the mass of the aqueous phase of the polymer monomer containing the cementing agent; the mass of the initiator is 0.001-0.50% of the mass of the aqueous phase of the polymer monomer containing the cementing agent; the temperature of the polymerization reaction is 40-50 ℃, and the time is 5-10 h.

7. The fractured reservoir cementing profile control agent of claim 5, wherein in the step (2), the mass ratio of the acrylamide, the 2-acrylamide-2-methylpropanesulfonic acid, the N, N' -methylenebisacryloyl, the gel breaker and the water is (50-200): 15-20): 1, (5-10): 300-800); the mass ratio of span 80 to tween 60 to white oil is 7:3: 30; the mass ratio of the water phase to the oil phase of the polymer monomer containing the gel breaker is 1: 6; the mass of the vinyl acetate is 5-20% of the mass of the water phase of the polymer monomer containing the gel breaker; the mass of the initiator is 0.001-0.50% of the mass of the aqueous phase of the polymer monomer containing the gel breaker; the temperature of the polymerization reaction is 40-50 ℃, and the time is 5-10 h.

8. A fractured reservoir cementation profile control agent according to claim 5, 6 or 7, wherein the mass ratio of the microsphere emulsion coated with the gel breaker to the microsphere emulsion coated with the cementing agent is 1 (1-3).

9. The use of the fractured reservoir consolidation profile control agent of any one of claims 1 to 8 in the profile control and/or water shutoff of fractured low-permeability reservoirs.

10. The use method of the cementing profile control agent for fractured reservoirs as set forth in any one of claims 1 to 8, comprising the following steps:

the method comprises the steps of cleaning a shaft, sequentially injecting cleaning fluid and first spacer fluid into a stratum, sequentially injecting a polymer aqueous solution, a second spacer fluid, a cross-linking agent aqueous solution, a second spacer fluid, a cementing agent emulsion and a displacing fluid into the stratum by a slug, stopping pumping and waiting for coagulation when the requirement of the total injection amount of the cementitious profile control agent of the fractured reservoir is met, wherein the cleaning fluid, the second spacer fluid and the displacing fluid are all formation injection water, the first spacer fluid is a polymer aqueous solution, the concentration of a polymer in the first spacer fluid is 300-5000 mg/L, and the polymer in the first spacer fluid is the same as the polymer in the polymer aqueous solution in the cementitious profile control agent of the fractured reservoir in kind.

Technical Field

The invention relates to the field of profile control and water shutoff of oil and gas field development engineering, in particular to a cementing profile control agent for a fractured reservoir and an application and a using method thereof.

Background

Fractured low permeability reservoir (permeability less than 50 × 10)^-3μm²) In the water injection development process, the problem that injected water rapidly flows along opened natural cracks and artificial cracks exists, so that the water injection efficiency is reduced, the recovery efficiency is improved, and the difficulty is increased.

At present, the oil reservoirs widely use a high-viscosity and low-viscosity cross-linked polymer plugging system, the high-viscosity cross-linked polymer plugging system has the problems of overlarge viscosity, no injection and accumulation and plugging near a shaft, and the low-viscosity cross-linked polymer plugging system can be injected into the stratum and has certain plugging efficiency, so that the low-viscosity cross-linked polymer plugging system is approved. However, both types of profile control systems essentially utilize polymer monomers and cross-linking agents to form network polymers underground; the reticular polymer is a viscoelastic fluid, but mainly shows the characteristics of high viscosity and smooth surface, expands and contracts by virtue of the elastic-plastic characteristics when a crack is blocked, and the volume of the reticular polymer is increased or reduced along with the opening or closing of the crack. When the injection water pressure gradient is less than the reticulated polymer plug pressure gradient, the injection water cannot flow through the fracture. When the injected water breaks through the cracks containing the reticular polymer, the injected water flows through the internal gaps of the reticular polymer and the gaps between the reticular polymer and the rock. Therefore, the gaps between the reticular polymer with smooth appearance and the rocks are still potential channels for the breakthrough of injected water, and the probability of the breakthrough of the injected water is gradually increased as the reticular polymer generated by the conventional plugging system is decomposed and destroyed.

