Preparation method of graphene oxide-based organic-inorganic plugging agent and drilling fluid

Abstract

The application discloses a preparation method of graphene oxide-based organic-inorganic plugging agent and a drilling fluid, and relates to the technical field of material chemistry. The graphene oxide is subjected to ultrasonic dispersion and activation to obtain activated graphene oxide; zirconium chloride and benzoic acid compounds are taken and dissolved by solvents to obtain a zirconium chloride solution and a benzoic acid compound solution; the benzoic acid compound solution is added dropwise into the zirconium chloride solution and uniformly mixed, and under the condition of continuous stirring, the activated graphene oxide is added into the mixed solution of the benzoic acid compound and the zirconium chloride, and reacts for 3h-5h; after the reaction is completed, solvent thermal reaction is continuously carried out, the temperature is lowered to room temperature after the solvent thermal reaction is completed, and the organic-inorganic plugging agent is obtained through separation and purification. The organic-inorganic plugging agent prepared by the preparation method of the application overcomes the problem that the particles lose the nanometer size, and can effectively plug the micro-nano cracks in the shale formation.

Description

Technical Field

[0001] This invention relates to the field of materials chemistry, particularly to the field of drilling fluid additives and drilling fluid technology, and more specifically to a method for preparing an organic-inorganic plugging agent based on graphene oxide and a drilling fluid. Background Technology

[0002] The increasingly complex geological conditions in the exploration and development of oil and gas have placed higher demands on the stability of the wellbore. During the drilling process, drilling fluid filtrate can easily enter the formation through tiny pores under pressure differential. The transmission of hydraulic pressure in the microfractures causes fracture induction and development, which leads to poor wellbore stability and, in severe cases, wellbore collapse and other drilling accidents.

[0003] Wellbore instability has been a major engineering problem that has plagued the drilling industry for many years, and remains largely unresolved. Wellbore instability can lead to a series of complex downhole conditions such as leakage, blowout, collapse, stuck pipe, and deviation. This, in turn, prolongs the drilling cycle, increases drilling costs, reduces drilling speed, and seriously affects the economic benefits of oil and gas exploration and development.

[0004] Statistics show that wellbore instability in deep formations accounts for approximately 35% of the time required to handle complex drilling situations, and over 90% of wellbore instability occurs in shale formations, with hard and brittle shale formations accounting for about two-thirds of these. Wellbore stability is crucial for ensuring the efficient development of oil and gas resources, and strengthening the sealing of nanopores is one of the key measures to address wellbore instability.

[0005] Because commonly used plugging agents in drilling fluids have large particle sizes, they are difficult to effectively seal nanopores in shale formations. Therefore, nanoscale plugging agents are needed to seal them.

[0006] Currently, commonly used drilling fluid nanoparticle plugging agents are mainly classified into organic nanoparticle plugging agents, inorganic nanoparticle plugging agents, and organic-inorganic nanoparticle plugging agents. Existing inorganic nanoparticle plugging agents are prone to agglomeration during use, leading to a sharp increase in particle size. Organic-inorganic nanoparticle plugging agents, due to hybridization processes during preparation, result in the loss of nanoscale particles. Therefore, synthesizing a plugging agent with nanoscale dimensions would be a good option for sealing nanofractures in shale.

[0007] Existing oil-based drilling fluids still have many shortcomings, especially in sealing nanoscale fractures, where their sealing effect urgently needs further improvement. Summary of the Invention

[0008] To overcome the defects and shortcomings of the existing technology, this invention provides a method for preparing an organic-inorganic plugging agent based on graphene oxide and a drilling fluid. The purpose of this invention is to solve the problem that the prepared organic-inorganic plugging agents lose their nanoscale size due to the hybridization process during preparation. The organic-inorganic plugging agent prepared by the method of this invention overcomes the problem of particle loss of nanoscale size and can effectively plug micro-nano fractures in shale formations.

[0009] To address the problems existing in the prior art, the present invention is achieved through the following technical solution.

