CN113897186B - Oil-based gel consolidation plugging system for oil-based drilling fluid applicable to malignant leakage stratum and preparation method of oil-based gel consolidation plugging system - Google Patents

Abstract

The invention provides an oil-based gel consolidation plugging system for oil-based drilling fluid suitable for a malignant lost circulation stratum and a preparation method thereof, wherein the oil-based gel consolidation plugging system comprises the following raw materials in parts by mass: 50-60 parts of an oil-based gel system, 15-35 parts of a temperature-sensitive curable material system and 25-45 parts of oil-based cement. The invention also provides a preparation method of the gel consolidation plugging system. The oil-based gel in the plugging system is crosslinked by using a flexible monomer and matched with a rigid unit, so that the structural stability of the gel can be effectively improved; the curable material can be combined with the oil-based gel, and is matched with a medium-high temperature curing agent to realize gradient curing, so that the leakage of the oil-based plugging slurry in the stratum is reduced, and the consolidation strength of the oil-based gel is improved; the capsule type demulsifier is used in the oil-based cement part to adjust the slow release time of the cement, and a plugging layer with oil-based gel as a main part and a curable material and oil-based cement as an auxiliary part is formed, so that the vicious leakage stratum is effectively plugged.

Description

Oil-based gel consolidation plugging for oil-based drilling fluid suitable for malignant loss formation System and its preparation method

technical field

The invention relates to an oil-based gel consolidation plugging system for oil-based drilling fluid suitable for malignant leakage formations and a preparation method thereof, belonging to the technical field of drilling fluid plugging in petroleum exploration and development.

Background technique

As the world's energy is shifting from conventional oil and gas exploration to unconventional oil and gas exploration, the development of unconventional oil and gas such as shale gas has attracted more and more attention. Under the background of the geological conditions of complex formations and the increasing scale of shale gas exploitation, lost circulation has become one of the common downhole complex situations in the development process. Lost circulation may induce downhole complex situations such as pressure drop, well wall collapse, and instability, which not only affect the drilling speed, but also cause huge economic losses, and the requirements for drilling fluid are more stringent. In addition, lost circulation can be divided into four types according to the type of lost channel: porosity lost, fractured lost, dissolved cavern lost and compound lost. According to data, the incidence of lost circulation in the world accounts for 20-50% of the total number of drilling wells, and the loss of vicious lost circulation accounts for 50% of the total loss of lost circulation. Once malignant lost circulation occurs, it is very difficult to deal with it, causing serious economic losses.

At present, for the problem of vicious leakage, domestic and foreign scholars have developed a variety of plugging materials, mainly including polymer gel plugging materials, polymer expanded resin plugging materials, composite plugging materials and other drilling fluid plugging materials, but various products function and performance are different. However, the above-mentioned plugging materials are mainly water-based drilling fluids, and there are few plugging materials suitable for oil-based drilling fluids. Compared with water-based drilling fluid, oil-based drilling fluid has the advantages of inhibiting shale hydration expansion, high temperature resistance, good lubricity, and less damage to oil and gas layers. Since oil-based drilling fluids use oil as the continuous phase, their preparation costs are much higher than those of water-based drilling fluids. Moreover, in the process of drilling with oil-based drilling fluid, vicious leakage formations are often encountered, resulting in a large amount of oil-based drilling fluid loss, which greatly increases the cost of using oil-based drilling fluid.

There are also patent literature reports on gel plugging materials suitable for oil-based drilling fluids. For example, Chinese patent document CN105646763A provides an oil-based gel that can be used for drilling plugging and its preparation method. The oil-based gel has good viscoelasticity and strength, and has excellent plugging performance. Before gluing, it is not limited by the leakage channel, and it is easy to enter the pores or cracks through the pressure difference and polymerize and cross-link in the pore and cracks to form a gel. However, the controllability of the gel formation in complex fractures is relatively poor. Chinese patent document CN105199693A provides an oil-based gel plugging slurry, which is composed of: 35-70 parts of base oil; 5-25 parts of curing agent; 0.1-1 part of activator; 0.5 parts by weight -4 parts of water; 0-60 parts of weighting agent, but the formula of the base gel plugging slurry is relatively simple, and the gel bearing strength is insufficient, so it cannot effectively plug the malignant leakage formation. Chinese patent document CN110144198A provides a gel plugging agent for oil-based drilling fluid, comprising the following components in parts by mass: 3-5 parts of oil-in-water surfactant, 5-15 parts of oil, 2 parts of sodium bentonite ～4 parts, crosslinking agent 8～12 parts, gel forming agent 24～36 parts, retarder 0～1 part, strengthening agent 5～15 parts, weighting agent 5～10 parts, water 100 parts. However, the gelation time of the gel mainly depends on the concentration of the retarder. In complex fractures, the initial and final setting times are difficult to grasp, and the controllability is poor, which may easily cause oil-based drilling fluid loss.

Therefore, it is necessary to develop an oil-based gel plugging material suitable for oil-based drilling fluids with high plugging strength, temperature resistance and good controllability, so as to effectively seal oil-based drilling fluid losses, especially malignant losses. Blocking.

Contents of the invention

Aiming at the deficiencies of the prior art, especially the deficiencies of the existing oil-based gel plugging materials in the malignant loss formation, the controllability of gelation is poor, and the gel bearing strength is low. An oil-based gel consolidation plugging system for oil-based drilling fluid in lost formations and a preparation method thereof. The oil-based gel consolidation plugging system of the present invention mainly includes oil-based gel, temperature-sensitive curable materials and oil-based cement, wherein the oil-based gel is cross-linked with flexible monomers and combined with rigid monomers, which can effectively Improve the structural stability of the gel; the curable material is lipophilic and can be combined with the oil-based gel, with a medium-temperature curing agent and a high-temperature curing agent to achieve gradient curing, reduce the loss of oil-based drilling fluid in the formation, and improve Consolidation strength of oil-based gel; the demulsifier in the oil-based cement part is wrapped by the capsule shell, which is related to the leakage temperature of the formation to adjust the slow-release time of the cement and form an oil-based gel-based, curable material and oil The plugging layer supplemented by base cement can realize the effective plugging of the vicious leakage formation.

Technical scheme of the present invention is as follows:

An oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant loss formations, comprising the following raw materials in parts by mass: 50-60 parts of an oil-based gel system, 15-35 parts of a temperature-sensitive curable material system , Oil-based cement 25-45 parts.

Preferably according to the present invention, the oil-based gel system includes the following raw materials in parts by mass: 100 parts of base oil I, 50-70 parts of polymerized monomers, 1-3 parts of initiator, 5-20 parts of gelling agent, cross-linking 2-6 parts of agent, 3-8 parts of enhancer.

Preferably, the base oil I is diesel or white oil; more preferably, the diesel is 0 ^# diesel.

