High-temperature-resistant filtrate reducer, high-temperature-resistant desulfonation oil-in-water drilling fluid and preparation method

Abstract

The invention discloses a high-temperature-resistant filtrate reducer, a high-temperature-resistant desulfonation oil-in-water drilling fluid and a preparation method, belongs to the technical field of drilling fluids, and solves the problem of poor environmental protection property of the existing drilling fluid. The high-temperature-resistant filtrate reducer comprises an alternating biopolymer and salt-resistant grade-layer chain silicate clay minerals, and the alternating biopolymer is obtained after itaconic acid and allyl phenyl sulfone are subjected to free radical polymerization reaction. The high-temperature-resistant filtrate reducer is a compound of an alternating bipolymer and salt-resistant layer chain silicate clay minerals, replaces traditional sulfonated lignite, sulfonated resin, oxidized asphalt and other sulfonated materials, and can enable a drilling fluid system to realize excellent properties of high temperature resistance and extremely low filtration loss while desulfonating.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling fluids, and more particularly to a high-temperature resistant fluid loss reducer, a high-temperature resistant desulfonated oil-in-water drilling fluid, and a preparation method thereof. Background Art

[0002] Oil-in-water drilling fluid is a special type of drilling fluid, which uses water as the continuous phase, oil as the dispersed phase, and a certain amount of surfactant is added. This drilling fluid not only retains the advantages of water-based drilling fluids but also has the characteristics of oil-based drilling fluids. It has strong sand-carrying capacity, excellent lubricating performance, low friction, and is not likely to cause wellbore shrinkage and formation collapse in complex formations. In addition, its low water loss can effectively reduce the damage of the drilling fluid to the oil and gas layers. Therefore, oil-in-water drilling fluids are widely used in low-pressure formation wells, underbalanced wells, horizontal wells, and extended reach wells.

[0003] The prior art provides various oil-in-water drilling fluid technologies, but the components of these drilling fluids contain sulfonated materials. Although sulfonated materials have excellent high-temperature resistance and fluid loss reduction properties, they also bring environmental problems and have an adverse impact on the environment. For example, Patent CN104610944A discloses an oil-in-water drilling fluid using vegetable oil as the internal phase and its preparation method. The density range of this drilling fluid is 0.89 - 0.99 g / cm 3 , and it can withstand a high-temperature environment of up to 170°C, but its fluid loss reducer still selects sulfonated materials, bringing certain environmental impacts.

[0004] To ensure the smooth progress of drilling operations, most drilling fluids need to be prepared in advance. However, there are some potential disadvantages in preparing drilling fluids in advance: after the drilling fluid is prepared, its performance may change over time; the pre-prepared drilling fluid needs to be properly stored and maintained, which may require additional equipment and manpower investment, thus increasing the maintenance cost; and the pre-prepared drilling fluid cannot be quickly prepared according to the on-site situation, resulting in poor pertinence; the drilling fluid contains various chemical components, and if stored improperly or leaks, it may pollute the environment and even pose a threat to personnel safety.

[0005] Therefore, there is an urgent need to study an oil-in-water drilling fluid with high-temperature resistance, environmental friendliness, and a simple preparation process. Summary of the Invention

[0006] In view of the above defects, the present invention provides a high-temperature resistant fluid loss reducer, a high-temperature resistant desulfonated oil-in-water drilling fluid, and a preparation method thereof. This high-temperature resistant fluid loss reducer replaces traditional sulfonated materials such as sulfonated lignite, sulfonated resin, and oxidized asphalt, and the system achieves excellent high-temperature resistance and extremely low fluid loss while being desulfonated.

[0007] In a first aspect, the present invention provides a high-temperature resistant fluid loss reducer, which comprises an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral. Among them, the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allyl phenyl sulfone.

[0008] Preferably, the principle of the free radical polymerization reaction is as follows:

[0009] In a second aspect, the present invention also provides a preparation method of the above high-temperature resistant fluid loss reducer. The preparation method comprises the following steps: S11, dissolve itaconic acid and allyl phenyl sulfone in deionized water, adjust the pH to 6-7, and add ammonium persulfate as an initiator under nitrogen protection for free radical polymerization reaction; S12, after the free radical polymerization reaction is completed, quickly pour the reaction product into absolute ethanol, perform suction filtration to obtain a precipitate, and wash and dry the precipitate to obtain a white solid, which is the alternating binary copolymer; S13, mix the alternating binary copolymer with the salt-resistant layered chain silicate clay mineral to obtain the high-temperature resistant fluid loss reducer.