[0010] The first aspect of this invention provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the method comprising the following steps: S1. Ultrasonic dispersion and activation of graphene oxide were performed to obtain activated graphene oxide. S2. Take zirconium chloride and benzoic acid compounds and dissolve them separately in solvents to obtain zirconium chloride solution and benzoic acid compound solution; S3. Add the benzoic acid compound solution dropwise to the zirconium chloride solution and mix evenly. Under continuous stirring, add the activated graphene oxide to the mixed solution of benzoic acid compound and zirconium chloride and react for 3-5 hours. After the reaction is completed, continue the solvothermal reaction. After the solvothermal reaction is completed, cool down to room temperature and separate and purify it to obtain the organic-inorganic blocking agent. In the above preparation method, the molar ratio of zirconium chloride and benzoic acid compounds is 1:(1-1.6); the amount of activated graphene oxide added is 5%-15% of the total mass of zirconium oxide and benzoic acid compounds.

[0011] In a further preferred embodiment, the specific steps for ultrasonic activation of graphene oxide in step S1 are as follows: placing graphene oxide in ultrapure water, ultrasonically dispersing it for 2-3 hours, and drying it at 60℃-70℃ for 12-16 hours to obtain activated graphene oxide.

[0012] More preferably, in the step of ultrasonic activation of graphite oxide, the mass ratio of graphite oxide to ultrapure water is 1:(1000-1125).

[0013] More preferably, the benzoic acid compound is p-aminomethylbenzoic acid, 2,4-dimethylbenzoic acid, or 3,5-dimethylbenzoic acid.

[0014] More preferably, the solvent used in steps S3 and S4 is N,N-dimethylformamide.

[0015] More preferably, in step S4, the reaction conditions for the solvothermal reaction are: a reaction temperature of 120℃-130℃ and a reaction time of 24h-30h.

[0016] More preferably, in step S4, the separation and purification steps are as follows: After the solvothermal reaction and cooling to room temperature, the product is subjected to solid-liquid separation. The solid phase is then washed multiple times with N,N-dimethylformamide and methanol. After washing, the solid phase is soaked in methanol for 24-30 hours. After soaking, it is dried at 60-70°C to obtain the organic-inorganic blocking agent.

[0017] A second aspect of the present invention provides a drilling fluid, which, based on 100 parts by weight of water, comprises the following components: 2-5 parts bentonite; 0.1-0.5 parts NaOH; 0.01-0.05 parts KPAM; 0.3-0.9 parts PAC-LV; 4-8 RSTFs; 5-8 copies of SMP-1; 3-6 parts FRH; 1-2 copies of PPL; 4-5 portions of FK-10; 0.3-0.6 parts SP-80; 1 to 5 parts of the organic-inorganic plugging agent described in the first aspect above; 1-1.6 parts desulfurizer; 0.3-0.6 parts CaO; 5-20 parts barite.

[0018] More preferably, in the drilling fluid, based on 100 parts by weight of water, the amount of organic-inorganic plugging agent added is 2 to 4 parts.

[0019] More preferably, in the drilling fluid, based on 100 parts by weight of water, the amount of organic-inorganic plugging agent added is 3 parts.

[0020] Compared with the prior art, the technical effects of this invention are manifested in the following aspects: 1. In this invention, zirconium chloride is selected as the metal ion source, and benzoic acid compounds are used as organic ligands to construct metal-organic frameworks (MOFs). Zirconium chloride provides stable metal nodes, and the specific structure of benzoic acid compounds makes them ideal organic ligands. This combination of raw materials allows for sufficient coordination between metal ions and organic ligands in subsequent reactions, forming a stable and ordered MOF framework. The high specific surface area and high porosity of MOFs provide a large number of adsorption sites and efficient pore structures for the plugging agent, which helps it play a key role in the plugging of micro- and nano-fractures in shale formations.

[0021] During the critical stage of MOF formation, activated graphene oxide dispersion was dropwise added to a mixed solution of benzoic acid compounds and zirconium chloride, and the reaction was continued for 3-5 hours followed by a solvothermal reaction. In this process, graphene oxide interacts with the forming MOFs. On one hand, oxygen-containing functional groups (such as carboxyl, hydroxyl, and epoxy groups) on graphene oxide chemically bond or physically adsorb onto the metal nodes or organic ligands of the MOFs, thus successfully introducing graphene oxide into the MOF structure. On the other hand, the large specific surface area, high chemical stability, and high adsorption capacity of graphene oxide itself synergize with the characteristics of MOFs, giving the plugging agent superior performance. The two-dimensional sheet-like structure of graphene oxide can further stack and cover the pores and fracture surfaces of MOFs, refining the plugging pores and enhancing the plugging effect; the chemical reactivity of its oxygen-containing functional groups with the minerals on the shale surface further enhances the adhesion between the plugging agent and the formation.

