Temperature-resistant and salt-resistant cross-linking tackifying filtrate reducer for soilless phase water-based drilling fluid as well as preparation method and application of temperature-resistant and salt-resistant cross-linking tackifying filtrate reducer

Abstract

The invention provides a temperature-resistant and salt-resistant cross-linking tackifying filtrate reducer for a soil-phase-free water-based drilling fluid as well as a preparation method and application of the temperature-resistant and salt-resistant cross-linking tackifying filtrate reducer, and belongs to the technical field of drilling. The temperature-resistant and salt-resistant cross-linking tackifying filtrate reducer for the soilless phase water-based drilling fluid comprises the following raw materials in parts by weight: N, N-dimethylformamide, a cross-linking agent and a cross-linking agent, the invention relates to a water-based adhesive which is prepared from the following components in parts by weight: 15 to 25 parts of N, N-dimethylacrylamide, 1 to 10 parts of 3-[(3-methacrylamidopropyl) dimethylammonium] propane-1-sulfonate, 1 to 10 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005 to 0.015 part of macromolecular cross-linking agent, 0.03 to 0.08 part of initiator A and 80 to 100 parts of deionized water. The tackifying filtrate reducer can resist the temperature of 180 DEG C, can resist NaCl to be saturated, has excellent tackifying, shear-improving and filtrate-reducing effects under high-temperature and high-salt conditions, improves the rheological property and the filtrate-reducing property of drilling fluid, and ensures safe and efficient drilling of a deep well.

Description

Technical Field

[0001] The invention relates to a temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid and a preparation method and application thereof, belonging to the technical field of drilling. Background Art

[0002] As the drilling depth increases, the risk and difficulty of drilling increase step by step. Especially under high temperature (180℃) and high salt (>15% NaCl) conditions, the dehydration of bentonite and the thermal degradation and desorption of fluid loss reducers will lead to the deterioration of the rheological and fluid loss properties of water-based drilling fluids, frequent downhole complex accidents such as wellbore collapse, stuck pipe, and overflow, and even cause the wellbore to be scrapped in severe cases. Soil-free water-based drilling fluid is a drilling fluid that does not contain clay materials such as bentonite. Compared with clay-containing water-based drilling fluids, it has the characteristics of high mechanical drilling speed, good lubricity, good rock carrying ability, good reservoir protection, and excellent salt resistance, and has broad application prospects. However, soil-free drilling fluid does not contain bentonite, and it is impossible to rely on the grid structure formed by bentonite and polymer to make the drilling fluid have the rheological properties required for drilling. Especially under the harsh conditions of high temperature, high salt, and high density, the treatment agent needs to have excellent temperature and salt resistance to play a good role in viscosity increase and shear enhancement.

[0003] At present, patent literature has reported more on two types of thickeners: natural modified polymers and artificial synthetic polymers. Chinese patent document CN109796946A provides a hydroxyethyl psyllium husk-nanosilica composite thickener. When the thickener is added at 0.5%, the apparent viscosity of the system is 22.0 mPa·s, which is higher than the 18.0 mPa·s of 5% bentonite-based slurry. When the thickener is added at 1%, the viscosity reduction rate of the system after aging at 150°C for 16 hours is less than 30%. Chinese patent document CN102127401A discloses a high temperature resistant thickener composed of starch, guar gum, alkaline hydroxide, epoxide and alcohol solvent. The thickener is resistant to temperatures of up to 150°C in fresh water, 130°C in seawater, and 120°C in brine. Chinese patent document CN106608945A discloses a copolymer thickener, which is mainly composed of N,N-dimethylacrylamide, N-methyldiallyl propane sulfonate, and cationic polyamine association body. The thickener can withstand temperatures up to 180°C, resists NaCl concentration to saturation, resists CaCl2 concentration to 20%, and has good thickening, inhibition and filtration loss reduction performance in 4% calcium bentonite-based slurry. Chinese patent document CN104140790A discloses a polymer thickener and its preparation method. The polymer thickener is prepared from polyvinyl alcohol and xanthan gum. After adding 2% of the thickener to a 15% calcium chloride aqueous solution, the apparent viscosity of the drilling fluid after aging at 120°C for 16 hours is 22mPa·s. Chinese patent document CN101845295A discloses a drilling fluid thickener, which is compounded by a tetrapolymer and a diquaternary ammonium salt. The thickener forms earthworm-shaped or long rod-shaped micelles in water through molecular association, thereby effectively increasing the viscosity of the drilling fluid. When the thickener is added at 1.5%, the apparent viscosity of the solid-free drilling fluid after aging at 100°C for 16 hours is 36 mPa·s, the plastic viscosity is 17 mPa·s, and the shear force is 19 Pa. Chinese patent document CN100549123C discloses a thickener, which is compounded by sulfonate anionic active agent, quaternary ammonium salt or pyridinium salt cationic active agent, industrial formaldehyde and industrial alcohol. When 3% thickener is added to 1% hydroxyethyl cellulose saturated salt solution, the viscosity of the solution after aging at 150°C increases from 3mPa·s to 26mPa·s. When 3% thickener is added to 0.5% HPAM aqueous solution, the viscosity of the solution after aging at 150°C increases from 3mPa·s to 20mPa·s. Chinese patent document CN104650827A discloses a non-solid phase drilling fluid thickener polymerized by N,N-dimethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-vinyl caprolactam and divinylbenzene as monomers, with a temperature resistance of 165°C. CN107235863A discloses a hydrophobic associating polymer prepared by polymerization of a hydrophobic monomer containing a benzene ring and N-vinyl pyrrolidone, which has a temperature resistance of up to 150°C.CN107235862A discloses a non-solid phase drilling fluid polymer thickener with a temperature resistance of up to 150° C. Hydrophobic groups of benzene rings and long fluorocarbon chains are introduced into the thickener molecules, which can form a three-dimensional network structure through hydrophobic association, thereby effectively increasing the viscosity of the solution.

