Anti-collapse plugging agent as well as preparation and application thereof
By using anti-collapse sealing agents prepared by materials such as polystyrene-acrylamide copolymers, the problem of difficult sealing of micro-cracks and micropores of mud shale formations is solved, and efficient well wall stability and reservoir protection are achieved.
Patent Information
- Application Number
- CN202311674258.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-07
- Publication Date
- 2025-06-10
AI Technical Summary
During drilling and reservoirs, micro-cracks and micropores of mud shale formations are difficult to effectively seal, resulting in instability of the well wall and damage to the reservoir.
An anti-collapse sealing agent is used, which consists of polystyrene-acrylamide copolymer, emulsifier SP-80, white oil and silica powder, and is prepared by polymerization and has high temperature resistance.
The anti-collapse sealing agent can quickly form a sealing layer under high temperature conditions, significantly improve the sealing performance of drilling fluid, reduce the risk of well wall instability, and reduce reservoir damage.
Smart Images
Figure BDA0004594288280000041 
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Abstract
Description
Technical Field
[0001] The present invention relates to an anti-collapse plugging agent and its preparation and application. Background Art
[0002] More than 90% of wellbore instabilities occur in shale formations, mainly hard and brittle shale. When the initially generated microcracks cannot be plugged in time, pressure transmission causes the microcracks to expand, resulting in a deterioration of formation strength. If the filtrate of the drilling fluid enters the formation through seepage under the drilling pressure difference, it will hydrate the shale, causing uneven stress on the formation rock and leading to wellbore instability and easy collapse. Therefore, for such formations, it is necessary to enhance the plugging performance of the drilling fluid. At the same time, during the drilling of the reservoir, once the oil and gas layer is drilled, the reservoir loses its original balance state, and the external fluid that does not match the reservoir fluid is extremely likely to damage the reservoir. The key to reservoir protection also lies in strengthening the plugging of microcracks and micropores. Summary of the Invention
[0003] In order to further improve the temperature resistance and physical plugging performance of the plugging agent product and further enrich the selection space of the plugging agent product, the present invention is made.
[0004] As an aspect of the present invention, it relates to an anti-collapse plugging agent, which comprises a polystyrene-acrylamide copolymer, emulsifier SP-80, white oil, and silica powder. The particle size of the silica powder is 0.02um - 0.1um. This anti-collapse plugging agent has the characteristic of high temperature resistance, can effectively play the role of anti-collapse plugging, and is beneficial to reducing the incidence of wellbore instability problems and reducing reservoir damage.
[0005] As another aspect of the present invention, it relates to a method for preparing the above anti-collapse plugging agent, including:
[0006] (1) Dissolve styrene and acrylamide in water, add n-butanol, and add an initiator for polymerization reaction under the condition of pH value 8 - 9;
[0007] (2) Add an emulsifier and white oil and stir evenly;
[0008] (3) Add a dispersant and stir evenly.
[0009] In specific embodiments, the initiator is potassium persulfate or ammonium persulfate; the emulsifier is emulsifier SP-80 or OP-10; the dispersant is silica powder or calcium carbonate powder.
[0010] In specific embodiments, the reaction materials are added according to the following mass parts: 15 - 25 parts of styrene, 10 - 20 parts of acrylamide, 10 - 20 parts of n-butanol, 2 - 5 parts of emulsifier, 0.3 - 0.5 parts of initiator, 30 - 50 parts of white oil, and 1 - 4 parts of dispersant.
[0011] In specific embodiments, the polymerization reaction is carried out under the conditions of 40°C - 60°C, preferably under the conditions of 50°C - 60°C.
[0012] As another aspect of the present invention, it relates to a drilling fluid containing the above anti-collapse plugging agent.
[0013] As yet another aspect of the present invention, it relates to the application of the anti-collapse plugging agent in oil well plugging.
[0014] The anti-collapse plugging agent provided by the present invention has a temperature resistance performance up to 150°C, has a good match with the fracture development of hard and brittle shale, and can quickly form a rapid plugging layer around the wellbore near the well wall to achieve the purpose of broad-spectrum plugging.
[0015] The anti-collapse plugging agent provided by the present invention has low requirements for the pore size distribution law of the reservoir and has broad-spectrum properties.
[0016] The anti-collapse plugging agent provided by the present invention is mainly concentrated in the near-well zone and has little impact on the later reservoir stimulation work. Detailed implementation mode
[0017] The following examples are listed to specifically describe the present invention. It should be noted that the following examples are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made to the present invention still fall within the protection scope of the present invention. The parts mentioned below are parts by mass.
