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
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 Download PDFInfo
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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
Technical Field
The invention relates to an oil-based gel consolidation plugging system for oil-based drilling fluid suitable for a malignant lost circulation stratum and a preparation method thereof, belonging to the technical field of drilling fluid plugging in petroleum exploration and development.
Background
Along with the change of world energy from conventional oil gas exploration to unconventional oil gas exploration, the development of unconventional oil gas such as shale gas is more and more emphasized. Under the background that the geological conditions of complex strata and the shale gas exploitation scale are continuously enlarged, the well leakage becomes one of common underground complex conditions in the development process. The lost circulation may induce downhole complex conditions such as pressure drop, borehole wall collapse, instability and the like in the well, thereby not only affecting the drilling speed, but also causing huge economic loss and having more severe requirements on drilling fluid. In addition, the lost circulation can be divided into four types, namely, porosity loss, fracture loss, karst cave loss, complex loss and the like according to the types of loss channels. The data show that the global occurrence rate of the lost circulation accounts for 20-50% of the total number of the drilled wells, wherein the malignant loss accounts for 50% of the total loss of the lost circulation, and once the malignant loss occurs, the treatment difficulty is very large, so that the serious economic loss is caused.
At present, aiming at the problem of malignant leakage, scholars at home and abroad research and develop various leakage stoppage materials, which mainly comprise polymer gel leakage stoppage materials, polymer expansion resin leakage stoppage materials, composite leakage stoppage materials and other drilling fluid leakage stoppage materials, but the various products have different functions and efficacies. However, the plugging materials mainly comprise water-based drilling fluid, and are less suitable for the oil-based drilling fluid. Compared with water-based drilling fluid, the oil-based drilling fluid has the advantages of inhibiting hydration expansion of shale, resisting high temperature, having good lubricating property, causing little damage to oil and gas reservoirs and the like. Because oil-based drilling fluids use oil as the continuous phase, they are formulated at much higher cost than water-based drilling fluids. In addition, in the process of drilling by using the oil-based drilling fluid, a malignant leakage stratum can be frequently encountered, so that a large amount of oil-based drilling fluid is leaked, and the cost of using the oil-based drilling fluid is greatly increased.
There are also patent documents on gel plugging materials suitable for oil-based drilling fluids. For example, chinese patent document CN105646763A provides an oil-based gel for use in drilling and plugging, which has good viscoelasticity and strength, and excellent plugging performance, and the gel liquid is not limited by a leakage channel before forming the gel, and easily enters pores or cracks through pressure difference and is polymerized and crosslinked in the pores and cracks to form a gel, but the gel has relatively poor gel forming controllability in complex cracks, and a preparation method thereof. Chinese patent document CN105199693A provides oil-based gel plugging slurry, which comprises the following components in parts by weight: 35-70 parts of base oil; 5-25 parts of a curing agent; 0.1-1 part of an activator; 0.5-4 parts of water; 0-60 parts of weighting agent, but the formula of the gel plugging slurry is relatively single, the gel pressure-bearing strength is insufficient, and the gel plugging slurry cannot realize effective plugging on a malignant leakage stratum. Chinese patent document CN110144198A provides a gel plugging agent for oil-based drilling fluid, which comprises the following components in parts by weight: 3 to 5 portions of oil-in-water type surfactant, 5 to 15 portions of oil, 2 to 4 portions of sodium bentonite, 8 to 12 portions of cross linker, 24 to 36 portions of gelatinizing agent, 0 to 1 portion of retarder, 5 to 15 portions of reinforcing agent, 5 to 10 portions of weighting agent and 100 portions of water. However, the gelling time of the gel is mainly adjusted by the concentration of the retarder, and in complex cracks, the initial setting time and the final setting time are difficult to grasp, and the controllability is poor, so that the leakage of the oil-based drilling fluid is easily caused.
Therefore, an oil-based gel plugging material which is suitable for the oil-based drilling fluid and has high plugging strength, temperature resistance and good controllability needs to be developed, so that the oil-based gel plugging material can be used for effectively plugging the oil-based drilling fluid loss, particularly malignant loss.
Disclosure of Invention
Aiming at the defects of the prior art, particularly the defects of poor gel forming controllability and low gel bearing strength of the existing oil-based gel plugging material in a malignant leakage stratum, the invention provides an oil-based gel consolidation plugging system for oil-based drilling fluid suitable for the malignant leakage stratum and a preparation method thereof. The oil-based gel consolidation leakage stoppage system mainly comprises oil-based gel, a temperature-sensitive curable material and oil-based cement, wherein the oil-based gel is crosslinked by using a flexible monomer and matched with a rigid monomer, so that the structural stability of the gel can be effectively improved; the curable material is lipophilic and can be combined with the oil-based gel, gradient curing is realized by matching the medium-temperature curing agent and the high-temperature curing agent, the leakage of the oil-based drilling fluid in the stratum is reduced, and the curing strength of the oil-based gel is improved; the demulsifier in the oil-based cement part is wrapped by the capsule shell and is linked with the formation leakage temperature to adjust the slow release time of the cement and form a plugging layer which takes oil-based gel as the main part and takes a curable material and oil-based cement as the auxiliary part, thereby realizing the effective plugging of the malignant leakage formation.
The technical scheme of the invention is as follows:
an oil-based gel consolidation plugging system for an oil-based drilling fluid suitable for a malignant lost circulation stratum 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.
According to the invention, 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.
Preferably, the base oil I is diesel oil or white oil; further preferably, the diesel oil is 0 # Diesel oil.