[0004] Although there are many types of existing viscosifiers, their temperature and salt resistance are insufficient and cannot meet the performance requirements of high temperature (180°C) and high salt (>15% NaCl). Therefore, it is urgent to develop a high-efficiency viscosifier and filtrate reducer to effectively maintain the rheological properties of soil-free drilling fluid under high temperature and high salt conditions. Summary of the invention

[0005] In view of the shortcomings of the prior art, especially the poor temperature and salt resistance of the existing thickeners for soilless water-based drilling fluids, which cannot maintain the rheological properties of the soilless water-based drilling fluids under high temperature and high salt conditions, the present invention provides a temperature-resistant and salt-resistant cross-linked thickening and filtration-reducing agent for soilless water-based drilling fluids and a preparation method and application thereof. The thickening and filtration-reducing agent of the present invention has the effects of increasing viscosity, improving shear and reducing filtration under high temperature and high salt conditions, and can improve the rheological and filtration-loss properties of the soilless water-based drilling fluids under high temperature and high salt conditions.

[0006] The present invention is achieved through the following technical solutions: A temperature-resistant and salt-resistant cross-linked viscosity-enhancing and fluid loss reducer for soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 15-25 parts of N,N-dimethylacrylamide, 1-10 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 1-10 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005-0.015 parts of a macromolecular cross-linking agent, 0.03-0.08 parts of an initiator A, and 80-100 parts of deionized water.

[0007] According to the present invention, the 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate can be commercially available or prepared according to the following method: Dissolving N-[3-(dimethylamino)propyl]methacrylamide in acetonitrile to obtain solution 1, dissolving 1,3-propane sultone in acetonitrile to obtain solution 2, adding solution 1 dropwise into solution 2, and reacting after the addition is complete; after the reaction is complete, cooling, removing the solvent, and drying to obtain 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate; Further preferably, the mass ratio of N-[3-(dimethylamino)propyl]methacrylamide to acetonitrile in the solution 1 is 1:3-15, the mass ratio of 1,3-propane sultone to acetonitrile in the solution 2 is 1:2.5-12; the molar ratio of N-[3-(dimethylamino)propyl]methacrylamide to 1,3-propane sultone is 1:1.2-3; and the dripping rate of the solution 1 is 3-8 mL / min.

[0008] Further preferably, in the preparation of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, the reaction temperature is 70-90°C, the reaction time is 20-30h; and the drying is vacuum drying at 80-100°C for 20-30h.

[0009] According to the present invention, the reaction route for synthesizing 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate is as follows:

[0010] Preferably, according to the present invention, the structural formula of the long-chain alkyl polyoxyethylene ether methacrylate is shown in Formula I below: Formula I; In formula I, n is an integer between 20 and 30, and R is a straight chain hydrocarbon group having 16 to 25 carbon atoms.

[0011] Preferably, according to the present invention, the macromolecular cross-linking agent is prepared according to the following method: (1) Add 2-acrylamido-2-methylpropanesulfonic acid and initiator B into deionized water and stir evenly to obtain an aqueous phase; (2) pentaerythritol triallyl ether, triallyl isocyanurate and cyclohexane are mixed, and then an emulsifier is added and stirred to obtain an oil phase; (3) Under stirring conditions, the water phase is added to the oil phase, and the resulting mixed system is then sheared and emulsified to obtain an oil-in-water emulsion; the emulsion is transferred to a three-necked flask for reaction; after the reaction is completed, the emulsion is washed and dried to obtain a macromolecular cross-linking agent.