Preferably, the polymerized monomers include acrylate monomers, alcohol monomers and rigid monomers, wherein the molar ratio of acrylate monomers, alcohol monomers and rigid monomers is 1-3:1:1 ;

Further preferably, the acrylate monomer is methyl methacrylate, glycidyl acrylate or ethylene glycol dimethacrylate; the alcohol monomer is pentaerythritol, diethylene glycol or diethylene glycol Propylene glycol; the rigid monomer is ethylene dibenzoate, trimethyl 1,3,5-benzenetricarboxylate (CAS number: 2672-58-4) or methyl toluate.

Preferably, the initiator is dimethyl azobisisobutyrate, azobisisobutyronitrile or azobisisoheptanonitrile.

Preferably, the gelling agent is dimethyl azelate, trioctyl trimellitate or phenyl alkyl sulfonate; the phenyl alkyl sulfonate is C10-18-phenyl alkyl sulfonate (CAS No.: 70775-94-9).

Preferably, the crosslinking agent is trimethoxysilane, triethoxysilane, 1,1,1-triethyl-3,3,3-trimethyldisiloxane or n-hexyltriethoxy silane.

Preferably, the reinforcing agent is ethyl orthosilicate, methyl orthosilicate or trimethoxysilane.

Preferably according to the present invention, the oil-based gel system is prepared according to the following method:

(1) Add the polymerized monomer into the base oil I, stir until fully dissolved, and obtain the mixed liquid A;

(2) Mix the gelling agent, cross-linking agent and reinforcing agent, and stir evenly to obtain the mixed solution B;

(3) Add mixed solution B into mixed solution A, heat to 65-75°C, stir and mix evenly to obtain mixed solution C;

(4) Add the initiator into the mixed liquid C, stir and react to obtain an oil-based gel system.

Preferably, the stirring rate in step (1) is 600-800r/min, and the stirring time is 15-30min.

Preferably, the stirring rate in step (2) is 400-500r/min, and the stirring time is 10-15min.

Preferably, the stirring rate in step (3) is 800-900r/min, and the stirring time is 20-40min.

Preferably, the initiator described in step (4) is added dropwise in the mixed solution C in the form of ethanol solution of the initiator, and the dropping time is 1-3min; the mass concentration of the initiator in the ethanol solution of the initiator is 0.1-0.2 g/mL, the ethanol solution of the initiator is prepared according to the following method: add the initiator to absolute ethanol, and stir for 15 minutes at a rotational speed of 1000 r/min to obtain the solution.

Preferably, the stirring rate in step (4) is 400-600r/min; the reaction temperature is 90-100°C, and the reaction time is 3-4h.

In the oil-based gel of the present invention, under the action of the initiator, the ester group in the acrylate monomer and the hydroxyl group in the alcohol monomer undergo a polycondensation reaction, and the carbon chain of the alcohol links the long-chain acrylate molecules stand up. The hydroxyl groups on the molecular chains of acrylate monomers and alcohol monomers undergo pairing reactions to form coordination bonds, turning linear polymer chains into complex spatial network structures. In addition, a rigid monomer containing a rigid benzene ring structure is introduced to improve the stability of the structure. At the same time, an organosilicon-based reinforcing agent is introduced. The four valence electrons in the outermost layer of the silicon atom are covalently bonded to the polymerized monomer, making the condensation Glue has high strength and temperature resistance.

Preferably according to the present invention, the temperature-sensitive curable material system includes the following raw materials in parts by mass: 15-25 parts of base oil II, 5-15 parts of temperature-sensitive curable material, and 7-12 parts of compounded curing agent.

Preferably, the base oil II is the same as the base oil I.

Preferably, the temperature-sensitive curing material is bismaleimide resin, thermosetting polyimide resin or cyanate resin; further preferably, the bismaleimide is N,N'-(4 , 4'-methylene diphenyl) bismaleimide; the weight-average molecular weight of the thermosetting polyimide resin is 1500-5000, the elastic modulus is 3-4GPa, the tensile strength is greater than 100MPa, and the thermal expansion The coefficient is 2×10 ^-5 -3×10 ^-5 /°C, and the dielectric constant is 3.0-3.4; the cyanate resin is bisphenol A cyanate, bisphenol F cyanate, bisphenol M cyanate Ester or phenolic cyanate, the weight average molecular weight of the cyanate resin is 2000-4000, and the dielectric constant is 2.8-3.2.

Preferably, the composite curing agent includes a medium-temperature curing agent and a high-temperature curing agent, and the mass ratio of the medium-temperature curing agent to the high-temperature curing agent is 1:1-2, more preferably 1:1.5; the curing temperature of the medium-temperature curing agent 50~100℃, the curing temperature of high temperature curing agent is 110~200℃;

Further preferably, the medium-temperature curing agent is β-hydroxyethylethylenediamine, 2-methylimidazole or low-molecular-weight polyamide; the low-molecular-weight polyamide is low-molecular 650 polyamide resin with a molecular weight of 600-1100 , the density is 0.97-0.99g/cm ³ , the amine value is 200-240mgKOH/g, the viscosity is 1000-10000MPa·s; the high-temperature curing agent is nadic acid anhydride, sebacic acid dihydrazide or boron trifluoride- monoethylamine complex.

Preferably according to the present invention, the temperature-sensitive curable material system is prepared according to the following method: add the temperature-sensitive curable material and compound curing agent to base oil II, and stir at a rate of 1500-2000r/min for 10- 20min, that is.

In the present invention, a combination of a medium-temperature curing agent and a high-temperature curing agent is used to achieve gradient curing, which is beneficial to improving the consistency of the gel at the initial stage, and bonding a certain amount of inert material to reduce the leakage of the plugging slurry. As the formation temperature rises, the plugging slurry becomes thicker and the high-temperature curing agent begins to participate in the polymerization reaction. Due to the action of the medium-temperature curing agent, the curing period of the high-temperature curing agent is shortened and the strength of the gel is improved.

Preferably according to the present invention, the oil-based cement includes the following raw materials in parts by mass: 35-50 parts of base oil III, 50-60 parts of curing main agent, 3-7 parts of wetting and dispersing agent, 5-10 parts of inert material, micro Capsule demulsifier 5-10 parts.

Preferably, the base oil III is the same as the base oil I.

Preferably, the main curing agent is grade G oil well cement, wherein the putty ratio is 0.3.

Preferably, the wetting and dispersing agent is OP-10, polyoxyethylene lauryl ether or zinc stearate.

Preferably, the inert material is asphalt, cottonseed hulls or slag; the particle size of the inert material is 16-30mm.

Preferably, the microcapsule demulsifier is a microcapsule particle with the demulsifier as the core material and the thermoplastic polyurethane material as the wall material; the demulsifier is polyoxyethylene polyoxypropylene stearyl ether, polyoxyethylene polyoxypropylene One or more combinations of polyether and AR demulsifiers; the AR demulsifier is an oil-soluble nonionic polymer formed from alkylphenolic resin (AR resin) and polyoxyethylene and polyoxypropylene Type demulsifier, HLB value is 4-8.

