CN111574973A

CN111574973A - Three-water-retention-based drilling fluid system

Info

Publication number: CN111574973A
Application number: CN202010508663.XA
Authority: CN
Inventors: 陈利; 赵秀平
Original assignee: SHIJIAZHUANG HUALAI DINGSHENG TECHNOLOGY CO LTD
Current assignee: SHIJIAZHUANG HUALAI DINGSHENG TECHNOLOGY CO LTD
Priority date: 2020-06-06
Filing date: 2020-06-06
Publication date: 2020-08-25

Abstract

A three-water-retention-based drilling fluid system comprises the following raw materials: 1000 parts of tap water, 40-50 parts of bentonite, 2-3 parts of sodium carbonate, 0.5-1 part of sodium hydroxide, 23-5 parts of coating agent HLBE-23, 16-8 parts of filtrate reducer HLJ-16, 20 parts of filtrate reducer HLJ-615, 5-7 parts of polyanionic cellulose PAC-LV, 25-10 parts of high-temperature salt-resistant filtrate reducer HLKY-25, 320-25 parts of wall fixing agent HLGB-320, 220-25 parts of liquid lubricant HLR, 320-25 parts of lubrication inhibitor HLRH-20, 20-25 parts of solid lubricant for drilling fluid, 35-10 parts of inhibitor HLY-70, 70-80 parts of KCl, 12-2.5 parts of gel blocking agent HLN-12, 10-15 parts of superfine calcium carbonate powder and weighting agent. The drilling fluid has good inhibition and plugging properties, and is used for drilling mudstone-siltstone inclined well sections and horizontal sections. The problem of easy wall of a well unstability that causes of using water base drilling fluid to creep into the in-process is solved, have the three guarantor functions of protection wall of a well, protection hydrocarbon reservoir, environmental protection.

Description

Three-water-retention-based drilling fluid system

Technical Field

The invention relates to an oil drilling fluid system, in particular to a three-water-retention-base drilling fluid system and a preparation method of the three-water-retention-base drilling fluid system.

Background

As the development of oil fields enters the middle and later stages, a large number of old well bottom water coning causes most of oil wells to be flooded, some storage with large mining difficulty is mined to improve the recovery ratio and the reserve utilization degree, and a slant well or horizontal well drilling mode is adopted to communicate with reservoirs around a shaft in the drilling and production process, so that the drilling difficulty is increased. The Mingzhi group, Dongying group and the Sanchi street group with depression in the wing mainly develop variegated mudstone and fine siltstone, and drilling in the mudstone stratum often causes the well wall instability and complexity, and the mudstone is easy to hydrate and disperse and expand when meeting water, so that the well wall collapse is caused by the reduction of the rock strength. Therefore, the inhibition requirement on the drilling fluid is high, the risk of well wall collapse is increased due to the influences of various factors such as well track, ground stress and the like in the process of deep well, inclined well, horizontal well and drilling, the water loss must be greatly reduced, the plugging is strengthened to reduce the liquid from entering the stratum, the oil-based drilling fluid has incomparable advantages in the aspects of lubrication, anti-blocking and resistance reduction, the dragging and pressure problem during sliding drilling can be avoided, but the oil-based drilling fluid contains a large amount of organic substances, the cost is high, the biotoxicity is high, the cost is high during harmless treatment, and the application scale is small. The conventional drilling fluid system causes the stability of a hydrated well wall of a mudstone layer to be poor when the drilling meets the mudstone; the drill cuttings generated by poor pollution resistance are easy to hydrate, the recovery rate is low, and the workload of maintenance and treatment is large; the lubrication anti-seizing capability is insufficient. Therefore, the development of a novel water-based drilling fluid which can be suitable for a mudstone stratum to replace an oil-based drilling fluid and solve the problems of well wall stability, reservoir pollution and the like is a key technology of mudstone drilling at present and is also a difficult point of mudstone drilling at home and abroad.

The inventors searched the following related patent documents: CN105694829A discloses a low-friction drilling fluid for drilling shale, which comprises the following raw materials in parts by weight: 900 times of tap water and 1000 times of tap water; 30-50 parts of bentonite for drilling fluid; na (Na)₂CO₃1.5-2.5; strong entrapment for drilling fluidPreparation HX-930-40; the high-temperature-resistant, salt-resistant and anti-collapse filtrate reducer KFT-15-10 for the drilling fluid; WNP-210-20, a natural polymer filtrate reducer for drilling fluid; viscosity reducer MFC 1-3 for drilling fluid; 20-40 parts of nano paraffin emulsion for drilling fluid; solid lubricant HRH-20110-20 for drilling fluid; adjusting pH of the system to 9 with 40% alkali solution, adding barite to adjust density to 1.25g/cm³. CN103013470A discloses a strong inhibition drilling fluid system, which comprises the following components by mass percent according to the mass of added water as 100 percent: 2.5 to 4.5 percent of bentonite slurry, 0.1 to 0.3 percent of alkaline regulator, 0.3 to 2.0 percent of shale inhibitor, 0.2 to 0.4 percent of metal ion polymer, 2.0 to 5.0 percent of lignite resin, 2.0 to 5.0 percent of sulfonated phenolic resin, 1.0 to 3.0 percent of cation emulsified asphalt, 0.5 to 3.0 percent of lubricant, 0.2 to 0.8 percent of emulsifier, 2.0 to 8.0 percent of crude oil and 1.0 to 3.0 percent of superfine calcium carbonate. The drilling fluid system has strong capacity of resisting the pollution of inferior soil, salt and calcium; strong inhibition and good plugging effect. CN104046340A discloses a high-temperature-resistant and salt-resistant drilling fluid system which comprises the following components in percentage by mass based on 100% of the mass of added water: 2 to 7 percent of bentonite slurry, 0.1 to 0.3 percent of alkaline regulator, 0.3 to 2 percent of shale inhibitor, 0.5 to 4 percent of high-temperature resistant fluid loss additive A, 0.4 to 5 percent of temperature-resistant and salt-resistant fluid loss additive B and 1 to 7 percent of plugging anti-collapse agent, and has strong capacity of resisting inferior soil and calcium pollution. CN 102424746A discloses a strongly-inhibitory solid-free polyamine-formate drilling fluid system. The shale oil additive contains strongly-inhibiting polyamine shale inhibitor, and usually comprises a fluid loss additive, a polymer coating agent, a tackifier, a lubricant and other necessary treatment agents, the system does not contain a solid phase, and the weighting agent is formate. The drilling fluid additive comprises 0.1-5% of shale inhibitor, 0.1-5% of filtrate reducer, 0.1-5% of coating agent, 0.1-5% of tackifier and 0.1-5% of lubricant, wherein a weighting agent formate is added according to the actual requirement in the drilling process, and the balance is water for preparing the drilling fluid. And a plugging agent, a pH regulator and other conventional drilling fluid treating agents can be added in a drilling site according to the site conditions. The drilling fluid system has strong inhibition effect on water-sensitive shale, and does not contain solid phases such as clay, barite and the likeAnd the damage to the oil-gas layer is greatly reduced. CN102226076A discloses a highly-inhibitive anti-sloughing low-damage drilling fluid, which relates to the technical field of drilling fluids and comprises the following components in percentage by weight: 2 to 5 percent of silicate, 0.5 to 1.0 percent of small cation inhibitor, 0.3 to 0.8 percent of hydrolyzed polyacrylamide, 0.3 to 0.5 percent of viscosity-increasing cutting agent and fluid loss agent: 1-3%, barite 0-6%, formaldehyde 0.05-0.1%, and the balance of water. The invention has the characteristics of long-time collapse resistance, strong inhibition, good plugging effect, low damage to low-porosity low-permeability low-abundance reservoir, simple and easy formula and slurry preparation process.

Some strongly-inhibited water-based drilling fluid systems contain a large number of sulfonic groups, have certain environmental pollution risks, have limited sand carrying capacity, are influenced by environmental protection and performance indexes, and have narrow application range. Can not simultaneously meet the current environmental protection requirement and the use requirement of a slant well or a horizontal well containing mudstone on site.

Disclosure of Invention

The invention aims to solve the technical problem of providing a three-water-retention-based drilling fluid system which is green and environment-friendly, contains no components and elements which have influences on the environment, has shale inhibition, less formation filtration loss, good lubricity and strong sand carrying capacity, is suitable for drilling of an inclined well section or a horizontal section of a soft formation in mudstone-siltstone, can protect an oil-gas layer, solves the problem of easy borehole wall instability in the drilling process of using a water-based drilling fluid, and has three protection functions of protecting a borehole wall, protecting the oil-gas layer and protecting the environment.

Therefore, the invention also provides a preparation method of the three-water-retention-base drilling fluid system.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a three-protection water-based drilling fluid system (or a water-based drilling fluid system with three protection functions, or a strong-inhibition environment-friendly water-based drilling fluid for drilling mudstone-siltstone) has the technical scheme that the drilling fluid system is prepared from the following raw materials in parts by weight (mass ratio and weight ratio): 1000 parts of tap water, 40-50 parts of bentonite, 2-3 parts of sodium carbonate, 0.5-1 part of sodium hydroxide and coating23-5 parts of HLBE-23, 16-8 parts of HLJ-16, 615-20 parts of HLJ-615, 5-7 parts of polyanionic cellulose PAC-LV, 25-10 parts of HLKY-10 parts of high-temperature salt-resistant filtrate reducer, 320-25 parts of HLGB-320-25 parts of wall-fixing agent, 220-25 parts of liquid lubricant HLR-220, 320-25 parts of lubricating inhibitor HLRH-320-25 parts of solid lubricant for drilling fluid, 35-10 parts of inhibitor HLY-80, 70-80 parts of KCl, 12-2.5 parts of gel blocking agent HLN-12, 10-15 parts of superfine calcium carbonate powder and weighting agent namely barite, wherein the dosage of the weighting agent is determined according to the density of slurry (drilling fluid), and the dosage of the weighting agent is required to meet the requirement that the density of the slurry after adjustment reaches 1.20-1.40 g/cm³The requirements of (1).

The preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 40-50 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2-3 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding 23-5 parts of coating agent HLBE-23 in the stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding 16-8 parts of filtrate reducer HLJ-16 in the stirrer, stirring for 5min after adding, adding 20-615 parts of filtrate reducer HLJ-615 in the stirrer, stirring for 5min after adding, adding 5-7 parts of polyanion cellulose PAC-LV in the stirrer, stirring for 5min after adding, adding 25-10 parts of high-temperature salt-resistant filtrate reducer HLKY in the stirrer, stirring for 5min after adding, adding 320-25 parts of wall fixing agent HLGB-320, stirring for 5min after adding, adding 35-10 parts of inhibitor HLY in the stirrer, stirring for 5min after adding, adding 70-80 parts of KCl in the stirrer, and continuing stirring for 30min, then adding 220-25 parts of liquid lubricant HLR-220 into the mixer, stirring for 5min after adding, adding 320-25 parts of lubrication inhibitor HLRH-25 parts into the mixer, stirring for 5min after adding, adding 20-25 parts of solid lubricant for drilling fluid into the mixer, stirring for 5min after adding, adding 12-2.5 parts of gel blocking agent HLN-12 into the mixer, stirring for 5min after adding, adding 10-15 parts of superfine calcium carbonate powder into the mixer, stirring for 5min after adding, preparing 0.5-1 part of sodium hydroxide into 40 mass percent aqueous solution, and adding the aqueous solution into the mixerThen stirring for 5min, finally adding a weighting agent into the mixer, and adjusting the density of the slurry to be 1.20-1.40 g/cm³Thus obtaining the three-water-retention base drilling fluid system.

In the technical scheme, in the preparation of the modified resin polymer of the wall fixing agent HLGB-3, the use amount of the component poly (1, 3-propylidene pyridinium chloride) can be 0 part (namely, the component is not used). The component poly (1, 3-propylene pyridine chloride) can be used in 12 parts.

In the above technical solution, a preferable technical solution may also be that the three-water-retention-based drilling fluid system is prepared from the following raw materials in parts by mass (mass ratio): 1000 parts of tap water, 40 parts of bentonite, 2 parts of sodium carbonate, 0.6 part of sodium hydroxide, 25 parts of coating agent HLBE-25 parts, 18 parts of filtrate reducer HLJ-18 parts, 620 parts of filtrate reducer HLJ-620 parts, 6 parts of polyanionic cellulose PAC-LV, 26 parts of high-temperature salt-resistant filtrate reducer HLKY-26 parts, 325 parts of wall-fixing agent HLGB-325 parts (no component poly 1, 3-propylene pyridine chloride), 220 parts of liquid lubricant HLR-220 parts, 320 parts of lubrication inhibitor HLRH-320 parts, 20 parts of solid lubricant for drilling fluid (RH203-1), 37 parts of inhibitor HLY-37 parts, 70 parts of KCl, 12.5 parts of gel blocking agent HLN-12.5 parts, 13 parts of calcium carbonate powder and weighting agent, wherein the dosage of the weighting agent is ultrafine to adjust the mud density to 1.20g/cm³The standard is. The main component of the inhibitor HLY-3 is triethylene tetramine, the main component of the liquid lubricant HLR-2 is the combination of two raw materials of L-aspartic acid dimethyl ester hydrochloride and L-glutamic acid dimethyl ester hydrochloride, the mass ratio of the L-aspartic acid dimethyl ester hydrochloride to the L-glutamic acid dimethyl ester hydrochloride is 1:0.8, and the technical scheme can ensure that the performance of the liquid lubricant is good at the high temperature of 160 ℃. The preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 40 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, pre-hydrating for 24 hr at normal temperature and normal pressure, adding coating agent HLBE-25 weight portions and filtering loss reducing agent HLJ-18 weight portions and filtering loss reducing agent HLJ-620 weight portions in the stirrer, stirring for 5min and filtering loss reducing agent HLJ-620 weight portions in the stirrer, and pre-hydrating for 24 hr at high speed of 8000r/min under stirring for 5minAdding polyanionic cellulose PAC-LV 6 parts into a stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-26 parts into the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts into the stirrer, stirring for 5min after adding, adding inhibitor HLY-37 parts into the stirrer, stirring for 5min after adding, adding KCl 70 parts into the stirrer, continuing stirring for 30min, then adding liquid lubricant HLR-220 parts into the stirrer, stirring for 5min after adding, adding lubrication inhibitor HLRH-320 parts into the stirrer, stirring for 5min after adding, adding drilling fluid solid lubricant (RH203-1)20 parts into the stirrer, stirring for 5min after adding, adding gel blocking agent HLN-12.5 parts into the stirrer, stirring for 5min after adding, adding superfine calcium carbonate powder 13 parts into the stirrer, stirring for 5min after adding, preparing 0.6 part of sodium hydroxide into 40 mass percent aqueous solution, adding the aqueous solution into a stirrer, stirring for 5min, finally adding a weighting agent into the stirrer, and adjusting the density of the slurry to be 1.20g/cm³Thus obtaining the three-water-retention base drilling fluid system.

In the above technical solution, a preferable technical solution may also be that the three-water-retention-based drilling fluid system is prepared from the following raw materials in parts by mass (mass ratio): 1000 parts of tap water, 45 parts of bentonite, 2.5 parts of sodium carbonate, 0.7 part of sodium hydroxide, 24 parts of coating agent HLBE-24 parts, HLJ-17 parts of filtrate reducer, HLJ-618 parts of filtrate reducer, polyanionic cellulose PAC-LV7 parts, HLKY-29 parts of high-temperature salt-resistant filtrate reducer, HLGB-325 parts of wall-fixing agent (non-component poly-1, 3-propylidene pyridinium chloride), 222 parts of liquid lubricant HLR-222 parts, 322 parts of lubrication inhibitor HLRH-322 parts, 22 parts of solid lubricant for drilling fluid (RH203-1), 38 parts of inhibitor HLY-38 parts, 75 parts of KCl, 12.2 parts of gel blocking agent HLN-12.2 parts, 12 parts of superfine calcium carbonate powder and weighting agent, wherein the dosage of the weighting agent is required to meet the adjusted mud density of 1.30g/cm³The requirements of (1). The main component of the inhibitor HLY-3 is tetraethylenepentamine; the main component of the liquid lubricant HLR-2 is L-aspartic acid dimethyl ester hydrochloride. The preparation of the three water-retention based drilling fluid system is described with reference to example 2.

In the above technical solution, a preferable technical solution may be thatThe three-water-retention-base drilling fluid system is prepared from the following raw materials in parts by mass: 1000 parts of tap water, 50 parts of bentonite, 3 parts of sodium carbonate, 0.9 part of sodium hydroxide, 25 parts of coating agent HLBE-25 parts, filtrate reducer HLJ-16 parts, filtrate reducer HLJ-616 parts, polyanionic cellulose PAC-LV7 parts, high-temperature salt-resistant filtrate reducer HLKY-210 parts, wall-fixing agent HLGB-325 parts (no component poly-1, 3-propylene pyridine chloride), liquid lubricant HLR-225 parts, lubrication inhibitor HLRH-325 parts, solid lubricant for drilling fluid (RH203-1)25 parts, inhibitor HLY-310 parts, KCl 75 parts, gel blocking agent HLN-12.5 parts, calcium carbonate powder 13 parts and weighting agent, wherein the dosage of the weighting agent is ultra-fine and is required to meet the condition that the density of the adjusted slurry reaches 1.40g/cm³The requirements of (1). The main component of the inhibitor HLY-3 is diethylenetriamine; the main component of the liquid lubricant HLR-2 is L-glutamic acid dimethyl ester hydrochloride. The preparation of the three water-retention based drilling fluid system is described with reference to example 3.

The bentonite, sodium carbonate (soda), sodium hydroxide (caustic soda), superfine calcium carbonate powder and barite used for the drilling fluid in the preparation method are all products sold in the market; the coating agent HLBE-2, the filtrate reducer HLJ-1, the filtrate reducer HLJ-6, the PAC-LV, the high-temperature salt-resistant filtrate reducer HLKY-2, the wall fixing agent HLGB-3, the liquid lubricant HLR-2, the lubrication inhibitor HLRH-3, the solid lubricant RH203(RH203-1) for the drilling fluid, the inhibitor HLY-3, the KCl and the gel plugging agent HLN-1 can be purchased from Shijiazhuang Hualeiding Shenzhong technology Limited company (address: 0311 + 85293520 in Shijiazhuang Xin City clean chemical park, Hebei province). The qualified person can use the product only after the product is checked according to the industry standard or the enterprise standard. Table 1 is a detailed table of the basic raw materials of the three water-retention based drilling fluid system, specifically see table 1.

TABLE 1 three water-retention base drilling fluid system base material list

Wherein: the particle size of the superfine calcium carbonate powder is 5-10 μm, and the particle size of the barite is 50-80 μm.

The coating agent HLBE-2 mainly comprises a multipolymer, and the multipolymer (or the multipolymer A) is prepared from the following raw materials in parts by mass: 110 parts of clear water, 0.6 part of cane sugar, namely brown sugar, 17 parts of acrylamide, 5 parts of N, N-dimethylacrylamide, 0.4 part of 4-vinyl guaiacol, 12 parts of allyl trimethyl ammonium chloride, 1.5 parts of chelating agent, 0.1 part of initiator, 12 parts of shale inhibitor, namely poly-hydroxypropyl dimethyl ammonium chloride and 25 parts of tackifier; the initiator is a combination of two raw materials of potassium permanganate and potassium vanadate, and the mass ratio of the potassium permanganate to the potassium vanadate is 1: 2; the chelating agent is a combination of EDTA and lactic acid, and the mass ratio of EDTA to lactic acid is 2: 1; the tackifier is a combination of xanthan gum, hydroxypropyl guar HPG and hydroxypropyl sesbania HPTQ, and the mass ratio of the xanthan gum to the hydroxypropyl guar HPG to the hydroxypropyl sesbania HPTQ is 2:1: 1; the preparation method of the multipolymer comprises the following process steps: preparation of polymer powder: adding 110 parts of clear water into a reaction kettle, starting stirring, sequentially adding sucrose, acrylamide, N-dimethylacrylamide, 4-vinyl guaiacol, allyl trimethyl ammonium chloride, a chelating agent and poly hydroxypropyl dimethyl ammonium chloride according to the mass ratio, slowly heating to 55 ℃, adding an initiator for aqueous solution polymerization, performing polymerization reaction for 4.5 hours at the reaction temperature of 55 ℃ to obtain a gel-like object, and finally drying and crushing the gel-like object to obtain polymer powder, wherein the drying temperature is 45 ℃; preparing a coating agent multipolymer: and (3) mixing the polymer powder obtained in the step (I) and the tackifier by using a powder mixer to obtain the product, namely the multipolymer.

