Wall repairing liquid for oil-based drilling fluid as well as preparation method and application of wall repairing liquid

Abstract

The invention relates to the technical field of drilling engineering, and provides a wall repairing liquid for oil-based drilling fluid, which comprises the following components: 20-80 parts by weight of a cement consolidation agent; 40 to 100 parts by weight of a mineral admixture; 5-30 parts by weight of an activator; 10-50 parts by weight of an oil corrosion resistant agent; 0-100 parts by weight of a density regulator; 0-5 parts by weight of a flow pattern regulator; 0.1 to 20 parts by weight of a retarder; 0.1-20 parts by weight of a fluid loss agent; and 100 parts by weight of water. The repairing liquid has the advantages that the applicable temperature is 40-180 DEG C, the density is 1.2-2.1 g / cm < 3 >, the compatibility with an oil phase is good, the safety is high, the oil-based drilling fluid mixing resistance is high, a wall formed after curing is high in strength, high in oil corrosion resistance and high in long-term stability, the wall is prevented from being damaged and collapsed again, and the smooth drilling and completion construction is guaranteed. The invention further provides a preparation method and application of the repair liquid.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling engineering, and in particular relates to a sandwich wall repairing fluid for oil-based drilling fluid, a preparation method and application thereof. Background Art

[0002] With the deepening of exploration and development, shale gas and tight sandstone gas in new strata and new blocks have gradually become hot spots. Due to the scarcity of original geological data and the limited number of adjacent wells, the "straight pilot eye + horizontal well" mode is generally adopted for construction, that is, first drill a vertical well section to locate the producing layer, and at the same time evaluate more strata, and then backfill the cement plug according to the design requirements, and then side drill to increase the drilling rate of the horizontal section reservoir, so as to achieve the development goal of low cost and high return.

[0003] At present, oil-based drilling fluid is mainly used for drilling horizontal sections of shale formation wells. However, the cement slurry mixed with oil-based drilling fluid has poor consolidation effect and low strength of backfill cement plug, resulting in insufficient support capacity for drill bits during side drilling, causing the side drilling section to be too long and the formed sandwich wall to be long and thin (i.e., the intersection of the horizontal wellbore and the vertical wellbore, also known as the side drilling window). In addition, the strength of the cement plug is further reduced due to long-term corrosion by the oil-based drilling fluid, making it easy to drill into the straight pilot hole. Frequent movement of the drill bit and reaming to try to enter the horizontal wellbore cause the sandwich wall to collapse, resulting in the drill bit losing the support of the sandwich wall and being unable to enter the horizontal wellbore normally. The only option is to scrap the horizontal section, resulting in huge time and economic losses.

[0004] In view of the above problems, technicians in this field generally adopt two solutions: filling well side drilling to find horizontal wellbore and consolidation type material to repair sandwich wall. Filling well side drilling to find horizontal wellbore: Due to the problems of wellbore trajectory control, "zero length" of inclinometer, data accuracy, three-dimensional trajectory, platform well collision prevention, etc., the side drilling technology for finding horizontal wellbore is not mature yet, and there are few successful cases reported in China, especially in the horizontal well section with a burial depth of 2000-4000m, which is difficult to complete with the existing technology level. The consolidation material on site is generally cement slurry, which mainly uses the principle of cement gelation and solidification to achieve the purpose of repairing the sandwich wall and provide a certain support force for the drill to enter the horizontal wellbore normally. However, there are the following problems: (1) The consolidation effect of cement mixed with oil-based drilling fluid is poor: the compatibility of cement slurry and oil-based drilling fluid is poor. The oil phase without consolidation plays a role of wrapping, isolation and lubrication between cement particles, which hinders the full hydration of cement, greatly reduces the consolidation strength, and even makes it difficult to consolidate; (2) The sandwich wall formed after cement slurry solidification has poor oil corrosion resistance and insufficient long-term stability: the cement solidified body (hereinafter referred to as cement stone) ) Under the long-term penetration, corrosion and scouring of oil-based drilling fluid, the oil phase gradually penetrates into the structure of cement stone, destroying the bonding force between cement stone, thus reducing its strength, even becoming loose and structurally damaged; (3) Low displacement efficiency and excessive mixing of slurry at large boreholes with irregular diameters: a. Damage to the sandwich wall causes the horizontal wellbore and the vertical wellbore to be connected, forming an irregular big-bellied wellbore. The annular return velocity at the large borehole is low, the displacement efficiency is poor, and a large amount of oil-based drilling fluid, cement stone and empty mud cake remain. The cement slurry loses its consolidation ability after being mixed with excessive oil-based drilling fluid; b. The adjustable range of cement slurry density is 1.8-1.9 g / cm 3 The density of oil-based drilling fluid is generally 1.2 to 2.1 g / cm2 depending on the formation pressure. 3 There is a density difference between the two, and the gravity replacement effect during displacement and post-setting further aggravates the mixing volume.

[0005] A Chinese patent with publication number CN113845890A discloses a well wall repair agent suitable for broken formations. The well wall repair agent uses a well wall repair agent with strong adhesion, high elastic toughness and high temperature resistance. The ingredients include ultrafine cement, elastic epoxy resin, epoxy resin emulsifier, latent curing agent, nanomaterials, etc. It is mainly used for well wall repair in high-temperature deep well dolomite and carbonate rock broken formations, but its applicable temperature is 140-170°C, which is not suitable for medium and shallow well mudstone, sandstone, shale formations (40-140°C), and the consolidation strength of the well wall repair agent after mixing with oil-based drilling fluid is difficult to achieve the effect of repairing sandwich walls.