[0018] Example 1 (formulation example)
[0019] Dissolve 20 g of styrene and 15 g of acrylamide in 200 g of water and stir evenly, then add 15 g of n-butanol. Adjust the pH value to 9, add 0.5 g of ammonium persulfate as an initiator, react at 50°C for 4 h, cool, then add 3 g of emulsifier SP-80 and 40 g of white oil and stir evenly, and finally add 3 g of silicon dioxide powder with a particle size of 0.02 um - 0.1 um and stir evenly. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing polystyrene-acrylamide copolymer, emulsifier SP-80, white oil and silicon dioxide powder.
[0020] Example 2 (formulation example)
[0021] Dissolve 15 g of styrene and 15 g of acrylamide in 150 g of aqueous solution and stir well in a reaction kettle. Then add 10 g of n-butanol. Adjust the pH value to 8, add 0.3 g of potassium persulfate as an initiator, react at 60 °C for 3 h, cool, then add 2 g of emulsifier OP-10 and 30 g of white oil and stir well. Finally, add 2 g of calcium carbonate powder with a particle size of 0.02 μm to 0.1 μm and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing a polystyrene-acrylamide copolymer, emulsifier OP-10, white oil, and calcium carbonate powder.
[0022] Example 3 (formulation example)
[0023] Dissolve 25 g of styrene and 20 g of acrylamide in 200 g of aqueous solution and stir well in a reaction kettle. Then add 20 g of n-butanol. Adjust the pH value to 9, add 0.5 g of ammonium persulfate as an initiator, heat the reaction kettle to 50 °C, react for 3 h, cool, then add 4 g of emulsifier SP-80 and 50 g of white oil and stir well. Finally, add 4 g of silica powder with a particle size of 0.02 μm to 0.1 μm and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing a polystyrene-acrylamide copolymer, emulsifier SP-80, white oil, and silica powder.
[0024] Example 4 (formulation example)
[0025] Dissolve 15 g of styrene and 10 g of acrylamide in 100 g of aqueous solution and stir well in a reaction kettle. Then add 10 g of n-butanol. Adjust the pH value to 8, add 0.3 g of potassium persulfate as an initiator, heat the reaction kettle to 60 °C, react for 3 h, cool, then add 2 g of emulsifier OP-10 and 30 g of white oil and stir well. Finally, add 1 g of silica powder with a particle size of 0.02 μm to 0.1 μm and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing a polystyrene-acrylamide copolymer, emulsifier OP-10, white oil, and silica powder.
[0026] Example 5 (formulation example)
[0027] Dissolve 20 g of styrene and 15 g of acrylamide in 200 g of aqueous solution, stir well in a reaction kettle, and then add 15 g of n-butanol. Adjust the pH value to 10, add 0.5 g of ammonium persulfate as an initiator, heat the reaction kettle to 40 °C, after reacting for 4 h, cool it, then add 5 g of emulsifier OP-10 and 50 g of white oil and stir well, and finally add 4 g of silica powder with a particle size of 0.02 um - 0.1 um and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing polystyrene-acrylamide copolymer, emulsifier OP-10, white oil and silica powder.
[0028] Comparative Example 1 (formulation example)
[0029] Dissolve 6 g of styrene and 3 g of acrylamide in 60 g of aqueous solution, stir well in a reaction kettle, and then add 5 g of n-butanol. Adjust the pH value to 7, add 0.1 g of ammonium persulfate as an initiator, heat the reaction kettle to 40 °C, after reacting for 5 h, cool it, then add 1 g of emulsifier SP-80 and 10 g of white oil and stir well, and finally add 0.3 g of silica powder with a particle size of 0.02 um - 0.1 um and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing polystyrene-acrylamide copolymer, emulsifier SP-80, white oil and silica powder.
[0030] Comparative Example 2 (formulation example)
[0031] Dissolve 30 g of styrene and 25 g of acrylamide in 300 g of aqueous solution, stir well in a reaction kettle, and then add 25 g of n-butanol. Adjust the pH value to 10, add 2.0 g of potassium persulfate as an initiator, heat the reaction kettle to 70 °C, after reacting for 2 h, cool it, then add 15 g of emulsifier OP-10 and 70 g of white oil and stir well, and finally add 8.0 g of calcium carbonate powder with a particle size of 0.02 um - 0.1 um and stir well. The resulting liquid is the anti-collapse plugging agent. The obtained anti-collapse plugging agent is a composition containing polystyrene-acrylamide copolymer, emulsifier OP-10, white oil and calcium carbonate powder.
