Preparation method of brine slurry
By adding specific substances to the brine cement slurry to form a stable mud treatment agent, the problem of poor stability of brine cement slurry in a high-salt environment is solved, and its effective application in brine formations and ultra-deep wells is achieved.
Patent Information
- Application Number
- CN202510041459.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-10
- Publication Date
- 2025-04-29
AI Technical Summary
Existing brine cement slurries are easily contaminated in high-salt environments, resulting in a decrease in viscosity and shear force, an increase in filtration loss, and a loss of stability, making it difficult to effectively use in brine formations and ultra-deep wells.
By stirring bentonite with sodium carbonate evenly, sodium salt bentonite is formed, and prehydrated in brine, followed by adding anti-salt water-reducing agent, modified polyanionic cellulose, sulfonated phenolic resin, industrial salt and potassium chloride and other substances to form a slurry treatment agent, adjusting the pH value to 9-10, and brine cement slurry with anti-salt pollution, calcium and high temperature resistance are prepared.
This method allows the brine cement slurry to remain stable in a high-salt environment, improves its application capabilities in brine formations and ultra-deep wells, and ensures the stability of the well wall and the safety of drilling operations.
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Figure CN119899645A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of brine cement slurry, in particular to a method for preparing brine cement slurry. Background Art
[0002] The composition and performance characteristics of ordinary mud determine that its performance is unstable and easily contaminated by clay, mud, sand and salt. When crossing coastal and brine formations, the salt debris in the formation will enter the mud and dissolve rapidly. At the same time, if the hydrostatic pressure of the mud is not enough to suppress the high-pressure brine flow, the brine flow will invade the mud and cause the NaCl content to increase rapidly, causing the mud to be contaminated. The viscosity, shear force and filtration loss of the mud will increase rapidly with the increase of NaCl content. When the salt content increases to a certain value, the viscosity and shear force reach the maximum value. However, when the salt content exceeds a certain value, its viscosity and shear force will decrease with the increase of NaCl content, and the filtration loss will continue to increase.
[0003] When brine invades the mud, the mechanism of the mud performance changes with the increase of NaCl concentration in the mud, the concentration of Na+ is getting higher and higher, so the phenomenon of "squeezing" the double electric layer occurs, the electromotive force of the clay particles is reduced, and the hydration film becomes thinner. In this case, due to the thermal motion of the clay particles, they collide with each other to form floccules, and the performance is that the viscosity and shear force of the mud increase rapidly. When the NaCl content continues to increase, the squeezing of the double electric layer phenomenon becomes more serious, the electromotive force is further reduced, the hydration film becomes extremely thin, and the clay particles aggregate and become larger, so the dispersion of the clay particles is significantly reduced, causing the viscosity and shear force to decrease, and the filtration loss continues to increase. The clay particles aggregate and sink. In this case, the viscosity and shear force of the mud drop to very low values, and the filtration loss continues to increase, resulting in the segregation of the mud and its complete loss of stability.
[0004] Brine cement slurry is a complex but efficient process, especially suitable for drilling operations when horizontal directional drilling passes through brine formations. In addition, brine cement slurry can effectively inhibit hydration of shale, ensure the stability of the well wall and prevent collapse; it can inhibit formation slurrying, so that the mud fluid maintains good performance, especially fluidity and stability; it also has the characteristics of strong suspension ability and barite in high-density mud fluid is not easy to precipitate; at the same time, it has less damage to the permeability of the oil layer.
[0005] However, when using brine cement slurry, some issues need to be noted. In particular, the salt content needs to be strictly controlled, generally above 1.3 million ppm, but not too high. Because the pH value of brine cement slurry will decrease with the increase of salt content, which will affect the stability of the slurry. In order to maintain a certain pH value, caustic soda needs to be added in time. Usually, the pH value of brine cement slurry should be kept between 9.5-11.0.