[0006] A Chinese patent with publication number CN103387825A discloses a branch well sandwich wall curing liquid and a preparation method thereof. The curing liquid provided includes modified epoxy furan, an organic amine curing agent, a diluent and other ingredients. The main purpose is to use chemical curing technology in advance to improve the rock strength of the sandwich wall of a branch well in a loose sandstone formation when the sandwich wall is not damaged, thereby improving its stability. However, it is not suitable for repair operations after the sandwich wall is damaged. Summary of the invention

[0007] In view of this, the present invention provides a sandwich wall repair fluid for oil-based drilling fluid, a preparation method and application thereof. The repair fluid has strong oil resistance and a wide application range of density and temperature, and can be applied to sandwich wall repair operations of oil-based drilling fluid wells in different blocks and formations. The sandwich wall repair method improves the displacement efficiency of irregular wellbores with large well diameters by improving the drill tool structure and optimizing the construction process without increasing the cost. The sandwich wall repair method has high on-site reproducibility, strong operability and significant application effect. The sandwich wall formed by the method provided by the present invention has high strength, strong oil erosion resistance and high long-term stability, and will not be damaged or collapsed again, thereby ensuring smooth drilling and completion construction.

[0008] The present invention provides a sandwich wall repairing fluid for oil-based drilling fluid, comprising:

[0009]

[0010] The activator is selected from one or more of sodium carbonate, calcium chloride, calcium oxide and sodium sulfate;

[0011] The oil corrosion resistant agent is selected from one or more of modified pumice powder, microsilica powder and inorganic salt water purifier.

[0012] Preferably, the oil corrosion resistant agent is selected from modified pumice powder, microsilica powder and inorganic salt water purifier; the mass ratio of the modified pumice powder, microsilica powder and inorganic salt water purifier is (50-100): (20-45): (10-25).

[0013] Preferably, the mass percentage of the modified pumice powder in the oil corrosion resistant agent is greater than or equal to 55%.

[0014] Preferably, the modified pumice powder is calcined pumice powder modified by a silane coupling agent.

[0015] Preferably, the modified pumice powder is prepared according to the following method:

[0016] A1) mixing pumice powder with an alkaline substance, calcining and activating the mixture, to obtain calcined pumice powder;

[0017] A2) Under stirring conditions, a silane coupling agent solution is sprayed onto the calcined pumice powder at room temperature by atomization, and after drying, a modified pumice powder is obtained.

[0018] Preferably, the mass ratio of the pumice powder to the alkaline substance is 1:(0.015-0.035); the calcination activation temperature is 300-550°C; the calcination activation time is 3-5h;

[0019] The silane coupling agent solution is a solution of silane coupling agent and ethanol; the mass ratio of the silane coupling agent to ethanol is (0.4-0.6):1; the mass of the silane coupling agent solution is 0.5%-1.5% of the mass of the calcined pumice powder.

[0020] Preferably, the inorganic salt water purifier is selected from ferric chloride and potassium aluminum sulfate dodecahydrate; the mass ratio of ferric chloride to potassium aluminum sulfate dodecahydrate is (10-20): (0-1).

[0021] Preferably, the cement-based solidifying agent is selected from one or more of aluminate cement, ordinary cement, ultrafine cement and oil well G grade cement;

[0022] The mineral admixture is selected from one or more of ultra-fine blast furnace slag, tuff powder, zeolite powder, fly ash and burnt shale powder;

[0023] The density regulator is selected from a weighting agent or a lightening agent; the weighting agent is selected from one or more of barite, hematite and ilmenite; the lightening agent is selected from one or more of perlite beads, hollow glass microspheres and urea-formaldehyde resin microspheres;

[0024] The flow pattern regulator is selected from one or more of sulfonated aldehyde-ketone condensates, hydroxycarboxylic acid compounds and hydroxypolysaccharide compounds;

[0025] The retarder is selected from one or more of lignin sulfonate retarders, hydroxycarboxylate retarders, cellulose derivative retarders, AMPS polymer retarders and inorganic-organic polymer oil well cement retarders;

[0026] The fluid loss reducer is selected from one or more of hydroxycarboxylic acid fluid loss reducers, inorganic compound fluid loss reducers, cellulose derivative fluid loss reducers, AMPS multipolymer fluid loss reducers and inorganic non-metal-organic polymer fluid loss reducers.

[0027] The present invention also provides a method for preparing the above-mentioned sandwich wall repairing fluid for oil-based drilling fluid, comprising the following steps:

[0028] S1) mixing water, flow pattern regulator, retarder and fluid loss reducer uniformly to obtain slurry preparation water;

[0029] S2) mixing the slurry preparation water, cement-based solidifying agent, mineral admixture, activator, oil-resistant corrosion agent and density regulator evenly to obtain a sandwich wall repair fluid for oil-based drilling fluid.

[0030] The present invention also provides a method for repairing a sandwich wall, comprising the following steps:

[0031] B1) Clean the well wall and wellbore;

[0032] B2) Pump the oil-based drilling fluid into the well with the sandwich wall repair fluid, and then use the drilling fluid to replace the repair fluid. When the repair fluid comes out of the drill bit, adjust the position of the drill bit so that the bottom jet tool is at the damaged part of the sandwich wall, and move the drill bit up and down, and dynamically pump the repair fluid until the inside and outside of the drill bit are balanced;

[0033] B3) Drilling to above the level of repair fluid;

[0034] B4) Circulate and drain the mixed slurry;

[0035] B5) Wait for condensation.