The characteristics of the plugging system are changed, so that the plugging system has high viscosity and simultaneously has cementing capacity with the surface of rock, namely has the characteristics of adhesion and stickiness, and the water-drive channeling plugging efficiency of the fractured low-permeability oil reservoir can be further improved. At present, a profile control agent system with the cementing characteristic is not available, and a fracture oil reservoir cementing profile control agent with small injection resistance, high plugging efficiency, the 'sticky' and 'sticky' characteristics and low cost is urgently needed.

Disclosure of Invention

The invention aims to provide a cementing profile control agent for a fractured low-permeability reservoir and an application and a using method thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a cementing profile control agent for fractured reservoirs, which comprises a polymer aqueous solution, a cross-linking agent aqueous solution and a cementing agent emulsion which are independently packaged; the cementing agent emulsion is obtained by mixing microsphere emulsion coated with a cementing agent and microsphere emulsion coated with a gel breaker.

Preferably, the concentration of the polymer in the polymer aqueous solution is 800-5000 mg/L, and the polymer comprises one or more of polyacrylamide, acrylamide grafted polymer, ethylene imine polymer, acrylic resin and modified starch.

Preferably, the concentration of the cross-linking agent in the cross-linking agent aqueous solution is 30-60 mg/L, and the cross-linking agent comprises one or more of aluminum citrate, aluminum potassium sulfate, chromium chloride, chromium acetate, sodium dichromate, chromium propionate, zirconium oxychloride and N, N' -methylenebisacryloyl.

Preferably, the cementing agent in the microsphere emulsion coated with the cementing agent is marble glue, epoxy resin glue AB glue or ethyl cyanoacrylate; the gel breaker in the microsphere emulsion coated with the gel breaker is sodium sulfite, hydrogen peroxide or ammonium persulfate.

Preferably, the preparation method of the cementing agent emulsion comprises the following steps:

(1) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylene bisacrylamide, a cementing agent and water to obtain a polymer monomer water phase containing the cementing agent; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the polymer monomer water phase containing the cementing agent with the oil phase, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the cementing agent; the whole preparation process of the microsphere emulsion coated with the cementing agent is carried out under the anaerobic condition;

(2) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylenebisacrylamide, a gel breaker and water to obtain a polymer monomer water phase containing the gel breaker; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the water phase and the oil phase of the polymer monomer containing the gel breaker, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the gel breaker;

(3) mixing the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker to obtain a cementing agent emulsion;

the step (1) and the step (2) have no chronological order.

Preferably, in the step (1), the mass ratio of the acrylamide, the 2-acrylamide-2-methylpropanesulfonic acid, the N, N' -methylenebisacryloyl, the cementing agent and the water is (50-200): (15-20): 1, (5-10): 300-800); the mass ratio of span 80 to tween 60 to white oil is 7:3: 30; the mass ratio of the water phase to the oil phase of the polymer monomer containing the cementing agent is 1: 6; the mass of the vinyl acetate is 5-20% of the mass of the aqueous phase of the polymer monomer containing the cementing agent; the mass of the initiator is 0.001-0.50% of the mass of the aqueous phase of the polymer monomer containing the cementing agent; the temperature of the polymerization reaction is 40-50 ℃, and the time is 5-10 h.

Preferably, in the step (2), the mass ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid to the N, N' -methylenebisacryloyl to the gel breaker to the water is (50-200): (15-20): 1 (5-10): 300-800); the mass ratio of span 80 to tween 60 to white oil is 7:3: 30; the mass ratio of the water phase to the oil phase of the polymer monomer containing the gel breaker is 1: 6; the mass of the vinyl acetate is 5-20% of the mass of the water phase of the polymer monomer containing the gel breaker; the mass of the initiator is 0.001-0.50% of the mass of the aqueous phase of the polymer monomer containing the gel breaker; the temperature of the polymerization reaction is 40-50 ℃, and the time is 5-10 h.

Preferably, the mass ratio of the microsphere emulsion coated with the gel breaker to the microsphere emulsion coated with the cementing agent is 1 (1-3).

