Environment-friendly high-temperature-resistant drilling fluid and preparation method thereof

Abstract

This invention discloses an environmentally friendly, high-temperature resistant drilling fluid and its preparation method, relating to the field of petroleum drilling technology. This invention mixes modified chitosan, modified stearin, and various alkyl glycoside derivatives with specific structures in a specific ratio, allowing the components to work synergistically to achieve functions such as viscosity enhancement, reduced filtration loss, strong inhibition, strong plugging, and high lubrication. While ensuring good environmental performance of the drilling fluid, its high-temperature resistance is improved. Experimental data shows that the environmentally friendly, high-temperature resistant drilling fluid EC provided by this invention... 50 With a value >200,000 mg / L and a temperature resistance of up to 185℃, it helps to achieve green, safe and efficient drilling in high-temperature and complex formations, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, and in particular to an environmentally friendly, high-temperature resistant drilling fluid and its preparation method. Background Technology

[0002] With increasingly stringent global environmental protection requirements, it has become increasingly recognized that green development is an inevitable trend in drilling fluid technology. Current drilling fluid technology is moving towards environmental friendliness to meet the needs of environmentally sensitive areas. Simultaneously, as oil and gas exploration and development expands, the requirements for drilling fluid's high-temperature resistance and performance during actual drilling operations are becoming increasingly stringent, especially when drilling through high-temperature and complex formations. While existing oil-based drilling fluids can meet the requirements for safe and efficient drilling in high-temperature and complex formations, environmental issues are becoming increasingly prominent. Significant cost and public pressure exist regarding the environmental treatment of waste drilling fluids and the post-treatment of oil-based drill cuttings, limiting their application.

[0003] Compared to oil-based drilling fluids, water-based drilling fluids contain no harmful chemicals, are completely biodegradable, and do not pollute the environment. Furthermore, their preparation process is simple and they offer high safety. The main components of water-based drilling fluids are bentonite, water, and various chemical treatment agents. These chemical treatment agents significantly impact the high-temperature resistance and environmental performance of water-based drilling fluids. Currently, several environmentally friendly treatment agents have been developed for water-based drilling fluids, but existing water-based drilling fluids still face a contradiction where environmental performance and high-temperature resistance cannot be simultaneously achieved. Summary of the Invention

[0004] In view of this, the present invention provides an environmentally friendly, high-temperature resistant drilling fluid. By adjusting the proportions of various environmentally friendly treatment agents, the resulting drilling fluid possesses both environmental friendliness and high-temperature resistance. Experimental results show that the environmentally friendly, high-temperature resistant drilling fluid EC provided by the present invention... 50 With a value >200,000 mg / L and a temperature resistance of up to 185℃, it helps to achieve green, safe and efficient drilling in high-temperature and complex formations, and has broad application prospects.

[0005] The environmentally friendly high-temperature resistant drilling fluid provided by this invention comprises, per liter: 3-12g of viscosity improver and shear enhancement agent; 10-20g of filtration loss reducer; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 10-30g of plugging agent; and 10-30g of bentonite.

[0006] The thickening and shearing agent has a structure of formula (I); the filtration loss reducing agent has a structure of formula (II); the inhibitor has a structure of formula (III); the wall-strengthening and anti-collapse agent has a structure of formula (IV); and the lubricant has a structure of formula (V).

[0007]

[0008]

[0009] Where a is selected from integers from 7400 to 7600; b, c, d, e, and q are independently selected from integers from 1 to 20; f, h, m, n, s, and t are independently selected from integers from 1 to 10; g is selected from integers from 1200 to 3100; i, j, k, and u are independently selected from integers from 0 to 4; l, o, and r are independently selected from integers from 1 to 3; p is selected from integers from 1 to 30.

[0010] M and N are independently selected from alkali metal elements;

[0011] R1 and R4 are independently selected from C1 to C4. 14 The alkyl group; R2, R3, R5, R6, R7 and R8 are independently selected from C1 to C4 alkyl groups.

[0012] In some specific implementations, each liter of the environmentally friendly high-temperature resistant drilling fluid includes: 3-10g of viscosity-enhancing and shear-lifting agent; 10-15g of filtration-reducing agent; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 15-30g of plugging agent; and 10-30g of bentonite.

[0013] In some specific implementations, the sealing agent is nano-sized calcium carbonate.

[0014] In some specific implementations, the environmentally friendly high-temperature resistant drilling fluid of the present invention further includes a pH adjuster. In some specific implementations, the pH adjuster is at least one selected from NaOH and Na2CO3.

