Anti-sloughing agent for drilling fluid, preparation method and application thereof

Abstract

This invention discloses an anti-collapse agent for drilling fluids, its preparation method, and its application. The raw materials for the anti-collapse agent include melamine, formaldehyde aqueous solution, organophosphonate, dilute sulfuric acid, water, epichlorohydrin, and a solid acid catalyst. The preparation method of the anti-collapse agent is as follows: 1) Melamine, formaldehyde aqueous solution, and water are mixed evenly, and the pH value of the mixed solution is adjusted to 8-9. Then, the mixture is heated to react and obtain material flow A; 2) Dilute sulfuric acid is introduced into material flow A to react and obtain material flow B; 3) Organophosphonate, solid acid catalyst, and epichlorohydrin are added to material flow B. After the reaction is completed, the mixture is separated and dried to obtain the anti-collapse agent. The anti-collapse agent for drilling fluids provided by this invention has good high-temperature resistance, good salt resistance, temperature resistance, wall solidification, and filtration loss reduction performance. It can meet the requirements of water-based mud anti-collapse and wall solidification in complex well conditions such as deep wells and high-salt brine wells, and extend the safe construction period.

Description

Technical Field

[0001] This invention relates to the field of oilfield exploration and development, specifically to an anti-collapse agent for drilling fluid, its preparation method, and its application. Background Technology

[0002] Currently, with the accelerated pace of oil and gas exploration and development, the number of complex wells, such as deep and ultra-deep wells, is increasing. Problems encountered during drilling in complex formations, such as lost circulation, well collapse, borehole narrowing, and wellbore instability, urgently need to be addressed. High-performance anti-collapse wall-stabilizing agents are key to improving wellbore stability, reducing complex well conditions, and extending the safe construction period. Researchers have conducted extensive studies on high-performance anti-collapse wall-stabilizing agents and reported on the preparation and application of anti-collapse wall-stabilizing agents with different working mechanisms.

[0003] Patent CN104151493A discloses a high-molecular-weight, water-soluble emulsion-type anti-collapse agent obtained through a reverse emulsion method using N-vinylpyrrolidone and (3-methacrylamido)propyltrimethylammonium chloride as polymerizing monomers. CN108456286A discloses an anti-collapse agent prepared by dispersion polymerization using acrylate monomers and acrylic acid as main raw materials, exhibiting good adhesion to wellbore rock particles and effectively improving wellbore strength. CN 108485613A discloses a method for preparing a white asphalt anti-collapse agent, using paraffin wax, stearic acid, glyceryl tristearate, fatty alcohol polyoxyethylene ether, polyethylene glycol monomethyl ether methacrylate, nano-calcium carbonate, and sodium carboxymethyl cellulose as raw materials, obtaining low-fluorescence white asphalt through spray granulation, exhibiting good high-temperature and high-pressure filtration loss reduction performance.

[0004] Based on the above analysis of existing technologies, the existing technologies disclose preparation methods and applications of different types of anti-collapse wall-stabilizing agents. These agents address various aspects, including increasing drilling fluid viscosity, optimizing mud cake quality, reducing filtrate leakage into the formation; reducing water activity, coating, and inhibiting clay hydration swelling, slowing down mud formation and spalling; blocking hydration channels, slowing pressure transmission, and maintaining wellbore stability. All these approaches have achieved certain effects and have focused on the dispersion performance, environmental performance, high-temperature resistance, and fluorescence properties of water-based drilling fluid anti-collapse wall-stabilizing agents to meet the wellbore stability and logging requirements during drilling and production in deep and complex wells. However, existing technologies pay less attention to the salt and calcium resistance properties of anti-collapse wall-stabilizing agents, and further research is needed on anti-collapse agents for high-temperature and high-salinity reservoirs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the main objective of this invention is to provide an anti-collapse agent for drilling fluids, its preparation method, and its application. The anti-collapse agent uses melamine resin as a skeleton and has good salt resistance, temperature resistance, wall-solidifying and filtration loss reduction properties, as well as advantages such as environmental friendliness, low fluorescence, and good water solubility.

[0006] The technical solution of this invention mainly includes the following aspects:

[0007] I. This invention provides an anti-collapse agent for drilling fluids, wherein the raw materials for the anti-collapse agent comprise the following components by weight:

[0008] 12 portions of melamine

[0009] 20-50 parts of formaldehyde aqueous solution

[0010] 10-20 parts of organophosphonates

[0011] 2-12 parts sulfuric acid

[0012] 50-200 parts water

[0013] Epichlorohydrin 2.5–16.5 parts

[0014] 0.05 to 1 part of solid acid catalyst.