Described microcapsule demulsifier is prepared according to the following method:

(i) Disperse the emulsifier in methylene chloride, add a demulsifier and an isocyanate monomer, and stir and disperse evenly to obtain an oil phase solution at a rotating speed of 1500-2000r/min;

(ii) adding the polyol to water, and stirring for 20-30min at a rotating speed of 1500-2000r/min to obtain an aqueous phase solution;

(iii) Add the water phase solution into the oil phase solution, disperse evenly, then add fluorine-containing vinyl monomer, and stir evenly under the condition of rotating speed of 1000-1500r/min to obtain a monomer mixed solution;

(iv) Add the catalyst to the monomer mixed solution, raise the temperature to 80°C under stirring, and react for 4 hours to obtain a microcapsule emulsion; then cool down to room temperature, centrifuge to obtain a solid product, wash with methanol, and then vacuum-dry at 50°C After 24 hours, the microcapsule demulsifier was obtained.

Further preferably, the emulsifier described in the step (i) is gum arabic, Span or Tween; the Span is Span 20, Span 40, Span 60 or Span 80; the Tween is Tween Wen 20, Tween 40, Tween 60 or Tween 65; the isocyanate monomer is hexamethylene diisocyanate, 2,4-toluene diisocyanate, diphenylmethane diisocyanate or dicyclohexylmethane diisocyanate The ratio of the quality of the emulsifier to the volume of methylene chloride is 0.05-0.5g: 1mL; the ratio of the quality of the demulsifier to the volume of methylene chloride is 0.2-0.7g: 1mL; The ratio of the mass of the body to the volume of dichloromethane is 0.1-0.6g:1mL.

Further preferably, the polyhydric alcohol in step (ii) is 1,4-butanediol, 1,6-hexanediol or polyethylene glycol; the weight average molecular weight of the polyethylene glycol is 600-4000; The ratio of the mass of the polyol to the volume of water is 0.05-0.2g:1mL.

Further preferably, the molar ratio of the polyol in the aqueous phase solution to the isocyanate monomer in the oil phase solution in step (iii) is 1.4-1.5:1.

Further preferably, the fluorine-containing vinyl monomer in step (iii) is tetrafluoroethylene, vinylidene fluoride or chlorotrifluoroethylene; the quality of the fluorine-containing vinyl monomer is the total mass of isocyanate monomers and polyols 20-30%.

Further preferably, the catalyst in step (iv) is zinc acetylacetonate, vanadic anhydride or phthalic anhydride; the amount of the catalyst added is 3-10% of the total mass of isocyanate monomers, polyols and fluorine-containing vinyl monomers.

The shell of the microcapsule demulsifier of the present invention is a thermoplastic polyurethane material, which is polymerized by the isocyanate group in the polyvalent isocyanate monomer and the hydroxyl group in the polyol to generate a polyurethane group, which is then combined with a fluorine-containing vinyl monomer obtained by graft modification of fluorine atoms. Moreover, due to the low surface energy of the fluorine atoms, it is easy to graft to the polyurethane group, which reduces the surface free energy of the polyurethane group and improves the surface hydrophobicity. As the formation temperature rises, the wall material softens, releasing core material. The slow-release time can be adjusted by adjusting the thickness of the capsule wall material according to the formation temperature. When the stirring speed is 10000r/min, a shell with a thickness of 1-5μm can be formed. If the thickness of the shell needs to be increased, the stirring speed can be reduced; The thickness can increase the stirring speed.

Preferably according to the present invention, the oil-based cement is prepared according to the following method:

(a) Disperse the wetting and dispersing agent in base oil III, and stir evenly to obtain dispersion D;

(b) adding the solidified main agent into the dispersion liquid D, and stirring evenly to obtain the dispersion liquid E;

(c) Add the inert material and the microcapsule demulsifier into the dispersion E, and stir evenly to obtain the oil-based cement.

Preferably, the stirring speed described in the step (a) is 3000-4000r/min, and the stirring time is 10-15min; the stirring speed described in the step (b) is 10000-12000r/min, and the stirring time is 20-40min; The stirring speed described in (c) is 3000-4000r/min, and the stirring time is 10-15min.

According to the present invention, the above-mentioned preparation method of the oil-based gel consolidation plugging system for oil-based drilling fluid suitable for malignant leakage formations includes the following steps:

Add oil-based cement and temperature-sensitive curable material system to the oil-based gel system, and stir evenly to obtain an oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant leakage formations; the stirring rate 1500-2000r/min, stirring time 15-30min.

Technical characteristics of the present invention and beneficial effect are as follows:

1. The oil-based gel in the oil-based gel consolidation plugging system of the present invention is flexibly cross-linked with acrylate monomers and alcohol monomers, and introduced rigid monomers containing rigid benzene ring structures to improve Stability of the gel structure. In addition, silicone-based reinforcing agents and crosslinking agents are introduced into the oil-based gel, and the four valence electrons in the outermost layer of the silicon atom are covalently bonded to the oil-soluble monomer, making the gel have higher strength and temperature resistance. It can be combined with temperature-sensitive curable materials and oil-based cement to improve the consolidation strength.

2. The temperature-sensitive curable material system in the oil-based gel consolidation plugging system of the present invention is composed of a temperature-sensitive curing material and a compound curing agent. The compound curing agent is a mixture of a medium-temperature curing agent and a high-temperature curing agent. The combination of medium-temperature curing agent and high-temperature curing agent is used to achieve gradient curing, which is conducive to improving the consistency of the gel at the initial stage, and bonding a certain amount of inert materials to reduce the loss of plugging slurry. As the formation temperature rises, the plugging slurry becomes thicker and the high-temperature curing agent begins to participate in the polymerization reaction. Due to the action of the medium-temperature curing agent, the curing period of the high-temperature curing agent is shortened and the strength of the gel is improved.

3. The oil-based cement part in the oil-based gel consolidation plugging system of the present invention uses a microcapsule demulsifier. As the temperature gradually increases, the shell of the microcapsule demulsifier begins to soften, and the oil phase and the water phase are broken. Gradually separated under the action of the emulsion, due to the amphiphilic properties of the surfactant, the oil-based cement cannot be completely replaced, and under the combined action of the medium-temperature curing agent and the high-temperature curing agent of the temperature-sensitive material, the three are connected to each other; Oil-based gel-based plugging layer supplemented by curable materials and oil-based cement. The mosaic effect of the three improves the strength of the plugging layer and realizes effective plugging of malignant leakage formations. And the microcapsule demulsifier of the present invention can adjust the sustained release time by adjusting the thickness of the capsule wall material according to the formation temperature.

4. The oil-based gel consolidation plugging system in the present invention has good gelation controllability and high pressure-bearing strength of the gel, which can realize effective plugging of oil-based drilling fluid loss, especially malignant loss formation.