[0022] 2. In this invention, zirconium chloride and benzoic acid compounds are dissolved in N,N-dimethylformamide to obtain zirconium chloride solution and benzoic acid compound solution, respectively. N,N-dimethylformamide, as an excellent solvent, can not only uniformly disperse the raw materials, but also provide a suitable chemical environment for the coordination reaction between metal ions and organic ligands in subsequent reactions, promoting the smooth progress of the reaction and ensuring the orderly growth of MOF structures.

[0023] 3. In this invention, the benzoic acid compound solution is added dropwise to the zirconium chloride solution and mixed thoroughly. This process strictly controls the initial reaction conditions and the contact mode of the reactants. Under continuous stirring, the metal ions and organic ligands can fully contact and undergo coordination reactions, gradually constructing the framework structure of MOFs. This precisely controlled mixing reaction process helps to form structurally regular and stable MOFs, thereby improving the overall performance of the plugging agent.

[0024] 4. In the preparation method of the organic-inorganic blocking agent of this invention, graphene oxide is activated by ultrasonic dispersion. The graphene oxide is ultrasonically dispersed in ultrapure water for 2-3 hours and then dried at 60℃-70℃ for 12-16 hours to obtain activated graphene oxide. This process not only achieves the transformation from graphene oxide to graphene oxide but also enables it to function better in subsequent reactions. The activated graphene oxide is dispersed in a solvent to form a dispersion, providing a good dispersion state for its composite with MOFs.

[0025] 5. The solvothermal reaction of this invention is carried out at a temperature of 120℃-130℃ for 24-30 hours. This specific reaction condition helps to further improve and stabilize the MOF structure. Under the high temperature and high pressure solvothermal environment, the crystal structure of MOFs can become more regular and internal defects can be reduced, thereby improving their physical and chemical properties. At the same time, this process also promotes the interaction between graphene oxide and MOFs, enabling them to better fuse and form a higher-performance organic-inorganic blocking agent.

[0026] 6. The separation and purification steps of this invention can further improve the quality of the organic-inorganic plugging agent. The product after the solvothermal reaction and cooling to room temperature undergoes solid-liquid separation. The solid phase is then washed multiple times with N,N-dimethylformamide and methanol, and then soaked in methanol for 24-30 hours. Finally, it is dried at 60-70°C to obtain the organic-inorganic plugging agent. This series of separation and purification steps effectively removes residual impurities and unreacted raw materials from the reaction process, improving the purity and quality of the plugging agent. Washing and soaking remove surface-adsorbed impurities, optimizing the surface properties of the plugging agent; the drying process makes the structure of the plugging agent more stable, ensuring that it can fully exert its excellent plugging performance in practical applications.

[0027] 7. The organic-inorganic plugging agent prepared using the method of this invention exhibits excellent plugging ability against micro- and nano-fractures in shale formations. It can effectively prevent drilling fluid from invading the formation, reduce damage to the formation, ensure the smooth progress of drilling operations, and maintain formation stability.

[0028] 8. The organic-inorganic plugging agent of this invention exhibits good compatibility with other components of the drilling fluid, enabling it to better adapt to various conditions during the drilling process and ensuring smooth drilling operations. When the plugging agent is added at a dosage of 3 wt%, it can effectively plug micro- and nano-fractures in shale formations, with a plugging rate of up to 96% or more. Compared to conventional nano-plugging agents, this drilling fluid exhibits better rheological properties and stability under reservoir conditions, maintaining good performance in complex underground environments. This ensures the drilling fluid functions properly during circulation and cuttings carrying, improving drilling efficiency and quality, and reducing downhole accidents. Attached Figure Description

