Long-acting temperature-resistant plugging-while-drilling drilling fluid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oilfield chemical plugging, and discloses a long-acting temperature-resistant plugging-while-drilling drilling fluid as well as a preparation method and application thereof. The long-acting temperature-resistant plugging-while-drilling drilling fluid comprises a basic drilling fluid and a plugging agent, and the plugging agent comprises a granular material, a flaky material, a fibrous material and an elastic material; the mass ratio of the granular material to the flaky material to the fibrous material to the elastic material is (10-14): (4-7): (4-6): (3-5); the long-acting temperature-resistant plugging-while-drilling drilling fluid disclosed by the invention is high in temperature resistance and long in pressure bearing time in a high-temperature and high-pressure environment, and can be applied to water-based drilling fluid and oil-based drilling fluid; and the long-acting temperature-resistant plugging-while-drilling drilling fluid can bear pressure for 7 days at the high temperature of 230 DEG C and the pressure of 12.0 MPa, so that the problems of high-temperature and high-pressure underground permeability leakage and leakage of tiny apertures are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemical plugging, and in particular to a long-acting temperature-resistant drilling fluid for plugging leaks while drilling, and a preparation method and application thereof. Background Art

[0002] Well leakage has always been one of the bottleneck problems restricting the stability of the wellbore. Leakage often causes a series of complex situations. In the mildest case, a large amount of drilling fluid is lost, which consumes a lot of financial and material resources; in the worst case, it leads to drill jamming and even wellbore scrapping. With the continuous deepening of oil and gas resource exploration and development, the number of deep wells and ultra-deep wells continues to increase, and high-temperature and high-pressure leakage formations and broken formations encountered in drilling continue to appear. According to statistics from the high-temperature and high-pressure leakage wells that have been drilled, the leakage channels are mostly pores and fine cracks. Therefore, the technology of plugging leakage while drilling under high temperature needs to be solved.

[0003] At present, there are three types of plugging materials used while drilling. One is ultra-low permeability treatment agent. Ultra-low permeability treatment agent is a synthetic polymer material that can form associated colloids. It can soften and deform at a certain temperature and pressure to form a tight seal for high permeability formations. It has a significant role in preventing and plugging while drilling when drilling pressure-depleted formations, formations with developed fractures, high permeability formations, and long open hole multi-set pressure formations. However, it was found during the field application process that the ultra-low permeability treatment agent has small particles and can only have a good plugging effect on nano-micron-level pores and cracks. The plugging effect is poor when drilling larger-level pores and cracks; in addition, the ultra-low permeability treatment agent has poor temperature resistance and can generally only resist temperatures of about 150°C. When the bottom hole temperature is higher than 160°C, the plugging effect on deep wells and ultra-deep well formations is significantly weakened; and the ultra-low permeability treatment agent is polymerized by organic polymers and soluble in oil, so it can only be used in water-based drilling fluids, and its application range is limited.

[0004] The second is polymer gel plugging technology. Polymer gel is a three-dimensional cage-like viscoelastic body formed by cross-linking macromolecular polymers. This viscoelastic body has strong deformability and can enter cracks and pore spaces without being restricted by leakage channels through extrusion deformation, and stay at the leakage layer position. It forms a plugging layer through solidification reaction or body expansion at the leakage layer position. Polymer gel plugging technology is not widely used on site at present, and most of them are in the experimental stage. This is mainly due to the following two reasons. First, there are many factors affecting the gelation of polymer gel. The drilling fluid system is a complex liquid environment with organic molecules, inorganic salts and inert solids. These have a great influence on the gelation time of polymer gel, resulting in the inability of the plugging material to accurately enter the leakage layer position to gel; second, there are metal ions in the formation, and under high temperature and high pressure environment, the strength of the gel cannot be guaranteed, and the ion types and concentrations in different block formations are different. Therefore, the gel plugging agent cannot adapt to the changing downhole environment, and many uncertain factors easily cause waste of plugging materials. More seriously, the premature solidification of a large amount of gel material can easily lead to complex accidents such as drill stuck.

[0005] The third type is the conventional composite while-drilling plugging agent, which is mostly made of rigid granular materials such as calcium carbonate and coke particles, fiber materials (sawdust, walnut shells, cottonseed shells, peanut shells, straw, Reite fiber and reed, etc.) and ordinary rubber flexible deformation materials. These while-drilling plugging materials can play a good role in preventing leakage and plugging when the bottom hole temperature is lower than 150°C. However, when the bottom hole temperature is higher than 150°C, plant fiber materials such as sawdust, walnut shells, cottonseed shells, peanut shells, straw, etc. are directly carbonized into powder; Reite fiber becomes brittle directly after the temperature is higher than 150°C, and becomes powder crystals when a little pressure is applied; although ordinary rubber has good elasticity and toughness at room temperature and high compression resistance, when the temperature is higher than 160°C, the flexibility and strength of ordinary rubber are significantly reduced. Therefore, the pressure-bearing time of using such a composite while-drilling plugging agent is short, and repeated plugging is required, which prolongs the drilling cycle, reduces drilling efficiency, and cannot meet the needs of long-term pressure-bearing plugging under high temperature and high pressure conditions. The conventional plugging-while-drilling technology has a short pressure-bearing time, especially in high-temperature and high-pressure formations, which cannot meet the needs of engineering drilling.