The main component of the fluid loss additive HLJ-1 is acrylamide/acrylic acid copolymer, and the acrylamide/acrylic acid copolymer (or copolymer B) is prepared from the following raw materials in parts by weight: 100 parts of clean water, 20 parts of starch, 2.5 parts of 3-chloro-2-hydroxypropanesulfonic acid sodium salt, 25 parts of acrylamide, 10 parts of acrylic acid, 1.5 parts of initiator, 15 parts of nitro potassium humate, 12 parts of pseudo-boehmite and 25 parts of additive; the starch is corn flour; the additive is a combination of carboxymethyl cellulose and polyanionic cellulose PAC-LV, and the weight ratio of carboxymethyl cellulose to polyanionic cellulose PAC-LV is 1: 2; the initiator is the combination of two raw materials of potassium permanganate and potassium vanadate, and the weight ratio of the potassium permanganate to the potassium vanadate is 1: 1.5; the preparation method of the acrylamide/acrylic acid copolymer comprises the following process steps: preparation of a copolymer solution: adding clear water into a reaction kettle according to the weight ratio, adding starch into the clear water, slowly heating the temperature in the reaction kettle to 75 ℃, starting stirring, gelatinizing for 30min, then cooling the product to 40 ℃, adding a NaOH solution with the mass percentage concentration of 20% into the reaction kettle to adjust the pH value to 10, then adding 3-chloro-2-hydroxy sodium propanesulfonate into the reaction kettle, slowly heating the temperature in the reaction kettle to 55 ℃ for reaction for 9h, and then sequentially adding acrylamide, acrylic acid and an initiator into the reaction kettle for copolymerization reaction for 3h at the temperature of 65 ℃ to obtain a copolymer glue solution; preparing copolymer powder: putting the copolymer glue solution obtained in the step I into an oven, drying at the temperature of 55 ℃ to obtain a copolymer solid, and crushing to obtain copolymer powder; preparing a filtrate reducer: adding the copolymer powder obtained in the step two, the potassium nitrohumate, the pseudo-boehmite and the additive into a mixer, and uniformly mixing and stirring to obtain the product, namely the acrylamide/acrylic acid copolymer.

The main component of the filtrate reducer HLJ-6 is natural modified alkyl glucoside, and the natural modified alkyl glucoside is alpha-methyl glucoside.

The high-temperature salt-resistant fluid loss additive HLKY-2 mainly comprises modified gum resin, wherein the modified gum resin (or the component C) is prepared from the following raw materials in parts by weight: 220 parts of clear water, 35 parts of sodium methallylsulfonate, 10 parts of N, N-dimethylacrylamide, 0.7 part of temperature-resistant monomer namely 4-vinyl guaiacol, 25 parts of methacryloyloxyethyl trimethyl ammonium chloride, 5 parts of chelating agent namely sodium citrate, 0.5 part of initiator, 35 parts of gum resin, 10 parts of 40% sodium hydroxide solution, 10 parts of propylene oxide and 20 parts of additive namely polyvinyl alcohol powder; in the initiator, the mass ratio of the azo initiator to the redox initiator is 3: 2, the azo initiator is azodiisobutyronitrile, the redox initiator is potassium persulfate, the reducing agent is sodium bisulfite, and the mass ratio of the oxidizing agent to the reducing agent is 2: 1; the preparation method of the modified gum resin comprises the following process steps: aqueous solution polymerization: adding 100 parts of clear water into a reaction kettle, starting stirring, sequentially adding sodium methallylsulfonate, N-dimethylacrylamide, a temperature-resistant monomer, methacryloxyethyl trimethyl ammonium chloride and a chelating agent according to the mass ratio, slowly heating to 60 ℃, adding an initiator to perform aqueous solution polymerization, performing polymerization for 5 hours at the reaction temperature of 60 ℃ to obtain a gel-like object, and finally drying and crushing the gel to obtain polymer powder, wherein the drying temperature is 50 ℃; preparing modified resin: adding 120 parts of clear water into a reaction kettle, adding gum resin according to the mass ratio under the condition of starting stirring, slowly heating to 60 ℃, stirring and dissolving for 1h, then cooling to 45 ℃, gradually adding 10 parts of NaOH aqueous solution with the mass percentage concentration of 40%, alkalifying, adding epoxypropane according to the mass ratio after alkalizing for 1h, reacting for 20h at 45 ℃ to obtain viscous liquid, and finally drying and crushing the solution to obtain modified gum resin powder, wherein the drying temperature is 50 ℃; preparing a high-temperature salt-resistant filtrate reducer: and (3) mixing the polymer powder obtained in the step (I), the modified gum resin powder obtained in the step (II) and the additive by using a powder mixer to obtain a product, namely the modified gum resin.

The main component of the polyanionic cellulose PAC-LV is polyanionic cellulose (namely polyanionic cellulose D), and the preparation method of the polyanionic cellulose (namely polyanionic cellulose D) comprises the following steps: putting 100 parts of refined cotton linter into a kneader, adding 115 parts of NaOH aqueous solution and 120 parts of ethanol solution with the mass percentage concentration of 20% under the cooling condition for alkalization, wherein the alkalization reaction temperature is 25 ℃, and reacting for 2.5h to obtain alkalized cellulose, etherifying the alkalized cellulose and 65 parts of chloroacetic acid/isopropanol solution, the content of chloroacetic acid in the chloroacetic acid/isopropanol solution is 80.0% w/w, the etherification temperature is 70 ℃, reacting for 3h, cooling to room temperature after etherification reaction, neutralizing by using hydrochloric acid with the volume concentration of 10%, removing by-products by using the ethanol solution, distilling to remove ethanol and isopropanol, drying and crushing to obtain polyanionic cellulose (namely polyanionic cellulose D); the parts are parts by mass.

The main component of the wall-fixing agent HLGB-3 is a modified resin polymer, and the modified resin polymer (or the component E) is prepared from the following raw materials in parts by mass: 200 parts of clean water, 20 parts of starch, 9 parts of a sodium hydroxide aqueous solution with the mass percentage concentration of 40%, 7 parts of 2-chloroethyl trimethyl ammonium chloride, 25 parts of acrylamide, 15 parts of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of an initiator, 10 parts of potassium nitrohumate, 15 parts of pseudo-boehmite, 0-12 parts of poly-1, 3-propylidene pyridinium chloride and 25 parts of an auxiliary agent; the starch is corn flour; the auxiliary agent is MgO and Al₂O₃Combination of two raw materials, MgO and Al₂O₃The mass ratio of (A) to (B) is 2: 1; the initiator is the combination of two raw materials of potassium permanganate and potassium vanadate, and the mass ratio of the potassium permanganate to the potassium vanadate is 1.5: 1; the granularity of the pseudo-boehmite is 120 meshes; the number average molecular weight of the poly-1, 3-propylidene pyridinium chloride is 12000, and the structural formula of the poly-1, 3-propylidene pyridinium chloride is as follows:

the preparation method of the modified resin polymer comprises the following process steps: preparation of copolymer gel: adding 100 parts of clear water into a reaction kettle according to the mass ratio, adding starch into the clear water, slowly heating the temperature in the reaction kettle to 80 ℃, starting stirring, gelatinizing for 30min, cooling the product to 45 ℃, gradually adding the sodium hydroxide aqueous solution into the reaction kettle for alkalization, adding 2-chloroethyl trimethyl ammonium chloride after alkalization is carried out for 1h, slowly heating the temperature in the reaction kettle to 55 ℃ for reaction for 5h, adding the rest clear water into the reaction kettle, stirring uniformly, and then sequentially adding acrylamide, methacryloyloxyethyl trimethyl ammonium chloride and an initiator into the reaction kettle for copolymerization reaction for 3h at 55 ℃ to obtain copolymer gel; preparing copolymer powder: putting the copolymer gel obtained in the step I into an oven, drying at 52 ℃ to obtain a copolymer solid, and crushing to obtain copolymer powder; preparing a wall-strengthening agent: adding the copolymer powder obtained in the second step, the potassium nitrohumate, the pseudo-boehmite, the poly-1, 3-propylidene pyridinium chloride (when the content of the poly-1, 3-propylidene pyridinium chloride is 0, the component is not contained), and the auxiliary agent into a mixer, and uniformly mixing and stirring to obtain a final product, namely the modified resin polymer.

In the technical scheme, in the preparation of the modified resin polymer of the wall fixing agent HLGB-3, the use amount of the component poly (1, 3-propylidene pyridinium chloride) can be 0 part (namely, the component is not used). At this time, the modified resin polymer is prepared from the following raw materials in parts by mass: 200 parts of clean water, 20 parts of starch, 9 parts of sodium hydroxide aqueous solution with the mass percentage concentration of 40%, 7 parts of 2-chloroethyl trimethyl ammonium chloride, 25 parts of acrylamide, 15 parts of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of initiator, 10 parts of potassium nitrohumate, 15 parts of pseudo-boehmite and 25 parts of auxiliary agent. The first step and the second step are the same as the above. Step three, preparing a wall strengthening agent: adding the copolymer powder obtained in the step two, the potassium nitrohumate, the pseudo-boehmite and the auxiliary agent into a mixer, and uniformly mixing and stirring to obtain a final product, namely the modified resin polymer.

In the technical scheme, in the preparation of the modified resin polymer of the wall fixing agent HLGB-3, the using amount of the component poly (1, 3-propylidene pyridinium chloride) can be 12 parts (see example 4). Poly-1, 3-propylidene pyridinium chloride is a commercial product, and its provenance can be found in drilling fluid process principle compiled by Huanghanren, published in 2016 (8 months), chapter seven, chemical and treating agents for drilling fluid materials, page 285.

The main component of the inhibitor HLY-3 is micromolecule organic amine, the micromolecule organic amine is one or the combination of more than two of ethylenediamine, diethylenetriamine, triethylene tetramine and tetraethylenepentamine, and the proportion is arbitrary when the micromolecule organic amine is combined. The main component of the liquid lubricant HLR-2 is bionic amino acid ester, the bionic amino acid ester is one or the combination of L-aspartic acid dimethyl ester hydrochloride or L-glutamic acid dimethyl ester hydrochloride, the proportion is arbitrary when the bionic amino acid ester is combined, and the bionic amino acid ester can adopt the L-aspartic acid dimethyl ester hydrochloride.

