Anti-180 ℃ saturated salt soil-free phase water-based drilling fluid and preparation method and application thereof

Abstract

The application provides an anti-180 DEG C saturated salt soil-free water-based drilling fluid and a preparation method and application thereof, and belongs to the technical field of drilling fluids. The anti-180 DEG C saturated salt soil-free water-based drilling fluid comprises the following raw materials in parts by mass: water 100 parts, a pH regulator 0.2-0.4 parts, a viscosity-increasing and filtration-reducing agent 2-3 parts, a high-temperature protective agent 1-5 parts, clinoptilolite 3-6 parts, fly ash 10-20 parts, modified polyurethane fiber 1-3 parts, emulsified asphalt 3-6 parts, and lubricant RH-3 1-2 parts. The soil-free water-based drilling fluid provided by the application has a temperature resistance of 180 DEG C, a salt resistance of saturation, good rheological and filtration-reducing properties under high-temperature and high-salt conditions, is suitable for deep salt-gypsum stratum drilling, guarantees deep drilling safety, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to an anti-180 DEG saturated salt soil-free phase water-based drilling fluid and a preparation method and application thereof, and belongs to the technical field of drilling fluids. BACKGROUND

[0002] Deep and ultra-deep oil and gas resources are rich in reserves, and it is of great significance to safely and efficiently develop deep oil and gas resources. The complex and harsh geological conditions of deep formations bring great challenges to drilling engineering. As the 'blood' of drilling engineering, the performance of drilling fluid will greatly affect the quality of drilling engineering, and the efficient development of deep oil and gas resources needs the support of high-performance drilling fluid. Soil-free phase water-based drilling fluid is a kind of water-based drilling fluid without clay-based viscosity increasing and shear raising agents, which can avoid the negative influence of unstable coagulation or dispersion of clay under high temperature and high salt conditions on the performance of drilling fluid, and is beneficial to the improvement of mechanical drilling speed and reservoir protection, and has a wide research and application prospect.

[0003] However, under high temperature and high salt conditions, the viscosity increasing and shear raising agents and the filtration reducing agents of the existing soil-free phase water-based drilling fluid are prone to failure, leading to the deterioration of the performance of the soil-free phase water-based drilling fluid, and causing complex accidents such as sticking and well collapse, prolonging the drilling cycle and increasing the drilling cost. A variety of soil-free phase water-based drilling fluids have been disclosed in existing patent documents, for example: Chinese patent document CN109266318A discloses a soil-free phase water-based drilling fluid, which uses starch microgel as a viscosity increasing and shear raising agent, uses polyanionic cellulose, sulfonated lignite resin and sulfomethyl phenolic aldehyde resin as filtration reducing agents, and uses polyethylene glycol as a anti-sloughing agent, and the temperature resistance is up to 150 DEG C. Chinese patent document CN108003848A discloses a supramolecular material viscosity increasing and shear raising agent and its application in soil-free phase water-based drilling fluid, and the drilling fluid has a temperature resistance up to 120 DEG C, and after aging at 120 DEG C, the AV is 49.0 mPa.s, the PV is 30.0 mPa.s, the YP is 19.0 Pa, and the FL HTHP(120℃、3.5MPa) is 8.4 mL. Chinese patent document CN109266316A discloses a soil-free phase water-based drilling fluid using calcium alginate microgel as a high-temperature resistant viscosity increasing and shear raising agent, which has a temperature resistance up to 160 DEG C and can resist 4% potassium chloride.

[0004] Although the above-mentioned soil-free phase water-based drilling fluid has good temperature resistance, it lacks salt resistance and cannot achieve the performance of resisting 180 DEG C and saturated salt. Therefore, it is urgent to develop a high-density soil-free phase water-based drilling fluid with a temperature resistance up to 180 DEG C and saturated salt resistance to provide technical support for the development of deep and ultra-deep oil and gas resources. SUMMARY

[0005] To address the shortcomings of existing technologies, especially the insufficient high-temperature and salt resistance of existing soilless water-based drilling fluids and the technical problem of rheological filtration failure under high-temperature (180℃) saturated salt (36% NaCl) conditions, this invention provides a soilless water-based drilling fluid resistant to 180℃ saturated salt, its preparation method, and its application.

[0006] The technical solution of the present invention is as follows:

[0007] A water-based drilling fluid resistant to 180℃ saturated salt and soil-free phase comprises the following raw materials in parts by weight: 100 parts water, 0.2-0.4 parts pH adjuster, 2-3 parts viscosity enhancer and filtration loss reducer, 1-5 parts high-temperature protectant, 3-6 parts clinoptilolite, 10-20 parts fly ash, 1-3 parts modified polyurethane fiber, 3-6 parts emulsified asphalt, and 1-2 parts lubricant RH-3.

[0008] According to a preferred embodiment of the present invention, the pH adjuster is sodium hydroxide and / or potassium hydroxide.

[0009] According to a preferred embodiment of the present invention, the thickening and filtration loss reducing agent is obtained by free radical polymerization of N,N-dimethylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and a rigid cyclic monomer; the mass ratio of N,N-dimethylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the rigid cyclic monomer is 15-25:5-10:4-8:1-3; the rigid cyclic monomer is N-vinylpyrrolidone, N-vinylcaprolactam or N-acrylomorpholine.