[0015] More preferably, the anti-collapse agent raw material comprises the following components in parts by weight:

[0016] 12 portions of melamine

[0017] 28-36 parts of formaldehyde aqueous solution

[0018] 12-18 parts of organophosphonates

[0019] 4-10 parts sulfuric acid

[0020] 100-150 parts water

[0021] Epichlorohydrin 5.5–12.5 parts

[0022] 0.2 to 0.8 parts of solid acid catalyst.

[0023] Furthermore, according to a specific embodiment of the present invention, the concentration of the formaldehyde aqueous solution is 30wt% to 55wt%, specifically, the concentration of the formaldehyde aqueous solution can be 37wt%, 44wt%, or 50wt%, and more preferably an industrial-grade formaldehyde aqueous solution with a concentration of 37wt%.

[0024] Furthermore, according to a specific embodiment of the present invention, the sulfuric acid is dilute sulfuric acid with a concentration of 30% to 50%, preferably 35% to 45%.

[0025] Furthermore, according to a specific embodiment of the present invention, the organophosphonate is selected from one or more of sodium aminotrimethylphosphonate, sodium ethylenediaminetetramethylphosphonate, sodium diallylaminomethylphosphonate, potassium diallylaminomethylphosphonate, calcium diallylaminomethylphosphonate, magnesium diallylaminomethylphosphonate, and sodium diethylenetriaminepentamethylphosphonate.

[0026] Furthermore, according to a specific embodiment of the present invention, the solid acid catalyst is a solid acid catalyst containing Lewis acid sites, specifically selected from one or more of bentonite, montmorillonite, alumina, titanium dioxide, vanadium pentoxide, molybdenum trioxide, aluminum chloride, cation exchange resin, and Y-type molecular sieve; when the catalyst is a cation exchange resin, its framework structure / matrix can be one or more of styrene-based, acrylic-based, urea-formaldehyde-based, phenolic-based, epoxy-based, or vinyl chloride-based, preferably styrene-based cation exchange resin; when the catalyst is a Y-type molecular sieve, it can specifically be one or more of NaY, HY, and USY molecular sieves, preferably USY molecular sieve.

[0027] Furthermore, according to a specific embodiment of the present invention, the anti-collapse agent has a temperature resistance of ≥150℃, a high temperature and high pressure filtration loss (HTHP) of ≤25ml, a NaCl resistance of ≥180000mg / L, and a CaCl2 resistance of ≥60000mg / L.

[0028] Furthermore, according to one specific embodiment of the present invention, the anti-collapse agent is white or light yellow in appearance.

[0029] II. This invention provides a method for preparing an anti-collapse agent for drilling fluid, comprising the following:

[0030] (1) Under mixed conditions, melamine, formaldehyde aqueous solution and water are mixed evenly and the pH value of the mixed solution is adjusted to 8-9. Then the temperature is raised to carry out the reaction to obtain material flow A;

[0031] (2) Under the reaction conditions, dilute sulfuric acid is introduced into the feed stream A obtained in step (1) to carry out the reaction, and feed stream B is obtained after the reaction;

[0032] (3) Under the reaction conditions, organic phosphonate, solid acid catalyst and epichlorohydrin are added to the feed stream B obtained in step (2). After the reaction is completed, the anti-collapse agent is obtained by separation and drying.

[0033] Furthermore, according to a specific embodiment of the present invention, the amounts of melamine, formaldehyde aqueous solution, organophosphonate, dilute sulfuric acid, water, epichlorohydrin, and solid acid catalyst, by weight, are as follows: 12 parts melamine, 20-50 parts formaldehyde, 10-20 parts organophosphonate, 2-12 parts dilute sulfuric acid, 50-200 parts water, 2.5-16.5 parts epichlorohydrin, and 0.05-1 part solid acid catalyst; preferably, 12 parts melamine, 28-36 parts formaldehyde, 12-18 parts organophosphonate, 4-10 parts dilute sulfuric acid, 100-150 parts water, 5.5-12.5 parts epichlorohydrin, and 0.2-0.8 parts solid acid catalyst.