Description of drawings

Figure 1 shows the gelation time of the oil-based gel consolidation plugging system in Test Example 1 under different gelling agent concentrations.

Figure 2 shows the gel strength of the oil-based gel consolidation plugging system in Test Example 1 at different concentrations of reinforcing agents.

Detailed ways

The present invention will be further described below through specific examples, but not limited thereto.

The raw materials used in the examples are conventional materials unless otherwise specified, and are commercially available. The methods used in the examples, unless otherwise specified, are all prior art.

The weight-average molecular weight of the thermosetting polyimide used in the examples is 5000, the modulus of elasticity is 3.5GPa, the tensile strength is 110MPa, the coefficient of thermal expansion is 3×10 ^-5 /°C, and the dielectric constant is 3.4. Yunnan Lilian Biology Co., Ltd. Limited is available;

Grade G oil well cement is available from Shandong Wenqu New Material Technology Co., Ltd.;

Polyoxyethylene polyoxypropylene stearyl ether, available from Nantong Qianhe Chemical Co., Ltd.;

The HLB value of the AR type demulsifier is about 4 to 8, and it is sold by Guangdong Shanmei Environmental Technology Co., Ltd.

The test method for the maximum bearing plugging pressure of the oil-based gel consolidated plugging system prepared in the examples is as follows:

The simulated crack plugging test is used to test the maximum pressure sealing pressure of the prepared oil-based gel consolidation plugging system. The specific operation steps are: use the high temperature and high pressure dynamic plugging evaluation device, open the high temperature and high pressure dynamic plugging evaluation device Set the formation temperature (80-150°C) on the temperature controller to simulate the formation temperature condition; turn on the constant flow pump, and inject the above-prepared oil-based oil into the core holder equipped with the steel column fracture core model For the gel consolidation plugging system, the injection pressure is recorded in real time, and the total injection volume is the volume of 50 fracture core models; during the injection process of the plugging system, the injection pressure gradually increases, and the leakage of the oil-based gel consolidation plugging system The amount gradually decreases to 0, indicating that the oil-based gel consolidation plugging system in the fracture forms a plugging layer and seals the fracture; continue to inject until the plugging system flows out from the outlet end of the core holder again, indicating that the fracture The plugging layer formed by the oil-based gel-consolidated plugging system is broken through, and the highest pressure value measured is the maximum bearing plugging pressure of the oil-based gel-consolidated plugging slurry.

Example 1

An oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant loss formations, comprising the following raw materials in parts by mass: 50 parts of an oil-based gel system, 15 parts of a temperature-sensitive curable material system, and an oil-based cement 35 servings.

The oil-based gel system includes the following raw materials in parts by mass: 100 parts of base oil I, 60 parts of polymerized monomer, 1 part of initiator, 6 parts of gelling agent, 5 parts of crosslinking agent, and 5 parts of reinforcing agent; base oil I It is 0 ^# diesel oil; the polymerized monomer is a mixture of ethylene glycol dimethacrylate, pentaerythritol, and 1,3,5-benzenetricarboxylate trimethyl ester, and in the mixture, ethylene glycol dimethacrylate, pentaerythritol and 1 , the molar ratio of 3,5-trimethylbenzenetricarboxylate is 2:1:1; the initiator is dimethyl azobisisobutyrate; the gelling agent is trioctyl trimellitate; the crosslinking agent It is n-hexyltriethoxysilane; the reinforcing agent is trimethoxysilane.

The temperature-sensitive curable material system includes the following raw materials in parts by mass: 20 parts of base oil II, 15 parts of temperature-sensitive curing material, and 7 parts of compound curing agent; the base oil II is 0 ^# diesel; the temperature-sensitive curing material is thermosetting polyamide Imine; compound curing agent includes medium-temperature curing agent and high-temperature curing agent, the mass ratio of medium-temperature curing agent to high-temperature curing agent is 1:1.5, the medium-temperature curing agent is β-hydroxyethylethylenediamine, and the high-temperature curing agent is decane acid dihydrazide.

The oil-based cement includes the following raw materials in parts by mass: 35 parts of base oil III, 50 parts of curing main agent, 4 parts of wetting and dispersing agent, 6 parts of inert material, and 5 parts of microcapsule demulsifier; base oil III is 0 ^# diesel oil; The main curing agent is grade G oil well cement, and the putty ratio is 0.3; the wetting and dispersing agent is polyoxyethylene lauryl ether; the inert material is cotton seed hulls, and the particle size is 20mm;

Described microcapsule demulsifier is prepared according to the following method:

(i) Disperse 5g of emulsifier gum arabic in 50mL of dichloromethane, then add 30g of demulsifier (polyoxyethylene polyoxypropylene stearyl ether and AR type demulsifier are mixed at a mass ratio of 1:1), 10g of hexaethylene Methyl diisocyanate, under the condition of rotating speed of 2000r/min, stir and disperse evenly to obtain an oil phase solution;

(ii) Add 10 g of 1,6-hexanediol into 100 mL of water, and stir for 30 min at a rotation speed of 2000 r/min to obtain an aqueous phase solution;

(iii) adding the aqueous phase solution into the oil phase solution, and dispersing evenly, then adding 6g of chlorotrifluoroethylene, and stirring evenly at room temperature at a speed of 1000r/min to obtain a monomer mixed solution;

(iv) Add 2.6 g of catalyst zinc acetylacetonate into the monomer mixed solution, raise the temperature to 80° C. under the stirring condition of 10,000 r/min, react for 4 hours, and obtain a microcapsule emulsion; then cool it down to room temperature, and obtain a solid product by centrifugation , washed with methanol, and then vacuum-dried at 50° C. for 24 hours to obtain a microcapsule demulsifier.

The preparation method of the above-mentioned oil-based gel consolidation plugging system suitable for oil-based drilling fluid vicious leakage formations includes the following steps:

(1) Preparation of oil-based gel system

Add polymerized monomers to base oil I, stir for 20 minutes at a speed of 700r/min, and fully dissolve to obtain a mixed solution A; mix the gelling agent, crosslinking agent and reinforcing agent, and Stir for 10 minutes and stir evenly to obtain mixed solution B; add mixed solution B to mixed solution A, heat to 70°C, and stir and mix for 30 minutes at a speed of 800r/min to obtain mixed solution C; add the initiator to absolute ethanol , stirring for 15min at a rotational speed of 1000r/min to obtain an initiator ethanol solution with a concentration of 0.1g/mL; add the initiator ethanol solution dropwise to the mixed solution C for 2min; /min at 95°C for 4 hours to obtain an oil-based gel system.

(2) Preparation of temperature-sensitive curable material system

Add the temperature-sensitive curable material and compound curing agent into base oil II, and stir for 15 min at a speed of 2000 r/min to obtain a temperature-sensitive curable material system.

