An adaptive particle gel profile control water plugging agent, a preparation method and application thereof

Abstract

The application belongs to the technical field of oil and gas field development, and particularly relates to a self-adaptive particle gel profile control water plugging agent and a preparation method and application thereof. The profile control water plugging agent comprises the following raw materials in parts by weight: skeleton monomer 15-25 parts, DMC 5-10 parts, cross-linking healing agent 4-10 parts, surfactant 0.5 part, potassium persulfate 0.1 part and sodium bisulfite 0.1 part. A hybrid micelle is constructed by using an amphiphilic component, a microgel system with macroscopic fluidity and microscopic suspended particle state is prepared through in-situ polymerization, a responsive dynamic network is constructed by relying on hydrophobic association and dynamic disulfide bond cooperation, deep shear resistance, movable and repeated gel sealing in the formation are realized, the water absorption profile of a heterogeneous reservoir can be significantly adjusted, the swept volume of water flooding is expanded, and the recovery rate is improved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to an adaptive particulate gel profile control and water shut-off agent, its preparation method, and its application. Background Technology

[0002] During water injection development in oilfields, due to the long-term scouring by injected water and the natural heterogeneity of the formation, high-permeability large water channels, large pore throats, or secondary fractures easily form within the formation. After entering the formation, the injected water often circulates ineffectively or inefficiently along these dominant channels, leading to premature water bursts in oil wells and a sharp increase in overall water cut. Meanwhile, a large amount of crude oil in medium- and low-permeability layers cannot be effectively displaced, severely restricting the ultimate recovery rate of the oilfield. In oilfield production enhancement and water control measures, water shut-off is a direct technical means, while adjusting the formation's water absorption profile (profile modification) is the ultimate goal of production enhancement. Currently, the commonly used profile modification and water shut-off agents in oilfields are mainly cross-linked gel particles. However, traditional in-situ cross-linked bulk gels, during surface preparation and pumping, are easily subjected to strong high-shear forces because they flow through narrow, high-velocity areas such as near-wellbore zones and perforations. This causes large-scale breakage of the covalent bonds within the gel molecular skeleton (i.e., shear degradation). Once degraded, they completely lose their sealing ability and cannot migrate to deeper formations to perform a sealing function. While conventional pre-crosslinked gel particles have high hardness, their fixed size lacks the "adaptability" to complex formation pore throats and they also lack self-repairing ability after being crushed under high pressure. In addition, many high-yield, high-water-cut oil reservoirs are accompanied by harsh formation water environments with high salinity, high salinity, and high calcium and magnesium ion content. When facing high-salt environments, traditional polyacrylamide-based water-blocking agents will experience severe molecular chain coiling and dehydration shrinkage due to the ion shielding effect, resulting in a sharp decrease in blocking strength and making it difficult to effectively fine-tune the permeability within high-permeability layers.

[0003] Therefore, developing a highly adaptable profile control and water shut-off agent that possesses good pump flowability on a macroscopic level, a granular structure on a microscopic level, deep shear resistance and self-healing properties, and the ability to control the gelation reaction state of adaptive particulate gel by changing the environmental salinity, thereby thickening and expanding the adaptive gel particles, and exhibiting strong rock adsorption selectivity, is a technical bottleneck that urgently needs to be solved in the field of oilfield chemistry. Summary of the Invention

[0004] To address the above issues, this invention provides an adaptive particulate gel profile control and water shut-off agent, its preparation method, and its application. Using a hybrid micelle constructed from surfactants and functional monomers as a soft template, in-situ free radical polymerization embeds zwitterionic monomers with anti-polyelectrolyte effects and self-healing materials with a physical-chemical dual dynamic crosslinking network into the polymer backbone. The aim is to develop a smart water shut-off agent with good flowability and deep shear resistance self-repair function, ultimately achieving efficient oilfield production enhancement.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides an adaptive particulate gel profile control and water-blocking agent, which comprises the following raw materials in parts by weight: 15-25 parts of skeleton monomer, 5-10 parts of DMC (methacryloyloxyethyltrimethylammonium chloride), 4-10 parts of crosslinking healing agent, 0.5 parts of surfactant, 0.1 parts of potassium persulfate, and 0.1 parts of sodium bisulfite.

[0006] Furthermore, the skeletal monomer is selected from any one of AM (acrylamide), MAM (methacrylamide), and DMAA (N,N'-dimethylacrylamide).