[0036] The invention provides a sandwich wall repairing fluid for oil-based drilling fluid, comprising: 20-80 parts by weight of a cement-based solidifying agent; 40-100 parts by weight of a mineral admixture; 5-30 parts by weight of an activator; 10-50 parts by weight of an oil-resistant corrosion agent; 0-100 parts by weight of a density regulator; 0-5 parts by weight of a flow pattern regulator; 0.1-20 parts by weight of a retarder; 0.1-20 parts by weight of a fluid loss reducing agent; and 100 parts by weight of water; the oil-resistant corrosion agent comprises modified pumice powder, microsilica powder and an inorganic salt water purifier; the mass ratio of the modified pumice powder, microsilica powder and the inorganic salt water purifier is (50-100): (20-45): (10-25), and the mass percentage of the modified pumice powder in the oil-resistant corrosion agent is greater than or equal to 55%. Compared with the prior art, the sandwich wall repair fluid for oil-based drilling fluid provided by the present invention, its preparation method and application can effectively solve the problems of non-consolidation of cement slurry mixed with oil-based drilling fluid and low displacement efficiency in irregular wellbore with large diameter, and provide a reliable technical measure for solving the sandwich wall repair of oil-based drilling fluid in large-bellied wellbore. The synergistic effect of multiple components in the oil-resistant corrosion agent not only enhances the consolidation ability of the repair fluid in the oil-based drilling fluid environment, but also improves the oil corrosion resistance, so that the sandwich wall can stably provide a certain support force for the drill tool for a long time, ensuring the smooth progress of subsequent construction operations; and the solid formed after the repair fluid is solidified The structure has high strength and lasting oil corrosion resistance, and there will be no problem of a significant decrease in strength or even damage due to long-term scouring and corrosion of oil-based drilling fluid. In addition, the repair fluid has good stability and is suitable for both low-temperature and medium-high-temperature formations. It has a wide adjustable density range and high safety. It can be used in oil-based drilling fluid wells in different blocks and formations to solve the complex problem of the inability of the drill bit to enter the horizontal wellbore after the sandwich wall is damaged, resulting in the scrapping of the footage. At the same time, the strong oil corrosion resistance can ensure that the sandwich wall will not be damaged or collapsed again, causing serious accidents such as drill sticking and the scrapping of the wellbore due to the failure of the casing to be put in place, thereby ensuring the smooth progress of drilling and completion construction.

[0037] The experimental results show that the oil-based drilling fluid provided by the present invention has a wide range of applications, and is suitable for temperatures of 40 to 180°C and densities of 1.2 to 2.1 g / cm 3 The thickening time is adjustable from 180 to 550 minutes. It can be used for the repair of sandwich walls in different blocks, formation lithology and pressure coefficients. It has good compatibility when in contact with oil-based drilling fluid, and no adverse phenomena such as severe heat release and flash condensation occur. The construction safety is high. The sandwich wall formed by mixing with oil-based drilling fluid (<35%) has high strength and can meet the repair of sandwich walls in most oil-based drilling fluid wells. In addition, the repair fluid exhibits good consolidation and oil corrosion resistance. The compressive strength of the consolidated body is greater than 10MPa, the compressive strength of the mixed 35% oil-based drilling fluid is above 5.5MPa, and the compressive strength of the oil-immersed 30D is The increase is 10% and the oil phase immersion depth ratio is less than 10%, which solves the problems of non-solidification and oil corrosion resistance of the original mixed oil-based drilling fluid, and effectively improves the long-term stability of the sandwich wall after the oil-based drilling fluid repair; furthermore, the application method of the repair fluid, by improving the drill tool structure and optimizing the construction process without increasing the cost, can effectively clean the residual cement stone, virtual mud cake, and oil-based drilling fluid in the big belly wellbore after the sandwich wall is damaged, greatly improves the displacement efficiency, and reduces the mixing degree of the repair fluid and the oil-based drilling fluid. It has high on-site reproducibility, strong operability, and significant application effect. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] The present invention provides a sandwich wall repairing fluid for oil-based drilling fluid, comprising:

[0040]

[0041] The activator is one or more of sodium carbonate, calcium chloride, calcium oxide and sodium sulfate;

[0042] The oil-resistant corrosion agent is one or more of modified pumice powder, microsilica powder and inorganic salt water purifier.

[0043] The repair fluid provided by the present invention has good compatibility with the oil phase and high safety. The sandwich wall formed by the mixed oil-based drilling fluid (<35%) has high strength and strong oil corrosion resistance, and will not be damaged or collapsed again, thereby ensuring smooth drilling and completion construction.

[0044] Among them, the content of the cement-based consolidating agent in the sandwich wall repair fluid for oil-based drilling fluid is preferably 30 to 80 parts by weight, and more preferably 40 to 80 parts by weight; in the embodiments provided by the present invention, the content of the cement-based consolidating agent in the sandwich wall repair fluid for oil-based drilling fluid is specifically 50 parts by weight, 40 parts by weight, 60 parts by weight or 80 parts by weight; the cement-based consolidating agent is preferably one or more of aluminate cement, ordinary cement, ultrafine cement and oil well G-grade cement, and more preferably ultrafine cement and / or oil well G-grade cement.

[0045] The content of the mineral admixture in the cladding wall repairing fluid for oil-based drilling fluid is preferably 55 to 100 parts by weight; in the embodiment provided by the present invention, the content of the mineral admixture in the cladding wall repairing fluid for oil-based drilling fluid is specifically 60 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight or 50 parts by weight; the mineral admixture is preferably one or more of ultrafine blast furnace slag, tuff powder, zeolite powder, fly ash and burnt shale powder; the particle size D of the ultrafine blast furnace slag is 90 Preferably, the particle size D of the tuff powder, zeolite powder, fly ash and burnt shale powder is less than or equal to 100 μm, more preferably less than or equal to 50 μm, more preferably less than or equal to 30 μm, and most preferably less than or equal to 10 μm. 90 Each independently is preferably equal to or less than 150 μm, more preferably equal to or less than 100 μm, further preferably equal to or less than 70 μm, and most preferably equal to or less than 50 μm.

[0046] The content of the activator in the sandwich wall repair fluid for oil-based drilling fluid is preferably 10 to 30 parts by weight, and more preferably 10 to 25 parts by weight; in the embodiments provided by the present invention, the content of the activator in the sandwich wall repair fluid for oil-based drilling fluid is specifically 10 parts by weight, 15 parts by weight, 20 parts by weight or 25 parts by weight; the activator is preferably one or more of sodium carbonate, calcium chloride, calcium oxide and sodium sulfate, and more preferably one or more of sodium carbonate, sodium sulfate and calcium oxide.