[0006] Therefore, brine cement slurry can solve the problems encountered in drilling in brine formations by providing cations to inhibit the hydration and dispersion of clay particles, forming a stable coarse dispersion system. At the same time, it also has multiple advantages, making drilling operations more efficient and safer. Summary of the invention
[0007] In view of the deficiencies in the prior art, the present invention provides a method for preparing brine cement slurry. The brine cement slurry has the ability to resist salt pollution, calcium and high temperature, and is suitable for use in brine formations and ultra-deep wells.
[0008] A method for preparing brine mud comprises the following raw materials: brine, bentonite and mud treating agent.
[0009] The brine slurry preparation method is as follows: Stir bentonite and sodium carbonate in a mass ratio of 100:(5-6) evenly to obtain sodium bentonite, prehydrate the sodium bentonite for 8-10 hours, add brine after treatment, then add mud treatment agent, stir evenly, adjust the pH to 9-10 with caustic soda to obtain brine mud.
[0010] Preferably, the mass ratio of the brine, sodium bentonite and mud treating agent is 100:(2-4):(1.4-1.6).
[0011] Preferably, the mud treating agent comprises: a salt-resistant fluid loss reducer, modified polyanionic cellulose, sulfonated phenolic resin, industrial salt and potassium chloride in a mass ratio of 1:(0.9-1.1):(0.9-1.1):(2-4):(4-8).
[0012] Preferably, the preparation method of the modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 20-30° C. for 4-6 hours to obtain activated cellulose.
[0013] Step 2: Add maleic anhydride to the reactor, add N,N-dimethylformamide under stirring, stir evenly, add activated cellulose, mix well, heat to 60-80°C, react for 4-6h, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0014] Step 3: Add N,N-dimethylformamide to a reaction vessel, then add the polyanionic cellulose intermediate and vinyl pyrrolidone to the reaction vessel, stir, introduce pure nitrogen, heat to 40-50°C, then add potassium persulfate, react at 60-70°C for 6-8h, precipitate with acetone, wash with acetone, and vacuum dry for 24-36h to obtain modified polyanionic cellulose.
[0015] Preferably, in step 2, the mass ratio of maleic anhydride to cellulose is (1-1.2):1.
[0016] Preferably, in step 3, the mass ratio of the polyanionic cellulose intermediate, vinyl pyrrolidone and potassium persulfate is 20:(10-12):(0.12-0.15).
[0017] Beneficial technical effects: The invention mixes salt-resistant fluid loss reducer, modified polyanionic cellulose, sulfonated phenolic resin, industrial salt and potassium chloride to obtain mud treating agent, stirs bentonite and sodium carbonate evenly to obtain sodium bentonite, adds sodium bentonite into brine, and then adds mud treating agent to obtain brine mud.
[0018] The present invention adds salt-resistant fluid loss reducer, modified polyanionic cellulose, sulfonated phenolic resin, industrial salt, potassium chloride and other substances into the mud liquid. These substances are adsorbed around clay particles to form a protective layer, so that the clay particles remain stable and a stable coarse dispersion system is formed. The brine mud slurry has salt pollution resistance, calcium resistance and high temperature resistance, and is suitable for use in brine formations and ultra-deep wells. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is the preparation process of modified polyanionic cellulose.
[0020] Figure 2 This is the phenomenon of the test in Examples 1-3 where the proportion of the mud treatment agent in the brine mud was 1.5% and 3%.
[0021] Figure 3 The test was conducted in Example 1 where the proportion of the mud treating agent in the brine mud was 3%.
[0022] Figure 4 The test was conducted in Example 1 where the proportion of the mud treating agent in the brine mud was 1.5%. DETAILED DESCRIPTION Example 1
[0023] (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0024] The mud treating agent comprises 1g of salt-resistant fluid loss reducing agent, 1.1g of modified polyanionic cellulose, 1.1g of sulfonated phenolic resin, 4g of industrial salt and 8g of potassium chloride.