The main component of the lubricating inhibitor HLRH-3 is a nano ester-based hydrate, and the preparation method of the nano ester-based hydrate (or the component F) comprises the following process steps: sequentially adding 20 parts of methyl potassium silicate, 25 parts of methyl oleate, 15 parts of deionized water, 10 parts of No. 5 white oil, 20 parts of No. 7 white oil, 6.8 parts of polyoxyethylene sorbitan monooleate and 3.4 parts of sorbitan monooleate into a reaction kettle, and fully mixing and dissolving the raw materials to obtain a mixture; secondly, emulsifying the mixture at 70 ℃ for 2h to obtain an intermediate product; thirdly, cooling the intermediate product obtained in the second step, adding 10 parts of nano silicon dioxide powder at 40 ℃ to fully and uniformly mix the mixture, cooling the mixture to room temperature, and discharging the mixture to obtain the nano ester-based hydrate; the parts are parts by mass.

The main component of the gel blocking agent HLN-1 is bionic nano polymer gel, and the preparation method of the bionic nano polymer gel (or the component G and the gel G) comprises the following process steps: preparing an alkyl solution: adding 30 parts of distilled water into a stirring cup, slowly adding 2 parts of 2-acrylamide-2-methylpropanesulfonic acid and 20 parts of lactic acid in the stirring process, uniformly stirring, adding an aqueous solution of 0.4 part of sodium hydroxide and 11 parts of distilled water, adjusting the pH value to be 7-8 by using a sodium hydroxide standard solution, uniformly stirring to obtain an alkyl solution, putting the alkyl solution into a maintenance bottle for maintenance, and preparing a titanium-based solution: adding 1.4 parts of nano titanium dioxide into a beaker, wetting the beaker by 14 parts of distilled water, and slowly adding 9 parts of a cross-linking agent until the nano titanium dioxide is completely dispersed to prepare a titanium-based solution, wherein the particle size of the nano titanium dioxide is 40-50 nm, the cross-linking agent is polyethylene glycol, and PEG-1000 is selected; preparing a bionic nano plugging agent: adding 1.4 parts of isooctyl 3-mercaptopropionate serving as a molecular weight regulator into the titanium-based solution, supplementing 5 parts of distilled water, uniformly stirring, adding the mixture into the alkyl solution in a maintenance bottle, heating to 55 ℃, and uniformly stirring; dissolving 0.4 part of potassium persulfate in 5 parts of distilled water, adding the obtained potassium persulfate solution into a maintenance bottle, heating to 55 ℃, fully reacting for 4.5 hours, adjusting the pH value of the solution to 7-9 by using a potassium hydroxide solution, and cooling to room temperature to obtain a product, namely the bionic nano polymer gel; the parts are parts by mass.

The solid lubricant (RH203-1) for the drilling fluid is prepared from the following raw materials in parts by weight: 35 parts of polyethylene glycol 400, 1 part of boric acid, 1 part of catalyst, 10 parts of white oil, 5 parts of surfactant, 1 part of defoaming agent, 25 parts of mica powder and 30 parts of talcum powder; the white oil is a combination of three raw materials of No. 7 white oil, No. 10 white oil and No. 15 white oil, and the weight ratio of the three raw materials of No. 7 white oil, No. 10 white oil and No. 15 white oil is 1: 1.5; the surfactant is a combination of two raw materials of a Tween T-80 surfactant and an AEO-9 surfactant, and the weight ratio of the Tween T-80 surfactant to the AEO-9 surfactant is 1: 1.5; the catalyst is ferric chloride; the defoaming agent is polydimethylsiloxane; the preparation method of the solid lubricant for the drilling fluid comprises the following process steps: synthesizing boric acid polyethylene glycol ester: adding 35 parts of polyethylene glycol 400 into a reaction kettle according to the weight ratio, adding 1 part of boric acid and 1 part of catalyst into the polyethylene glycol 400, slowly heating to 130 ℃, starting stirring, reducing pressure, refluxing and completely dividing water, reacting for 3 hours, and completely cooling the reaction liquid to room temperature; preparing a solid lubricant: adding 2.5 parts of No. 7 white oil, 3.75 parts of No. 10 white oil, 3.75 parts of No. 15 white oil, 2 parts of Tween T-80 surfactant, 3 parts of AEO-9 surfactant and 1 part of defoamer into the reaction solution, then mixing and stirring uniformly, finally adding 25 parts of mica powder and 30 parts of talcum powder, and fully stirring to obtain the product, namely the solid lubricant for the drilling fluid.

The invention provides a three-water-retention-based drilling fluid system and a preparation method thereof. The three water-retention based drilling fluid systems of the present invention have good performance, see tables 2-5, which follow in this specification. The performance of the invention is as follows: the normal-temperature medium-pressure water loss is less than or equal to 5mL and the high-temperature high-pressure water loss is less than or equal to 13mL after normal-temperature or high-temperature aging, and the water loss reducing effect is good. The shale expansion reduction rate is over 75 percent, the rock debris rolling recovery rate is over 95.2 percent, and the lubrication coefficient reduction rate is more than or equal to 92 percent.

The three-water-retention-based drilling fluid system disclosed by the invention is green and environment-friendly, does not contain components and elements which influence the environment, has shale inhibition, less formation filtration loss, good lubricity and strong sand carrying capacity, is suitable for drilling of an inclined shaft section or a horizontal section of a soft formation in mudstone-siltstone, and solves the problem of borehole wall instability easily caused in the drilling process of using the water-based drilling fluid.

Compared with the technical scheme of the drilling fluid with low friction resistance for drilling shale disclosed by CN105694829A, the drilling fluid with low friction resistance has obviously different components, is more resistant to high temperature (above 150 ℃) and has better environmental protection property.

In conclusion, the shale-sandstone drilling fluid has good performance at the high temperature of 150 ℃, has good shale inhibition effect in a mudstone-siltstone layer, can keep good mud performance in the whole well section, can protect an oil-gas layer, is green and environment-friendly, has good biodegradability, and meets the technical requirement of mudstone-siltstone drilling in the market. The invention has three protection functions of protecting well wall, protecting oil-gas layer and protecting environment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Examples 1-4 are three water-retaining based drilling fluid systems according to the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In examples 1 to 3, the modified resin polymer of the wall fixing agent HLGB-3 was prepared in an amount of 0 part (i.e., no component) of the component poly 1, 3-propylidene pyridinium chloride. In example 4, the component poly (1, 3-propylidene pyridinium chloride) was used in an amount of 12 parts.

Example 1: the three-water-retention-base drilling fluid system is characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water and bentonite40 parts, 2 parts of sodium carbonate, 0.6 part of sodium hydroxide, 25 parts of coating agent HLBE-25 parts, 18 parts of filtrate reducer HLJ-18 parts, 620 parts of filtrate reducer HLJ-620 parts, 6 parts of polyanionic cellulose PAC-LV, 26 parts of high-temperature salt-resistant filtrate reducer HLKY-26 parts, 325 parts of wall-fixing agent HLGB-325 parts (no component poly 1, 3-propylene pyridine chloride is used in preparation), 220 parts of liquid lubricant HLR-220 parts, 320 parts of lubrication inhibitor HLRH-320 parts, 20 parts of solid lubricant (RH203-1) for drilling fluid, 37 parts of inhibitor HLY-37 parts, 70 parts of KCl, 12.5 parts of gel blocking agent HLN-12.5 parts, 13 parts of lubricating inhibitor HLRH-320 parts, and weighting agent, wherein the dosage of the weighting agent is required to meet the condition that the density of the adjusted slurry reaches 1.20g/cm³The requirements of (1). The main component of the inhibitor HLY-3 is triethylene tetramine, the main component of the liquid lubricant HLR-2 is a combination of two raw materials of L-aspartic acid dimethyl ester hydrochloride and L-glutamic acid dimethyl ester hydrochloride, and the mass ratio of the L-aspartic acid dimethyl ester hydrochloride to the L-glutamic acid dimethyl ester hydrochloride is 1: 0.8. The preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 40 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding coating agent HLBE-25 parts in a stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding filtrate reducer HLJ-18 parts in the stirrer, stirring for 5min after adding, adding filtrate reducer HLJ-620 parts in the stirrer, stirring for 5min after adding, adding polyanionic cellulose PAC-LV 6 parts in the stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-26 parts in the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts in the stirrer, stirring for 5min after adding, adding inhibitor HLY-37 parts in the stirrer, stirring for 5min after adding, adding KCl 70 parts in the stirrer, continuing stirring for 30min, then adding liquid lubricant-220 parts in the stirrer, stirring for 5min after adding, adding lubricating inhibitor HLRH-320 parts into a stirrer, stirring for 5min after adding, adding 20 parts of solid lubricant (RH203-1) for drilling fluid into the stirrer, stirring for 5min after adding, adding gel blocking agent HLN-12.5 parts into the stirrer, stirring for 5min after adding, stirring for 5min after stirringAdding 13 parts of superfine calcium carbonate powder into a mixer, stirring for 5min after adding, preparing 0.6 part of sodium hydroxide into a water solution with the mass percent concentration of 40%, adding the water solution into a stirrer, stirring for 5min, finally adding a weighting agent into the stirrer, and adjusting the slurry density to be 1.20g/cm³Thus obtaining the three-water-retention base drilling fluid system.