[0007] Furthermore, the surfactant is selected from APG (alkyl glycoside) or SDBS (sodium dodecylbenzene sulfonate).

[0008] Further, the crosslinking healing agent comprises the following raw materials: SBMA (3-(N,N-dimethyl-(2-(2-methylprop-2-enoyloxy)ethyl)ammonium)propane-1-sulfonic acid inner salt), C16-DMAAC (hexadecyl dimethyl allyl ammonium chloride), and BAC (N,N'-bis(acryloyl)cysteine), wherein the mass ratio of SBMA, C16-DMAAC, and BAC is 75:23:2.

[0009] Furthermore, the preparation method of the cross-linking healing agent is as follows: S1: Add C16-DMAAC to purified water and stir to dissolve it in order to construct a hydrophobic micelle system and obtain a micelle solution; S2: Pre-dissolve BAC in methanol to obtain a BAC solution, and then slowly add it dropwise to the micelle solution so that BAC is encapsulated in the hydrophobic cavity inside the micelles formed by C16-DMAAC, constructing dynamic cross-linked microdomains. Heat and stir to evaporate methanol to obtain a pre-cross-linked solution. S3: Add SBMA to the pre-crosslinking solution and stir until completely dissolved to obtain the crosslinking healing agent.

[0010] This invention also provides a method for preparing an adaptive particulate gel profile control and water-blocking agent, the specific steps of which are as follows: Step 1: After dissolving the surfactant, add the backbone monomer and DMC to it, and stir until completely dissolved to obtain the initial solution; Step 2: While stirring, slowly add the crosslinking healing agent dropwise to the initial solution. The micelles formed by the crosslinking healing agent micelle layer and the surfactant in the initial solution will interlock under the hydrophilic-hydrophobic interaction, forming a more stable hybrid micelle. The hydrophobic BAC will continue to remain in the hydrophobic cavity of the hybrid micelle, while the hydrophilic and amphiphilic molecules are exposed to the aqueous phase or bind to the hydrophilic head of the hybrid micelle, resulting in a mixed solution. Step 3: Adjust the pH of the mixture to neutral, deoxygenate under a nitrogen atmosphere for 10 min, then add potassium persulfate and sodium bisulfite, stir to dissolve. Potassium persulfate and sodium bisulfite act as crosslinking initiators to promote in-situ polymerization of the backbone monomers in the micelle state, preventing excessive crosslinking, which would result in high gel consistency and poor flowability, forming a uniformly distributed microgel. This retains the gel properties for water plugging, while also having considerable flowability to penetrate deep into cracks or pore throats. After a 4-hour heat treatment, the mixture is cured and discharged, then dried and pulverized to obtain an adaptive particulate gel profile control and water plugging agent.

[0011] The present invention also provides an application of an adaptive particulate gel profile control and water shut-off agent, which is used in the field of oil and gas field development.

[0012] Furthermore, the profile control and water shut-off agent is used for selective water shut-off or crack filling during oil and gas field development.

[0013] Furthermore, the profile control and water shut-off agent is used for water control and profile control in formation water environments with high mineralization or high salinity and high calcium and magnesium content.

[0014] The beneficial effects achieved by this invention are as follows: The adaptive particulate gel profile control and water-blocking agent provided by this invention introduces a composite mechanism of in-situ polymerization of hybrid micelles and dynamic responsive self-healing. It utilizes the spontaneous association of the long-chain physical healing monomer C16-DMAAC in water to establish hydrophobic micelles. Through strong hydrophobic interactions, the poorly soluble chemical healing monomer BAC is firmly encapsulated within the hydrophobic cavity of the micelle core. During the overall formulation of the water-blocking agent, this cross-linked healing agent micelle layer and the surfactant micelles in the main framework system undergo deep molecular integration under hydrophilic-hydrophobic interactions, in-situ constructing a more stable and highly uniformly distributed hybrid micelle soft template. When an initiator is added, the redox system releases free radicals, forcing the framework monomers to undergo in-situ spatial localization polymerization under the microscopic state confined by the hybrid micelles. This unique confined molding mechanism results in a product that macroscopically resembles a viscous fluid similar to an aqueous solution of polyacrylamide (with extremely low pumping resistance and significant shear thinning behavior), while under a high-magnification microscope, it appears as liquid-suspended, uniformly sized microgel particles. The long carbon chains of C16-DMAAC form strongly hydrophobic association microdomains in the aqueous phase, serving as reversible physical cross-linking points. BAC introduces dynamically reversible covalent disulfide bonds. When the profile control and water shut-off agent passes through the near-wellbore high-shear zone, the physical hydrophobic bonds dissociate and the disulfide bonds undergo reversible breakage, allowing the gel particles to "break down" and pass through with low viscosity. When it migrates to the deeper formation and the flow rate slows down, the hydrophobic long chains spontaneously reassociate and aggregate, while the disulfide bonds dynamically cross-link, causing the microgels to re-aggregate into micelles (i.e., self-healing), thus achieving deep plugging.