Preferably, the polymerized 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 is 1-3;
further preferably, the acrylate monomer is methyl methacrylate, glycidyl acrylate or ethylene glycol dimethacrylate; the alcohol monomer is pentaerythritol, diethylene glycol or dipropylene glycol; the rigid monomer is ethylene dibenzoate, trimethyl 1,3, 5-benzenetricarboxylate (CAS number: 2672-58-4) or methyl methylbenzoate.
Preferably, the initiator is dimethyl azobisisobutyrate, azobisisobutyronitrile or azobisisoheptonitrile.
Preferably, the gelling agent is dimethyl azelate, trioctyl trimellitate or phenyl alkylsulfonate; the alkyl benzene sulfonate is C10-18-alkyl phenyl sulfonate (CAS number: 70775-94-9).
Preferably, the crosslinking agent is trimethoxysilane, triethoxysilane, 1-triethyl-3, 3-trimethyldisiloxane or n-hexyltriethoxysilane.
Preferably, the reinforcing agent is tetraethoxysilane, methyl orthosilicate or trimethoxy silane.
Preferably, 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) And adding an initiator into the mixed solution C, and stirring for reaction to obtain the oil-based gel system.
Preferably, the stirring speed in the step (1) is 600-800r/min, and the stirring time is 15-30min.
Preferably, the stirring speed in the step (2) is 400-500r/min, and the stirring time is 10-15min.
Preferably, the stirring speed in the step (3) is 800-900r/min, and the stirring time is 20-40min.
Preferably, the initiator in the step (4) is dripped into the mixed solution C in the form of an initiator ethanol solution, and the dripping time is 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 high-performance water-based paint.
Preferably, the stirring speed in the step (4) is 400-600r/min; the reaction temperature is 90-100 ℃, and the reaction time is 3-4h.
In the oil-based gel, under the action of an initiator, ester groups in acrylate monomers and hydroxyl groups in alcohol monomers are subjected to polycondensation reaction, and long-chain acrylate molecules are linked by carbon chains of the alcohol. The hydroxyl groups on the molecular chains of the acrylate monomer and the alcohol monomer generate pairing reaction to form a coordination bond, so that the linear polymer chain is changed into a space network structure with a complex structure. In addition, a rigid monomer containing a rigid benzene ring structure is introduced to improve the stability of the structure, and simultaneously, an organic silicon reinforcing agent is also introduced, and the four valence electrons at the outermost layer of the silicon atom are combined with the polymerized monomer through covalent bonds, so that the gel has higher strength and temperature resistance.
According to the invention, the temperature-sensitive curable material system preferably 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.
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' -methylenediphenyl) bismaleimide; the weight average molecular weight of the thermosetting polyimide resin is 1500-5000, the elastic modulus is 3-4GPa, the tensile strength is more than 100MPa, and the thermal expansion coefficient is 2 multiplied by 10 -5 -3×10 -5 /° c, the dielectric constant is 3.0-3.4; the cyanate resin is bisphenol A cyanate, bisphenol F cyanate, bisphenol M cyanate 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 compound curing agent comprises 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 1-2, and more preferably 1; 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 ℃;
more preferably, the medium-temperature curing agent is beta-hydroxyethyl ethylenediamine, 2-methylimidazole or low-molecular polyamide; the low molecular polyamide is low molecular 650 type polyamide resin, the molecular weight is 600-1100, and the density is 0.97-0.99g/cm 3 The amine value is 200-240mgKOH/g, the viscosity is 1000-10000 MPa.s; the high-temperature curing agent is nadic anhydride, sebacic dihydrazide or boron trifluoride-monoethylamine complex.
According to the invention, the temperature-sensitive curable material system is prepared according to 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.
According to the invention, the medium-temperature curing agent and the high-temperature curing agent are combined to realize gradient curing, so that the consistency of gel is improved at the initial stage, a certain amount of inert materials are bonded, and the leakage loss of the leakage-stopping slurry is reduced. As the stratum temperature rises, the consistency of the plugging slurry gradually becomes larger, the high-temperature curing agent starts to participate in the polymerization reaction, and 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.
According to the invention, the oil-based cement preferably 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.
Preferably, the base oil III is the same as the base oil I.
Preferably, the curing main agent is grade G oil well cement, wherein the oil-cement ratio is 0.3.
Preferably, the wetting dispersant 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 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 more than two of polyoxyethylene polyoxypropylene octadecanol ether, polyoxyethylene polyoxypropylene polyether and AR type demulsifier; the AR type demulsifier is an oil-soluble nonionic demulsifier formed by polymerizing alkyl phenolic resin (AR resin) with polyoxyethylene and polyoxypropylene, and the HLB value is 4-8.
The microcapsule demulsifier is prepared by the following steps:
(i) Dispersing an emulsifier in dichloromethane, adding a demulsifier and an isocyanate monomer, and stirring and dispersing uniformly at a rotation speed of 1500-2000r/min to obtain an oil phase solution;
(ii) Adding polyalcohol into water, and stirring at 1500-2000r/min for 20-30min to obtain water phase solution;
(iii) Adding the water phase solution into the oil phase solution, dispersing uniformly, then adding a fluorine-containing ethylene monomer, and stirring uniformly at the rotation speed of 1000-1500r/min to obtain a monomer mixed solution;
(iv) Adding a catalyst into the monomer mixed solution, heating to 80 ℃ under the condition of stirring, and reacting for 4 hours to obtain microcapsule emulsion; then cooling to room temperature, obtaining a solid product through centrifugal separation, washing the solid product by using methanol, and then performing vacuum drying for 24 hours at 50 ℃ to obtain the microcapsule demulsifier.