[0047] The content of the oil-resistant corrosion agent in the sandwich wall repair fluid for oil-based drilling fluid is preferably 15 to 46 parts by weight, and more preferably 22.6 to 45.3 parts by weight; in the embodiment provided by the present invention, the content of the oil-resistant corrosion agent in the sandwich wall repair fluid for oil-based drilling fluid is specifically 5 parts by weight, 15 parts by weight, 22.6 parts by weight, 2.65 parts by weight or 45.3 parts by weight; the oil-resistant corrosion agent is preferably one or more of modified pumice powder, microsilica powder and inorganic salt water purifier, and more preferably modified pumice powder, microsilica powder and inorganic salt water purifier; further preferably, the mass percentage of the modified pumice powder in the oil-resistant corrosion agent is greater than or equal to 55%; the mass ratio of the modified pumice powder, microsilica powder and inorganic salt water purifier is preferably (50 to 100 ): (20-45): (10-25), more preferably (50-90): (20-40): (10-20), and more preferably (50-75): (20-35): (10-15); in some embodiments provided by the present invention, the mass ratio of the modified pumice powder, microsilica powder and inorganic salt water purifier is specifically 75:25:13 or 50:30:10.6; the modified pumice powder is preferably calcined pumice powder modified by a silane coupling agent, and more preferably alkaline pumice powder modified by a silane coupling agent; in the present invention, the modified pumice powder is preferably prepared according to the following method: A1) mixing pumice powder with an alkaline substance, calcining and activating, to obtain calcined pumice powder; A2) mixing silane coupling agent with water under stirring The agent solution is sprayed onto the calcined pumice powder by atomization at room temperature, and after drying, the modified pumice powder is obtained; the particle size of the pumice powder is preferably 800 mesh, more preferably 600 mesh, more preferably 400 mesh, and most preferably 325 mesh; the alkaline substance is an alkaline substance well known to those skilled in the art, and there is no special restriction. In the present invention, it is preferably a hydroxide and a carbonate; the hydroxide is preferably an alkali metal hydroxide, more preferably sodium hydroxide and / or potassium hydroxide; the carbonate is preferably an alkali metal carbonate and / or an alkaline earth metal carbonate, more preferably one or more of sodium carbonate, potassium carbonate and calcium carbonate; the mass ratio of the hydroxide to the carbonate is preferably (55-75): (30-50); the mass ratio of the pumice powder to the alkaline substance is preferably (55-75): (30-50); The ratio of 1:(0.015-0.035) is 1:(0.015-0.035); the calcination activation temperature is preferably 300-550°C; the calcination activation time is preferably 3-5h; the stirring speed is preferably 800-1500r / min, more preferably 1000-1500r / min, and more preferably 1200r / min; the silane coupling agent solution is preferably a solution of silane coupling agent and ethanol; the mass ratio of the silane coupling agent to ethanol is preferably (0.4-0.6):1; the silane coupling agent can be a silane coupling agent well known to those skilled in the art, and there is no special limitation. In the present invention, the silane coupling agent KH-502 is preferably used; the mass of the silane coupling agent solution is preferably 0.5%-1.5%; after drying, it is preferably dispersed by high-speed stirring to obtain modified pumice powder; the microsilica powder is preferably silicon dioxide powder with a purity greater than 98%; the particle size of the microsilica powder is preferably 0.1-0.3 μm; the inorganic salt water purifier is preferably ferric chloride and potassium aluminum sulfate dodecahydrate; the mass ratio of ferric chloride to potassium aluminum sulfate dodecahydrate is preferably (10-20):(0-1), more preferably (10-18):(0.3-1), more preferably (10-15):(0.5-0.8), and most preferably (10-15):0.6. In the present invention, the mechanism of action of the oil-resistant corrosion agent is as follows: ① High-temperature calcination causes the organic matter in the micropores and voids of the pumice powder to volatilize, the pores are unblocked, and the specific surface area and adsorption capacity are higher. The silane coupling agent solution treatment improves the lipophilicity of the porous structure, improves the compatibility and dispersibility in the process of adsorption and absorption of the oil phase, and helps to adsorb the oil phase in the repair liquid in the porous microstructure, reducing the possibility of the oil phase wrapping the consolidating agent particles to hinder the hydration reaction, and greatly improves the reaction activity of the consolidating agent after mixing the oil phase; ② Micron-grade silicon powder can effectively fill the micropores between the repair liquid particles and improve the compactness; ③ Anhydrous ferric chloride and potassium aluminum sulfate dodecahydrate can consume the negative products generated by the consolidation reaction, make the consolidation structure uniform, and improve the ability to resist oil phase penetration. Through the synergistic effect and mutual cooperation of multiple components of the oil-resistant corrosion agent, the oil corrosion resistance and long-term stability of the sandwich wall formed by the consolidation of the repair liquid are improved. .

[0048] The density regulator can be added according to the density of the oil-based drilling fluid for the sandwich wall repair fluid required by different blocks, formation lithology and pressure coefficient; the density regulator is preferably a weighting agent or a lightening agent; the weighting agent is preferably one or more of barite, hematite and ilmenite; the lightening agent is preferably one or more of perlite beads, hollow glass microspheres and urea-formaldehyde resin microspheres. By adding the density regulator, the adjustment range of the repair fluid density can be broadened, overcoming the problem of more slurry mixing when contacting with the drilling fluid due to the narrow adjustable range of cement slurry density.

[0049] The content of the flow pattern regulator in the sandwich wall repair fluid for oil-based drilling fluid is preferably 0 to 3 parts by weight, more preferably 0 to 2 parts by weight, and even more preferably 1 to 2 parts by weight; the flow pattern regulator is preferably one or more of sulfonated aldehyde ketone condensates, hydroxycarboxylic acid compounds and hydroxy polysaccharide compounds.

[0050] The content of the retarder in the sandwich wall repair fluid for oil-based drilling fluid is preferably 0-15 parts by weight, more preferably 0-10 parts by weight, and even more preferably 1-5 parts by weight; in the embodiments provided by the present invention, the content of the retarder in the sandwich wall repair fluid for oil-based drilling fluid is specifically 0 parts by weight, 1 part by weight, 2 parts by weight, 3.5 parts by weight, 4 parts by weight or 5 parts by weight; the retarder can be a retarder well known to those skilled in the art without any special limitation, and in the present invention, it is preferably one or more of lignin sulfonate retarder, hydroxycarboxylate retarder, cellulose derivative retarder, AMPS polymer retarder and inorganic-organic polymer oil well cement retarder, and more preferably AMPS polymer retarder high temperature retarder ZYH or high temperature oil well cement retarder ZRT-1.