[0034] Furthermore, according to a specific embodiment of the present invention, the reaction conditions in step (1) are as follows: the reaction temperature is 70-90°C and the reaction time is 0.5-6h.

[0035] Furthermore, according to a specific embodiment of the present invention, the pH value of the mixed solution in step (1) can be adjusted to 8-9 by adding an alkaline solution, which can be selected from at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkaline solution is 2 mol / L to 5 mol / L.

[0036] Furthermore, according to a specific embodiment of the present invention, the reaction conditions in step (2) are as follows: the reaction temperature is 50-80°C and the reaction time is 0.5-6h; more preferably, the reaction temperature in step (2) is 10-30°C lower than the reaction temperature in step (1), and more preferably 15-25°C lower.

[0037] Furthermore, according to a specific embodiment of the present invention, the mass concentration of dilute sulfuric acid in step (2) is 30% to 50%, preferably 35% to 45%.

[0038] Furthermore, according to a specific embodiment of the present invention, the organophosphonate in step (3) is selected from one or more of sodium aminotrimethylphosphonate, sodium ethylenediaminetetramethylphosphonate, sodium diallylaminomethylphosphonate, potassium diallylaminomethylphosphonate, calcium diallylaminomethylphosphonate, magnesium diallylaminomethylphosphonate, and sodium diethylenetriaminepentamethylphosphonate.

[0039] Furthermore, according to a specific embodiment of the present invention, the solid acid catalyst in step (3) is a solid acid catalyst containing Lewis acid sites, specifically selected from one or more of bentonite, montmorillonite, alumina, titanium dioxide, vanadium pentoxide, molybdenum trioxide, aluminum chloride, cation exchange resin, and Y-type molecular sieve; when the catalyst is a cation exchange resin, its framework structure / matrix can be one or more of styrene-based, acrylic-based, urea-formaldehyde-based, phenolic-based, epoxy-based, or vinyl chloride-based, preferably styrene-based cation exchange resin; when the catalyst is a Y-type molecular sieve, it can specifically be one or more of NaY, HY, and USY molecular sieves, preferably USY molecular sieve.

[0040] Furthermore, according to a specific embodiment of the present invention, the epichlorohydrin in step (3) is added dropwise.

[0041] Furthermore, according to a specific embodiment of the present invention, the reaction conditions in step (3) are as follows: the reaction temperature is 40-60°C and the reaction time is 0.5-4h.

[0042] Furthermore, according to a specific embodiment of the present invention, the drying temperature in step (3) is 105℃~120℃, and the drying time is 12~48 h.

[0043] Furthermore, according to a specific embodiment of the present invention, the anti-collapse agent obtained in step (3) can be further subjected to crushing treatment to obtain an anti-collapse agent product with the required particle size. The crushing treatment can be carried out by any means existing in the art that can achieve the crushing of solid-phase materials.

[0044] III. The present invention provides a drilling fluid anti-collapse agent prepared by the above preparation method.

[0045] IV. This invention provides an application of the above-mentioned anti-collapse agent for drilling fluid in drilling and production.

[0046] Furthermore, according to a specific embodiment of the present invention, the amount of anti-collapse agent is 0.5 to 5 wt%.

[0047] The technical advantages of the drilling fluid anti-collapse agent and its preparation method provided by this invention are mainly reflected in the following aspects:

[0048] 1. The drilling fluid anti-collapse agent provided by this invention has good high temperature resistance, with a temperature resistance of over 150℃, a high temperature and high pressure filtration loss (HTHP) of no more than 25mL, a NaCl resistance of more than 180,000mg / L, a CaCl2 resistance of more than 60,000mg / L, good salt resistance, high temperature resistance, wall solidification and filtration loss reduction performance, and also has the advantages of being environmentally friendly, low fluorescence and good water solubility. It can meet the requirements of water-based mud anti-collapse and wall solidification in drilling and production of complex well conditions such as deep wells and high-salt brine wells, and extend the safe construction period.

[0049] 2. In the method for preparing drilling fluid anti-collapse agent provided by the present invention, a melamine resin skeleton with aqueous dispersibility is first constructed through the hydroxymethylation reaction and condensation reaction of melamine and formaldehyde. On the basis of the resin skeleton, organophosphonates are added for epoxidative crosslinking to form a composite resin structure with the resin skeleton as the core and the crosslinked organophosphonates as the arms. This enhances the dispersion performance and anti-dehydration performance of traditional resin-based materials in high-temperature and high-salt well mud, so that the resin-based anti-collapse wall-stabilizing agent maintains structural and performance stability under high-temperature and high-salt conditions, and plays an efficient sealing role for nano- and micro-pore throats, thereby improving well wall stability.

