Compound, preparation method, filtrate reducer and application

Abstract

The invention belongs to the technical field of drilling fluid, and particularly relates to a compound, a preparation method, a filtrate reducer and application. A compound comprising a structural unit derived from a monomer A, a structural unit derived from a monomer B, a structural unit derived from a monomer C, and a structural unit derived from a monomer D; the monomer A is hydrophobic nano silicon dioxide; the monomer B is selected from one or more of monomers shown in a formula I: # imgabs0 #, in the formula I, R1 and R2 are respectively and independently selected from hydrogen or C1-C10 alkyl; the monomer C is selected from one or more of monomers as shown in a formula II: # imgabs 1 #; in the formula II, R3, R4, R5 and R6 are respectively and independently selected from hydrogen or C1-C10 alkyl; the monomer D is selected from one or more of monomers shown in a formula III; in the formula II, R7, R8 and R9 are respectively and independently selected from hydrogen, straight chain alkyl of C1 to C10, branched chain alkyl of C3 to C10 or naphthenic base of C3 to C10. Comprising the compound provided by the invention has great application potential in high-temperature, high-salt and high-calcium stratums.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling fluids, and specifically relates to a compound, a preparation method, a filtration reducer, and an application thereof. Background Art

[0002] As an indispensable part of the drilling engineering, drilling fluids can provide many functions such as suspending drill cuttings, cooling the drill bit, and providing wellbore stability to enable the smooth progress of drilling operations. Drilling fluids have a very important property that they can form a filter cake during the drilling process, thus playing a role in protecting the wellbore. A thick filter cake leads to an increase in the filtration loss, while reducing the wellbore diameter, increasing the torque, causing differential sticking, and delaying the progress of the drilling project. Therefore, a thin and dense filter cake and a low filtration loss are the goals that drilling practitioners have been pursuing. As one of the main components of drilling fluids, the main function of filtration reducers is to adsorb on bentonite particles, provide a thin and dense filter cake, reduce the filtration loss of drilling fluids, maintain the stability of the wellbore, and avoid phenomena such as differential sticking. Nowadays, with the increasing development of deep wells, due to the existence of the geothermal gradient, a deeper well depth means a higher bottom hole temperature, which puts more stringent requirements on the temperature resistance of drilling fluid filtration reducers.

[0003] Currently, common filtration reducers for drilling fluids include sulfonated lignite, carboxymethyl cellulose, hydrolyzed polyacrylonitrile, acrylamide polymers, etc. The above filtration reducers have disadvantages such as a large dosage, single function, weak temperature and salt resistance, and large environmental pollution. For example, a salt and temperature resistant composite filtration reducer for drilling fluids and its preparation method mentioned in the patent document with the publication number CN115340853A adds sulfonated materials and multi - polymers, and has good temperature and salt resistance. However, with the increasingly strict environmental requirements, due to the pollution of sulfonated materials to the environment, they have been prohibited from use in most oil fields. And with nanoparticles as new materials, they have gradually been applied to the oil and gas industry to improve the performance of drilling fluid filtration reducers. Therefore, it is very urgent to develop a nano - graft copolymer filtration reducer with good temperature resistance, good salt and calcium resistance. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present invention provides a compound, a preparation method, a filtration reducer, and an application thereof.

[0005] In a first aspect, the present invention provides a compound. The compound comprises structural units derived from monomer A, structural units derived from monomer B, structural units derived from monomer C, and structural units derived from monomer D;

[0006] Monomer A is hydrophobic nano - silica;

[0007] Monomer B is selected from one or more of the monomers shown in Formula I:

[0008]

[0009] In formula I, R1 and R2 are each independently selected from hydrogen or a C1-C 10 alkyl group;

[0010] Monomer C is selected from one or more of the monomers represented by formula II:

[0011]

[0012] In formula II, R3, R4, R5, and R6 are each independently selected from hydrogen or a C1-C 10 alkyl group;

[0013] Monomer D is selected from one or more of the monomers represented by formula III:

[0014]

[0015] In formula III, R7, R8, and R9 are each independently selected from hydrogen, a C1-C 10 linear alkyl group, a C3-C 10 branched alkyl group, or a C3-C 10 cycloalkyl group.

[0016] That is, the compound in the present invention is obtained by polymerizing monomer A, monomer B, monomer C, and monomer D.

[0017] As a specific embodiment of the present invention, the compound in the present invention, by weight, comprises: 1 to 99 parts of monomer A, 0.1 to 98 parts of monomer B, 0.01 to 30 parts of monomer C, and 0.001 to 16 parts of monomer D.

[0018] Preferably, the compound in the present invention, by weight, comprises: 5 to 50 parts of monomer A, 1 to 60 parts of monomer B, 0.1 to 20 parts of monomer C, and 0.01 to 15 parts of monomer D.

[0019] More preferably, the compound in the present invention, by weight, comprises: 20 to 40 parts by weight of monomer A, 15 to 50 parts by weight of monomer B, 1 to 15 parts by weight of monomer C, and 0.1 to 10 parts by weight of monomer D.

[0020] As a specific embodiment of the present invention, the mass ratio of monomer A to monomer B is 1 to 2.

[0021] As a specific embodiment of the present invention, the hydrophobic nano-silica is nano-silica modified with a silane coupling agent.

[0022] Preferably, the particle size of the nano-silica modified with a silane coupling agent is 10 to 30 nm.