[0051] The content of the fluid loss agent in the sandwich wall repair fluid for oil-based drilling fluid is preferably 0.5-20 parts by weight, more preferably 1-15 parts by weight, and even more preferably 2-11 parts by weight; in the embodiments provided by the present invention, the content of the fluid loss agent in the sandwich wall repair fluid for oil-based drilling fluid is specifically 2 parts by weight, 4 parts by weight, 4.5 parts by weight, 6 parts by weight or 11 parts by weight; the fluid loss agent can be a fluid loss agent well known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably one or more of hydroxycarboxylic acid fluid loss agents, inorganic compound fluid loss agents, cellulose derivative fluid loss agents, AMPS multipolymer fluid loss agents and inorganic non-metal-organic polymer fluid loss agents, and more preferably AMPS multipolymer high temperature fluid loss agent ZYJ and / or inorganic non-metal-organic polymer high temperature oil well cement fluid loss agent ZFA-1.

[0052] The density of the sandwich wall repair fluid for oil-based drilling fluid provided by the present invention is preferably 1.2 to 2.1 g / cm 3 .

[0053] The sandwich wall repairing fluid for oil-based drilling fluid provided by the present invention can be suitable for 40-180° C. by adjusting the content of each component.

[0054] The sandwich wall repair fluid for oil-based drilling fluid and the application method provided by the present invention can effectively solve the problems of non-consolidation of cement slurry mixed with oil-based drilling fluid and low displacement efficiency at large-diameter irregular wellbores, and provide a reliable technical measure for solving the sandwich wall repair of large-bellied wellbores with oil-based drilling fluids. The synergistic effect of multiple components in the oil-resistant corrosion agent not only enhances the consolidation ability of the repair fluid in the oil-based drilling fluid environment, but also improves the oil corrosion resistance, so that the sandwich wall can provide a certain support force to the drill tool for a long time and stably, ensuring the smooth progress of subsequent construction operations; and the solidified body formed after the repair fluid is solidified has high strength and The oil corrosion resistance is long-lasting, and there will be no problem of a significant decrease in strength or even damage due to long-term scouring and corrosion of oil-based drilling fluid. Furthermore, the repair fluid has good stability and is suitable for both low-temperature and medium-high-temperature formations. It has a wide adjustable density range and high safety. It can be used in oil-based drilling fluid wells in different blocks and formations to solve the complex problem of the inability of the drill bit to enter the horizontal wellbore after the sandwich wall is damaged, resulting in the scrapping of the footage. At the same time, the strong oil corrosion resistance can ensure that the sandwich wall will not be damaged or collapsed again, causing serious accidents such as drill sticking and the scrapping of the wellbore due to the failure of the casing to be put in place, thereby ensuring the smooth progress of drilling and completion construction.

[0055] The present invention also provides a method for preparing the above-mentioned sandwich wall repair fluid for oil-based drilling fluid, comprising the following steps: S1) uniformly mixing water, a flow pattern regulator, a retarder and a fluid loss reducer to obtain slurry preparation water; S2) uniformly mixing the slurry preparation water, a cement-based solidifying agent, a mineral admixture, an activator, an oil-resistant corrosion agent and a density regulator to obtain the sandwich wall repair fluid for oil-based drilling fluid.

[0056] The present invention has no particular limitation on the sources of all raw materials, and any raw materials available on the market can be used.

[0057] The present invention also provides a method for repairing a sandwich wall, comprising the following steps: B1) cleaning the well wall and the wellbore; B2) pumping a repair fluid into the well, and then using drilling fluid to replace the repair fluid, after the repair fluid comes out of the drill tool, adjusting the position of the drill tool so that the bottom jet tool is at the damaged part of the sandwich wall, and moving the drill tool up and down, and dynamically pumping the repair fluid until the inside and outside of the drill tool are balanced; B3) pulling the drill to above the liquid level of the repair fluid; B4) circulating and draining the slurry; B5) waiting for solidification.

[0058] The repair method provided by the present invention can effectively clean up the cement stone, empty mud cake and oil-based drilling fluid remaining in the big-bellied wellbore after the sandwich wall is damaged. Under the premise of not increasing the cost, by improving the drill tool structure and optimizing the construction process, relying on the high-speed injection and flushing effect of the jet tool, the displacement efficiency of the large-diameter part of the irregular wellbore is greatly improved, and the mixing degree of the repair fluid and the drilling fluid is reduced. The method is suitable for the sandwich wall repair operations of branch wells, side drilling wells and pilot horizontal wells such as water-based drilling fluid and oil-based drilling fluid wells. Cement slurry or the repair fluid and preparation method proposed by the present invention can be used in the water-based drilling fluid, but the repair fluid and preparation method proposed by the present invention must be used in the oil-based drilling fluid well to achieve good results.

[0059] First, the wellbore and the wellbore are cleaned; the improved drill tool structure described in the present invention is specifically that the bottom of the bare drill rod is connected to a jet tool; the optimized construction process is specifically that the bare drill rod with the jet tool connected to the bottom is lowered to below the damaged part of the sandwich wall to clean the wellbore and the wellbore; the jet tool is preferably a bypass valve or a rotary jet auxiliary tool, and is more preferably a bypass valve; in the present invention, it is preferred to lower the bare drill rod with the jet tool connected to the bottom to 5 to 15 meters below the damaged part of the sandwich wall, and is more preferably 10 meters; the wellbore and the wellbore are cleaned preferably by large-volume circulating flushing, and more preferably by simultaneously moving the drill tool up and down significantly to destroy the cement stone and the virtual mud cake adhered to the wellbore wall to clean the wellbore.

[0060] Then, it is preferred to open the side channel of the bottom jet tool, pump the repair fluid into the well, and then use the drilling fluid to replace the repair fluid. After the repair fluid comes out of the drill tool, adjust the position of the drill tool so that the bottom jet tool is at the damaged part of the sandwich wall, and move the drill tool up and down to dynamically pump the repair fluid until the inside and outside of the drill tool are balanced. In the present invention, it is preferred to first adjust the formula of the repair fluid according to the formation temperature, drilling fluid performance, wellbore conditions, etc., so that its density is consistent with that of the drilling fluid, and then pump it into the well; when the repair fluid comes out of the drill tool for 3 to 5 m, 3 Finally, adjust the position of the drilling tool so that the bottom jet tool reaches the damaged part of the sandwich wall; the range of the drilling tool activity is preferably 10m above and below the damaged part of the sandwich wall.