[0012] Preferably, according to the present invention, the initiator B in step (1) is azobisisobutylamidine dihydrochloride, azobisisobutyronitrile, ammonium persulfate or potassium persulfate, and the mass ratio of the initiator B to 2-acrylamido-2-methylpropanesulfonic acid is 0.01-0.1:10.

[0013] Preferably, according to the present invention, the mass ratio of 2-acrylamido-2-methylpropanesulfonic acid to deionized water in step (1) is 1:2.5-7.

[0014] Preferably, according to the present invention, the mass ratio of pentaerythritol triallyl ether, triallyl isocyanurate and 2-acrylamido-2-methylpropane sulfonic acid in step (2) is 0.05-0.10:0.05-0.10:5-10.

[0015] Preferably, according to the present invention, the emulsifier in step (2) is a composition of Span 80 and Tween 80, the mass ratio of Tween 80 to Span 80 in the composition is 1-3:2-6, and the mass ratio of the emulsifier to cyclohexane is 1:7-15.

[0016] Preferably, according to the present invention, the stirring speed in step (3) is 500-1500 rpm, and the mass ratio of deionized water in the aqueous phase to cyclohexane in the oil phase is 20-50:60-80.

[0017] Preferably, according to the present invention, the rotation speed of the shear emulsification in step (3) is 5000-10000 rpm, and the time of the shear emulsification is 10-30 min.

[0018] Preferably, according to the present invention, the reaction temperature in step (3) is 50-70° C., and the reaction time is 3-5 h.

[0019] Preferably, in step (3), the washing is performed by immersing in ethanol for 3-5 times, and the drying is performed by vacuum drying at 80-100° C. for 20-30 hours.

[0020] Preferably according to the present invention, the initiator A is azobisisobutylamidine dihydrochloride, azobisisobutyronitrile, ammonium persulfate or potassium persulfate.

[0021] According to the present invention, the preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid comprises the following steps: N,N-dimethylacrylamide, 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, long-chain alkyl polyoxyethylene ether methacrylate and macromolecular crosslinking agent are added into deionized water and stirred evenly to obtain a mixed solution; the mixed solution is heated to a reaction temperature, and an initiator A is added to react; after the reaction is completed, the mixture is washed, dried and crushed to obtain a temperature-resistant and salt-resistant crosslinked viscosity-enhancing fluid loss reducer for a soil-free water-based drilling fluid.

[0022] Preferably according to the present invention, the reaction temperature is 60-80°C, the reaction time is 3-5h; the washing is 2-3 times with acetone and 1-2 times with anhydrous ethanol; the drying is vacuum drying at 80-100°C to constant weight.

[0023] According to the present invention, the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing filtrate reducer for soil-free water-based drilling fluid is used in soil-free water-based drilling fluid, and the concentration of the temperature-resistant and salt-resistant cross-linked viscosity-increasing filtrate reducer for soil-free water-based drilling fluid in the soil-free water-based drilling fluid is 1-2wt%.

[0024] The technical features and beneficial effects of the present invention are as follows: 1. The macromolecular crosslinking agent of the present invention is prepared by free radical polymerization of 2-acrylamido-2-methylpropanesulfonic acid, pentaerythritol triallyl ether and triallyl isocyanurate. The macromolecular crosslinking agent has a three-dimensional crosslinked network structure and has stronger temperature resistance than conventional olefin crosslinking agents. The heat-resistant and heat-resistant macromolecular crosslinking agent crosslinks linear polymers to form a two-dimensional network structure, so that the viscosity-increasing fluid loss reducer has excellent high-temperature hydrolysis stability, thereby exerting excellent viscosity-increasing, shear-enhancing and fluid loss reduction effects under high temperature and high salt conditions.

[0025] 2. The viscosity-enhancing and fluid loss-reducing agent copolymer of the present invention contains zwitterionic side chains, thus having an anti-polyelectrolyte effect. As the salt concentration increases, the copolymer molecular chain gradually stretches, and the fluid mechanics radius increases, so that the copolymers can form a spatial network structure through intermolecular forces such as hydrogen bonds and electrostatic forces. The long-chain alkyl groups give the copolymers hydrophobic association properties. Under high-salt conditions, the copolymers can form an association network through hydrophobic interactions, further strengthening the internal spatial network structure of the drilling fluid and enhancing the viscosity-enhancing, shear-enhancing and fluid loss-reducing properties of the copolymers. The synergistic effects of the micro-crosslinked structure, anti-polyelectrolyte and hydrophobic association make the viscosity-enhancing and fluid loss-reducing agent of the present invention have excellent temperature and salt resistance.