[0006] Chinese patent document CN113122202A discloses a high temperature resistant plugging agent while drilling and its preparation method, which is prepared by granular material, flaky material, fibrous material and elastic material in a mass ratio of 5:2:2:1, wherein the granular material is coke particles, diatomaceous earth, calcium carbonate, the flaky material is mica flakes, the fibrous material is glass fiber or asbestos fiber, and the elastic material is the product of vulcanization of low phenyl silicone rubber; further analysis of the patent shows that:

[0007] (1) The granular materials in this patent are calcium carbonate, diatomaceous earth and coke particles. Calcium carbonate particles are acidic substances with positive charges on their surface. The drilling fluid system is an alkaline environment. In the alkaline medium, the positive charges on the surface of calcium carbonate are neutralized, and the calcium carbonate particles are gradually dissolved, releasing CO. 2 Gas, therefore, the shape of calcium carbonate particles will change in the drilling fluid and cannot maintain a long-term and lasting pressure-bearing state; diatomite is a collection of tiny diatom remains, with a large porosity and easy absorption of water, which makes diatomite have a certain elasticity and reduces its hardness; secondly, diatomite has a certain solubility in alkaline solution; thirdly, diatomite is an inorganic substance, and its shape begins to change when the temperature is higher than 150°C, and cracking and deformation occur; coke particles are loose and porous, brittle, and their hardness decreases at high temperatures, and they cannot meet the requirements of long-term plugging under high temperature and high pressure;

[0008] (2) The elastic material in the patent is a product of low-phenyl silicone rubber vulcanization; after vulcanization, the elasticity, heat resistance and tensile strength of low-phenyl silicone rubber are increased, and the temperature resistance is good. However, the low-phenyl vulcanized silicone rubber has poor oil erosion resistance. When the oil-based drilling fluid is used for plugging construction, it cannot withstand pressure for a long time under high temperature and high pressure; secondly, the density of low-phenyl vulcanized silicone rubber is 1.0g / cm 3 ~1.30g / cm 3 When the density is greater than 1.50g / cm 3 When using drilling fluid for plugging operations, low-phenyl sulfide silicone will float on the surface of the drilling fluid. When drilling into a leaking layer, only a small amount of low-phenyl sulfide silicone will enter the pores with the drilling fluid, and it will not play a role in plugging the pores.

[0009] (3) The plugging agent in the patent is prepared from granular material, sheet material, fibrous material and elastic material in a mass ratio of 5:2:2:1, and the mass percentage of the total amount of the plugging agent in the drilling fluid is not limited. It is well known that only when the plugging agent reaches a certain concentration in the drilling fluid can the plugging agent bridge, fill and seal the pores and cracks in the leaking layer; otherwise, if the plugging agent concentration is too low, it cannot form a tight accumulation at the pores and cracks at the bottom of the well, and the plugging effect on the leaking layer is poor, resulting in the loss of a large amount of drilling fluid;

[0010] Comprehensive analysis shows that the patent can withstand high pressure in a short period of time at a temperature of 220°C to carry out plugging operations. However, the hardness and brittleness of the particles in the plugging agent decrease over time, and the total mass concentration of the plugging agent is uncertain. Therefore, the drilling fluid prepared with the plugging agent described in the patent cannot withstand pressure for a long time, and the plugging success rate is low, forcing repeated plugging operations. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a long-lasting temperature-resistant while-drilling plugging drilling fluid and a preparation method thereof in response to the leakage occurring during the construction of high-temperature and high-pressure wells, the poor plugging effect of the plugging agents used in the existing drilling fluids, and the limited application fields.

[0012] The long-acting temperature-resistant and leak-on-drilling plugging drilling fluid of the present invention has strong temperature resistance and a long pressure-bearing time under high temperature and high pressure environment, and can be applied to water-based drilling fluid and oil-based drilling fluid; and the long-acting temperature-resistant and leak-on-drilling plugging drilling fluid can withstand pressure for 7 days under a high temperature of 230° C. and a pressure of 12 MPa, effectively solving the problem of permeability leakage and leakage in tiny pores in high temperature and high pressure wells.

[0013] In order to solve the above technical problems, the first aspect of the present invention provides a long-lasting temperature-resistant drilling fluid for plugging leaks while drilling, comprising a basic drilling fluid and a plugging agent, wherein the plugging agent comprises a granular material, a flaky material, a fibrous material and an elastic material; the mass ratio of the granular material, the flaky material, the fibrous material and the elastic material is (10-14): (4-7): (4-6): (3-5).

[0014] According to some embodiments of the present invention, the granular material is selected from quartz sand or modified quartz sand.