Further preferably, the emulsifier in step (i) is acacia, span or tween; the span is span 20, span 40, span 60 or span 80; the tween is tween 20, tween 40, tween 60 or tween 65; the isocyanate monomer is hexamethylene diisocyanate, 2, 4-toluene diisocyanate, diphenylmethane diisocyanate or dicyclohexylmethane diisocyanate; the mass ratio of the emulsifier to the volume of the dichloromethane is 0.05-0.5g; the mass ratio of the demulsifier to the volume of the dichloromethane is 0.2-0.7g; the ratio of the mass of the isocyanate monomer to the volume of the dichloromethane is 0.1-0.6 g.
Further preferably, the polyol 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 polyhydric alcohol to the volume of water is 0.05-0.2g.
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.
Further preferably, the fluorine-containing ethylene monomer in step (iii) is tetrafluoroethylene, vinylidene fluoride or chlorotrifluoroethylene; the mass of the fluorine-containing ethylene monomer is 20-30% of the total mass of the isocyanate monomer and the polyalcohol.
Further preferably, in step (iv), the catalyst is zinc acetylacetonate, vanadic anhydride or phthalic anhydride; the addition amount of the catalyst is 3-10% of the total mass of the isocyanate monomer, the polyalcohol and the fluorine-containing ethylene monomer.
The shell of the microcapsule demulsifier is a thermoplastic polyurethane material, and is obtained by polymerizing an isocyanate group in a polyisocyanate monomer and a hydroxyl group in polyol to generate a polyurethane group, and then grafting and modifying the polyurethane group and a fluorine atom in a fluorine-containing vinyl monomer. And the fluorine atoms are easy to graft to polyurethane groups due to lower surface energy, so that the surface free energy of the polyurethane groups is reduced, and the surface hydrophobicity is improved. As the temperature of the formation increases, the wall material softens, releasing the 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 the thickness of 1-5 mu m can be formed, and if the thickness of a shell layer needs to be increased, the stirring speed can be reduced; if the thickness of the shell needs to be reduced, the stirring speed can be increased.
According to the invention, the oil-based cement is preferably prepared according to 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) And adding an inert material and a microcapsule demulsifier into the dispersion liquid E, and uniformly stirring to obtain the oil-based cement.
Preferably, the stirring speed in the step (a) 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.
According to the invention, the preparation method of the oil-based gel consolidation plugging system for the oil-based drilling fluid suitable for the malignant leakage stratum comprises the following steps:
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.
The invention has the following technical characteristics and beneficial effects:
1. the oil-based gel in the oil-based gel consolidation leakage plugging system is characterized in that an acrylate monomer and an alcohol monomer are flexibly crosslinked, and a rigid monomer containing a rigid benzene ring structure is introduced to improve the stability of a gel structure. In addition, an organic silicon reinforcing agent and a cross-linking agent are introduced into the oil-based gel, and four valence electrons at the outermost layer of a silicon atom are combined with the oil-soluble monomer through covalent bonds, so that the gel has high strength and temperature resistance, and the consolidation strength is improved by matching a temperature-sensitive curable material with the oil-based cement.
2. The temperature-sensitive curable material system in the oil-based gel consolidation leakage plugging system is formed by selecting a temperature-sensitive curable material and a compound curing agent, wherein the compound curing agent is a mixture of a medium-temperature curing agent and a high-temperature curing agent, and the medium-temperature curing agent and the high-temperature curing agent are combined to realize gradient curing, so that the gel consistency is favorably improved at the initial stage, a certain amount of inert materials are bonded, and the leakage loss of the leakage plugging slurry is reduced. Along with the rise of the formation temperature, the consistency of the plugging slurry is gradually increased, the high-temperature curing agent starts to participate in the polymerization reaction, and the curing period of the high-temperature curing agent is shortened and the strength of the gel is improved due to the action of the medium-temperature curing agent.
3. According to the oil-based cement part in the oil-based gel consolidation plugging system, the microcapsule demulsifier is used, the shell of the microcapsule demulsifier begins to soften along with the gradual rise of the temperature, the oil phase and the water phase are gradually separated under the action of the demulsifier, the oil-based cement cannot be completely replaced due to the amphiphilic performance of the surfactant, and the oil-based cement part, the microcapsule demulsifier and the water phase are mutually connected under the combined action of the medium-temperature curing agent and the high-temperature curing agent of the temperature-sensitive material; the plugging layer mainly comprising the oil-based gel and assisted by the curable material and the oil-based cement is formed, the three layers have the embedding effect, the strength of the plugging layer is improved, and the malignant leakage stratum is effectively plugged. The microcapsule demulsifier can adjust the thickness of the wall material according to the formation temperature to adjust the slow release time.
4. The oil-based gel consolidation plugging system has good gelling controllability and high gel bearing strength, and can realize effective plugging on oil-based drilling fluid loss, particularly malignant lost formations.
Drawings
FIG. 1 is a graph showing gel formation times of the oil-based gel consolidation plugging system in test example 1 at different gelling agent concentrations.
Figure 2 is a plot of gel formation strength of the oil-based gel consolidation plugging system in test example 1 at different enhancer concentrations.
Detailed Description
The present invention is further illustrated by, but not limited to, the following specific examples.
The starting materials used in the examples are, unless otherwise specified, conventional materials and commercially available, and the methods used in the examples are, unless otherwise specified, conventional techniques.
The weight average molecular weight of the thermosetting polyimide used in the examples was 5000, the elastic modulus was 3.5GPa, the tensile strength was 110MPa, and the thermal expansion coefficient was 3X 10 -5 /° C, dielectric constant of 3.4, available from Yunnan Lilian biology, inc.;
grade G oil well cement, available from Shandong Quzhou New Material science and technology Co., ltd;
polyoxyethylene polyoxypropylene stearyl ether sold by modest and chemical companies in southwest city;
the HLB value of the AR type demulsifier is about 4 to 8, and the AR type demulsifier is sold by Guangdong Shanmei environmental science and technology Limited company.
