High-temperature-resistant filtrate reducer as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant filtrate reducer as well as a preparation method and application thereof. The filtrate reducer is prepared from the following raw materials in parts by weight: 10 parts of maleic anhydride, 0-5 parts of isobutene, 0.8-27 parts of long-chain alpha-olefin and 0.1-3.7 parts of an initiator. The preparation method of the filtrate reducer comprises the following steps: S1, sequentially adding maleic anhydride, an initiator, long-chain alpha-olefin and a solvent, stirring for dissolving, adding isobutene, and heating for reaction; s2, cooling the reaction liquid in the S1 to room temperature, pouring the reaction liquid into normal hexane, and separating out a solid; and S3, filtering and washing the solid separated out in the step S2, and drying and crushing the washed solid to obtain the filtrate reducer. The high-temperature-resistant filtrate reducer provided by the invention is applied to gas-to-oil synthetic base drilling fluid, and not only has a good high-temperature and high-pressure filtrate reduction effect, but also is relatively good in temperature resistance and relatively low in filter loss. The filtrate reducer also solves the problems of large filter loss, poor rheological property, easy settlement of barite, environmental pollution and the like of a gas-to-oil synthetic base drilling fluid system under the conditions of high temperature and high pressure.

Description

Technical Field

[0001] The invention relates to a high temperature resistant fluid loss reducer and a preparation method and application thereof. Background Art

[0002] In recent years, with the improvement of drilling technology, the exploration and development of oil and gas resources has continued to develop towards deep formations. Drilling fluid plays a vital role in the entire drilling process. Among them, gas-to-liquid synthetic-based drilling fluid has the advantages of high temperature resistance, salt and calcium invasion resistance, good well wall stability, good lubricity and little damage to oil and gas layers. It has gradually become the first choice for drilling deep wells, ultra-deep wells, high-angle directional wells, multi-branch wells and horizontal wells and other complex formation wells. As a key component in the gas-to-liquid synthetic-based drilling fluid system, the main function of the fluid loss reducer is to form a thin and dense mud cake on the well wall, reduce the filtration loss, maintain wellbore stability, and reduce the invasion of the drilling fluid liquid and solid phase into the formation and damage to the oil and gas layer. It is one of the indispensable treatment agents in the drilling fluid.

[0003] At present, the existing fluid loss reducers for gas-to-liquid synthetic drilling fluids are mainly divided into asphalt, humic acid amine, other natural polymer modified and polymer. Among them, asphalt fluid loss reducers have the advantages of wide material availability and low price, and have been widely used in the past. However, asphalt fluid loss reducers have the disadvantages of reducing drilling speed, polluting the environment and requiring large dosage. Their use has been restricted in gas-to-liquid synthetic drilling fluid formulations in environmentally sensitive areas in China and most parts of the world. Humic acid amine fluid loss reducers are environmentally friendly and can improve drilling fluid rheology and emulsification stability, but they are easily decomposed and lose their function under high temperature conditions, and their overall temperature control performance is poor compared to asphalt. For example, the performance test results of the humic acid-based filtrate reducer prepared in the article "Development and Performance of a New High-Temperature Resistant Oil-Based Drilling Fluid Filter Loss Reducer" (Drilling Fluids and Completion Fluids, 2016, 33(01)) in high-temperature resistant and high-density oil-based drilling fluid showed that the high-temperature and high-pressure filtration loss of the filtrate reducer was 4.0 ml at 180°C and 8.6 ml at 220°C, indicating that the high-temperature resistance needs to be improved.

[0004] High molecular polymer fluid loss reducers are environmentally friendly, have low fluid loss under high temperature and high pressure, and have long service life at high temperature. The main chain of polymer fluid loss reducers is a carbon-carbon structure, so they have good temperature resistance. Through molecular structure design and functionalized side chains, the fluid loss reducers can have the dual effects of fluid loss reduction and plugging while drilling. In the article "Study on the Effect of PIBSI on the Performance of Oil-Based Drilling Fluids" (Journal of Petrochemical Colleges and Universities, 2014, 27(04)), it was found during experimental research that: under high temperature conditions, different mass fractions of PIBSI were added to different oil-based drilling fluid systems, and the rheological properties of each system at 65°C were studied, and the effect of PIBSI on the performance of two oil-based drilling fluid systems under high temperature conditions was studied. Especially under 150°C, the fluid loss of the fluid loss reducer at high temperature and high pressure was average. In addition, the existing high molecular polymer gas-to-oil synthetic-based fluid loss reducers mainly rely on imports and are expensive, which seriously limits their large-scale application.