[0061] After the repair fluid is dynamically pumped to balance the inside and outside of the drill bit, the drill is preferably pulled out to above the repair fluid level, more preferably 200 to 400 m above the repair fluid level, and more preferably 300 m above the repair fluid level to circulate and drain the slurry.

[0062] Finally, the repair of the sandwich wall can be completed by waiting for setting; the waiting time for setting is preferably 40 to 72 hours.

[0063] In order to further illustrate the present invention, the following describes in detail the sandwich wall repairing fluid for oil-based drilling fluid, the preparation method and application thereof in combination with the embodiments.

[0064] The reagents used in the following examples are all commercially available. Oil well G-grade cement and ultrafine cement were purchased from Sichuan Jiahua Enterprise (Group) Co., Ltd.; fly ash and ultrafine blast furnace slag were purchased from Shandong Kangjing New Materials Technology Co., Ltd.; perlite beads, microsilica powder (0.1-0.3 μm), and zeolite powder were purchased from Lingshou County Qiangdong Mineral Products Processing Plant; sulfonated aldehyde ketone condensate USZ was purchased from Weihui Chemical Co., Ltd.; medium and high temperature retarder ZYH, high temperature oil well cement retarder ZRT-1 and retarder ZYH-1, and modified pumice powder can be provided by the Drilling Engineering Technology Research Institute of Sinopec Zhongyuan Petroleum Engineering Co., Ltd. The medium and high temperature retarder ZYH can be prepared according to the method of Example 1 provided in Chinese patent CN109503760B. The modified pumice powder is calcined pumice powder modified by a silane coupling agent, and the preparation method is as follows: a) taking a certain amount of pumice, crushing and grinding it, and passing it through a 325-mesh sieve to obtain pumice powder; stirring and mixing the pumice powder and alkaline substance (sodium hydroxide: calcium carbonate=60:40) in a mass ratio of 1:0.025, and activating at 450°C for 4 hours to obtain calcined pumice powder; b) adding the calcined pumice powder obtained in step a) into a high-speed mixer, stirring at a high speed of 1200r / min, and at the same time, spraying a silane coupling agent (KH-502) solution (a solution in which the mass ratio of the silane coupling agent to ethanol is 0.5:1) uniformly atomized onto the powder through a spray device, wherein the mass ratio of the silane coupling agent solution to the calcined pumice powder is 1%, heating and drying are performed to volatilize the solvent, and finally stirring at a high speed to break it up and collect the sample to obtain the modified pumice powder.

[0065] Example 1

[0066] Step 1) Preparation of slurry water: 100 parts of water and 2 parts of fluid loss reducer ZYJ are mixed evenly by weight to obtain slurry water.

[0067] Step 2) Preparation of repair fluid: Add 50 parts of consolidating agent oil well G grade cement, 60 parts of mineral admixture fly ash, 10 parts of activator calcium oxide, 5 parts of oil corrosion resistant agent microsilica powder, and 20 parts of density regulator perlite beads to the slurry water in step 1), mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0068] Example 2

[0069] Step 1) Preparation of slurry water: by weight, 100 parts of water, 1 part of retarder ZYH, and 4 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0070] Step 2) Preparation of repair liquid: Add 50 parts of consolidating agent ultrafine cement, 80 parts of mineral admixture ultrafine blast furnace slag, 10 parts of activator sodium sulfate, and 15 parts of oil-resistant corrosion-resistant modified pumice powder to the slurry water in step 1), mix well, measure the density of the repair liquid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0071] Example 3

[0072] Step 1) Preparation of slurry water: by weight, 100 parts of water, 2 parts of retarder ZYH, and 4.5 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0073] Step 2) Preparation of repair fluid: In the slurry water in step 1), add 40 parts of consolidating agent oil well G grade cement, 70 parts of mineral admixture ultrafine blast furnace slag, 20 parts of mineral admixture fly ash, 15 parts of activator sodium carbonate, 15 parts of oil corrosion resistant modified pumice powder, 5 parts of oil corrosion resistant microsilica powder, 2.5 parts of oil corrosion resistant anhydrous ferric chloride, 0.1 parts of oil corrosion resistant potassium aluminum sulfate dodecahydrate, mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0074] Example 4

[0075] Step 1) Preparation of slurry water: by weight, 100 parts of water, 3.5 parts of retarder ZRT-1, and 2 parts of fluid loss reducer ZYA-1 are mixed uniformly to obtain slurry water.

[0076] Step 2) Preparation of repair liquid: Add 60 parts of consolidating agent ultrafine cement, 90 parts of mineral admixture zeolite powder, 15 parts of activator calcium oxide, 2.5 parts of oil corrosion resistant anhydrous ferric chloride, 0.15 parts of oil corrosion resistant potassium aluminum sulfate dodecahydrate, and 10 parts of density regulator barite to the slurry water in step 1), mix well, measure the density of the repair liquid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0077] Example 5

[0078] Step 1) Preparation of slurry water: by weight, 100 parts of water, 4 parts of retarder ZRT-1, 6 parts of fluid loss reducer ZFA-1, and 1 part of flow pattern regulator sulfonated aldehyde ketone condensate USZ are mixed evenly to obtain slurry water.

[0079] Step 2) Preparation of repair fluid: Add 40 parts of consolidating agent oil well G grade cement, 100 parts of mineral admixture ultrafine blast furnace slag, 20 parts of activator calcium oxide, and 50 parts of density regulator barite to the slurry water in step 1, mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0080] Example 6

[0081] Step 1) Preparation of slurry water: by weight, 100 parts of water, 5 parts of retarder ZRT-1, 11 parts of fluid loss reducer ZFA-1, and 2 parts of flow pattern regulator sulfonated aldehyde ketone condensate USZ are mixed evenly to obtain slurry water.