Example 2: the three-water-retention-base drilling fluid system is prepared from the following raw materials in parts by mass: 1000 parts of tap water, 45 parts of bentonite, 2.5 parts of sodium carbonate, 0.7 part of sodium hydroxide, 24 parts of coating agent HLBE-24 parts, HLJ-17 parts of filtrate reducer, HLJ-618 parts of filtrate reducer, polyanionic cellulose PAC-LV7 parts, HLKY-29 parts of high-temperature salt-resistant filtrate reducer, HLGB-325 parts of wall-fixing agent (no component poly-1, 3-propylene pyridine chloride is used in preparation), 222 parts of liquid lubricant HLR-222 parts, 322 parts of lubrication inhibitor HLRH-322 parts, 22 parts of solid lubricant for drilling fluid (RH203-1), 38 parts of inhibitor HLY-38 parts, 75 parts of KCl, 12.2 parts of gel blocking agent HLN-12.2 parts, 12 parts of superfine calcium carbonate powder and weighting agent, wherein the dosage of the weighting agent is required to meet the adjusted mud density of 1.30g/cm³The requirements of (1); the main component of the inhibitor HLY-3 is tetraethylenepentamine; the main component of the liquid lubricant HLR-2 is L-aspartic acid dimethyl ester hydrochloride. The preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 45 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2.5 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding coating agent HLBE-24 parts in the stirrer under electric stirring at high speed of 8000r/min, stirring for 5min after adding, adding filtrate reducer HLJ-17 parts in the stirrer, stirring for 5min after adding, adding filtrate reducer HLJ-618 parts in the stirrer, stirring for 5min after adding, adding polyanionic cellulose PAC-LV7 parts in the stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-29 parts in the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts in the stirrer, stirring for 5min after adding, adding inhibitor HLY-38 parts in the stirrer, stirring for 5min after adding, adding KCl 75 parts in the stirrer, and continuing stirring for 30min, then adding liquid lubricant HLR-222 parts into the mixer, stirring for 5min after adding, adding lubrication inhibitor HLRH-322 parts into the mixer, stirring for 5min after adding, adding 22 parts of solid lubricant (RH203-1) for drilling fluid into the mixer, stirring for 5min after adding, adding gel blocking agent HLN-12.2 parts into the mixer, stirring for 5min after adding, adding 12 parts of superfine calcium carbonate powder into the mixer, stirring for 5min after adding, preparing 0.7 part of sodium hydroxide into a solution with the mass percentage concentration of 40%, adding the solution into the mixer, stirring for 5min, adding weighting agent into the mixer finally, and adjusting the mud density to be 1.30g/cm³Thus obtaining the three-water-retention base drilling fluid system.

Example 3: the three-water-retention-base drilling fluid system is prepared from the following raw materials in parts by mass: 1000 parts of tap water, 50 parts of bentonite, 3 parts of sodium carbonate, 0.9 part of sodium hydroxide, 25 parts of coating agent HLBE-25 parts, filtrate reducer HLJ-16 parts, filtrate reducer HLJ-616 parts, polyanionic cellulose PAC-LV7 parts, high-temperature salt-resistant filtrate reducer HLKY-210 parts, wall-fixing agent HLGB-325 parts (no component poly 1, 3-propylene pyridine chloride is used in preparation), liquid lubricant HLR-225 parts, lubrication inhibitor HLRH-325 parts, solid lubricant for drilling fluid (RH203-1)25 parts, inhibitor HLY-310 parts, KCl 75 parts, gel blocking agent HLN-12.5 parts, superfine calcium carbonate powder 13 parts and weighting agent, wherein the dosage of the weighting agent is required to meet the condition that the density of the adjusted slurry reaches 1.40g/cm³The requirements of (1). The main component of the inhibitor HLY-3 is diethylenetriamine; the main component of the liquid lubricant HLR-2 is L-glutamic acid dimethyl ester hydrochloride. The preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 50 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, and after stirring for 20min, 3 parts of Na is added into the stirrer₂CO₃Stirring for 30min, pre-hydrating for 24 hr at normal temperature and normal pressure, adding coating agent HLBE-25 weight portions and filtering loss reducing agent HLJ-16 weight portions in the stirrer while stirring at high speed of 8000r/min for 5min, adding filtering loss reducing agent HLJ-616 weight portions and filtering loss reducing agent HLJ-616 weight portions in the stirrer, stirring for 5min, and adding polyanion in the stirrerCellulose PAC-LV7 parts, stirring for 5min after adding, adding HLKY-210 parts of high-temperature salt-resistant fluid loss additive into a stirrer, stirring for 5min after adding, adding HLGB-325 parts of wall fixing agent into the stirrer, stirring for 5min after adding, adding HLY-310 parts of inhibitor into the stirrer, stirring for 5min after adding, adding KCl 75 parts into the stirrer, continuing stirring for 30min, then adding HLR-225 parts of liquid lubricant into the stirrer, stirring for 5min after adding, adding HLRH-325 parts of lubrication inhibitor into the stirrer, stirring for 5min after adding, adding 25 parts of solid lubricant (203-1) for drilling fluid into the stirrer, stirring for 5min after adding, adding HLN-12.5 parts of gel blocking agent into the stirrer, stirring for 5min after adding, adding 13 parts of superfine calcium carbonate powder into the stirrer, stirring for 5min after adding, 0.9 part of sodium hydroxide is prepared into 40 percent aqueous solution by mass percent and is added into a stirrer to be stirred for 5min, and finally weighting agent is added into the stirrer to adjust the mud density to 1.40g/cm³Thus obtaining the three-water-retention base drilling fluid system.

Example 4: the three-water-retention-base drilling fluid system is prepared from the following raw materials in parts by mass: 1000 parts of tap water, 48 parts of bentonite, 3 parts of sodium carbonate, 0.8 part of sodium hydroxide, 24 parts of coating agent HLBE-24 parts, HLJ-17 parts of filtrate reducer, HLJ-618 parts of filtrate reducer, polyanionic cellulose PAC-LV7 parts, HLKY-28 parts of high-temperature salt-resistant filtrate reducer, HLGB-324 parts of wall fixing agent, HLR-223 parts of liquid lubricant, HLRH-322 parts of lubrication inhibitor, 22 parts of solid lubricant (RH203-1) for drilling fluid, HLY-38 parts of inhibitor, KCl 75 parts, HLN-12.5 parts of gel blocking agent, 14 parts of superfine calcium carbonate powder and weighting agent namely barite, wherein the dosage of the weighting agent is required to meet the requirement that the density of the adjusted slurry reaches 1.40g/cm³The requirements of (1). The main component of the inhibitor HLY-3 is triethylene tetramine, the main component of the liquid lubricant HLR-2 is a combination of two raw materials of L-aspartic acid dimethyl ester hydrochloride and L-glutamic acid dimethyl ester hydrochloride, and the mass ratio of the L-aspartic acid dimethyl ester hydrochloride to the L-glutamic acid dimethyl ester hydrochloride is 1: 0.8; in the preparation of the modified resin polymer of the wall fixing agent HLGB-3, the usage amount of the component poly (1, 3-propylidene pyridinium chloride) is 12 parts. The three-water-retention base drilling fluidThe preparation method of the system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 48 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, and 3 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding 4 parts of coating agent HLBE-2 into the stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding 7 parts of filtrate reducer HLJ-1 into the stirrer, stirring for 5min after adding, adding 18 parts of filtrate reducer HLJ-6 into the stirrer, stirring for 5min after adding, adding 7 parts of polyanion cellulose PAC-LV into the stirrer, stirring for 5min after adding, adding 8 parts of high-temperature salt-resistant filtrate reducer HLKY-2 into the stirrer, stirring for 5min after adding, adding 24 parts of wall fixing agent HLGB-3 into the stirrer, stirring for 5min after adding, adding 8 parts of inhibitor HLY-3 into the stirrer, stirring for 5min after adding, adding 75 parts of KCl into the stirrer, continuing stirring for 30min, then adding 23 parts of lubricant HLR into the stirrer, stirring for 5min after adding, adding 22 parts of lubricating inhibitor HLRH-3 into a stirrer, stirring for 5min after adding, adding 22 parts of solid lubricant (RH203-1) for drilling fluid into the stirrer, stirring for 5min after adding, adding 2.5 parts of gel blocking agent HLN-1 into the stirrer, stirring for 5min after adding, adding 14 parts of superfine calcium carbonate powder into the stirrer, stirring for 5min after adding, preparing 0.8 part of sodium hydroxide into an aqueous solution with the mass percent concentration of 40%, adding the aqueous solution into the stirrer, stirring for 5min, adding a weighting agent into the stirrer, and adjusting the mud density to be 1.40g/cm³Thus obtaining the three-water-retention base drilling fluid system.

The following is the experimental part of the invention:

pH value: and taking a small amount of prepared drilling fluid, immersing the test paper in the drilling fluid for 0.5s, taking out, and comparing with a color plate to obtain the pH value.

Rheological property of the drilling fluid: and (3) after the prepared drilling fluid sample is placed into a slurry cup to be tested, testing the reading values of phi 600 and phi 300 of the drilling fluid sample according to the regulation of GB/T16783.1. The apparent viscosity, plastic viscosity and dynamic shear force of the drilling fluid were obtained and are shown in table 2.

The plastic viscosity was calculated according to formula (1):

AV＝Φ600-Φ300 (1)

the apparent viscosity was calculated according to equation (2):

YP＝0.48×(Φ300-η_P) (2)

the apparent viscosity was calculated according to equation (3):

in the formula: AV-plastic viscosity, mPas;

YP-dynamic shear force, Pa;

η_a-apparent viscosity, mPa · s;

phi 600-dial reading at 600 r/min;

phi 300-dial reading at 300 r/min.

Drilling fluid filtration performance:

preparing base slurry: 350mL of distilled water is measured and placed in a cup, 22.5g of sodium bentonite for drilling fluid test and 0.75g of anhydrous sodium carbonate are added, high-speed stirring is carried out for 20min, at least two times of stirring are carried out in the process, clay adhered to the wall of the container is scraped off, and the mixture is maintained in a closed container for 24h to serve as base slurry.

Normal temperature low pressure filtration loss:

the drilling fluid prepared according to the embodiments 1-3 is subjected to hot rolling aging for 16h at normal temperature and 150 ℃, and the water loss amount of the drilling fluid is measured by a medium-pressure filtration loss instrument at normal temperature, wherein the pressure difference is 690 +/-35 kPa.

The drilling fluid prepared according to the embodiments 1-3 is subjected to hot rolling aging for 16h at normal temperature and 150 ℃, and then the high-temperature high-pressure filtration loss (150 ℃/3450kPa) is measured according to a method 3.3 in GB/T16783-1997. The results are shown in tables 2 to 5. Example 4 is the experimental result after hot roll aging at 160 ℃ for 16 h.