[0015] According to some embodiments of the present invention, the method for preparing modified quartz sand includes physical modification and chemical modification performed sequentially; preferably, the physical modification is shot peening; and the chemical modification is coating bisphenol A epoxy resin on the surface of quartz sand by a thermal method. The specific process is as follows: quartz sand is shot peened with 40-60 mesh steel shot under compressed air power to achieve surface grinding; wherein, the shot peening time is 120 seconds and the shot peening frequency is 50HZ; then the shot peened quartz sand is heated to 180°C and poured into a sand mixer, the sand mixer is stirred at a speed of 300r / min, bisphenol A epoxy resin is added to the sand mixer, and stirring is continued for 8 minutes to allow the functional groups such as Si-OH (silanol group) and Si-O-Si (silyl ether group) on the surface of the quartz sand to fully react with the epoxy groups in the bisphenol A epoxy resin, the heating is stopped, and then a 25% mass concentration of hexamethylenetetramine aqueous solution is added and stirring is continued for 5 minutes, and the modified quartz sand is obtained by screening after cooling; wherein, the mass ratio of quartz sand, bisphenol A epoxy resin and hexamethylenetetramine is 250:5:1.

[0016] According to some embodiments of the present invention, the particle size of the granular material is 20 mesh to 100 mesh.

[0017] According to some embodiments of the present invention, the sheet material is a mica sheet.

[0018] According to some embodiments of the present invention, the particle size of the flaky material is 80 mesh to 150 mesh.

[0019] According to some embodiments of the present invention, the fibrous material is selected from at least one of glass fiber and asbestos fiber.

[0020] According to some embodiments of the present invention, the particle size of the fibrous material is 55 mesh to 80 mesh.

[0021] According to some embodiments of the present invention, the elastic material is fluorosilicone rubber.

[0022] According to some embodiments of the present invention, the particle size of the elastic material is 150 mesh to 300 mesh.

[0023] According to some embodiments of the present invention, the base drilling fluid is a water-based drilling fluid and / or an oil-based drilling fluid.

[0024] According to some embodiments of the present invention, based on the volume of the long-acting temperature-resistant while-drilling plugging drilling fluid being 100%, the mass percentage of the plugging agent is 21% to 30%.

[0025] The second aspect of the present invention provides a method for preparing the long-lasting temperature-resistant while-drilling plugging drilling fluid provided by the first aspect, comprising sequentially adding the granular material, flaky material, fibrous material and elastic material into the base drilling fluid.

[0026] According to some embodiments of the present invention, the preparation method comprises:

[0027] (1) Add granular materials to the base drilling fluid through a feeding funnel and stir for 10 to 15 minutes to evenly disperse the granular materials in the drilling fluid system;

[0028] (2) Continue to add the flake material through the feeding funnel and stir for 10 to 15 minutes to evenly disperse the flake material in the drilling fluid system;

[0029] (3) Continue to add fibrous materials through the feeding funnel and stir for 15 to 20 minutes to evenly disperse the fibrous materials in the drilling fluid system;

[0030] (4) Continue to add the elastic material through the feeding funnel and stir for 20 minutes to 30 minutes to evenly disperse the elastic material in the drilling fluid system to obtain a long-lasting temperature-resistant while-drilling plugging drilling fluid.

[0031] According to some embodiments of the present invention, the preparation method comprises:

[0032] (1) Add granular material to the base drilling fluid through a feeding funnel and stir for 10 minutes to evenly disperse the granular material in the drilling fluid system;

[0033] (2) Continue to add the flake material through the feeding funnel and stir for 10 minutes to evenly disperse the flake material in the drilling fluid system;

[0034] (3) Continue to add fibrous material through the feeding funnel and stir for 20 minutes to evenly disperse the fibrous material in the drilling fluid system;

[0035] (4) Continue to add the elastic material through the feeding funnel and stir for 25 minutes to evenly disperse the elastic material in the drilling fluid system to obtain a long-lasting temperature-resistant while-drilling plugging drilling fluid.

[0036] The third aspect of the present invention provides the use of the long-acting temperature-resistant and leak-proof drilling fluid provided by the first aspect or the long-acting temperature-resistant and leak-proof drilling fluid prepared by the preparation method provided by the second aspect in drilling.

[0037] Aiming at the leakage problem occurring during the construction of high-temperature and high-pressure wells, the present invention provides a long-acting temperature-resistant while-drilling plugging drilling fluid according to the "one-third and one-half" bridging of granular and flaky materials, entanglement of fibrous materials, and plugging of elastic materials in plugging technology; compared with conventional while-drilling plugging drilling fluid, the long-acting temperature-resistant while-drilling plugging drilling fluid of the present invention has the following beneficial effects:

[0038] (1) Conventional plugging agents for drilling are made of plugging materials such as sawdust, walnut shells and conventional rubber, and their temperature resistance does not exceed 150°C. However, the long-lasting temperature-resistant plugging drilling fluid for drilling according to the present invention can withstand temperatures above 230°C and can withstand pressure for a long time under high temperature and high pressure environments;