The invention provides application of the cementing profile control agent for fractured reservoirs in the scheme in profile control and/or water shutoff of fractured low-permeability reservoirs.

The invention provides a use method of the cementing profile control agent for the fractured reservoir in the scheme, which comprises the following steps:

the method comprises the steps of cleaning a shaft, sequentially injecting cleaning fluid and first spacer fluid into a stratum, sequentially injecting a polymer aqueous solution, a second spacer fluid, a cross-linking agent aqueous solution, a second spacer fluid, a cementing agent emulsion and a displacing fluid into the stratum by a section plug, stopping pumping and waiting for coagulation when the requirement of the total injection amount of the fractured reservoir cementing profile control agent is met, wherein the cleaning fluid, the second spacer fluid and the displacing fluid are all formation injection water, the first spacer fluid is a low-concentration polymer solution, the concentration of a polymer in the first spacer fluid is 300-5000 mg/L, and the polymer in the first spacer fluid is the same as the polymer in the fractured reservoir cementing profile control agent in type.

The invention provides a cementing profile control agent for fractured reservoirs, which comprises a polymer aqueous solution, a cross-linking agent aqueous solution and a cementing agent emulsion which are independently packaged; the cementing agent emulsion is obtained by mixing microsphere emulsion coated with a cementing agent and microsphere emulsion coated with a gel breaker.

The cementing agent emulsion disclosed by the invention expands after being injected into a stratum, the gel breaker naturally swells out of the microsphere emulsion, the gel is broken under the action of the gel breaker for 4-12 hours to release the cementing agent in the microsphere emulsion, the cementing agent is displaced by injected water and gradually contacts and mixes with a polymer aqueous solution and a cross-linking agent aqueous solution in pores of the stratum, the polymer aqueous solution and the cross-linking agent aqueous solution are polymerized to form a net-shaped polymer, and the released cementing agent is filled between the net-shaped polymer and a fracture wall, so that the net-shaped polymer with a smooth surface has the characteristics of adhesion and stickiness, the injected water is forced to hardly pass through gaps between the net-shaped polymer and rocks, and the water-drive channeling plugging efficiency of a fractured low-permeability reservoir is improved. The cementing agent emulsion adopted by the invention is obtained by mixing the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker, so that the cementing agent is coated in advance, and the emulsion is injected into the stratum by an emulsion injection mode, thereby reducing the injection resistance. In addition, the invention utilizes the gel breaker to break the gel of the microsphere emulsion coated with the cementing agent, and the performance of the cementing agent is not damaged while the cementing agent is released.

The invention provides a using method of a cementing profile control agent of a fractured reservoir.

Drawings

FIG. 1 is a flow chart illustrating the use of the fracture reservoir consolidation profile control agent of the present invention.

Detailed Description

The invention provides a cementing profile control agent for fractured reservoirs, which comprises a polymer aqueous solution, a cross-linking agent aqueous solution and a cementing agent emulsion which are independently packaged; the cementing agent emulsion is obtained by mixing microsphere emulsion coated with a cementing agent and microsphere emulsion coated with a gel breaker.

In the present invention, the starting materials for the preparation are all commercially available products well known in the art, unless otherwise specified.

The fracture oil reservoir cementing profile control agent provided by the invention comprises a polymer aqueous solution, the concentration of a polymer in the polymer aqueous solution is preferably 800-5000 mg/L, more preferably 1000-4000 mg/L, the polymer comprises one or more of polyacrylamide (in the embodiment of the invention, partially hydrolyzed polyacrylamide), acrylamide grafted polymer, ethylene imine polymer, acrylic resin and modified starch, and when the polymer comprises a plurality of polymers, the proportion of each polymer is not particularly required, and any proportion can be adopted.

The fractured reservoir cementing profile control agent provided by the invention comprises a cross-linking agent aqueous solution, the concentration of the cross-linking agent in the cross-linking agent aqueous solution is preferably 30-60 mg/L, more preferably 40-50 mg/L, the cross-linking agent preferably comprises one or more of aluminum citrate, aluminum potassium sulfate, chromium chloride, chromium acetate, sodium dichromate, chromium propionate, zirconium oxychloride and N, N' -methylenebisacryloyl, and when the cross-linking agent comprises a plurality of cross-linking agents, the ratio of the cross-linking agents is not particularly required, and any ratio can be selected.