[0026] 3. The viscosity increasing and filtration reducing agent for soil-free water-based drilling fluid of the present invention can resist temperatures up to 180°C and salt to saturation. It can effectively maintain the viscosity and shear force of soil-free water-based drilling fluid under high temperature and high salt conditions, reduce the filtration loss, and improve the rheology and filtration loss of the drilling fluid. It is suitable for soil-free drilling fluids of fresh water, sea water, salt water and saturated salt water, and the recommended addition amount is 1-2%. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific examples so that those skilled in the art can better understand the present invention and implement it, but the examples are not intended to limit the present invention. The materials used in the examples can be obtained from commercial sources unless otherwise specified.

[0028] The "parts" described in the present invention are all parts by weight.

[0029] Preparation Example 1 Preparation of 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate 9.38 g of N-[3-(dimethylamino)propyl]methacrylamide was dissolved in 50 g of acetonitrile to obtain solution 1; 10.99 g of 1,3-propane sultone was dissolved in 50 g of acetonitrile to obtain solution 2, and solution 1 was slowly added dropwise into solution 2 at a rate of 5 mL / min using a constant pressure funnel. After the addition was completed, the obtained mixed solution was heated to 80° C. and reacted for 24 h at a stirring rate of 300 rpm. After the reaction was completed, it was naturally cooled to room temperature, and the acetonitrile was removed by rotary evaporation at 90° C., and finally vacuum dried at 90° C. for 24 h. The obtained white powder was 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate.

[0030] Preparation Example 2 Preparation of macromolecular cross-linking agents Weigh 33g of deionized water in a beaker, add 10g of 2-acrylamido-2-methylpropanesulfonic acid and 0.08g of azobisisobutylamidine dihydrochloride (V50) into the deionized water, stir thoroughly for 20 minutes to obtain an aqueous phase; then add 0.05g of pentaerythritol triallyl ether, 0.05g of triallyl isocyanurate and 66g of cyclohexane into the beaker, then add 3.5g of Span 80 and 3.5g of Tween 80, stir thoroughly for 20 minutes to obtain an oil phase; add the aqueous phase into the oil phase at a stirring rate of 1000rpm, and when the aqueous phase is completely added to the oil phase, shear emulsify the resulting mixed system at a rate of 8000rpm for 20 minutes on an emulsifier to obtain an oil-in-water emulsion; transfer it to a three-necked flask, heat it to 60°C, and continue the reaction for 4h at a stirring rate of 350 rpm in a nitrogen atmosphere. The reaction product was washed in anhydrous ethanol for three times, and the precipitate was vacuum dried at 90° C. for 24 h to obtain a macromolecular cross-linking agent.

[0031] The 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate and the macromolecular cross-linking agent used in the examples and comparative examples were prepared from comparative examples 1 and 2, respectively.

[0032] Example 1 A temperature-resistant and salt-resistant cross-linked viscosity-enhancing fluid loss reducer for a soil-free water-based drilling fluid, comprising the following raw materials in parts by weight: 20 parts of N,N-dimethylacrylamide, 5 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 5 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; Wherein, the structural formula of long-chain alkyl polyoxyethylene ether methacrylate is shown in the following formula I: Formula I; In formula I, n is 20, and R is a straight-chain hydrocarbon group having 22 carbon atoms; The initiator A is azobisisobutylamidine dihydrochloride.

[0033] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid comprises the following steps: Deionized water was added to a three-necked flask, and N,N-dimethylacrylamide, 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, long-chain alkyl polyoxyethylene ether methacrylate and a macromolecular crosslinking agent were added to the deionized water, and the mixture was stirred for 20 minutes to disperse the monomers evenly to obtain a mixed solution; the mixed solution was heated to 70°C, and initiator A was added to initiate free radical polymerization, and the reaction was continued for 4 hours to obtain a transparent gel; the gel was washed with acetone twice, and then washed with anhydrous ethanol once, and then the gel was placed at 90°C and vacuum dried to constant weight, and crushed to obtain a temperature-resistant and salt-resistant cross-linked viscosity-enhancing and filtration-reducing agent A1 for soil-free water-based drilling fluid.

[0034] Example 2 A temperature-resistant and salt-resistant cross-linked viscosity-increasing and fluid loss reducer for a soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 20 parts of N,N-dimethylacrylamide, 5 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 5 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.01 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; other raw materials are selected as described in Example 1.