(3) Preparation of oil-based cement

Disperse the wetting and dispersing agent in the base oil III, stir for 10 minutes at a speed of 4000r/min, and stir evenly to obtain a dispersion D; add the main curing agent to the dispersion D, and stir at a speed of 12000r/min Stir for 30 minutes to obtain dispersion E; add inert materials and microcapsule demulsifiers to dispersion E, and stir for 10 minutes at a speed of 4000 r/min to obtain oil-based cement.

(4) Preparation of oil-based gel consolidation plugging system

Add the oil-based cement and temperature-sensitive curable material system to the oil-based gel system, and use a high-speed mixer to stir at a speed of 2000r/min for 20 minutes to obtain the product.

The oil-based gel consolidation plugging system prepared in this example was subjected to the maximum pressure plugging pressure test, and the specific test conditions were as follows: test a: the leakage rate was 50m ³ /h, and the temperature was 100°C; test b: the leakage rate 60m ³ /h, temperature 110℃; test c: leakage rate is 70m ³ /h, temperature 120℃; test d: leakage rate is 80m ³ /h, temperature 130℃, the leakage rate in the test is crack Table 1 shows the leakage rate of the core model, the change of injection pressure over time during the test and the maximum containment plugging pressure.

Table 1

It can be seen from Table 1 that when the leakage rate is 50m ³ /h and the temperature is 100°C, the initial plugging pressure is 3.7MPa in 1h, and the maximum plugging pressure is 8.2MPa in 4h. After 5 hours, the plugging layer has been damaged, and the pressure has gradually dropped to 5.3MPa. When the leakage rate is 60m ³ /h and the temperature is 110℃, the initial plugging pressure is 3.6MPa in 1h, and the maximum plugging pressure is 8.3MPa in 4h, and the plugging layer has appeared in 5h Destruction, the pressure gradually dropped to 5.3MPa. In test b, at the initial stage of the injection stage, due to the increase of cracks, the temperature change was small. In the case of no adjustment of the curing agent ratio, the plugging strength was slightly lower than that of test a at the same time period. After 4 hours, the plugging strength reaches the maximum value. When the leakage rate is 70m ³ /h and the temperature is 120℃, the initial plugging pressure is 3.7MPa in 1h, and the maximum plugging pressure is 8.5MPa in 4h, and the plugging layer has appeared in 5h After failure, the pressure gradually decreased to 5.6MPa, and the leakage rate was 70m ³ /h. Due to the increase in temperature, the gel consolidation plugging system solidified earlier than test b, so its plugging strength was slightly higher than test b. When the leakage rate is 80m ³ /h and the temperature is 130℃, the initial plugging pressure is 2.0MPa in 1h, and the maximum plugging pressure is 8.6MPa in 4h, and the plugging layer has appeared in 5h The pressure gradually dropped to 5.8MPa. In test d, at the initial stage of plugging, due to the increase of cracks, even though the curing effect was advanced due to the increase of temperature, the oil-based gel consolidation system did not form effective plugging. Therefore, the sealing The plugging pressure in the initial stage of plugging is low, and then the plugging pressure gradually increases, and due to the high temperature, the plugging pressure in the subsequent stage rises relatively quickly, reaching the maximum at 4 hours, indicating that the oil-based gel consolidated plugging pressure The leakage system was successfully plugged, and then with the pressure gradually increasing, the plugging layer gradually failed. Moreover, it can be seen from Table 1 that the gel consolidation plugging system of this example has strong plugging strength for fractures at different temperatures and different loss rates, and can achieve effective plugging of malignant loss formations.

Example 2

An oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant loss formations is as described in Example 1, the difference is: ethylene glycol dimethacrylate, pentaerythritol and 1,3,5 - The molar ratio of trimethylbenzenetricarboxylate is 1:1:1.

The preparation method of the above-mentioned oil-based gel consolidation plugging system for oil-based drilling fluid suitable for malignant loss formations is as described in Example 1.

The oil-based gel consolidation plugging system prepared in this example was subjected to the maximum pressure plugging pressure test, and the specific test conditions were as follows: test a: the leakage rate was 50m ³ /h, and the temperature was 100°C; test b: the leakage rate 60m ³ /h, temperature 110°C; test c: leakage rate 70m ³ /h, temperature 120°C; test d: leakage rate 80m ³ /h, temperature 130°C, the injection pressure during the test process changes with time Table 2 shows the change of and the maximum bearing plugging pressure.

Table 2

In this embodiment, the molar ratio of ethylene glycol dimethacrylate, pentaerythritol and 1,3,5-benzenetricarboxylate trimethyl ester is 1:1:1, and the performance is slightly worse than that of Example 1, mainly due to the Glycol dimethacrylate is mainly responsible for the flexible part in the oil-based gel system. When there is less ethylene glycol dimethacrylate, the strength of the cross-linked structure formed by the polymerization product is worse than that of Example 1, and the macroscopic performance is gelatinous. Glue strength and maximum plugging pressure are slightly lower than Example 1.

Example 3

An oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant loss formations is as described in Example 1, the difference is: ethylene glycol dimethacrylate, pentaerythritol and 1,3,5 - The molar ratio of trimethylbenzenetricarboxylate is 3:1:1.

The preparation method of the above-mentioned oil-based gel consolidation plugging system for oil-based drilling fluid suitable for malignant loss formations is as described in Example 1.

The oil-based gel consolidation plugging system prepared in this example was subjected to the maximum pressure plugging pressure test, and the specific test conditions were as follows: test a: the leakage rate was 50m ³ /h, and the temperature was 100°C; test b: the leakage rate 60m ³ /h, temperature 110°C; test c: leakage rate 70m ³ /h, temperature 120°C; test d: leakage rate 80m ³ /h, temperature 130°C, the injection pressure during the test process changes with time Table 3 shows the change of and the maximum bearing plugging pressure.

table 3

In this embodiment, the molar ratio of ethylene glycol dimethacrylate, pentaerythritol and 1,3,5-trimethyl benzenetricarboxylate is 3:1:1, and the performance is slightly worse than that of Example 1, mainly due to the Glycol dimethacrylate is responsible for the flexible cross-linking part in the oil-based gel system, and 1,3,5-benzenetricarboxylate is responsible for the rigid part in the gel system. With the introduction of an appropriate amount of rigid units, the gel The stability of the system is enhanced, and the strength of the gel is increased. However, as the concentration of ethylene glycol dimethacrylate in the system continues to increase, the proportion of flexible parts is too high, the crosslinking density of the gel system is high, the stretchability of the chain becomes smaller, and the crosslinking stability of the system continues to decline , the macroscopic performance is that the gel strength is insufficient, and the maximum plugging pressure is reduced. Therefore, the proportion of ethylene glycol dimethacrylate in this example is slightly higher than in Example 1, and the gel strength and maximum plugging pressure of the obtained oil-based gel-solidified plugging system are slightly lower than in Example 1.

Example 4

An oil-based gel consolidation plugging system for oil-based drilling fluids suitable for malignant loss formations is as described in Example 1, the difference is: 40 parts of oil-based gel system, 20 parts of temperature-sensitive curable material system , 40 parts of oil-based cement.