[0015] In some specific implementations, the environmentally friendly high-temperature resistant drilling fluid of the present invention further includes a weighting agent. In some specific implementations, the weighting agent is barite.

[0016] This invention also provides a method for preparing the above-mentioned environmentally friendly high-temperature resistant drilling fluid, comprising:

[0017] a) Mix bentonite and water evenly and let it stand to cure;

[0018] b) Mix the mixed solution obtained in step a) after static curing with the viscosity improver, filtration reducer, plugging agent, wall-stabilizing and anti-collapse agent, lubricant and inhibitor to obtain an environmentally friendly high-temperature resistant drilling fluid.

[0019] In some specific implementations, the specific operation of static curing in step a) is: room temperature curing for 20 to 30 hours.

[0020] In some specific implementations, the method for uniformly mixing bentonite and water in step a) is as follows: stirring at a stirring speed of 8000–13000 r / min for 10–30 min.

[0021] This invention, by mixing modified chitosan, modified stearin, and various alkyl glycoside derivatives with specific structures in a specific ratio, allows the components to work synergistically, achieving functions such as thickening and shear enhancement, reducing filtration loss, strong inhibition, strong plugging, and high lubrication. This improves the high-temperature resistance of the drilling fluid while maintaining its good environmental performance. Experimental data shows that the environmentally friendly, high-temperature resistant drilling fluid EC provided by this invention... 50 With a value >200,000 mg / L and a temperature resistance of up to 185℃, it helps to achieve green, safe and efficient drilling in high-temperature and complex formations, and has broad application prospects. Detailed Implementation

[0022] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0023] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0024] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0025] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0026] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means an actual value within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0027] This invention first provides an environmentally friendly, high-temperature resistant drilling fluid, wherein each 1L of drilling fluid comprises: 3-12g of viscosity-enhancing and shear-lifting agent; 10-20g of filtration-reducing agent; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 10-30g of plugging agent; and 10-30g of bentonite.

[0028] The thickening and shearing agent has a structure of formula (I); the filtration loss reducing agent has a structure of formula (II); the inhibitor has a structure of formula (III); the wall-strengthening and anti-collapse agent has a structure of formula (IV); and the lubricant has a structure of formula (V).

[0029]

[0030]

[0031] Where a is selected from integers from 7400 to 7600; b, c, d, e, and q are independently selected from integers from 1 to 20; f, h, m, n, s, and t are independently selected from integers from 1 to 10; g is selected from integers from 1200 to 3100; i, j, k, and u are independently selected from integers from 0 to 4; l, o, and r are independently selected from integers from 1 to 3; p is selected from integers from 1 to 30.

[0032] M and N are independently selected from alkali metal elements;

[0033] R1 and R4 are independently selected from C1 to C4. 14 The alkyl group; R2, R3, R5, R6, R7 and R8 are independently selected from C1 to C4 alkyl groups.

[0034] The inventors of this invention have discovered that domestic drilling fluid researchers, considering my country's national conditions, have conducted extensive research and application work in the field of environmentally friendly, high-temperature resistant water-based drilling fluids, achieving significant progress. However, existing water-based drilling fluids suffer from a contradiction where environmental performance and high-temperature resistance cannot be simultaneously achieved. Therefore, this invention adjusts the types and proportions of various environmentally friendly treatment agents in the water-based drilling fluid to obtain a water-based drilling fluid that possesses both environmental performance and high-temperature resistance, thus meeting the requirements for green, safe, and efficient drilling operations in high-temperature and complex formations in areas with high environmental protection requirements. In some specific implementations of this invention, the base fluid of the environmentally friendly, high-temperature resistant drilling fluid is water.

[0035] The environmentally friendly, high-temperature resistant drilling fluid of this invention possesses excellent inhibition, lubrication, temperature resistance, and reservoir protection properties. It is suitable not only for horizontal drilling in highly water-sensitive mudstone and shale-bearing formations prone to collapse, as well as shale gas formations, but also for formations requiring high reservoir protection. Furthermore, the environmentally friendly, high-temperature resistant drilling fluid provided by this invention is water-based, resulting in lower cost, safety, and environmental friendliness. It can be directly discharged and used in formations with high environmental protection requirements.

[0036] In this invention, the thickening and shearing agent is a modified sclerosing dextran MSG with the structure of formula (I). This molecule introduces amide groups, sulfonic acid groups and other structures on the units of sclerosing dextran, thereby exhibiting good high-temperature thickening and shearing performance, while also having a good filtration loss reduction effect.