[0029] Figure 1 This is a particle size distribution diagram of the organic-inorganic plugging agent based on graphene oxide in Example 1; Figure 2 This is a particle size distribution diagram of the organic-inorganic plugging agent based on graphene oxide in Example 2; Figure 3 This is a particle size distribution diagram of the organic-inorganic plugging agent based on graphene oxide in Example 3. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] Example 1 As a preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the preparation method comprising the following steps: Weigh 15 mg of graphite oxide and measure 16 mL of ultrapure water. Mix the graphite oxide and ultrapure water, disperse ultrasonically for 2.2 h, and dry at 60 °C for 12 h to obtain activated graphene oxide. Weigh 0.8 g of zirconium chloride and dissolve it in 35 mL of N,N-dimethylformamide solution and stir for 30 min. Weigh 0.6 g of p-aminomethylbenzoic acid and dissolve it in 35 mL of N,N-dimethylformamide solution and stir for 30 min. Then, slowly add the p-aminomethylbenzoic acid solution dropwise to the zirconium chloride solution and mix thoroughly. After mixing the solutions, 0.08 g of ultrasonically dispersed graphene oxide was slowly added and stirred continuously for 3 h. Finally, the mixed suspension was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 122 °C for 26 h. After cooling to 25 °C, it was centrifuged at 8000 r / min for 6 min and washed three times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 26 h. Finally, the sample was vacuum dried at 62 °C for 26 h to obtain the first organic-inorganic plugging agent based on graphene oxide. The particle size distribution of the prepared organic-inorganic plugging agent is shown in the figure. Figure 1 As shown.

[0032] Example 2 In another preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the specific preparation process of which is as follows: 19 mg of graphite oxide was weighed and 20 mL of ultrapure water was measured. The graphite oxide and ultrapure water were mixed and ultrasonically dispersed for 2.8 h, and then dried at 68 °C for 15 h to obtain activated graphene oxide. 0.9 g of zirconium chloride was weighed and dissolved in 40 mL of N,N-dimethylformamide solution and stirred for 40 min. 0.85 g of 2,4-dimethylbenzoic acid was weighed and dissolved in 40 mL of N,N-dimethylformamide solution and stirred for 40 min. Then, the 2,4-dimethylbenzoic acid solution was slowly added dropwise to the zirconium chloride solution and mixed thoroughly. After mixing the two solutions, 0.16 g of ultrasonically dispersed graphene oxide was slowly added and stirred continuously for 5 h. Finally, the mixed suspension was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 130 °C for 30 h. After cooling to 25 °C, it was centrifuged at 10000 r / min for 8 min and washed five times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 30 h. Finally, the sample was vacuum dried at 68 °C for 30 h to obtain the No. 2 organic-inorganic plugging agent based on graphene oxide. The particle size distribution of the prepared organic-inorganic plugging agent is shown in the figure. Figure 2 As shown.

[0033] Example 3 In another preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the specific preparation process of which is as follows: Weigh 16 mg of graphite oxide and measure 18 mL of ultrapure water. Mix the graphite oxide and ultrapure water, then ultrasonically disperse for 2.5 h and dry at 66 °C for 13 h to obtain activated graphene oxide. Weigh 0.6 g of zirconium chloride and dissolve it in 36 mL of N,N-dimethylformamide solution and stir for 36 min. Weigh 0.45 g of 3,5-dimethylbenzoic acid and dissolve it in 36 mL of N,N-dimethylformamide solution and stir for 36 min. Then, slowly add the 3,5-dimethylbenzoic acid solution dropwise to the zirconium chloride solution and mix. After uniformly mixing the two solutions, 0.12 g of ultrasonically dispersed GO was slowly added and continuously stirred for 4 h. Finally, the mixed suspension was transferred to a PTFE-lined stainless steel autoclave and heated at 126 °C for 27 h. After cooling to 25 °C, it was centrifuged at 9000 r / min for 7 min and washed four times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 27 h. Finally, the sample was vacuum dried at 67 °C for 27 h to obtain the No. 3 organic-inorganic plugging agent based on graphene oxide. The particle size distribution of the prepared organic-inorganic plugging agent is as follows: Figure 3 As shown.

[0034] Example 4 In another preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the specific preparation process of which is as follows: Weigh 15 mg of graphene oxide and measure 15 mL of ultrapure water. Mix the graphene oxide and ultrapure water, disperse them by ultrasonication for 2 h, and dry them at 60 °C for 16 h to obtain activated graphene oxide.