[0015] The profile control and water shut-off agent provided in this application has the functions of environmental responsiveness, deep sealing, selective water control, and no damage to the oil-producing layer. It is also stable under high temperature and high salinity conditions and meets the clean production specifications of modern green oilfield development. Attached Figure Description

[0016] Figure 1 The contact angle test results are for the profile control and water shut-off agents prepared in Example 5 and Comparative Example 1; Figure 2 The swelling performance of the profile control and water-blocking agents prepared in Examples 2-5 and Comparative Example 1 is investigated. Figure 3 The results of the swelling performance study of the profile control and water shut-off agent prepared in Example 5 in water with different salinities; Figure 4 The degradation rate of the profile control and water-blocking agents prepared in Example 5 and Comparative Example 1 are as follows; Figure 5 The results of the plugging rate investigation of the profile control and water plugging agents prepared in Example 5 and Comparative Example 2 are shown. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0019] Unless otherwise specified, all methods used in the following embodiments are conventional. Unless otherwise specified, all materials used in the following embodiments are new materials purchased from the market. The CAS number of AM used in the following embodiments and comparative examples is 79-06-1. All raw materials used are industrial grade.

[0020] Example 1: This example provides a cross-linking healing agent and its preparation method. The cross-linking healing agent comprises the following raw materials in parts by weight: 15 parts SBMA, 4.6 parts C16-DMAAC, and 0.4 parts BAC; The preparation method of the cross-linking healing agent is as follows: S1: Take 4.6 parts of C16-DMAAC and add it to 50 parts of purified water and stir to dissolve to obtain a micelle solution; S2: Dissolve 0.4 parts of BAC in 2 parts of methanol to obtain a BAC solution, and then slowly add it dropwise to the micelle solution at a rate of 1 mL / min. Heat and stir at 60℃ and 300 rpm to evaporate the methanol and obtain a pre-crosslinked solution. S3: Add 15 parts of SBMA to the pre-crosslinking solution and stir at 300 rpm for 20 min until completely dissolved to obtain the crosslinking healing agent.

[0021] In the following examples, all cross-linking healing agents used were prepared using the raw material method of this example.

[0022] Example 2: This example provides an adaptive particulate gel profile control and water-stopping agent, which comprises the following raw materials in parts by weight: AM 15 parts, DMC 10 parts, crosslinking healing agent 10 parts, APG 0.5 parts, potassium persulfate 0.1 parts, and sodium bisulfite 0.1 parts; This embodiment also provides a method for preparing an adaptive particulate gel profile control and water-blocking agent, the specific steps of which are as follows: Step 1: Dissolve 0.5 parts of APG in 100 parts of purified water, then add 15 parts of AM and 5 parts of DMC, and stir at 150 rpm until completely dissolved to obtain the initial solution; Step 2: Add 5 parts of cross-linking healing agent slowly dropwise to the initial solution while stirring at a speed of 200 rpm and a dropping rate of 2 mL / min. After the addition is complete, continue stirring and mixing for 15 min to obtain the mixture. Step 3: Adjust the pH of the mixture to neutral using a 5% sodium hydroxide solution, deoxygenate under a nitrogen atmosphere for 10 min, then add 0.1 parts potassium persulfate and 0.1 parts sodium bisulfite, stir at 200 rpm to dissolve, keep at 30℃ for 4 h, let stand for 12 h to mature, and then discharge. After drying and pulverizing at 75℃, the adaptive particulate gel profile control and water-blocking agent is obtained.