After the polymer aqueous solution and the cross-linking agent aqueous solution are injected into a stratum, a cross-linking polymerization reaction is carried out to obtain a network polymer for plugging cracks.

The cementing profile control agent for the fractured reservoir provided by the invention comprises a cementing agent emulsion, wherein the cementing agent emulsion is obtained by mixing a microsphere emulsion coated with a cementing agent and a microsphere emulsion coated with a gel breaker. In the invention, the cementing agent in the microsphere emulsion coated with the cementing agent is preferably marble glue, epoxy resin glue AB glue or ethyl cyanoacrylate; the solids content of the marble glue is preferably less than 4%. In the invention, the gel breaker in the microsphere emulsion coated with the gel breaker is preferably sodium sulfite, hydrogen peroxide or ammonium persulfate.

In the present invention, the method for preparing the cement emulsion preferably comprises the following steps:

(1) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylene bisacrylamide, a cementing agent and water to obtain a polymer monomer water phase containing the cementing agent; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the polymer monomer water phase containing the cementing agent with the oil phase, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the cementing agent; the whole preparation process of the microsphere emulsion coated with the cementing agent is carried out under the anaerobic condition;

(2) mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylenebisacrylamide, a gel breaker and water to obtain a polymer monomer water phase containing the gel breaker; mixing span 80, tween 60 and white oil to obtain an oil phase; mixing the water phase and the oil phase of the polymer monomer containing the gel breaker, adding vinyl acetate and an initiator into the obtained mixed system, and carrying out polymerization reaction to obtain a microsphere emulsion coated with the gel breaker;

(3) mixing the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker to obtain a cementing agent emulsion;

the step (1) and the step (2) have no chronological order.

The preparation of the binder-coated microsphere emulsion will be described first.

The invention mixes acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylene bisacrylamide, a cementing agent and water under an anaerobic condition to obtain a polymer monomer aqueous phase containing the cementing agent. In the invention, the mass ratio of the Acrylamide (AM), the 2-acrylamide-2-methylpropanesulfonic Acid (AMPS), the N, N' -Methylenebisacryloyl (MBA), the cementing agent and the water is preferably (50-200): 15-20): 1, (5-10): 300-800), more preferably (55-150): 16-19): 1, (6-10): 300-700, and most preferably 57:19:1:10: 300. In the present invention, the mixing process is preferably: introducing nitrogen into a three-neck flask to remove oxygen for 10min under the condition of water bath at the temperature of 30-40 ℃, sequentially adding Acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic Acid (AMPS), N' -Methylene Bisacryloyl (MBA) and a cementing agent into water in the three-neck flask, and stirring to obtain a polymer monomer water phase containing the cementing agent.

In the invention, span 80, tween 60 and white oil are mixed under an anaerobic condition to obtain an oil phase. In the invention, the mass ratio of span 80, tween 60 and white oil is preferably 7:3: 30. The mixing process of the present invention is preferably as follows: and (3) introducing nitrogen into the three-neck flask to remove oxygen for 10min under the water bath condition of 30-40 ℃, and then adding span 80, tween 60 and white oil and uniformly mixing.

After obtaining the polymer monomer water phase and the oil phase containing the cementing agent, the invention mixes the polymer monomer water phase and the oil phase containing the cementing agent under the anaerobic condition, adds vinyl acetate and an initiator into the obtained mixed system, and carries out polymerization reaction to obtain the microsphere emulsion coated with the cementing agent.

In the present invention, the mixing process is preferably: and (3) connecting the three-neck flask containing the polymer monomer water phase containing the cementing agent with the three-neck flask containing the oil phase by using a hose, adding the polymer monomer water phase containing the cementing agent into the oil phase within 30min by using a liquid discharge method, and uniformly stirring and mixing to obtain a mixed system. The invention adopts a liquid discharge method and hose connection, and aims to keep anaerobic condition by introducing nitrogen in advance to remove oxygen when preparing oil phase and polymer monomer water phase containing cementing agent, so as to prevent air from being mixed in the mixing process to cause the solidification of the cementing agent.

