High-temperature resistant fluid loss reducer and high-temperature resistant desulfonated oil-in-water drilling fluid and preparation method thereof

Abstract

The present invention discloses a high-temperature resistant fluid loss reducer and a high-temperature resistant desulfonated oil-in-water drilling fluid and a preparation method, which belong to the technical field of drilling fluids and solve the problem of poor environmental protection of existing drilling fluids. The high-temperature resistant fluid loss reducer includes an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral, wherein the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allylphenyl sulfone. The high-temperature resistant fluid loss reducer is a composite of an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral, which replaces traditional sulfonated materials such as sulfonated lignite, sulfonated resin, and oxidized asphalt. It can enable the drilling fluid system to achieve excellent performance of high-temperature resistance and extremely low fluid loss while being desulfonated.

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 and 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 with water as the continuous phase and oil as the dispersed phase, along with a certain amount of surfactant. This drilling fluid combines the advantages of water-based drilling fluid with the properties of oil-based drilling fluid. It has strong sand-carrying capacity, excellent lubricity, low friction, and is less likely to cause wellbore shrinkage and formation collapse in complex formations. Furthermore, its low water loss effectively minimizes damage to oil and gas reservoirs. Therefore, oil-in-water drilling fluid is widely used in low-pressure formation wells, underbalanced wells, horizontal wells, and extended-reach wells.

[0003] The existing technology provides a variety of oil-in-water drilling fluid technologies, but these drilling fluids contain sulfonated materials as components. Although sulfonated materials have excellent temperature resistance and fluid loss reduction properties, they also bring environmental problems and have adverse effects 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 of this drilling fluid is in the range of 0.89-0.99 g / cm 3 , can withstand high temperature environments up to 170°C, but its filtrate reducer still uses sulfonated materials, which brings certain environmental impacts.

[0004] To ensure smooth drilling operations, most drilling fluids need to be prepared in advance. However, there are some potential drawbacks to pre-preparing drilling fluids: After preparation, the properties of the drilling fluid may change over time; pre-prepared drilling fluids require proper storage and maintenance, which may require additional equipment and manpower, increasing maintenance costs; and pre-prepared drilling fluids cannot be quickly prepared based on site conditions, resulting in poor targeting. Drilling fluids contain a variety of chemical components, which, if improperly stored or leaked, could pollute the environment and even pose a threat to personnel safety.

[0005] Therefore, there is an urgent need to develop an oil-in-water drilling fluid that is resistant to high temperatures, environmentally friendly, and has a simple preparation process. Summary of the Invention

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

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

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

[0009]

[0010] In a second aspect, the present invention further provides a method for preparing the above-mentioned high-temperature resistant fluid loss reducer, the preparation method comprising the following steps:

[0011] S11, dissolving itaconic acid and allylphenyl sulfone in deionized water, adjusting the pH to 6-7, and adding ammonium persulfate as an initiator under nitrogen protection to carry out a free radical polymerization reaction;

[0012] S12, after the free radical polymerization reaction is completed, the reaction product is quickly poured into anhydrous ethanol, filtered to obtain a precipitate, and the precipitate is washed and dried to obtain a white solid, which is an alternating binary copolymer;

[0013] S13, mixing the alternating binary copolymer with a salt-resistant layered chain silicate clay mineral to obtain a high-temperature resistant fluid loss reducer.

[0014] Preferably, the mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:1.

[0015] Preferably, the temperature of the free radical polymerization reaction is 60-80° C. and the time is 6-10 h.

[0016] Preferably, the mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:1.

[0017] In a third aspect, the present invention also provides a high-temperature resistant desulfonated environmentally friendly water-in-oil drilling fluid, comprising the above-mentioned high-temperature resistant fluid loss reducer, and also comprising fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant water-in-oil main emulsifier, auxiliary emulsifier, thickener, plugging agent and barite, wherein bentonite and thickener can be added selectively or simultaneously.