[0039] (2) Since the elastic material used in conventional drilling plugging agents is ordinary rubber, which dissolves in oil, conventional drilling plugging agents can only be applied to water-based drilling fluids, while the elastic material used in the long-lasting temperature-resistant drilling plugging drilling fluid of the present invention is fluorosilicone rubber, which does not dissolve in oil. Therefore, the long-lasting temperature-resistant drilling plugging drilling fluid of the present invention can be applied to both water-based drilling fluids and oil-based drilling fluids, and can be used for drilling plugging of deep wells, ultra-deep wells and geothermal wells; in addition, the density of conventional rubber is 0.8 g / cm 3 ~1.3g / cm 3 Between, when the density is higher than 1.30g / cm 3 The fluorosilicone rubber used in the present invention has a density of 1.90 g / cm 3 ~2.10g / cm 3 It can enter the drilling fluid and enter the pores of the formation along with the drilling fluid, thus plugging the leaking layer;

[0040] (3) Conventional plugging while drilling agents are simply a combination of materials of various shapes, while the long-lasting temperature-resistant plugging while drilling drilling fluid of the present invention contains silicon-oxygen bonds in its material structure, which can react chemically at high temperature and pressure at the bottom of the well and be bonded together by silicon-oxygen-silicon chemical bonds;

[0041] (4) The long-lasting temperature-resistant and leak-proof drilling fluid for drilling while plugging has long-lasting temperature resistance. The long-lasting temperature-resistant and leak-proof drilling fluid for drilling while plugging can withstand pressure for 7 days at a high temperature of 230°C and a pressure of 12MPa. It can be used for leak-proof drilling during the construction of deep wells, ultra-deep wells and geothermal wells. It can quickly and effectively seal permeability leaks and leaks in tiny pores and seams, thus avoiding repeated leak-proofing operations. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0043] In the following examples and comparative examples of the present invention, unless otherwise specified, various raw materials and instruments used are commercially available and are common reagents or common instruments that can be purchased by those skilled in the art.

[0044] Unless otherwise specified, the high-temperature and high-pressure sand bed filter loss tester and the high-temperature and high-pressure micro-fracture plugging tester used in the preparation examples of the present invention are commercially available.

[0045] In the examples and comparative examples, the % mentioned in the drilling fluid preparation process refers to the mass percentage of each component in the total volume of the prepared drilling fluid.

[0046] High temperature and high pressure sand bed filter loss tester experimental operation process:

[0047] Step 1: Add the prepared drilling fluid for plugging while drilling into the high-temperature and high-pressure sand bed filter loss tester (the sand bed is composed of quartz sand with a particle size of 0.45mm to 1.5mm and a sand bed thickness of 25mm), tighten the sealing cover, and connect the high-pressure manifold;

[0048] Step 2: Heat to 230℃ and keep constant temperature for 10min;

[0049] Step 3: Open the high-pressure manifold and increase the pressure at a rate of 0.2MPa every 5 minutes, gradually increasing the pressure to 12.0MPa;

[0050] Step 4: During the pressurization process, if the sand bed is penetrated, the pressure value when the sand bed is penetrated is recorded, which is the pressure bearing capacity of the drilling fluid for plugging while drilling;

[0051] Step 5: When the pressure reaches 12.0 MPa, stop pressurizing and stabilize the pressure at 12.0 MPa until 7 days. During the pressure stabilization period, if the sand bed is broken through, record the pressure stabilization time, i.e. the pressure bearing time, and collect the volume of drilling fluid that passes through the sand bed after 30 minutes of pressure bearing.

[0052] Step 6: During the period of stabilizing the pressure at 12.0 MPa until 7 days, if the sand bed is not penetrated, collect the volume of drilling fluid that penetrates the sand bed after 30 minutes of pressure and 7 days of pressure, and calculate the leakage rate after 30 minutes of pressure and 7 days of pressure;

[0053] Among them, 30-minute leakage rate = the volume of drilling fluid that passes through the sand bed under pressure for 30 minutes / the total volume of drilling fluid * 100%; 7-day leakage rate = the volume of drilling fluid that passes through the sand bed under pressure for 7 days / the total volume of drilling fluid * 100%.

[0054] High temperature and high pressure micro crack plugging instrument experimental operation process:

[0055] Step 1: Add the prepared drilling fluid into the high temperature and high pressure micro-crack plugging instrument, tighten the sealing cover, and connect the high pressure manifold;

[0056] Step 2: Heat to 230℃ and keep constant temperature for 10min;

[0057] Step 3: Open the high-pressure manifold and increase the pressure at a rate of 0.2MPa every 5 minutes, gradually increasing the pressure to 12.0MPa;

[0058] Step 4: During the pressurization process, if the seam plate is penetrated, the pressure value when the seam plate is penetrated is recorded, which is the pressure bearing capacity of the drilling fluid for plugging while drilling;

[0059] Step 5: When the pressure reaches 12.0 MPa, stop pressurizing and stabilize the pressure at 12.0 MPa until 7 days. During the pressure stabilization period, if the seam plate is broken, record the pressure stabilization time, i.e. the pressure bearing time, and collect the volume of drilling fluid that passes through the seam plate after 30 minutes of pressure bearing;

[0060] Step 6: During the period of stabilizing the pressure at 12.0 MPa until 7 days, if the seam plate is not penetrated, collect the volume of drilling fluid that passes through the seam plate for 30 minutes and 7 days under pressure, and calculate the leakage rate for 30 minutes and 7 days under pressure;

[0061] Among them, 30min leakage rate = drilling fluid volume that passes through the seam plate under pressure for 30min / total drilling fluid volume*100%; 7d leakage rate = drilling fluid volume that passes through the seam plate under pressure for 7d / total drilling fluid volume*100%.

