High-strength shear response type gel for well drilling leakage stoppage and preparation method of high-strength shear response type gel

Abstract

The invention relates to a high-strength shear response type gel for well drilling plugging, which is prepared from the following raw materials in parts by weight: 100 parts of deionized water, 18-21 parts of nonionic monomer, 5-6 parts of rheology regulating agent, 2-3 parts of nonionic surfactant, 1-1.5 parts of organic polymer cross-linking agent, 1-1.5 parts of flexible fiber and 0.2-0.3 part of initiator. The invention further discloses a preparation method of the high-strength shear response type gel for well drilling leakage stoppage. The high-strength shear response type gel for well drilling leaking stoppage has the shear response properties of shear dilution and standing thickening, the viscosity is low in the injection process, the gel is easily injected into a stratum leakage channel, after injection is completed, the viscosity is rapidly increased in the leakage channel, the gel is easily retained and reacts to form gel under the stratum environment condition, a high-strength plugging layer is formed, and the high-strength plugging layer is used for well drilling leaking stoppage. A leakage channel is blocked, and continuous leakage of drilling fluid is prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of oil drilling plugging agents, and in particular relates to a high-strength shear response gel used for drilling plugging and a preparation method thereof. Background Art

[0002] The loose loess of the Quaternary system of the Cenozoic Era in Yan'an is prone to leakage, and the formation is loosely cemented. It is difficult for the drilling fluid to carry cuttings and maintain the stability of the well wall. The formation joints, microcracks, and microfissures are well developed, and the brittleness is high. When the formation is opened by drilling, the pressure is released, resulting in pressure imbalance. In addition, external fluids (such as filtrate) penetrate along the cracks, producing hydraulic splitting, which can easily lead to formation fragmentation, induce well wall instability, cause drill sticking, well collapse and other underground complex situations, prolong drilling time, consume mud, and cause unnecessary economic losses. For malignant leakage formations with macroscopic large cracks, it is necessary to use plugging materials with high strength, viscoelasticity, weak gravity sedimentation, easy to achieve effective filling of longitudinal cracks, and a continuous phase after solidification that is not easily dispersed by pressure difference fluctuations. The high-strength shear-responsive gel has the shear-responsive properties of "shear thinning and static thickening". During the injection process, the viscosity is low and it is easy to be injected into the formation leakage channel. After the injection is completed, the viscosity in the leakage channel rapidly thickens and is easy to stay. It reacts into gel under the formation environment conditions to form a high-strength plugging layer, plugging the leakage channel and preventing the drilling fluid from continuing to leak. The gel plugging material introduces a synthetic non-ionic surfactant PTB. Compared with the traditional gel that directly uses non-ionic surfactants, it can enhance the stability of the system and thus improve the overall uniformity of the gel. The gel body generated after curing into gel has higher strength and stronger toughness, which enables the gel to form a denser and firmer plugging structure when dealing with complex leakage formations, effectively enhancing the plugging effect. Compared with traditional high-molecular polymer gels, the gravity sedimentation effect of the gel plugging agent before curing into gel is weaker, and the migration front edge in the large fracture leakage space is uniform, which can completely displace the formation fluid in the leakage channel and then completely fill the leakage channel. Compared with traditional high molecular polymer gel, the gel plugging agent has good shear resistance before solidification, and the injection rate has no effect on its performance after solidification. The gel plugging agent has good resistance to formation fluid dilution. Summary of the invention

[0003] The invention provides a high-strength shear-responsive gel for drilling plugging and a preparation method thereof. The high-strength shear-responsive gel has the shear response properties of "shear thinning and static thickening". During the injection process, the viscosity is low and it is easy to be injected into the formation leakage channel. After the injection is completed, the viscosity thickens rapidly in the leakage channel and it is easy to stay. It reacts into gel under formation environmental conditions to form a high-strength plugging layer, plugging the leakage channel and preventing the drilling fluid from continuing to leak.