[0035] 0.5 g of zirconium chloride was weighed and dissolved in 30 mL of N,N-dimethylformamide solution and stirred for 30 min. 0.32 g of p-aminomethylbenzoic acid was weighed and dissolved in 30 mL of N,N-dimethylformamide solution and stirred for 30 min. The p-aminomethylbenzoic acid solution was slowly added dropwise to the zirconium chloride solution and mixed thoroughly. After mixing the two solutions, 0.04 g of ultrasonically dispersed graphene oxide was slowly added and stirred continuously for 3 h. Finally, the mixed suspension was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 120 °C for 30 h. After cooling to 25 °C, it was centrifuged at 8000 r / min for 6 min and washed three times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 30 h. Finally, the sample was vacuum dried at 60 °C for 30 h to obtain No. 4 organic-inorganic blocking agent based on graphene oxide.

[0036] Example 5 In another preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the specific preparation process of which is as follows: Weigh 20 mg of graphene oxide and measure 20 mL of ultrapure water. Mix the graphene oxide and ultrapure water, sonicate for 3 h, and dry at 70 °C for 12 h to obtain activated graphene oxide. Weigh 0.4 g of zirconium chloride and dissolve it in 25 mL of N,N-dimethylformamide solution and stir for 30 min. Weigh 0.41 g of 2,4-dimethylbenzoic acid and dissolve it in 25 mL of N,N-dimethylformamide solution and stir for 30 min. Slowly add the 2,4-dimethylbenzoic acid solution to the zirconium chloride solution and mix thoroughly. After mixing the two solutions, slowly add 0.12 g of ultrasonically dispersed graphene oxide and stir continuously for 5 h. Finally, transfer the mixed suspension to a polytetrafluoroethylene-lined stainless steel autoclave and heat at 130 °C for 24 h. After cooling to 25 °C, centrifuge at 10000 r / min for 8 min and wash five times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 24 hours, and finally, the sample was vacuum dried at 70°C for 24 hours to obtain No. 5 organic-inorganic blocking agent based on graphene oxide.

[0037] Example 6 In another preferred embodiment of the present invention, this embodiment provides a method for preparing an organic-inorganic plugging agent based on graphene oxide, the specific preparation process of which is as follows: 17 mg of graphene oxide was weighed and 18.5 mL of ultrapure water was measured. The graphene oxide and ultrapure water were mixed and ultrasonically dispersed for 2.5 h, then dried at 65 °C for 14 h to obtain activated graphene oxide. 0.65 g of zirconium chloride was weighed and dissolved in 32 mL of N,N-dimethylformamide solution and stirred for 35 min. 0.48 g of 3,5-dimethylbenzoic acid was weighed and dissolved in 32 mL of N,N-dimethylformamide solution and stirred for 35 min. The 3,5-dimethylbenzoic acid solution was slowly added dropwise to the zirconium chloride solution and mixed thoroughly. After mixing the two solutions, 0.11 g of ultrasonically dispersed graphene oxide was slowly added and stirred continuously for 4 h. Finally, the mixed suspension was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 125 °C for 27 h. After cooling to 25°C, the sample was centrifuged at 9000 r / min for 7 min and washed four times each with N,N-dimethylformamide and methanol. The centrifuged sample was then soaked in methanol for 27 h, and finally vacuum dried at 65°C for 27 h to obtain No. 6, an organic-inorganic blocking agent based on graphene oxide.

[0038] Example 7 As another preferred embodiment of the present invention, this embodiment provides a drilling fluid with the following formulation: based on 100 parts by weight of water, 100 parts by weight of water + 2 parts by weight of bentonite + 0.1 parts by weight of NaOH + 0.01 parts by weight of KPAM + 0.3 parts by weight of PAC-LV + 4 parts by weight of RSTF + 5 parts by weight of SMP-1 + 3 parts by weight of FRH + 1 part by weight of PPL + 4 parts by weight of FK-10 + 0.3 parts by weight of SP-80 + 1 part by weight of the organic-inorganic plugging agent described in any one of the embodiments 1-6 above + 1 part by weight of desulfurizer + 0.3 parts by weight of CaO + 5 parts by weight of barite.