[0062] In the embodiments and comparative examples, the preparation process of modified quartz sand is:

[0063] Quartz sand is shot peened with 40-60 mesh steel shots under compressed air power to achieve surface grinding; wherein, the shot peening time is 120 seconds and the shot peening frequency is 50 Hz; then the shot peened quartz sand is heated to 180°C and poured into a sand mixer, the sand mixer is stirred at a speed of 300 r / min, bisphenol A epoxy resin is added to the sand mixer, and stirring is continued for 8 minutes to allow functional groups such as Si-OH (silanol group) and Si-O-Si (silyl ether group) on the surface of the quartz sand to fully react with epoxy groups in the bisphenol A epoxy resin, the heating is stopped, and then a 25% mass concentration of hexamethylenetetramine aqueous solution is added and stirring is continued for 5 minutes, and the modified quartz sand is obtained by screening after cooling; wherein, the mass ratio of quartz sand, bisphenol A epoxy resin and hexamethylenetetramine is 250:5:1. After the quartz sand is modified, the roughness of the quartz sand is improved, and the adhesion is strong at high temperature, which increases the sealing effect of the plugging material at the pores.

[0064] Example 1

[0065] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0066] The plugging agent includes modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20-100 meshes; the particle size of the mica flakes is 80-150 meshes; the particle size of the asbestos fibers is 55-80 meshes; and the particle size of the fluorosilicone rubber is 150-300 meshes.

[0067] The long-term temperature-resistant water-based drilling fluid for plugging while drilling is prepared with the following formula: 400 mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then use barite to increase the weight to 1.50 g / cm 3 , add 13.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes, then add it to the high temperature and high pressure sand bed filter loss instrument for experiment. The pressure-bearing plugging effect is shown in Table 1.

[0068] Example 2

[0069] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0070] The plugging agent includes modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the glass fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0071] The long-term temperature-resistant water-based drilling fluid for plugging while drilling is prepared with the following formula: 800 mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50 g / cm 3 , add 13.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% glass fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into two equal parts and added into the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 1.

[0072] Example 3

[0073] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0074] The plugging agent includes modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20-100 meshes; the particle size of the mica flakes is 80-150 meshes; the particle size of the asbestos fibers is 55-80 meshes; and the particle size of the fluorosilicone rubber is 150-300 meshes.

[0075] The long-term temperature-resistant water-based drilling fluid for plugging while drilling is prepared with the following formula: 400 mL water + 1.8% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 0.8% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 2.00 g / cm 3 , add 12.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 4.8% mica flakes and stir for 10 minutes; continue to add 4.8% asbestos fiber and stir for 20 minutes, then continue to add 3.6% fluorosilicone rubber and stir for 25 minutes, then add it to the high temperature and high pressure sand bed filter loss instrument for experiment. The pressure-bearing plugging effect is shown in Table 1.

[0076] Example 4

[0077] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0078] The plugging agent includes modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the glass fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0079] The long-term temperature-resistant water-based drilling fluid for plugging while drilling is prepared with the following formula: 800 mL water + 1.8% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 0.8% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add weight to 2.00 g / cm 3 , add 12.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 4.8% mica flakes and stir for 10 minutes; continue to add 4.8% glass fiber and stir for 20 minutes, then continue to add 3.6% fluorosilicone rubber and stir for 25 minutes. Then, divide the drilling plugging water-based drilling fluid into two equal parts and add it to the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 1.

[0080] Table 1 Pressure bearing capacity of different embodiments in water-based drilling fluid for plugging while drilling

[0081]

[0082] It can be seen from Table 1 that, under the condition of a temperature of 230°C, whether it is a quartz sand bed of 0.45 mm to 1.5 mm or cracks with a width of 0.5 mm and 1.0 mm, the long-acting temperature-resistant water-based drilling fluid for plugging leaks while drilling prepared by Examples 1-4 of the present invention has good pressure-bearing plugging ability, and the pressure-bearing plugging time can be maintained for 7 days, and the leaking layer can be plugged for a long time.

[0083] Example 5

[0084] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0085] The plugging agent includes modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20-100 meshes; the particle size of the mica flakes is 80-150 meshes; the particle size of the asbestos fibers is 55-80 meshes; and the particle size of the fluorosilicone rubber is 150-300 meshes.