[0025] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 20°C for 6 hours to obtain activated cellulose.
[0026] Step 2: Add 3.6 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 80°C, react for 4 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0027] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 12 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 50°C, then add 0.15 g of potassium persulfate, react at 70°C for 6 h, precipitate with acetone, wash with acetone, and vacuum dry for 36 h to obtain modified polyanionic cellulose.
[0028] (3) Add 0.48 g of sodium carbonate to 8 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 3.2 g of mud treatment agent and stir well. Adjust the pH to 9 with caustic soda to obtain brine mud. Example 2
[0029] (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0030] The mud treating agent comprises 1g of salt-resistant fluid loss reducing agent, 0.9g of modified polyanionic cellulose, 1.1g of sulfonated phenolic resin, 4g of industrial salt and 8g of potassium chloride.
[0031] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 30° C. for 4 h to obtain activated cellulose.
[0032] Step 2: Add 3 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 60°C, react for 6 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0033] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 10 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 40°C, then add 0.12 g of potassium persulfate, react at 60°C for 8 h, precipitate with acetone, wash with acetone, and vacuum dry for 24 h to obtain modified polyanionic cellulose.
[0034] (3) Add 0.2 g of sodium carbonate to 4 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 8 h, add 200 g of brine after treatment, and then add 2.8 g of mud treatment agent and stir well. Adjust the pH to 10 with caustic soda to obtain brine mud. Example 3
[0035] (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0036] The mud treating agent comprises 1g of salt-resistant fluid loss reducing agent, 0.9g of modified polyanionic cellulose, 1.1g of sulfonated phenolic resin, 4g of industrial salt and 8g of potassium chloride.
[0037] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 30°C for 6 hours to obtain activated cellulose.
[0038] Step 2: Add 3.6 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 80°C, react for 6 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0039] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 11 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 150°C, add 0.12 g of potassium persulfate, react at 70°C for 8 h, precipitate with acetone, wash with acetone, and vacuum dry for 36 h to obtain modified polyanionic cellulose.
[0040] (3) Add 0.4 g of sodium carbonate to 6 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 2.8 g of mud treatment agent and stir well. Adjust the pH to 10 with caustic soda to obtain brine mud. Example 4
[0041] (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0042] The mud treating agent comprises 1g of salt-resistant fluid loss reducing agent, 1g of modified polyanionic cellulose, 1.1g of sulfonated phenolic resin, 4g of industrial salt and 8g of potassium chloride.
[0043] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 20°C for 4 hours to obtain activated cellulose.
[0044] Step 2: Add 3.6 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 60°C, react for 6 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0045] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 10 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 50°C, then add 0.12 g of potassium persulfate, react at 70°C for 8 h, precipitate with acetone, wash with acetone, and vacuum dry for 24 h to obtain modified polyanionic cellulose.
[0046] (3) Add 0.48 g of sodium carbonate to 8 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 3.2 g of mud treatment agent and stir well. Adjust the pH to 10 with caustic soda to obtain brine mud.
[0047] Comparative Example 1: (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0048] The mud treating agent includes 1g of salt-resistant fluid loss reducer and 1.1g of modified polyanionic cellulose.
[0049] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 20°C for 6 hours to obtain activated cellulose.
[0050] Step 2: Add 3.6 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 80°C, react for 4 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0051] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 12 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 50°C, then add 0.15 g of potassium persulfate, react at 70°C for 6 h, precipitate with acetone, wash with acetone, and vacuum dry for 36 h to obtain modified polyanionic cellulose.
[0052] (3) Add 0.48 g of sodium carbonate to 8 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 3.2 g of mud treatment agent and stir well. Adjust the pH to 9 with caustic soda to obtain brine mud.
[0053] Comparative Example 2: (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0054] The mud treating agent comprises 1g of salt-resistant fluid loss reducer, 1.1g of modified polyanionic cellulose and 1.1g of sulfonated phenolic resin.
