Filtrate reducer, oil-based drilling fluid, and preparation method and application of filtrate reducer and oil-based drilling fluid

Abstract

The invention provides a filtrate reducer and an oil-based drilling fluid as well as a preparation method and application of the filtrate reducer and the oil-based drilling fluid. The preparation method of the filtrate reducer comprises the following steps: mixing acrylonitrile, isobutene and acetone, heating and stirring for a first reaction, and dropwise adding fuming sulfuric acid in the heating and stirring process to obtain a first mixture; mixing N-alkyl acrylamide with the first mixture, and heating for second reaction to obtain a second mixture; dimethylaminoethyl methacrylate and the second mixture are mixed and heated for a third reaction, and a third mixture is obtained; ethyl benzene, carbon tetrachloride and the third mixture are mixed and heated for a fourth reaction, and a fourth mixture is obtained; and extracting and washing the fourth mixture with absolute ethyl alcohol to obtain a white floccule, namely the filtrate reducer. The oil-based drilling fluid comprises an oil phase, bentonite, the filtrate reducer provided by the invention, a flow pattern regulator, a weighting agent and sodium hydroxide. The oil-based drilling fluid provided by the invention has good high-temperature drop filtration performance and is suitable for drilling of deep wells and ultra-deep wells.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid technology, specifically relating to a filtration loss reducer and an oil-based drilling fluid, as well as their preparation methods and applications. Background Technology

[0002] With rapid economic development, the demand for natural gas has increased dramatically, and the contradiction between supply and demand has become increasingly prominent. Oil and gas development has expanded to deep and ultra-deep wells. However, compared with traditional shallow wells, deep and ultra-deep wells have more concealed and complex geological environments and greater uncertainty in mechanical properties, posing a greater challenge to wellbore stability. This has been a long-standing technical problem in drilling engineering.

[0003] Wellbore instability is one of the most common and complex downhole situations encountered in drilling operations, severely impacting geological data acquisition, drilling speed, drilling quality, and costs. In some new exploration areas, wellbore instability can even prevent drilling to the target formation, leading to delays in exploration and development and affecting economic benefits. The essence of wellbore instability is mechanical instability. Wellbore instability occurs when the stress on the wellbore rock exceeds its inherent strength. The causes of wellbore instability are complex, but can be mainly summarized into three aspects: mechanical factors, physicochemical factors, and engineering techniques. Formations encountered during drilling, such as shale, sandy or silty mudstone, flowstone, sandstone, argillaceous sandstone or siltstone, and igneous rocks, can all potentially experience wellbore instability.

[0004] Based on the wellbore instability phenomena encountered in practice, various technical measures for stabilizing the wellbore have been summarized. Among these, selecting the optimal drilling fluid type and suitable treatment agent is one of the important measures to improve wellbore instability. However, existing drilling fluids generally suffer from insufficient filtration performance at high temperatures. When plugging formation fractures in deep and ultra-deep wells, drilling fluids generally exhibit large filtration losses and fail to form an effective seal, allowing a large amount of drilling fluid to enter the formation, leading to wellbore instability and collapse.

[0005] Therefore, research is still needed on drilling fluid technology solutions with good high-temperature filtration reduction performance suitable for deep and ultra-deep well drilling. Summary of the Invention

[0006] The purpose of this invention is to provide a drilling fluid technology solution with good high-temperature filtration reduction performance suitable for deep and ultra-deep well drilling.

[0007] To achieve the above objectives, the present invention provides the following technical solution.

[0008] In a first aspect, the present invention provides a method for preparing a filtration loss reducing agent, wherein the method includes:

[0009] Acrylonitrile, isobutylene, and acetone were mixed and heated and stirred to carry out the first reaction. Fuming sulfuric acid was added dropwise during the heating and stirring process to obtain the first mixture.

[0010] N-alkylacrylamide is mixed with the first mixture and heated to carry out the second reaction, yielding the second mixture;

[0011] Dimethylaminoethyl methacrylate is mixed with the second mixture and heated to carry out a third reaction, yielding a third mixture.

[0012] Ethylbenzene, carbon tetrachloride, and the third mixture are mixed and heated to carry out the fourth reaction, yielding the fourth mixture.

[0013] The fourth mixture was extracted and washed with anhydrous ethanol, and the resulting white flocculent substance was the filtration loss reducer.

[0014] According to a preferred embodiment of the first aspect, preferably, the mass ratio of acetone:acrylonitrile:isobutylene:N-alkylacrylamide:dimethylaminoethyl methacrylate:ethylbenzene:carbon tetrachloride is 100:(14-16):(10-12):(20-22):(14-16):(6-8):(6-8).