[0023] As a specific embodiment of the present invention, R1 and R2 are each independently selected from a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms.

[0024] Preferably, R1 and R2 are each independently selected from methyl or ethyl.

[0025] As a specific embodiment of the present invention, R3 is selected from hydrogen or an alkylene group having 1 to 3 carbon atoms, and R4, R5, and R6 are each independently selected from hydrogen or an alkyl group having 1 to 5 carbon atoms.

[0026] Preferably, R4, R5, and R6 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms.

[0027] Preferably, R3, R4, R5, and R6 are each independently selected from hydrogen, methyl, or ethyl.

[0028] As a specific embodiment of the present invention, R7, R8, and R9 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms.

[0029] Preferably, R7, R8, and R9 are each independently selected from hydrogen or methyl.

[0030] In a second aspect, the present invention provides a method for preparing the compound provided in the first aspect of the present invention, comprising the following steps: mixing a monomer and water to obtain a monomer mixed solution, wherein the monomer includes monomer A, monomer B, monomer C, and monomer D, adjusting the pH of the monomer mixed solution, adding an initiator to the monomer mixed solution, reacting, and drying to obtain the compound.

[0031] As a specific embodiment of the present invention, the initiator is selected from at least one of a redox initiator or an azo initiator.

[0032] Preferably, the initiator is a redox initiator.

[0033] As a specific embodiment of the present invention, based on the total mass of monomer A, monomer B, monomer C, and monomer D being 100 parts by weight, the amount of the redox initiator used is 0.006 to 0.5 part by weight;

[0034] Preferably, it is 0.05 to 0.25 part by weight;

[0035] As a specific embodiment of the present invention, based on the total mass of monomer A, monomer B, monomer C, and monomer D being 100 parts by weight, the amount of the azo initiator used is 0.002 to 0.2 part by weight;

[0036] Preferably, it is 0.01 to 0.1 part by weight.

[0037] As a specific embodiment of the present invention, the redox initiator is an oxidation initiator and / or a reduction initiator;

[0038] The oxidation initiator is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate and hydrogen peroxide; preferably at least one of ammonium persulfate and potassium persulfate.

[0039] As a specific embodiment of the present invention, the organic reducing agent is selected from at least one of N,N-dimethylethanolamine, N,N-dimethylpropanolamine, N,N-dimethylpiperazine, N,N'-dimethylpiperazine, tetramethylurea, N,N-dimethylurea, N,N,N',N'-tetramethylethylenediamine, N,N'-dimethylethylenediamine, N,N'-dimethyl-1,3-propanediamine, 3-methylaminopropylamine and N,N-dimethylethylenediamine;

[0040] Preferably at least one of N,N'-dimethyl-1,3-propanediamine and N,N,N',N'-tetramethylethylenediamine;

[0041] More preferably N,N,N',N'-tetramethylethylenediamine.

[0042] As a specific embodiment of the present invention, the inorganic reducing agent is selected from at least one of sodium bisulfite, sodium sulfite, ferrous sulfate, sodium thiosulfate and urea; preferably sodium bisulfite and / or sodium sulfite.

[0043] As a specific embodiment of the present invention, the azo initiator is selected from at least one of azobisisobutyronitrile, azobis(imidazolinylpropane)dihydrochloride, 4,4'-azobis(4-cyanovaleric acid) and 2,2'-azobis(isobutylamidine)dihydrochloride;

[0044] Preferably at least one of 2,2'-azobis(isobutylamidine)dihydrochloride and azobis(imidazolinylpropane)dihydrochloride.

[0045] As a specific embodiment of the present invention, the pH value of the monomer mixed solution is adjusted to 4-12; preferably 5-10; more preferably 6-9; for example 6, 6.5, 7, 7.5, 8, 8.5, 9.

[0046] Specifically, at least one of sodium hydroxide solution, potassium hydroxide solution and sodium carbonate solution can be used to adjust the pH value of the monomer mixed solution; preferably sodium hydroxide and / or potassium hydroxide.

[0047] As a specific embodiment of the present invention, the concentration of the monomer in the monomer mixed solution is 20 wt% - 30 wt%;

[0048] As a specific embodiment of the present invention, the reaction conditions include: the temperature is 5 to 80 °C; preferably 7 to 70 °C; more preferably 20 to 65 °C.

[0049] As a specific embodiment of the present invention, the reaction conditions include: the time is 1 to 15 hours; preferably 2 to 10 hours; more preferably 3 to 8 hours.

[0050] As a specific embodiment of the present invention, the reaction is carried out under inert conditions.

[0051] As a specific embodiment of the present invention, the reaction is carried out under nitrogen protection.

[0052] As a specific embodiment of the present invention, the drying conditions include: the temperature is 65 to 95 °C, preferably 70 to 90 °C; the drying time is 0.5 to 4.5 hours, preferably 1 to 2.5 hours.

[0053] In a third aspect, the present invention provides a filtration reducer, comprising the compound provided in the first aspect of the present invention or the compound prepared by the preparation method of the compound provided in the second aspect of the present invention.

[0054] In a fourth aspect, the present invention provides an aqueous drilling fluid, containing the compound provided in the first aspect of the present invention or the compound prepared by the preparation method provided in the second aspect of the present invention or the filtration reducer provided in the third aspect of the present invention.