[0010] According to the present invention, the preparation method of the above-mentioned thickening and filtration loss reducing agent includes the following steps:

[0011] N,N-dimethylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and rigid cyclic monomers were added to deionized water and stirred until homogeneous to obtain a monomer solution. The monomer solution was heated to the reaction temperature, and then an initiator aqueous solution was added to initiate a free radical polymerization reaction. After the reaction was completed, the resulting gel was washed, dried and pulverized to obtain a thickening and filtration loss reducing agent.

[0012] According to a preferred embodiment of the present invention, in the preparation of the thickening and filtration loss reducing agent, the total mass ratio of N,N-dimethylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and rigid cyclic monomer to deionized water is 20-45:50-80.

[0013] According to the application, preferably, in the preparation of the viscosity increasing and fluid loss reducing agent, the initiator is 2,2'-azobisdimethylamino propane dihydrochloride, ammonium persulfate or potassium persulfate; the mass of the initiator is 0.05-0.1% of the total mass of N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and rigid cyclic monomer; the concentration of the aqueous solution of the initiator is 0.01-0.02 g / mL.

[0014] According to the application, preferably, in the preparation of the viscosity increasing and fluid loss reducing agent, the reaction temperature is 50-60℃, and the reaction time is 3-5 h; the reaction is carried out in a nitrogen atmosphere.

[0015] According to the application, preferably, in the preparation of the viscosity increasing and fluid loss reducing agent, the washing is carried out 2-3 times using ethanol, and the drying is carried out at 70-80℃ until constant weight.

[0016] According to the application, preferably, the high-temperature protective agent is branched polyethylene imine, the weight average molecular weight of the branched polyethylene imine is 10000-70000, and further preferably, the weight average molecular weight of the branched polyethylene imine is 10000; the branching degree of the branched polyethylene imine is 0.40-0.60, wherein the molar ratio of primary amine, secondary amine and tertiary amine groups is 20-40:30-40:30-40.

[0017] According to the application, preferably, the particle size of the clinoptilolite is 100-1250 mesh, and further preferably, 600 mesh.

[0018] According to the application, preferably, the particle size of the fly ash is 15-25 μm, and the fly ash is II or III grade fly ash.

[0019] According to the application, preferably, the modified polyurethane fiber is obtained by modifying polyurethane fiber using 1,3-propane sultone; preferably, the modified polyurethane fiber is prepared according to the following method:

[0020] (1) polyurethane fiber is added into ethanol, and after ultrasonic treatment, the pretreated polyurethane fiber is obtained by filtration, washing and drying;

[0021] (2) the pretreated polyurethane fiber is added into N,N-dimethyl formamide, and after ultrasonic treatment, 1,3-propane sultone is added for reaction; after the reaction is completed, the modified polyurethane fiber is obtained by filtration, washing and drying.

[0022] Preferably, in the preparation of the modified polyurethane fiber, the length of the polyurethane fiber in step (1) is 1-10 mm, and further preferably, 1-3 mm, and the diameter of the polyurethane fiber is 40-60 μm.

[0023] Preferably, in the preparation of the modified polyurethane fiber, the mass ratio of the polyurethane fiber to ethanol in step (1) is 1:20-50; and the ultrasonic treatment time is 5-10 min.

[0024] Preferably, in the preparation of the modified polyurethane fiber, the washing in step (1) is washing 2-5 times with deionized water, and the drying is vacuum drying at 55-60℃ for 20-25h.

[0025] Preferably, in the preparation of the modified polyurethane fiber, the mass ratio of the pretreated polyurethane fiber to N,N-dimethylformamide in step (2) is 1-3:15-25.

[0026] Preferably, in the preparation of the modified polyurethane fiber, the ultrasonic treatment time in step (2) is 5-10 min.

[0027] Preferably, in the preparation of the modified polyurethane fiber, the mass ratio of 1,3-propanesultone to pretreated polyurethane fiber in step (2) is 0.5-2:1-3.

[0028] Preferably, in the preparation of the modified polyurethane fiber, the reaction temperature in step (2) is 50-80℃, and the reaction time is 10-16h.

[0029] Preferably, in the preparation of the modified polyurethane fiber, the washing in step (2) is washing 2-4 times with methanol or ethanol, and then washing with deionized water until the washing liquid is neutral; and the drying is vacuum drying at 55-60℃ for 20-25h.

[0030] According to the present application, the emulsified asphalt comprises the following raw materials in mass fraction: water 70-100 parts, petroleum asphalt 60-80 parts, cetyltrimethylammonium chloride 1-3 parts, sodium dodecylbenzenesulfonate 0.5-2 parts, and acetic acid 1-2 parts.

[0031] The preparation method of the above-mentioned anti-180℃ saturated salt soil-free water-based drilling fluid comprises the following steps:

[0032] The pH regulator, clinoptilolite, viscosity increasing and filtration reducing agent, high temperature protective agent, fly ash, modified polyurethane fiber, emulsified asphalt, and lubricant RH-3 are sequentially added into water and stirred uniformly to obtain the anti-180℃ saturated salt soil-free water-based drilling fluid.