[0015] According to a preferred embodiment of the first aspect, preferably, the temperature of the first reaction is 30-35°C.

[0016] According to a preferred embodiment of the first aspect, preferably, the time for the first reaction is 10-15 minutes.

[0017] According to a preferred embodiment of the first aspect, preferably, the temperature of the second reaction is 30-35°C.

[0018] According to a preferred embodiment of the first aspect, preferably, the second reaction time is 10-15 min.

[0019] According to a preferred embodiment of the first aspect, preferably, the temperature of the third reaction is 50-54°C.

[0020] According to the preferred embodiment of the first aspect, preferably, the time for the third reaction is 20-26 min.

[0021] According to the preferred embodiment of the first aspect, preferably, the temperature of the fourth reaction is 66-68°C.

[0022] According to the preferred embodiment of the first aspect, preferably, the fourth reaction time is 34-36 min.

[0023] In a second aspect, the present invention provides a filtration loss reducing agent that can be prepared using the filtration loss reducing agent preparation method provided in the first aspect.

[0024] Thirdly, the present invention provides the application of the filtration loss reducer provided in the second aspect in oil-based drilling fluids.

[0025] Fourthly, the present invention provides an oil-based drilling fluid, wherein the oil-based drilling fluid comprises an oil phase, bentonite, a filtration loss reducer, a flow pattern modifier, a weighting agent, and sodium hydroxide provided in the second aspect of the present invention;

[0026] Based on 100 parts by weight of oil phase, the composition includes 3-6 parts by weight of bentonite, 4-8 parts by weight of filtration loss reducer, 4-8 parts by weight of flow pattern modifier, 70-80 parts by weight of weighting agent, and 1-3 parts by weight of sodium hydroxide.

[0027] According to the preferred embodiment of the fourth aspect, preferably, the oil phase is white oil.

[0028] According to the preferred embodiment of the fourth aspect, xanthan gum is preferably selected as the flow pattern regulator.

[0029] According to the preferred embodiment of the fourth aspect, preferably, the weighting agent is barite.

[0030] Fifthly, the present invention provides a method for preparing the oil-based drilling fluid provided in the fourth aspect, wherein the method includes:

[0031] The oil phase, bentonite, the filtration loss reducer, flow pattern modifier, weighting agent and sodium hydroxide provided in the second aspect of the present invention are mixed to obtain the oil-based drilling fluid.

[0032] According to a preferred embodiment of the fifth aspect, preferably, the oil phase, bentonite, the filtration loss reducer, flow pattern modifier, weighting agent, and sodium hydroxide provided in the second aspect of the present invention are mixed in the following manner:

[0033] Bentonite, a modified filtration reducer, a flow pattern modifier, a weighting agent, and sodium hydroxide were added sequentially to the oil phase under stirring conditions.

[0034] In a sixth aspect, the present invention provides the application of the oil-based drilling fluid provided in the fourth aspect in drilling operations in formations with unstable wellbore.

[0035] The oil-based drilling fluid provided by this invention is a wellbore-stabilizing oil-based drilling fluid, formulated by combining a novel filtration reducer with other additives. The oil-based drilling fluid with the addition of this novel filtration reducer exhibits minimal viscosity increase and excellent filtration reduction performance, maintaining superior filtration reduction properties even at temperatures above 180°C, making it well-suited for deep and ultra-deep well drilling. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0037] Example 1

[0038] This embodiment provides a filtration loss reducer G1 and an oil-based drilling fluid A1.

[0039] Filtration loss reducer G1 was prepared by the following method:

[0040] S1. Pour acetone into a three-necked flask, add acrylonitrile and isobutylene to the acetone, heat and stir to carry out the first reaction, and add fuming sulfuric acid dropwise during the stirring process to obtain the first mixture; wherein, the temperature of the first reaction is 33℃ and the time of the first reaction is 13 minutes.

[0041] S2. N-alkylacrylamide is added to the first mixture, and the mixture is heated and stirred to carry out a second reaction to obtain a second mixture; wherein, the temperature of the second reaction is 33°C and the time of the second reaction is 13 minutes;

[0042] S3. Add dimethylaminoethyl methacrylate to the second mixture, heat and stir to carry out the third reaction, and obtain the third mixture; wherein, the temperature of the third reaction is 52℃ and the time of the third reaction is 23 minutes;

[0043] S4. Ethylbenzene and carbon tetrachloride are mixed and added to the third mixture. The mixture is heated and stirred to carry out the fourth reaction, resulting in the fourth mixture. The temperature of the fourth reaction is 67°C and the reaction time is 35 minutes.