The preparation method of the above-mentioned oil-based gel consolidation plugging system for oil-based drilling fluid suitable for malignant loss formations is as described in Example 1.

The oil-based gel consolidation plugging system prepared in this example was subjected to the maximum pressure plugging pressure test, and the specific test conditions were as follows: test a: the leakage rate was 50m ³ /h, and the temperature was 100°C; test b: the leakage rate 60m ³ /h, temperature 110°C; test c: leakage rate 70m ³ /h, temperature 120°C; test d: leakage rate 80m ³ /h, temperature 130°C, the injection pressure during the test process changes with time Table 4 shows the change of and the maximum bearing plugging pressure.

Table 4

Compared with the oil-based gel system in Example 1, the performance of the oil-based gel consolidation plugging system in this example is slightly worse. This is mainly due to the increase of curable material in the early stage of curing, before the oil-based gel forms a plugging layer, the bonding effect of the curable material is enhanced, resulting in a slight increase in the overall plugging pressure compared with the original component. As the oil-based gel gradually gelled, the maximum plugging capacity of the plugging layer decreased slightly due to a slight decrease in the fraction of the oil-based gel.

Comparative example 1

An oil-based gel consolidation plugging system is as described in Example 1, except that no oil-based cement is added to the oil-based gel consolidation plugging system.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 5 below.

table 5

time/h 1 2 3 4 5 Plugging pressure/MPa 1.7 2.4 2.7 3.5 1.2

It can be seen from Table 5 that no oil-based cement was added in this comparative example, and the plugging pressure of the obtained oil-based gel consolidated plugging system in each time period was lower than that of Example 1 of the present invention. When cement-based, the oil-based gel consolidation plugging system lacks the curing effect of oil-based cement, resulting in a substantial decrease in the overall strength of the consolidation plugging system.

Comparative example 2

An oil-based gel consolidation plugging system is as described in Example 1, except that no temperature-sensitive curable material is added to the temperature-sensitive curable material system.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 6 below.

Table 6

time/h 1 2 3 4 5 Plugging pressure/MPa 1.9 2.7 4.2 4.7 2.3

It can be seen from Table 6 that no temperature-sensitive curing material was added in this comparative example, and the plugging pressure of the obtained oil-based gel consolidated plugging system in each time period was lower than that of Example 1 of the present invention, mainly because The lack of temperature-sensitive curing materials reduces the consistency of the oil-based gel-consolidated plugging system. Compared with the addition of temperature-sensitive curing materials, the leakage volume of the oil-based gel-consolidated plugging system increases and the plugging pressure decreases.

Comparative example 3

An oil-based gel consolidation plugging system is as described in Example 1, except that no compound curing agent is added to the temperature-sensitive curable material part of the oil-based gel consolidation plugging system.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 7 below.

Table 7

time/h 1 2 3 4 5 Plugging pressure/MPa 2.1 3.5 4.6 5.7 3.5

It can be seen from Table 7 that under the same conditions as the loss rate of 50m ³ /h and the temperature of 100℃, the oil-based gel consolidation plugging system is under pressure at the initial stage and the plugging pressure is small, and it is plugged after 4 hours of injection. The pressure reaches the maximum value, and with the increase of injection volume, the plugging layer is gradually destroyed and unstable. Due to the lack of compound curing agent, gradient curing cannot be realized in the oil-based gel consolidation plugging system, and the formation temperature is used to increase the consistency of the temperature-sensitive curing material. Compared with the system adding curing agent, the initial pressure sealing The plugging capacity is weak; and the pressure-bearing plugging capacity of the whole stage is also worse than that of Example 1 of the present invention.

Comparative example 4

An oil-based gel consolidation plugging system is as described in Example 1, wherein the polymerized monomers of the oil-based gel are pentaerythritol and 1,3,5-trimethyl benzenetricarboxylate (mass ratio is 1:1 ), does not contain the acrylate monomer ethylene glycol dimethacrylate.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 8 below.

Table 8

time/h 1 2 3 4 5 Plugging pressure/MPa 2.4 3.3 4.3 5.0 3.4

It can be seen from Table 8 that the performance of the obtained oil-based gel consolidation system is worse than that of Example 1 of the present invention without adding acrylate monomers in this comparative example. This is mainly due to the fact that ethylene glycol dimethacrylate mainly bears the flexible part in the oil-based gel system. When no ethylene glycol dimethacrylate is added, the polymerized product cannot form an effective cross-linked structure, and the cross-linked The intention of the structure cannot be fully realized, and the macroscopic performance is that the gel strength is insufficient, and the maximum plugging pressure is reduced.

Comparative example 5

An oil-based gel consolidation plugging system is as described in Example 1, wherein the polymerized monomers in the oil-based gel are ethylene glycol dimethacrylate and 1,3,5-benzenetricarboxylic acid trimethyl ester (The mass ratio is 2:1), does not contain alcohol monomers.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 9 below.

Table 9

time/h 1 2 3 4 5 Plugging pressure/MPa 2.3 3.1 3.8 4.5 3.2

It can be seen from Table 9 that, without adding alcohol monomers in this comparative example, the performance of the obtained oil-based gel consolidation system is worse than that of Example 1 of the present invention. This is mainly because the polymerization product cannot form an effective cross-linked spatial network structure without adding alcohol monomers. Therefore, the gel strength of the obtained oil-based gel consolidation system is insufficient and the maximum plugging pressure is low.

Comparative example 6

An oil-based gel consolidation plugging system is as described in Example 1, wherein the polymerized monomers of the oil-based gel are ethylene glycol dimethacrylate and pentaerythritol (mass ratio is 2:1), and do not contain rigid monomer.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 10 below.

Table 10

time/h 1 2 3 4 5 Plugging pressure/MPa 2.5 3.5 4.4 5.2 3.5

It can be seen from Table 10 that in this comparative example, no rigid monomer is added, and the performance of the obtained oil-based gel consolidation system is worse than that of Example 1 of the present invention. This is mainly because 1,3,5-trimethyl benzenetricarboxylate bears the rigid part in the gel system, and the introduction of an appropriate amount of rigid units increases the stability of the gel system and increases the strength of the gel. But do not add rigid monomer, the rise of ethylene glycol dimethacrylate concentration in the system, the crosslinking density of the gel system is large, the stretchability of the chain becomes smaller, and the crosslinking stability of the system continues to decline, therefore, the obtained The gel strength of the oil-based gel consolidation system is insufficient, and the maximum plugging pressure is low.

Comparative example 7

An oil-based gel consolidation plugging system is as described in Example 1, wherein the polymerized monomers of the oil-based gel are butyl acrylate, pentaerythritol and 1,3,5-trimethyl benzenetricarboxylate.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 11 below.