[0005] Therefore, it is urgent to develop a polymer fluid loss reducer with a new structure and good fluid loss reduction performance under high temperature conditions. Summary of the invention

[0006] In order to at least partially solve the above technical problems, the present invention provides a fluid loss reducer with good temperature resistance, low fluid loss under high temperature and high pressure, and good fluid loss effect, as well as a preparation method and application thereof.

[0007] As one aspect of the present invention, it relates to a high temperature resistant fluid loss reducer, which comprises the following raw materials in parts by weight: 10 parts of maleic anhydride, 0 to 5 parts of isobutylene, 0.8 to 27 parts of long-chain α-olefin, and 0.1 to 3.7 parts of initiator.

[0008] In a specific embodiment, the fluid loss reducer further comprises 30 to 60 parts of a solvent.

[0009] In a specific embodiment, the solvent is selected from organic acid alkyl esters and / or aromatic hydrocarbons.

[0010] In a specific embodiment, the long-chain α-olefin is selected from α-olefins having 6 to 19 carbon atoms.

[0011] In a specific embodiment, the initiator is a thermal decomposition initiator.

[0012] In a specific embodiment, the thermal decomposition initiator is selected from one or more of dibenzoyl peroxide, diisopropyl peroxide, di-tert-butyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicarbonyl peroxide, azobisisobutyronitrile, azobisisovaleronitrile and azobisisoheptonitrile.

[0013] As another aspect of the present invention, it relates to a method for preparing the above-mentioned high temperature resistant fluid loss reducer, the method comprising the following steps:

[0014] S1, add maleic anhydride, initiator, long-chain α-olefin and solvent in sequence, stir to dissolve, add isobutylene, and heat to react;

[0015] S2, after the reaction solution of S1 is cooled to room temperature, it is poured into n-hexane, after the reaction solution of S1 is cooled to room temperature, it is poured into n-hexane to precipitate solid;

[0016] S3, filtering and washing the solid precipitated in S2, drying and crushing the washed solid to obtain a filtrate reducer.

[0017] In a specific embodiment, in S1, the inert gas is selected from one or more of nitrogen, helium and argon.

[0018] In a specific embodiment, in S1, the reaction temperature is 50-80° C. and the reaction time is 3-6 hours.

[0019] As another aspect of the present invention, it relates to the use of the above-mentioned high temperature resistant fluid loss reducer in gas-to-liquid synthetic-based drilling fluid.

[0020] As another aspect of the present invention, it relates to a gas-to-liquid synthetic-based drilling fluid, wherein the gas-to-liquid synthetic-based drilling fluid contains the above-mentioned high-temperature resistant fluid loss reducer.

[0021] As another aspect of the present invention, it relates to an oilfield drilling process, wherein the drilling process uses the above-mentioned gas-to-liquid synthetic-based drilling fluid.

[0022] The high temperature resistant fluid loss reducer provided by the present invention is suitable for a gas-to-liquid synthetic-based drilling fluid system, and not only has a good high temperature and high pressure fluid loss reduction effect, but also has good temperature resistance and low fluid loss. The fluid loss reducer solves the problems of large fluid loss, poor rheological properties, easy sedimentation of barite and environmental pollution in a gas-to-liquid synthetic-based drilling fluid system under high temperature and high pressure conditions.

[0023] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the infrared spectrum of the fluid loss reducer prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with specific examples, and the protection scope of this application is not limited by the following examples. The sources of materials mainly involved in the following examples are shown in Table 1 below, and other materials not shown are conventional commercial products.

[0026] Table 1: Material source description

[0027]

[0028]

[0029] Hereinafter, the inventors provide Examples 1 to 4 by further studying the high molecular polymer fluid loss reducer and the preparation method thereof.

[0030] Example 1

[0031] The fluid loss reducer of this embodiment comprises the following raw materials in parts by weight: 10 parts of maleic anhydride, 0.1 parts of initiator (azobisisobutyronitrile), 0.8 parts of long-chain α-olefin (1-hexene), 30 parts of solvent (butyl acetate), and 5 parts of isobutylene.

[0032] The fluid loss reducer of this embodiment is prepared by the following steps:

[0033] 10 parts of maleic anhydride, 0.1 parts of azobisisobutyronitrile, 0.8 parts of 1-hexene and 30 parts of butyl acetate were added to a stainless steel reactor in sequence, stirred and dissolved, and 5 parts of isobutylene was added after nitrogen replacement 3 times, and the temperature was raised to 60°C and reacted for 5 hours;

[0034] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed at 75° C. to obtain the filtrate reducer.