The method for testing the maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared in the embodiment comprises the following steps:
the maximum pressure-bearing plugging pressure of the prepared oil-based gel consolidation plugging system is respectively tested by adopting a simulated fracture plugging test, and the specific operation steps are as follows: opening a heating switch of the high-temperature high-pressure dynamic leaking stoppage evaluation device by using the high-temperature high-pressure dynamic leaking stoppage evaluation device, setting the formation temperature (80-150 ℃) on a temperature controller, and simulating the formation temperature condition; starting a constant flow pump, respectively injecting the prepared oil-based gel consolidation plugging systems into a core holder provided with a steel column fracture core model, and recording injection pressure in real time, wherein the total injection volume is 50 fracture core models; in the process of injecting the plugging system, the injection pressure is gradually increased, the leakage quantity of the oil-based gel consolidation plugging system is gradually reduced to 0, and the oil-based gel consolidation plugging system in the crack forms a plugging layer to plug the crack; and continuing injecting until the plugging system flows out from the outlet end of the core holder again, which shows that the plugging layer formed by the oil-based gel consolidation plugging system in the fracture is broken through, wherein the measured highest pressure value is the maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging slurry.
Example 1
An oil-based gel consolidation plugging system for an oil-based drilling fluid suitable for a malignant lost circulation stratum comprises 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 35 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, 60 parts of polymerization monomer, 1 part of initiator, 6 parts of gelling agent, 5 parts of cross-linking agent and 5 parts of reinforcing agent; base oil I is 0 # Diesel oil; the polymerized monomer is a mixture of ethylene glycol dimethacrylate, pentaerythritol and 1,3, 5-trimethyl benzenetricarboxylate, and the molar ratio of the ethylene glycol dimethacrylate, the pentaerythritol and the 1,3, 5-trimethyl benzenetricarboxylate in the mixture is 2; the initiator is dimethyl azodiisobutyrate; the gelling agent is trioctyl trimellitate; the cross-linking agent is n-hexyltriethoxysilane; the reinforcing agent is trimethoxy silane.
The temperature-sensitive curable material system comprises 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; base oil II is 0 # Diesel oil; the temperature-sensitive curing material is thermosetting polyimide; the compound curing agent comprises a medium-temperature curing agent and a high-temperature curing agent, the mass ratio of the medium-temperature curing agent to the high-temperature curing agent is 1.5, the medium-temperature curing agent is beta-hydroxyethyl ethylenediamine, and the high-temperature curing agent is sebacic dihydrazide.
The oil-based cement comprises the following raw materials in parts by mass: 35 parts of base oil III, 50 parts of curing main agent, 4 parts of wetting dispersant, 6 parts of inert material and 5 parts of microcapsule demulsifier; base oil III of 0 # Diesel oil; the curing main agent is G-grade oil well cement, and the oil-cement ratio is 0.3; the wetting dispersant is polyoxyethylene lauryl ether; the inert material is cottonseed hulls with the particle size of 20mm;
the microcapsule demulsifier is prepared by the following steps:
(i) Dispersing 5g of emulsifier Arabic gum into 50mL of dichloromethane, then adding 30g of demulsifier (mixing polyoxyethylene polyoxypropylene octadecanol ether with AR type demulsifier according to a mass ratio of 1;
(ii) Adding 10g of 1, 6-hexanediol into 100mL of water, and stirring for 30min under the condition that the rotation speed is 2000r/min to obtain an aqueous phase solution;
(iii) Adding the water phase solution into the oil phase solution, uniformly dispersing, then adding 6g of chlorotrifluoroethylene, and uniformly stirring at the room temperature and the rotating speed of 1000r/min to obtain a monomer mixed solution;
(iv) Adding 2.6g of catalyst zinc acetylacetonate into the monomer mixed solution, heating to 80 ℃ under the stirring condition of the rotating speed of 10000r/min, and reacting for 4 hours to obtain microcapsule emulsion; then cooling to room temperature, obtaining a solid product through centrifugal separation, washing the solid product by using methanol, and then performing vacuum drying for 24 hours at 50 ℃ to obtain the microcapsule demulsifier.
The preparation method of the oil-based gel consolidation plugging system suitable for the oil-based drilling fluid malignant leakage stratum comprises the following steps:
(1) Preparation of oil-based gel systems
Adding a polymerization monomer into the base oil I, stirring for 20min at the rotating speed of 700r/min, and fully dissolving to obtain a mixed solution A; mixing the gelling agent, the cross-linking agent and the reinforcing agent, stirring for 10min at the rotation speed of 500r/min, and uniformly stirring to obtain a mixed solution B; adding the mixed solution B into the mixed solution A, heating to 70 ℃, and stirring and mixing for 30min under the condition that the rotating speed is 800r/min to obtain a mixed solution C; adding an initiator into absolute ethyl alcohol, and stirring for 15min under the condition that the rotating speed is 1000r/min to obtain an initiator ethanol solution with the concentration of 0.1 g/mL; dropwise adding the initiator ethanol solution into the mixed solution C for 2min; then reacting for 4 hours under the conditions that the stirring speed is 500r/min and the temperature is 95 ℃ to obtain the oil-based gel system.
(2) Preparation of temperature-sensitive curable material system
And adding the temperature-sensitive curable material and the compound curing agent into the base oil II, and stirring for 15min at the speed of 2000r/min to obtain a temperature-sensitive curable material system.
(3) Preparation of oil-based cements
Dispersing the wetting dispersant in the base oil III, stirring for 10min at the rotation speed of 4000r/min, and uniformly stirring to obtain a dispersion liquid D; adding the curing main agent into the dispersion liquid D, stirring for 30min at the rotating speed of 12000r/min, and uniformly stirring to obtain a dispersion liquid E; and adding an inert material and a microcapsule demulsifier into the dispersion liquid E, stirring for 10min at the rotation speed of 4000r/min, and uniformly stirring to obtain the oil-based cement.