[0010] Preferably, the mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:1.

[0011] Preferably, the temperature of the free radical polymerization reaction is 60-80°C and the time is 6-10h.

[0012] Preferably, the mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:1.

[0013] In a third aspect, the present invention also provides a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, which comprises the above high-temperature resistant fluid loss reducer, and also comprises fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant oil-in-water main emulsifier, auxiliary emulsifier, viscosifier, plugging agent and barite. Among them, bentonite and viscosifier can be added alternatively or simultaneously.

[0014] Preferably, based on the total volume of fresh water and base oil, the content of fresh water is 70-90%, and the content of base oil is 10-30%; the mass (g) to volume (ml) ratios of other components in the drilling fluid to the total volume of fresh water and base oil are respectively: 0%-1% bentonite, 0.1%-0.3% alkalinity regulator, 2%-4% high-temperature resistant oil-in-water main emulsifier, 0%-2% auxiliary emulsifier, 0%-1% viscosifier, 0.5%-2% high-temperature resistant fluid loss reducer, 1%-2% plugging agent, and the content of barite is determined according to the target density of the drilling fluid.

[0015] Preferably, the alkalinity regulator is caustic soda; the high-temperature resistant water-in-oil main emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate; the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate; the viscosifier is a high-temperature resistant monomer macromolecule xanthan gum; the plugging agent is calcium carbonate particles with a particle size of 5 microns.

[0016] Fourthly, the present invention also provides a method for preparing the above-mentioned high-temperature resistant desulfonated environmentally friendly water-in-oil drilling fluid, and the method includes the following steps: S21, mix bentonite and fresh water to obtain a bentonite slurry, place the bentonite slurry and the alkalinity regulator on a high-speed stirrer, stir at a high speed for 5 - 10 min, and then add the viscosifier and stir at a high speed for 5 - 10 min; S22, add a filtrate reducer and stir at a high speed for 5 - 10 min; S23, add the main emulsifier and the auxiliary emulsifier, stir at a high speed for 5 - 10 min; add the oil phase and stir at a high speed for 10 min; S24, add the plugging agent and stir at a high speed for 5 - 10 min; S25, add barite and stir at a high speed for more than 30 min to obtain a high-temperature resistant desulfonated environmentally friendly water-in-oil drilling fluid.

[0017] The beneficial effects of the present invention are as follows: The high-temperature resistant filtrate reducer of the present invention is a composite of an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral. Among them, the alternating binary copolymer is obtained by free radical polymerization of itaconic acid (IA) and allyl phenyl sulfone, replacing traditional sulfonated materials such as sulfonated lignite, sulfonated resin, and oxidized asphalt. The system realizes excellent properties of high temperature resistance and extremely low filtration loss while desulfonating. Description of the Drawings

[0018] Figure 1 are the photos before and after the compounding of the alternating binary copolymer and the salt-resistant layered chain silicate clay mineral in Example 1; Figure 2 is the schematic diagram of the glass rod test points in the test example. Detailed Embodiments

[0019] The following specifically describes the detailed embodiments of the present invention.

[0020] It should be noted that the "sulfonation" in the present invention refers to sulfonated components such as sulfonated lignite, sulfonated asphalt, sulfonated phenolic resin, sulfonated tannin, and sulfonated tannin extract used in the prior art. As long as the drilling fluid uses these materials, it is a sulfonated system; the "desulfonation" of the present invention means that the above sulfonated components are not included.

[0021] In a first aspect, the present invention provides a high-temperature resistant fluid loss reducer, which comprises an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral. Among them, the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allyl phenyl sulfone.