[0037]

[0038] The selection ranges of a, b, c, d, e, and M are the same as those described above, and will not be repeated here.

[0039] The present invention does not have any special restrictions on the source of the thickening and shearing agent MSG. It can be purchased or synthesized by the individual. For example, it can be prepared by referring to the method provided in the invention patent CN113087846A: a first reaction is carried out with hard dextran, water and hydroxide to obtain a reaction product; acrylic acid, vinylpyrrolidone, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, hydroxide and water are mixed to obtain a mixture; the reaction product and the mixture are carried out a second reaction under the action of an initiator to obtain the thickening and shearing agent MSG.

[0040] In this invention, the filtration loss reducing agent is a modified chitosan AMC with the structure of formula (II). This molecule introduces structures such as carboxymethyl, amino, amide-containing, and sulfonic acid-containing polymer chains on the chitosan units. It not only has excellent resistance to temperature and salt calcium filtration loss, but also has excellent properties such as strong inhibition and high lubrication.

[0041]

[0042] The selection ranges of f, g, h, and N are the same as those described above, and will not be repeated here.

[0043] This invention does not impose any special restrictions on the source of the filtration loss reducing agent AMC; it can be purchased or synthesized independently. For example, it can be prepared using the method provided in invention patent CN107973865A: reacting chitosan, a basic compound, an alcohol compound, and a halocarboxylic acid to obtain the filtration loss reducing agent AMC; wherein the basic compound is an alkali metal hydroxide or an alkali metal carbonate; and the halocarboxylic acid is X-CH2-[CH2]. v -COOH, where X is a halogen and v is an integer selected from 1 to 10.

[0044] In this invention, the inhibitor is an alkyl glycoside derivative SNAPG, which has the molecular structure of formula (III). The molecule introduces functional groups such as polyol, amino group, and sulfonic acid group on the alkyl glycoside unit. It can not destroy the colloidal stability of drilling fluid, but can significantly improve the high temperature stability of drilling fluid and has a strong inhibitory effect. It is a better anti-high temperature collapse inhibitor.

[0045]

[0046] The selection ranges of i, j, k, l, R1, R2, and R3 are the same as those described above, and will not be repeated here.

[0047] The present invention does not impose any special restrictions on the source of the inhibitor SNAPG; it can be purchased or synthesized by the individual. For example, it can be prepared by referring to the method provided in the invention patent CN111320661A: under the action of an acidic catalyst, alkyl glycosides, epoxides, chloroalkyl esters, and a chlorinating agent are reacted in water to obtain a first intermediate product; the first intermediate product is reacted with an organic amine to obtain a second intermediate product; under the action of a catalyst, the second intermediate product is reacted with a chlorinating agent and a sulfonating agent to obtain the inhibitor SNAPG.

[0048] In this invention, the wall-stabilizing and anti-collapse agent is an alkyl glycoside derivative GAPG with a structure of formula (IV). This molecule introduces functional groups such as polyols, amino groups, and silicon groups on the alkyl glycoside unit, so as to achieve the purpose of not destroying the colloidal stability of drilling fluid, significantly improving the high-temperature stability of drilling fluid, and also satisfying the purpose of strong wall-stabilizing and anti-collapse performance.

[0049]

[0050] The selection ranges of m, n, o, p, q, R4, R5, and R6 are the same as those described above, and will not be repeated here.

[0051] The present invention does not impose any special restrictions on the source of the wall-stabilizing and anti-collapse agent GAPG. It can be purchased or synthesized by the user. For example, it can be prepared by referring to the method provided in the invention patent CN111320657A: under the action of an acidic catalyst, alkyl glycosides and epoxychloroalkyl compounds are reacted to obtain chlorool alkyl glycosides; the chlorool alkyl glycosides are reacted with organic amines to obtain aminoalkyl glycosides; under the action of an initiator, the aminoalkyl glycosides are reacted with acrylamide and vinyltrialkoxysilane to obtain the wall-stabilizing and anti-collapse agent GAPG.

[0052] In this invention, the lubricant is an alkyl glycoside derivative LAPG with a structure of formula (V). This molecule introduces functional groups such as polyether, amino, and long-chain sulfonic acid groups onto the alkyl glycoside unit, and has good lubrication performance.

[0053]

[0054] The selection ranges of r, s, t, u, R7, and R8 are the same as those described above, and will not be repeated here.