[0033] Preferably, after adding the pH regulator, stirring is carried out at a speed of 1000-2000 rpm for 5-10 minutes; after adding the clinoptilolite, stirring is carried out at a speed of 1000-2000 rpm for 5-10 minutes; after adding the viscosity increasing and filtration reducing agent, stirring is carried out at a speed of 10000-12000 rpm for 15-30 minutes; after adding the high temperature protection agent, stirring is carried out at a speed of 5000-6000 rpm for 10-15 minutes; after adding the fly ash, stirring is carried out at a speed of 5000-6000 rpm for 10-15 minutes; after adding the modified polyurethane fiber, stirring is carried out at a speed of 5000-6000 rpm for 10-15 minutes; after adding the emulsified asphalt, stirring is carried out at a speed of 5000-6000 rpm for 10-15 minutes; and after adding the lubricant RH-3, stirring is carried out at a speed of 5000-6000 rpm for 10-15 minutes.

[0034] According to the application, the above-mentioned anti-180℃ saturated salt soil-free phase water-based drilling fluid is used in deep layer and super deep layer stratum oil and gas drilling engineering to efficiently suspend and carry cuttings, clean the bottom of the well, form a dense mud cake to reduce the filtration loss, enhance the well wall stability, and guarantee the safety and efficiency of deep layer drilling.

[0035] The "parts" in the application are mass parts unless otherwise specified.

[0036] The technical features and beneficial effects of the application are as follows:

[0037] 1. The viscosity increasing and filtration reducing agent in the application is polymerized from N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and a rigid cyclic monomer. N,N-dimethyl acrylamide and acrylamide are easy to polymerize with other olefin monomers, and can synthesize a polymer with high molecular weight. N,N-dimethyl acrylamide serves as the polymer main chain, and the rigid cyclic monomer serves as the polymer side chain, which significantly enhances the temperature resistance of the polymer. The zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide endows the polymer with a counter polyelectrolyte effect, so that the polymer fully stretches under high salt conditions. The synergistic effect of dimethyl, rigid ring and betaine side chain makes the viscosity increasing and filtration reducing agent of the application have excellent temperature resistance and salt tolerance, so that it can still effectively improve the viscosity and shear force of the drilling fluid under high temperature and high salt conditions, and reduce the filtration loss when matched with a plugging agent.

[0038] 2、The branched polyethylene imine is used as a protective agent in the application, and the cross-linking of the imine group and the amide group of the tackifying fluid loss additive is realized through the transamidation reaction, so that the cross-linked polymer with a three-dimensional network structure is formed, the performance failure of the tackifying fluid loss additive under the high temperature and high salt conditions caused by the hydrolysis is effectively prevented, the performance of the tackifying fluid loss additive under the high temperature is maintained, and the performance of the soil-free water-based drilling fluid under the high temperature and high salt conditions is further maintained.

[0039] 3、The fly ash, the modified polyurethane fiber and the emulsified asphalt are compounded to effectively plug, prevent collapse and reduce fluid loss. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The infrared spectrum of the tackifying fluid loss additive prepared in Preparation Example 1.

[0041] Figure 2 The actual photo of the anti-180 DEG C saturated salt soil-free water-based drilling fluid prepared in Example 1. DETAILED DESCRIPTION

[0042] The specific embodiments of the application are further described below. According to the following examples, the application can be better understood. However, it will be readily apparent to those skilled in the art that specific materials, conditions and procedures described in the examples are for the purpose of illustration only and are not intended to limit the application as described in the following claims.

[0043] In the following examples and comparative examples, the materials used are commercially available, and the methods used are conventional methods in the art, unless otherwise specified.

[0044] The weight average molecular weight of the branched polyethylene imine used in the examples and comparative examples is 10000, the branching degree of the branched polyethylene imine is 0.60, and the molar ratio of the primary amine, the secondary amine and the tertiary amine groups is 30:30:40.

[0045] The particle size of the clinoptilolite is 600 mesh.

[0046] The average particle size of the fly ash is 20 microns, and the fly ash is II grade fly ash.

[0047] Emulsified asphalt comprises the following raw materials in parts by weight: 80 parts water, 70 parts petroleum asphalt, 3 parts cetyltrimethylammonium chloride, 1 part sodium dodecylbenzenesulfonate, and 2 parts acetic acid.

[0048] The thickening and filtration loss reducing agent was prepared according to Preparation Example 1, Preparation Example 2, and Preparation Example 3, respectively, and the modified polyurethane fiber was prepared according to Preparation Example 4.

[0049] Preparation Example 1

[0050] The preparation method of the thickening and filtration loss reducing agent includes the following steps:

[0051] Add 80g of deionized water to a clean three-necked flask, then add 15.0g of N,N-dimethylacrylamide, 10.0g of acrylamide, 4.0g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide, and 3.0g of 4-acryloylmorpholine in sequence. Stir continuously at 400 rpm for 10 minutes to disperse the monomers evenly, obtaining a monomer solution. Heat the monomer solution to 55°C, and add an initiator aqueous solution (0.025g of 2,2'-azobisisobutylamidine dihydrochloride dissolved in 2mL of deionized water) dropwise under a nitrogen atmosphere to initiate free radical polymerization at a dropping rate of 2 drops / s. After the addition is complete, continue the reaction at 55°C under a nitrogen atmosphere for 4 hours to obtain a gel. Wash the obtained gel twice with anhydrous ethanol, dry it at 80°C to constant weight, and pulverize it to obtain thickening and filtration loss reducing agent A1.