[0039] The preparation steps are as follows: Prehydration of bentonite slurry: At room temperature, add 2 parts by weight of bentonite evenly to 100 parts by weight of tap water while stirring, then add an appropriate amount of soda ash (adjust according to actual needs), stir for 30 minutes at a speed of 2000 r / min, seal and let stand for 24 hours to obtain prehydrated bentonite slurry. Preparation of the base slurry: In the prehydrated bentonite slurry prepared above, stir for 5 minutes at 2500 rpm. Then, add sequentially the following substances: 0.01 parts by weight of KPAM, 0.3 parts by weight of PAC-LV, 4 parts by weight of RSTF, 5 parts by weight of SMP-1, 3 parts by weight of FRH, 1 part by weight of PPL, 4 parts by weight of FK-10, 0.3 parts by weight of SP-80, 1 part by weight of organic-inorganic sealing agent, 1 part by weight of desulfurizing agent, 0.3 parts by weight of CaO, and 5 parts by weight of barite. After each substance is added, stir for 10–15 minutes before adding the next substance.

[0040] Example 8 As another preferred embodiment of the present invention, this embodiment provides a drilling fluid with the following formulation: based on 100 parts by weight of water, 100 parts by weight of water + 3.5 parts by weight of bentonite + 0.3 parts by weight of NaOH + 0.03 parts by weight of KPAM + 0.6 parts by weight of PAC-LV + 6 parts by weight of RSTF + 6.5 parts by weight of SMP-1 + 4.5 parts by weight of FRH + 1.5 parts by weight of PPL + 4.5 parts by weight of FK-10 + 0.45 parts by weight of SP-80 + 3 parts by weight of the organic-inorganic plugging agent described in any one of the embodiments 1-6 above + 1.3 parts by weight of desulfurizer + 0.45 parts by weight of CaO + 12.5 parts by weight of barite.

[0041] The preparation steps are as follows: At room temperature, 3.5 parts by weight of bentonite are evenly added to 100 parts by weight of tap water while stirring, followed by an appropriate amount of soda ash (adjusted proportionally according to actual needs). The mixture is stirred at 2000 r / min for 30 minutes, then sealed and allowed to stand for 24 hours to obtain a pre-hydrated bentonite slurry. In the pre-hydrated bentonite slurry prepared above, after stirring for 5 minutes at 2500 r / min, the following substances are added sequentially: 0.03 parts by weight of KPAM, 0.6 parts by weight of PAC-LV, 6 parts by weight of RSTF, 6.5 parts by weight of SMP-1, 4.5 parts by weight of FRH, 1.5 parts by weight of PPL, 4.5 parts by weight of FK-10, 0.45 parts by weight of SP-80, 3 parts by weight of organic-inorganic sealing agent, 1.3 parts by weight of desulfurizing agent, 0.45 parts by weight of CaO, and 12.5 parts by weight of barite. Each time a substance is added, it needs to be stirred for 10-15 minutes before adding the next substance.

[0042] Example 9 As another preferred embodiment of the present invention, this embodiment provides a drilling fluid with the following formulation: based on 100 parts by weight of water, 100 parts by weight of water + 5 parts by weight of bentonite + 0.5 parts by weight of NaOH + 0.05 parts by weight of KPAM + 0.9 parts by weight of PAC-LV + 8 parts by weight of RSTF + 8 parts by weight of SMP-1 + 6 parts by weight of FRH + 2 parts by weight of PPL + 5 parts by weight of FK-10 + 0.6 parts by weight of SP-80 + 5 parts by weight of the organic-inorganic plugging agent described in any one of the embodiments 1-6 above + 1.6 parts by weight of desulfurizer + 0.6 parts by weight of CaO + 20 parts by weight of barite.

[0043] The preparation steps are as follows: Pre-hydration of bentonite slurry: At room temperature, add 5 parts by weight of bentonite evenly to 100 parts by weight of tap water while stirring, then add an appropriate amount of soda ash (adjust according to actual needs). Stir at 2000 r / min for 30 min, then seal and let stand for 24 h to obtain pre-hydrated bentonite slurry; Preparation of base slurry: In the pre-hydrated bentonite slurry prepared above, stir at 2500 r / min for 5 min, then add 0.05 parts by weight of KPAM, 0.9 parts by weight of PAC-LV, 8 parts by weight of RSTF, 8 parts by weight of SMP-1, 6 parts by weight of FRH, 2 parts by weight of PPL, 5 parts by weight of FK-10, 0.6 parts by weight of SP-80, 5 parts by weight of organic-inorganic sealing agent, 1.6 parts by weight of desulfurizer, 0.6 parts by weight of CaO, and 20 parts by weight of barite. After each substance is added, stir for 10-15 min before adding the next substance.