[0023] Example 3: This example provides an adaptive particulate gel profile control and water-blocking agent, which comprises the following raw materials in parts by weight: 20 parts MAM, 8 parts DMC, 7 parts crosslinking healing agent, 0.5 parts APG, 0.1 parts potassium persulfate, and 0.1 parts sodium bisulfite; This embodiment also provides a method for preparing an adaptive particulate gel profile control and water-blocking agent, the specific steps of which are as follows: Step 1: Dissolve 0.5 parts of APG in 100 parts of purified water, then add 20 parts of MAM and 8 parts of DMC, and stir at 150 rpm until completely dissolved to obtain the initial solution; Step 2: Add 7 parts of cross-linking healing agent slowly dropwise to the initial solution while stirring. The stirring speed is 200 rpm and the dropping rate is 2 mL / min. After the addition is complete, continue stirring and mixing for 15 min to obtain the mixture. Step 3: Adjust the pH of the mixture to neutral using a 5% sodium hydroxide solution, deoxygenate under a nitrogen atmosphere for 10 min, then add 0.1 parts potassium persulfate and 0.1 parts sodium bisulfite, stir at 200 rpm to dissolve, keep at 30℃ for 4 h, let stand for 12 h to mature, and then discharge. After drying and pulverizing at 75℃, the adaptive particulate gel profile control and water-blocking agent is obtained.

[0024] Example 4: This example provides an adaptive particulate gel profile control and water-blocking agent, which comprises the following raw materials in parts by weight: 25 parts DMAA, 5 parts DMC, 5 parts crosslinking healing agent, 0.5 parts SDBS, 0.1 parts potassium persulfate, and 0.1 parts sodium bisulfite; This embodiment also provides a method for preparing an adaptive particulate gel profile control and water-blocking agent, the specific steps of which are as follows: Step 1: Dissolve 0.5 parts of SDBS in 100 parts of purified water, then add 25 parts of DMAA and 5 parts of DMC, and stir at 150 rpm until completely dissolved to obtain the initial solution; Step 2: Add 5 parts of cross-linking healing agent slowly dropwise to the initial solution while stirring at a speed of 200 rpm and a dropping rate of 2 mL / min. After the addition is complete, continue stirring and mixing for 15 min to obtain the mixture. Step 3: Adjust the pH of the mixture to neutral using a 5% sodium hydroxide solution, deoxygenate under a nitrogen atmosphere for 10 min, then add 0.1 parts potassium persulfate and 0.1 parts sodium bisulfite, stir at 200 rpm to dissolve, keep at 30℃ for 4 h, let stand for 12 h to mature, and then discharge. After drying and pulverizing at 75℃, the adaptive particulate gel profile control and water-blocking agent is obtained.

[0025] Example 5: This example provides an adaptive particulate gel profile control and water-stopping agent, which comprises the following raw materials in parts by weight: AM 21 parts, DMC 10 parts, crosslinking healing agent 4 parts, SDBS 0.5 parts, potassium persulfate 0.1 parts, and sodium bisulfite 0.1 parts; This embodiment also provides a method for preparing an adaptive particulate gel profile control and water-blocking agent, the specific steps of which are as follows: Step 1: Dissolve 0.5 parts of SDBS in 100 parts of purified water, then add 21 parts of AM and 10 parts of DMC, and stir at 150 rpm until completely dissolved to obtain the initial solution; Step 2: Add 4 parts of cross-linking healing agent slowly dropwise to the initial solution while stirring. The stirring speed is 200 rpm and the dropping rate is 2 mL / min. After the addition is complete, continue stirring and mixing for 15 min to obtain the mixture. Step 3: Adjust the pH of the mixture to neutral using a 5% sodium hydroxide solution, deoxygenate under a nitrogen atmosphere for 10 min, then add 0.1 parts potassium persulfate and 0.1 parts sodium bisulfite, stir at 200 rpm to dissolve, keep at 30℃ for 4 h, let stand for 12 h to mature, and then discharge. After drying and pulverizing at 75℃, the adaptive particulate gel profile control and water-blocking agent is obtained.

[0026] Comparative Example 1: The difference from Example 5 is that no cross-linking healing agent was added; the rest is the same as Example 5.

[0027] Comparative Example 2: A commercially available polyacrylamide water-blocking agent.

[0028] Contact angle assessment: The profile control and water-blocking agents prepared in Example 5 and Comparative Example 1 were pressed into sheet-like solids, and the contact angles of the samples were measured using a DSA25 contact angle meter. The results are shown in the figure. Figure 1 .

[0029] Water absorption performance test: 0.5 g of the profile control and water-blocking agents prepared in Examples 2-5 and Comparative Example 1 were weighed and dissolved in water with a mineralization of 20 g / L to swell. The mass of the gel particles was recorded at 0, 10, 30, 60, 120, and 240 min. The results are shown in the figure. Figure 2 The swelling results of the profile control and water shut-off agent prepared in Example 5 in water with mineralization of 0, 2000, and 40 g / L were simultaneously investigated. The results are shown in [Figure 1]. Figure 3 .