[0018] Preferably, based on the total volume of fresh water and base oil, the fresh water content is 70-90%, and the base oil content 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: 0%-1% bentonite, 0.1%-0.3% alkalinity regulator, 2%-4% high-temperature resistant oil-in-water primary emulsifier, 0%-2% secondary emulsifier, 0%-1% viscosity enhancer, 0.5%-2% high-temperature resistant fluid loss reducer, and 1%-2% plugging agent. The barite content is determined based on the target density of the drilling fluid.

[0019] Preferably, the alkalinity regulator is caustic soda; the high-temperature resistant oil-in-water main emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate; the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate; the viscosity enhancer is a high-temperature resistant monomer macromolecular xanthan gum; and the plugging agent is calcium carbonate particles with a particle size of 5 microns.

[0020] In a fourth aspect, the present invention further provides a method for preparing the above-mentioned high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, the method comprising the following steps:

[0021] S21, mixing bentonite and fresh water to obtain bentonite slurry, placing the bentonite slurry and alkalinity regulator on a high-speed stirrer, stirring at high speed for 5-10 minutes, and then adding a tackifier and stirring at high speed for 5-10 minutes;

[0022] S22, add filtrate reducer and stir at high speed for 5-10 minutes;

[0023] S23, add the primary emulsifier and the auxiliary emulsifier, and stir at high speed for 5-10 minutes; add the oil phase and stir at high speed for 10 minutes;

[0024] S24, add the plugging agent and stir at high speed for 5-10 minutes;

[0025] S25, adding barite and stirring at high speed for more than 30 minutes to obtain a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid.

[0026] The beneficial effects of the present invention are:

[0027] 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. The alternating binary copolymer is obtained by free radical polymerization of itaconic acid (IA) and allylphenyl sulfone, replacing traditional sulfonated materials such as sulfonated lignite, sulfonated resin, and oxidized asphalt. The system achieves excellent high-temperature resistance and extremely low fluid loss performance while removing the sulfonation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 These are photos before and after compounding the alternating binary copolymer of Example 1 and the salt-resistant layered chain silicate clay mineral;

[0029] Figure 2 This is a schematic diagram of the glass rod test points in the test example. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are described in detail below.

[0031] It should be noted that the "sulfonation" in the present invention refers to the sulfonated components such as sulfonated lignite, sulfonated asphalt, sulfonated phenolic resin, sulfonated tannin, and sulfonated tannin used in the prior art. As long as the drilling fluid uses these materials, it is a sulfonated system; the "desulfonation" in the present invention means that it does not contain the above-mentioned sulfonated components.

[0032] 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, wherein the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allylphenyl sulfone.

[0033] It should be noted that the principle of the free radical polymerization reaction is as follows:

[0034]

[0035] 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. The alternating binary copolymer is obtained through a free radical polymerization reaction between itaconic acid (IA) and allylphenyl sulfone, replacing traditional sulfonated materials such as sulfonated lignite, sulfonated resins, and oxidized asphalt. While removing the sulfonation, the system achieves excellent high-temperature resistance and extremely low fluid loss properties. Specifically, the two carboxyl groups (-COOH) in itaconic acid (HOOC-CH=CH-COOH) are connected on either side of a carbon-carbon double bond (C=C). The carbon-carbon double bond (C=C) on the molecular chain has high thermal stability and serves as an active site for polymerization reactions, enabling copolymerization with a variety of monomers containing unsaturated bonds. After polymerization, the carboxyl groups increase the polymer's hydration capacity, improving the fluid loss reduction 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 polymerization reactions and a sulfone group (-SO2) with high thermal stability. It can be copolymerized with itaconic acid to form a high-temperature resistant alternating copolymer. The polymer formed by polymerization is a repeating chain that is not easily broken at high temperatures.