After a mixed system is obtained, vinyl acetate and an initiator are added into the mixed system to carry out polymerization reaction, so that the microsphere emulsion coated with the cementing agent is obtained. In the invention, the mass of the vinyl acetate (VAc) is preferably 5-20% of the mass of the aqueous phase of the polymer monomer containing the binding agent, and more preferably 10-20%; the mass of the initiator is preferably 0.001-0.50%, more preferably 0.01-0.45%, and even more preferably 0.02-0.04% of the mass of the aqueous phase of the polymer monomer containing the binding agent. In the present invention, the initiator is preferably sodium sulfite.

In the invention, the temperature of the polymerization reaction is preferably 40-50 ℃, and more preferably 45 ℃; the time is preferably 5 to 10 hours, and more preferably 6 to 9 hours. In the present invention, the polymerization reaction is preferably carried out under water bath conditions. In the polymerization reaction process, Acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic Acid (AMPS), N' -Methylenebisacryloyl (MBA) and vinyl acetate (VAc) are polymerized under the action of an initiator to generate a vinyl acetate-acrylamide polymer, and a cementing agent is coated by the polymer to form a microsphere emulsion coated with the cementing agent.

The preparation of the breaker coated microsphere emulsion is described below.

The preparation method comprises the steps of mixing acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N' -methylenebisacrylamide, a gel breaker and water to obtain a polymer monomer water phase containing the gel breaker. In the invention, the mass ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid to the N, N' -methylenebisacryloyl to the gel breaker to the water is preferably (50-200): 15-20): 1 (5-10): 300-800), more preferably (55-150): 16-19): 1 (6-10): 300-700, and most preferably 57:19:1:10: 300. The invention has no special requirements on the mixing process, and any mode capable of uniformly mixing can be adopted.

The invention mixes span 80, tween 60 and white oil to obtain oil phase. In the invention, the mass ratio of span 80, tween 60 and white oil is preferably 7:3: 30. The invention has no special requirements on the mixing process, and any mode capable of uniformly mixing can be adopted.

After a polymer monomer water phase and an oil phase containing the gel breaker are obtained, the polymer monomer water phase and the oil phase containing the gel breaker are mixed, vinyl acetate and an initiator are added into the obtained mixed system to carry out polymerization reaction, and the microsphere emulsion coated with the gel breaker is obtained.

The present invention preferably mixes the aqueous phase of the polymer monomer containing the breaker dropwise into the oil phase to ensure more uniform mixing. The invention has no special requirement on the dropping speed, and ensures that the materials are uniformly mixed.

After a mixed system is obtained, vinyl acetate and an initiator are added into the mixed system to carry out polymerization reaction, so that the microsphere emulsion coated with the gel breaker is obtained. In the invention, the mass of the vinyl acetate (VAc) is preferably 5-20% of the mass of the aqueous phase of the polymer monomer containing the gel breaker, and more preferably 10-20%; the mass of the initiator is preferably 0.001-0.50%, more preferably 0.01-0.45%, and even more preferably 0.02-0.04% of the mass of the aqueous phase of the polymer monomer containing the gel breaker. In the present invention, the initiator is preferably sodium sulfite.

In the invention, the temperature of the polymerization reaction is preferably 40-50 ℃, and more preferably 45 ℃; the time is preferably 5 to 10 hours, and more preferably 6 to 9 hours. In the present invention, the polymerization reaction is preferably carried out under water bath conditions. In the polymerization reaction process, Acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic Acid (AMPS), N' -Methylenebisacryloyl (MBA) and vinyl acetate (VAc) are polymerized under the action of an initiator to generate a vinyl acetate-acrylamide polymer, and the gel breaker agent is coated by the polymer to form the microsphere emulsion coated with the gel breaker.