[0050] 3. In the method for preparing drilling fluid anti-collapse agent provided by the present invention, the precise control of the branching degree, condensation degree and phosphonic acid group substitution degree of the resin skeleton and the epoxidation modification stage is achieved by adding sulfuric acid and epichlorohydrin dropwise, thus avoiding excessive condensation of resin and excessive crosslinking in phosphonic acid group modification. The reaction process and exothermic reaction are easy to control.

[0051] 4. The anti-collapse agent of this invention can play a good role in preventing collapse, consolidating the wall and reducing filtration loss when applied in water-based mud, especially high-salt brine water-based mud. It has good salt resistance and temperature resistance, low cost, low fluorescence effect, and does not affect logging. It is suitable for use in deep wells, high-salt brine formations and other complex well drilling and production. It has a good effect of sealing and consolidating the wall, blocking the hydration channel, slowing down the pressure transmission effect, and extending the safe construction period. Attached Figure Description

[0052] Figure 1 This is the Raman spectrum of the anti-collapse agent sample obtained in Example 4 of the present invention. Detailed Implementation

[0053] The following specific embodiments further describe the melamine resin-based water-soluble anti-collapse agent, its preparation method, and its application involved in this invention, but do not constitute a limitation on this invention.

[0054] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values ​​stated herein, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0055] In this paper, the Raman spectra of the anti-collapse agent were obtained using a Mettler Toledo React Raman 785 online in-situ Raman spectrometer in the range of 100–3200 cm⁻¹. -1 Obtained by scanning within the wavelength range.

[0056] All material ratios appearing in the following examples and comparative examples are mass fractions of the materials.

[0057] Example 1

[0058] Add 12 parts melamine and 50 parts water to 20 parts of a 50 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the mixed solution to 8.0 with 2 mol / L sodium hydroxide solution. Heat to 70℃ and react at this temperature for 6 hours, maintaining the pH of the system at 8–9. Then cool to 55℃ and add 2 parts of 50 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 6 hours. Then cool to 40℃ and add 0.05 parts aluminum chloride and 10 parts sodium aminotrimethylphosphonate to the system. After thorough mixing, add 2.5 parts epichlorohydrin dropwise. After the addition is complete, react for 4 hours. Discharge the material, centrifuge to remove the aluminum chloride catalyst, and then dry at 105℃ for 48 hours. After pulverization, obtain a pale yellow melamine resin-based water-soluble anti-collapse agent.

[0059] Example 2

[0060] To 36 parts of a 37wt% formaldehyde aqueous solution, add 12 parts of melamine and 150 parts of water. After thorough mixing, adjust the pH of the system to 8.8 with 4mol / L potassium hydroxide solution. Heat to 85℃ and maintain the reaction temperature for 1.5 hours, keeping the pH at 8–9. Then cool to 55℃ and add 10 parts of 33wt% sulfuric acid dropwise. After the addition is complete, react at the same temperature for 1 hour. Next, cool to 48℃ and add 0.8 parts of vinyl chloride-based cation exchange resin and 18 parts of sodium diethylenetriaminepentamethylphosphonate. After thorough mixing, add 12.5 parts of epichlorohydrin dropwise. After the addition is complete, react for 1 hour. Discharge the product, centrifuge to remove the vinyl chloride-based cation exchange resin catalyst, and then dry at 108℃ for 36 hours. After pulverization, obtain a pale yellow melamine resin-based water-soluble anti-collapse agent.

[0061] Example 3

[0062] To 28 parts of a 37wt% formaldehyde aqueous solution, 12 parts of melamine and 100 parts of water were added. After thorough mixing, the pH of the system was adjusted to 8.2 with 2.5mol / L sodium hydroxide solution. The temperature was raised to 74℃ and then kept constant for 3 hours, maintaining the pH of the system at 8-9. The temperature was then lowered to 50℃, and 4 parts of 42wt% sulfuric acid were added dropwise. After the addition was complete, the reaction was continued at the same temperature for 5 hours. The temperature was then lowered to 42℃, and 0.2 parts of montmorillonite and 12 parts of sodium ethylenediaminetetramethylenephosphonate were added. After thorough mixing, 5.5 parts of epichlorohydrin were added dropwise. After the addition was complete, the reaction was continued for 3.5 hours. The product was discharged, centrifuged to remove the montmorillonite catalyst, and then dried at 115℃ for 16 hours. After pulverization, a pale yellow melamine resin-based water-soluble anti-collapse agent was obtained.