[0022] It should be noted that the principle of the free radical polymerization reaction is as follows:

[0023] The high-temperature resistant fluid loss reducer of the present invention is a composite of an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral. Among them, the alternating binary copolymer is obtained by free radical polymerization of itaconic acid (IA) and allyl phenyl sulfone, replacing traditional sulfonated materials such as sulfonated lignite, sulfonated resin, and oxidized asphalt. The system realizes excellent properties of high-temperature resistance and extremely low fluid loss while desulfonating. Specifically, the two carboxyl groups (-COOH) in itaconic acid (HOOC-CH=CH-COOH) are connected on both sides of the carbon-carbon double bond (C=C). The carbon-carbon double bond (C=C) on the molecular chain has high thermal stability and is an active site that can participate in the polymerization reaction, and can copolymerize with various monomers containing unsaturated bonds; the carboxyl group increases the hydration ability of the polymer after polymerization, improving the fluid loss reducing performance and stability of the drilling fluid. Allyl phenyl sulfone (Ph-SO2-CH2-CH=CH2), where Ph represents phenyl (C6H5-), also has a carbon-carbon double bond (C=C) for initiating the polymerization reaction and a sulfone group (-SO2) with high thermal stability, which can copolymerize with itaconic acid to form a high-temperature resistant alternating copolymer. The polymer formed by polymerization is a repeating chain shape and is not easily broken at high temperatures.

[0024] The principle of the free radical polymerization reaction is specifically as follows: The initiator decomposes under heat to generate free radicals, and the free radicals attack the carbon-carbon double bond of the monomer to initiate a chain growth reaction. The two monomers are randomly incorporated into the growing chain according to factors such as their respective concentrations and activities, gradually forming an alternating binary copolymer with different chain segment structures and lengths.

[0025] Exemplarily, the salt-resistant layered chain silicate clay mineral is at least one of halloysite, attapulgite, and kaolinite.

[0026] Exemplarily, the mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:1, preferably 2:1.

[0027] Exemplarily, the mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:1, preferably 9:1.

[0028] In a second aspect, the present invention also provides a preparation method of the above high-temperature resistant fluid loss reducer, and the preparation method comprises the following steps: S11. Dissolve itaconic acid and allyl phenyl sulfone in deionized water, adjust the pH to 6 - 7, and add ammonium persulfate as the initiator under nitrogen protection for free radical polymerization reaction. S12. After the free radical polymerization reaction ends, quickly pour the reaction product into absolute ethanol, perform suction filtration to obtain a precipitate, and wash and dry the precipitate to obtain a white solid, which is the alternating binary copolymer. S13. Mix the alternating binary copolymer with a salt - resistant layered silicate clay mineral to obtain a high - temperature filtration loss reducer.

[0029] In the present invention, the initiator decomposes to generate free radicals, and the free radicals attack the carbon - carbon double bond of the monomer to initiate a chain - growth reaction. The two monomers, itaconic acid and allyl phenyl sulfone, are randomly incorporated into the growing chain according to factors such as their respective concentrations and activities, gradually forming an alternating binary copolymer with different chain - segment structures and lengths. Then, quickly pour the reaction product into absolute ethanol, which can precipitate the alternating binary copolymer to form a precipitate. Through suction filtration, washing, drying, etc., the precipitate forms a white solid alternating binary copolymer.

[0030] Exemplarily, in step S11, the mass ratio of itaconic acid to allyl phenyl sulfone is 1 - 3:1, preferably 2:1, and the high - temperature resistance performance is the best within this preferred range.

[0031] Exemplarily, in step S11, the temperature of the free radical polymerization reaction is 60 - 80 °C, and the time is 6 - 10 h. When the reaction temperature ≥ 75 °C, the reaction proceeds more thoroughly, and the amount of by - reactants and residues is the least. Therefore, the temperature of the free radical polymerization reaction is preferably 75 - 80 °C; when the reaction time is 6 - 10 h, the monomer activity is in the best state during this period, the reaction is stable and controllable, and the polymerization reaction proceeds fully and thoroughly.

[0032] Exemplarily, step S11 specifically includes: install a three - necked flask in a constant - temperature water bath, install a stirrer in the middle, and install a condenser and a thermometer on both sides; fill the three - necked flask with deionized water and stir, then sequentially add purified itaconic acid and allyl phenyl sulfone and stir until fully dissolved to obtain a monomer solution; add analytical - grade NaOH to the monomer solution to adjust the pH value of the solution to 6 - 7 to make the solution neutral; add ammonium persulfate as the initiator under nitrogen protection, stir and maintain the temperature at 60 - 80 °C, and continuously stir the solution for reaction for 6 - 10 h.