[0030] Degradation performance evaluation: 0.5 g of the profile control and water-blocking agent prepared in Example 5 and Comparative Example 1 was weighed and fully swollen in water with a mineralization of 20 g / L. The solution was then dried in an oven at 80℃, and the aging mass W1 was recorded. The degradation rate % was calculated as (W1 - 0.5) / 0.5 × 100%. The results are shown in [Figure number missing]. Figure 4 .

[0031] Performance evaluation of plugging: 20 g each of the profile control and plugging agent prepared in Example 5 and the commercially available polyacrylamide plugging agent from Comparative Example 2 were weighed and placed in 1000 mL of water with a mineralization of 20 g / L. The mixture was stirred to disperse and swell, yielding a swollen solution. Quartz sand of 80-100 mesh was then packed into a sand-filling pipe to simulate underground rock formations. The water phase permeability before and after the swollen solution was injected into the sand-filling pipe for plugging was tested. The results are shown in [Figure number missing]. Figure 5 .

[0032] Figure 1The results showed that the profile control and water-blocking agent prepared in Example 5 had stronger hydrophilicity, and its contact angle decreased from 76.4° to 58.5° compared with Comparative Example 1.

[0033] Figure 2 The results showed that the profile control and water-blocking agents prepared in Examples 2-5 had a stable water absorption ratio of 22-27 times, which was significantly improved compared with the water-blocking agent in Comparative Example 1. This indicates that the crosslinking healing agent has a strong ability to regulate the hybrid micelles and the polymerization and swelling behavior of polymer monomers.

[0034] Figure 3 The results showed that, under a high-salt environment of 40 g / L, the profile control and water shut-off agent prepared in Example 5 still had about 24 times the water absorption capacity, demonstrating insensitivity to salt, which is beneficial for its application in high-salt and high-mineralization reservoirs.

[0035] Figure 4 The results showed that, due to its micropolymerization behavior, the hybrid micelle structure of Example 5 could effectively inhibit degradation during the secondary and tertiary water absorption processes, and thus had the ability to be reused for a long time.

[0036] Figure 5 The results showed that Example 5 had a higher sealing rate and more complete sealing than conventional polyacrylamide plugging agent, indicating that it could penetrate into small and deep pore throat areas and had good fluidity.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0038] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. An adaptive particulate gel profile control and water-blocking agent, characterized in that, The profile control and water-blocking agent comprises the following raw materials in parts by weight: 15-25 parts of skeleton monomer, 5-10 parts of DMC, 4-10 parts of crosslinking healing agent, 0.5 parts of surfactant, 0.1 parts of potassium persulfate and 0.1 parts of sodium bisulfite; The cross-linking healing agent comprises the following raw materials: SBMA, C16-DMAAC, and BAC; The preparation method of the cross-linking healing agent is as follows: S1: Dissolve C16-DMAAC to obtain a micelle solution; S2: After pre-dissolving BAC, add it dropwise to the micelle solution, heat and stir to obtain a pre-crosslinked solution; S3: Add SBMA to the pre-crosslinking solution to dissolve it, and obtain the crosslinking healing agent.

2. The adaptive particulate gel profile control and water-blocking agent according to claim 1, characterized in that, The mass ratio of SBMA, C16-DMAAC, and BAC is 75:23:

2.

3. The adaptive particulate gel profile control and water-blocking agent according to claim 1, characterized in that, The skeleton monomer is selected from any one of AM, MAM and DMAA.

4. The adaptive particulate gel profile control and water-blocking agent according to claim 3, characterized in that, The surfactant is selected from APG or SDBS.

5. A method for preparing an adaptive particulate gel profile control and water-blocking agent according to any one of claims 1-4, characterized in that, The specific steps are as follows: Step 1: After dissolving the surfactant, add the backbone monomer and DMC to it and dissolve to obtain the initial solution; Step 2: While stirring, slowly add the cross-linking healing agent dropwise to the initial solution to obtain a mixture; Step 3: Adjust the pH of the mixture and remove oxygen, then add potassium persulfate and sodium bisulfite to dissolve, react, mature, dry and pulverize to obtain an adaptive particulate gel profile control and water-blocking agent.

6. The preparation method of the adaptive particulate gel profile control and water-blocking agent according to claim 5, characterized in that, In step 3, the process of adjusting the pH of the mixture is to adjust the pH of the mixture to neutral.

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