[0063] Example 4

[0064] Preparation of sodium diallylaminomethylphosphonate: 5.7 g of phosphorous acid and 7 mL of anhydrous ethanol were added to a reaction vessel. Then, 2 mL of concentrated sulfuric acid (98 wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition completed within 45 min. After the addition was completed, the reaction was refluxed for 2 h. Subsequently, a mixture of 12.6 g of paraformaldehyde and 7 mL of anhydrous ethanol was added dropwise through a constant dropping funnel, with the addition completed within 20 min. After the addition was completed, the reaction was refluxed for 3 h. Then, 5.6 g of sodium hydroxide was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 1 h. After further centrifugation, the obtained solid phase was dried at 80 °C for 10 h to obtain sodium diallylaminomethylphosphonate with a yield of 91.1% and a product purity of 98.5%.

[0065] Add 12 parts melamine and 125 parts water to 35 parts of a 44 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the system to 8.5 with 3 mol / L sodium hydroxide solution. Heat to 82℃ and maintain the reaction temperature for 2 hours, keeping the pH of the system between 8 and 9. Then cool to 57℃ and add 6.5 parts of 35 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 4 hours. Then cool to 50℃ and add 0.6 parts of USY molecular sieve (silicon-aluminum molar ratio...) to the system. n Si : n Al =7.0) and 15 parts of the prepared sodium diallylaminomethylphosphonate were thoroughly stirred and then 10.5 parts of epichlorohydrin were added dropwise. After the addition was completed, the reaction was carried out for 2.5 hours. The product was discharged, centrifuged to remove the USY molecular sieve catalyst, and then dried at 110°C for 24 hours. After pulverization, a light yellow melamine resin-based water-soluble anti-collapse agent was obtained.

[0066] Example 5

[0067] Preparation of calcium diallylaminomethylphosphonate: 11.4 g of phosphorous acid and 7 mL of anhydrous ethanol were added sequentially to a reaction vessel. Then, 7 mL of concentrated sulfuric acid was added to adjust the pH to 1. The reaction vessel was then placed in an ice-water bath. 8.6 mL of diallylamine was added dropwise through a constant-drop funnel, completing the addition within 45 min. After the addition was complete, the reaction was refluxed for 2.5 h. Subsequently, a mixture of 6.3 g of paraformaldehyde and 7 mL of anhydrous ethanol was added dropwise through a constant-drop funnel, completing the addition within 10 min. After the addition was complete, the reaction was refluxed for 1.5 h. Then, 10.0 g of calcium hydroxide was added to adjust the pH to 7, and the reaction was carried out at 20 °C for 2.5 h. After further centrifugation, the resulting solid phase was dried at 80 °C for 10 h to obtain calcium diallylaminomethylphosphonate, with a yield of 90.0% and a purity of 98.2%.

[0068] Add 12 parts melamine and 200 parts water to 50 parts of a 55 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the system to 9.0 with 5 mol / L potassium hydroxide solution. Heat to 90℃ and react at this temperature for 0.5 h, maintaining the pH of the system at 8–9 during this period. Then cool to 80℃ and add 12 parts of 30 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 0.5 h. Then cool to 60℃ and add 1 part alumina and 20 parts calcium diallylaminomethylphosphonate to the system. After thorough mixing, add 16.5 parts epichlorohydrin dropwise. After the addition is complete, react for 0.5 h. Discharge the material, centrifuge to remove the alumina catalyst, and then dry at 120℃ for 12 h. After pulverizing, obtain a pale yellow melamine resin-based water-soluble anti-collapse agent.