Table 11

time/h 1 2 3 4 5 Plugging pressure/MPa 2.8 3.7 5.0 5.5 3.2

It can be seen from Table 11 that in this comparative example, butyl acrylate was used as the acrylate monomer, and the performance of the obtained oil-based gel consolidation system was worse than that of Example 1 of the present invention. This is because the acrylate monomer of the present invention, under the action of the initiator, the carbon chain combines the long-chain acrylate molecular chains relatively more closely, and the crosslinking stability of the system is improved. Therefore, the gel strength of the oil-based gel consolidation system obtained by adding butyl acrylate in this comparative example was insufficient, and the maximum plugging pressure decreased.

Comparative example 8

An oil-based gel consolidation plugging system is as described in Example 1, wherein the polymerized monomers in the oil-based gel are ethylene glycol dimethacrylate, pentaerythritol and styrene.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 12 below.

Table 12

time/h 1 2 3 4 5 Plugging pressure/MPa 2.9 4.2 5.2 5.7 3.3

It can be seen from Table 12 that in this comparative example, styrene is used as a rigid monomer, and the performance of the obtained oil-based gel consolidation system is worse than that of Example 1 of the present invention. This is because compared with 1,3,5-trimethyl benzenetricarboxylate, the vinyl electrons in styrene are conjugated with the benzene ring, and only one hydrogen bond is accepted by the monomer free radical of styrene monomer during polymerization. The polymerization reaction of the body occurs, the number of polymerization sites is small, and the crosslinking stability of the system is reduced. In addition, styrene acts as a rigid monomer in the gel system to undertake the skeleton structure in the system, and the tightness of the rigid monomer in the spatial network structure directly determines the overall strength of the gel. 1,3,5-Benzenetricarboxylic acid Trimethyl esters are more compact during the cross-linking process that builds the backbone. Therefore, the gel strength of the oil-based gel consolidation system obtained by adding styrene in this comparative example is insufficient, and the maximum plugging pressure decreases.

Comparative example 9

An oil-based gel consolidated plugging system is as described in Example 1, except that the reinforcing agent is DH-1 reinforcing agent.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 13 below.

Table 13

time/h 1 2 3 4 5 Plugging pressure/MPa 3.2 4.7 6.3 7.1 4.0

It can be seen from Table 13 that in this comparative example, DH-1 strengthening agent was used instead of the silicone-based strengthening agent of the present invention, and the performance of the obtained oil-based gel consolidation system was worse than that of Example 1 of the present invention. This is because the strengthening agent used in the present invention is an organosilicon type strengthening agent, and the four valence electrons in the outermost layer of the silicon atom are covalently bonded to the polymerized monomer, so that the gel has relatively high strength and temperature resistance. However, the strengthening agent used in Comparative Example 9 has no above-mentioned effect, therefore, the performance of the obtained oil-based gel consolidation system is worse than that of Example 1 of the present invention.

Comparative example 10

An oil-based gel consolidation plugging system is as described in Example 1, except that the mass ratio of the medium-temperature curing agent to the high-temperature curing agent in the compounded curing agent is 2:1.

Under the conditions of a loss rate of 50m ³ /h and a temperature of 100°C, the maximum bearing plugging pressure of the oil-based gel consolidation plugging system prepared in this comparative example was tested, and the results are shown in Table 14 below.

Table 14

time/h 1 2 3 4 5 Plugging pressure/MPa 3.9 5.4 6.5 7.7 4.3

In this comparative example, the ratio of medium-temperature curing agent and high-temperature curing agent was changed, and the maximum pressure-bearing plugging pressure of the obtained oil-based gel consolidation plugging system was slightly worse than that of Example 1 of the present invention, indicating that the medium-temperature curing agent and high-temperature curing The proportion of the agent has a certain influence on the plugging strength of the oil-based gel consolidated plugging system, and the above-mentioned proportion needs to be controlled within the scope of the present invention.

Test example 1

Gelling time: The construction time is an important factor to ensure downhole safety, but the temperature gradient of wells in different formations is different, and the leakage points of different wells in the same formation may also be different, resulting in temperature differences. Therefore, we need to ensure that the gelation time of the oil-based gel consolidation plugging system in different well sections is controllable. The present invention regulates the gelation of the oil-based gel system by adjusting the proportion of the gelling agent in the oil-based gel system. Time, so as to regulate the gelation time of the entire plugging system.

The specific conditions are as described in Example 1, the difference is that the addition of the gelling agent is changed to 5 parts, 6 parts, 7 parts, 8 parts, 9 parts and 10 parts, and the remaining component additions are constant to adjust The gelation time of chemical gels. The result is shown in Figure 1.

It can be seen from Figure 1 that with the continuous increase of the amount of gelling agent added to the oil-based gel system, the gelling time of the oil-based gel is gradually shortening. When the amount of gelling agent added is 5 parts, The gelling time of oil-based gel was the longest, reaching 4.7h. When the amount of gelling agent added was 10 parts, the gelation time of oil-based gel was the shortest, reaching 3.2h. With the gradual increase of the amount of gelling agent added, the number of active groups participating in the cross-linking reaction increases continuously, the probability of interaction between the reactive groups increases continuously, the speed of forming a network mechanism in the gel system is continuously accelerated, and the gelation time is continuously reduced. . Based on the time consideration of field application, the addition amount of gelling agent is between 6-7 parts.

Gelling strength: In order to effectively seal the lost formation, the oil-based gel consolidation plugging system was tested for gelling strength using a high-temperature and high-pressure displacement device. The test conditions were that the leakage rate was 50m ³ /h and the temperature was 100°C. Wherein the maximum pressure-bearing plugging pressure is the gelling strength; in the present invention, the gelling strength of the oil-based gel in the oil-based gel consolidation plugging system is regulated by adjusting the addition amount of the reinforcing agent.

The specific conditions are as described in Example 1, the difference is that the addition of the strengthening agent is changed by 1 part, 2 parts, 3 parts, 4 parts, 5 parts and 6 parts respectively, and the addition of the remaining components is constant to adjust the chemical condensation. Glue strength. The result is shown in Figure 2.

It can be seen from Figure 2 that with the increase of the proportion of the enhancer in the oil-based gel system, the gelling strength of the oil-based gel increases gradually and then decreases slightly. When the amount of the enhancer is 1 part, the oil-based gel The strength of base gel is the lowest, the strength is 6.1MPa, and when the amount of reinforcing agent is 5 parts, the strength of oil-based gel is the highest, the strength is 8.2MPa. With the gradual increase of the proportion of the reinforcing agent in the gel system, the dispersibility of the gel system gradually increases, the fluidity of the gel system gradually decreases, and the interior of the gel system is gradually connected tightly to achieve good mechanical strength. When the reinforcing agent The strength of the oil-based gel is greatest when the amount added is 5 parts.

In addition, in the present invention, a medium-temperature curing agent is combined with a high-temperature curing agent to achieve gradient curing, which is beneficial to increase the consistency of the gel at the initial stage, and bind a certain amount of inert materials to reduce the leakage of the gel system. The consistency can be adjusted by adjusting the ratio of medium temperature curing agent to high temperature curing agent.