(4) Preparation of oil-based gel consolidation plugging system
And adding the oil-based cement and the temperature-sensitive curable material system into the oil-based gel system, and stirring for 20min at the rotating speed of 2000r/min by using a high-speed stirrer to obtain the oil-based gel.
The oil-based gel consolidation plugging system prepared by the embodiment is subjected to a maximum pressure-bearing plugging pressure test under the following specific test conditions: and (3) testing a: the loss rate is 50m 3 H, the temperature is 100 ℃; and b, testing: the loss velocity is 60m 3 H, the temperature is 110 ℃; and c, testing: the loss rate was 70m 3 H, the temperature is 120 ℃; and (4) testing d: the loss rate was 80m 3 The temperature is 130 ℃, the leak-off speed in the test is the leak-off speed of the fracture core model, and the change of the injection pressure along with the time and the maximum pressure-bearing plugging pressure in the test process are shown in table 1.
TABLE 1
As can be seen from Table 1, the leak-off speed was 50m 3 At the temperature of 100 ℃, the initial plugging pressure is 3.7MPa at 1h, the maximum plugging pressure reaches 8.2MPa at 4h, and the plugging layer is damaged at 5h, and the pressure gradually decreases to 5.3MPa. At a loss velocity of 60m 3 At the temperature of 110 ℃, the initial plugging pressure is 3.6MPa at 1h, the maximum plugging pressure is 8.3MPa at 4h, the plugging layer is damaged at 5h, the pressure gradually drops to 5.3MPa, and in the initial stage of the injection stage of the test b, because cracks are increased, the temperature change is small, the plugging strength is slightly lower under the condition that the proportion of the curing agent is not adjusted compared with that in the same period of the test a, and the plugging strength reaches the maximum after 4h. At a loss rate of 70m 3 At the temperature of 120 ℃, the initial plugging pressure is 3.7MPa at 1h, the maximum plugging pressure reaches 8.5MPa at 4h, the plugging layer is damaged at 5h, the pressure is gradually reduced to 5.6MPa, and the leakage speed is 70m 3 And h, because the temperature is increased, the solidification of the gel consolidation plugging system is advanced compared with the test b, and therefore the plugging strength is slightly higher than the test b. At a loss rate of 80m 3 H, at the temperature of 130 ℃, the initial plugging pressure is 2.0MPa at 1h, the plugging pressure reaches the maximum value of 8.6MPa at 4h, the plugging layer is damaged at 5h, the pressure gradually drops to 5.8MPa, and the test d is that in the initial plugging stage, due to crack increase, even if the solidification effect is advanced due to temperature rise, but an effective plugging is not formed in the oil-based gel consolidation system, the plugging pressure in the initial plugging stage is lower, then the plugging pressure is gradually increased, and due to higher temperature, the plugging pressure is lowerAnd the plugging pressure in the subsequent stage rises faster and reaches the maximum value in 4 hours, which shows that the plugging of the oil-based gel consolidation plugging system is successful, and then the plugging layer gradually fails along with the gradual increase of the pressure. In addition, as can be seen from table 1, the gel consolidation plugging system of the embodiment has stronger plugging strength for fractures at different temperatures and at different leakage rates, and can realize effective plugging of a malignant leakage stratum.
Example 2
An oil-based gel consolidation lost circulation system for oil-based drilling fluids suitable for use in a malignant lost circulation formation, as described in example 1, except that: the molar ratio of ethylene glycol dimethacrylate, pentaerythritol, and trimethyl 1,3, 5-benzenetricarboxylate is 1.
The preparation method of the oil-based gel consolidation plugging system for the oil-based drilling fluid suitable for the malignant lost circulation stratum is described in example 1.
The oil-based gel consolidation plugging system prepared by the embodiment is subjected to a maximum pressure-bearing plugging pressure test under the following specific test conditions: and (3) testing a: the loss rate is 50m 3 H, the temperature is 100 ℃; and b, testing: the loss rate is 60m 3 H, the temperature is 110 ℃; and c, testing: the loss velocity was 70m 3 H, the temperature is 120 ℃; and (3) testing d: the loss velocity was 80m 3 The temperature is 130 ℃, and the change of the injection pressure along with the time and the maximum pressure-bearing plugging pressure in the test process are shown in the table 2.
TABLE 2
The molar ratio of ethylene glycol dimethacrylate, pentaerythritol, and trimethyl 1,3, 5-benzenetricarboxylate in this example was 1, and the performance was slightly inferior to that of example 1, mainly because ethylene glycol dimethacrylate mainly assumes the flexible part in the oil-based gel system, and when the amount of ethylene glycol dimethacrylate was small, the strength of the polymerized product forming a cross-linked structure was inferior to that of example 1, macroscopically expressed as gel strength and the maximum plugging pressure was slightly lower than that of example 1.
Example 3
An oil-based gel consolidation lost circulation system for oil-based drilling fluids suitable for use in malignant lost circulation formations is as described in example 1, except that: the molar ratio of ethylene glycol dimethacrylate, pentaerythritol, and trimethyl 1,3, 5-benzenetricarboxylate was 3.
The preparation method of the oil-based gel consolidation plugging system for the oil-based drilling fluid suitable for the malignant lost circulation stratum is described in example 1.
The oil-based gel consolidation plugging system prepared by the embodiment is subjected to a maximum pressure-bearing plugging pressure test under the following specific test conditions: and (3) testing a: the loss rate is 50m 3 H, the temperature is 100 ℃; and b, testing: the loss velocity is 60m 3 H, the temperature is 110 ℃; and c, testing: the loss rate was 70m 3 H, the temperature is 120 ℃; and (3) testing d: the loss rate was 80m 3 The temperature was 130 ℃ and the injection pressure change with time and the maximum pressure plugging pressure during the test are shown in Table 3.