[0033] Exemplarily, the purity of both itaconic acid and allyl phenyl sulfone is above 98% to reduce the generation of impurities and accelerate the reaction activity.

[0034] Exemplarily, in the monomer solution, the mass concentration of itaconic acid is 17.5 - 18%, and the mass concentration of allyl phenyl sulfone is 12 - 13%.

[0035] Exemplarily, step S12 specifically includes: after the radical polymerization reaction ends, quickly pour the reaction product into anhydrous ethanol while it is still hot, perform suction filtration using a Buchner funnel, collect the precipitate, wash the precipitate repeatedly several times to remove residues and impurities completely, place the precipitate in an oven for drying, and obtain a white solid, which is the alternating binary copolymer.

[0036] Exemplarily, the mass ratio of the alternating binary copolymer to the anti-salt layer silicate clay mineral is 8 - 10:1, preferably 9:1.

[0037] In a third aspect, the present invention also provides a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, which includes the above-mentioned high-temperature resistant filtration reducer, and also includes fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant oil-in-water main emulsifier, auxiliary emulsifier, viscosifier, plugging agent, and barite. Among them, bentonite and the viscosifier can be added alternatively or simultaneously.

[0038] In the drilling fluid system of the present invention, a self-synthesized polymer filtration reducer is used to replace traditional sulfonated materials and part or all of the bentonite, which not only reduces the adverse impact on the environment but also reduces the thickening phenomenon of bentonite at high temperatures. For the scheme without bentonite, it truly achieves an environmentally friendly drilling fluid system without soil phase and without sulfonation.

[0039] Exemplarily, the base oil is at least one of white oil, diesel oil, and biodiesel.

[0040] Exemplarily, based on the total volume of fresh water and base oil, the content of fresh water is 70 - 90%, and the content of base oil is 10 - 30%; the mass (g) to volume (mL) ratios of other components in the drilling fluid to the total volume of fresh water and base oil are as follows: 0% - 1% bentonite (such as 0.5%, 1%), 0.1% - 0.3% alkalinity regulator, 2% - 4% high-temperature resistant oil-in-water main emulsifier, 0% - 2% auxiliary emulsifier (such as 1%, 2%), 0% - 1% viscosifier (such as 0.5%, 1%), 0.5% - 2% high-temperature resistant filtration reducer, 1% - 2% plugging agent, and the content of barite is determined according to the target density of the drilling fluid.

[0041] Exemplarily, the density of the high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid is 1.2 - 2.0 g / cm 3 。

[0042] Exemplarily, the bentonite is API standard bentonite.

[0043] Exemplarily, the alkalinity regulator is caustic soda, which is used to adjust the pH value of the drilling fluid.

[0044] Exemplarily, the high-temperature resistant oil-in-water main emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate. Specifically: the compound is prepared by compounding fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate at a ratio of 3:1 at 40°C. After thorough mixing and mutual dissolution by low-speed stirring, a main emulsifier with a high HLB value is obtained. The compounded main emulsifier has a synergistic effect in enhancing the emulsification and dispersion effects, etc.

[0045] Exemplarily, the auxiliary emulsifier is lipophilic nonionic surfactant sorbitan monooleate (SP80); due to the presence of hydrophilic hydroxyl groups, lipophilic oleic acid long-chain hydrocarbon groups and multiple ether bonds in its molecular structure, its own structure endows it with good amphiphilicity. As an auxiliary emulsifier, when compounded with a main emulsifier with a high HLB value, it can form a tightly structured composite interfacial film to enhance the emulsification effect.

[0046] Exemplarily, the viscosifier is high-temperature resistant monomer macromolecule xanthan gum (XC); its relatively low concentration can provide a high viscosity, which can effectively improve the viscosity and stability of the drilling fluid.

[0047] Exemplarily, the plugging agent is calcium carbonate particles with a particle size of 5 microns; it plays a role in plugging and bridging. When used in combination with a polymer filtration reducer, it can effectively reduce the filtration loss of the drilling fluid.