[0004] A high-strength shear-responsive gel for plugging leaks in drilling, comprising the following raw materials in parts by weight: 100 parts of deionized water, 18-21 parts of nonionic monomers, 5-6 parts of rheology control agents, 2-3 parts of nonionic surfactants, 1-1.5 parts of organic polymer crosslinking agents, 1-1.5 parts of flexible fibers, and 0.2-0.3 parts of initiators; The nonionic surfactant is a synthetic nonionic surfactant PTB, which is prepared according to the following method, the specific steps are: (1) 1,12-diaminododecane and cyclobut-3-enedicarboxylic anhydride are mixed in a mass ratio of 1.05:1, placed in a container, and deoxygenated by passing nitrogen for 20 minutes. The mixture is reacted at 150-200°C for 3-4 hours to undergo a nucleophilic addition-elimination reaction to generate an imide. (2) The imide obtained in step (1) is rapidly cooled to room temperature, and one-half of the cooled imide is taken, and the imide and the polyol are placed in a container and mixed at a mass ratio of 1:2.5, and anhydrous xylene is added. The oil bath is heated to 60-70° C. while stirring at a speed of 300-500 rpm, until the polyol is completely dissolved to form a uniform transparent solution; (3) Add the remaining half of the cooled imide of step (2) dropwise to the transparent solution obtained in step (2) while continuing to stir, control the reaction temperature to 70-80° C., and react for 2-3 h. After the reaction is complete, a mixture is obtained, and the mixture is cooled to room temperature in a nitrogen stream, purified, and vacuum dried to obtain a synthetic nonionic surfactant PTB.

[0005] Preferably, the vacuum drying temperature in step (3) is 50° C., and the time is 12 to 24 h; and the dripping speed is 1 to 2 drops / second.

[0006] Preferably, the nonionic monomer is one or more of acrylamide, N-isopropylacrylamide and N-vinylpyrrolidone.

[0007] Preferably, the rheology control agent is one or both of nano-silicon dioxide and nano-calcium carbonate.

[0008] Preferably, the organic polymer crosslinking agent is an organic boron crosslinking agent.

[0009] Preferably, the flexible fiber is one or both of polyester fiber and polypropylene fiber.

[0010] Preferably, the initiator is ammonium persulfate, potassium persulfate or sodium bisulfite.

[0011] A method for preparing the high-strength shear-responsive gel for drilling plugging as claimed in claim 1, comprising the following steps: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) adding an organic polymer cross-linking agent to solution A to obtain solution B, stirring the solution at room temperature and 500 rpm for 8-10 min, transferring the solution to a 60°C water bath, deoxygenating the solution with nitrogen for 20 min, then sequentially adding a nonionic surfactant, a flexible fiber, and a rheology control agent, stirring the solution at room temperature and 200 rpm for 30-50 min to obtain a mixed solution; (3) The initiator is added to 5 parts of deionized water, and then added dropwise to the mixed solution obtained in step (2) under stirring, and the stirring is continued for 30 minutes. The mixture is allowed to react to obtain a high-strength shear-responsive gel for drilling plugging.

[0012] Preferably, the nitrogen flow rate of the nitrogen deoxygenation in step (2) is 1-2 L / min.

[0013] Preferably, the temperature of the static reaction in step (3) is 20-30°C and the time is 6-8 hours; the dripping speed in step (3) is 2-4 seconds / drop.

[0014] Advantages of the present invention (1) The present invention provides a high-strength shear-responsive gel, which has the shear-responsive properties of "shear thinning and static thickening". During the injection process, the viscosity is low and it is easy to be injected into the formation loss channel. After the injection is completed, the viscosity in the loss channel rapidly thickens and is easy to stay. Under the formation environment conditions, it reacts to form a gel to form a high-strength plugging layer, plugging the loss channel and preventing the drilling fluid from continuing to leak; (2) After the high-strength shear-responsive gel is cured, the generated gel has higher strength and toughness, and has a better plugging effect on the leakage channel. When the injection volume is 0.8 pv, the plugging strength of the shear-responsive gel can reach about 6.5 MPa; (3) The high-intensity shear-responsive gel has the shear thixotropic properties of "shear thinning and static thickening". When the shear rate is close to zero, the apparent viscosity of the gel rises sharply and shows a cliff-like increase, up to 10 6 MPa•s; when the shear rate gradually increases, the apparent viscosity of the gel tends to decrease as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the relationship between viscosity and shear rate in Example 3.

[0016] Figure 2 This is the relationship between the gel injection volume and the water flooding breakthrough pressure in Example 3.

[0017] Figure 3 This is the relationship between viscosity and shear rate of Example 4.

[0018] Figure 4 This is the relationship between the gel injection volume and the water flooding breakthrough pressure in Example 4.