[0055] This invention does not impose any special restrictions on the source of the lubricant LAPG; it can be purchased or synthesized independently. For example, it can be prepared by referring to the method provided in invention patent CN111320659A: under the action of an acidic catalyst, glyceryl glycoside, epoxide alkyl compound, chlorinating agent and epoxide chloroalkyl compound are reacted to obtain glyceryl glycoside polyether; the glyceryl glycoside polyether is reacted with an organic amine to obtain polyether aminoglyceryl glycoside; the polyether aminoglyceryl glycoside is reacted with sulfonated castor oil to obtain the lubricant LAPG.

[0056] To better utilize the components of the environmentally friendly high-temperature resistant drilling fluid, in some specific implementations, each 1L of the environmentally friendly high-temperature resistant drilling fluid includes: 3-10g of viscosity-enhancing and shear-lifting agent; 10-15g of filtration-reducing agent; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 15-30g of plugging agent; and 10-30g of bentonite.

[0057] Nanoscale calcium carbonate particles possess unique properties such as small size effect and surface effect, enabling them to form thin and dense mud cakes, significantly reducing permeability and effectively minimizing fluid intrusion. This superior plugging performance makes nanoscale calcium carbonate outstanding in sealing microfractures and micropores, thereby improving wellbore stability. Therefore, in some specific implementations of this invention, the plugging agent is nanoscale calcium carbonate. In some specific implementations of this invention, the nanoscale calcium carbonate is preferably nanoscale calcium carbonate that meets the technical requirements of GB / T19590-2011.

[0058] To meet the needs of different regions and types of drilling operations, in some specific implementations of this invention, the environmentally friendly high-temperature resistant drilling fluid also includes a pH adjuster. NaOH has strong pH control capabilities and prevents wellhead collapse, while Na2CO3 has multiple advantages, including adjusting pH, reducing harmful ion concentration, reducing viscosity drop, increasing cleaning ability, and promoting lime hardening. Therefore, in some specific implementations of this invention, the pH adjuster is at least one of NaOH and Na2CO3.

[0059] To increase drilling mud density to balance formation pressure, prevent formation collapse and water inrush, adjust drilling fluid properties to adapt to different formations, improve drilling fluid compressibility, and implement balanced pressure drilling, thereby enhancing drilling safety and efficiency and reducing drilling costs, in some specific implementations of this invention, the environmentally friendly high-temperature resistant drilling fluid also includes a weighting agent. Barite has high density and stable chemical properties, which can significantly increase the density of the drilling fluid, effectively balance formation pressure, and maintain stable density and performance during drilling. Therefore, in some specific implementations of this invention, the weighting agent is barite.

[0060] This invention also provides a method for preparing the above-mentioned environmentally friendly high-temperature resistant drilling fluid, comprising:

[0061] a) Mix bentonite and water evenly and let it stand to cure;

[0062] b) Mix the mixed solution obtained in step a) after static curing with the viscosity improver, filtration reducer, plugging agent, wall-stabilizing and anti-collapse agent, lubricant and inhibitor to obtain an environmentally friendly high-temperature resistant drilling fluid.

[0063] This invention first involves uniformly mixing bentonite and water. In some specific implementations, this uniform mixing is achieved by stirring at a speed of 8000–13000 r / min, preferably 9000–13000 r / min, more preferably 10000–13000 r / min, for 10–30 min, preferably 15–30 min, more preferably 20–30 min. The uniformly mixed solution is then allowed to stand at room temperature for 20–30 h, preferably 22–30 h, more preferably 22–25 h. After obtaining the cured solution, this invention further mixes it uniformly with a viscosity-enhancing and shear-lifting agent, a filtration loss reducer, a plugging agent, a wall-stabilizing and anti-collapse agent, a lubricant, and an inhibitor to obtain the environmentally friendly high-temperature resistant drilling fluid. In some specific implementations, the viscosity-enhancing and shear-lifting agent, filtration loss reducer, plugging agent, wall-stabilizing and anti-collapse agent, lubricant, and inhibitor are added sequentially.