[0052] The infrared spectrum of the thickening and filtration loss reducing agent obtained in this preparation example is as follows: Figure 1 As shown, it is located at 3385cm. -1 3201cm -1 The characteristic peak at 2968 cm⁻¹ originates from the asymmetric and symmetric stretching vibrations of the NH bond in the amide group; -1 The characteristic peak at 2924 cm⁻¹ originates from the antisymmetric stretching vibration of the CH bond in the methyl group. -1 The characteristic peak at 2860 cm⁻¹ originates from the antisymmetric stretching vibration of the CH bond in the methylene group. -1 The characteristic peak at 1726 cm⁻¹ originates from the stretching vibration of the CH bond in the methyl and methylene groups; -1 The characteristic peak at 1650 cm⁻¹ originates from the stretching vibration of the C=O group in the ester group; -1 The characteristic peak at 1610 cm⁻¹ originates from the stretching vibration of C=O in the amide group and the acryloylmorpholine side group; -1 The characteristic peak at 1417 cm⁻¹ originates from the bending vibration of the NH group in the amide group. -1 The characteristic peak at 1368 cm⁻¹ originates from the stretching vibration of quaternary ammonium cations. -1 1240cm -1and 1039 cm -1 characteristic peaks at 1273 m -1 characteristic peaks at 1114 cm -1 characteristic peaks at 626 cm -1 characteristic peaks at 626 cm

[0053] Preparation Example 2

[0054] The method for preparing the viscosity-reducing fluid loss additive comprises the following steps:

[0055] A clean three-necked flask was charged with 80 g of deionized water, followed by 25.0 g of N,N-dimethylacrylamide, 10.0 g of acrylamide, 6.0 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and 2.0 g of 4-acryloylmorpholine. The monomers were uniformly dispersed by stirring at a rate of 400 rpm for 10 min to obtain a monomer solution. The monomer solution was heated to 55°C, and an aqueous initiator solution (0.025 g of 2,2'-azobis(isobutyryl amide) dihydrochloride dissolved in 2 mL of deionized water) was added dropwise under a nitrogen atmosphere to initiate free radical polymerization. The dropwise addition was performed at a rate of 2 drops / s. After the dropwise addition was completed, the reaction was continued at 55°C under a nitrogen atmosphere for 4 h to obtain a gel. The obtained gel was washed twice with anhydrous ethanol and dried at 80°C until the weight was constant. After being crushed, a viscosity-reducing fluid loss additive A2 was obtained.

[0056] Preparation Example 3

[0057] The method for preparing the viscosity-reducing fluid loss additive comprises the following steps:

[0058] Into a clean three-necked flask, 80 g of deionized water was added, followed by 20.0 g of N,N-dimethylacrylamide, 8.0 g of acrylamide, 8.0 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, 3.0 g of 4-acryloylmorpholine, and 3.0 g of 2-[[2-(methacryloyloxy)ethyl]dimethylammonio] acetate, and the monomers were uniformly dispersed by stirring at a rate of 400 rpm for 10 minutes to obtain a monomer solution. The monomer solution was heated to 55°C, and an aqueous initiator solution (0.025 g of 2,2'-azobis(isobutyryl amide) dihydrochloride dissolved in 2 mL of deionized water) was added dropwise under a nitrogen atmosphere to initiate radical polymerization at a rate of 2 drops / s. After the dropwise addition was completed, the reaction was continued at 55°C under a nitrogen atmosphere for 4 h to obtain a gel. The obtained gel was washed twice with anhydrous ethanol and dried at 80°C until the weight was constant. After being pulverized, a viscosity-reducing and filtration-reducing agent A3 was obtained.

[0059] Comparative Preparation Example 1

[0060] The viscosity-reducing and filtration-reducing agent was prepared according to the method described in Preparation Example 1, except that [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide was not added, to obtain a viscosity-reducing and filtration-reducing agent D1.

[0061] Comparative Preparation Example 2

[0062] The viscosity-reducing and filtration-reducing agent was prepared according to the method described in Preparation Example 1, except that 4-acryloylmorpholine was not added, to obtain a viscosity-reducing and filtration-reducing agent D2.

[0063] Comparative Preparation Example 3

[0064] The viscosity-reducing and filtration-reducing agent was prepared according to the method described in Preparation Example 1, except that acrylamide was not added, to obtain a viscosity-reducing and filtration-reducing agent D3.

[0065] Comparative Preparation Example 4

[0066] The viscosity-reducing and filtration-reducing agent was prepared according to the method described in Preparation Example 1, except that N,N-dimethylacrylamide was replaced by diacetone acrylamide, to obtain a viscosity-reducing and filtration-reducing agent D4.

[0067] Comparative Preparation Example 5

[0068] The viscosity-reducing and filtration-reducing agent was prepared according to the method described in Preparation Example 1, except that [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide was replaced by 2-[[2-(methacryloyloxy)ethyl]dimethylammonio] acetate, to obtain a viscosity-reducing and filtration-reducing agent D5.

[0069] Preparation Example 4

[0070] The method for preparing a modified polyurethane fiber includes the following steps:

[0071] Preparation of modified polyurethane fiber: 5.0 g of polyurethane fiber (length 1-3 mm, diameter 40-60 μm) was added to 150 mL of ethanol, and cleaned by ultrasonic for 5 min to remove the surface oil and impurities, then filtered, and the obtained precipitate was washed with deionized water for 3 times, then dried at 60 °C under vacuum for 24 h to obtain pretreated polyurethane fiber, which was cooled to room temperature and used as needed; 4 g of the pretreated polyurethane fiber was placed in a dry three-necked flask, 80.0 g of DMF was added, and the polyurethane fiber was swelled by ultrasonic for 10 min, 3.0 g of 1,3-propanesultone was added under stirring, and the reaction was carried out at 65 °C for 12 h; after the reaction was completed, it was naturally cooled to room temperature, filtered, and the obtained solid was washed with ethanol for 3 times, then washed repeatedly with deionized water until the washing liquid was neutral, and the obtained solid was dried at 60 °C under vacuum for 24 h to obtain yellowish modified polyurethane fiber.

