Anti-swelling shrinkage agent for oilfield water injection and preparation method of anti-swelling shrinkage agent

Abstract

The invention relates to the technical field of oilfield development, in particular to an anti-swelling shrinkage agent for oilfield water injection and a preparation method of the anti-swelling shrinkage agent. The invention relates to an anti-swelling shrinkage agent for oilfield water injection. The anti-swelling shrinkage agent is prepared from the following raw materials in parts by weight: 5-10 parts of oligomeric quaternary ammonium salt, 5-20 parts of polyether amine, 1-10 parts of an organic-inorganic complexing agent, 0.5-3 parts of a cross-linking agent, 0.05-1 part of an initiator, 1-10 parts of inorganic salt, 0.05-0.25 part of a regulator and 50-400 parts of water. According to the prepared anti-swelling shrinkage agent for oilfield water injection, through the synergistic effect of all the components, long-acting anti-swelling and shrinkage repair are achieved, and the environmental adaptability and comprehensive performance of the anti-swelling shrinkage agent are improved.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and more specifically, to an anti-swelling and anti-expansion agent for oilfield water injection and its preparation method. Background Technology

[0002] Water injection is a crucial part of the common oilfield development process both domestically and internationally. Injecting water into the reservoir can compensate for losses caused by oil and gas extraction, replenish formation energy, maintain formation pressure, and simultaneously push crude oil towards the well, thereby increasing crude oil production. However, long-term water injection can lead to hydration, expansion, dispersion, and migration of clay in water-sensitive reservoirs, further narrowing or even clogging reservoir channels, resulting in increased injection pressure and reduced oil production. Over the years, the development, improvement, and application of anti-swelling and anti-shrinkage agents have, to some extent, solved the problem of insufficient water injection in oilfields.

[0003] In oilfield development, not only is formation protection necessary, but in many cases, repair of formations that have already experienced clay swelling is also required. Inorganic salt anti-swelling agents have a short effective period, and high-valence metal ions easily precipitate in the formation; cationic surfactants can cause wetting reversal on water-wettable sandstone surfaces. Cationic polymers are currently the most widely used clay swelling inhibitors. Conventional anti-swelling agents are ineffective or have minimal effect on formations that have already experienced clay swelling.

[0004] The existing technology has the following problems: conventional anti-swelling agents (such as cationic polymers) are prone to decomposition and failure during steam injection thermal recovery (>150℃). Organic macromolecular anti-swelling agents (such as polymers) are easily adsorbed on the clay surface, leading to a further decrease in the permeability of low-permeability formations. Summary of the Invention

[0005] This invention provides an anti-swelling and anti-shrinkage agent for oilfield water injection and its preparation method. The prepared anti-swelling and anti-shrinkage agent for oilfield water injection achieves long-term anti-swelling and anti-shrinkage repair through the synergistic effect of its various components, thereby improving the environmental adaptability and comprehensive performance of the anti-swelling and anti-shrinkage agent.

[0006] In a first aspect, the present invention provides an anti-swelling and anti-shrinkage agent for oilfield water injection, which is prepared from the following raw materials: 5-10 parts of oligomeric quaternary ammonium salt, 5-20 parts of polyetheramine, 1-10 parts of organic-inorganic composite agent, 0.5-3 parts of crosslinking agent, 0.05-1 part of initiator, 1-10 parts of inorganic salt, 0.05-0.25 parts of regulator, and 50-400 parts of water.

[0007] Preferably, the organic-inorganic composite agent comprises chitosan-modified cationic emulsion polymer and potassium chloride, wherein the mass ratio of chitosan-modified cationic emulsion polymer to potassium chloride is 1 to 3:1.

[0008] Preferably, the chitosan-modified cationic emulsion polymer is prepared by introducing chitosan as a polymerizing monomer using methacryloyloxyethyltrimethylammonium chloride, acrylamide, and N,N-dimethylacrylamide. The mass ratio of methacryloyloxyethyltrimethylammonium chloride, acrylamide, N,N-dimethylacrylamide, and chitosan is 1:2-3:1-2:1-3.

[0009] Preferably, the oligomeric quaternary ammonium salt is prepared from tetramethylethylenediamine and ethylene dibromide, wherein the molar ratio of tetramethylethylenediamine to ethylene dibromide is 1:2 to 3.

[0010] Preferably, the crosslinking agent is one or more of N,N-dimethylethylacrylamide ammonium chloride, 2-alkyl-4-vinylbenzenesulfonate sodium copolymer, ethylene glycol diallyl ether, propylene glycol diallyl ether, and butanediol diallyl ether.