[0064] The environmentally friendly, high-temperature resistant drilling fluid provided by this invention consists mainly of modified chitosan, modified stearin, and various alkyl glycoside derivatives with specific structures. These components work synergistically to enhance viscosity and shear strength, reduce filtration loss, provide strong inhibition, enhance plugging, and provide high lubrication. This helps the environmentally friendly, high-temperature resistant water-based drilling fluid solve problems such as plugging formations with micropores and fractures, solidifying and preventing collapse in fractured formations, and lubrication and preventing sticking in high-friction conditions such as high-density drilling fluids and long horizontal sections. Furthermore, since the main components of the drilling fluid are modified biomass treatment agents, it exhibits excellent high-temperature resistance and environmental performance. (EC) 50 With a value >200,000 mg / L and a temperature resistance of up to 185℃, it helps to achieve green, safe and efficient drilling in high-temperature and complex formations, and has broad application prospects.

[0065] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0066] Example 1

[0067] The thickening and cutting agent MSG was prepared according to the preparation method of patent CN113087846A: 12g of hard dextran, 180g of water, and 4g of sodium hydroxide were added to a polymerization reactor, and the mixture was alkalized and gelatinized at 1000r / min and 60℃ for 0.5h to obtain the reaction product, hard dextran gel; 20g of acrylic acid, 15g of vinylpyrrolidone, 54g of acrylamide, and 27g of... 2-Acrylamide-2-methylpropanesulfonic acid, 6g sodium hydroxide, and 50g water were added to a mixing vessel and stirred at 1000r / min and 30℃ to obtain a monomer aqueous solution. The above-mentioned hard dextran gel was mixed with the monomer aqueous solution and stirred at 1000r / min. The pH of the mixture was adjusted to 8 with 40% sodium hydroxide aqueous solution, and then 0.12g hydrogen peroxide initiator was added. The mixture was reacted at 40℃ for 4h to obtain a milky yellow, semi-transparent, viscous liquid. The liquid was dried and pulverized in an oven at 80℃ to obtain the thickening and shearing agent MSG.

[0068] The filtration loss reducer AMC was prepared according to the preparation method of patent CN113087846A: 16 parts by weight of chitosan (number average molecular weight 200,000), 150 parts by weight of water, 20 parts by weight of sodium hydroxide, and 40 parts by weight of methanol were stirred and mixed evenly. After reacting at 50°C for 0.5 h, 24 parts by weight of chloroacetic acid were added and the mixture was stirred and reacted at 55°C for 2 h. Then, 2 parts by weight of chloroacetic acid were added and the mixture was stirred and reacted at 55°C for 0.5 h. Finally, 2 parts by weight of sodium hydroxide were added until alkaline, and the mixture was stirred and reacted at 80°C for 3 h. The pH of the product obtained from the above reaction was adjusted to neutral, precipitated with 20 parts by weight of acetone, and filtered. The filtered product was then washed with 40 parts by weight of methanol, filtered again, and dried to obtain the filtration loss reducer AMC.

[0069] The inhibitor SNAPG was prepared according to the preparation method of patent CN111320661A: 37g epichlorohydrin, 60g methyl glycoside, 20g ethylene oxide, 45g thionyl chloride, 4g hydrofluoric acid, and 50g water were added to a high-pressure reactor. The mixture was stirred at 600r / min and reacted at 5MPa and 130℃ for 0.5 hours to obtain a first intermediate product. 60g ethylenediamine was added to the first intermediate product, and the mixture was reacted at 60℃ and atmospheric pressure for 3 hours to obtain a second intermediate product. 30g thionyl chloride, 20g fuming sulfuric acid, and 5g urea were added to the second intermediate product, and the mixture was reacted at 66℃ and atmospheric pressure for 3 hours to obtain a reddish-brown transparent viscous liquid. The liquid was then dehydrated to obtain the inhibitor SNAPG.

[0070] The wall-stabilizing and anti-collapse agent GAPG was prepared according to the preparation method of patent CN111320657A: 78g of methyl glycoside, 35g of epichlorohydrin and 3g of hydrofluoric acid were added to a four-necked flask equipped with a reflux condenser and a stirring device. The stirring speed was controlled at 900r / min, and the reaction was carried out at 95℃ for 1 hour to obtain chloromethyl glycoside. 60g of ethylenediamine was added to the above chloromethyl glycoside, and the reaction was carried out at 80℃ and normal pressure for 3 hours to obtain aminomethyl glycoside. 40g of acrylamide and 30g of vinyltrimethoxysilane were added to the above aminomethyl glycoside, and the mixture was stirred evenly at a stirring speed of 900r / min. The pH of the reaction solution was adjusted to 8 with 5g of sodium hydroxide, and 0.8g of ammonium persulfate was added. The reaction was carried out at 50℃ for 3 hours to obtain a light yellow transparent viscous liquid, which is the wall-stabilizing and anti-collapse agent GAPG.