[0019] Figure 5 The relationship between the injection volume and the water flooding breakthrough pressure of the gel plugging agent prepared in Example 3 and Comparative Example 1. DETAILED DESCRIPTION

[0020] Example 1 A synthetic nonionic surfactant PTB is prepared according to the following method, the specific steps are: (1) 1,12-diaminododecane and cyclobut-3-enedicarboxylic anhydride were mixed in a mass ratio of 1.05:1, placed in a container, and deoxygenated by passing nitrogen for 20 minutes. The mixture was reacted at 150°C for 4 hours to undergo a nucleophilic addition-elimination reaction to generate an imide. (2) The imide obtained in step (1) is rapidly cooled to room temperature, and one-half of the cooled imide is taken, and the imide and the polyol are placed in a container and mixed at a mass ratio of 1:2.5, and anhydrous xylene is added. The oil bath is heated to 70° C. while stirring at 300 rpm until the polyol is completely dissolved to form a uniform transparent solution; (3) To the transparent solution obtained in step (2), slowly add 2 drops per 1 / 2 of the cooled imide obtained in step (2) at a dropping rate of 2 drops per 1 / 2 while continuing to stir, control the reaction temperature to 70°C, and the reaction time to 3 h. After the reaction is complete, a mixture is obtained. The mixture is cooled to room temperature in a nitrogen stream, purified, and vacuum dried at 50°C for 12 h to obtain a synthetic nonionic surfactant PTB.

[0021] Example 2 A synthetic nonionic surfactant PTB is prepared according to the following method, the specific steps are: (1) 1,12-diaminododecane and cyclobut-3-enedicarboxylic anhydride were mixed in a mass ratio of 1.05:1, placed in a container, and deoxygenated by nitrogen flow for 20 minutes. The mixture was reacted at 200°C for 3 hours to undergo a nucleophilic addition-elimination reaction to generate an imide. (2) The imide obtained in step (1) is rapidly cooled to room temperature, and one-half of the cooled imide is taken, and the imide and the polyol are placed in a container and mixed at a mass ratio of 1:2.5, and anhydrous xylene is added. The oil bath is heated to 60° C. while stirring at a speed of 500 rpm until the polyol is completely dissolved to form a uniform transparent solution; (3) Add the remaining half of the cooled imide obtained in step (2) to the transparent solution obtained in step (2) at a controlled dropping rate of 1 drop per 1 minute while continuing to stir, control the reaction temperature to 80° C., and the reaction time to 2 h. After the reaction is complete, a mixture is obtained, and the mixture is cooled to room temperature in a nitrogen stream, purified, and vacuum dried at 50° C. for 24 h to obtain a synthetic nonionic surfactant PTB.

[0022] Example 3 A high-strength shear-responsive gel for plugging leaks in drilling, comprising the following raw materials in parts by weight: 100 parts of deionized water, 19.5 parts of nonionic monomers, 5 parts of rheology control agents, 2.5 parts of nonionic surfactants, 1.2 parts of organic polymer crosslinking agents, 1.2 parts of flexible fibers, and 0.2 parts of initiators; The nonionic monomer is acrylamide; The rheology control agent is nano silicon dioxide; The organic polymer cross-linking agent is an organic boron cross-linking agent; The flexible fiber is polyester fiber; The initiator is ammonium persulfate; The nonionic surfactant is prepared according to the method of Example 2.

[0023] A method for preparing a high-strength shear-responsive gel for drilling plugging, comprising the following steps: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) Add the organic polymer cross-linking agent to solution A to obtain solution B, stir at room temperature and 500 rpm for 10 min, transfer to a 60°C water bath, deoxygenate with nitrogen at a flow rate of 1 L / min for 20 min, then add nonionic surfactant, flexible fiber, and rheology control agent in sequence, stir at room temperature and 200 rpm for 50 min to obtain a mixed solution; (3) Add the initiator to 5 parts of deionized water, and then slowly add it to the mixed solution obtained in step (2) at a dropping rate of 4 drops per second under stirring, continue stirring for 30 minutes, and let it stand at 25°C for 8 hours to obtain a high-strength shear-responsive gel for drilling plugging.

[0024] Example 4 A high-strength shear-responsive gel for plugging leaks in drilling, comprising the following raw materials in parts by weight: 100 parts of deionized water, 18.5 parts of nonionic monomers, 5 parts of rheology control agents, 2 parts of nonionic surfactants, 1.2 parts of organic polymer crosslinking agents, 1.4 parts of flexible fibers, and 0.2 parts of initiators; The nonionic monomer is N-isopropylacrylamide; The rheology control agent is nano calcium carbonate; The flexible fiber is polypropylene fiber; The initiator is potassium persulfate; The rest is the same as in Example 3.

[0025] A method for preparing a high-strength shear-responsive gel for drilling plugging, comprising the following steps: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) Adding an organic polymer crosslinking agent to solution A to obtain solution B, stirring the mixture at room temperature and 500 rpm for 10 min, transferring the mixture to a 60°C water bath, deoxygenating the mixture with nitrogen at a flow rate of 1.5 L / min for 20 min, and then sequentially adding a nonionic surfactant, a flexible fiber, and a rheology control agent, stirring the mixture at room temperature and 200 rpm for 40 min to obtain a mixed solution; (3) Add the initiator to 5 parts of deionized water, and then slowly add it to the mixed solution obtained in step (2) at a dropping speed of 2 drops per second under stirring, continue stirring for 30 minutes, and let it stand at 25°C for 7 hours to obtain a high-strength shear-responsive gel for drilling plugging.