[0072] Example 1

[0073] A 180 °C saturated salt soilless phase water-based drilling fluid, comprising the following raw materials in mass fraction: water 100 parts, pH regulator 0.2 parts, viscosity increasing and filtration reducing agent 3 parts, high temperature protective agent 5 parts, clinoptilolite 6 parts, fly ash 20 parts, modified polyurethane fiber 3 parts, emulsified asphalt 6 parts, lubricant RH-3 2 parts.

[0074] The pH regulator is sodium hydroxide; the viscosity increasing and filtration reducing agent is the viscosity increasing and filtration reducing agent A1 prepared in Preparation Example 1; and the high temperature protective agent is branched polyethylene imine.

[0075] The preparation method of the above-mentioned 180 °C saturated salt soilless phase water-based drilling fluid, comprising the following steps:

[0076] The water was added to a clean slurry cup, the pH regulator was added, and stirred at a rate of 2000 rpm for 5 min; the clinoptilolite was added, and stirred at a rate of 2000 rpm for 5 min; the viscosity increasing and filtration reducing agent was added, and stirred at a rate of 12000 rpm for 20 min; the high temperature protective agent was added, and stirred at a rate of 6000 rpm for 10 min; the fly ash was added, and stirred at a rate of 6000 rpm for 10 min; the modified polyurethane fiber was added, and stirred at a rate of 6000 rpm for 10 min; the emulsified asphalt was added, and stirred at a rate of 6000 rpm for 10 min; the lubricant RH-3 was added, and stirred at a rate of 6000 rpm for 10 min, to obtain the 180 °C saturated salt soilless phase water-based drilling fluid F1.

[0077] The actual photo of the 180 °C saturated salt soilless phase water-based drilling fluid obtained in this example is shown in Figure 2 .

[0078] Example 2

[0079] The application discloses a 180 DEG C saturated salt resistant soil-free water-based drilling fluid, which comprises the following raw materials in mass fractions: 100 parts of water, 0.2 parts of a pH regulator, 3 parts of a viscosity increasing and filtration reducing agent, 3 parts of a high-temperature protective agent, 3 parts of clinoptilolite, 15 parts of fly ash, 3 parts of modified polyurethane fiber, 6 parts of emulsified asphalt and 2 parts of lubricant RH-3.

[0080] Other raw material categories and the preparation method of the drilling fluid are the same as those in the example 1, and the 180 DEG C saturated salt resistant soil-free water-based drilling fluid F2 is prepared.

[0081] Example 3

[0082] The application discloses a 180 DEG C saturated salt resistant soil-free water-based drilling fluid, which comprises the following raw materials in mass fractions: 100 parts of water, 0.2 parts of a pH regulator, 3 parts of a viscosity increasing and filtration reducing agent, 3 parts of a high-temperature protective agent, 3 parts of clinoptilolite, 15 parts of fly ash, 3 parts of modified polyurethane fiber, 6 parts of emulsified asphalt and 2 parts of lubricant RH-3.

[0083] Other raw material categories and the preparation method of the drilling fluid are the same as those in the example 1, and the 180 DEG C saturated salt resistant soil-free water-based drilling fluid F2 is prepared.

[0084] Example 4

[0085] The application discloses a 180 DEG C saturated salt resistant soil-free water-based drilling fluid, which comprises the following raw materials in mass fractions: 100 parts of water, 0.2 parts of a pH regulator, 3 parts of a viscosity increasing and filtration reducing agent, 3 parts of a high-temperature protective agent, 3 parts of clinoptilolite, 15 parts of fly ash, 3 parts of modified polyurethane fiber, 6 parts of emulsified asphalt and 2 parts of lubricant RH-3.

[0086] Other raw material categories and the preparation method of the drilling fluid are the same as those in the example 1, and the 180 DEG C saturated salt resistant soil-free water-based drilling fluid F2 is prepared.

[0087] Example 5

[0088] The application discloses a 180 DEG C saturated salt resistant soil-free water-based drilling fluid, which comprises the following raw materials in mass fractions: 100 parts of water, 0.2 parts of a pH regulator, 3 parts of a viscosity increasing and filtration reducing agent, 3 parts of a high-temperature protective agent, 3 parts of clinoptilolite, 15 parts of fly ash, 3 parts of modified polyurethane fiber, 6 parts of emulsified asphalt and 2 parts of lubricant RH-3.

[0089] Other raw material categories and the preparation method of the drilling fluid are the same as those in the example 1, and the 180 DEG C saturated salt resistant soil-free water-based drilling fluid F2 is prepared.

[0090] Example 6

[0091] A 180°C saturated salt clay-free water-based drilling fluid was prepared as described in Example 1, except that the viscosity and fluid loss reducing agent was the viscosity and fluid loss reducing agent A2 prepared in Preparation Example 2, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a 180°C saturated salt clay-free water-based drilling fluid F6.