The invention has no special requirements on the preparation sequence of the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker, and the microsphere emulsion coated with the cementing agent or the microsphere emulsion coated with the gel breaker can be prepared firstly.

After obtaining the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker, the invention mixes the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker to obtain the cementing agent emulsion. In the invention, the mass ratio of the microsphere emulsion coated with the gel breaker to the microsphere emulsion coated with the cementing agent is preferably 1 (1-3), and more preferably 1 (1.5-2.5). The invention has no special requirements on the mixing process, and any mode capable of uniformly mixing can be adopted.

The cementing agent emulsion disclosed by the invention expands after being injected into a stratum, the gel is broken under the action of the gel breaker for 4-12 hours to release the cementing agent in the emulsion, the cementing agent is displaced by injected water and is gradually contacted and mixed with a polymer aqueous solution and a cross-linking agent aqueous solution in pores of the stratum, the polymer aqueous solution and the cross-linking agent aqueous solution are polymerized to form a reticular polymer, and the released cementing agent is filled between the reticular polymer and a crack wall to improve the characteristics of the reticular polymer, so that the reticular polymer with a smooth surface has the characteristics of adhesion and stickiness, the injected water is forced to hardly pass through gaps between the reticular polymer and rocks, and the water-drive channeling plugging efficiency of a fractured low-permeability reservoir is improved. The cementing agent emulsion adopted by the invention is obtained by mixing the microsphere emulsion coated with the cementing agent and the microsphere emulsion coated with the gel breaker, so that the cementing agent is coated in advance, and the emulsion is injected into the stratum by an emulsion injection mode, thereby reducing the injection resistance. In addition, the invention utilizes the gel breaker to break the gel of the microsphere emulsion coated with the cementing agent, and the performance of the cementing agent is not damaged while the cementing agent is released.

The cementing agent emulsion of the invention is prepared at present and has better use efficiency.

The invention provides the application of the cementing profile control agent for fractured reservoirs in the scheme in the profile control and/or water shutoff of the fractured low-permeability reservoirs, and in the invention, the matrix porosity of the fractured low-permeability reservoirs is preferably lower than 50 × 10^-3μm²And natural cracks develop in the rock, part of the cracks are openable cracks, and the opening degree of the cracks is increased along with the increase of the fluid pressure in the cracks.

The invention provides a use method of the cementing profile control agent for the fractured reservoir in the scheme, which comprises the following steps:

the method comprises the steps of cleaning a shaft, sequentially injecting cleaning fluid and first spacer fluid into a stratum, sequentially injecting a polymer aqueous solution, a second spacer fluid, a cross-linking agent aqueous solution, a second spacer fluid, a cementing agent emulsion and a displacing fluid into the stratum by a section plug, stopping pumping and waiting for coagulation when the requirement of the total injection amount of the fractured reservoir cementing profile control agent is met, wherein the cleaning fluid, the second spacer fluid and the displacing fluid are all formation injection water, the first spacer fluid is a low-concentration polymer solution, the concentration of a polymer in the first spacer fluid is 300-5000 mg/L, and the polymer in the first spacer fluid is the same as the polymer in the fractured reservoir cementing profile control agent in type.

The cementing profile control agent of the fractured reservoir is suitable for profile control and/or water shutoff of the fractured low-permeability reservoir, and the matrix porosity of the fractured low-permeability reservoir is preferably lower than 50 × 10^-3μm²Natural cracks develop in the rock, part of cracks can be opened, and the opening degree is increased along with the increase of the fluid pressure in the cracks; the cementing agent of the invention is not suitable for wells or strata which are subjected to surfactant flooding and organic solvent and multi-element thermal fluid injection in the early stage due to the limitation of the characteristics of the cementing agent.

After well selection and layer selection, the invention prepares polymer aqueous solution and cross-linking agent aqueous solution according to the designed injection total amount of the cementing profile control agent of the fractured reservoir, prepares each monomer aqueous phase and oil phase required by the preparation of the cementing agent emulsion, and waits for 3 h-1 d for the curing of the polymer aqueous solution. In order to prevent the early swelling of the emulsion microspheres of the cementing agent, the water phase and the oil phase of each monomer for preparing the emulsion of the cementing agent are mixed for 0.5 to 1 hour before the emulsion of the cementing agent is injected into the stratum, and the reaction is initiated to prepare the emulsion of the cementing agent.