[0055] As a specific embodiment of the present invention, the content of the compound provided in the first aspect of the present invention in the aqueous drilling fluid is 1 wt% to 3 wt%.

[0056] As a specific embodiment of the present invention, the content of the compound prepared by the preparation method of the compound provided in the second aspect of the present invention in the aqueous drilling fluid is 1 wt% to 3 wt%.

[0057] Preferably, the aqueous drilling fluid includes a drilling fluid base slurry.

[0058] In the research, the inventors of the present invention found that a compound composed of specific structural units derived from monomer A, structural units derived from monomer B, structural units derived from monomer C, and structural units derived from monomer D can achieve good anti-temperature and anti-salt / calcium effects when used as a fluid loss reducer for solid-free drilling fluids. This may be attributed to the fact that the structural units derived from monomer A are nanomaterials that can provide plugging for the nano-pores in the filter cake formed by the drilling fluid on the wellbore wall; the structural units derived from monomer B are the main structure of the polymer, which can provide good thickening effect for the polymer; the structural units with the structural units derived from monomer C have sulfonic acid groups that can provide good temperature and salt resistance performance; the structural units derived from monomer D have weak hydrophobic effects and can further enhance the excellent anti-temperature stability performance of the polymer. Under the synergistic effect of the structural units derived from monomer A, the structural units derived from monomer B, the structural units derived from monomer C, and the structural units derived from monomer D, the fluid loss reducer provided by the present invention can be applicable to high-temperature environments to reduce the fluid loss amount and provide a thin and dense filter cake. Moreover, the fluid loss reducer of the present invention has excellent salt and calcium resistance capabilities and meets the use requirements under complex formation conditions.

[0059] The fluid loss reducer provided by the present invention has excellent fluid loss reduction effect. The fluid loss reducer provided by the present invention has excellent anti-temperature performance. When the fluid loss reducer is added to fresh water base mud, the fluid loss amount after aging at 220 °C is 12 - 17 mL; the fluid loss reducer provided by the present invention has good salt and calcium resistance performance. When the fluid loss reducer is added to salt water base mud, the fluid loss amount after high-temperature aging at 180 °C is 25 - 28 mL; when the fluid loss reducer is added to calcium water base mud, the fluid loss amount after high-temperature aging at 180 °C is 21 - 25 mL. Therefore, the fluid loss reducer provided by the present invention has great application potential in high-temperature and high-salt / high-calcium formations. Detailed implementation manners

[0060] The present invention will be further described below in conjunction with specific embodiments, but it does not constitute any limitation to the present invention.

[0061] The raw materials used in the embodiments of the present invention are commercially available. Among them,

[0062] Silane coupling agent modified silica, Jiangsu Xianfeng Nano Materials Technology Co., Ltd., treated with KH570, particle size 20 nm, purity 99 wt%;

[0063] N,N-dimethylacrylamide, Shanghai Aladdin Biochemical Technology Co., Ltd., (containing stabilizer MEHQ)>99.0% (GC);

[0064] 2-acrylamido-2-methylpropanesulfonic acid, Shanghai Aladdin Biochemical Technology Co., Ltd., 98%;

[0065] N-Vinylpyrrolidone, Shanghai Aladdin Biochemical Technology Co., Ltd., 99%, containing 100 ppm NaOH stabilizer;

[0066] Sodium hydroxide, Shanghai Aladdin Biochemical Technology Co., Ltd., ≥98%, pellets (anhydrous);

[0067] Sodium bisulfite, Shanghai Aladdin Biochemical Technology Co., Ltd., AR;

[0068] Ammonium persulfate, Shanghai Aladdin Biochemical Technology Co., Ltd., AR, ≥98%;

[0069] Calcium chloride, Sinopharm Chemical Reagent Co., Ltd., AR, ≥96%.

[0070] In the examples of the present invention, the filtration loss reduction effect of the prepared filtration loss reducer was tested according to the following method:

[0071] (1) Preparation of base slurry

[0072] Take 400 mL of deionized water and add it to a stirring cup. Add 1 g of anhydrous sodium carbonate and 16 g of bentonite to it to prepare a fresh water base slurry containing 4 wt% bentonite.

[0073] Take 400 mL of the prepared fresh water base slurry and add it to a high-speed stirring cup. Add 100 g of sodium chloride to it to prepare a salt water base slurry containing 25 wt% sodium chloride.

[0074] Take 400 mL of the prepared fresh water base slurry and add it to a high-speed stirring cup. Add 20 g of calcium chloride to it to prepare a calcium water base slurry containing 5 wt% calcium chloride.

[0075] (2) Mud aging method:

[0076] The aging experiment was carried out in a high-temperature roller furnace. Add the prepared mud to an aging tank. After hot rolling at the set temperature for 16 hours, cool it to room temperature, take out the mud, and stir it for 10 min to obtain the aged mud.

[0077] (3) Measurement method of filtration loss volume:

[0078] The filtration loss volume of the mud was tested according to the specifications of the American Petroleum Institute (API) and SY / T5621-93 of China. The filtration loss volume of the mud was measured by a medium-pressure filter. At room temperature, a certain volume of mud passed through a filter paper with a diameter of 9 cm under a pressure of 0.69 MPa, and the filtration volume at a filtration time of 30 min was measured.