Linear expansion of drilling fluid: weighing 10.0g of calcium bentonite for drilling fluid, drying for 4 hours at 105 +/-3 ℃, filling into a test cylinder of a shale expansion instrument, adding 2.86MPa pressure on a press machine, and keeping for 5 minutes to obtain a test core. And (3) mounting the measuring cylinder with the rock core on a shale expansion instrument, injecting a drilling fluid sample solution into the measuring cylinder, measuring the linear expansion amount at different times, and simultaneously using distilled water as a blank test. The results are shown in Table 3.

According to equation (4) to calculate

In the formula: b-core linear expansion reduction rate,%;

△H₁-linear core expansion in distilled water, mm;

△H₂the core linear expansion of the drilling fluid, mm;

rock debris rolling recovery rate: taking a depression subsidence area 91 in the wing, cleaning rock debris with the well depth of 3100-3300 m, drying, sieving, and selecting the rock debris with the particle size of 6-10 meshes for later use. Weighing 50g of rock debris, mixing the rock debris with the drilling fluid, aging the mixture for 16h at 150 ℃, screening the mixture through a 40-mesh screen, cleaning the rock debris in the screen, collecting, drying and weighing the rock debris. And simultaneously, performing a clean water and rock debris test. The test results are shown in Table 4.

Lubrication coefficient: and (4) opening the motor according to the operation instruction of the EP-B type lubricating instrument, and pressurizing to 16.95 N.m (the rotating speed is 60r/min) to measure the lubricating coefficient of the sample to be measured. The results are shown in Table 5.

The lubrication coefficient decrease rate was calculated according to equation (5).

In the formula:

eta-reduction of lubrication coefficient,%;

ω₀-the base slurry lubrication factor, dimension, is one;

ω₁-drilling fluid lubrication factor, dimension is one.

TABLE 2 Performance test results for three water-retention based drilling fluid systems (examples 1, 2, 3, 4)

TABLE 3 determination of Linear expansion reduction for three water-retention based drilling fluid systems (examples 1, 2, 3, 4)

TABLE 4 Rolling recovery determination results for three water-retention based drilling fluid systems (examples 1, 2, 3, 4)

Drilling fluid formula	Conditions of the experiment	Recovered mass/g	Percent recovery%
				Clear water and rock debris	Aging at 150 deg.C for 16h	4.52	9.04
Example 1+ rock debris	Aging at 150 deg.C for 16h	47.5	95.20
				Example 2+ rock debris	Aging at 150 deg.C for 16h	48.1	96.20
Example 3+ rock debris	Aging at 150 deg.C for 16h	48.7	97.40
				Example 4+ rock debris	Aging at 160 deg.C for 16h	46.3	95.00

TABLE 5 lubricating property determination results for three water-retention based drilling fluid systems (examples 1, 2, 3, 4)

As can be seen from tables 2 to 5: the three-water-retention-based drilling fluid system prepared by the embodiments of the invention can achieve good performance effect. The normal-temperature medium-pressure water loss is less than or equal to 5mL and the high-temperature high-pressure water loss is less than or equal to 13mL after normal-temperature or high-temperature aging, and the water loss reducing effect is good. The shale expansion reduction rate is over 75 percent, the rock debris rolling recovery rate is over 95.2 percent, and the lubrication coefficient reduction rate is more than or equal to 92 percent.

The invention provides a three-water-retention-base drilling fluid system which is green and environment-friendly, does not contain components and elements which have (adverse) influence on the environment, has good biodegradability, belongs to an environment-friendly product, is nontoxic and harmless, can be slowly degraded under natural conditions, and does not have adverse influence on the environment. Can effectively inhibit shale hydration, improve the wall building function of the drilling fluid, improve the drilling quality and efficiency and is suitable for drilling in mudstone-siltstone inclined well sections and horizontal sections.

In conclusion, the shale-sandstone drilling fluid has good performance at the high temperature of 150 ℃ (example 4 has good performance at the high temperature of 160 ℃), has good shale inhibition effect in a mudstone-siltstone layer, can keep good mud performance in the whole well section, can protect an oil-gas layer, is green and environment-friendly, has good biodegradability, and meets the technical requirements of mudstone-siltstone drilling in the market. The invention has three protection functions of protecting well wall, protecting oil-gas layer and protecting environment.

Claims

1. A three-water-retention-based drilling fluid system is characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water, 40-50 parts of bentonite, 2-3 parts of sodium carbonate, 0.5-1 part of sodium hydroxide, 23-5 parts of coating agent HLBE-23, 16-8 parts of filtrate reducer HLJ-16, 20 parts of filtrate reducer HLJ-615, 5-7 parts of polyanionic cellulose PAC-LV, 25-10 parts of high-temperature salt-resistant filtrate reducer HLKY-25, 320-25 parts of wall fixing agent HLGB-220, 25-220 parts of liquid lubricant HLR-lubricating inhibitor HLRH-320, 20-25 parts of solid lubricant for drilling fluid, 35-10 parts of inhibitor HLY-70, 70-80 parts of KCl, 12-2.5 parts of gel blocking agent HLN-12, 10-15 parts of superfine calcium carbonate powder and weighting agent namely barite, wherein the dosage of the weighting agent is required to meet the adjusted density of the slurry of 1.20-1.40 g/cm³The requirements of (1);

the coating agent HLBE-2 mainly comprises a multipolymer, and the multipolymer is prepared from the following raw materials in parts by mass: 110 parts of clear water, 0.6 part of cane sugar, namely brown sugar, 17 parts of acrylamide, 5 parts of N, N-dimethylacrylamide, 0.4 part of 4-vinyl guaiacol, 12 parts of allyl trimethyl ammonium chloride, 1.5 parts of chelating agent, 0.1 part of initiator, 12 parts of shale inhibitor, namely poly-hydroxypropyl dimethyl ammonium chloride and 25 parts of tackifier; the initiator is a combination of two raw materials of potassium permanganate and potassium vanadate, and the mass ratio of the potassium permanganate to the potassium vanadate is 1: 2; the chelating agent is a combination of EDTA and lactic acid, and the mass ratio of EDTA to lactic acid is 2: 1; the tackifier is a combination of xanthan gum, hydroxypropyl guar HPG and hydroxypropyl sesbania HPTQ, and the mass ratio of the xanthan gum to the hydroxypropyl guar HPG to the hydroxypropyl sesbania HPTQ is 2:1: 1; the preparation method of the multipolymer comprises the following process steps: preparation of polymer powder: adding 110 parts of clear water into a reaction kettle, starting stirring, sequentially adding sucrose, acrylamide, N-dimethylacrylamide, 4-vinyl guaiacol, allyl trimethyl ammonium chloride, a chelating agent and poly hydroxypropyl dimethyl ammonium chloride according to the mass ratio, slowly heating to 55 ℃, adding an initiator for aqueous solution polymerization, performing polymerization reaction for 4.5 hours at the reaction temperature of 55 ℃ to obtain a gel-like object, and finally drying and crushing the gel-like object to obtain polymer powder, wherein the drying temperature is 45 ℃; preparing a coating agent multipolymer: mixing the polymer powder obtained in the step I and the tackifier by a powder mixer to obtain a product, namely the multipolymer;

the main component of the fluid loss additive HLJ-1 is acrylamide/acrylic acid copolymer, and the acrylamide/acrylic acid copolymer is prepared from the following raw materials in parts by weight: 100 parts of clean water, 20 parts of starch, 2.5 parts of 3-chloro-2-hydroxypropanesulfonic acid sodium salt, 25 parts of acrylamide, 10 parts of acrylic acid, 1.5 parts of initiator, 15 parts of nitro potassium humate, 12 parts of pseudo-boehmite and 25 parts of additive; the starch is corn flour; the additive is a combination of carboxymethyl cellulose and polyanionic cellulose PAC-LV, and the weight ratio of carboxymethyl cellulose to polyanionic cellulose PAC-LV is 1: 2; the initiator is the combination of two raw materials of potassium permanganate and potassium vanadate, and the weight ratio of the potassium permanganate to the potassium vanadate is 1: 1.5; the preparation method of the acrylamide/acrylic acid copolymer comprises the following process steps: preparation of a copolymer solution: adding clear water into a reaction kettle according to the weight ratio, adding starch into the clear water, slowly heating the temperature in the reaction kettle to 75 ℃, starting stirring, gelatinizing for 30min, then cooling the product to 40 ℃, adding a NaOH solution with the mass percentage concentration of 20% into the reaction kettle to adjust the pH value to 10, then adding 3-chloro-2-hydroxy sodium propanesulfonate into the reaction kettle, slowly heating the temperature in the reaction kettle to 55 ℃ for reaction for 9h, and then sequentially adding acrylamide, acrylic acid and an initiator into the reaction kettle for copolymerization reaction for 3h at the temperature of 65 ℃ to obtain a copolymer glue solution; preparing copolymer powder: putting the copolymer glue solution obtained in the step I into an oven, drying at the temperature of 55 ℃ to obtain a copolymer solid, and crushing to obtain copolymer powder; preparing a filtrate reducer: adding the copolymer powder obtained in the step two, the potassium nitrohumate, the pseudo-boehmite and the additive into a mixer, and uniformly mixing and stirring to obtain a product, namely the acrylamide/acrylic acid copolymer;

the main component of the filtrate reducer HLJ-6 is natural modified alkyl glucoside, and the natural modified alkyl glucoside is alpha-methyl glucoside;