[0055] (2) The preparation method of modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate it at 20°C for 6 hours to obtain activated cellulose.
[0056] Step 2: Add 3.6 g of maleic anhydride into the reactor, add 100 mL of N, N-dimethylformamide while stirring, stir evenly, add 3 g of activated cellulose, mix well, heat to 80°C, react for 4 hours, then add sodium hydroxide solution, filter after the reaction, wash, and dry to obtain a polyanionic cellulose intermediate.
[0057] Step 3: Add 200 mL of N,N-dimethylformamide into a reaction vessel, then add 20 g of a polyanionic cellulose intermediate and 12 g of vinyl pyrrolidone into the reaction vessel, stir, introduce pure nitrogen, heat to 50°C, then add 0.15 g of potassium persulfate, react at 70°C for 6 h, precipitate with acetone, wash with acetone, and vacuum dry for 36 h to obtain modified polyanionic cellulose.
[0058] (3) Add 0.48 g of sodium carbonate to 8 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 3.2 g of mud treatment agent and stir well. Adjust the pH to 9 with caustic soda to obtain brine mud.
[0059] Comparative Example 3: (1) A method for preparing brine mud, comprising the following raw materials: brine, bentonite, and mud treating agent.
[0060] The mud treating agent includes 1g of salt-resistant fluid loss reducer, 1.1g of sulfonated phenolic resin, 4g of industrial salt and 8g of potassium chloride.
[0061] (2) Add 0.48 g of sodium carbonate to 8 g of bentonite and stir well to obtain sodium bentonite. Prehydrate the sodium bentonite for 10 h, add 200 g of brine after treatment, and then add 3.2 g of mud treatment agent and stir well. Adjust the pH to 9 with caustic soda to obtain brine mud.
[0062] During the test, the proportion of the mud treating agent in the products of Example 1 and Comparative Examples 1-3 in the brine mud was calculated to be 1.5%, and then the mud was successfully prepared and placed for 12 hours before observation.
[0063] The amount of the mud treating agent in the products of Example 1 and Comparative Examples 1-3 was doubled so that the proportion of the mud treating agent in the products of Example 1 and Comparative Examples 1-3 in the brine mud was 3%. After the mud was successfully prepared and placed for 12 hours, it was observed.
[0064] Table 1 shows the phenomenon of different proportions of mud treatment agent in brine mud Mud treatment agent accounts for 1.5% in brine mud Mud treatment agent accounts for 3% in brine mud Example 1 The fluid loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are excellent. The water loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are good. Example 2 The fluid loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are excellent. The water loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are good. Example 3 The fluid loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are excellent. The water loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are good. Example 4 The fluid loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are excellent. The water loss reduction effect is obvious, the viscosity is high, and the viscosity, sedimentation and anti-segregation effects of the mud are good. Comparative Example 1 The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious Comparative Example 2 The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious Comparative Example 3 The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious The effect of reducing fluid loss is not obvious, mud segregation, sedimentation, and stratification are obvious ; It can be seen from Table 1 that the embodiment has a high fluid loss reduction effect and high viscosity, and the viscosity, sedimentation and anti-segregation effect of the mud are better than those of Comparative Examples 1-3. When the mud treating agent accounts for 1.5% of the brine mud, the performance of the brine mud is the best, which is better than when the mud treating agent accounts for 3% of the brine mud.