[0035] Example 2

[0036] The fluid loss reducer of this embodiment includes the following raw materials in parts by weight: 10 parts of maleic anhydride, 0.4 parts of initiator (0.2 parts of azobisisoheptylnitrile and 0.2 parts of azobisisobutyronitrile), 4.5 parts of long-chain α-olefin (1-hexadecene), 40 parts of solvent (isoamyl acetate), and 4.5 parts of isobutylene.

[0037] The fluid loss reducer of this embodiment is prepared by the following steps:

[0038] 10 parts of maleic anhydride, 0.2 parts of azobisisoheptanonitrile, 0.2 parts of azobisisobutyronitrile, 4.5 parts of 1-hexadecene, and 40 parts of isoamyl acetate were added to a stainless steel reactor in sequence, stirred and dissolved, and 4.5 parts of isobutylene was added after nitrogen replacement 3 times, and the temperature was raised to 50°C and reacted for 6 hours;

[0039] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed to obtain the filtrate reducer.

[0040] Example 3

[0041] The fluid loss reducer of this embodiment comprises the following raw materials in parts by weight: 10 parts of maleic anhydride, 0.2 parts of initiator (azobisisobutyronitrile), 18 parts of long-chain α-olefin (1-hexadecene), 50 parts of solvent (butyl acetate), and 1 part of isobutylene.

[0042] The fluid loss reducer of this embodiment is prepared by the following steps:

[0043] 10 parts of maleic anhydride, 0.2 parts of azobisisobutyronitrile, 18 parts of 1-hexadecene, and 50 parts of butyl acetate were sequentially added to a stainless steel reactor and stirred to dissolve. After argon replacement three times, 1 part of isobutylene was added, and the temperature was raised to 70°C and reacted for 4 hours.

[0044] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed to obtain the filtrate reducer.

[0045] The infrared spectrum of the fluid loss reducer prepared in this example is as follows: Figure 1 shown.

[0046] Example 4

[0047] The fluid loss reducer of this embodiment includes the following raw materials in parts by weight: 10 parts of maleic anhydride, 3.7 parts of initiator (dibenzoyl peroxide), 27 parts of long-chain α-olefin (1-nonadecene), 60 parts of solvent (15 parts of ethyl acetate, 45 parts of toluene), and 0 parts of isobutylene.

[0048] 10 parts of maleic anhydride, 3.7 parts of dibenzoyl peroxide, 27 parts of 1-nonadecene, 15 parts of ethyl acetate and 45 parts of toluene were sequentially added into a stainless steel reactor and stirred to dissolve. After nitrogen replacement 3 times, the temperature was raised to 80°C and reacted for 3 hours.

[0049] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed to obtain the filtrate reducer.

[0050] According to the constituent raw materials and preparation method of the fluid loss reducer of the present invention, the inventors obtained the following comparative examples by adjusting the dosage of some raw materials, which are given as comparative examples 1 to 2.

[0051] Comparative Example 1

[0052] The filtrate reducer of this comparative example comprises the following raw materials in parts by weight: 10 parts of maleic anhydride, 0.2 parts of initiator (azobisisobutyronitrile), 2 parts of long-chain α-olefin (1-hexadecene), 50 parts of solvent (butyl acetate), and 7 parts of isobutylene.

[0053] 10 parts of maleic anhydride, 0.2 parts of azobisisobutyronitrile, 2 parts of 1-hexadecene, and 50 parts of butyl acetate were sequentially added to a stainless steel reactor and stirred to dissolve. After argon replacement three times, 7 parts of isobutylene was added, and the temperature was raised to 70°C and reacted for 4 hours.

[0054] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed to obtain the filtrate reducer.

[0055] Comparative Example 2

[0056] The filtrate reducer of this comparative example comprises the following raw materials in parts by weight: 10 parts of maleic anhydride, 5 parts of initiator (azobisisoheptylnitrile), 4.5 parts of long-chain α-olefin (1-hexadecene), 40 parts of solvent (isoamyl acetate), and 4.5 parts of isobutylene.

[0057] 10 parts of maleic anhydride, 5 parts of azobisisoheptanonitrile, 4.5 parts of 1-hexadecene and 40 parts of isoamyl acetate were sequentially added into a stainless steel reactor and stirred to dissolve. After nitrogen replacement for 3 times, 4.5 parts of isobutylene was added, and the temperature was raised to 50°C and reacted for 6 hours.