[0092] Example 7

[0093] A 180°C saturated salt clay-free water-based drilling fluid was prepared as described in Example 1, except that the viscosity and fluid loss reducing agent was the viscosity and fluid loss reducing agent A3 prepared in Preparation Example 3, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a 180°C saturated salt clay-free water-based drilling fluid F7.

[0094] Comparative Example 1

[0095] A clay-free water-based drilling fluid was prepared as described in Example 1, except that the viscosity and fluid loss reducing agent was the viscosity and fluid loss reducing agent Dl prepared in Comparative Preparation Example 1, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a clay-free water-based drilling fluid DF1.

[0096] Comparative Example 2

[0097] A clay-free water-based drilling fluid was prepared as described in Example 1, except that the viscosity and fluid loss reducing agent was the viscosity and fluid loss reducing agent D2 prepared in Comparative Preparation Example 2, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a clay-free water-based drilling fluid DF2.

[0098] Comparative Example 3

[0099] A clay-free water-based drilling fluid was prepared as described in Example 1, except that the viscosity and fluid loss reducing agent was the viscosity and fluid loss reducing agent D3 prepared in Comparative Preparation Example 3, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a clay-free water-based drilling fluid DF3.

[0100] Comparative Example 4

[0101] A clay-free water-based drilling fluid was prepared as described in Example 1, except that the clinoptilolite was not added, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a clay-free water-based drilling fluid DF4.

[0102] Comparative Example 5

[0103] A clay-free water-based drilling fluid was prepared as described in Example 1, except that the modified polyurethane fiber was not added, and the other raw material kinds and the method of preparing the drilling fluid were the same as in Example 1, to thereby produce a clay-free water-based drilling fluid DF5.

[0104] Comparative Example 6

[0105] A soilless phase water-based drilling fluid was prepared according to the method described in Example 1, except that no emulsified asphalt was added, and the other raw material types and the preparation method of the drilling fluid were the same as in Example 1, to obtain a soilless phase water-based drilling fluid DF6.

[0106] Comparative Example 7

[0107] A soilless phase water-based drilling fluid was prepared according to the method described in Example 1, except that no high-temperature protective agent was added, and the other raw material types and the preparation method of the drilling fluid were the same as in Example 1, to obtain a soilless phase water-based drilling fluid DF7.

[0108] Comparative Example 8

[0109] A soilless phase water-based drilling fluid was prepared according to the method described in Example 1, except that no fly ash was added, and the other raw material types and the preparation method of the drilling fluid were the same as in Example 1, to obtain a soilless phase water-based drilling fluid DF8.

[0110] Comparative Example 9

[0111] A soilless phase water-based drilling fluid was prepared according to the method described in Example 1, except that the viscosity and fluid loss reducer was the viscosity and fluid loss reducer D4 prepared in Comparative Preparation Example 4, and the other raw material types and the preparation method of the drilling fluid were the same as in Example 1, to obtain a soilless phase water-based drilling fluid DF9.

[0112] Comparative Example 10

[0113] A soilless phase water-based drilling fluid was prepared according to the method described in Example 1, except that the viscosity and fluid loss reducer was the viscosity and fluid loss reducer D5 prepared in Comparative Preparation Example 5, and the other raw material types and the preparation method of the drilling fluid were the same as in Example 1, to obtain a soilless phase water-based drilling fluid DF10.

[0114] Test Example 1

[0115] To 400 g of the drilling fluid of the examples and comparative examples, 144.0 g of NaCl was added respectively to prepare a soilless phase saturated salt water-based drilling fluid. The drilling fluid was loaded into a stainless steel aging tank and rolled at a constant temperature of 180℃ for 16 hours. After aging, the drilling fluid was cooled to room temperature and taken out, and stirred at 6000 rpm for 20 min. The apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API fluid loss FL API and high-temperature and high-pressure fluid loss FL HTHP(180℃、3.5MPa) of the drilling fluid before and after high-temperature aging were determined according to the Oil and Natural Gas Industry Standard GB / T 29170-2012 “Oil and Natural Gas Industry-Drilling Fluid Laboratory Test”, and the results are shown in Tables 1-2.

[0116] Table 1 Performance test of drilling fluid of examples

[0117]

[0118] Table 2 Performance test of drilling fluid of comparative example

[0119]

[0120] From the experimental results of Tables 1-2, it can be seen that the soil-free water-based drilling fluids F1-F7 of the embodiments of the present application have good rheological and filtration properties before and after aging at 180℃ under saturated salt conditions. From the experimental data of the comparative example, it can be seen that when the viscosity-increasing and filtration-reducing agent lacks a zwitterionic monomer or a rigid cyclic monomer, the salt tolerance of the treating agent decreases, and the viscosity-increasing and filtration-reducing properties under the conditions of 180℃ and saturated salt decrease. In the present application, the viscosity-increasing and filtration-reducing agent lacks an amide group, and thus cannot form a crosslinked structure with the high-temperature protective agent, and cannot effectively increase the viscosity and reduce the filtration. If the drilling fluid lacks clinoptilolite, the network structure formed by the viscosity-increasing and filtration-reducing agent and the clinoptilolite in the system becomes weak, and the rheological and filtration properties also become poor. The same applies to the lack of other plugging materials, such as the lack of fly ash, modified polyurethane fiber or emulsified asphalt, which can cause the plugging performance of the drilling fluid to decrease and the filtration loss to increase. In addition, if the high-temperature protective agent is lacking, the viscosity-increasing and filtration-reducing agent cannot be prevented from degrading at high temperatures, and the AV, PV and YP of the drilling fluid after aging decrease significantly, and the filtration loss increases.