[0032] Performance Evaluation 1: The anti-collapse plugging agent used in this example is the product prepared in Example 1.
[0033] Compatibility of drilling fluid system: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid, divide it into three portions, each portion is 400 mL. Add 4 g of anti-collapse plugging agent to one portion, add 8 g of anti-collapse plugging agent to another portion, and conduct rheological property tests.
[0034] The test results are shown in Table 1 below.
[0035] Table 1:
[0036]
[0037] As can be seen from the test results in Table 1, after adding the anti-collapse plugging agent to the water-based drilling fluid, there is almost no impact on the rheological properties of the drilling fluid system, and it has good compatibility with the drilling fluid system.
[0038] Temperature resistance performance: Test the temperature resistance ability of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 portions of base slurry. For one portion, conduct rheological property and filtration loss reduction property tests at room temperature, and age the other portion. The aging conditions are 150°C × 16 h. After aging, conduct rheological property and filtration loss reduction property tests.
[0039] The test results are shown in Table 2 below.
[0040] Table 2:
[0041]
[0042] As can be seen from the test results in Table 2, after the anti-collapse plugging agent is aged at 150°C for 16 h, it has good rheological properties, appropriate viscosity and shear properties, and stable filtration loss reduction properties, indicating that this anti-collapse plugging agent can resist high temperatures of 150°C.
[0043] PPA plugging and filtration loss performance: Test the PPA plugging and filtration loss performance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to one portion of the base slurry. Use a PPA plugging and filtration loss instrument to conduct plugging and filtration loss performance tests at room temperature and a pressure difference of 3.5 MPa.
[0044] The test results are shown in Table 3 below.
[0045] Table 3:
[0046]
[0047] As can be seen from the test results in Table 3, when the dosage of this anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging and filtration loss reaches 73%, indicating that this anti-collapse plugging agent is beneficial to improving the plugging performance of the soil slurry and can significantly improve the plugging ability of the mud cake.
[0048] Performance evaluation 2: The anti-collapse plugging agent used in this example is the product prepared in Example 2.
[0049] Compatibility of drilling fluid systems: Test the influence of this product on the rheological properties of drilling fluid systems. The test method is as follows: Take common water-based drilling fluid, divide it into three portions, each portion being 400 mL. Add 4 g of anti-collapse plugging agent to one portion, and add 8 g of anti-collapse plugging agent to another portion, and conduct rheological property tests.
[0050] The test results are shown in Table 4 below.
[0051] Table 4:
[0052]
[0053] It can be seen from the test results in Table 4 that after adding the anti-collapse plugging agent to the water-based drilling fluid, there is almost no influence on the rheological properties of the drilling fluid, and it has good compatibility with the drilling fluid system.
[0054] High temperature resistance: Test the high temperature resistance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a closed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 portions of base slurry. Conduct rheological property and fluid loss reduction property tests on one portion at room temperature, and age the other portion. The aging condition is 150°C × 16 h, and conduct rheological property and fluid loss reduction property tests after aging.
[0055] The test results are shown in Table 5 below.
[0056] Table 5:
[0057]
[0058] It can be seen from the test results in Table 5 that after aging the anti-collapse plugging agent at 150°C for 16 h, it has good rheological properties, appropriate viscosity and shear properties, and stable fluid loss reduction properties, indicating that this anti-collapse plugging agent can resist high temperatures of 150°C.
[0059] PPA plugging and fluid loss performance: Test the PPA plugging and fluid loss performance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a closed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to one portion of the base slurry, and use a PPA plugging and fluid loss instrument to conduct plugging and fluid loss performance tests at room temperature and a pressure difference of 3.5 MPa.
[0060] The test results are shown in Table 6 below.
[0061] Table 6:
[0062]
[0063] As can be seen from the test results in Table 6, when the dosage of the anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging filtration loss reaches 70%, indicating that the anti-collapse plugging agent is beneficial to improving the plugging performance of the mud and can significantly improve the plugging ability of the mud cake.
[0064] Performance evaluation 3: The anti-collapse plugging agent used in this example is the product prepared in Example 3.