[0079] Example 1

[0080] 1. Preparation of filtration loss reducer

[0081] Add 200 kg of silica modified with silane coupling agent with a particle size of 20 nm, 150 kg of N,N-dimethylacrylamide, 10 kg of 2-acrylamido-2-methylpropanesulfonic acid, 1 kg of N-vinylpyrrolidone and 1400 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.15 kg of sodium bisulfite and 0.15 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h at a reaction temperature of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a filtration loss reducer A1 by crushing and screening the solidified product.

[0082] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0083] Add the filtration loss reducer A1 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry to obtain a fresh water mud, and test the filtration loss of the fresh water mud after aging at 220 °C. The results are shown in Table 1.

[0084] Add the filtration loss reducer A1 accounting for 2 wt% of the salt water base slurry into the salt water base slurry to obtain a salt water mud, and measure the filtration loss of the salt water mud after aging at 180 °C. The results are shown in Table 2.

[0085] Add the filtration loss reducer A1 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry to obtain a calcium water mud, and measure the filtration loss of the calcium water mud after aging at 180 °C. The results are shown in Table 3.

[0086] Example 2

[0087] 1. Preparation of filtration loss reducer

[0088] Add 250 kg of silica modified with silane coupling agent with a particle size of 20 nm, 200 kg of N,N-dimethylacrylamide, 30 kg of 2-acrylamido-2-methylpropanesulfonic acid, 10 kg of N-vinylpyrrolidone and 1650 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.2 kg of sodium bisulfite and 0.2 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h at a reaction temperature of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a filtration loss reducer A2 by crushing and screening the solidified product.

[0089] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0090] After adding the fluid loss reducer A2 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry, a fresh water mud was obtained, and the fluid loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0091] After adding the fluid loss reducer A2 accounting for 2 wt% of the salt water base slurry into the salt water base slurry, a salt water mud was obtained, and the fluid loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0092] After adding the fluid loss reducer A2 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry, a calcium water mud was obtained, and the fluid loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0093] Example 3

[0094] 1. Preparation of fluid loss reducer

[0095] 200 kg of silica modified by silane coupling agent with a particle size of 20 nm, 300 kg of N,N-dimethylacrylamide, 40 kg of 2-acrylamido-2-methylpropanesulfonic acid, 20 kg of N-vinylpyrrolidone and 1900 kg of deionized water were added to a batching kettle to obtain a monomer mixed solution. Under stirring, sodium hydroxide was added to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. The monomer mixed solution was pumped into a polymerization kettle, and nitrogen was introduced into the polymerization kettle to remove oxygen for 0.5 h. 0.25 kg of sodium bisulfite and 0.25 kg of ammonium persulfate were sequentially added, and the polymerization reaction was carried out at a reaction temperature of 60 °C for 4 h while standing to obtain a copolymer gel. The copolymer gel was dried under hot air at 70 °C for 2 h to obtain a solidified product. The solidified product was crushed and sieved to obtain the fluid loss reducer A3.

[0096] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0097] After adding the fluid loss reducer A3 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry, a fresh water mud was obtained, and the fluid loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0098] After adding the fluid loss reducer A3 accounting for 2 wt% of the salt water base slurry into the salt water base slurry, a salt water mud was obtained, and the fluid loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0099] After adding the fluid loss reducer A3 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry, a calcium water mud was obtained, and the fluid loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0100] Example 4

[0101] 1. Preparation of fluid loss reducer

[0102] Add 250 kg of silane coupling agent modified silica with a particle size of 20 nm, 400 kg of N,N-dimethylacrylamide, 80 kg of 2-acrylamido-2-methylpropanesulfonic acid, 40 kg of N-vinylpyrrolidone and 2600 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.35 kg of sodium bisulfite and 0.35 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h under the reaction temperature condition of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a fluid loss reducer A4 by crushing and screening the solidified product.

[0103] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0104] Add the fluid loss reducer A4 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry to obtain a fresh water mud, and test the fluid loss of the fresh water mud after aging at 220 °C. The results are shown in Table 1.

[0105] Add the fluid loss reducer A4 accounting for 2 wt% of the salt water base slurry into the salt water base slurry to obtain a salt water mud, and measure the fluid loss of the salt water mud after aging at 180 °C. The results are shown in Table 2.

[0106] Add the fluid loss reducer A4 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry to obtain a calcium water mud, and measure the fluid loss of the calcium water mud after aging at 180 °C. The results are shown in Table 3.

[0107] Example 5

[0108] 1. Preparation of fluid loss reducer

[0109] Add 100 kg of silane coupling agent modified silica with a particle size of 20 nm, 200 kg of N,N-dimethylacrylamide, 15 kg of 2-acrylamido-2-methylpropanesulfonic acid, 15 kg of N-vinylpyrrolidone and 1300 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.15 kg of sodium bisulfite and 0.15 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h under the reaction temperature condition of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a fluid loss reducer A5 by crushing and screening the solidified product.