[0071] The lubricant LAPG was prepared according to the preparation method of patent CN111320659A: 102g of glyceryl glycoside, 20g of propylene oxide, 45g of thionyl chloride, 30g of epichlorohydrin, and 4g of hydrochloric acid were added to a four-necked flask equipped with a reflux condenser and a stirrer. The stirring speed was controlled at 900r / min, and the reaction was carried out at 90°C for 2 hours to obtain glyceryl glycoside polyether. 70g of ethylenediamine was added to the above glyceryl glycoside polyether, and the stirring speed was controlled at 900r / min. The reaction was carried out at 70°C and atmospheric pressure for 2 hours to obtain polyether aminoglyceryl glycoside. 150g of sulfonated castor oil was added to the above polyether aminoglyceryl glycoside, and the mixture was stirred thoroughly. Sodium hydroxide was added to adjust the pH of the reaction solution to 9, and the reaction was carried out at 60°C with a stirring speed of 900r / min for 3 hours to obtain a bright red, transparent, viscous liquid, which is the lubricant LAPG.

[0072] Example 2

[0073] (1) In clean water, at 30 kg / m 3 The concentration of bentonite added was 1.5 kg / m³. 3 Add Na2CO3 to the concentration specified, stir at 11,000 rpm for 20 minutes, and then cure at room temperature for 24 hours.

[0074] (2) In the solution obtained in step (1), at 5 kg / m 3 The concentration of the thickening and shearing agent MSG prepared in Example 1 was added, and the mixture was stirred at a stirring speed of 11,000 rpm for 10 minutes.

[0075] (3) In the solution obtained in step (2), at 15 kg / m 3 The concentration of the filtration loss reducer AMC prepared in Example 1 was added, and the mixture was stirred at a stirring speed of 11,000 rpm for 10 minutes.

[0076] (4) In the solution obtained in step (3), at 10 kg / m 3 The wall-stabilizing and anti-collapse agent GAPG prepared in Example 1 was added to the concentration and stirred for 10 minutes at a stirring speed of 11,000 rpm.

[0077] (5) In the solution obtained in step (4), at 10 kg / m 3 The concentration was added to the lubricant LAPG prepared in Example 1, and stirred at a stirring speed of 11,000 rpm for 20 minutes;

[0078] (6) In the solution obtained in step (5), at 30 kg / m 3 Add the sealing agent nano-sized calcium carbonate to the concentration and stir for 10 minutes at a stirring speed of 11,000 rpm;

[0079] (7) In the solution obtained in step (6), at 100 kg / m 3 The concentration of the inhibitor SNAPG prepared in Example 1 was added and stirred at a stirring speed of 11,000 rpm for 20 minutes.

[0080] (8) In the solution obtained in step (7), add 2 kg / m 3 Adding NaOH to a concentration of [specific concentration] will yield a solution with a density of 1.15 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0081] Example 3

[0082] The difference between this embodiment and Embodiment 2 is that the solution obtained in step (8) is further treated with 375 kg / m 3 The concentration of barite was increased to a certain level, and the remaining steps were the same as in Example 2, resulting in a density of 1.4 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0083] Example 4

[0084] The difference between this embodiment and Embodiment 3 is that the concentration of the thickening and cutting agent added in step (2) is 4 kg / m³. 3 In step (7), the concentration of the inhibitor added is 150 kg / m³. 3 The concentration of barite added to the solution obtained in step (8) is 727 kg / m³. 3 The remaining steps were the same as in Example 3, yielding a density of 1.6 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0085] Example 5

[0086] The difference between this embodiment and embodiment 4 is that the concentration of bentonite added in step (1) is 20 kg / m³. 3The concentration of Na2CO3 added is 1 kg / m³. 3 In step (4), the concentration of the wall-stabilizing and anti-collapse agent is 15 kg / m³. 3 In step (5), the concentration of lubricant added is 20 kg / m³. 3 The concentration of barite added to the solution obtained in step (8) is 1138 kg / m³. 3 The remaining steps were the same as in Example 4, yielding a density of 1.8 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0087] Example 6

[0088] The difference between this embodiment and embodiment 5 is that the concentration of bentonite added in step (1) is 15 kg / m³. 3 The concentration of Na2CO3 added was 0.75 kg / m³. 3 In step (2), the concentration of the thickening and cutting agent added is 3 kg / m³. 3 The concentration of barite added to the solution obtained in step (8) is 1623 kg / m³. 3 The remaining steps were the same as in Example 5, yielding a density of 2.0 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0089] Example 7