TABLE 3
In the embodiment, the molar ratio of the ethylene glycol dimethacrylate to the pentaerythritol to the trimethyl 1,3, 5-benzenetricarboxylate is 3. However, with the continuous increase of the concentration of the ethylene glycol dimethacrylate in the system, the proportion of the flexible part is too high, the crosslinking density of the gel system is high, the flexibility of the chain is reduced, the crosslinking stability of the system is continuously reduced, the macroscopic expression shows that the gel strength is insufficient, and the maximum plugging pressure is reduced. Therefore, the proportion of the ethylene glycol dimethacrylate in the embodiment is slightly higher than that in the embodiment 1, and the gel strength and the maximum plugging pressure of the obtained oil-based gel consolidation plugging system are slightly lower than those in the embodiment 1.
Example 4
An oil-based gel consolidation lost circulation system for oil-based drilling fluids suitable for use in a malignant lost circulation formation, as described in example 1, except that: 40 parts of an oil-based gel system, 20 parts of a temperature-sensitive curable material system and 40 parts of oil-based cement.
The preparation method of the oil-based gel consolidation plugging system for the oil-based drilling fluid suitable for the malignant lost circulation stratum is described in example 1.
The oil-based gel consolidation plugging system prepared by the embodiment is subjected to a maximum pressure-bearing plugging pressure test under the following specific test conditions: and (3) testing a: the loss velocity was 50m 3 H, the temperature is 100 ℃; and (b) testing: the loss rate is 60m 3 H, the temperature is 110 ℃; and (c) testing: the loss rate was 70m 3 H, the temperature is 120 ℃; and (3) testing d: the loss velocity was 80m 3 The temperature was 130 ℃ and the injection pressure change with time and the maximum pressure plugging pressure during the test are shown in Table 4.
TABLE 4
The oil-based gel consolidation lost circulation system of this example performed slightly worse than the oil-based gel system of example 1. This is mainly due to the fact that the curable material increases in adhesion at the beginning of the curing stage, before the oil-based gel does not form a plugging layer, resulting in a slight increase in the overall plugging pressure compared to the original composition. After the oil-based gel is gradually gelled, the maximum plugging capacity of the plugging layer is slightly reduced due to the slight reduction of the part of the oil-based gel.
Comparative example 1
An oil-based gel consolidation lost circulation system as described in example 1, except that: and oil-based cement is not added into the oil-based gel consolidation plugging system.
At a loss velocity of 50m 3 H, the maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the maximum pressure-bearing plugging pressure isThe results are shown in Table 5 below.
TABLE 5
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 1.7 | 2.4 | 2.7 | 3.5 | 1.2 |
As can be seen from table 5, in the comparative example, no oil-based cement is added, the plugging pressure of the obtained oil-based gel consolidation plugging system in each time period is lower than that in the example 1 of the present invention, and when no oil-based cement is added, the oil-based gel consolidation plugging system lacks the curing effect of the oil-based cement, so that the overall strength of the consolidation plugging system is greatly reduced.
Comparative example 2
An oil-based gel consolidation lost circulation system as described in example 1, except that: the temperature-sensitive curing material is not added in the temperature-sensitive curable material system.
At a loss rate of 50m 3 The temperature is 100 ℃, and the test book isThe maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is shown in the following table 6.
TABLE 6
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 1.9 | 2.7 | 4.2 | 4.7 | 2.3 |
As can be seen from table 6, in the comparative example, no temperature-sensitive curing material is added, the plugging pressure of the obtained oil-based gel consolidation plugging system in each time period is lower than that in the example 1 of the present invention, mainly because the oil-based gel consolidation plugging system is lack of the temperature-sensitive curing material, the consistency of the oil-based gel consolidation plugging system is reduced, and compared with the case of adding the temperature-sensitive curing material, the leakage amount of the oil-based gel consolidation plugging system is increased, and the plugging pressure is reduced.
Comparative example 3
An oil-based gel consolidation lost circulation system is as described in example 1, except that: and no compound curing agent is added to the temperature-sensitive curable material part in the oil-based gel consolidation plugging system.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 7.
TABLE 7
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.1 | 3.5 | 4.6 | 5.7 | 3.5 |
As can be seen from Table 7, the leak-off speed was 50m 3 And h, under the same condition that the temperature is 100 ℃, the pressure-bearing plugging pressure of the oil-based gel consolidation plugging system is lower in the initial stage, the plugging pressure reaches the maximum value after 4 hours of injection, and the plugging layer is gradually damaged and destabilized along with the increase of the injection amount. Due to the lack of the compound curing agent, gradient curing cannot be realized in an oil-based gel consolidation plugging system, and the temperature sensitivity is improved by depending on the formation temperatureThe consistency of the curing material is weaker in pressure-bearing plugging capability in the initial stage compared with a system added with a curing agent; and the pressure-bearing plugging capability of the whole stage is also inferior to that of the embodiment 1 of the invention.
Comparative example 4
An oil-based gel consolidation plugging system is described in example 1, wherein the polymerized monomers of the oil-based gel are pentaerythritol and trimethyl 1,3, 5-benzenetricarboxylate (mass ratio of 1.
At a loss velocity of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 8.