[0110] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0111] After adding a fluid loss reducer A5 accounting for 2 wt% of the fresh water base mud into the fresh water base mud, a fresh water mud was obtained, and the fluid loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0112] After adding a fluid loss reducer A5 accounting for 2 wt% of the salt water base mud into the salt water base mud, a salt water mud was obtained, and the fluid loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0113] After adding a fluid loss reducer A5 accounting for 2 wt% of the calcium water base mud into the calcium water base mud, a calcium water mud was obtained, and the fluid loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0114] Example 6

[0115] 1. Preparation of the fluid loss reducer

[0116] 200 kg of silica modified by silane coupling agent with a particle size of 20 nm, 250 kg of N,N-dimethylacrylamide, 50 kg of 2-acrylamido-2-methylpropanesulfonic acid, 6 kg of N-vinylpyrrolidone and 1900 kg of deionized water were added into a batching kettle to obtain a monomer mixed solution. Under stirring, sodium hydroxide was added to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. The monomer mixed solution was pumped into a polymerization kettle, and nitrogen was introduced into the polymerization kettle for deoxidation for 0.5 h. 0.3 kg of sodium bisulfite and 0.3 kg of ammonium persulfate were sequentially added. Under the condition of a reaction temperature of 60 °C, the static polymerization reaction was carried out for 4 h to obtain a copolymer gel. The copolymer gel was dried under hot air at 70 °C for 2 h to obtain a solidified product. The solidified product was crushed and screened to obtain a fluid loss reducer A6.

[0117] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0118] After adding a fluid loss reducer A6 accounting for 2 wt% of the fresh water base mud into the fresh water base mud, a fresh water mud was obtained, and the fluid loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0119] After adding a fluid loss reducer A6 accounting for 2 wt% of the salt water base mud into the salt water base mud, a salt water mud was obtained, and the fluid loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0120] After adding a fluid loss reducer A6 accounting for 2 wt% of the calcium water base mud into the calcium water base mud, a calcium water mud was obtained, and the fluid loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0121] Example 7

[0122] 1. Preparation of the fluid loss reducer

[0123] Add 200 kg of silane coupling agent modified silica with a particle size of 20 nm, 180 kg of N,N-dimethylacrylamide, 100 kg of 2-acrylamido-2-methylpropanesulfonic acid, 80 kg of N-vinylpyrrolidone and 1900 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 9. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle for deoxygenation for 0.5 h, sequentially add 0.25 kg of sodium bisulfite and 0.25 kg of ammonium persulfate, and carry out a static polymerization reaction for 4 h under the reaction temperature condition of 70 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a fluid loss reducer A7 by crushing and screening the solidified product.

[0124] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0125] Add the fluid loss reducer A7 accounting for 2 wt% of the fresh water base mud into the fresh water base mud to obtain a fresh water mud, and test the fluid loss of the fresh water mud after aging at 220 °C. The results are shown in Table 1.

[0126] Add the fluid loss reducer A7 accounting for 2 wt% of the salt water base mud into the salt water base mud to obtain a salt water mud, and measure the fluid loss of the salt water mud after aging at 180 °C. The results are shown in Table 2.

[0127] Add the fluid loss reducer A7 accounting for 2 wt% of the calcium water base mud into the calcium water base mud to obtain a calcium water mud, and measure the fluid loss of the calcium water mud after aging at 180 °C. The results are shown in Table 3.

[0128] Example 8

[0129] 1. Preparation of fluid loss reducer

[0130] Add 400 kg of silane coupling agent modified silica with a particle size of 20 nm, 220 kg of N,N-dimethylacrylamide, 70 kg of 2-acrylamido-2-methylpropanesulfonic acid, 90 kg of N-vinylpyrrolidone and 2600 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide to the monomer mixed solution to adjust the pH of the monomer mixed solution to 9. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle for deoxygenation for 0.5 h, sequentially add 0.35 kg of sodium bisulfite and 0.35 kg of ammonium persulfate, and carry out a static polymerization reaction for 4 h under the reaction temperature condition of 50 °C to obtain a copolymer gel. Dry the copolymer gel under hot air conditions at 70 °C for 2 h to obtain a solidified product. Obtain a fluid loss reducer A8 by crushing and screening the solidified product.

[0131] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0132] After adding the filtration reducer A8 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry, a fresh water mud was obtained, and the filtration loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0133] After adding the filtration reducer A8 accounting for 2 wt% of the salt water base slurry into the salt water base slurry, a salt water mud was obtained, and the filtration loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0134] After adding the filtration reducer A8 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry, a calcium water mud was obtained, and the filtration loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0135] Example 9

[0136] 1. Preparation of the filtration reducer

[0137] 300 kg of silica modified by silane coupling agent with a particle size of 20 nm, 150 kg of N,N-dimethylacrylamide, 20 kg of 2-acrylamido-2-methylpropanesulfonic acid, 30 kg of N-vinylpyrrolidone and 1900 kg of deionized water were added into a batching kettle to obtain a monomer mixed solution. Under stirring, sodium hydroxide was added to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. The monomer mixed solution was pumped into a polymerization kettle, and nitrogen was introduced into the polymerization kettle to remove oxygen for 0.5 h. 0.35 kg of sodium bisulfite and 0.35 kg of ammonium persulfate were sequentially added. Under the reaction temperature condition of 70 °C, the static polymerization reaction was carried out for 6 h to obtain a copolymer gel. The copolymer gel was dried under hot air conditions at 65 °C for 2 h to obtain a solidified product. The solidified product was crushed and screened to obtain the filtration reducer A9.

[0138] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0139] After adding the filtration reducer A9 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry, a fresh water mud was obtained, and the filtration loss of the fresh water mud after aging at 220 °C was tested. The results are shown in Table 1.

[0140] After adding the filtration reducer A9 accounting for 2 wt% of the salt water base slurry into the salt water base slurry, a salt water mud was obtained, and the filtration loss of the salt water mud after aging at 180 °C was measured. The results are shown in Table 2.