[0036] The principle of free radical polymerization reaction is specifically as follows: the initiator decomposes under heat to produce free radicals, which attack the carbon-carbon double bonds of the monomers to initiate a chain growth reaction. The two monomers are randomly connected to the growing chain based on their respective concentrations, activities and other factors, gradually forming alternating binary copolymers with different chain segment structures and lengths.

[0037] Illustratively, the salt-resistant layered chain silicate clay mineral is at least one of halloysite, attapulgite and kaolinite.

[0038] Illustratively, the mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:1, preferably 2:1.

[0039] Illustratively, the mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:1, preferably 9:1.

[0040] In a second aspect, the present invention further provides a method for preparing the above-mentioned high-temperature resistant fluid loss additive, the preparation method comprising the following steps:

[0041] S11, dissolving itaconic acid and allylphenyl sulfone in deionized water, adjusting the pH to 6-7, and adding ammonium persulfate as an initiator under nitrogen protection to carry out a free radical polymerization reaction;

[0042] S12, after the free radical polymerization reaction is completed, the reaction product is quickly poured into anhydrous ethanol, filtered to obtain a precipitate, and the precipitate is washed and dried to obtain a white solid, which is an alternating binary copolymer;

[0043] S13, mixing the alternating binary copolymer with a salt-resistant layered chain silicate clay mineral to obtain a high-temperature resistant fluid loss reducer.

[0044] In the present invention, the initiator decomposes to generate free radicals, which attack the carbon-carbon double bonds of the monomers, triggering a chain propagation reaction. The two monomers, itaconic acid and allylphenylsulfone, are randomly incorporated into the propagating chain based on factors such as their concentration and activity, gradually forming an alternating binary copolymer with different segment structures and lengths. The reaction product is then rapidly poured into anhydrous ethanol to cause the alternating binary copolymer to precipitate. The precipitate is then filtered, washed, and dried to form a white solid alternating binary copolymer.

[0045] For example, in step S11, the mass ratio of itaconic acid to allylphenyl sulfone is 1-3:1, preferably 2:1. The temperature resistance is best within this preferred range.

[0046] For example, in step S11, the temperature of the free radical polymerization reaction is 60-80°C, and the reaction time is 6-10 hours. When the reaction temperature is ≥75°C, the reaction proceeds more thoroughly, with minimal side reactions and residues. Therefore, the temperature of the free radical polymerization reaction is preferably 75-80°C. When the reaction time is 6-10 hours, the monomer activity is at its best, the reaction is stable and controllable, and the polymerization reaction proceeds fully and thoroughly.

[0047] Exemplarily, step S11 specifically includes: installing a three-necked flask in a constant temperature water bath, installing a stirrer in the middle, and installing a condenser and a thermometer on both sides; adding deionized water into the three-necked flask and stirring, and then adding purified itaconic acid and allylphenyl sulfone in sequence and stirring until fully dissolved to obtain a monomer solution; adding analytical grade NaOH to the monomer solution to adjust the pH value of the solution to 6-7, so that the solution is neutral; adding an initiator ammonium persulfate under nitrogen protection and stirring while maintaining the temperature at 60-80°C, and the solution is continuously stirred for 6-10 hours.

[0048] Illustratively, the purity of itaconic acid and allylphenyl sulfone is above 98% to reduce the generation of impurities and accelerate the reaction activity.

[0049] For example, 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%.

[0050] Exemplarily, step S12 specifically includes: after the free radical polymerization reaction is completed, the reaction product is quickly poured into anhydrous ethanol while hot, and a Buchner funnel is used for suction filtration to collect the precipitate, and the precipitate is repeatedly washed multiple times to remove residues and impurities, and the precipitate is placed in a drying oven to dry to obtain a white solid, which is the alternating binary copolymer.

[0051] Illustratively, the mass ratio of the alternating binary copolymer to the salt-resistant layered chain silicate clay mineral is 8-10:1, preferably 9:1.