[0035] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid is as described in Example 1, and the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer A2 for soil-free water-based drilling fluid is obtained.

[0036] Example 3 A temperature-resistant and salt-resistant cross-linked viscosity-increasing and fluid loss reducer for a soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 20 parts of N,N-dimethylacrylamide, 5 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 5 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.015 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; other raw materials are selected as described in Example 1.

[0037] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid is as described in Example 1, and the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer A3 for soil-free water-based drilling fluid is obtained.

[0038] Example 4 A temperature-resistant and salt-resistant cross-linked viscosity-increasing and fluid loss reducer for a soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 25 parts of N,N-dimethylacrylamide, 5 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 5 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; other raw materials are selected as described in Example 1.

[0039] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid is as described in Example 1, and the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer A4 for soil-free water-based drilling fluid is obtained.

[0040] Example 5 A temperature-resistant and salt-resistant cross-linked viscosity-increasing and fluid loss reducer for a soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 20 parts of N,N-dimethylacrylamide, 10 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 5 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; other raw materials are selected as described in Example 1.

[0041] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid is as described in Example 1, and the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer A5 for soil-free water-based drilling fluid is obtained.

[0042] Example 6 A temperature-resistant and salt-resistant cross-linked viscosity-increasing and fluid loss reducer for a soil-free water-based drilling fluid comprises the following raw materials in parts by weight: 20 parts of N,N-dimethylacrylamide, 5 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 10 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005 parts of a macromolecular cross-linking agent, 0.03 parts of an initiator A, and 80 parts of deionized water; other raw materials are selected as described in Example 1.

[0043] The preparation method of the above-mentioned temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid is as described in Example 1, and the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer A6 for soil-free water-based drilling fluid is obtained.

[0044] Comparative Example 1 A viscosity increasing and fluid loss reducing agent for soil-free water-based drilling fluid is as described in Example 1, except that the macromolecular cross-linking agent is 0.02 parts.

[0045] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer is as described in Example 1, and the soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer D1 is obtained.

[0046] Comparative Example 2 A viscosity increasing and fluid loss reducing agent for soil-free water-based drilling fluid is as described in Example 1, except that no macromolecular cross-linking agent is added.

[0047] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity increasing and fluid loss reducer is as described in Example 1, except that the step of adding a macromolecular cross-linking agent is omitted to obtain the soil-free water-based drilling fluid viscosity increasing and fluid loss reducer D2.

[0048] Comparative Example 3 A viscosity increasing and fluid loss reducing agent for a soil-free water-based drilling fluid is as described in Example 1, except that 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate is not added.

[0049] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity increasing and fluid loss reducer is as described in Example 1, except that the step of adding 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate is omitted to obtain the soil-free water-based drilling fluid viscosity increasing and fluid loss reducer D3.

[0050] Comparative Example 4 A viscosity increasing and fluid loss reducing agent for soil-free water-based drilling fluid is as described in Example 1, except that no long-chain alkyl polyoxyethylene ether methacrylate is added.

[0051] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity increasing and fluid loss reducer is as described in Example 1, except that the step of adding long-chain alkyl polyoxyethylene ether methacrylate is omitted to obtain the soil-free water-based drilling fluid viscosity increasing and fluid loss reducer D4.

[0052] Comparative Example 5 A viscosity increasing and fluid loss reducing agent for soil-free water-based drilling fluid is as described in Example 1, except that the macromolecular cross-linking agent is replaced by an equal mass of N,N-dimethylenebisacrylamide.

[0053] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer is as described in Example 1, and the soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer D5 is obtained.

[0054] Comparative Example 6 A viscosity increasing and fluid loss reducing agent for soil-free water-based drilling fluid is as described in Example 1, except that the long-chain alkyl polyoxyethylene ether methacrylate is replaced by methyl methacrylate of equal mass.

[0055] The preparation method of the above-mentioned soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer is as described in Example 1, and the soil-free water-based drilling fluid viscosity-increasing and fluid loss reducer D6 is obtained.

[0056] Application Experiment Example 1 8 parts by weight of the viscosity increasing and filtration reducing agent A1-A6 in the embodiment are added to 400 parts by weight of deionized water, and after high-speed stirring at 6000 rpm for 20 minutes, 144 parts by weight of NaCl are added, and stirring is continued for 20 minutes to obtain drilling fluid F1-F6. In the same way, the viscosity increasing and filtration reducing agent D1-D6 in the comparative example are configured into drilling fluid DF1-DF6. The drilling fluid is placed in a stainless steel aging tank and rolled at a constant temperature of 180°C for 16 hours. After the aging is completed, it is cooled to room temperature and taken out, and stirred at 6000 rpm for 20 minutes. According to the petroleum and natural gas industry standard GB / T 29170-2012 "Petroleum and Natural Gas Industry-Drilling Fluid Laboratory Test", the apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API filtration loss FL of the drilling fluid before and after high-temperature aging are measured. API , the results are shown in Table 1.