[0141] After adding the filtration reducer A9 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry, a calcium water mud was obtained, and the filtration loss of the calcium water mud after aging at 180 °C was measured. The results are shown in Table 3.

[0142] Comparative Example 1

[0143] 1. Preparation of the copolymer

[0144] Add 150 kg of N,N-dimethylacrylamide, 10 kg of 2-acrylamido-2-methylpropanesulfonic acid, 1 kg of N-vinylpyrrolidone and 600 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide into the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.15 kg of sodium bisulfite and 0.15 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h under the reaction temperature condition of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air condition at 70 °C for 24 h to obtain a solidified product. Obtain modified silica / N,N-dimethylacrylamide / 2-acrylamido-2-methylpropanesulfonate / N-vinylpyrrolidone terpolymer B1 by crushing and screening the solidified product.

[0145] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0146] Add the filtrate reducer B1 accounting for 2 wt% of the fresh water base slurry into the fresh water base slurry to obtain a fresh water mud, and test the filtrate loss of the fresh water mud after aging at 220 °C. The results are shown in Table 1.

[0147] Add the filtrate reducer B1 accounting for 2 wt% of the salt water base slurry into the salt water base slurry to obtain a salt water mud, and measure the filtrate loss of the salt water mud after aging at 180 °C. The results are shown in Table 2.

[0148] Add the filtrate reducer B1 accounting for 2 wt% of the calcium water base slurry into the calcium water base slurry to obtain a calcium water mud, and measure the filtrate loss of the calcium water mud after aging at 180 °C. The results are shown in Table 3.

[0149] Comparative Example 2

[0150] 1. Preparation of copolymer

[0151] Add 200 kg of silane coupling agent modified silica with a particle size of 20 nm, 150 kg of N,N-dimethylacrylamide, 10 kg of 2-acrylamido-2-methylpropanesulfonic acid and 600 kg of deionized water into a batching kettle to obtain a monomer mixed solution. Under stirring, add sodium hydroxide into the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. Pump the monomer mixed solution into a polymerization kettle, introduce nitrogen into the polymerization kettle to remove oxygen for 0.5 h, sequentially add 0.15 kg of sodium bisulfite and 0.15 kg of ammonium persulfate, and carry out static polymerization reaction for 4 h under the reaction temperature condition of 60 °C to obtain a copolymer gel. Dry the copolymer gel under hot air condition at 70 °C for 24 h to obtain a solidified product, and obtain modified silica / N,N-dimethylacrylamide / 2-acrylamido-2-methylpropanesulfonate / N-vinylpyrrolidone binary copolymer B2 by crushing and screening the solidified product.

[0152] 2. Evaluation of Temperature Resistance, Salt Resistance and Calcium Resistance

[0153] After adding filter loss reducer B2 accounting for 2 wt% of the fresh water base mud into the fresh water base mud, fresh water mud was obtained. The filter loss of the fresh water mud after aging at 220 °C was measured, and the results are shown in Table 1.

[0154] After adding filter loss reducer B2 accounting for 2 wt% of the salt water base mud into the salt water base mud, salt water mud was obtained. The filter loss of the salt water mud after aging at 180 °C was measured, and the results are shown in Table 2.

[0155] After adding filter loss reducer B2 accounting for 2 wt% of the calcium water base mud into the calcium water base mud, calcium water mud was obtained. The filter loss of the calcium water mud after aging at 180 °C was measured, and the results are shown in Table 3.

[0156] Comparative Example 3

[0157] 1. Preparation of Copolymer

[0158] 150 kg of N,N-dimethylacrylamide, 10 kg of 2-acrylamido-2-methylpropanesulfonic acid and 600 kg of deionized water were added to a batching kettle to obtain a monomer mixed solution. Under stirring, sodium hydroxide was added to the monomer mixed solution to adjust the pH of the monomer mixed solution to 7. The monomer mixed solution was pumped into a polymerization kettle, and nitrogen was introduced into the polymerization kettle to remove oxygen for 0.5 h. 0.15 kg of sodium bisulfite and 0.15 kg of ammonium persulfate were sequentially added. Under the reaction temperature condition of 60 °C, the static polymerization reaction was carried out for 4 h to obtain a copolymer gel. The copolymer gel was dried under hot air conditions at 70 °C for 24 h to obtain a solidified product. The solidified product was crushed and screened to obtain a modified silica / N,N-dimethylacrylamide / 2-acrylamido-2-methylpropanesulfonate / N-vinylpyrrolidone binary copolymer B3.

[0159] 2. Evaluation of Temperature Resistance, Salt Resistance and Calcium Resistance

[0160] After adding filter loss reducer B3 accounting for 2 wt% of the fresh water base mud into the fresh water base mud, fresh water mud was obtained. The filter loss of the fresh water mud after aging at 220 °C was measured, and the results are shown in Table 1.

[0161] After adding filter loss reducer B3 accounting for 2 wt% of the salt water base mud into the salt water base mud, salt water mud was obtained. The filter loss of the salt water mud after aging at 180 °C was measured, and the results are shown in Table 2.

[0162] After adding filter loss reducer B3 accounting for 2 wt% of the calcium water base mud into the calcium water base mud, calcium water mud was obtained. The filter loss of the calcium water mud after aging at 180 °C was measured, and the results are shown in Table 3.