[0011] Preferably, the initiator is one or more selected from cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, dodecyl peroxide, azobisisobutyronitrile, potassium persulfate, sodium persulfate, potassium persulfate-potassium bisulfite, and ammonium persulfate.

[0012] Preferably, the inorganic salt is one or more of sodium sulfate, sodium chloride, potassium chloride, magnesium chloride, magnesium sulfate, and ammonium chloride.

[0013] Preferably, the regulator is one or more of n-butanethiol, tert-butanethiol, sodium hypophosphite, and carbon tetrabromide.

[0014] Secondly, the present invention provides a method for preparing an anti-swelling and anti-expansion agent for oilfield water injection, comprising the following steps: (1) Mix polyetheramine, organic-inorganic composite agent, initiator, crosslinking agent and water, and carry out the reaction after mixing evenly; (2) Mix the oligomerized quaternary ammonium salt, inorganic salt, regulator and the reaction stream obtained in step (1) at a mixing temperature of 30-80℃ and a reaction time of 1-5h to obtain an anti-swelling agent for oilfield water injection.

[0015] Preferably, in step (1), the mixing reaction temperature is 40–80°C.

[0016] In summary, the present invention has the following beneficial effects: 0. The oligomeric quaternary ammonium salts in this invention are cationic compounds with four hydrocarbon-substituted nitrogen atoms, commonly used in oilfield chemicals. They are chemically readily soluble in water, exhibit good water solubility and stability, strong adaptability to pH changes, good thermal stability, strong alkalinity, and stability in both acidic and alkaline media. Furthermore, quaternary ammonium salts possess excellent electrochemical properties and can be used as electrolytes. Quaternary ammonium salts offer environmental advantages in oilfield chemicals, being biodegradable and helping to reduce environmental pollution. Polyetheramines can be used as oil displacement agents, reducing oil-water interfacial tension and making it easier for oil originally adhering to pores to separate from the pore walls, thereby improving oil recovery. In oilfield development, polyetheramines can be used as anti-pore pressure expansion agents; by injecting polyetheramine solutions, the pressure on oil well productivity recovery can be effectively reduced.

[0017] 2. The mechanism of action of the crosslinking agent in the anti-swelling and anti-shrinkage agent of this invention is mainly reflected in its regulation of the polymer network structure. The crosslinking agent reacts with polyols to form additional crosslinks or extend polymer chains, thereby increasing the crosslinking density of the polymer matrix and enhancing its stiffness, strength, and dimensional stability. The effect of the initiator on the performance of the anti-swelling and anti-shrinkage agent is mainly reflected in its dosage affecting the polymer's molecular weight, crosslinking density, viscosity, and water absorption and swelling properties.

[0018] 3. This invention's anti-swelling and anti-shrinkage agent achieves anti-swelling, anti-swelling, and reservoir protection through the complementary functions of its organic-inorganic composite components, the regulation of microstructure via cross-linking networks, and environmental response design. By inhibiting the expansion and contraction of clay minerals in the formation, it indirectly maintains the integrity and efficiency of the pipeline system. In particular, the synergistic effect of the organic-inorganic composite and solvent resolves the contradiction between the anti-swelling rate and long-term effectiveness of traditional agents.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0021] Example Example 1 An anti-swelling and anti-shrinkage agent for oilfield water injection is prepared from the following raw materials: 5 parts of oligomeric quaternary ammonium salt, 5 parts of polyetheramine, 1 part of organic-inorganic composite agent, 0.5 parts of crosslinking agent, 0.05 parts of initiator, 1 part of inorganic salt, 0.05 parts of regulator, and 50 parts of water.

[0022] The organic-inorganic composite agent includes chitosan-modified cationic emulsion polymer and potassium chloride, with a mass ratio of 1:1.

[0023] The chitosan-modified cationic emulsion polymer was prepared by introducing chitosan as a polymerizing monomer, using methacryloyloxyethyltrimethylammonium chloride, acrylamide, and N,N-dimethylacrylamide as polymerizing monomers; the mass ratio of methacryloyloxyethyltrimethylammonium chloride, acrylamide, N,N-dimethylacrylamide, and chitosan was 1:2:1:1.

[0024] The oligomeric quaternary ammonium salts are prepared from tetramethylethylenediamine and ethylene dibromide, with a molar ratio of 1:2 between the two.

[0025] The crosslinking agent is N,N-dimethylethylacrylamide ammonium chloride; the initiator is cumene hydroperoxide; the inorganic salt is sodium sulfate; and the regulator is n-butanethiol.

[0026] A method for preparing an anti-swelling and anti-shrinkage agent for oilfield water injection includes the following steps: (1) Mix polyetheramine, organic-inorganic composite agent, initiator, crosslinking agent and water, and react after mixing evenly; the reaction temperature is 40℃.