[0069] Comparative Example 1

[0070] Add 12 parts melamine and 125 parts water to 35 parts of a 44 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the system to 8.5 with 3 mol / L sodium hydroxide solution. Heat to 85℃ and react at this temperature for 1.5 h, maintaining the pH of the system at 8–9. Then cool to 65℃ and add 6.5 parts of 35 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 4 h. Then cool to 50℃ and add 0.6 parts of USY molecular sieve to the system. After thorough mixing, add 10.5 parts of epichlorohydrin dropwise. After the addition is complete, react for 2.5 h. Discharge the material, centrifuge to remove the catalyst, and then dry at 110℃ for 24 h. After pulverization, obtain a pale yellow melamine resin-based water-soluble anti-collapse agent a.

[0071] Comparative Example 2

[0072] Add 12 parts melamine and 50 parts water to 20 parts of a 50 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the mixture to 8.0 with 2 mol / L sodium hydroxide solution. Heat to 70℃ and react at this temperature for 6 hours, maintaining the pH of the system at 8–9. Then cool to 55℃ and add 2 parts of 50 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 6 hours. Then cool to 40℃ and add 0.05 parts aluminum chloride and 10 parts sodium aminotrimethylphosphonate to the system. Stir thoroughly and react for 4 hours. Discharge the material, centrifuge to remove the aluminum chloride catalyst, and then dry at 105℃ for 48 hours. After pulverization, a pale yellow melamine resin-based water-soluble anti-collapse agent is obtained.

[0073] Comparative Example 3

[0074] Add 12 parts melamine and 50 parts water to 20 parts of a 50 wt% formaldehyde aqueous solution. After thorough mixing, adjust the pH of the mixed solution to 8.0 with 2 mol / L sodium hydroxide solution. Heat to 70℃ and react at this temperature for 6 hours, maintaining the pH of the system at 8–9. Then cool to 55℃ and add 2 parts of 50 wt% sulfuric acid dropwise to the system. After the addition is complete, react at the same temperature for 6 hours. Then cool to 40℃ and add 10 parts of sodium aminotrimethylphosphonate. After thorough mixing, add 2.5 parts of epichlorohydrin dropwise. After the addition is complete, react for 4 hours. Discharge the material, centrifuge to remove the aluminum chloride catalyst, and then dry at 105℃ for 48 hours. After pulverization, obtain a pale yellow melamine resin-based water-soluble anti-collapse agent.

[0075] Performance testing

[0076] 1. Temperature and salt resistance test

[0077] The performance of the anti-collapse agents for drilling fluids obtained in Examples 1-5 and Comparative Examples 1-3 was evaluated using a high-temperature, high-pressure fluid loss analyzer. Experimental apparatus: high-temperature, high-pressure fluid loss analyzer, stirrer, settling vessel, roller furnace. Experimental materials: prepared drilling fluids, samples obtained in Examples 1-5, and samples obtained in Comparative Examples 1-3.

[0078] Experimental steps:

[0079] (1) Preparation of base slurry: Prepare fresh water base slurry by adding water + 5wt% sodium bentonite + 0.3wt% sodium carbonate, and let it stand for 16 hours after preparation.

[0080] (2) Preparation of brine drilling fluid: Prepare brine drilling fluid according to the following formula: base slurry + 0.2wt% FA367 + 1.0wt% DSP-II + 200000 mg / L NaCl + 50000 mg / L CaCl2. After preparation, cure for 24 hours.

[0081] (3) High-temperature aging of drilling fluid: Measure 350g of drilling fluid from step (2), add 2.5 wt% of the example or comparative example sample to the drilling fluid, then put it into a settling tank, place the settling tank into a roller heating furnace, and age the drilling fluid containing the example or comparative example at 150°C for 16h.

[0082] (4) Evaluation of temperature and salt resistance: After cooling the aged drilling fluid to 25°C, put it into the evaluation tank, and then install the evaluation tank on the high temperature and high pressure water loss meter. Turn on the air source and adjust the evaluation pressure to 3.5 MPa, then turn on the air inlet switch and measure the water loss of the drilling fluid during half an hour.

[0083] Experimental results:

[0084] The filtrate loss of the drilling fluid 30 minutes after the start of the evaluation experiment was HTHP. FL The experimental results are shown in Table 1.