[0057] Table 1 Drilling fluid performance test

[0058] The experimental results are shown in Table 1. When the viscosity increasing and fluid loss reducing agent is added to the saturated brine drilling fluid at a dosage of 2%, the AV of drilling fluids F1-F6 are all maintained in the range of 46.5mPa·s to 57.0mPa·s, and the AV after aging at 180℃ are all maintained in the range of 25.0mPa·s to 38.5mPa·s. The AV retention rates before and after aging are 53.76%, 62.37%, 67.54%, 56.25%, 59.18%, and 58.76%, respectively. The PV of drilling fluids F1-F6 before aging are all maintained in the range of 39.5mPa·s to 45.0mPa·s, and the PV after aging at 180℃ are all maintained in the range of 21.0mPa·s to 29.0mPa·s. The PV retention rates before and after aging are 53.16%, 61.73%, 64.44%, 53.75%, 56.79%, and 55.56%, respectively. The YP of drilling fluids F1-F6 before aging was maintained in the range of 7.0mPa·s to 12.0mPa·s, and the YP after aging at 180°C was maintained in the range of 4.0Pa to 9.5Pa. The YP retention rates before and after aging were 57.14%, 65%, 79.17%, 68.75%, 70.59%, and 75.0%. The retention rates of AV, PV, and YP of drilling fluids F1-F6 before and after aging were all greater than 50%, indicating that the viscosity-enhancing and fluid-loss reducer of the present invention has good temperature resistance, salt resistance, viscosity-enhancing, and shear-enhancing properties. With the increase in the amount of cross-linking agent, the AV, PV, and YP of the drilling fluid before and after aging at 180°C all showed an upward trend, indicating that the macromolecular cross-linking agent effectively enhanced the temperature resistance of the viscosity-enhancing and fluid-loss reducer. When the dosage of N,N-dimethylacrylamide, 3-[(3-methacrylamidepropyl)dimethylammonium]propane-1-sulfonate, and long-chain alkyl polyoxyethylene ether methacrylate is increased, the viscosity-increasing, shear-increasing, and fluid loss-reducing properties of the copolymer are improved. This is because the dimethyl, sulfonic acid, and long alkyl chains have rigidity and high-temperature hydrolysis resistance, which effectively improves the heat resistance of the polymer. The FL of drilling fluid F1-F6 after aging at 180°C API They are 16.0, 14.8, 12.6, 15.8, 15.0 and 15.4 mL respectively, indicating that the viscosity increasing filtrate reducer of the present invention also has good filtrate reducing performance.

[0059] As can be seen from Comparative Example 1, when the amount of cross-linking agent is further increased, the viscosity and shearing effects of the viscosity-increasing and fluid loss reducer before aging are poor, because excessive cross-linking agent will cause the polymer to form a three-dimensional structure, that is, a water-insoluble microgel. The three-dimensional cross-linked structure of the microgel degrades under high temperature conditions, prompting the polymer to dissolve, so the drilling fluid after aging can still maintain a certain viscosity, shear force and low fluid loss. From Comparative Examples 2 and 5, it can be seen that when the anti-macromolecule cross-linking agent is removed, or the macromolecule cross-linking agent is replaced by the conventional olefin cross-linking agent N, N-dimethylenebisacrylamide, the temperature resistance of the viscosity-increasing and fluid loss reducer is greatly reduced, and the viscosity and shear force of the drilling fluid after aging at 180°C are low, and the fluid loss is large. From Comparative Example 3, it is known that when 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate is removed, the viscosity-increasing and fluid loss reducer does not have an anti-polyelectrolyte effect, has poor salt resistance, and has a low viscosity and shear force of the drilling fluid after aging at 180°C, and a large fluid loss. From Comparative Examples 4 and 6, it can be seen that when the hydrophobic monomer long-chain alkyl polyoxyethylene ether methacrylate is removed or replaced with methyl methacrylate without a long-chain alkyl group, the hydrophobic association of the viscosity-increasing fluid loss agent is weak, so the performance of the treatment agent decreases. The synergistic effect of the micro-crosslinked structure, the reverse polyelectrolyte effect and the hydrophobic association enables the viscosity-increasing fluid loss agent of the present invention to have excellent viscosity-increasing, shear-enhancing and fluid loss reduction effects under high temperature and high salt conditions.