[0048] The high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid of the present invention has the following advantages: (1) Environmental protection: In this drilling fluid system, a self-synthesized polymer filtration reducer is used to replace traditional sulfonated materials and part or all of the bentonite. Bentonite can be added in trace amounts or not added at all, greatly reducing the use of filtration reducer materials. This not only reduces the adverse impact on the environment but also reduces the thickening phenomenon of bentonite at high temperatures. For the scheme without bentonite, a truly soil-free and sulfonation-free environmentally friendly drilling fluid system is achieved, meeting the current environmental protection requirements.

[0049] (2) High efficiency: The preparation process of this drilling fluid is simple, greatly shortening the preparation time in the laboratory and on-site, improving production efficiency and facilitating maintenance.

[0050] (3) Economy: The preparation cost of this drilling fluid is relatively low. Using the oil-in-water system means that only a small amount of oil phase is used in the system. It not only achieves the lubricity of oil-based drilling fluid but also takes into account the low cost of water-based drilling fluid. The preparation of a drilling fluid with a temperature resistance of 180°C can be completed only by using a small amount of core treatment agents, significantly reducing the use cost.

[0051] Fourthly, the present invention also provides a method for preparing the above-mentioned high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, and the method includes the following steps: S21. Mix bentonite and fresh water to obtain a bentonite slurry. Place the bentonite slurry and an alkalinity regulator on a high-speed stirrer and stir at a high speed for 5 - 10 minutes. Then add a viscosifier and stir at a high speed for 5 - 10 minutes. S22. Add a filtration reducer and stir at a high speed for 5 - 10 minutes. S23. Add a primary emulsifier and a secondary emulsifier and stir at a high speed for 5 - 10 minutes. Add an oil phase and stir at a high speed for 10 minutes. S24. Add a plugging agent and stir at a high speed for 5 - 10 minutes. S25. Add barite and stir at a high speed for more than 30 minutes to obtain a high-temperature-resistant desulfonated environmentally friendly oil-in-water drilling fluid.

[0052] The preparation method of the drilling fluid of the present invention is simple and efficient. Moreover, the oil-in-water system achieves both the lubricity of oil-based drilling fluids and the low cost of water-based drilling fluids.

[0053] In a preferred embodiment, the method includes the following steps: S21. Mix bentonite and fresh water to obtain a bentonite slurry. Place the bentonite slurry and an alkalinity regulator on a high-speed stirrer and stir at a high speed for 5 minutes. Then add a viscosifier and stir at a high speed for 5 minutes. S22. Add a filtration reducer and stir at a high speed for 5 - 10 minutes. S23. Add a primary emulsifier and a secondary emulsifier and stir at a high speed for 10 minutes. Add an oil phase and stir at a high speed for 10 minutes. S24. Add a plugging agent and stir at a high speed for 10 minutes. S25. Add barite and stir at a high speed for 35 minutes to obtain a high-temperature-resistant desulfonated environmentally friendly oil-in-water drilling fluid.

[0054] Exemplarily, in steps S21 - S25, the rotation speed of the high-speed stirring used is 11000 ± 300 rpm. Only when the stirring rate is high enough can the full reaction be ensured.

[0055] Hereinafter, the high-temperature-resistant filtration reducer and drilling fluid of the present invention will be described in detail through specific examples.

[0056] In the following examples, the bentonite comes from Shaker (Tianjin) Petroleum Technology Service Co., Ltd., the caustic soda comes from Shaker (Tianjin) Petroleum Technology Service Co., Ltd., the viscosifier monomer macromolecular xanthan gum (XC) comes from Shaker (Tianjin) Petroleum Technology Service Co., Ltd., and the calcium carbonate particles come from Shaker (Tianjin) Petroleum Technology Service Co., Ltd.

[0057] Example 1

[0058] This example provides a high-temperature-resistant filtration reducer and its preparation method, including: S11: Install a three-necked flask in a constant temperature water bath, maintain the temperature at 75 °C, install a stirrer in the middle, and install a condenser and a thermometer on both sides; fill the three-necked flask with deionized water and stir, then sequentially add purified itaconic acid and allyl phenyl sulfone and stir until fully dissolved to obtain a monomer solution (the mass concentration of itaconic acid is 17.5%, and the mass concentration of allyl phenyl sulfone is 12%), and the mass ratio of itaconic acid to allyl phenyl sulfone is 2:1; add analytical pure NaOH to the monomer solution to adjust the pH value of the solution to 6-7 to make the solution neutral; add initiator ammonium persulfate under nitrogen protection and stir, and continuously stir the solution for reaction for 7 h.