the high-temperature salt-resistant fluid loss additive HLKY-2 mainly comprises modified gum resin, wherein the modified gum resin is prepared from the following raw materials in parts by weight: 220 parts of clear water, 35 parts of sodium methallylsulfonate, 10 parts of N, N-dimethylacrylamide, 0.7 part of temperature-resistant monomer namely 4-vinyl guaiacol, 25 parts of methacryloyloxyethyl trimethyl ammonium chloride, 5 parts of chelating agent namely sodium citrate, 0.5 part of initiator, 35 parts of gum resin, 10 parts of 40% sodium hydroxide solution, 10 parts of propylene oxide and 20 parts of additive namely polyvinyl alcohol powder; in the initiator, the mass ratio of the azo initiator to the redox initiator is 3: 2, the azo initiator is azodiisobutyronitrile, the redox initiator is potassium persulfate, the reducing agent is sodium bisulfite, and the mass ratio of the oxidizing agent to the reducing agent is 2: 1; the preparation method of the modified gum resin comprises the following process steps: aqueous solution polymerization: adding 100 parts of clear water into a reaction kettle, starting stirring, sequentially adding sodium methallylsulfonate, N-dimethylacrylamide, a temperature-resistant monomer, methacryloxyethyl trimethyl ammonium chloride and a chelating agent according to the mass ratio, slowly heating to 60 ℃, adding an initiator to perform aqueous solution polymerization, performing polymerization for 5 hours at the reaction temperature of 60 ℃ to obtain a gel-like object, and finally drying and crushing the gel to obtain polymer powder, wherein the drying temperature is 50 ℃; preparing modified resin: adding 120 parts of clear water into a reaction kettle, adding gum resin according to the mass ratio under the condition of starting stirring, slowly heating to 60 ℃, stirring and dissolving for 1h, then cooling to 45 ℃, gradually adding 10 parts of NaOH aqueous solution with the mass percentage concentration of 40%, alkalifying, adding epoxypropane according to the mass ratio after alkalizing for 1h, reacting for 20h at 45 ℃ to obtain viscous liquid, and finally drying and crushing the solution to obtain modified gum resin powder, wherein the drying temperature is 50 ℃; preparing a high-temperature salt-resistant filtrate reducer: mixing the polymer powder obtained in the step I, the modified gum resin powder obtained in the step II and the additive by adopting a powder mixer to obtain a product, namely the modified gum resin;

the main component of the wall-fixing agent HLGB-3 is a modified resin polymer, and the modified resin polymer is prepared from the following raw materials in parts by mass: 200 parts of clean water, 20 parts of starch, 9 parts of a sodium hydroxide aqueous solution with the mass percentage concentration of 40%, 7 parts of 2-chloroethyl trimethyl ammonium chloride, 25 parts of acrylamide, 15 parts of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of an initiator, 10 parts of potassium nitrohumate, 15 parts of pseudo-boehmite, 0-12 parts of poly-1, 3-propylidene pyridinium chloride and 25 parts of an auxiliary agent; the starch is corn flour; the auxiliary agent is MgO and Al₂O₃Combination of two raw materials, MgO and Al₂O₃The mass ratio of (A) to (B) is 2: 1; the initiator is the combination of two raw materials of potassium permanganate and potassium vanadate, and the mass ratio of the potassium permanganate to the potassium vanadate is 1.5: 1; the granularity of the pseudo-boehmite is 120 meshes; the number average molecular weight of the poly-1, 3-propylidene pyridinium chloride is 12000, and the structural formula of the poly-1, 3-propylidene pyridinium chloride is as follows:

the preparation method of the modified resin polymer comprises the following process steps: preparation of copolymer gel: adding 100 parts of clear water into a reaction kettle according to the mass ratio, adding starch into the clear water, slowly heating the temperature in the reaction kettle to 80 ℃, starting stirring, gelatinizing for 30min, cooling the product to 45 ℃, gradually adding the sodium hydroxide aqueous solution into the reaction kettle for alkalization, adding 2-chloroethyl trimethyl ammonium chloride after alkalization is carried out for 1h, slowly heating the temperature in the reaction kettle to 55 ℃ for reaction for 5h, adding the rest clear water into the reaction kettle, stirring uniformly, and then sequentially adding acrylamide, methacryloyloxyethyl trimethyl ammonium chloride and an initiator into the reaction kettle for copolymerization reaction for 3h at 55 ℃ to obtain copolymer gel; preparing copolymer powder: putting the copolymer gel obtained in the step I into an oven, drying at 52 ℃ to obtain a copolymer solid, and crushing to obtain copolymer powder; preparing a wall-strengthening agent: adding the copolymer powder obtained in the second step, the potassium nitrohumate, the pseudo-boehmite, the poly-1, 3-propylidene pyridinium chloride and the auxiliary agent into a mixer, and uniformly mixing and stirring to obtain a product, namely the modified resin polymer;

the main component of the liquid lubricant HLR-2 is bionic amino acid ester which is one or the combination of two of L-aspartic acid dimethyl ester hydrochloride or L-glutamic acid dimethyl ester hydrochloride, and the proportion is arbitrary when the bionic amino acid ester is combined; the main component of the inhibitor HLY-3 is micromolecule organic amine, the micromolecule organic amine is one or the combination of more than two of ethylenediamine, diethylenetriamine, triethylene tetramine and tetraethylenepentamine, and the proportion is arbitrary when the micromolecule organic amine is combined;

the main component of the lubricating inhibitor HLRH-3 is a nano ester-based hydrate, and the preparation method of the nano ester-based hydrate comprises the following process steps: sequentially adding 20 parts of methyl potassium silicate, 25 parts of methyl oleate, 15 parts of deionized water, 10 parts of No. 5 white oil, 20 parts of No. 7 white oil, 6.8 parts of polyoxyethylene sorbitan monooleate and 3.4 parts of sorbitan monooleate into a reaction kettle, and fully mixing and dissolving the raw materials to obtain a mixture; secondly, emulsifying the mixture at 70 ℃ for 2h to obtain an intermediate product; thirdly, cooling the intermediate product obtained in the second step, adding 10 parts of nano silicon dioxide powder at 40 ℃ to fully and uniformly mix the mixture, cooling the mixture to room temperature, and discharging the mixture to obtain the nano ester-based hydrate; the parts are parts by mass;

the main component of the gel blocking agent HLN-1 is bionic nano polymer gel, and the preparation method of the bionic nano polymer gel comprises the following process steps: preparing an alkyl solution: adding 30 parts of distilled water into a stirring cup, slowly adding 2 parts of 2-acrylamide-2-methylpropanesulfonic acid and 20 parts of lactic acid in the stirring process, uniformly stirring, adding an aqueous solution of 0.4 part of sodium hydroxide and 11 parts of distilled water, adjusting the pH value to be 7-8 by using a sodium hydroxide standard solution, uniformly stirring to obtain an alkyl solution, putting the alkyl solution into a maintenance bottle for maintenance, and preparing a titanium-based solution: adding 1.4 parts of nano titanium dioxide into a beaker, wetting the beaker by 14 parts of distilled water, and slowly adding 9 parts of a cross-linking agent until the nano titanium dioxide is completely dispersed to prepare a titanium-based solution, wherein the particle size of the nano titanium dioxide is 40-50 nm, the cross-linking agent is polyethylene glycol, and PEG-1000 is selected; preparing a bionic nano plugging agent: adding 1.4 parts of isooctyl 3-mercaptopropionate serving as a molecular weight regulator into the titanium-based solution, supplementing 5 parts of distilled water, uniformly stirring, adding the mixture into the alkyl solution in a maintenance bottle, heating to 55 ℃, and uniformly stirring; dissolving 0.4 part of potassium persulfate in 5 parts of distilled water, adding the obtained potassium persulfate solution into a maintenance bottle, heating to 55 ℃, fully reacting for 4.5 hours, adjusting the pH value of the solution to 7-9 by using a potassium hydroxide solution, and cooling to room temperature to obtain a product, namely the bionic nano polymer gel; the parts are parts by mass;

the preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 40-50 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2-3 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding 23-5 parts of coating agent HLBE-23 in the stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding 16-8 parts of filtrate reducer HLJ-16 in the stirrer, stirring for 5min after adding, adding 20-615 parts of filtrate reducer HLJ-615 in the stirrer, stirring for 5min after adding, adding 5-7 parts of polyanion cellulose PAC-LV in the stirrer, stirring for 5min after adding, adding 25-10 parts of high-temperature salt-resistant filtrate reducer HLKY in the stirrer, stirring for 5min after adding, adding 320-25 parts of wall fixing agent HLGB-320, stirring for 5min after adding, adding 35-10 parts of inhibitor HLY in the stirrer, stirring for 5min after adding, adding 70-80 parts of KCl in the stirrer, and continuing stirring for 30min, then adding 220-25 parts of liquid lubricant HLR-220 into the mixer, stirring for 5min after adding, adding 320-25 parts of lubrication inhibitor HLRH-320 into the mixer, stirring for 5min after adding, adding 20-25 parts of solid lubricant for drilling fluid into the mixer, stirring for 5min after adding, adding liquid lubricant into the mixer, stirring for 5min after addingAdding 12-2.5 parts of gel plugging agent HLN-12, stirring for 5min after adding, adding 10-15 parts of superfine calcium carbonate powder into a stirrer, stirring for 5min after adding, preparing 0.5-1 part of sodium hydroxide into 40% aqueous solution with mass percent concentration, adding the aqueous solution into the stirrer, stirring for 5min, finally adding weighting agent into the stirrer, and adjusting the slurry density to 1.20-1.40 g/cm³Thus obtaining the three-water-retention base drilling fluid system.

2. The three-water-retention-base drilling fluid system according to claim 1, wherein the modified resin polymer of the wall-fixing agent HLGB-3 is prepared by using 0 part of poly (1, 3-propylidene pyridinium chloride) as a component.

3. The three-water-retention-base drilling fluid system according to claim 1, wherein the modified resin polymer of the wall-fixing agent HLGB-3 is prepared by using 12 parts of poly (1, 3-propylidene pyridinium chloride) as a component.