[0060] Application Experiment Example 2 At a stirring rate of 6000 rpm, 400 parts by weight of deionized water were taken, 4 parts by weight of the viscosity increasing and fluid loss reducing agent A3 in Example 3, 20 parts by weight of ultrafine calcium carbonate (200 μm), and 144 parts by weight of sodium chloride were added to the deionized water in sequence, and then barite was added to prepare the density of 1.2, 1.4, 1.6, 1.8, and 2.0 g / cm 3 The soil-free water-based drilling fluids were recorded as F7, F8, F9, F10, and F11, and the drilling fluids without viscosity-enhancing and fluid loss reducer A3 were recorded as DF7, DF8, DF9, DF10, and DF11. The above drilling fluids were placed in a stainless steel aging tank and rolled at a constant temperature of 180°C for 16 hours. The apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), and API fluid loss FL before and after aging of the drilling fluids were tested. API and high temperature and high pressure filtration loss FL HTHP (180℃, 3.5MPa), the results are shown in Tables 2 and 3.

[0061] Table 2 Performance test of drilling fluid containing viscosity increasing and fluid loss reducing agent of the present invention

[0062] Table 3 Performance test of drilling fluid without viscosity increasing and fluid loss reducing agent of the present invention

[0063] From Table 2 and Table 3, we can see that the drilling fluid density is 1.2-2.0g / cm 3 The rheological parameters before and after aging at 180℃ are within a reasonable range. The drilling fluid can maintain a certain viscosity and shear force at low density, and its viscosity and shear force are not too high at high density. From the perspective of the filtration performance of the drilling fluid, when no viscosity increasing and filtration reducing agent is added, the FL API Total filtration, after adding 1% viscosity increasing and filtration reducing agent, the FL of drilling fluid before and after aging at 180℃ API All less than 10mL, FL HTHP There is also a certain degree of reduction. The viscosity-increasing fluid loss reducer has a soft polymer long chain and a cross-linked network structure, which can block the water loss pores inside the mud cake and effectively reduce the fluid loss. The experimental results show that the viscosity-increasing fluid loss reducer of the present invention has good viscosity-increasing, shear-enhancing and fluid loss-reducing effects in the soil-free saturated salt drilling fluid. During the drilling process, the viscosity-increasing fluid loss reducer can effectively improve and maintain the rheological and fluid loss properties of the soil-free drilling fluid, and improve the safety of drilling.

[0064] Application Experiment Example 3 8 parts by weight of viscosity increasing and fluid loss reducing agents A3, HE300, 80A51, Driscal D and Dristemp in Example 3 were added to 400 parts by weight of deionized water, and 144 parts by weight of NaCl were added after high-speed stirring at 6000 rpm for 20 minutes. The stirring was continued for 20 minutes to obtain drilling fluids F3 and DF12-DF15. The above drilling fluids were placed in a stainless steel aging tank and rolled at a constant temperature of 180°C for 16 hours. The apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API fluid loss FL before and after aging of the drilling fluid were tested. API , the results are shown in Table 4.

[0065] Table 4 Performance comparison of different types of tackifiers

[0066] As can be seen from Table 4, at 180°C and saturated NaCl conditions, after adding 2% of the viscosity increasing and fluid loss reducing agent A3 of Example 3, the AV of the drilling fluid is 38.5 mPa·s, PV is 29.0 mPa·s, YP is 9.5 Pa, and FL is 1.37 mPa·s. API The viscosity increasing and fluid loss reducing agent of the present invention is 12.6mL, which is higher than the AV, PV and YP of the drilling fluid added with HE300, 80A51, Driscal D and Dristemp, and the fluid loss is lower. This shows that the temperature resistance and salt resistance of the viscosity increasing and fluid loss reducing agent of the present invention are better than those of domestic and foreign viscosity increasing agents such as HE300, 80A51, Driscal D and Dristemp, and the viscosity increasing, shearing improving and fluid loss reducing effects are better under high temperature and high salt conditions.