[0059] S12: After the free radical polymerization reaction is completed, quickly pour the reaction product into anhydrous ethanol while it is hot, perform suction filtration operation using a Buchner funnel, collect the precipitate, wash the precipitate repeatedly many times to remove the residue and impurities completely, and place the precipitate in a drying oven for drying to obtain a white solid, which is the alternating binary copolymer.

[0060] S13, Mix the alternating binary copolymer with the anti-salt layer silicate clay mineral halloysite in a mass ratio of 9:1 evenly to obtain a high-temperature resistant filtration reducer, as Figure 1 shown.

[0061] Example 2

[0062] This example provides a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid and its preparation method, including: weighing 196 ml of bentonite slurry with a concentration of 0.5% using a high-speed stirring cup, adding 0.5 ppb of caustic soda and placing it on a high-speed stirrer, and using the 12000 rpm gear to stir at high speed for 5 min; adding 4 ppb of the high-temperature resistant filtration reducer prepared in Example 1 and stirring at high speed for 5 min using 12000 rpm; adding 8 ppb of the main emulsifier and 4 ppb of the auxiliary emulsifier, and stirring at high speed for 10 min using 12000 rpm; adding 84 ml of No. 3 white oil and stirring at high speed for 10 min using 12000 rpm; adding 7 ppb of calcium carbonate particles with a particle size of 5 microns and stirring at high speed for 10 min using 12000 rpm; adding barite with a designed density and stirring at high speed for 35 min using 12000 rpm to obtain an oil-in-water drilling fluid sample containing 30% oil.

[0063] Among them, the main emulsifier is a compound of fatty alcohol polyoxyethylene ether (AEO) and sodium dodecyl benzene sulfonate (LAS). The two emulsifiers are compounded at a ratio of 3:1 at 40 °C, and a high HLB value emulsifier is obtained after fully mixing and dissolving by low-speed stirring; the auxiliary emulsifier is a lipophilic non-ionic surfactant sorbitan monooleate (SP80).

[0064] Example 3

[0065] This embodiment provides a soil-free high-temperature resistant and desulfurized environmentally friendly oil-in-water drilling fluid and its preparation method.

[0066] Weigh 196 ml of fresh water using a high-speed stirring cup, add 0.5 ppb of caustic soda and place it on a high-speed stirrer. Stir at a high speed of 12,000 rpm for 5 minutes; add 4 ppb of the thickening agent monomer xanthan gum (XC), and stir at 12,000 rpm for 5 minutes; add 4 ppb of the high-temperature resistant filtration reducer prepared in Example 1, and stir at 12,000 rpm for 5 minutes; add 15 ppb of the main emulsifier, and stir at 12,000 rpm for 10 minutes; add 84 ml of No. 3 white oil, and stir at 12,000 rpm for 10 minutes; add 10 ppb of calcium carbonate particles with a particle size of 5 microns, and stir at 12,000 rpm for 10 minutes; add barite with the designed density, and stir at 12,000 rpm for 35 minutes to obtain an oil-in-water drilling fluid sample containing 30% oil.

[0067] The product is tested through two indicators, and Test Examples 1 and 2 are respectively adopted.

[0068] Test Example 1 Test the rheological properties and thermal stability of the drilling fluids in the above Examples 2-3. The specific test methods are as follows: Take out the drilling fluid in the aging kettle to a high-speed stirring cup and stir at 12,000 rpm for 10 minutes. Use Fann35 or its similar product to test the rheological properties of the stirred drilling fluid. Transfer the tested drilling fluid to the specified scale line in the aging kettle; keep it at a constant temperature and roll for 16 hours under the set bottom hole temperature condition; when the rolling time ends, take it out, naturally cool it to room temperature and then open it; place a glass rod with a diameter of 0.5 cm and a length of 30 cm at a position 2 cm above the tank surface and let it fall freely at the Figure 2 indicated test points to judge the state of the drilling fluid.