[0082] Step 2) Preparation of repair fluid: Add 80 parts of consolidating agent oil well G grade cement, 20 parts of mineral admixture fly ash, 30 parts of mineral admixture zeolite powder, 25 parts of activator calcium oxide, 25 parts of modified pumice powder, 15 parts of microsilica powder, 5 parts of anhydrous ferric chloride, 0.3 parts of oil corrosion resistant agent potassium aluminum sulfate dodecahydrate, and 90 parts of density regulator barite to the slurry water in step 1, mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0083] Comparative Example 1

[0084] To prepare ordinary cement slurry, mix 100g of water with 230g of cement, mix evenly, measure the density and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0085] Comparative Example 2

[0086] Step 1) Preparation of slurry water: by weight, 100 parts of water, 2 parts of retarder ZYH, and 4.5 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0087] Step 2) Preparation of repair fluid: Add 40 parts of consolidating agent oil well G grade cement, 70 parts of mineral admixture ultrafine blast furnace slag, 20 parts of mineral admixture fly ash, 15 parts of activator sodium carbonate, and 15 parts of oil corrosion resistant modified pumice powder to the slurry water in step 1), mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0088] Comparative Example 3

[0089] Step 1) Preparation of slurry water: by weight, 100 parts of water, 2 parts of retarder ZYH, and 4.5 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0090] Step 2) Preparation of repair fluid: Add 40 parts of consolidating agent oil well G grade cement, 70 parts of mineral admixture ultrafine blast furnace slag, 20 parts of mineral admixture fly ash, 15 parts of activator sodium carbonate, 5 parts of oil corrosion resistant agent microsilica powder to the slurry water in step 1), mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0091] Comparative Example 4

[0092] Step 1) Preparation of slurry water: by weight, 100 parts of water, 2 parts of retarder ZYH, and 4.5 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0093] Step 2) Preparation of repair fluid: Add 40 parts of consolidating agent oil well G grade cement, 70 parts of mineral admixture ultrafine blast furnace slag, 20 parts of mineral admixture fly ash, 15 parts of activator sodium carbonate, 2.5 parts of oil corrosion resistant anhydrous ferric chloride, and 0.1 parts of oil corrosion resistant potassium aluminum sulfate dodecahydrate to the slurry water in step 1), mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0094] Comparative Example 5

[0095] Step 1) Preparation of slurry water: by weight, 100 parts of water, 2 parts of retarder ZYH, and 4.5 parts of fluid loss reducer ZYJ are mixed evenly to obtain slurry water.

[0096] Step 2) Preparation of repair fluid: In the slurry water in step 1), add 40 parts of consolidating agent oil well G grade cement, 70 parts of mineral admixture ultrafine blast furnace slag, 20 parts of mineral admixture fly ash, 15 parts of activator sodium carbonate, 10 parts of oil corrosion resistant modified pumice powder, 10 parts of oil corrosion resistant microsilica powder, 2.5 parts of oil corrosion resistant anhydrous ferric chloride, 0.1 parts of oil corrosion resistant potassium aluminum sulfate dodecahydrate, mix well, measure the density of the repair fluid and pour it into a 50.8mm×50.8mm×50.8mm test mold to form.

[0097] The repair fluid was prepared according to Examples 1 to 6 and Comparative Examples 1 to 5, and the density and thickening time of the repair fluid slurry, as well as the compressive strength of the consolidated body (50.8mm×50.8mm×50.8mm test mold) at different curing temperatures were measured. Among them, the thickening time and compressive strength test methods were implemented in accordance with the national standard "GBT 19139-2003 Oil Well Cement Test Method"; the density was measured using a method well known in the art, and the results are shown in Tables 1 and 2.

[0098] (1) Comprehensive performance evaluation

[0099] Table 1 Comprehensive performance evaluation table of repair fluid

[0100]

[0101] As shown in Table 1, the repair fluid provided by the present invention has the following significant advantages: (1) Wide application range: within the temperature range of 40 to 180°C, the thickening time is adjustable from 180 to 550 min; the density range is 1.2 to 2.1 g / cm 3 , which can meet the needs of sandwich wall repair work in different blocks, formation pressures and lithologies; (2) High safety: The repair fluid of the present invention has strong resistance to oil-based drilling fluid pollution. Mixing with oil-based drilling fluid in different proportions prolongs the thickening time to a certain extent, and no exothermic or flash coagulation occurs, meeting the safety requirements on site; (3) Strong consolidation and oil-resistance mixing ability: The compressive strength of the solidified body formed by the pure repair fluid is greater than 10MPa, and the compressive strength of the solidified body mixed with 35% oil-based drilling fluid is greater than 5.5MPa; Comparative Example 1 is cement slurry, which cannot be consolidated after being mixed with oil-based drilling fluid; By comparing Example 3, Example 6 and Example 5 (without addition), it is found that the compressive strength of the oil-based drilling fluid mixed with different proportions after adding the oil-resistant corrosion agent is significantly increased, indicating that it has the effect of improving the repair fluid's ability to resist oil-based drilling fluid mixing.

[0102] (2) Evaluation of oil resistance

[0103] Table 2 Evaluation table of repair fluid's anti-oil mixing ability

[0104]

[0105] As shown in Table 2, when the oil-based drilling fluid is not mixed, the oil-resistant corrosion agent has little effect on the thickening time and compressive strength of the repair fluid, and does not affect the construction safety and stability of the repair fluid; but when the oil-based drilling fluid is mixed, the oil-resistant corrosion agent of multiple components is compounded (Example 3), and the compressive strength reduction rate of the mixed 35% oil-based drilling fluid is 17.26%, and the reduction rates of the single component oil-resistant corrosion agent (Comparative Example 2, Comparative Example 3, Comparative Example 4) are 36.36%, 59.38%, and 65.19%, respectively, indicating that the compounded oil-resistant corrosion agent improves the mixing The consolidation ability of oil-based drilling fluid is better, and the best effect is achieved by adding modified pumice powder to a single component. Comparative Example 5 shows that when the modified pumice powder accounts for less than 55% of the oil-based corrosion resistant agent, the compressive strength reduction rate of 35% oil-based drilling fluid is 39.87%, which further illustrates that the modified pumice powder has a large specific surface area, a special porous structure, and strong surface lipophilicity, which is beneficial to the adsorption of oil phase molecules in the oil-based drilling fluid. At the same time, it has a large hydration reaction activity, and plays a major role in improving the oil-resistant mixing ability. It is an essential material in the oil-based corrosion resistant agent and its proportion must be ≥55%.