Claims (10)

1. An oil-based gel consolidation plugging system for an oil-based drilling fluid suitable for a malignant lost circulation stratum is characterized by comprising the following raw materials in parts by mass: 50-60 parts of an oil-based gel system, 15-35 parts of a temperature-sensitive curable material system and 25-45 parts of oil-based cement;

the oil-based gel system comprises the following raw materials in parts by mass: 100 parts of base oil I, 50-70 parts of polymerized monomer, 1-3 parts of initiator, 5-20 parts of gelling agent, 2-6 parts of cross-linking agent and 3-8 parts of reinforcing agent; the polymerization monomers comprise acrylate monomers, alcohol monomers and rigid monomers, wherein the molar ratio of the acrylate monomers to the alcohol monomers to the rigid monomers in the polymerization monomers is 1-3; the acrylate monomer is glycidyl acrylate or ethylene glycol dimethacrylate; the alcohol monomer is pentaerythritol, diethylene glycol or dipropylene glycol; the rigid monomer is ethylene dibenzoate or trimethyl 1,3, 5-benzenetricarboxylate; the gelling agent is dimethyl azelate or trioctyl trimellitate; the cross-linking agent is trimethoxy silane, triethoxy silane, 1-triethyl-3, 3-trimethyl disiloxane or n-hexyl triethoxy silane; the reinforcing agent is tetraethoxysilane, methyl orthosilicate or trimethoxy silane;

the oil-based gel system is prepared according to the following method:

(1) Adding a polymerization monomer into the base oil I, and stirring until the polymerization monomer is fully dissolved to obtain a mixed solution A;

(2) Mixing the gelling agent, the cross-linking agent and the reinforcing agent, and uniformly stirring to obtain a mixed solution B;

(3) Adding the mixed solution B into the mixed solution A, heating to 65-75 ℃, and uniformly stirring and mixing to obtain a mixed solution C;

(4) Adding an initiator into the mixed solution C, and stirring for reaction to obtain an oil-based gel system;

the temperature-sensitive curable material system comprises the following raw materials in parts by mass: 15-25 parts of base oil II, 5-15 parts of temperature-sensitive curing material and 7-12 parts of compound curing agent; the compound curing agent comprises a medium-temperature curing agent and a high-temperature curing agent, wherein the curing temperature of the medium-temperature curing agent is 50-100 ℃, and the curing temperature of the high-temperature curing agent is 110-200 ℃;

the oil-based cement comprises the following raw materials in parts by mass: 35-50 parts of base oil III, 50-60 parts of curing main agent, 3-7 parts of wetting dispersant, 5-10 parts of inert material and 5-10 parts of microcapsule demulsifier; the curing main agent is G-grade oil well cement, wherein the oil-cement ratio is 0.3.

2. The oil-based gel consolidation plugging system for the oil-based drilling fluid as claimed in claim 1, wherein the base oil I is diesel oil or white oil; the initiator is dimethyl azodiisobutyrate, azodiisobutyronitrile or azodiisoheptonitrile.

3. The oil-based gel consolidation plugging system for oil-based drilling fluid according to claim 1, wherein in the step (1), the stirring speed is 600-800r/min, and the stirring time is 15-30min; in the step (2), the stirring speed is 400-500r/min, and the stirring time is 10-15min; in the step (3), the stirring speed is 800-900r/min, and the stirring time is 20-40min; in the step (4), the initiator is dripped into the mixed solution C in the form of an initiator ethanol solution for 1-3min; the mass concentration of the initiator in the initiator ethanol solution is 0.1-0.2g/mL, and the initiator ethanol solution is prepared by the following method: adding an initiator into absolute ethyl alcohol, and stirring for 15min under the condition that the rotating speed is 1000r/min to obtain the emulsion; in the step (4), the stirring speed is 400-600r/min; the reaction temperature is 90-100 ℃, and the reaction time is 3-4h.

4. The oil-based gel consolidation plugging system for oil-based drilling fluid of claim 1, wherein the base oil II is the same as the base oil I;

the temperature-sensitive curing material is bismaleimide resin, thermosetting polyimide resin or cyanate resin;

the mass ratio of the medium-temperature curing agent to the high-temperature curing agent is 1-2.

5. The oil-based gel consolidation plugging system for the oil-based drilling fluid according to claim 4, wherein the mass ratio of the medium-temperature curing agent to the high-temperature curing agent is 1.

6. The oil-based gel consolidation plugging system for the oil-based drilling fluid according to claim 1, wherein the medium-temperature curing agent is β -hydroxyethylethylenediamine, 2-methylimidazole or low molecular polyamide; the high-temperature curing agent is nadic anhydride, sebacic dihydrazide or boron trifluoride-monoethylamine complex.

7. The oil-based gel consolidation plugging system for the oil-based drilling fluid as claimed in claim 1, wherein the temperature-sensitive curable material system is prepared by the following method: and adding the temperature-sensitive curing material and the compound curing agent into the base oil II, and stirring for 10-20min at the speed of 1500-2000r/min to obtain the temperature-sensitive curing oil.

8. The oil-based gel consolidation plugging system for oil-based drilling fluids according to claim 1, wherein the base oil iii is the same as base oil i; the wetting dispersant is OP-10, polyoxyethylene lauryl ether or zinc stearate; the inert material is asphalt, cottonseed hulls or slag; the particle size of the inert material is 16-30mm; the microcapsule demulsifier is microcapsule particles which take the demulsifier as a core material and take a thermoplastic polyurethane material as a wall material; the demulsifier is one or the combination of two of polyoxyethylene polyoxypropylene octadecanol ether and AR type demulsifier.

9. The oil-based gel consolidation plugging system for oil-based drilling fluids according to claim 1, wherein the oil-based cement is prepared by the following method:

(a) Dispersing the wetting dispersant in the base oil III, and uniformly stirring to obtain a dispersion liquid D;

(b) Adding the curing main agent into the dispersion liquid D, and uniformly stirring to obtain a dispersion liquid E;

(c) Adding an inert material and a microcapsule demulsifier into the dispersion liquid E, and uniformly stirring to obtain oil-based cement;

in the step (a), the stirring speed is 3000-4000r/min, and the stirring time is 10-15min; in the step (b), the stirring speed is 10000-12000r/min, and the stirring time is 20-40min; in the step (c), the stirring speed is 3000-4000r/min, and the stirring time is 10-15min.

10. The preparation method of the oil-based gel consolidation plugging system for oil-based drilling fluid of any one of claims 1 to 9, comprising the steps of:

adding the oil-based cement and the temperature-sensitive curable material system into the oil-based gel system, and uniformly stirring to obtain an oil-based gel consolidation plugging system for the oil-based drilling fluid suitable for the malignant lost formation; the stirring speed is 1500-2000r/min, and the stirring time is 15-30min.

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