[0067] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0069] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid, characterized in that: The invention comprises the following raw materials in parts by weight: 15-25 parts of N,N-dimethylacrylamide, 1-10 parts of 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, 1-10 parts of long-chain alkyl polyoxyethylene ether methacrylate, 0.005-0.015 parts of macromolecular crosslinking agent, 0.03-0.08 parts of initiator A, and 80-100 parts of deionized water; The 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate was prepared according to the following method: N-[3-(dimethylamino)propyl]methacrylamide is dissolved in acetonitrile to obtain solution 1, 1,3-propane sultone is dissolved in acetonitrile to obtain solution 2, solution 1 is added dropwise to solution 2, and after the addition is completed, a reaction is carried out; after the reaction is completed, the reaction is cooled, the solvent is removed, and the reaction is dried to obtain 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate; the molar ratio of N-[3-(dimethylamino)propyl]methacrylamide to 1,3-propane sultone is 1:1.2-3; The structural formula of the long-chain alkyl polyoxyethylene ether methacrylate is shown in Formula I below: Formula I; In Formula I, n is an integer between 20 and 30, and R is a straight chain hydrocarbon group having 16 to 25 carbon atoms; The macromolecular cross-linking agent is prepared according to the following method: (1) adding 2-acrylamide-2-methylpropanesulfonic acid and initiator B into deionized water, stirring evenly, to obtain an aqueous phase; the initiator B is azobisisobutylamidine dihydrochloride, azobisisobutyronitrile, ammonium persulfate or potassium persulfate, and the mass ratio of the initiator B to 2-acrylamide-2-methylpropanesulfonic acid is 0.01-0.1:10; (2) pentaerythritol triallyl ether, triallyl isocyanurate and cyclohexane are mixed, and then an emulsifier is added and stirred to obtain an oil phase; the mass ratio of pentaerythritol triallyl ether, triallyl isocyanurate and 2-acrylamido-2-methylpropane sulfonic acid is 0.05-0.10:0.05-0.10:5-10; and the emulsifier is a combination of Span 80 and Tween 80; (3) adding the water phase to the oil phase under stirring conditions, and then subjecting the resulting mixed system to shear emulsification to obtain a water-in-oil emulsion; Transfer it to a three-necked flask and react; after the reaction is completed, wash and dry to obtain a macromolecular crosslinking agent; the mass ratio of deionized water in the water phase to cyclohexane in the oil phase is 20-50:60-80; the reaction temperature is 50-70°C, and the reaction time is 3-5h; The initiator A is azobisisobutylamidine dihydrochloride, azobisisobutyronitrile, ammonium persulfate or potassium persulfate.

2. The temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 1, characterized in that: The mass ratio of N-[3-(dimethylamino)propyl]methacrylamide to acetonitrile in the solution 1 is 1:3-15, and the mass ratio of 1,3-propane sultone to acetonitrile in the solution 2 is 1:2.5-12; the dripping rate of the solution 1 is 3-8 mL / min.

3. The temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 1, characterized in that: In the preparation of 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate, the reaction temperature is 70-90° C., the reaction time is 20-30 h; and the drying is vacuum drying at 80-100° C. for 20-30 h.

4. The temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 1, characterized in that: The mass ratio of 2-acrylamido-2-methylpropanesulfonic acid to deionized water in step (1) is 1:2.5-7.

5. The temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 1, characterized in that: In the composition of step (2), the mass ratio of Tween 80 to Span 80 is 1-3:2-6, and the mass ratio of the emulsifier to cyclohexane is 1:7-15.

6. The temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 1, characterized in that: The stirring speed in step (3) is 500-1500 rpm; the shear emulsification speed is 5000-10000 rpm, and the shear emulsification time is 10-30 min; the washing is performed by immersion in ethanol for 3-5 times, and the drying is performed by vacuum drying at 80-100° C. for 20-30 h.

7. The method for preparing the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to any one of claims 1 to 6, characterized in that: The steps include: N,N-dimethylacrylamide, 3-[(3-methacrylamidopropyl)dimethylammonium]propane-1-sulfonate, long-chain alkyl polyoxyethylene ether methacrylate and macromolecular crosslinking agent are added into deionized water and stirred evenly to obtain a mixed solution; the mixed solution is heated to a reaction temperature, and an initiator A is added to react; after the reaction is completed, the mixture is washed, dried and crushed to obtain a temperature-resistant and salt-resistant crosslinked viscosity-enhancing fluid loss reducer for a soil-free water-based drilling fluid.

8. The method for preparing the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to claim 7, characterized in that: The reaction temperature is 60-80° C., and the reaction time is 3-5 hours. The washing is performed by washing with acetone for 2-3 times and then washing with anhydrous ethanol for 1-2 times. The drying is performed by vacuum drying at 80-100° C. to constant weight.

9. Use of the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for soil-free water-based drilling fluid according to any one of claims 1 to 6 in soil-free water-based drilling fluid, characterized in that: The concentration of the temperature-resistant and salt-resistant cross-linked viscosity-increasing fluid loss reducer for the soil-free water-based drilling fluid in the soil-free water-based drilling fluid is 1-2wt%.

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