4. The three-water-retention-base drilling fluid system according to claim 2, characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water, 40 parts of bentonite, 2 parts of sodium carbonate, 0.6 part of sodium hydroxide, 25 parts of coating agent HLBE-25 parts, 18 parts of filtrate reducer HLJ-18 parts, 620 parts of filtrate reducer HLJ-620 parts, 6 parts of polyanionic cellulose PAC-LV, 26 parts of high-temperature salt-resistant filtrate reducer HLKY-26 parts, 325 parts of wall fixing agent HLGB-325 parts, 220 parts of liquid lubricant HLR-220 parts, 320 parts of lubricating inhibitor HLRH-320 parts, 20 parts of solid lubricant for drilling fluid, 37 parts of inhibitor HLY-37 parts, 70 parts of KCl, 12.5 parts of gel blocking agent HLN-12.5 parts, 13 parts of superfine calcium carbonate powder and weighting agent, wherein the dosage of the weighting agent is required to meet the condition that the density of the adjusted slurry reaches 1.20g/cm³The requirements of (1); the main component of the inhibitor HLY-3 is triethylene tetramine, the main component of the liquid lubricant HLR-2 is a combination of two raw materials of L-aspartic acid dimethyl ester hydrochloride and L-glutamic acid dimethyl ester hydrochloride, and the mass ratio of the L-aspartic acid dimethyl ester hydrochloride to the L-glutamic acid dimethyl ester hydrochloride is 1: 0.8;

the preparation method of the three-water-retention-based drilling fluid system comprises the following steps: first measuring1000 parts of tap water is added into a stirrer, 40 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding coating agent HLBE-25 parts in a stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding filtrate reducer HLJ-18 parts in the stirrer, stirring for 5min after adding, adding filtrate reducer HLJ-620 parts in the stirrer, stirring for 5min after adding, adding polyanionic cellulose PAC-LV 6 parts in the stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-26 parts in the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts in the stirrer, stirring for 5min after adding, adding inhibitor HLY-37 parts in the stirrer, stirring for 5min after adding, adding KCl 70 parts in the stirrer, continuing stirring for 30min, then adding liquid lubricant-220 parts in the stirrer, stirring for 5min after adding, adding a lubrication inhibitor HLRH-320 parts into a stirrer, stirring for 5min after adding, adding 20 parts of solid lubricant for drilling fluid into the stirrer, stirring for 5min after adding, adding 12.5 parts of gel blocking agent HLN into the stirrer, stirring for 5min after adding, adding 13 parts of superfine calcium carbonate powder into the stirrer, stirring for 5min after adding, preparing 0.6 part of sodium hydroxide into an aqueous solution with the mass percentage concentration of 40%, adding the aqueous solution into the stirrer, stirring for 5min, adding a weighting agent into the stirrer, and adjusting the mud density to be 1.20g/cm³Thus obtaining the three-water-retention base drilling fluid system.

5. The three-water-retention-base drilling fluid system according to claim 2, characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water, 45 parts of bentonite, 2.5 parts of sodium carbonate, 0.7 part of sodium hydroxide, 24 parts of coating agent HLBE-24 parts, 17 parts of filtrate reducer HLJ-17 parts, 618 parts of filtrate reducer HLJ-618 parts, 7 parts of polyanionic cellulose PAC-LV, 29 parts of high-temperature salt-resistant filtrate reducer HLKY-29 parts, 325 parts of wall fixing agent HLGB-325 parts, 222 parts of liquid lubricant HLR-222 parts, 322 parts of lubrication inhibitor HLRH-322 parts, 22 parts of solid lubricant for drilling fluid, 38 parts of inhibitor HLY-38 parts, 75 parts of KCl, 12.2 parts of gel blocking agent HLN-12.2 parts, and,12 parts of superfine calcium carbonate powder and a weighting agent, wherein the dosage of the weighting agent is required to meet the requirement that the density of the slurry after adjustment reaches 1.30g/cm³The requirements of (1); the main component of the inhibitor HLY-3 is tetraethylenepentamine; the main component of the liquid lubricant HLR-2 is L-aspartic acid dimethyl ester hydrochloride;

the preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 45 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, 2.5 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding coating agent HLBE-24 parts in the stirrer under electric stirring at high speed of 8000r/min, stirring for 5min after adding, adding filtrate reducer HLJ-17 parts in the stirrer, stirring for 5min after adding, adding filtrate reducer HLJ-618 parts in the stirrer, stirring for 5min after adding, adding polyanionic cellulose PAC-LV7 parts in the stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-29 parts in the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts in the stirrer, stirring for 5min after adding, adding inhibitor HLY-38 parts in the stirrer, stirring for 5min after adding, adding KCl 75 parts in the stirrer, continuing stirring for 30min, then adding liquid lubricant-222 parts in the stirrer, stirring for 5min after adding, adding a lubrication inhibitor HLRH-322 parts into a stirrer, stirring for 5min after adding, adding 22 parts of a solid lubricant for drilling fluid into the stirrer, stirring for 5min after adding, adding 12 parts of gel blocking agent HLN-12.2 parts into the stirrer, stirring for 5min after adding, adding 12 parts of superfine calcium carbonate powder into the stirrer, stirring for 5min after adding, preparing 0.7 part of sodium hydroxide into a solution with the mass percentage concentration of 40%, adding the solution into the stirrer, stirring for 5min, adding a weighting agent into the stirrer, and adjusting the mud density to be 1.30g/cm³Thus obtaining the three-water-retention base drilling fluid system.

6. The three-water-retention-base drilling fluid system according to claim 2, characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water, 50 parts of bentonite and sodium carbonate3 parts of sodium hydroxide, 0.9 part of coating agent HLBE-25 parts of filtrate reducer HLJ-16 parts of filtrate reducer HLJ-616 parts of polyanionic cellulose PAC-LV7 parts, high-temperature salt-resistant filtrate reducer HLKY-210 parts, wall-fixing agent HLGB-325 parts, liquid lubricant HLR-225 parts, lubrication inhibitor HLRH-325 parts, solid lubricant for drilling fluid 25 parts, inhibitor HLY-310 parts, KCl 75 parts, gel blocking agent HLN-12.5 parts, superfine calcium carbonate powder 13 parts and weighting agent, wherein the dosage of the weighting agent is required to meet the requirement that the density of the adjusted slurry reaches 1.40g/cm³The requirements of (1);

the main component of the inhibitor HLY-3 is diethylenetriamine; the main component of the liquid lubricant HLR-2 is L-glutamic acid dimethyl ester hydrochloride;

the preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 50 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, and after stirring for 20min, 3 parts of Na is added into the stirrer₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding coating agent HLBE-25 parts in a stirrer under electric stirring at a high speed of 8000r/min, stirring for 5min after adding, adding filtrate reducer HLJ-16 parts in the stirrer, stirring for 5min after adding, adding filtrate reducer HLJ-616 parts in the stirrer, stirring for 5min after adding, adding polyanionic cellulose PAC-LV7 parts in the stirrer, stirring for 5min after adding, adding high-temperature salt-resistant filtrate reducer HLKY-210 parts in the stirrer, stirring for 5min after adding, adding wall fixing agent HLGB-325 parts in the stirrer, stirring for 5min after adding, adding inhibitor HLY-310 parts in the stirrer, stirring for 5min after adding, adding KCl 75 parts in the stirrer, continuing stirring for 30min, then adding liquid lubricant-225 parts in the stirrer, stirring for 5min after adding, adding a lubrication inhibitor HLRH-325 parts into a stirrer, stirring for 5min after adding, adding 25 parts of solid lubricant for drilling fluid into the stirrer, stirring for 5min after adding, adding 12.5 parts of gel blocking agent HLN into the stirrer, stirring for 5min after adding, adding 13 parts of superfine calcium carbonate powder into the stirrer, stirring for 5min after adding, preparing 0.9 part of sodium hydroxide into an aqueous solution with the mass percentage concentration of 40 percent, and adding the aqueous solution into the stirrerThen stirring for 5min, finally adding weighting agent into the mixer, and adjusting the density of the slurry to 1.40g/cm³Thus obtaining the three-water-retention base drilling fluid system.

7. The three-water-retention-base drilling fluid system according to claim 3, characterized by being prepared from the following raw materials in parts by mass: 1000 parts of tap water, 48 parts of bentonite, 3 parts of sodium carbonate, 0.8 part of sodium hydroxide, 24 parts of coating agent HLBE-24 parts, HLJ-17 parts of filtrate reducer, HLJ-618 parts of filtrate reducer, polyanionic cellulose PAC-LV7 parts, HLKY-28 parts of high-temperature salt-resistant filtrate reducer, HLGB-324 parts of wall fixing agent, HLR-223 parts of liquid lubricant, HLRH-322 parts of lubricating inhibitor, 22 parts of solid lubricant for drilling fluid, HLY-38 parts of inhibitor, KCl 75 parts, HLN-12.5 parts of gel blocking agent, 14 parts of superfine calcium carbonate powder and weighting agent namely barite, wherein the dosage of the weighting agent is required to meet the condition that the density of the slurry after adjustment reaches 1.40g/cm³The requirements of (1); the main component of the inhibitor HLY-3 is triethylene tetramine, the main component of the liquid lubricant HLR-2 is a combination of two raw materials of L-aspartic acid dimethyl ester hydrochloride and L-glutamic acid dimethyl ester hydrochloride, and the mass ratio of the L-aspartic acid dimethyl ester hydrochloride to the L-glutamic acid dimethyl ester hydrochloride is 1: 0.8; in the preparation of the modified resin polymer of the wall fixing agent HLGB-3, the using amount of the component poly (1, 3-propylidene pyridine chloride) is 12 parts;

the preparation method of the three-water-retention-based drilling fluid system comprises the following steps: firstly, 1000 parts of tap water is measured and added into a stirrer, 48 parts of bentonite is added into the stirrer under the electric stirring of low speed 500r/min, and 3 parts of Na is added into the stirrer after stirring for 20min₂CO₃Stirring for 30min, prehydrating for 24h at normal temperature and normal pressure, adding 4 parts of coating agent HLBE-2 into the stirrer under electric stirring at high speed of 8000r/min, stirring for 5min after adding, adding 7 parts of filtrate reducer HLJ-1 into the stirrer, stirring for 5min after adding, adding 18 parts of filtrate reducer HLJ-6 into the stirrer, stirring for 5min after adding, adding 7 parts of polyanion cellulose PAC-LV into the stirrer, stirring for 5min after adding, adding 8 parts of high-temperature salt-resistant filtrate reducer HLKY-2 into the stirrer, stirring for 5min after adding, adding 24 parts of wall fixing agent HL-2 into the stirrerGB-3, stirring for 5min after adding, adding 8 parts of inhibitor HLY-3 into the stirrer, stirring for 5min after adding, after 75 parts of KCl is added into the mixer, stirring is continued for 30min, then 23 parts of liquid lubricant HLR-2 is added into the mixer, stirring is carried out for 5min after the addition is finished, adding 22 parts of lubricating inhibitor HLRH-3 into a mixer, stirring for 5min after the addition is finished, adding 22 parts of solid lubricant for drilling fluid into a mixer, stirring for 5min after adding, adding 2.5 parts of gel blocking agent HLN-1 into the mixer, stirring for 5min after adding, adding 14 parts of superfine calcium carbonate powder into a stirrer, stirring for 5min after adding, preparing 0.8 part of sodium hydroxide into a water solution with the mass percent concentration of 40%, adding the water solution into the stirrer, stirring for 5min, finally adding a weighting agent into the stirrer, and adjusting the slurry density to 1.40 g/cm.³Thus obtaining the three-water-retention base drilling fluid system.