[0085] Table 1 Evaluation of Filtration Loss

[0086]

[0087] 2. Anti-collapse and wall-stabilizing performance test

[0088] Drilling fluid was prepared according to step (2) of the temperature and salt resistance test. Shale was dried at 105℃±3℃ and cooled to room temperature (25℃). 50.00g (accurate to 0.01g) of shale particles M0 were weighed and added to 350g of prepared drilling fluid. Then, 2.5wt% of the example or comparative sample was added to the drilling fluid, and after thorough mixing, it was loaded into a settling tank. The settling tank was placed in a 150℃ hot rolling furnace for 16h. After the hot rolling was completed, it was taken out and cooled. Shale particles were recovered using 5-mesh and 10-mesh sieves. After drying at 105℃±3℃ and cooling to room temperature, the mass of the first shale recovery was weighed to obtain the mass M1. The recovered shale was then placed in clean water and loaded into a hot rolling tank. It was hot rolled at 150℃ for 2h. After being taken out, it was dried, recovered and weighed in the same way to obtain the mass M2 of the second shale recovery.

[0089] Then, calculate the primary shale rolling recovery rate R1 = M1 / M0 × 100% and the secondary shale rolling recovery rate R2 = M2 / M1 × 100%.

[0090] Table 2 Evaluation of Shale Rolling Recovery Rate

[0091]

[0092] As shown in Tables 1 and 2, the drilling fluid anti-collapse agents prepared using Examples 1-5 have a significant effect on reducing high-temperature and high-pressure water loss, with the high-temperature and high-pressure water loss being less than 25 mL. They also have a good anti-collapse and wall-stabilizing effect, and the secondary shale rolling recovery rate is higher than 90%. In contrast, the samples prepared using Comparative Examples 1-3 do not have the ability to reduce high-temperature and high-pressure water loss, and the secondary shale rolling recovery rate is below 40%.

Claims

1. A drilling fluid anti-collapse agent, comprising, by weight, the following components: 12 portions of melamine 20-50 parts of formaldehyde aqueous solution 10-20 parts of organophosphonates 2-12 parts sulfuric acid 50-200 parts water Epichlorohydrin 2.5–16.5 parts 0.05–1 part of solid acid catalyst; in, The preparation method of drilling fluid anti-collapse agent includes the following: (1) Under mixed conditions, melamine, formaldehyde aqueous solution and water are mixed evenly and the pH value of the mixed solution is adjusted to 8-9. Then the temperature is raised to carry out the reaction to obtain material flow A; (2) Under the reaction conditions, dilute sulfuric acid is introduced into the feed stream A obtained in step (1) to carry out the reaction, and feed stream B is obtained after the reaction; (3) Under the reaction conditions, organic phosphonate, solid acid catalyst and epichlorohydrin are added to the feed stream B obtained in step (2). After the reaction is completed, the anti-collapse agent is obtained by separation and drying.

2. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: By weight, the anti-collapse agent raw material includes the following components: 12 portions of melamine 28-36 parts of formaldehyde aqueous solution 12-18 parts of organophosphonates 4-10 parts sulfuric acid 100-150 parts water Epichlorohydrin 5.5–12.5 parts 0.2 to 0.8 parts of solid acid catalyst.

3. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The concentration of formaldehyde aqueous solution is 30wt% to 55wt%.

4. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The formaldehyde aqueous solution is a 37wt% industrial-grade formaldehyde aqueous solution.

5. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The sulfuric acid concentration is 30% to 50%.

6. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The sulfuric acid concentration is 35% to 45%.

7. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The organophosphonate is selected from one or more of sodium aminotrimethylphosphonate, sodium ethylenediaminetetramethylphosphonate, sodium diallylaminomethylphosphonate, potassium diallylaminomethylphosphonate, calcium diallylaminomethylphosphonate, magnesium diallylaminomethylphosphonate, and sodium diethylenetriaminepentamethylphosphonate.

8. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The solid acid catalyst is a solid acid catalyst containing Lewis acid sites, selected from one or more of bentonite, montmorillonite, alumina, titanium dioxide, vanadium pentoxide, molybdenum trioxide, aluminum chloride, cation exchange resin, and Y-type molecular sieve.

9. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: When the solid acid catalyst is a cation exchange resin, its framework structure / matrix is ​​one or more of styrene-based, acrylic-based, urea-formaldehyde-based, phenolic-based, epoxy-based, or vinyl chloride-based; when the solid acid catalyst is a Y-type molecular sieve, it is one or more of NaY, HY, and USY molecular sieves.

10. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: When the solid acid catalyst is a cation exchange resin, its framework / matrix is ​​a styrene-based cation exchange resin; when the solid acid catalyst is a Y-type molecular sieve, it is a USY molecular sieve.