TABLE 8
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.4 | 3.3 | 4.3 | 5.0 | 3.4 |
As can be seen from Table 8, in this comparative example, no acrylate monomer was added, and the performance of the resulting oil-based gel consolidation system was inferior to that of inventive example 1. The ethylene glycol dimethacrylate mainly bears a flexible part in an oil-based gel system, when the ethylene glycol dimethacrylate is not added, a polymerization product cannot form an effective cross-linking structure, the intention of the cross-linking structure cannot be completely realized, and the macroscopic expression 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 described in example 1, wherein the polymerized monomers in the oil-based gel are ethylene glycol dimethacrylate and 1,3, 5-trimethyl benzenetricarboxylate (mass ratio of 2.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 9.
TABLE 9
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.3 | 3.1 | 3.8 | 4.5 | 3.2 |
As can be seen from Table 9, in this comparative example, no alcohol monomer was added, and the performance of the resulting oil-based gel consolidation system was inferior to that of inventive example 1. The main reason is that when no alcohol monomer is added, the polymerization product can not form an effective cross-linked space network structure, so that 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 described in example 1, wherein the polymerized monomers of the oil-based gel are ethylene glycol dimethacrylate, pentaerythritol (mass ratio of 2.
At a loss velocity of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared in the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 10.
TABLE 10
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.5 | 3.5 | 4.4 | 5.2 | 3.5 |
As can be seen from Table 10, in this comparative example, no rigid monomer was added, and the resulting oil-based gel consolidation system was inferior in performance to example 1 of the present invention. The main reason is that the 1,3, 5-trimethyl benzenetricarboxylate bears the rigid part in the gel system, and the stability of the gel system is enhanced and the strength is increased after gelling due to the introduction of a proper amount of rigid units. However, no rigid monomer is added, the concentration of the ethylene glycol dimethacrylate in the system is increased, the crosslinking density of the gel system is high, the chain elasticity is reduced, and the crosslinking stability of the system is continuously reduced, so that the gel strength of the obtained oil-based gel consolidation system is insufficient, and the maximum plugging pressure is low.
Comparative example 7
An oil-based gel consolidation lost circulation system is described in example 1, wherein the polymerized monomers of the oil-based gel are butyl acrylate, pentaerythritol, and trimethyl 1,3, 5-benzenetricarboxylate.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared in the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 11.
TABLE 11
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.8 | 3.7 | 5.0 | 5.5 | 3.2 |
As can be seen from Table 11, the use of butyl acrylate as the acrylate monomer in this comparative example results in a poorer performance oil-based gel consolidation system than example 1 of the present invention. The acrylic ester monomer is characterized in that under the action of an initiator, a long chain acrylic ester molecular chain is combined more tightly by a carbon chain, and the crosslinking stability of the system is improved. Therefore, the oil-based gel consolidation system obtained by adding butyl acrylate in the comparative example has insufficient gel strength, and the maximum plugging pressure is reduced.
Comparative example 8
An oil-based gel consolidation lost circulation system is described in example 1, wherein the polymerized monomers in the oil-based gel are ethylene glycol dimethacrylate, pentaerythritol, and styrene.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 12.
TABLE 12
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 2.9 | 4.2 | 5.2 | 5.7 | 3.3 |
As can be seen from Table 12, in this comparative example using styrene as the rigid monomer, the resulting oil-based gel consolidation system had inferior performance to example 1 of the present invention. This is because vinyl electrons in styrene are conjugated with benzene rings, and monomer radicals of styrene monomers have only one hydrogen bond acceptor to undergo polymerization reaction during polymerization, which results in less polymerization sites and reduced crosslinking stability of the system, as compared with trimethyl 1,3, 5-benzenetricarboxylate. In addition, styrene as a rigid monomer bears the skeleton structure in the gel system, the compactness of the rigid monomer in a spatial network structure directly determines the overall strength of the gel, and the 1,3, 5-trimethyl benzenetricarboxylate is more compact in the cross-linking process for constructing a main chain. Therefore, the oil-based gel consolidation system obtained by adding styrene in the comparative example has insufficient gel strength, and the maximum plugging pressure is reduced.
Comparative example 9
An oil-based gel consolidation lost circulation system as described in example 1, except that: the enhancer is DH-1 enhancer.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared in the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 13.
Watch 13
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 3.2 | 4.7 | 6.3 | 7.1 | 4.0 |
As can be seen from Table 13, in this comparative example, where DH-1 reinforcing agent was used instead of the silicone-based reinforcing agent of the present invention, the performance of the resulting oil-based gel consolidation system was inferior to that of example 1 of the present invention. The reinforcing agent used in the invention is an organic silicon reinforcing agent, and the four valence electrons at the outermost layer of silicon atoms are combined with the covalent bonds between the polymerized monomers, so that the gel has higher strength and temperature resistance. The reinforcing agent used in comparative example 9 did not have the above-mentioned effect, and therefore, the performance of the resulting oil-based gel consolidation system was inferior to that of example 1 of the present invention.
Comparative example 10
An oil-based gel consolidation lost circulation system as described in example 1, except that: the mass ratio of the medium-temperature curing agent to the high-temperature curing agent in the compound curing agent is 2.
At a loss rate of 50m 3 The maximum pressure-bearing plugging pressure of the oil-based gel consolidation plugging system prepared by the comparative example is tested at the temperature of 100 ℃, and the results are shown in the following table 14.
TABLE 14
| Time/ |
1 | 2 | 3 | 4 | 5 |
| Plugging pressure/MPa | 3.9 | 5.4 | 6.5 | 7.7 | 4.3 |
In the comparative example, the proportion of the medium-temperature curing agent and the high-temperature curing agent is changed, the maximum pressure-bearing plugging pressure of the obtained oil-based gel consolidation plugging system is slightly worse than that of the oil-based gel consolidation plugging system in the embodiment 1 of the invention, which shows that the proportion of the medium-temperature curing agent and the high-temperature curing agent has certain influence on the plugging strength of the oil-based gel consolidation plugging system, and the proportion needs to be controlled within the range of the invention.