[0026] Example 5 A high-strength shear-responsive gel for plugging leaks in drilling, comprising the following raw materials in parts by weight: 100 parts of deionized water, 21 parts of nonionic monomers, 6 parts of rheology control agents, 3 parts of nonionic surfactants, 1.5 parts of organic polymer crosslinking agents, 1.5 parts of flexible fibers, and 0.3 parts of initiators; The nonionic monomer is N-vinyl pyrrolidone; The rheology control agent is obtained by mixing nano silicon dioxide and nano calcium carbonate in a mass ratio of 1:1; The initiator is sodium bisulfite; The rest is the same as in Example 3.

[0027] A method for preparing a high-strength shear-responsive gel for drilling plugging, comprising the following steps: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) Adding an organic polymer crosslinking agent to solution A to obtain solution B, stirring the mixture at room temperature and 500 rpm for 10 min, transferring the mixture to a 60°C water bath, deoxygenating the mixture with nitrogen at a flow rate of 2 L / min for 20 min, and then sequentially adding a nonionic surfactant, a flexible fiber, and a rheology control agent, stirring the mixture at room temperature and 200 rpm for 50 min to obtain a mixed solution; (3) Add the initiator to 5 parts of deionized water, and then slowly add it to the mixed solution obtained in step (2) at a dropping rate of 3 drops per second under stirring, continue stirring for 30 minutes, and let it stand at 30°C for 8 hours to obtain a high-strength shear-responsive gel for drilling plugging.

[0028] Example 6 A high-strength shear-responsive gel for plugging leaks in drilling, comprising the following raw materials in parts by weight: 100 parts of deionized water, 18 parts of nonionic monomers, 5 parts of rheology control agents, 2.5 parts of nonionic surfactants, 1 part of organic polymer crosslinking agents, 1 part of flexible fibers, and 0.2 parts of initiators; The nonionic monomer is a mixture of acrylamide and N-isopropylacrylamide in a mass ratio of 1.6:1; The flexible fiber is a mixture of polyester fiber and polypropylene fiber in a mass ratio of 1:2; The rest is the same as in Example 3.

[0029] A method for preparing a high-strength shear-responsive gel for drilling plugging, comprising the following steps: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) Adding an organic polymer crosslinking agent to solution A to obtain solution B, stirring the mixture at room temperature and 500 rpm for 8 min, transferring the mixture to a 60°C water bath, deoxygenating the mixture with nitrogen at a flow rate of 1 L / min for 20 min, and then sequentially adding a nonionic surfactant, a flexible fiber, and a rheology control agent, stirring the mixture at room temperature and 200 rpm for 30 min to obtain a mixed solution; (3) Add the initiator to 5 parts of deionized water, and then slowly add it to the mixed solution obtained in step (2) at a dropping rate of 3 drops per second under stirring, continue stirring for 30 minutes, and let it stand at 20°C for 7 hours to obtain a high-strength shear-responsive gel for drilling plugging.

[0030] Comparative Example 1 The gel plugging agent prepared in Example 1 of the CN 112480887B patent was used.

[0031] Performance Testing The gels provided in Examples 3 and 4 were tested for the relationship between viscosity and shear rate and the injection volume and water flooding breakthrough pressure to explore the gel shear thixotropy and plugging strength, and whether the retention capacity is good. The results are shown in Figure 1-Figure 4 .

[0032] Depend on Figure 1 and Figure 3 The test results show that when the shear rate is close to zero, the apparent viscosity of the plugging agent increases sharply, and the viscosity of the plugging agent can reach up to 106 mPa•s, when the shear rate gradually increases, the overall change of the apparent viscosity of the plugging agent slows down. In the range of 0-200 shear rates, the overall viscosity shows a downward trend, which is significantly slower than before. When the shear rate is above 200, the viscosity does not change significantly, but the overall viscosity trend shows a decreasing trend. The experimental results show that the high-strength shear-responsive gel prepared by the present invention has the shear thixotropic characteristics of "shear dilution and static thickening".

[0033] Depend on Figure 2 and Figure 4 The test results show that the breakthrough pressure gradient and water drive breakthrough pressure gradient increase with the increase of the injected water volume, but when the injection volume reaches 0.8pv, although the water drive breakthrough pressure and breakthrough pressure gradient also increase, the increase rate decreases. The preferred injection volume is 0.8pv. Under this injection volume, the shear response gel plugging strength can reach about 6.5MPa.