[0065] Compatibility with drilling fluid system: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid, divide it into three parts, 400 mL for each part. Add 4 g of anti-collapse plugging agent to one part, and add 8 g of anti-collapse plugging agent to another part, and then conduct rheological property tests.
[0066] The test results are shown in Table 7 below.
[0067] Table 7:
[0068]
[0069] As can be seen from the test results in Table 7, after adding the anti-collapse plugging agent to the water-based drilling fluid, it has almost no influence on the rheological properties of the drilling fluid and has good compatibility with the drilling fluid system.
[0070] High temperature resistance performance: Test the high temperature resistance ability of this product. The test method is as follows: Prepare 2 parts of 400 mL bentonite base slurry with a mass fraction of 5%. After curing these 2 parts of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 parts of base slurry. Conduct rheological property and filtration loss reduction property tests on one part at room temperature, and age the other part. The aging condition is 150°C × 16 h, and conduct rheological property and filtration loss reduction property tests after aging.
[0071] The test results are shown in Table 8 below.
[0072] Table 8:
[0073]
[0074] As can be seen from the test results in Table 8, after the anti-collapse plugging agent is aged at 150°C for 16 h, it has good rheological properties, appropriate viscosity and shear properties, and stable filtration loss reduction properties, indicating that the anti-collapse plugging agent can resist high temperature of 150°C.
[0075] PPA plugging filtration performance: Test the PPA plugging filtration performance of this product. The test method is as follows: Prepare 2 parts of 400 mL bentonite base slurry with a mass fraction of 5%. After curing these 2 parts of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to one part of the base slurry, and use a PPA plugging filtration instrument to conduct plugging filtration performance tests at room temperature and a pressure difference of 3.5 MPa.
[0076] The test results are shown in Table 9 below.
[0077] Table 9:
[0078]
[0079] As can be seen from the test results in Table 9, when the dosage of the sloughing prevention plugging agent is 2%, the reduction rate of the PPA plugging filtration loss reaches 72%, indicating that the sloughing prevention plugging agent is beneficial to improving the plugging performance of the mud and can significantly improve the plugging ability of the mud cake.
[0080] Performance evaluation 4: The sloughing prevention plugging agent used in this example is the product prepared in Example 4.
[0081] Compatibility with the drilling fluid system: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid, divide it into three parts, each part is 400 mL. Add 4 g of the sloughing prevention plugging agent to one part, and add 8 g of the sloughing prevention plugging agent to another part, and then conduct rheological property tests.
[0082] The test results are shown in Table 10 below.
[0083] Table 10:
[0084]
[0085] As can be seen from the test results in Table 10, after adding the sloughing prevention plugging agent to the water-based drilling fluid, it has little influence on the rheological properties of the drilling fluid and has good compatibility with the drilling fluid system.
[0086] Temperature resistance performance: Test the temperature resistance ability of this product. The test method is as follows: Prepare 2 parts of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 parts of base slurry in a closed container at 25°C ± 1°C for 24 h, add 8 g of the sloughing prevention plugging agent to each of the 2 parts of base slurry. Conduct rheological property and filtration loss reduction property tests on one part at room temperature, and age the other part. The aging condition is 150°C × 16 h, and conduct rheological property and filtration loss reduction property tests after aging.
[0087] The test results are shown in Table 11 below.
[0088] Table 11:
[0089]
[0090] As can be seen from the test results in Table 11, after the sloughing prevention plugging agent is aged at 150°C for 16 h, it has good rheological properties, appropriate viscosity and shear properties, and stable filtration loss reduction properties, indicating that the sloughing prevention plugging agent can resist high temperature of 150°C.
[0091] PPA Plugging Filtration Performance: Test the PPA plugging filtration performance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to one of the base slurries. Use the PPA plugging filtration instrument to conduct the plugging filtration performance test at room temperature and a pressure difference of 3.5 MPa.
[0092] The test results are shown in Table 12 below.
[0093] Table 12:
[0094]
[0095] From the test results in Table 12, it can be seen that when the dosage of the anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging filtration volume reaches 66%, indicating that this anti-collapse plugging agent is beneficial to improving the plugging performance of the soil slurry and can significantly improve the plugging ability of the mud cake.
[0096] Performance Evaluation 5: The anti-collapse plugging agent used in this example is the product prepared in Example 5.
[0097] Compatibility with Drilling Fluid System: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid and divide it into three portions, each portion being 400 mL. Add 4 g of anti-collapse plugging agent to one portion and 8 g of anti-collapse plugging agent to another portion, and conduct rheological property tests.