Test example 1
And (3) gelling time: the construction time is an important factor for ensuring the underground safety, but the temperature gradients of different stratums are different, and construction leakage points of different stratums and different wells in the same stratum are possibly different, so that the temperature difference is caused. Therefore, the invention regulates and controls the gelling time of the oil-based gel system by regulating the proportion of the gelling agent in the oil-based gel system so as to regulate and control the gelling time of the whole plugging system.
The specific conditions were as described in example 1, except that the gelling agents were added in amounts of 5 parts, 6 parts, 7 parts, 8 parts, 9 parts and 10 parts, respectively, and the remaining components were not added to adjust the gelling time of the chemical gel. The results are shown in FIG. 1.
As can be seen from fig. 1, the gelling time of the oil-based gel gradually decreases with increasing addition of the gelling agent in the oil-based gel system, and when the addition of the gelling agent is 5 parts, the gelling time of the oil-based gel is the longest, and reaches 4.7h. When the addition amount of the gelling agent is 10 parts, the gelling time of the oil-based gel is shortest, and the gelling time is up to 3.2h. Along with the gradual increase of the addition of the gelling agent, the number of active groups participating in the crosslinking reaction is continuously increased, the interaction probability among the reactive groups is continuously increased, the speed of forming a network mechanism by a gel system is continuously increased, and the gelling time is continuously reduced. The gelling agent is added in an amount of between 6 and 7 parts based on the time of field application.
And (3) gel forming strength: in order to effectively block a leakage stratum, a high-temperature high-pressure displacement device is used for testing the gelling strength of the oil-based gel consolidation plugging system under the condition that the leakage speed is 50m 3 The temperature is 100 ℃, wherein the maximum pressure-bearing plugging pressure is the gel forming strength; according to the invention, the gelling strength of the oil-based gel in the oil-based gel consolidation plugging system is regulated and controlled by regulating and controlling the addition amount of the reinforcing agent.
The specific conditions were as described in example 1, except that the addition amounts of the reinforcing agent were changed to 1 part, 2 parts, 3 parts, 4 parts, 5 parts and 6 parts, respectively, and the addition amounts of the remaining components were not changed to adjust the gel strength of the chemical gel. The results are shown in FIG. 2.
As can be seen from fig. 2, as the proportion of the reinforcing agent in the oil-based gel system is increased, the gel-forming strength of the oil-based gel is slightly decreased after being gradually increased, and when the reinforcing agent is added at 1 part, the strength of the oil-based gel is the lowest and 6.1MPa, and when the reinforcing agent is added at 5 parts, the strength of the oil-based gel is the highest and 8.2MPa. Along with the gradual increase of the proportion of the reinforcing agent in the gel system, the dispersibility of the gel system is gradually improved, the fluidity of the gel system is gradually reduced, the interior of the gel system is gradually and tightly connected to gradually achieve good mechanical strength, and when the adding amount of the reinforcing agent is 5 parts, the strength of the oil-based gel is the maximum.
In addition, the invention combines the medium-temperature curing agent and the high-temperature curing agent to realize the gradient curing, is beneficial to improving the consistency of the gel at the initial stage, and is bonded with a certain amount of inert materials to reduce the leakage of a gel system. The ratio of the medium-temperature curing agent to the high-temperature curing agent can be adjusted to adjust the consistency.
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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| CN116515074B (en) * | 2022-04-25 | 2024-04-30 | 江苏奥斯佳材料科技股份有限公司 | Polyurethane dispersion, preparation method thereof and polyurethane adhesive |
| CN114907826B (en) * | 2022-05-28 | 2023-08-11 | 西安石油大学 | Targeting deep profile control agent and preparation method and application thereof |
| CN115261000B (en) * | 2022-07-14 | 2024-01-19 | 中国石油大学(华东) | Emulsifier for super-high temperature resistant oil-based drilling fluid and preparation method and application thereof |
| CN115538972B (en) * | 2022-09-21 | 2023-08-29 | 新疆格瑞迪斯石油技术股份有限公司 | Drilling plugging method suitable for malignant leakage stratum |
| CN116284607B (en) * | 2023-03-24 | 2024-06-25 | 中国石油大学(华东) | Water-soluble controllable curing resin plugging agent and preparation method and application thereof |
| CN116536035B (en) * | 2023-04-04 | 2024-06-07 | 中国石油大学(华东) | Controllable cured resin plugging system suitable for malignant lost circulation stratum and preparation method and application thereof |
| CN116396732A (en) * | 2023-05-29 | 2023-07-07 | 中石化西南石油工程有限公司 | Temperature-sensitive consolidation plugging agent and preparation method thereof |
| CN117534967B (en) * | 2024-01-08 | 2024-03-22 | 克拉玛依市义恩技术服务有限责任公司 | Cationic emulsified asphalt for drilling fluid and preparation method thereof |
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Inventor after: Lv Kaihe Inventor after: Ran Qihua Inventor after: Zhao Li Inventor after: Yao Rugang Inventor after: Dai Liyao Inventor after: Bai Yingrui Inventor after: Sun Jinsheng Inventor after: Liu Fengbao Inventor after: Li Shuanggui Inventor after: Zhang Xianbin Inventor after: Cao Lihu Inventor after: Fang Junwei Inventor before: Lv Kaihe Inventor before: Fang Junwei Inventor before: Ran Qihua Inventor before: Zhao Li Inventor before: Yao Rugang Inventor before: Dai Liyao Inventor before: Bai Yingrui Inventor before: Sun Jinsheng Inventor before: Li Gongrang Inventor before: Liu Fengbao Inventor before: Li Shuanggui Inventor before: Zhang Xianbin Inventor before: Cao Lihu |