[0044] S5. The fourth mixture is extracted and washed with anhydrous ethanol to obtain a white flocculent substance, which is the filtration loss reducing agent G1.

[0045] The mass ratio of acetone:acrylonitrile:isobutylene:N-alkylacrylamide:dimethylaminoethyl methacrylate:ethylbenzene:carbon tetrachloride is 100:15:11:21:15:7:7.

[0046] Oil-based drilling fluid A1 is prepared by the following method:

[0047] Pour 100 parts by weight of white oil into an enamel measuring cup. Under stirring conditions, add 4 parts by weight of bentonite, 6 parts by weight of filtration loss reducer G1, 6 parts by weight of xanthan gum, 75 parts by weight of barite, and 2 parts by weight of sodium hydroxide to the white oil to prepare wellbore stabilized oil-based drilling fluid A1.

[0048] Example 2

[0049] This embodiment provides a filtration loss reducer G2 and an oil-based drilling fluid A2.

[0050] Filtration loss reducer G2 was prepared by the following method:

[0051] S1. Pour acetone into a three-necked flask, add acrylonitrile and isobutylene to the acetone, heat and stir to carry out the first reaction, and add fuming sulfuric acid dropwise during the stirring process to obtain the first mixture; wherein, the temperature of the first reaction is 30°C and the time of the first reaction is 10 minutes.

[0052] S2. N-alkylacrylamide is added to the first mixture, and the mixture is heated and stirred to carry out a second reaction to obtain a second mixture; wherein, the temperature of the second reaction is 30°C and the time of the second reaction is 10 minutes;

[0053] S3. Add dimethylaminoethyl methacrylate to the second mixture, heat and stir to carry out the third reaction, and obtain the third mixture; wherein, the temperature of the third reaction is 50℃ and the time of the third reaction is 20 minutes;

[0054] S4. Ethylbenzene and carbon tetrachloride are mixed and added to the third mixture. The mixture is heated and stirred to carry out the fourth reaction, resulting in the fourth mixture. The temperature of the fourth reaction is 66°C and the reaction time is 34 minutes.

[0055] S5. The fourth mixture is extracted and washed with anhydrous ethanol to obtain a white flocculent substance, which is the filtration loss reducing agent G2.

[0056] The mass ratio of acetone:acrylonitrile:isobutylene:N-alkylacrylamide:dimethylaminoethyl methacrylate:ethylbenzene:carbon tetrachloride is 100:14:10:20:14:6:6.

[0057] Oil-based drilling fluid A2 is prepared by the following method:

[0058] Pour 100 parts by weight of white oil into an enamel measuring cup. Under stirring conditions, add 4 parts by weight of bentonite, 6 parts by weight of filtration loss reducer G2, 6 parts by weight of xanthan gum, 75 parts by weight of barite, and 2 parts by weight of sodium hydroxide to the white oil to prepare wellbore stabilized oil-based drilling fluid A2.

[0059] Example 3

[0060] This embodiment provides a filtration loss reducer G3 and an oil-based drilling fluid A3.

[0061] Filtration loss reducer G3 was prepared by the following method:

[0062] S1. Pour acetone into a three-necked flask, add acrylonitrile and isobutylene to the acetone, heat and stir to carry out the first reaction, and add fuming sulfuric acid dropwise during the stirring process to obtain the first mixture; wherein, the temperature of the first reaction is 35℃ and the time of the first reaction is 15 minutes.

[0063] S2. Add N-alkylacrylamide to the first mixture, heat and stir to carry out the second reaction, and obtain the second mixture; wherein, the temperature of the second reaction is 35°C and the time of the second reaction is 15 minutes;

[0064] S3. Add dimethylaminoethyl methacrylate to the second mixture, heat and stir to carry out the third reaction, and obtain the third mixture; wherein, the temperature of the third reaction is 54℃ and the time of the third reaction is 26 minutes;

[0065] S4. Ethylbenzene and carbon tetrachloride are mixed and added to the third mixture. The mixture is heated and stirred to carry out the fourth reaction, resulting in the fourth mixture. The temperature of the fourth reaction is 68°C and the reaction time is 36 minutes.

[0066] S5. The fourth mixture is extracted and washed with anhydrous ethanol to obtain a white flocculent substance, which is the filtration loss reducing agent G3.

[0067] The mass ratio of acetone:acrylonitrile:isobutylene:N-alkylacrylamide:dimethylaminoethyl methacrylate:ethylbenzene:carbon tetrachloride is 100:16:12:22:16:8:8.