11. A method for preparing the anti-collapse agent for drilling fluid according to any one of claims 1-10, comprising the following: (1) Under mixed conditions, melamine, formaldehyde aqueous solution and water are mixed evenly and the pH value of the mixed solution is adjusted to 8-9. Then the temperature is raised to carry out the reaction to obtain material flow A; (2) Under the reaction conditions, dilute sulfuric acid is introduced into the feed stream A obtained in step (1) to carry out the reaction, and feed stream B is obtained after the reaction; (3) Under the reaction conditions, organic phosphonate, solid acid catalyst and epichlorohydrin are added to the feed stream B obtained in step (2). After the reaction is completed, the anti-collapse agent is obtained by separation and drying.

12. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The amounts of melamine, formaldehyde aqueous solution, organophosphonate, dilute sulfuric acid, water, epichlorohydrin, and solid acid catalyst, by weight, are as follows: 12 parts melamine, 20-50 parts formaldehyde, 10-20 parts organophosphonate, 2-12 parts dilute sulfuric acid, 50-200 parts water, 2.5-16.5 parts epichlorohydrin, and 0.05-1 part solid acid catalyst.

13. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The amounts of melamine, formaldehyde aqueous solution, organophosphonate, dilute sulfuric acid, water, epichlorohydrin, and solid acid catalyst, by weight, are as follows: 12 parts melamine, 28-36 parts formaldehyde, 12-18 parts organophosphonate, 4-10 parts dilute sulfuric acid, 100-150 parts water, 5.5-12.5 parts epichlorohydrin, and 0.2-0.8 parts solid acid catalyst.

14. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The reaction conditions in step (1) are as follows: the reaction temperature is 70-90℃ and the reaction time is 0.5-6h.

15. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: In step (1), the pH of the mixed solution is adjusted to 8-9 by adding an alkaline solution. The alkaline solution is selected from at least one of sodium hydroxide and potassium hydroxide, and the concentration of the alkaline solution is 2 mol / L to 5 mol / L.

16. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The reaction conditions in step (2) are as follows: the reaction temperature is 50-80℃ and the reaction time is 0.5-6h.

17. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The reaction temperature in step (2) is 10 to 30°C lower than the reaction temperature in step (1).

18. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The reaction temperature in step (2) is 15-25°C lower than the reaction temperature in step (1).

19. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The mass concentration of dilute sulfuric acid in step (2) is 30% to 50%.

20. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The mass concentration of dilute sulfuric acid in step (2) is 35% to 45%.

21. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The organophosphonate in step (3) is selected from one or more of sodium aminotrimethylphosphonate, sodium ethylenediaminetetramethylphosphonate, sodium diallylaminomethylphosphonate, potassium diallylaminomethylphosphonate, calcium diallylaminomethylphosphonate, magnesium diallylaminomethylphosphonate, and sodium diethylenetriaminepentamethylphosphonate.

22. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The solid acid catalyst in step (3) is a solid acid catalyst containing Lewis acid sites, selected from one or more of bentonite, montmorillonite, alumina, titanium dioxide, vanadium pentoxide, molybdenum trioxide, aluminum chloride, cation exchange resin, and Y-type molecular sieve; when the catalyst is a cation exchange resin, its framework structure / matrix is ​​one or more of styrene-based, acrylic-based, urea-formaldehyde-based, phenolic-based, epoxy-based, or vinyl chloride-based; when the catalyst is a Y-type molecular sieve, it is one or more of NaY, HY, and USY molecular sieves.

23. The method for preparing the anti-collapse agent for drilling fluid according to claim 22, characterized in that: When the catalyst is a cation exchange resin, its framework / matrix is ​​a styrene-based cation exchange resin; when the catalyst is a Y-type molecular sieve, it is a USY molecular sieve.

24. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The reaction conditions in step (3) are as follows: the reaction temperature is 40-60℃ and the reaction time is 0.5-4h.

25. The method for preparing the anti-collapse agent for drilling fluid according to claim 11, characterized in that: The drying temperature in step (3) is 105℃~120℃, and the drying time is 12~48 h.

26. A drilling fluid anti-collapse agent obtained by the preparation method according to any one of claims 11-25.

27. The application of the drilling fluid anti-collapse agent according to any one of claims 1-10 and the drilling fluid anti-collapse agent obtained by the preparation method according to any one of claims 11-25 in drilling and production.

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