[0121] Test Example 2

[0122] 400g of the drilling fluid F1 of Example 1 was added with 144.0g of NaCl, and then 0g, 100g, 250g, 420.0g and 560.0g of 300-mesh barite (p=4.3g / cm 3 ) was added, respectively, to adjust the density to 1.21, 1.40, 1.60, 1.80 and 2.00g / cm 3 , respectively, to prepare saturated salt high-density soil-free water-based drilling fluids. The above drilling fluids were loaded into stainless steel aging tanks and rolled at 180℃ for 16 hours. After aging, the drilling fluids were cooled to room temperature and taken out, and stirred at 6000rpm for 20min. The apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API filtration loss FL API and high-temperature high-pressure filtration loss FL HTHP(180℃、3.5MPa) of the drilling fluids before and after high-temperature aging were determined according to the standard GB / T 29170-2012 “Oil and gas industry-Drilling fluid laboratory test”, and the results are shown in Table 3.

[0123] Table 3 Performance test of drilling fluid

[0124]

[0125] From the experimental results of Table 3, it can be seen that the drilling fluid of the present application Example 1 has reasonable rheological and filtration properties after aging at 180℃ in the density range of 1.21 to 2.0 g / cm 3 When the drilling fluid density is 2.0 g / cm 3 , the AV before and after aging is 122.5 and 102.5 mPa·s respectively, and the apparent viscosity maintenance rate is 83.67%. The FL API is 0.2 and 1.8 mL respectively, and the FL HTHP(180℃、3.5MPa) is 24.0 mL. It shows that the soil-free water-based drilling fluid of the present application has good rheological and filtration properties under the conditions of high temperature, high salt and high density.

[0126] Test Example 3

[0127] To 400 g of the drilling fluid F1 of Example 1, 144.0 g of NaCl is added, and then 250 g of barite is added to adjust the drilling fluid density to 1.60 g / cm 3 , to prepare a saturated salt high-density soil-free water-based drilling fluid. The above drilling fluid is loaded into a stainless steel aging tank, and is continuously rolled at 180℃ for 24 h, 72 h, 120 h and 168 h, and after aging, it is cooled to room temperature and taken out, and is stirred at 6000 rpm for 20 min. The apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API filtration loss FL API and high temperature and high pressure filtration loss FL HTHP(180℃、3.5MPa) of the drilling fluid before and after high temperature aging are determined according to the oil and gas industry standard GB / T 29170-2012 “Oil and gas industry-Drilling fluid laboratory test”, and the results are shown in Table 4.

[0128] Table 4 Performance of the drilling fluid after long-term aging

[0129]

[0130] From Table 4, it can be seen that when the drilling fluid F1 of the present application Example 1 is saturated with salt and 1.60 g / cm 3 after 24 h, 72 h, 120 h and 168 h respectively, the PV is 49.0, 47.5, 38.5 and 30.0 mPa·s respectively, and the PV maintenance rate is 73.13%, 70.90%, 57.46% and 44.78% respectively, all of which are greater than 40%. The FL API is 0.2, 0.6, 1.2, 1.8 and 2.2 mL respectively, and the FL HTHP(190℃、3.5MPa) is 18.8, 22.4, 25.6 and 28.8 mL respectively, all of which are less than 30.0 mL. It shows that the drilling fluid F1 of the present application can maintain viscosity and low filtration loss after long-term aging, and has good long-term high temperature stability.

[0131] In summary, the soilless phase water-based drilling fluid of the present application can be configured into saturated salt drilling fluid, which can be weighted to 2.0g / cm 3 The soilless phase water-based drilling fluid of the present application has good stability after aging for 7 days at 180℃. The synergistic effect of the thickening and fluid loss reducing agent, high temperature protective agent, micro-nano particles and modified polyurethane fiber in the soilless phase water-based drilling fluid of the present application makes the drilling fluid have good rheological properties and fluid loss properties at 180℃, saturated salt and 2.0g / cm 3 density, and can overcome the technical problem of performance failure of the drilling fluid in deep salt and gypsum complex formations.

[0132] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0133] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0134] Furthermore, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the technical concept of the present application, and it should be considered as disclosed content of the present application.

Claims

1. An anti-180°C saturated salt free aqueous base drilling fluid, characterized in that, The raw materials include the following mass fractions: water 100 parts, pH regulator 0.2-0.4 parts, viscosity increasing and filtration reducing agent 2-3 parts, high temperature protection agent 1-5 parts, clinoptilolite 3-6 parts, fly ash 10-20 parts, modified polyurethane fiber 1-3 parts, emulsified asphalt 3-6 parts, and lubricant RH-3 1-2 parts; The pH regulator is sodium hydroxide and / or potassium hydroxide; The viscosity increasing and filtration reducing agent is obtained by free radical polymerization of N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and a rigid cyclic monomer; the rigid cyclic monomer is N-vinyl pyrrolidone, N-vinyl caprolactam or N-acryloyl morpholine; the mass ratio of N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and the rigid cyclic monomer is 15-25:5-10:4-8:1-3; The high temperature protection agent is branched polyethylene imine; The modified polyurethane fiber is obtained by modifying polyurethane fiber with 1,3-propanesulfonic acid lactone.