[0068] Oil-based drilling fluid A3 is prepared by the following method:

[0069] Pour 100 parts by weight of white oil into an enamel measuring cup. Under stirring conditions, add 4 parts by weight of bentonite, 6 parts by weight of filtration loss reducer G3, 6 parts by weight of xanthan gum, 75 parts by weight of barite, and 2 parts by weight of sodium hydroxide to the white oil to prepare wellbore stabilized oil-based drilling fluid A3.

[0070] Experimental Example

[0071] In this experiment, a high-temperature and high-pressure filtration tester was used to test the filtration performance of oil-based drilling fluid A1, oil-based drilling fluid A2, and oil-based drilling fluid A3, respectively.

[0072] The testing steps are as follows:

[0073] Take 300 mL of the sample to be tested, age it at 180℃ for 24 hours, and then place it in a high temperature and high pressure filtration tester to test its filtration performance. The test pressure is 3.5 MPa, the temperature is 180℃, and the time is half an hour. The experimental results are shown in Table 1.

[0074] Table 1

[0075] experimental group Filtration loss (ml) A1 2 A2 3 A3 3

[0076] As can be seen from Table 1, the oil-based drilling fluid provided by the present invention, after being aged at 180°C for 24 hours and then tested for filtration loss at a pressure of 3.5 MPa and a temperature of 180°C, showed that the filtration loss after half an hour did not exceed 5 ml, indicating that it has good filtration loss reduction performance and good high-temperature stability.

[0077] The embodiments described above are for the purpose of better explaining the present invention. For those skilled in the art, it is not difficult to make various modifications to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and variations made to the present invention by those skilled in the art based on the principles and spirit of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a filtration loss reducing agent, wherein, The method includes: Acrylonitrile, isobutylene, and acetone were mixed and heated and stirred to carry out the first reaction. Fuming sulfuric acid was added dropwise during the heating and stirring process to obtain the first mixture. N-alkylacrylamide is mixed with the first mixture and heated to carry out the second reaction, yielding the second mixture; Dimethylaminoethyl methacrylate is mixed with the second mixture and heated to carry out a third reaction, yielding a third mixture. Ethylbenzene, carbon tetrachloride, and the third mixture are mixed and heated to carry out the fourth reaction, yielding the fourth mixture. The fourth mixture was extracted and washed with anhydrous ethanol, and the resulting white flocculent substance was the filtration loss reducer.

2. The method for preparing the filtration loss reducing agent according to claim 1, wherein, By mass ratio, acetone:acrylonitrile:isobutylene:N-alkylacrylamide:dimethylaminoethyl methacrylate:ethylbenzene:carbon tetrachloride = 100:(14-16):(10-12):(20-22):(14-16):(6-8):(6-8).

3. The method for preparing the filtration loss reducing agent according to claim 1, wherein, The temperature of the first reaction is 30-35℃; and / or The first reaction time is 10-15 minutes.

4. The method for preparing the filtration loss reducing agent according to claim 1, wherein, The temperature of the second reaction is 30-35℃; and / or The second reaction takes 10-15 minutes.

5. The method for preparing the filtration loss reducing agent according to claim 1, wherein, The temperature of the third reaction is 50-54℃; and / or The third reaction takes 20-26 minutes.

6. The method for preparing the filtration loss reducing agent according to claim 1, wherein, The temperature for the fourth reaction is 66-68℃; and / or The fourth reaction takes 34-36 minutes.

7. A filtration loss reducing agent, which can be prepared by the method for preparing the filtration loss reducing agent according to any one of claims 1-6.

8. The application of the filtration loss reducer according to claim 7 in oil-based drilling fluids.

9. An oil-based drilling fluid, wherein, The oil-based drilling fluid comprises an oil phase, bentonite, the filtration loss reducer as described in claim 7, a flow pattern modifier, a weighting agent, and sodium hydroxide; Based on 100 parts by weight of oil phase, the composition includes 3-6 parts by weight of bentonite, 4-8 parts by weight of filtration loss reducer, 4-8 parts by weight of flow pattern modifier, 70-80 parts by weight of weighting agent, and 1-3 parts by weight of sodium hydroxide.

10. The oil-based drilling fluid according to claim 9, wherein, White oil was selected as the oil phase.

11. The oil-based drilling fluid according to claim 9, wherein, Xanthan gum was selected as the flow conditioner.

12. The oil-based drilling fluid according to claim 9, wherein, Barite is selected as the weighting agent.

13. The method for preparing the oil-based drilling fluid according to any one of claims 9-12, wherein, The method includes: The oil phase, bentonite, the filtration loss reducer, flow pattern modifier, weighting agent and sodium hydroxide provided in the second aspect of the present invention are mixed to obtain the oil-based drilling fluid.

14. The application of the oil-based drilling fluid according to any one of claims 9-12 in drilling operations in formations with unstable wellbore.