[0058] After the reaction liquid is cooled to room temperature, it is slowly poured into n-hexane to precipitate solids, the product is filtered and washed, and the washed product is dried and crushed to obtain the filtrate reducer.

[0059] The fluid loss reducers prepared in the above Examples 1 to 4 and Comparative Examples 1 to 2 are applied to the oil-based drilling process to prepare drilling fluids. According to the conventional drilling fluid preparation method in the industry, Application Examples 1 to 4 and Comparative Examples 1 to 2 are given.

[0060] Application Example 1

[0061] The drilling fluid in this application example includes the following components by weight: 80 parts of gas-to-oil

[0062] (185V)+20 parts CaCl 2 Aqueous solution (mass concentration is 20%) + 3 parts of primary emulsifier (DR-EM) + 2 parts of auxiliary emulsifier (DR-CO) + 2 parts of organic soil (HF-120) + 4 parts of fluid loss reducer (Example 1) + 2 parts of calcium oxide + 300 parts of barite.

[0063] Application Example 2

[0064] The difference from Application Example 1 is that the fluid loss reducer prepared in Example 2 is used instead of the fluid loss reducer in Application Example 1.

[0065] Application Example 3

[0066] The difference from Application Example 1 is that the fluid loss reducer prepared in Example 3 is used instead of the fluid loss reducer in Application Example 1.

[0067] Application Example 4

[0068] The difference from Application Example 1 is that the fluid loss reducer prepared in Example 4 is used instead of the fluid loss reducer in Application Example 1.

[0069] Application Comparative Example 1

[0070] The difference from Application Example 1 is that the filtrate reducer prepared in Comparative Example 1 is used instead of the filtrate reducer in Application Example 1.

[0071] Application Comparative Example 2

[0072] The difference from Application Example 1 is that the filtrate reducer prepared in Comparative Example 2 is used instead of the filtrate reducer in Application Example 1.

[0073] In addition, other types of fluid loss reducers used in actual application are taken as comparative application examples of the present invention, and comparative application examples 3 to 4 are given.

[0074] Application Comparative Example 3

[0075] The drilling fluid of this comparative example includes the following components by weight: 80 parts of gas-to-liquid (185V) + 20 parts of CaCl 2 Aqueous solution (mass concentration is 20%) + 3 parts of primary emulsifier (DR-EM) + 2 parts of auxiliary emulsifier (DR-CO) + 2 parts of organic soil (HF-120) + 4 parts of fluid loss reducer - asphalt + 2 parts of calcium oxide + 300 parts of barite.

[0076] Application Comparative Example 4

[0077] The drilling fluid of this comparative example includes the following components by weight: 80 parts of gas-to-liquid (185V) + 20 parts of CaCl 2 Aqueous solution (mass concentration is 20%) + 3 parts of primary emulsifier (DR-EM) + 2 parts of auxiliary emulsifier (DR-CO) + 2 parts of organic soil (HF-120) + 4 parts of fluid loss reducer - humic acid amine + 2 parts of calcium oxide + 300 parts of barite.

[0078] The above application examples 1 to 4 and application comparison examples 1 to 4 were subjected to the following performance tests. According to the relevant methods described in the national standard GB / T16783.2 "Field Test of Drilling Fluids in the Petroleum and Natural Gas Industry", the test results were recorded in Table 2 below.

[0079] Table 2: Drilling fluid performance evaluation results

[0080]

[0081] Combining the above experiments with the experimental results in Table 2, it can be seen that Application Comparative Example 3 and Application Comparative Example 4 are gas-to-oil synthetic-based drilling fluid systems prepared with asphalt-based fluid loss reducers and humic acid amine-based fluid loss reducers, respectively. After high-temperature aging at 220°C, the high-temperature and high-pressure fluid loss of the synthetic-based drilling fluid system of Application Comparative Example 3 was 12.4 ml. The fluid loss was too large, which could easily cause accidents such as well wall instability and collapse. Therefore, the asphalt-based fluid loss reducer cannot be used as a fluid loss reducer for the gas-to-oil synthetic-based drilling fluid system with a temperature resistance of 220°C. After high-temperature aging at 220°C, the high-temperature and high-pressure fluid loss of the synthetic-based drilling fluid system of Application Comparative Example 4 was 8.2 ml, which was better than the asphalt-based fluid loss reducer, and the demulsification voltage of 1012V was better than the asphalt-based fluid loss reducer drilling fluid system of 617V, indicating that the fluid loss performance of the humic acid amine-based fluid loss reducer under high-temperature conditions of 220°C is better than that of the asphalt-based fluid loss reducer product. However, the high-temperature and high-pressure filtration loss of 8.2 ml is too large, which is also easy to cause wellbore instability. Therefore, it cannot be directly used as a filtration loss reducer for 220℃ high-temperature gas-to-oil synthetic-based drilling fluid system.