[0052] In a third aspect, the present invention also provides a high-temperature resistant desulfonated environmentally friendly water-in-oil drilling fluid, comprising the above-mentioned high-temperature resistant fluid loss reducer, and also comprising fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant water-in-oil main emulsifier, auxiliary emulsifier, thickener, plugging agent and barite, wherein bentonite and thickener can be added selectively or simultaneously.

[0053] The drilling fluid system of the present invention uses a self-synthesized polymer fluid loss reducer to replace traditional sulfonated materials and part or all of the bentonite, thereby reducing the adverse impact on the environment and reducing the thickening phenomenon of the bentonite under high temperature conditions. Compared with the solution without bentonite, a truly soil-phase-free and sulfonated environmentally friendly drilling fluid system is achieved.

[0054] Illustratively, the base oil is at least one of white oil, diesel and biodiesel.

[0055] For example, based on the total volume of fresh water and base oil, the fresh water content is 70-90%, and the base oil content 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: 0%-1% bentonite (e.g., 0.5%, 1%), 0.1%-0.3% alkalinity regulator, 2%-4% high-temperature resistant oil-in-water primary emulsifier, 0%-2% secondary emulsifier (e.g., 1%, 2%), 0%-1% viscosity enhancer (e.g., 0.5%, 1%), 0.5%-2% high-temperature resistant fluid loss reducer, 1%-2% plugging agent, and the barite content is determined according to the target density of the drilling fluid.

[0056] For example, the density of the high temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid is 1.2-2.0 g / cm 3 .

[0057] Exemplarily, the bentonite is API standard bentonite.

[0058] Exemplarily, the alkalinity regulator is caustic soda, which is used to adjust the pH value of the drilling fluid.

[0059] For example, the high-temperature resistant oil-in-water primary emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate. Specifically, the compound is prepared by mixing fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate at a ratio of 3:1 at 40°C, and then thoroughly mixing and dissolving them with low-speed stirring to obtain a primary emulsifier with a high HLB value. The compounded primary emulsifier exhibits a synergistic effect in enhancing emulsification and dispersion.

[0060] For example, the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate (SP80); since its molecular structure contains hydrophilic hydroxyl groups, lipophilic oleic acid long-chain hydrocarbon groups and multiple ether bonds, its structure itself gives it good amphiphilicity. As an auxiliary emulsifier, it can be combined with a main emulsifier with a high HLB value to form a tightly structured composite interface film, thereby enhancing the emulsification effect.

[0061] For example, the viscosity enhancer is high-temperature resistant monomer macromolecular xanthan gum (XC); a relatively low concentration thereof can provide a higher viscosity, which can effectively improve the viscosity and stability of the drilling fluid.

[0062] For example, the plugging agent is calcium carbonate particles with a particle size of 5 microns; it plays a role of plugging and bridging, and when used in conjunction with a polymer fluid loss reducer, it can effectively reduce the fluid loss of drilling fluid.

[0063] The high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid of the present invention has the following advantages:

[0064] (1) Environmental protection: The drilling fluid system uses a self-synthesized polymer fluid loss reducer to replace the traditional sulfonated material and part or all of the bentonite. The bentonite can be added in trace amounts or not at all, which greatly reduces the use of fluid loss reducer materials, reduces the adverse impact on the environment, and reduces the thickening phenomenon of bentonite under high temperature conditions. For the solution without bentonite, it truly achieves an environmentally friendly drilling fluid system without soil phase and sulfonation, which meets the current environmental protection requirements.

[0065] (2) High efficiency: The preparation process of the drilling fluid is simple, which greatly shortens the laboratory and on-site preparation time, improves production efficiency and facilitates maintenance.

[0066] (3) Economical: The preparation cost of this drilling fluid is low. The use of a water-in-oil system means that only a small amount of oil phase is used in the system, which not only achieves the lubricity of oil-based drilling fluid but also takes into account the low cost of water-based drilling fluid. Only a small amount of core treatment agent is needed to complete the preparation of a drilling fluid that is resistant to temperatures of 180°C, which greatly reduces the cost of use.