[0069] The judgment criteria for the state of the drilling fluid are as follows: (1) When the impact sound when the glass rod touches the bottom of the aging kettle can be heard, it bounces quickly, adheres to the wall quickly, pour out the sample in the kettle, and the flow pattern shows a continuous and uninterrupted linear flow. If there is no hard precipitation at the bottom of the kettle observed with the naked eye, it indicates that the drilling fluid has not settled.

[0070] (2) If the impact sound when the glass rod touches the bottom of the aging kettle cannot be heard or is faintly heard, it does not adhere to the wall or adheres to the wall slowly, pour out the sample in the tank, and the flow pattern is discontinuous and has blocky outflows. If there is hard precipitation at the bottom of the kettle observed with the naked eye, it indicates that the drilling fluid has settled. Determine the settlement degree based on the amount of hard precipitation at the bottom. If the soft precipitation at the bottom exceeds 1 cm or there is hard precipitation, the thermal stability of the drilling fluid is poor, which is not conducive to on-site operations.

[0071] Test Example 2 The filtration loss of the drilling fluids in the above Examples 2 - 3 was tested. The specific test method is as follows: Use a Fann HT 4700 filtration loss instrument to measure the filtration loss of the drilling fluid and observe the state of the filter cake. The criteria for judging the filtration loss of the drilling fluid and the filter cake are as follows: (1) The filtration loss of the drilling fluid in 30 minutes should be less than 10 ml; (2) The thickness of the filter cake should be less than 3 mm, and it should present a thin, smooth, dense, and tough state.

[0072] (3) If the filtration loss exceeds 10 ml, and the filter cake is porous, thick, not smooth, not dense, and has no toughness, then the thermal stability of the drilling fluid is poor, which is not conducive to on-site operations.

[0073] The test results of Example 2 are shown in Tables 1 and 2.

[0074] (1) The rheological properties of the drilling fluid after aging at 140 °C for 16 h are shown in Table 1 as follows:

[0075] Note: 600, 300, 200, 100, 6, 3, all correspond to the rotations of a six-speed viscometer. For example: The parameter corresponding to 600 is the reading at 600 rotations; the initial shear stress is the gel strength at 10 seconds: the minimum shear stress required to break the gel structure after the drilling fluid has been stationary for 10 seconds, which is also a reading; the final shear stress is the gel strength at 10 minutes: the minimum shear stress required to break the gel structure after being stationary for 10 minutes, which is also a reading; PV is the plastic viscosity, which reflects the intensity of the internal frictional force between solid particles and between solid and liquid phases in the drilling fluid under laminar flow conditions. It is 600 - 300 value; YP is the dynamic shear stress (yield value), which is the minimum shear stress for the drilling fluid to form a dynamic network structure under laminar flow conditions and represents the suspension ability. It is 0.511×(2× 300 - 600) value; FL HTHP is the high-temperature and high-pressure filtration loss, representing the plugging ability of the drilling fluid; FC is the thickness of the filter cake after high-temperature and high-pressure filtration.

[0076] (2) The rheological properties of the drilling fluid after aging at 180 °C for 16 h are shown in Table 2 as follows:

[0077] As can be seen from Table 1 and Table 2, the density of the drilling fluid formula in this embodiment is 1.8 g / cm 3 , and it can resist high temperature up to 180°C. When the drilling fluid is hot rolled at 140°C for 16 h, while maintaining excellent initial and final shear forces of 8 / 8 Pa and a dynamic shear force of 26 Pa in the system, it also maintains a low plastic viscosity, only 58 mPa·s; when the drilling fluid is hot rolled at 180°C for 16 h, the system still maintains excellent shear forces and a low plastic viscosity, and the 180°C HTHP filtration loss is only 10 ml.

[0078] It can be seen that while this formula meets the requirements of on-site construction, it further reduces the adverse impact on the environment.

[0079] The test results of Example 3 are shown in Table 3 and Table 4.