[0163] Comparative Example 4

[0164] 1. The polymer fluid loss reducer PAC produced by Yanxing Chemical Co., Ltd. is used as copolymer B4.

[0165] 2. Evaluation of temperature resistance, salt resistance and calcium resistance

[0166] After adding the fluid loss reducer B4 accounting for 2 wt% of the fresh water base mud content to the fresh water base mud, fresh water mud is obtained, and the fluid loss of the fresh water mud after aging at 220 °C is measured. The results are shown in Table 1.

[0167] After adding the fluid loss reducer B4 accounting for 2 wt% of the salt water base mud content to the salt water base mud, salt water mud is obtained, and the fluid loss of the salt water mud after aging at 180 °C is measured. The results are shown in Table 2.

[0168] After adding the fluid loss reducer B4 accounting for 2 wt% of the calcium water base mud content to the calcium water base mud, calcium water mud is obtained, and the fluid loss of the calcium water mud after aging at 180 °C is measured. The results are shown in Table 3.

[0169] Table 1 Test results of fluid loss of fluid loss reducers in fresh water base mud after aging at 220 °C in examples and comparative examples

[0170]

[0171]

[0172] It can be seen from the data in Table 1 that the fluid loss of the fresh water base mud added with the fluid loss reducers A1 - A9 of the present invention after high temperature aging at 220 °C is 12 - 17 mL, which is better than that of the current similar product PAC (Comparative Example 4). This shows that the fluid loss reducer prepared in the present invention has good fluid loss reduction effect and temperature resistance performance, and can effectively improve the fluid loss of water-based drilling fluid in high temperature environment; after adding polymers B1 - B3 in Comparative Examples 1 - 3 to the fresh water base mud, the fluid loss after high temperature aging at 220 °C is 25 - 29 mL, indicating that the presence of structural units derived from monomer A and structural units derived from monomer D can significantly improve the temperature resistance performance of the fluid loss reducer, thereby contributing to a greatly improved fluid loss reduction effect.

[0173] Table 2 Measurement results of fluid loss of fluid loss reducers in salt water base mud after aging at 180 °C in examples and comparative examples

[0174] Sample Filtrate volume (mL) A1 25 A2 26 A3 27 A4 28 A5 28 A6 27 A7 25 A8 25 A9 26 B1 43 B2 52 B3 61 B4 31

[0175] It can be seen from the data in Table 2 that the brine-based slurry to which the fluid loss reducers A1 to A9 of the present invention are added has a fluid loss of 25 to 28 mL after high-temperature aging at 180°C, which is better than the current similar product PAC (Comparative Example 4), indicating that the fluid loss reducer prepared by the present invention has good fluid loss reduction effect, temperature resistance and salt resistance, and can effectively improve the fluid loss of water-based drilling fluid in a high temperature and high salt environment; after the polymers B1 to B3 prepared in Comparative Examples 1-3 are added to the brine-based slurry, the fluid loss after high-temperature aging at 180°C is 43 to 61 mL, indicating that the presence of the structural units derived from monomer A and derived from monomer D can significantly improve the temperature resistance and salt resistance of the fluid loss reducer, thereby contributing to greatly improving the fluid loss reduction effect.

[0176] Table 3 Filtration results of the fluid loss reducers in the examples and comparative examples after aging at 180°C in calcium water-based slurry

[0177] Sample Filtrate volume (mL) A1 21 A2 22 A3 25 A4 24 A5 25 A6 24 A7 21 A8 22 A9 23 B1 37 B2 42 B3 49 B4 29

[0178] It can be seen from the data in Table 3 that the calcium water-based slurry to which the fluid loss reducers A1 to A9 of the present invention are added has a fluid loss of 21 to 25 mL after high-temperature aging at 180°C, which is better than the current similar product PAC (Comparative Example 4), indicating that the fluid loss reducer prepared by the present invention can effectively improve the fluid loss of water-based drilling fluid in a high-temperature, high-calcium environment; the fluid loss of polymers B1 to B3 prepared in Comparative Examples 1-3 after high-temperature aging at 180°C is 37 to 49 mL, indicating that the presence of the structural units derived from monomer A and derived from monomer D can significantly improve the temperature resistance and calcium resistance of the fluid loss reducer.

[0179] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A compound, characterized in that, The compound comprises a structural unit derived from monomer A, a structural unit derived from monomer B, a structural unit derived from monomer C, and a structural unit derived from monomer D; The monomer A is hydrophobic nano-silica; The monomer B is selected from one or more of the monomers shown in Formula I: In Formula I, R1 and R2 are each independently selected from hydrogen or C1-C 10 alkyl; The monomer C is selected from one or more of the monomers shown in Formula II: In formula II, R3, R4, R5, and R6 are each independently selected from hydrogen or C1-C 10 alkyl; The monomer D is selected from one or more of the monomers shown in Formula III: In Formula III, R7, R8, and R9 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to C 10 , a branched-chain alkyl group having 3 to C 10 , or a cycloalkyl group having 3 to C 10 .

2. The compound according to claim 1, wherein The compound, by mass parts, comprises: 1 to 99 parts of monomer A, 0.1 to 98 parts of monomer B, 0.01 to 30 parts of monomer C, and 0.001 to 16 parts of monomer D; Preferably, the compound, by mass parts, comprises: 5 to 50 parts of monomer A, 1 to 60 parts of monomer B, 0.1 to 20 parts of monomer C, 0.01 to 15 parts of monomer D; More preferably, the compound, by mass parts, comprises: 20 to 40 parts by weight of monomer A, 15 to 50 parts by weight of monomer B, 1 to 15 parts by weight of monomer C, 0.1 to 10 parts by weight of monomer D.