[0067] In a fourth aspect, the present invention further provides a method for preparing the above-mentioned high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, the method comprising the following steps:

[0068] S21, mixing bentonite and fresh water to obtain bentonite slurry, placing the bentonite slurry and alkalinity regulator on a high-speed stirrer, stirring at high speed for 5-10 minutes, and then adding a tackifier and stirring at high speed for 5-10 minutes;

[0069] S22, add filtrate reducer and stir at high speed for 5-10 minutes;

[0070] S23, add the primary emulsifier and the auxiliary emulsifier, and stir at high speed for 5-10 minutes; add the oil phase and stir at high speed for 10 minutes;

[0071] S24, add the plugging agent and stir at high speed for 5-10 minutes;

[0072] S25, adding barite and stirring at high speed for more than 30 minutes to obtain a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid.

[0073] The preparation method of the drilling fluid of the present invention is simple and efficient, and the oil-in-water system achieves the lubricity of the oil-based drilling fluid while taking into account the low cost of the water-based drilling fluid.

[0074] In a preferred embodiment, the method comprises the following steps:

[0075] S21, mixing bentonite and fresh water to obtain bentonite slurry, placing the bentonite slurry and alkalinity regulator on a high-speed stirrer, stirring at high speed for 5 minutes, and then adding a tackifier and stirring at high speed for 5 minutes;

[0076] S22, add filtrate reducer and stir at high speed for 5-10 minutes;

[0077] S23, add the primary emulsifier and the auxiliary emulsifier, and stir at high speed for 10 minutes; add the oil phase and stir at high speed for 10 minutes;

[0078] S24, add plugging agent and stir at high speed for 10 minutes;

[0079] S25, adding barite and stirring at high speed for 35 minutes to obtain a high temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid.

[0080] For example, in steps S21-S25, the high-speed stirring speed used is 11000±300 rpm. Only when the stirring speed is high enough can a sufficient reaction be ensured.

[0081] Hereinafter, the high temperature resistant fluid loss reducer and the drilling fluid of the present invention will be described in detail through specific examples.

[0082] The bentonite in the following examples comes from Shak (Tianjin) Petroleum Technology Service Co., Ltd., caustic soda comes from Shak (Tianjin) Petroleum Technology Service Co., Ltd., the thickener monomer macromolecular xanthan gum (XC) comes from Shak (Tianjin) Petroleum Technology Service Co., Ltd., and the calcium carbonate particles come from Shak (Tianjin) Petroleum Technology Service Co., Ltd.

[0083] Example 1

[0084] This embodiment provides a high temperature resistant fluid loss additive and a preparation method thereof, comprising:

[0085] S11: Place a three-necked flask in a constant temperature water bath, maintain the temperature at 75°C, install a stirrer in the middle, and install condensers and thermometers on both sides; add deionized water into the three-necked flask and stir, then add purified itaconic acid and allyl phenyl sulfone in sequence 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%), with a mass ratio of itaconic acid to allyl phenyl sulfone of 2:1; add analytical grade NaOH to the monomer solution to adjust the pH value of the solution to 6-7, so that the solution is neutral; add initiator ammonium persulfate under nitrogen protection and stir, and continue stirring the solution for 7 hours.

[0086] S12: After the free radical polymerization reaction is completed, the reaction product is quickly poured into anhydrous ethanol while hot, and filtered using a Buchner funnel to collect the precipitate. The precipitate is repeatedly washed several times to remove residues and impurities, and the precipitate is placed in a drying oven to dry to obtain a white solid, which is the alternating binary copolymer.

[0087] S13, mixing the alternating binary copolymer and the salt-resistant layered chain silicate clay mineral halloysite in a mass ratio of 9:1 to obtain a high-temperature resistant fluid loss reducer, such as Figure 1 shown.