[0027] (2) Mix the oligomerized quaternary ammonium salt, inorganic salt, regulator and the reaction stream obtained in step (1) at a mixing temperature of 30°C and a reaction time of 2 hours to obtain an anti-swelling agent for oilfield water injection.

[0028] Example 2 An anti-swelling and anti-shrinkage agent for oilfield water injection is prepared from the following raw materials: 8 parts of oligomeric quaternary ammonium salt, 15 parts of polyetheramine, 5 parts of organic-inorganic composite agent, 2.1 parts of crosslinking agent, 0.5 parts of initiator, 5 parts of inorganic salt, 0.15 parts of regulator, and 200 parts of water.

[0029] The organic-inorganic composite agent includes chitosan-modified cationic emulsion polymer and potassium chloride, with a mass ratio of chitosan-modified cationic emulsion polymer to potassium chloride of 2:1.

[0030] The chitosan-modified cationic emulsion polymer was prepared by introducing chitosan as a polymerizing monomer, using methacryloyloxyethyltrimethylammonium chloride, acrylamide, and N,N-dimethylacrylamide as polymerizing monomers; the mass ratio of methacryloyloxyethyltrimethylammonium chloride, acrylamide, N,N-dimethylacrylamide, and chitosan was 1:3:1:1.

[0031] The oligomeric quaternary ammonium salts are prepared from tetramethylethylenediamine and ethylene dibromide, with a molar ratio of 1:2 between the two.

[0032] The crosslinking agent is N,N-dimethylethylacrylamide ammonium chloride; the initiator is cumene hydroperoxide; the inorganic salt is sodium sulfate; and the regulator is n-butanethiol.

[0033] A method for preparing an anti-swelling and anti-shrinkage agent for oilfield water injection includes the following steps: (1) Mix polyetheramine, organic-inorganic composite agent, initiator, crosslinking agent and water, and react after mixing evenly; the reaction temperature is 60℃.

[0034] (2) Mix the oligomerized quaternary ammonium salt, inorganic salt, regulator and the reaction stream obtained in step (1) at a mixing temperature of 70°C and a reaction time of 4 hours to obtain an anti-swelling agent for oilfield water injection.

[0035] Example 3 An anti-swelling and anti-shrinkage agent for oilfield water injection is prepared from the following raw materials: 10 parts of oligomeric quaternary ammonium salt, 20 parts of polyetheramine, 10 parts of organic-inorganic composite agent, 3 parts of crosslinking agent, 1 part of initiator, 10 parts of inorganic salt, 0.25 parts of regulator, and 400 parts of water.

[0036] The organic-inorganic composite agent includes chitosan-modified cationic emulsion polymer and potassium chloride, with a mass ratio of chitosan-modified cationic emulsion polymer to potassium chloride of 3:1.

[0037] The chitosan-modified cationic emulsion polymer was prepared by introducing chitosan as a polymerizing monomer, using methacryloyloxyethyltrimethylammonium chloride, acrylamide, and N,N-dimethylacrylamide as polymerizing monomers; the mass ratio of methacryloyloxyethyltrimethylammonium chloride, acrylamide, N,N-dimethylacrylamide, and chitosan was 1:3:2:3.

[0038] The oligomeric quaternary ammonium salts are prepared from tetramethylethylenediamine and ethylene dibromide, with a molar ratio of 1:3 between the two.

[0039] The crosslinking agent is N,N-dimethylethylacrylamide ammonium chloride; the initiator is cumene hydroperoxide; the inorganic salt is sodium sulfate; and the regulator is n-butanethiol.

[0040] A method for preparing an anti-swelling and anti-shrinkage agent for oilfield water injection includes the following steps: (1) Mix polyetheramine, organic-inorganic composite agent, initiator, crosslinking agent and water, and react after mixing evenly; the reaction temperature is 80℃.

[0041] (2) Mix the oligomerized quaternary ammonium salt, inorganic salt, regulator and the reaction stream obtained in step (1) at a mixing temperature of 80°C and a reaction time of 1 to 5 hours to obtain an anti-swelling agent for oilfield water injection.

[0042] Comparative Example 1 The difference from Example 1 is that no organic-inorganic composite agent was added.

[0043] Comparative Example 2 The difference from Example 1 is that no oligomeric quaternary ammonium salt was added.

[0044] Comparative Example 3 The difference from Example 1 is that polyetheramine was not added.