3. The compound according to claim 1 or 2, characterized in that, The mass ratio of monomer A to monomer B is 1 to 2.

4. The compound according to any one of claims 1-3, characterized in that The hydrophobic nano-silica is nano-silica modified by a silane coupling agent; preferably, the particle size of the nano-silica modified by the silane coupling agent is 10 to 30 nm; And / or, R1 and R2 are each independently selected from a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms; Preferably, R1 and R2 are each independently selected from methyl or ethyl; And / or, R3 is selected from hydrogen or an alkylene group having 1 to 3 carbon atoms, and R4, R5, and R6 are each independently selected from hydrogen or an alkyl group having 1 to 5 carbon atoms; Preferably, R4, R5, and R6 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms; Preferably, R3, R4, R5, and R6 are each independently selected from hydrogen, methyl, or ethyl; And / or, R7, R8, and R9 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 5 carbon atoms, a branched-chain alkyl group having 3 to 5 carbon atoms, or a cycloalkyl group having 3 to 5 carbon atoms; Preferably, R7, R8, and R9 are each independently selected from hydrogen or methyl.

5. A method for preparing the compound according to any one of claims 1-4, characterized in that, Comprises the following steps: mixing the monomers and water to obtain a monomer mixed solution, the monomers including monomer A, monomer B, monomer C, and monomer D; adjusting the pH of the monomer mixed solution, adding an initiator to the monomer mixed solution, reacting, and drying to obtain the compound.

6. The preparation method according to claim 5, characterized in that, The initiator is selected from at least one of redox initiators or azo initiators.

7. The preparation method according to claim 5 or 6, characterized in that, Based on the total mass of monomer A, monomer B, monomer C, and monomer D being 100 parts by weight, the dosage of the redox initiator is 0.006 to 0.5 parts by weight; Preferably 0.05 to 0.25 parts by weight; And / or, based on the total mass of monomer A, monomer B, monomer C, and monomer D being 100 parts by weight, the dosage of the azo initiator is 0.002 to 0.2 parts by weight; Preferably 0.01 to 0.1 parts by weight.

8. The preparation method according to claim 7, characterized in that, The redox initiator is an oxidation initiator and / or a reduction initiator; The oxidation initiator is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide; Preferably, it is at least one of ammonium persulfate and potassium persulfate; And / or, the reduction initiator includes an inorganic reducing agent and an organic reducing agent; Preferably, the organic reducing agent is selected from at least one of N,N-dimethylethanolamine, N,N-dimethylpropanolamine, N,N-dimethylpiperazine, N,N'-dimethylpiperazine, tetramethylurea, N,N-dimethylurea, N,N,N',N'-tetramethylethylenediamine, N,N'-dimethylethylenediamine, N,N'-dimethyl-1,3-propanediamine, 3-methylaminopropylamine, and N,N-dimethylethylenediamine; More preferably, it is at least one of N,N'-dimethyl-1,3-propanediamine and N,N,N',N'-tetramethylethylenediamine; Even more preferably, it is N,N,N',N'-tetramethylethylenediamine; Preferably, the inorganic reducing agent is selected from at least one of sodium bisulfite, sodium sulfite, ferrous sulfate, sodium thiosulfate, and urea; More preferably, it is sodium bisulfite and / or sodium sulfite; And / or, the azo initiator is selected from at least one of azobisisobutyronitrile, azobisimidazolinylpropane dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobisisobutylamidine hydrochloride; Preferably, it is at least one of 2,2'-azobisisobutylamidine hydrochloride and azobisimidazolinylpropane dihydrochloride.

9. The method for preparing the compound according to claim 8, characterized in that, Adjust the pH value of the monomer mixed solution to 4 - 12; preferably 5 - 10; more preferably 6 - 9; And / or, the concentration of the monomer in the monomer mixed solution is 20 wt% - 30 wt%; And / or, the reaction conditions include: the temperature is 5 - 80 °C; preferably 7 - 70 °C; more preferably 20 - 65 °C; And / or, the reaction conditions include: the reaction is carried out under inert conditions, and the time is 1 - 15 hours; preferably 2 - 10 hours; more preferably 3 - 8 hours; And / or, the drying conditions include: the temperature is 65 - 95 °C, preferably 70 - 90 °C; the drying time is 0.5 - 4.5 hours, preferably 1 - 2.5 hours.

10. A filtration reducer, characterized in that, The filtration reducer includes the compound described in any one of claims 1 - 4 or the compound prepared by the preparation method of the compound described in any one of claims 5 - 9.

11. An aqueous drilling fluid containing the compound described in any one of claims 1 - 4 or the compound prepared by the preparation method of the compound described in any one of claims 5 - 9 or the filtration reducer described in claim 10; Preferably, in the aqueous drilling fluid, the content of the compound described in any one of claims 1 - 4 is 1 wt% - 3 wt% or the content of the compound prepared by the preparation method described in any one of claims 5 - 9 is 1 wt% - 3 wt%; Preferably, the aqueous drilling fluid includes a drilling fluid base slurry.

Images