[0082] The polymer fluid loss reducer prepared by Examples 1-4 of the present invention is formulated into a gas-to-oil synthetic-based drilling fluid system, and the high-temperature and high-pressure fluid loss of the gas-to-oil synthetic-based drilling fluid system after aging at 220°C is in the range of 2.4 to 2.8 ml, indicating that the polymer fluid loss reducer of the present patent has excellent high-temperature and high-pressure fluid loss performance, and meets the technical requirements of high-temperature and high-pressure fluid loss performance of a 220°C high-temperature gas-to-oil synthetic-based drilling fluid system. The demulsification voltage of the gas-to-oil synthetic-based drilling fluid system of Examples 1-4 of the invention is above 1154V, which is much higher than the 400V required at the drilling construction site, indicating that the polymer fluid loss reducer of the present invention is beneficial to the electrical stability of the synthetic-based drilling fluid system. The polymer fluid loss reducer of the present invention effectively solves the problem of large high-temperature and high-pressure fluid loss of a 220°C high-temperature gas-to-oil synthetic-based drilling fluid system.

[0083] The high-temperature and high-pressure filtration losses of the gas-to-liquid synthetic-based drilling fluid prepared with the high-molecular polymer filtration reducer prepared in Comparative Examples 1 to 2 were 4.6 ml and 5.3 ml, respectively. The filtration loss performance was significantly better than the high-temperature and high-pressure filtration loss performance of the gas-to-liquid synthetic-based drilling fluid prepared with the asphalt filtration reducer and the humic acid amine filtration reducer, and was lower than the high-temperature and high-pressure filtration loss performance of the high-molecular polymer filtration reducer prepared in Examples 1 to 4.

[0084] The above are only preferred feasible embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Various modifications or applications made according to the above embodiments are within the protection scope of this technical solution.

[0085] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. High temperature resistant fluid loss reducer, characterized in that: The raw material composition includes the following by weight: 10 parts of maleic anhydride, 0-5 parts of isobutylene, 0.8-27 parts of long-chain alpha-olefin, and 0.1-3.7 parts of initiator.

2. The high temperature resistant fluid loss reducer according to claim 1, characterized in that: The filtrate reducer also includes 30 to 60 parts of solvent.

3. The high temperature resistant fluid loss reducer according to claim 2, characterized in that: The solvent is selected from organic acid alkyl esters and / or aromatic hydrocarbons.

4. The high temperature resistant fluid loss reducer according to claim 1, characterized in that: The long-chain α-olefin is selected from α-olefins having 6 to 19 carbon atoms.

5. The high temperature resistant fluid loss reducer according to claim 1, characterized in that: The initiator is a thermal decomposition type initiator.

6. The high temperature resistant fluid loss reducer according to claim 5, characterized in that: The thermal decomposition initiator is selected from one or more of dibenzoyl peroxide, diisopropyl peroxide, di-tert-butyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicarbonyl peroxide, azobisisobutyronitrile, azobisisovaleronitrile and azobisisoheptonitrile.

7. A method for preparing the high temperature resistant fluid loss reducer according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1, add maleic anhydride, initiator, long-chain α-olefin and solvent in sequence, stir to dissolve, add isobutylene, and heat to react; S2, after cooling the reaction solution of S1 to room temperature, pour it into n-hexane to precipitate solid; S3, filtering and washing the solid precipitated in S2, drying and crushing the washed solid to obtain a filtrate reducer.

8. The method for preparing the high temperature resistant fluid loss reducer according to claim 7, characterized in that: In S1, the inert gas is selected from one or more of nitrogen, helium and argon.

9. The method for preparing the high temperature resistant fluid loss reducer according to claim 7, characterized in that: In the step S1, the reaction temperature is 50-80° C. and the reaction time is 3-6 hours.

10. Use of the high temperature resistant fluid loss reducer according to any one of claims 1 to 9 in a gas-to-liquid synthetic-based drilling fluid.

11. A gas-to-liquid synthetic-based drilling fluid, characterized in that: The gas-to-liquid synthetic-based drilling fluid contains the high-temperature resistant fluid loss reducer as claimed in claim 10.

12. An oilfield drilling process, characterized in that: The drilling process uses the gas-to-liquid synthetic-based drilling fluid as described in claim 11.

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