[0088] Example 2

[0089] This embodiment provides a high-temperature resistant desulfonated environmentally friendly water-in-water drilling fluid and a preparation method thereof, comprising: weighing 196 ml of a bentonite slurry with a concentration of 0.5% using a high-stirring cup, adding 0.5 ppb of caustic soda, placing it on a high-speed stirrer, and stirring at a high speed of 12,000 rpm for 5 minutes; adding 4 ppb of the high-temperature resistant fluid loss reducer prepared in Example 1, and stirring at a high speed of 12,000 rpm for 5 minutes; adding 8 ppb of a primary emulsifier and 4 ppb of an auxiliary emulsifier, and stirring at a high speed of 12,000 rpm for 10 minutes; adding 84 ml of 3# white oil, and stirring at a high speed of 12,000 rpm for 10 minutes; adding 7 ppb of calcium carbonate particles with a particle size of 5 microns, and stirring at a high speed of 12,000 rpm for 10 minutes; adding barite of a designed density, and stirring at a high speed of 12,000 rpm for 35 minutes to obtain a water-in-water drilling fluid sample with an oil content of 30%.

[0090] Among them, the main emulsifier is a compound of fatty alcohol polyoxyethylene ether (AEO) and sodium dodecylbenzene sulfonate (LAS). The two emulsifiers are compounded in a ratio of 3:1 at 40°C, and are fully mixed and dissolved by low-speed stirring to obtain an emulsifier with a high HLB value; the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate (SP80).

[0091] Example 3

[0092] This embodiment provides a soil-free, high-temperature-resistant, desulfonated, environmentally friendly oil-in-water drilling fluid and a preparation method thereof.

[0093] 196 ml of fresh water was weighed using a high-speed stirring cup, 0.5 ppb of caustic soda was added, and the mixture was placed on a high-speed stirrer and stirred at 12,000 rpm for 5 minutes; 4 ppb of the thickener monomer macromolecular xanthan gum (XC) was added and stirred at 12,000 rpm for 5 minutes; 4 ppb of the high-temperature resistant fluid loss reducer prepared in Example 1 was added and stirred at 12,000 rpm for 5 minutes; 15 ppb of the primary emulsifier was added and stirred at 12,000 rpm for 10 minutes; 84 ml of 3# white oil was added and stirred at 12,000 rpm for 10 minutes; 10 ppb of calcium carbonate particles with a particle size of 5 microns was added and stirred at 12,000 rpm for 10 minutes; and barite of the designed density was added and stirred at 12,000 rpm for 35 minutes to obtain an oil-in-water drilling fluid sample with an oil content of 30%.

[0094] The product was tested using two indicators, using Test Examples 1 and 2 respectively.

[0095] Test Example 1

[0096] The rheological properties and thermal stability of the drilling fluids of Examples 2-3 above were tested. The specific testing methods are as follows:

[0097] Take the drilling fluid out of the aging kettle and put it into a high-speed stirring cup, stirring it at 12000rpm for 10min. Use Fann35 or its similar products to test its rheological properties. Transfer the tested drilling fluid to the specified scale line in the aging kettle; roll it at a constant temperature for 16h under the set bottom hole temperature; after the rolling time is over, take it out and cool it naturally to room temperature before opening it; put a glass rod with a diameter of 0.5cm and a length of 30cm from a position 2cm above the tank surface, respectively according to Figure 2 The test points shown are allowed to fall freely to determine the state of the drilling fluid.

[0098] The criteria for judging the drilling fluid status are as follows:

[0099] (1) When the glass rod contacts the bottom of the aging kettle, it can be heard to make a sound of impact, bounce quickly, and quickly lean against the wall. The sample in the kettle is poured out, and the flow pattern is a continuous and uninterrupted linear outflow. If there is no hard precipitation at the bottom of the kettle by naked eye, it indicates that the drilling fluid has not settled.