2. The 180°C saturated salt-free aqueous-based drilling fluid of claim 1, wherein, The preparation method of the viscosity increasing and filtration reducing agent comprises the following steps: adding N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and a rigid cyclic monomer into deionized water, stirring uniformly to obtain a monomer solution; heating the monomer solution to a reaction temperature, then adding an initiator aqueous solution to initiate a free radical polymerization reaction; after the reaction is completed, the obtained gel is washed, dried, and crushed to obtain the viscosity increasing and filtration reducing agent.

3. The 180°C saturated salt-free aqueous-based drilling fluid of claim 2, wherein, In the preparation of the viscosity increasing and filtration reducing agent, the total mass of N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and the rigid cyclic monomer and the mass of deionized water are in the ratio of 20-45:50-80; The initiator is 2,2'-azobisdimethylamidinum dihydrochloride, ammonium persulfate or potassium persulfate; the mass of the initiator is 0.05-0.1% of the total mass of N,N-dimethyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and the rigid cyclic monomer; the concentration of the initiator aqueous solution is 0.01-0.02 g / mL; The reaction temperature is 50-60℃, the reaction time is 3-5 h; the reaction is carried out in a nitrogen atmosphere; the washing is carried out 2-3 times using ethanol, and the drying is carried out at 70-80℃ until the weight is constant.

4. The 180°C saturated salt-free aqueous-based drilling fluid of claim 1, wherein, The weight average molecular weight of the branched polyethylene imine is 10000-70000, and the branching degree of the branched polyethylene imine is 0.40-0.60, wherein the molar ratio of primary amine, secondary amine and tertiary amine groups is 20-40:30-40:30-40; The particle size of the clinoptilolite is 100-1250 mesh; the particle size of the fly ash is 15-25 μm, and the fly ash is II or III grade fly ash.

5. The 180°C saturated salt-free aqueous-based drilling fluid of claim 1, wherein, The modified polyurethane fiber is prepared by the following method: (1) adding polyurethane fiber into ethanol, and after ultrasonic treatment, filtering, washing and drying, pretreated polyurethane fiber is obtained; (2) adding the pretreated polyurethane fiber into N,N-dimethylformamide, and after ultrasonic treatment, adding 1,3-propanesultone, and reacting; after the reaction is completed, filtering, washing and drying, the modified polyurethane fiber is obtained.

6. The 180°C saturated salt-free aqueous-based drilling fluid of claim 5, wherein, In the preparation of the modified polyurethane fiber, the length of the polyurethane fiber in step (1) is 1-10 mm, the diameter of the polyurethane fiber is 40-60 μm; the mass ratio of the polyurethane fiber to ethanol is 1:20-50; the ultrasonic treatment time is 5-10 min; the washing is washing 2-5 times with deionized water, and the drying is vacuum drying at 55-60 ℃ for 20-25 h; In step (2), the mass ratio of the pretreated polyurethane fiber to N,N-dimethylformamide is 1-3:15-25; the ultrasonic treatment time is 5-10 min; the mass ratio of 1,3-propanesultone to the pretreated polyurethane fiber is 0.5-2:1-3; the reaction temperature is 50-80 ℃, and the reaction time is 10-16 h; the washing is washing 2-4 times with methanol or ethanol, and then washing with deionized water until the washing liquid is neutral; the drying is vacuum drying at 55-60 ℃ for 20-25 h.

7. The 180°C saturated salt-free aqueous-based drilling fluid of claim 1, wherein, The emulsified asphalt comprises the following raw materials in mass fraction: water 70-100 parts, petroleum asphalt 60-80 parts, hexadecyl trimethyl ammonium chloride 1-3 parts, sodium dodecyl benzene sulfonate 0.5-2 parts, and acetic acid 1-2 parts.

8. A method of preparing the anti-180°C saturated salt soil-free phase water-based drilling fluid according to any one of claims 1-7, characterized in that, The method comprises the following steps: The pH adjusting agent, clinoptilolite, viscosity increasing and filtration reducing agent, high temperature protective agent, fly ash, modified polyurethane fiber, emulsified asphalt and lubricant RH-3 are sequentially added into water, and stirred uniformly to obtain the anti-180 ℃ saturated salt soil-free phase water-based drilling fluid.

9. The method for preparing the 180℃ resistant saturated salt water-based drilling fluid without soil phase according to claim 8, characterized in that, After adding the pH adjusting agent, stirring at a speed of 1000-2000 rpm for 5-10 min; after adding the clinoptilolite, stirring at a speed of 1000-2000 rpm for 5-10 min; after adding the viscosity increasing and filtration reducing agent, stirring at a speed of 10000-12000 rpm for 15-30 min; after adding the high temperature protective agent, stirring at a speed of 5000-6000 rpm for 10-15 min; after adding the fly ash, stirring at a speed of 5000-6000 rpm for 10-15 min; after adding the modified polyurethane fiber, stirring at a speed of 5000-6000 rpm for 10-15 min; after adding the emulsified asphalt, stirring at a speed of 5000-6000 rpm for 10-15 min; and after adding the lubricant RH-3, stirring at a speed of 5000-6000 rpm for 10-15 min.

10. Use of the anti-180°C saturated salt free aqueous drilling fluid according to any one of claims 1 to 7 in deep and ultra-deep formation oil and gas drilling operations, characterized in that, The depth of the deep and ultra-deep formation is 4500-6000 m.

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