[0098] The test results are shown in Table 13 below.
[0099] Table 13:
[0100]
[0101] From the test results in Table 13, it can be seen that after adding the anti-collapse plugging agent to the water-based drilling fluid, it has little influence on the rheological properties of the drilling fluid and has good compatibility with the drilling fluid system.
[0102] High Temperature Resistance Performance: Test the high temperature resistance ability of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 portions of base slurry. Conduct rheological property and water loss reduction property tests on one portion at room temperature, and age the other portion. The aging condition is 150°C × 16 h, and conduct rheological property and water loss reduction property tests after aging.
[0103] The test results are shown in Table 14 below.
[0104] Table 14:
[0105]
[0106] As can be seen from the test results in Table 14, after the anti-collapse plugging agent is aged at 150 °C for 16 h, it has good rheological properties, appropriate viscosity and shear properties, and stable water loss reduction performance, indicating that the anti-collapse plugging agent can resist high temperature of 150 °C.
[0107] PPA plugging and filtration loss performance: Test the PPA plugging and filtration loss performance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite-based slurry with a mass fraction of 5%. After curing these 2 portions of slurry in a sealed container at 25 °C ± 1 °C for 24 h, add 8 g of anti-collapse plugging agent to one of the slurries, and use a PPA plugging and filtration loss instrument to conduct plugging and filtration loss performance tests at room temperature and a pressure difference of 3.5 MPa.
[0108] The test results are shown in Table 15 below.
[0109] Table 15:
[0110]
[0111] As can be seen from the test results in Table 15, when the addition amount of the anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging and filtration loss amount reaches 49%, indicating that the anti-collapse plugging agent has certain plugging performance.
[0112] Performance evaluation 6: The anti-collapse plugging agent used in this example is the product prepared in Comparative Example 1.
[0113] Compatibility with drilling fluid system: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid and divide it into three portions, each portion being 400 mL. Add 4 g of anti-collapse plugging agent to one portion and 8 g of anti-collapse plugging agent to another portion, and conduct rheological property tests.
[0114] The test results are shown in Table 16 below.
[0115] Table 16:
[0116]
[0117] As can be seen from the test results in Table 16, after adding the anti-collapse plugging agent to the water-based drilling fluid, the viscosity and initial and final shear of the drilling fluid system increase, and the compatibility with the drilling fluid system is poor.
[0118] High temperature resistance performance: Test the high temperature resistance ability of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite-based slurry with a mass fraction of 5%. After curing these 2 portions of slurry in a sealed container at 25 °C ± 1 °C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 portions of slurry. Conduct rheological property and water loss reduction performance tests on one portion at room temperature, and age the other portion. The aging conditions are 150 °C × 16 h, and conduct rheological property and water loss reduction performance tests after aging.
[0119] The test results are shown in Table 17 below.
[0120] Table 17:
[0121]
[0122] It can be seen from the test results in Table 17 that after the anti-collapse plugging agent is aged at 150 °C for 16 h, the viscosity and initial and final shear are small, and the fluid loss reduction increases, indicating that the anti-collapse plugging agent has poor temperature resistance.
[0123] PPA plugging and fluid loss performance: Test the PPA plugging and fluid loss performance of this product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a closed container at 25 °C ± 1 °C for 24 h, add 8 g of anti-collapse plugging agent to one portion of the base slurry, and use a PPA plugging and fluid loss instrument to conduct plugging and fluid loss performance tests at room temperature and a pressure difference of 3.5 MPa.
[0124] The test results are shown in Table 18 below.
[0125] Table 18:
[0126]
[0127] It can be seen from the test results in Table 18 that when the addition amount of the anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging and fluid loss amount is only 27%, indicating that the plugging performance of the anti-collapse plugging agent is poor.
[0128] Performance evaluation 7: The anti-collapse plugging agent used in this example is the product prepared in Comparative Example 2.
[0129] Compatibility with drilling fluid system: Test the influence of this product on the rheological properties of the drilling fluid system. The test method is as follows: Take common water-based drilling fluid, divide it into three portions, each portion is 400 mL. Add 4 g of anti-collapse plugging agent to one portion, and add 8 g of anti-collapse plugging agent to another portion, and conduct rheological property tests.
[0130] The test results are shown in Table 19 below.