[0090] The difference between this embodiment and Embodiment 6 is that the concentration of bentonite added in step (1) is 10 kg / m³. 3 The concentration of Na2CO3 added was 0.5 kg / m³. 3 The concentration of the filtration loss reducer added in step (3) is 10 kg / m³. 3 In step (4), the concentration of the wall-stabilizing and anti-collapse agent is 20 kg / m³. 3 The concentration of barite added to the solution obtained in step (8) is 2205 kg / m³. 3 The remaining steps were the same as in Example 6, yielding a density of 2.2 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0091] Example 8

[0092] The difference between this embodiment and Embodiment 7 is that the concentration of the inhibitor added in step (7) is 200 kg / m³. 3 The concentration of barite added to the solution obtained in step (8) is 3335 kg / m³. 3 The remaining steps were the same as in Example 7, yielding a density of 2.5 g / cm³. 3 An environmentally friendly, high-temperature resistant drilling fluid.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 4 is that the thickening and shearing agent was changed from MSG to xanthan gum; all other aspects were the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0095] Comparative Example 2

[0096] The difference between this comparative example and Example 4 is that the filtration loss reducing agent is changed from AMC to polyanionic cellulose LV-PAC. All other aspects are the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0097] Comparative Example 3

[0098] The difference between this comparative example and Example 4 is that the wall-stabilizing and anti-collapse agent is changed from GAPG to complexed aluminum, which meets the technical requirements of Q / SH CG0173-2023. All other aspects are the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0099] Comparative Example 4

[0100] The difference between this comparative example and Example 4 is that the lubricant was changed from LAPG to graphite powder; all other aspects were the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0101] Comparative Example 5

[0102] The difference between this comparative example and Example 4 is that the concentration of the inhibitor SNAPG was increased from 150 kg / m³. 3 Change to 50kg / m 3 Everything else was the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0103] Comparative Example 6

[0104] The difference between this comparative example and Example 4 is that the concentration of the thickening and shearing agent MSG was increased from 4 kg / m³. 3 It becomes 15kg / m 3 Everything else was the same as in Example 4, resulting in a density of 1.6 g / cm³. 3 Drilling fluid.

[0105] Comparative Example 7

[0106] The difference between this comparative example and Example 4 is that the concentration of the filtration loss reducer AMC was increased from 15 kg / m³. 3 Change to 5kg / m 3 Everything else was the same as in Example 4, resulting in a density of 1.6 g / cm³. 3Drilling fluid.

[0107] Experimental Example 1

[0108] The drilling fluids prepared in the above examples and comparative examples were rolled and cured at 185°C for 16 hours, and their mechanical properties were tested at 60°C according to GB / T 16783.1-2014 standard, including density, apparent viscosity (AV), plastic viscosity (PV), shear force (YP), storage modulus to loss modulus ratio (G′ / G″), and API filtration loss (FL). API ), High temperature and high pressure filtration loss (FL) HTHP The results of the calculation of the coefficient of performance and lubrication are shown in Table 1.

[0109] Table 1. Mechanical property tests of drilling fluids prepared in the embodiments and comparative examples of the present invention.

[0110]

[0111] As shown in Table 1, the environmentally friendly high-temperature resistant drilling fluids in Examples 2-8 exhibit good rheological properties after hot rolling, with FL... API FL HTHP The test results were all better than those of comparative examples 1 to 7, and the lubrication coefficient was lower, which is conducive to efficient drilling. This indicates that the synergistic effect among the components in the drilling fluid is significant.

[0112] A comparison of Example 4 with Comparative Examples 1-4 shows that after replacing the treatment agent, the viscosity, shear stress, filtration loss, and lubricity of the drilling fluid changed to varying degrees. HTHP Both the lubrication coefficient and the coefficient of friction are higher than in Example 4, which may lead to complex downhole situations such as stuck pipe and lost circulation during drilling, which is detrimental to safe drilling. This indicates that the selected treatment agents in the environmentally friendly high-temperature resistant drilling fluid provided by this invention have better compatibility in the system and better overall performance.

[0113] A comparison of Example 4 with Comparative Examples 5-7 shows that changing the dosage of the treatment agent altered the apparent viscosity, shear stress, filtration loss, and lubricity of the drilling fluid to varying degrees. Specifically, FL... HTHP The lubrication coefficient is increased to varying degrees, which is not conducive to safe drilling operations. This indicates that the selected treatment agents in the environmentally friendly high-temperature resistant drilling fluid have better compatibility in the drilling fluid system of this invention.