[0045] Performance testing: The anti-swelling and shrinkage rates of the oilfield water injection anti-swelling and shrinkage agents prepared in Examples 1-3 and Comparative Examples 1-3 at different temperatures were evaluated and tested. The test results are shown in Table 1.

[0046] Swelling prevention rate: 0.50g of sodium bentonite and 10mL of 5wt% oilfield injection anti-swelling agent aqueous solution were added to a reaction vessel, mixed evenly, and then placed in an oven at different temperatures (60℃, 90℃) for 4h. After cooling to room temperature (25℃), the mixture was transferred to centrifuge tubes and centrifuged at 1500r / min for 15min. The volume of the treated sodium bentonite was measured as V1. A control experiment was conducted under the same conditions, in which 10mL of oilfield injection anti-swelling agent aqueous solution was replaced with deionized water, and the volume of sodium bentonite obtained by centrifugation was V0. The formula for calculating the swelling prevention rate is as follows: (V0 - V1) / V0 * 100%.

[0047] Swelling-shrinkage rate: 0.50g sodium bentonite and 7.5mL water were added to a centrifuge tube, mixed evenly, and allowed to stand for 4h. Then, 2.5mL of a 20wt% oilfield injection water anti-swelling and shrinkage agent was added to the centrifuge tube, mixed evenly, and transferred to a reaction vessel. The mixture was then placed in an oven and allowed to stand for 4h at different temperatures (60℃, 90℃). After cooling to room temperature (25℃), the mixture was transferred to a centrifuge tube and centrifuged at 1500r / min for 15min. The volume of the treated sodium bentonite was measured as V1. A control experiment was conducted under the same conditions. The 2.5mL oilfield injection water anti-swelling and shrinkage agent was replaced with deionized water, and the volume of the sodium bentonite obtained by centrifugation was V0. The formula for calculating the swelling-shrinkage rate is as follows: (V0 - V1) / V0 * 100%.

[0048] Table 1 Test Results The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An anti-swelling and anti-shrinkage agent for water injection in oil fields, characterized in that, It is prepared from the following raw materials: 5-10 parts of oligomeric quaternary ammonium salt, 5-20 parts of polyetheramine, 1-10 parts of organic-inorganic composite agent, 0.5-3 parts of crosslinking agent, 0.05-1 part of initiator, 1-10 parts of inorganic salt, 0.05-0.25 parts of regulator, and 50-400 parts of water.

2. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The organic-inorganic composite agent comprises chitosan-modified cationic emulsion polymer and potassium chloride, wherein the mass ratio of chitosan-modified cationic emulsion polymer to potassium chloride is 1 to 3:

1.

3. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 2, characterized in that, The chitosan-modified cationic emulsion polymer is prepared by introducing chitosan as a polymerizing monomer, using methacryloyloxyethyltrimethylammonium chloride, acrylamide, and N,N-dimethylacrylamide as polymerizing monomers. The mass ratio of methacryloyloxyethyltrimethylammonium chloride, acrylamide, N,N-dimethylacrylamide, and chitosan is 1:2-3:1-2:1-3.

4. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The oligomeric quaternary ammonium salt is prepared from tetramethylethylenediamine and ethylene dibromide, wherein the molar ratio of tetramethylethylenediamine to ethylene dibromide is 1:2 to 3.

5. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The crosslinking agent is one or more of N,N-dimethylethylacrylamide ammonium chloride, 2-alkyl-4-vinylbenzenesulfonate sodium copolymer, ethylene glycol diallyl ether, propylene glycol diallyl ether, and butanediol diallyl ether.

6. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The initiator is one or more of the following: cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, dodecyl peroxide, azobisisobutyronitrile, potassium persulfate, sodium persulfate, potassium persulfate-potassium bisulfite, and ammonium persulfate.

7. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The inorganic salt is one or more of sodium sulfate, sodium chloride, potassium chloride, magnesium chloride, magnesium sulfate, and ammonium chloride.

8. The anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 1, characterized in that, The regulator is one or more of n-butanethiol, tert-butanethiol, sodium hypophosphite, and carbon tetrabromide.

9. The method for preparing the anti-swelling and anti-shrinkage agent for oilfield water injection according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Mix polyetheramine, organic-inorganic composite agent, initiator, crosslinking agent and water, and carry out the reaction after mixing evenly; (2) Mix the oligomerized quaternary ammonium salt, inorganic salt, regulator and the reaction stream obtained in step (1) at a mixing temperature of 30-80℃ and a reaction time of 1-5h to obtain an anti-swelling agent for oilfield water injection.

10. The preparation method of the anti-swelling and anti-shrinkage agent for oilfield water injection according to claim 9, characterized in that, In step (1), the mixing reaction temperature is 40-80℃.

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