[0034] The gel plugging agents prepared in Example 3 and Comparative Example 1 were used, and a high-pressure resistant fracture plate model was used to inject different volumes of shear-responsive gel into the vertical fractures at a high injection rate of 5-10 mL / s. After the gel plugging agents were solidified, reverse water drive was performed to examine the degree of plugging of the fracture space by different injected volumes of plugging agents.

[0035] according to Figure 5 The injection volume and water drive breakthrough pressure test results show that the high-strength shear responsive gel prepared in the present invention can form a denser and firmer plugging structure when the injection volume is 0.8pv, improve the pressure-bearing plugging capacity, and effectively enhance the plugging effect under complex working conditions.

Claims

1. A high-strength shear-responsive gel for plugging leaks in drilling, characterized in that it is composed of the following raw materials in parts by weight: 100 parts of deionized water, 18-21 parts of non-ionic monomers, 5-6 parts of rheology control agents, 2-3 parts of non-ionic surfactants, 1-1.5 parts of organic polymer crosslinking agents, 1-1.5 parts of flexible fibers, and 0.2-0.3 parts of initiators; The nonionic surfactant is a synthetic nonionic surfactant PTB, which is prepared according to the following method, the specific steps are: (1) Mix 1,12-diaminododecane and cyclobutane-3-enedicarboxylic anhydride in a mass ratio of 1.05:1, placed in a container, passed nitrogen for 20 minutes to deoxygenate, reacted at 150-200°C for 3-4 hours to perform nucleophilic addition-elimination reaction to generate imide; (2) The imide obtained in step (1) is rapidly cooled to room temperature, and one-half of the cooled imide is taken, and the imide and the polyol are placed in a container and mixed at a mass ratio of 1:2.5, and anhydrous xylene is added. The oil bath is heated to 60-70° C. while stirring at a speed of 300-500 rpm, until the polyol is completely dissolved to form a uniform transparent solution; (3) Add the remaining half of the cooled imide of step (2) dropwise to the transparent solution obtained in step (2) while continuing to stir, control the reaction temperature to 70-80° C., and react for 2-3 h. After the reaction is complete, a mixture is obtained, and the mixture is cooled to room temperature in a nitrogen stream, purified, and vacuum dried to obtain a synthetic nonionic surfactant PTB.

2. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 1, characterized in that: The vacuum drying temperature in step (3) is 50°C and the time is 12 to 24 hours; the dripping speed is 1 to 2 drops per second.

3. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 1, characterized in that: The nonionic monomer is one or more of acrylamide, N-isopropylacrylamide and N-vinylpyrrolidone.

4. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 3, characterized in that: The rheology control agent is one or both of nano silicon dioxide and nano calcium carbonate.

5. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 4, characterized in that: The organic polymer cross-linking agent is an organic boron cross-linking agent.

6. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 5, characterized in that: The flexible fiber is one or both of polyester fiber and polypropylene fiber.

7. The high-strength shear-responsive gel for plugging leaks in drilling according to claim 6, characterized in that: The initiator is ammonium persulfate, potassium persulfate or sodium bisulfite.

8. A method for preparing the high-strength shear-responsive gel for plugging leaks in drilling according to claim 1, characterized in that: The following steps are involved: (1) dissolving a nonionic monomer in 95 parts of deionized water to obtain a solution A; (2) adding an organic polymer cross-linking agent to solution A to obtain solution B, stirring the solution at room temperature and 500 rpm for 8-10 min, transferring the solution to a 60°C water bath, deoxygenating the solution with nitrogen for 20 min, then sequentially adding a nonionic surfactant, a flexible fiber, and a rheology control agent, stirring the solution at room temperature and 200 rpm for 30-50 min to obtain a mixed solution; (3) The initiator is added to 5 parts of deionized water, and then added dropwise to the mixed solution obtained in step (2) under stirring, and the stirring is continued for 30 minutes. The mixture is allowed to react to obtain a high-strength shear-responsive gel for drilling plugging.

9. The method for preparing a high-strength shear-responsive gel for plugging leaks in drilling according to claim 8, characterized in that: The nitrogen flow rate of the nitrogen deoxygenation in step (2) is 1-2 L / min.

10. The method for preparing the high-strength shear-responsive gel for plugging leaks in drilling according to claim 8, characterized in that: The temperature of the static reaction in step (3) is 20-30°C and the time is 6-8 hours; the dripping speed in step (3) is 2-4 seconds / drop.

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