The present invention preferably incorporates an antioxidant into the aqueous polymer solution for removing dissolved oxygen from the aqueous polymer solution, thereby preventing the gel effect and the use time from being reduced. In the present invention, the antioxidant is preferably sodium thiosulfate or thiourea. The doping amount of the antioxidant is preferably 0.5-2% of the mass of water in the polymer water solution.

The method for calculating the total design injection amount of the profile control agent for the fractured reservoir has no special requirements, and can be calculated by adopting a method known in the field.

After preparation of each component of the cementing profile control agent of the fractured reservoir is finished, the method cleans a shaft, and then injects cleaning fluid and first spacer fluid into a stratum. The invention has no special requirement on the cleaning mode of the shaft, and the cleaning mode which is well known in the field can be adopted. The invention preferably utilizes water to clean the shaft until the liquid returned from the well head is clean water. When the shaft is cleaned, if obvious blockage is found in the underground, the invention preferably adopts chlorine dioxide to remove the blockage, the chlorine dioxide is soaked for 1 day and then reversely circulated to discharge dirt out of the ground, and then the shaft is continuously cleaned by water until the liquid returned from the well mouth is clean water.

The method comprises the steps of sequentially injecting a cleaning solution and a first spacer fluid into a stratum after cleaning of a shaft is finished, wherein the cleaning solution is stratum injection water, the concentration of a polymer in the first spacer fluid is 300-5000 mg/L, and is preferably smaller than the concentration of a polymer aqueous solution in a fractured reservoir cementing profile control agent, the polymer in the first spacer fluid is the same as the polymer in the polymer aqueous solution in the fractured reservoir cementing profile control agent in type, the injection process has no special requirement, and the well-known injection process in the field can be adopted.

After a cleaning solution and a first spacer fluid are injected into a stratum, a polymer aqueous solution, a second spacer fluid, a cross-linking agent aqueous solution, a second spacer fluid, a cementing agent emulsion and a displacing fluid are sequentially injected into the stratum by a segmented plug, and when the requirement of the total injection amount of the cementing profile control agent of a fractured reservoir is met, a pump is stopped for waiting for setting; and the second spacer fluid and the displacing fluid are both formation injection water. In the invention, the mass of the polymer in the polymer aqueous solution is 0.1-0.3% of the total injection amount of the cementing profile control agent of the fractured reservoir; the mass ratio of the polymer in the polymer aqueous solution, the cross-linking agent in the cross-linking agent aqueous solution, the cementing agent in the cementing agent emulsion and the gel breaker is preferably (30-100): 1: (10-50): (1-10). In the present invention, the injection speeds of the respective components are preferably each less than 1m³/h。

In the invention, when the fracture development density of the profile control stratum is high or the channeling degree between oil wells and water wells is high, the method preferably injects nano microspheres or short fiber-containing slugs into the stratum, partially plugs the large pore throat of partial channeling in advance, and then injects the cementing profile control agent of the fractured oil reservoir, so as to prevent the subsequent injection of polymer solution and cross-linking agent solution from fingering and reduce the use efficiency of the cementing profile control agent. The invention has no special requirements on the nano microspheres and the short fibers, and can adopt the nano microspheres and the short fibers which are well known in the field.

FIG. 1 is a flow chart illustrating the use of the fracture reservoir consolidation profile control agent of the present invention. The method comprises the steps of selecting a well and a stratum, preparing components of a cementing profile control agent, cleaning a shaft, and injecting cleaning fluid and first spacer fluid (a preposed plugging slug) into a stratum; and then preparing cementing agent emulsion, injecting the cementing agent into the fractured reservoir by a segmented plug, and completing the plugging of the water-drive channeling channel of the fractured low-permeability reservoir.

The following will explain the cementing profile control agent for fractured reservoirs and the application and use method thereof in detail with reference to the examples, but they should not be construed as limiting the scope of the invention.