[0086] The formula for preparing long-term temperature-resistant oil-based drilling fluid for plugging while drilling is: 400mL (320mL base oil + 80mL calcium chloride aqueous solution, where the calcium chloride concentration is 25%) + 3.0% primary emulsifier + 2.0% auxiliary emulsifier + 3.5% organic soil + 2.0% wetting agent + 3.5% oil-based fluid loss reducer + 4.0% oil-based drilling fluid high temperature resistant plugging agent + 2.0% lime, and then use barite to increase the weight to 1.50g / cm 3 , add 14.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.6% mica flakes and stir for 10 minutes; continue to add 5.6% asbestos fiber and stir for 20 minutes, then continue to add 4.2% fluorosilicone rubber and stir for 25 minutes, then add it to the high temperature and high pressure sand bed filter loss instrument for experiment. The pressure-bearing plugging effect is shown in Table 2.

[0087] Example 6

[0088] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0089] The plugging agent includes modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the glass fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0090] The formula for preparing long-term temperature-resistant oil-based drilling fluid for plugging while drilling is as follows: 800 mL (640 mL base oil + 160 mL calcium chloride aqueous solution, where the calcium chloride concentration is 25%) + 3.0% primary emulsifier + 2.0% auxiliary emulsifier + 3.5% organic soil + 2.0% wetting agent + 3.5% oil-based fluid loss reducer + 4.0% oil-based drilling fluid high temperature resistant plugging agent + 2.0% lime, and then use barite to increase the weight to 1.50 g / cm 3, add 14.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.6% mica flakes and stir for 10 minutes; continue to add 5.6% glass fiber and stir for 20 minutes, then continue to add 4.2% fluorosilicone rubber and stir for 25 minutes. Then, divide the oil-based drilling fluid for plugging while drilling into two equal parts and add it to the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 2.

[0091] Example 7

[0092] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0093] The plugging agent includes modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20-100 meshes; the particle size of the mica flakes is 80-150 meshes; the particle size of the asbestos fibers is 55-80 meshes; and the particle size of the fluorosilicone rubber is 150-300 meshes.

[0094] The formula for preparing long-term temperature-resistant oil-based drilling fluid for plugging while drilling is: 400mL (350mL base oil + 50mL calcium chloride aqueous solution, where the calcium chloride concentration is 25%) + 3.5% primary emulsifier + 2.5% auxiliary emulsifier + 3.0% organic soil + 4.0% wetting agent + 3.5% oil-based filtrate reducer + 3.0% oil-based drilling fluid high temperature resistant plugging agent + 2.0% lime, and then use barite to increase the weight to 2.00g / cm 3 , add 12.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 4.8% mica flakes and stir for 10 minutes; continue to add 4.8% asbestos fiber and stir for 20 minutes, then continue to add 3.6% fluorosilicone rubber and stir for 25 minutes, then add it to the high temperature and high pressure sand bed filter loss instrument for experiment. The pressure-bearing plugging effect is shown in Table 2.

[0095] Example 8

[0096] This embodiment is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0097] The plugging agent includes modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, glass fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the glass fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0098] The formula for preparing long-term temperature-resistant oil-based drilling fluid for plugging while drilling is as follows: 800mL (640mL base oil + 160mL calcium chloride aqueous solution, where the calcium chloride concentration is 25%) + 3.5% primary emulsifier + 2.5% auxiliary emulsifier + 3.0% organic soil + 4.0% wetting agent + 3.5% oil-based fluid loss reducer + 3.0% oil-based drilling fluid high temperature resistant plugging agent + 2.0% lime, and then use barite to increase the weight to 2.00g / cm 3 , add 12.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 4.8% mica flakes and stir for 10 minutes; continue to add 4.8% glass fiber and stir for 20 minutes, then continue to add 3.6% fluorosilicone rubber and stir for 25 minutes. The oil-based drilling fluid for plugging while drilling is divided into two equal parts and added into the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 2.

[0099] Table 2 Pressure bearing capacity of different embodiments in oil-based drilling fluid for plugging while drilling

[0100]

[0101]

[0102] It can be seen from Table 2 that, under the condition of a temperature of 230°C, for the leakage caused by a quartz sand bed of 0.45 mm to 1.5 mm and a crack with a width of 0.5 mm or 1.0 mm, the long-acting temperature-resistant while-drilling plugging oil-based drilling fluid described in Examples 5-8 of the present invention has good pressure-bearing and plugging ability, and the pressure stabilization time reaches 7 days, which can achieve the purpose of long-term pressure-bearing and plugging the leaking layer.

[0103] Comparative Example 1

[0104] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0105] The plugging agent includes calcium carbonate, mica flakes, asbestos fiber and fluorosilicone rubber; the mass ratio of the calcium carbonate, mica flakes, asbestos fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the calcium carbonate is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the asbestos fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0106] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3, add 13.0% calcium carbonate through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss tester and the high-temperature and high-pressure micro-fracture plugging tester for experiments. The pressure plugging effect is shown in Table 3.