[0106] (3) Evaluation of oil corrosion resistance and long-term stability

[0107] The 50.8 mm × 50.8 mm × 50.8 mm modules obtained in Example 3 and Comparative Example 1 were placed in a beaker filled with 0# diesel. The mouth of the beaker was sealed with a plastic film. After being immersed in a sealed manner for 1D, 7D, 15D, and 30D at room temperature, the compressive strength and diesel penetration depth ratio were measured. The results are shown in Table 3.

[0108] Table 3 Evaluation table of oil corrosion resistance and long-term stability of repair fluid

[0109]

[0110] It can be seen from Table 3 that after the cement stone is immersed in diesel for 15 days, the diesel immersion depth reaches 100%, the compressive strength decreases by 88.42%, and the 30D compressive strength decreases to 0, indicating that with the increase of the immersion corrosion time, the oil phase completely invades the interior of the cement stone, and the corrosion destroys its internal structure, resulting in a decrease in compressive strength until it is completely destroyed; and after the solidified body formed by the repair liquid provided by the present invention is immersed in diesel for 30 days, the compressive strength increases by 10%, and the diesel immersion depth ratio is only 9.8%, indicating that the oil-resistant corrosion agent can hinder the penetration of the oil phase, ensure the long-term reaction of the active ingredients so that the strength continues to increase, and ensure the long-term stability of the sandwich wall.

[0111] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention, but the present invention is not limited thereto. Those skilled in the art can understand that within the technical concept of the present invention, the technical solution of the present invention can be modified, or some technical features can be combined in any other way. These modifications or combinations do not make the essence of the corresponding technical solution deviate from the spirit and scope of each implementation of the technical solution of the present invention, and should be regarded as the contents disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A sandwich wall repair fluid for oil-based drilling fluid, characterized in that: include: The activator is selected from one or more of sodium carbonate, calcium chloride, calcium oxide and sodium sulfate; The oil corrosion resistant agent is selected from one or more of modified pumice powder, microsilica powder and inorganic salt water purifier.

2. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The oil corrosion resistant agent is selected from modified pumice powder, microsilica powder and inorganic salt water purifier; the mass ratio of the modified pumice powder, microsilica powder and inorganic salt water purifier is (50-100): (20-45): (10-25).

3. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 2, characterized in that: The mass percentage of the modified pumice powder in the oil corrosion resistant agent is greater than or equal to 55%.

4. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The modified pumice powder is calcined pumice powder modified by a silane coupling agent.

5. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The modified pumice powder is prepared according to the following method: A1) mixing pumice powder with an alkaline substance, calcining and activating the mixture, to obtain calcined pumice powder; A2) Under stirring conditions, a silane coupling agent solution is sprayed onto the calcined pumice powder at room temperature by atomization, and after drying, a modified pumice powder is obtained.

6. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 5, characterized in that: The mass ratio of the pumice powder to the alkaline substance is 1:(0.015-0.035); the calcination activation temperature is 300-550°C; the calcination activation time is 3-5h; The silane coupling agent solution is a solution of silane coupling agent and ethanol; the mass ratio of the silane coupling agent to ethanol is (0.4-0.6):1; the mass of the silane coupling agent solution is 0.5%-1.5% of the mass of the calcined pumice powder.

7. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The inorganic salt water purifier is selected from ferric chloride and potassium aluminum sulfate dodecahydrate; the mass ratio of ferric chloride to potassium aluminum sulfate dodecahydrate is (10-20): (0-1).

8. The sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The cement solidifying agent is selected from one or more of aluminate cement, ordinary cement, ultrafine cement and oil well G grade cement; The mineral admixture is selected from one or more of ultra-fine blast furnace slag, tuff powder, zeolite powder, fly ash and burnt shale powder; The density regulator is selected from a weighting agent or a lightening agent; the weighting agent is selected from one or more of barite, hematite and ilmenite; the lightening agent is selected from one or more of perlite beads, hollow glass microspheres and urea-formaldehyde resin microspheres; The flow pattern regulator is selected from one or more of sulfonated aldehyde-ketone condensates, hydroxycarboxylic acid compounds and hydroxypolysaccharide compounds; The retarder is selected from one or more of lignin sulfonate retarders, hydroxycarboxylate retarders, cellulose derivative retarders, AMPS polymer retarders and inorganic-organic polymer oil well cement retarders; The fluid loss reducer is selected from one or more of hydroxycarboxylic acid fluid loss reducers, inorganic compound fluid loss reducers, cellulose derivative fluid loss reducers, AMPS multipolymer fluid loss reducers and inorganic non-metal-organic polymer fluid loss reducers.

9. A method for preparing the sandwich wall repairing fluid for oil-based drilling fluid according to claim 1, characterized in that: The following steps are involved: S1) mixing water, flow pattern regulator, retarder and fluid loss reducer uniformly to obtain slurry preparation water; S2) mixing the slurry preparation water, cement-based solidifying agent, mineral admixture, activator, oil-resistant corrosion agent and density regulator evenly to obtain a sandwich wall repair fluid for oil-based drilling fluid.

10. A method for repairing a sandwich wall, characterized in that: The following steps are involved: B1) Clean the well wall and wellbore; B2) Pumping the oil-based drilling fluid described in any one of claims 1 to 7 into the well with the sandwich wall repair fluid, and then using the drilling fluid to replace the repair fluid. After the repair fluid leaves the drill bit, adjust the position of the drill bit so that the bottom jet tool is at the damaged part of the sandwich wall, and move the drill bit up and down, and dynamically pump the repair fluid until the inside and outside of the drill bit are balanced; B3) Drilling to above the level of repair fluid; B4) Circulate and drain the mixed slurry; B5) Wait for condensation.

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