[0114] Experimental Example 2

[0115] According to the relevant content of Q / SH 0687-2016 "Test of Biotoxicity of Chemical Agents in Water-Soluble Drilling Fluids - Luminescent Bacteria Method", the EC values ​​of the drilling fluids prepared in the above examples and comparative examples were tested. 50 The environmental performance was reflected by the value, and the test results are listed in Table 2.

[0116] Table 2. Tests on the high-temperature resistance and environmental performance of drilling fluids prepared in the embodiments and comparative examples of the present invention.

[0117] <![CDATA[EC 50 Value (mg / L) Example 2 293200 Example 3 283700 Example 4 279800 Example 5 283200 Example 6 295400 Example 7 286900 Example 8 292700 Comparative Example 5 271500 Comparative Example 6 269600 Comparative Example 7 265600

[0118] As can be seen from Table 2, the EC values ​​of the drilling fluids prepared in Examples 2-8 and Comparative Examples 5-7 are... 50 The values ​​were all >200,000 mg / L, far exceeding the emission standard of 30,000 mg / L, and the drilling fluids prepared in Examples 2-8 were significantly higher than the EC values ​​in Comparative Examples 5-7. 50 The value has increased, which indicates that the drilling fluid prepared according to the treatment agent provided by the present invention has better environmental performance.

[0119] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An environmentally friendly, high-temperature resistant drilling fluid, characterized in that, Each liter of drilling fluid includes: 3-12g of viscosity improver and shear enhancement agent; 10-20g of filtration reducer; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 10-30g of plugging agent; and 10-30g of bentonite. The thickening and shearing agent has a structure of formula (I); the filtration loss reducing agent has a structure of formula (II); the inhibitor has a structure of formula (III); the wall-strengthening and anti-collapse agent has a structure of formula (IV); and the lubricant has a structure of formula (V). Where a is selected from integers from 7400 to 7600; b, c, d, e, and q are independently selected from integers from 1 to 20; f, h, m, n, s, and t are independently selected from integers from 1 to 10; g is selected from integers from 1200 to 3100; i, j, k, and u are independently selected from integers from 0 to 4; l, o, and r are independently selected from integers from 1 to 3; p is selected from integers from 1 to 30. M and N are independently selected from alkali metal elements; R1 and R4 are independently selected from C1 to C4. 14 The alkyl group; R2, R3, R5, R6, R7 and R8 are independently selected from C1 to C4 alkyl groups.

2. The environmentally friendly high-temperature resistant drilling fluid according to claim 1, characterized in that, Each liter of drilling fluid includes: 3-10g of viscosity improver and shear enhancement agent; 10-15g of filtration reducer; 100-200g of inhibitor; 10-20g of wall-stabilizing and anti-collapse agent; 10-20g of lubricant; 15-30g of plugging agent; and 10-30g of bentonite.

3. The environmentally friendly high-temperature resistant drilling fluid according to claim 1, characterized in that, The sealing agent is nano-sized calcium carbonate.

4. The environmentally friendly high-temperature resistant drilling fluid according to claim 1, characterized in that, Also includes: pH adjuster.

5. The environmentally friendly high-temperature resistant drilling fluid according to claim 4, characterized in that, The pH adjuster is at least one of NaOH and Na2CO3.

6. The environmentally friendly high-temperature resistant drilling fluid according to claim 1, characterized in that, Also includes: Weighting agent.

7. The environmentally friendly high-temperature resistant drilling fluid according to claim 6, characterized in that, The weighting agent is barite.

8. A method for preparing an environmentally friendly, high-temperature resistant drilling fluid, characterized in that, include: a) Mix bentonite and water evenly and let it stand to cure; b) Mix the mixed solution obtained in step a) after static curing with the viscosity improver, filtration reducer, plugging agent, wall-stabilizing and anti-collapse agent, lubricant and inhibitor to obtain an environmentally friendly high-temperature resistant drilling fluid.

9. The preparation method according to claim 8, characterized in that, The specific operation of static curing in step a) is: room temperature curing for 20-30 hours.

10. The preparation method according to claim 8, characterized in that, The specific method for uniformly mixing bentonite and water in step a) is to stir at a stirring speed of 8000-13000 r / min for 10-30 min.

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