[0131] Table 19:
[0132]
[0133] It can be seen from the test results in Table 19 that after adding the anti-collapse plugging agent to the water-based drilling fluid, the viscosity and initial and final shear of the drilling fluid system increase, and the compatibility with the drilling fluid system is poor.
[0134] Temperature resistance performance: Test the temperature resistance ability of the product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to each of the 2 portions of base slurry. For one portion, perform rheological property and filtration loss reduction property tests at room temperature, and subject the other portion to aging. The aging conditions are 150°C × 16 h, and perform rheological property and filtration loss reduction property tests after aging.
[0135] The test results are shown in Table 20 below.
[0136] Table 20:
[0137]
[0138] It can be seen from the test results in Table 20 that after the anti-collapse plugging agent is aged at 150°C for 16 h, the viscosity and initial and final shear strengths are small, and the filtration loss increases, indicating that the anti-collapse plugging agent has poor temperature resistance ability.
[0139] PPA plugging and filtration loss performance: Test the PPA plugging and filtration loss performance of the product. The test method is as follows: Prepare 2 portions of 400 mL of bentonite base slurry with a mass fraction of 5%. After curing these 2 portions of base slurry in a sealed container at 25°C ± 1°C for 24 h, add 8 g of anti-collapse plugging agent to one portion of the base slurry, and use a PPA plugging and filtration loss instrument to perform plugging and filtration loss performance tests at room temperature and a pressure difference of 3.5 MPa.
[0140] The test results are shown in Table 21 below.
[0141] Table 21:
[0142]
[0143] It can be seen from the test results in Table 21 that when the dosage of the anti-collapse plugging agent is 2%, the reduction rate of the PPA plugging and filtration loss amount is only 24%, indicating that the plugging performance of the anti-collapse plugging agent is poor.
[0144] In the above embodiments, the compatibility performance, temperature resistance performance, and PPA plugging and filtration loss performance of the drilling fluid systems in Embodiments 1 to 5 are significantly better than those of Comparative Examples 1 and 2. Thus, it can be known that 15 - 25 parts of styrene, 10 - 20 parts of acrylamide, 10 - 20 parts of n-butanol, 2 - 5 parts of emulsifier (emulsifier SP-80, OP-10), 0.3 - 0.5 parts of initiator (potassium persulfate, ammonium persulfate), 30 - 50 parts of white oil, 1 - 4 parts of dispersant (silica powder, calcium carbonate powder), and the polymerization reaction is carried out under the conditions of 40°C - 60°C, and 3 h - 4 h is the preferred reaction condition. Further, in these preferred embodiments, the PPA plugging and filtration loss performance of Embodiments 1 to 4 is better. Therefore, the temperature condition is further preferably 50°C - 60°C, and the pH is further preferably 8 - 9.
Claims
1. A sloughing prevention plugging agent, characterized in that, it comprises a polystyrene-acrylamide copolymer, an emulsifier, white oil and a dispersant.
2. The sloughing prevention plugging agent according to claim 1, characterized in that, the initiator is potassium persulfate or ammonium persulfate; the emulsifier is emulsifier SP-80 or OP-10.
3. The sloughing prevention plugging agent according to claim 1, characterized in that, the dispersant is silica powder or calcium carbonate powder.
4. The sloughing prevention plugging agent according to claim 1, characterized in that, the particle size of the dispersant is 0.02um to 0.1um.
5. A method for preparing the sloughing prevention plugging agent according to any one of claims 1-4, characterized in that, it includes: (1) Dissolve styrene and acrylamide in water, add n-butanol, and add an initiator to carry out a polymerization reaction under the condition of a pH value of 8-9; (2) Add an emulsifier and white oil and stir evenly; (3) Add a dispersant and stir evenly.
6. The method according to claim 5, characterized in that, each reaction material is added in the following mass parts: 15-25 parts of styrene, 10-20 parts of acrylamide, 10-20 parts of n-butanol, 2-5 parts of emulsifier, 0.3-0.5 parts of initiator, 30-50 parts of white oil, and 1-4 parts of dispersant.
7. The method according to claim 5, characterized in that, the polymerization reaction is carried out under the condition of 40°C - 60°C.
8. The method according to claim 7, characterized in that, the polymerization reaction is carried out under the condition of 50°C - 60°C.
9. A drilling fluid, characterized in that, it comprises the sloughing prevention plugging agent according to any one of claims 1-4.
10. Application of the sloughing prevention plugging agent according to any one of claims 1-4 in oil well plugging.