[0107] Comparative Example 2

[0108] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0109] The plugging agent includes diatomaceous earth, mica flakes, asbestos fiber and fluorosilicone rubber; the mass ratio of the diatomaceous earth, mica flakes, asbestos fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the diatomaceous earth is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the asbestos fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0110] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3 , add 13.0% diatomaceous earth through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss tester and the high-temperature and high-pressure micro-fracture plugging tester for experiments. The pressure plugging effect is shown in Table 3.

[0111] Comparative Example 3

[0112] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0113] The plugging agent includes coke particles, mica sheets, asbestos fibers and fluorosilicone rubber; the mass ratio of the coke particles, mica sheets, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the coke particles is 20 to 100 meshes; the particle size of the mica sheets is 80 to 150 meshes; the particle size of the asbestos fibers is 55 to 80 meshes; and the particle size of the fluorosilicone rubber is 150 to 300 meshes.

[0114] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3 , add 13.0% coke particles through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss tester and the high-temperature and high-pressure micro-fracture plugging tester for experiments. The pressure plugging effect is shown in Table 3.

[0115] Table 3 Pressure-bearing and plugging capabilities of different comparative examples in water-based drilling fluid

[0116]

[0117]

[0118] It can be seen from Table 3 that the plugging-while-drilling drilling fluids prepared using calcium carbonate, coke particles and diatomaceous earth as granular materials in Comparative Examples 1-3, respectively, have a short pressure-bearing time and a high leakage rate when dealing with permeability leakage and fine crack leakage at a high temperature of 230° C. and a pressure of 12.0 MPa, and have poor plugging effects, requiring repeated plugging construction.

[0119] Comparative Example 4

[0120] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0121] The plugging agent includes modified quartz sand, mica flakes, glass fiber and low-phenyl sulfide silica gel; the mass ratio of the modified quartz sand, mica flakes, glass fiber and low-phenyl sulfide silica gel is 10:4:4:3; wherein the particle size of the modified quartz sand is 20 mesh to 100 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the glass fiber is 55 mesh to 80 mesh; and the particle size of the low-phenyl sulfide silica gel is 150 mesh to 300 mesh.

[0122] Prepare the oil-based drilling fluid for plugging while drilling, the formula is: 1200mL (960mL base oil + 240mL calcium chloride aqueous solution, where the calcium chloride concentration is 25%) + 3.0% primary emulsifier + 2.0% auxiliary emulsifier + 3.5% organic soil + 2.0% wetting agent + 3.5% oil-based filtrate reducer + 4.0% oil-based drilling fluid high temperature resistant plugging agent + 2.0% lime, and then use barite to increase the weight to 1.50g / cm 3, add 14.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.6% mica flakes and stir for 10 minutes; continue to add 5.6% glass fiber and stir for 20 minutes, then continue to add 4.2% low-phenyl sulfide silica gel and stir for 25 minutes. The oil-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss instrument and the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 4.

[0123] Table 4 Pressure-bearing and plugging capabilities of different embodiments in oil-based drilling fluids

[0124]

[0125] It can be seen from Table 4 above that compared with Example 6, other materials in the plugging agent used in Comparative Example 4 are the same as those in Example 6, except that the elastic material is replaced by low-phenyl vulcanized silicone rubber from fluorosilicone rubber. Since low-phenyl vulcanized silicone has poor oil resistance and gradually dissolves under high temperature and high pressure, the pressure-bearing time for cracks with a width of 0.5 mm and 1.0 mm and a quartz sand bed of 0.45 mm to 1.5 mm under high temperature and high pressure is insufficient, and the time for sealing the holes is short.

[0126] Comparative Example 5

[0127] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0128] The plugging agent includes modified quartz sand, mica flakes, asbestos fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 150 mesh to 250 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the asbestos fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0129] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3 , add 13.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss instrument and the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 5.

[0130] Comparative Example 6

[0131] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0132] The plugging agent includes modified quartz sand, mica flakes, asbestos fiber and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fiber and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 250 mesh to 500 mesh; the particle size of the mica flakes is 80 mesh to 150 mesh; the particle size of the asbestos fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0133] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3 , add 13.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss instrument and the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 5.

[0134] Comparative Example 7

[0135] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0136] The plugging agent includes modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber; the mass ratio of the modified quartz sand, mica flakes, asbestos fibers and fluorosilicone rubber is 10:4:4:3; wherein the particle size of the modified quartz sand is 20-100 meshes; the particle size of the mica flakes is 80-150 meshes; the particle size of the asbestos fibers is 150-300 meshes; and the particle size of the fluorosilicone rubber is 150-300 meshes.

[0137] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 2.5% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 1.0% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 1.50g / cm 3, add 13.0% modified quartz sand through the feeding funnel and stir for 10 minutes; continue to add 5.2% mica flakes and stir for 10 minutes; continue to add 5.2% asbestos fiber and stir for 20 minutes, then continue to add 3.9% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss instrument and the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 5.