[0065] The modified polyanionic cellulose in the product has added double bonds and ring structures, which can increase the fluid loss reduction effect of the mud, plastic viscosity, form a stable suspension, help improve the mud's ability to carry drill cuttings, maintain the stability of the well wall, and make the brine mud resistant to salt pollution, as well as calcium and high temperature resistance; sulfonated phenolic resin is usually used as a cement fluid loss reducer. It forms a non-permeable membrane between the cement and the formation to reduce the permeability of the filter cake, thereby reducing the water loss. In addition, it can also improve the distribution of cement particles and form a denser filter cake structure; salt-resistant fluid loss reducers are used to improve the salt resistance of mud and reduce water loss in high-salinity environments. It can improve the viscosity and colloidal stability of the mud, thereby maintaining the stability of the well wall and reducing pollution to the formation water; industrial salt acts as an electrolyte in the mud, which can adjust the conductivity and ion concentration of the mud, affecting the chemical properties and physical stability of the mud; potassium chloride is often used as a shale inhibitor in the mud to help control the hydration expansion of mud shale and maintain the stability of the well wall. At the same time, potassium chloride can also act as an electrolyte to adjust the conductivity and ionic strength of the mud.
[0066] Therefore, Comparative Example 1 lacks sulfonated phenolic resin, industrial salt, and potassium chloride; Comparative Example 2 lacks industrial salt and potassium chloride; Comparative Example 3 lacks modified polyanionic cellulose, so that the performance of Comparative Examples 1-3 is not as good as that of Example 1; and when the mud treating agent accounts for 1.5% of the brine cement slurry, the performance of the brine cement slurry is the best, which is better than the mud treating agent accounting for 3% of the brine cement slurry, indicating that when the mud treating agent accounts for 3% of the brine cement slurry, the mud treating agent is excessive, which reduces the water loss reduction effect of the brine cement slurry, the viscosity of the mud, the precipitation and the anti-segregation effect.
Claims
1. A method for preparing brine slurry, characterized in that: Includes the following raw materials: brine, bentonite, mud treatment agent; The brine slurry preparation method is as follows: Add sodium carbonate to bentonite and stir evenly to obtain sodium bentonite. Prehydrate the sodium bentonite base for 8-10 hours, add brine after treatment, then add mud treatment agent, stir evenly, adjust the pH to 9-10 with caustic soda to obtain brine mud.
2. The method for preparing brine slurry according to claim 1, characterized in that: The mass ratio of the bentonite to sodium carbonate is 100:(5-6).
3. The method for preparing brine slurry according to claim 1, characterized in that: The mass ratio of the brine, sodium bentonite and mud treating agent is 100:(2-4):(1.4-1.6).
4. The method for preparing brine slurry according to claim 1, characterized in that: The mud treatment agent comprises: a salt-resistant fluid loss reducer, modified polyanionic cellulose, sulfonated phenolic resin, industrial salt and potassium chloride in a mass ratio of 1:(0.9-1.1):(0.9-1.1):(2-4):(4-8).
5. The method for preparing brine slurry according to claim 4, characterized in that: The preparation method of the modified polyanionic cellulose is: Step 1: Add cellulose to tetrahydrofuran and activate at 20-30° C. for 4-6 hours to obtain activated cellulose; Step 2: Add maleic anhydride to the reactor, add plasticizer N,N-dimethylformamide under stirring, stir evenly, add activated cellulose, mix well, heat to 60-80°C, react for 4-6h, then add sodium hydroxide solution, filter after reaction, wash, and dry to obtain a polyanionic cellulose intermediate; Step 3: Add N,N-dimethylformamide to a reaction vessel, then add the polyanionic cellulose intermediate and vinyl pyrrolidone to the reaction vessel, stir, introduce pure nitrogen, heat to 40-50°C, then add potassium persulfate, react at 60-70°C for 6-8h, precipitate with acetone, wash with acetone, and vacuum dry for 24-36h to obtain modified polyanionic cellulose.
6. The method for preparing brine slurry according to claim 5, characterized in that: In step 2, the mass ratio of maleic anhydride to cellulose is (1-1.2):
1.
7. The method for preparing brine slurry according to claim 5, characterized in that: In step 3, the mass ratio of the polyanionic cellulose intermediate to vinyl pyrrolidone is 20:(10-12):(0.12-0.15).