[0100] (2) No or only a faint sound can be heard when the glass rod contacts the bottom of the aging kettle. The sample is not leaning against the wall or leaning against the wall slowly. When pouring out the sample from the tank, the flow pattern is discontinuous and there are lumps. If there is hard sediment at the bottom of the kettle by naked eye, it indicates that the drilling fluid has settled. The degree of settlement is determined by the amount of hard sediment at the bottom. If the soft sediment at the bottom exceeds 1 cm or hard sediment, the drilling fluid has poor thermal stability and is not conducive to field operations.

[0101] Test Example 2

[0102] The drilling fluids of Examples 2-3 above were tested for filtration loss. The specific testing method is as follows:

[0103] The Fann HT 4700 filter loss meter was used to measure the drilling fluid loss and observe the filter cake condition. The criteria for judging the drilling fluid loss and mud cake are as follows:

[0104] (1) The filtration loss of drilling fluid in 30 minutes should be less than 10 ml;

[0105] (2) The filter cake thickness should be less than 3 mm and should be thin, smooth, dense and tough.

[0106] (3) If the filtration loss exceeds 10 ml and the mud cake is hollow, thick, rough, not dense, and not tough, the drilling fluid has poor thermal stability and is not conducive to field operations.

[0107] The test results of Example 2 are shown in Tables 1 and 2.

[0108] (1) The rheological properties of the drilling fluid after aging at 140°C for 16 hours are shown in Table 1 below:

[0109]

[0110] Note: 600, 300, 200, 100. 6. 3, all are the corresponding speeds of the six-speed viscometer, such as: The parameter corresponding to 600 is the reading at 600 revolutions; the gel strength at the initial shear force of 10 seconds is the minimum shear stress required to destroy the gel structure after the drilling fluid has been stationary for 10 seconds, which is also a reading value; the gel strength at the final shear force of 10 minutes is the minimum shear stress required to destroy the gel structure after being stationary for 10 minutes, which is also a reading value; PV is the plastic viscosity, which reflects the internal friction between the solid particles and between the solid and liquid phases in the drilling fluid under laminar flow conditions. 600- YP is the dynamic shear force (yield value), which is the minimum shear stress of the drilling fluid to form a dynamic grid structure under laminar flow state, representing the suspension capacity, which is 0.511× (2× 300- 600) value; FL HTHP is the high-temperature and high-pressure filtration loss, which represents the plugging ability of the drilling fluid; FC is the mud cake thickness after the high-temperature and high-pressure filtration loss test.

[0111] (2) The rheological properties of the drilling fluid after aging at 180°C for 16 hours are shown in Table 2 below:

[0112]

[0113] 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 , with a maximum temperature resistance of 180°C. When the drilling fluid was hot-rolled at 140°C for 16 hours, the system maintained excellent initial and final shear forces of 8 / 8 Pa and a dynamic shear force of 26 Pa, while also maintaining a low plastic viscosity of only 58 mPa.s. When the drilling fluid was hot-rolled at 180°C for 16 hours, the system still maintained excellent shear force and low plastic viscosity, with a 180°C HTHP fluid loss of only 10 ml.

[0114] It can be seen that this formula not only meets the requirements of on-site construction, but also further reduces the adverse impact on the environment.

[0115] The test results of Example 3 are shown in Tables 3 and 4.

[0116] (1) The rheological properties of the drilling fluid after aging at 140°C for 16 hours are shown in Table 3 below:

[0117]

[0118] (2) The rheological properties of the drilling fluid after aging at 180°C for 16 hours are shown in Table 4 below:

[0119]

[0120] It can be seen from Tables 3 and 4 that the density of the drilling fluid formula is 1.8 g / cm 3 , with a maximum temperature resistance of 180°C. After removing bentonite, the overall viscosity of the drilling fluid decreased. Whether hot-rolled for 16 hours at 140°C or 180°C, the drilling fluid system maintained excellent dynamic shear strength and low plastic viscosity, with a 180°C HTHP fluid loss of only 10.8ml.