[0080] (1) The rheological properties of the drilling fluid after aging at 140°C for 16 h are as shown in Table 3 below:

[0081] (2) The rheological properties of the drilling fluid after aging at 180°C for 16 h are as shown in Table 4 below:

[0082] As can be seen from Table 3 and Table 4, the density of this drilling fluid formula is 1.8 g / cm 3 , and it can resist high temperature up to 180°C. After removing bentonite from the drilling fluid, the overall viscosity of the drilling fluid decreases. Whether it is hot rolled at 140°C for 16 h or at 180°C for 16 h, the drilling fluid system still maintains excellent dynamic shear force and low plastic viscosity, and the 180°C HTHP filtration loss is only 10.8 ml.

[0083] It can be seen that while the drilling fluid formula of the present invention meets the requirements of on-site construction, it further reduces the adverse impact on the environment.

[0084] The embodiments of the present application are described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection scope of the present application.

Claims

1. A high-temperature resistant fluid loss reducer, characterized in that, The high-temperature resistant fluid loss reducer comprises an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral. Among them, the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allyl phenyl sulfone.

2. The high-temperature resistant fluid loss reducer according to claim 1, characterized in that, The principle of the free radical polymerization reaction is as follows: 。 3. A preparation method of a high-temperature resistant fluid loss reducer as described in claim 1 or 2, characterized in that, The preparation method comprises the following steps: S11, Dissolve itaconic acid and allyl phenyl sulfone in deionized water, adjust the pH to 6-7, and add ammonium persulfate as an initiator under nitrogen protection for free radical polymerization reaction. S12, After the free radical polymerization reaction is completed, quickly pour the reaction product into absolute ethanol, perform suction filtration to obtain a precipitate, and wash and dry the precipitate to obtain a white solid, which is the alternating binary copolymer. S13, Mix the alternating binary copolymer with the salt-resistant layered chain silicate clay mineral to obtain the high-temperature resistant fluid loss reducer.

4. The preparation method according to claim 3, wherein The mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:

1.

5. The preparation method according to claim 3, wherein, The temperature of the free radical polymerization reaction is 60-80 °C, and the time is 6-10 h.

6. The preparation method according to claim 3, characterized in that The mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:

1.

7. An environmentally friendly oil-in-water drilling fluid resistant to high temperature and desulfonation, characterized in that, It includes the high-temperature resistant fluid loss reducer described in claim 1 or 2, and also includes fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant water-in-oil main emulsifier, auxiliary emulsifier, viscosifier, plugging agent and barite. Among them, bentonite and viscosifier can be added alternatively or simultaneously.

8. The high-temperature resistant and desulfonated environmentally friendly oil-in-water drilling fluid according to claim 7, characterized in that, Based on the total volume of fresh water and base oil, the content of fresh water is 70-90%, and the content of base oil is 10-30%; the mass-volume ratios of other components in the drilling fluid to the total volume of fresh water and base oil are respectively: 0%-1% bentonite, 0.1%-0.3% alkalinity regulator, 2%-4% high-temperature resistant water-in-oil main emulsifier, 0%-2% auxiliary emulsifier, 0%-1% viscosifier, 0.5%-2% high-temperature resistant fluid loss reducer, 1%-2% plugging agent, and the content of barite is determined according to the target density of the drilling fluid.

9. The high-temperature resistant and desulfonated environmentally friendly oil-in-water drilling fluid according to claim 7, characterized in that, The alkalinity regulator is caustic soda; the high-temperature resistant water-in-oil main emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate; the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate; the viscosifier is a high-temperature resistant monomer macromolecule xanthan gum; the plugging agent is calcium carbonate particles with a particle size of 5 microns.

10. A method for preparing a high-temperature resistant and desulfonated environmentally friendly oil-in-water drilling fluid as described in any one of claims 7-9, characterized in that, The method comprises the following steps: S21, Mix bentonite and fresh water to obtain a bentonite slurry, place the bentonite slurry and the alkalinity regulator on a high-speed stirrer, stir at high speed for 5-10 min, and then add the viscosifier and stir at high speed for 5-10 min. S22, Add the fluid loss reducer and stir at high speed for 5-10 min. S23, Add the main emulsifier and the auxiliary emulsifier, stir at high speed for 5-10 min; add the oil phase and stir at high speed for 10 min. S24, Add the plugging agent and stir at high speed for 5-10 min. S25, Add barite and stir at high speed for more than 30 min to obtain a high-temperature resistant desulfonated environmentally friendly water-in-oil drilling fluid.

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