[0138] Table 5 Pressure-bearing and plugging capabilities of different comparative examples in water-based drilling fluid

[0139]

[0140] It can be seen from Table 5 above that when the particle size of the material in the plugging agent used for the long-term temperature-resistant while-drilling plugging drilling fluid changes, the prepared long-term temperature-resistant while-drilling plugging drilling fluid has obviously insufficient pressure-bearing capacity for 0.45mm-1.5mm quartz sand beds and cracks with widths of 0.5mm and 1.0mm, and the plugging effect is significantly reduced.

[0141] Comparative Example 8

[0142] This comparative example is used to illustrate the long-acting temperature-resistant while-drilling plugging drilling fluid and its preparation method of the present invention.

[0143] The plugging agent comprises quartz sand (unmodified), mica flakes, asbestos fiber and fluorosilicone rubber; the mass ratio of the quartz sand (unmodified), mica flakes, asbestos fiber and fluorosilicone rubber is 10:4:4:3;

[0144] Among them, the particle size of the quartz sand (unmodified) is 20 mesh to 100 mesh; the particle size of the mica sheet is 80 mesh to 150 mesh; the particle size of the asbestos fiber is 55 mesh to 80 mesh; and the particle size of the fluorosilicone rubber is 150 mesh to 300 mesh.

[0145] Prepare the water-based drilling fluid for plugging while drilling. The formula is: 1200mL water + 1.8% anti-salt soil + 0.2% sodium hydroxide + 5.0% sulfonated phenolic resin SMP-3 + 3.0% organic lignite fluid loss reducer + 3.5% sulfonated asphalt plugging agent + 0.8% benzene sulfonate copolymer fluid loss reducer DSP-2, and then add barite to increase the weight to 2.00g / cm 3 , add 12.0% quartz sand (unmodified) through the feeding funnel and stir for 10 minutes; continue to add 4.8% mica flakes and stir for 10 minutes; continue to add 4.8% asbestos fiber and stir for 20 minutes, then continue to add 3.6% fluorosilicone rubber and stir for 25 minutes. The water-based drilling fluid for plugging while drilling is divided into 3 equal parts and added to the high-temperature and high-pressure sand bed filter loss instrument and the high-temperature and high-pressure micro-fracture plugging instrument for experiments. The pressure plugging effect is shown in Table 6.

[0146] Table 6 Pressure bearing capacity of different embodiments in water-based drilling fluid for plugging while drilling

[0147]

[0148] It can be seen from Table 6 above that the quartz sand in the plugging agent used in the long-term temperature-resistant drilling plugging drilling fluid described in Comparative Example 8 is not modified, and can plug permeability leakage such as quartz sand beds with a particle size of 0.45mm to 1.5mm and cracks with a width of 0.5mm; however, for slightly larger crack-type leakage such as 1.0mm in width, it is not possible to perform long-term pressure-bearing plugging.

[0149] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A long-lasting temperature-resistant and leak-proof drilling fluid, comprising a base drilling fluid and a leak-proof agent, It is characterized in that The plugging agent comprises granular material, sheet material, fibrous material and elastic material; the mass ratio of the granular material, sheet material, fibrous material and elastic material is (10-14): (4-7): (4-6): (3-5); the elastic material is fluorosilicone rubber; the granular material is selected from quartz sand or modified quartz sand.

2. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to claim 1, It is characterized in that The particle size of the granular material is 20 mesh to 100 mesh; And / or, the preparation method of the modified quartz sand comprises sequentially performing physical modification and chemical modification on the quartz sand; preferably, the physical modification is shot peening; and the chemical modification is coating bisphenol A epoxy resin on the surface of the quartz sand by a thermal method.

3. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to claim 1 or 2, It is characterized in that The sheet material is a mica sheet; And / or, the particle size of the flaky material is 80 mesh to 150 mesh.

4. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to any one of claims 1 to 3, It is characterized in that The fibrous material is selected from at least one of glass fiber and asbestos fiber; And / or, the particle size of the fibrous material is 55 mesh to 80 mesh.

5. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to any one of claims 1 to 4, It is characterized in that The particle size of the elastic material is 150 meshes to 300 meshes.

6. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to any one of claims 1 to 5, It is characterized in that The basic drilling fluid is water-based drilling fluid and / or oil-based drilling fluid.

7. The long-lasting temperature-resistant plugging-while-drilling drilling fluid according to any one of claims 1 to 6, It is characterized in that Taking the volume of the long-acting temperature-resistant drilling-while-drilling plugging drilling fluid as 100%, the mass percentage of the plugging agent is 21% to 30%.

8. A method for preparing the long-acting temperature-resistant while-drilling plugging drilling fluid according to any one of claims 1 to 7, It is characterized in that The method comprises sequentially adding the granular material, the flaky material, the fibrous material and the elastic material into the basic drilling fluid.

9. Use of the long-acting temperature-resistant and leak-on-drilling plugging drilling fluid according to any one of claims 1 to 7 or the long-acting temperature-resistant and leak-on-drilling plugging drilling fluid prepared by the preparation method according to claim 8 in drilling.

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