[0121] It can be seen that the drilling fluid formula of the present invention not only meets the requirements of on-site construction, but also further reduces the adverse impact on the environment.

[0122] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A high temperature resistant fluid loss reducer, characterized in that: The high-temperature resistant fluid loss additive includes an alternating binary copolymer and a salt-resistant layered chain silicate clay mineral, wherein the alternating binary copolymer is obtained by free radical polymerization of itaconic acid and allyl phenyl sulfone; the mass ratio of itaconic acid to allyl phenyl sulfone is 1-3:1; and the alternating binary copolymer is a polymer with different segment structures and lengths.

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 method for preparing the high temperature resistant fluid loss reducer according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S11, dissolving itaconic acid and allylphenyl sulfone in deionized water, adjusting the pH to 6-7, and adding ammonium persulfate as an initiator under nitrogen protection to carry out a free radical polymerization reaction; S12, after the free radical polymerization reaction is completed, the reaction product is quickly poured into anhydrous ethanol, filtered to obtain a precipitate, and the precipitate is washed and dried to obtain a white solid, which is an alternating binary copolymer; S13, mixing the alternating binary copolymer with a salt-resistant layered chain silicate clay mineral to obtain a high-temperature resistant fluid loss reducer.

4. The preparation method according to claim 3, characterized in that The temperature of the free radical polymerization reaction is 60-80° C., and the time is 6-10 hours.

5. 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.

6. A high temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid, characterized in that: The high-temperature resistant fluid loss reducer according to claim 1 or 2 also includes fresh water, base oil, bentonite, alkalinity regulator, high-temperature resistant oil-in-water primary emulsifier, auxiliary emulsifier, viscosity enhancer, plugging agent and barite, wherein the bentonite and viscosity enhancer can be added separately or simultaneously.

7. The high temperature resistant desulfonated environment-friendly oil-in-water drilling fluid according to claim 6, characterized in that: Based on the total volume of fresh water and base oil, the fresh water content is 70-90%, and the base oil content 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: 0%-1% bentonite, 0.1%-0.3% alkalinity regulator, 2%-4% high-temperature resistant oil-in-water primary emulsifier, 0%-2% secondary emulsifier, 0%-1% viscosity enhancer, 0.5%-2% high-temperature resistant fluid loss reducer, 1%-2% plugging agent, and the barite content is determined according to the target density of the drilling fluid.

8. The high temperature resistant desulfonated environment-friendly oil-in-water drilling fluid according to claim 6, characterized in that: The alkalinity regulator is caustic soda; the high-temperature resistant oil-in-water main emulsifier is a compound of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate; the auxiliary emulsifier is a lipophilic nonionic surfactant sorbitan monooleate; the viscosity enhancer is a high-temperature resistant monomer macromolecular xanthan gum; and the plugging agent is calcium carbonate particles with a particle size of 5 microns.

9. A method for preparing the high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid according to any one of claims 6 to 8, characterized in that: The method comprises the following steps: S21, mixing bentonite and fresh water to obtain bentonite slurry, placing the bentonite slurry and alkalinity regulator on a high-speed stirrer, stirring at high speed for 5-10 minutes, and then adding a tackifier and stirring at high speed for 5-10 minutes; S22, add filtrate reducer and stir at high speed for 5-10 minutes; S23, add the primary emulsifier and the auxiliary emulsifier, and stir at high speed for 5-10 minutes; add the oil phase and stir at high speed for 10 minutes; S24, add the plugging agent and stir at high speed for 5-10 minutes; S25, adding barite and stirring at high speed for more than 30 minutes to obtain a high-temperature resistant desulfonated environmentally friendly oil-in-water drilling fluid.

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