[0044] To further illustrate the performance of the organic-inorganic plugging agent of this application, the following examples are provided.

[0045] Example 10 As another preferred embodiment of the present invention, this embodiment provides a drilling fluid with the following formulation: based on 100 parts by weight of water, 100 parts by weight of water + 3 parts by weight of bentonite + 0.3 parts by weight of NaOH + 0.03 parts by weight of KPAM + 0.6 parts by weight of PAC-LV + 6 parts by weight of RSTF + 6 parts by weight of SMP-1 + 4 parts by weight of FRH + 1.5 parts by weight of PPL + 4.5 parts by weight of FK-10 + 0.5 parts by weight of SP-80 + 1.5 parts by weight of desulfurizer + 0.5 parts by weight of CaO + 12 parts by weight of barite.

[0046] 1) Prehydration of bentonite slurry At room temperature, 3 parts by weight of bentonite are evenly added to 100 parts by weight of tap water while stirring, and then 0.3 parts by weight of soda ash is added. After stirring at 2000 r / min for 30 min, the mixture is sealed and allowed to stand for 24 h to obtain prehydrated bentonite slurry.

[0047] 2) To the prehydrated bentonite slurry prepared in step 1), stir at 2500 r / min for 5 min, then sequentially add 0.03 parts by weight of KPAM, 0.6 parts by weight of PAC-LV, 6 parts by weight of RSTF, 6 parts by weight of SMP-1, 4 parts by weight of FRH, 1.5 parts by weight of PPL, 4.5 parts by weight of FK-10, 0.5 parts by weight of SP-80, 1.5 parts by weight of desulfurizing agent, 0.5 parts by weight of CaO, and 12 parts by weight of barite. After each addition of a substance, stir for 10-15 min before adding the next substance to obtain the base slurry.

[0048] 3) Take 4 equal amounts of the base slurry prepared in step 2) into 4 enamel measuring cups, and add 1, 2, 3 and 4 parts by weight of the No. 1 organic-inorganic plugging agent based on graphene oxide synthesized in Example 1 at a speed of 2500 r / min. Stir for 30 min to obtain drilling fluids 1-4 with different amounts of plugging agent.

[0049] 4) Using the same method, add the graphene oxide-based organic-inorganic plugging agent synthesized in Example 2 to obtain drilling fluids 5-8 with different plugging agent dosages. Using the same method, add the graphene oxide-based organic-inorganic plugging agent synthesized in Example 3 to obtain drilling fluids 9-12 with different plugging agent dosages.

[0050] 3. Performance Testing: To further illustrate the effects of the graphene oxide-based organic-inorganic plugging agent and drilling fluid of the present invention, performance tests were conducted on the graphene oxide-based organic-inorganic plugging agent and drilling fluid prepared in Examples 1, 2 and 3.

[0051] (1) Particle size testing of organic-inorganic plugging agents based on graphene oxide The particle size of the graphene oxide-based organic-inorganic plugging agents was measured using a BI-200SM laser scattering instrument manufactured by Brookhaven Instruments, Inc., USA. The particle size test results of the graphene oxide-based organic-inorganic plugging agents prepared in the three examples are as follows: Figure 1 , Figure 2 , Figure 3 As shown. The organic-inorganic plugging agents based on graphene oxide of this invention have particle sizes of nano-micron, and are roughly distributed between 45-1350 nm, which have a high degree of matching with the nano-micron level crack size in shale, and can effectively plug them.

[0052] (2) Testing of the plugging performance of organic-inorganic plugging agents based on graphene oxide Measure 1000g of the aforementioned prehydrated bentonite slurry and stir it electrically at 8000r / min for 30 minutes. Then, add 50g of SMP-1, 50g of SMC, 1.5g of HF-1, and 100g of 6000-mesh barite in sequence. After adding each substance, stir for 15 minutes before adding the next substance. Then, heat the slurry at 150℃ for 16 hours.

[0053] After stirring the above mixture evenly for 10 minutes, take 100 mL and transfer it to a high temperature and high pressure water loss tester. Set the temperature to 150℃ and the pressure to 3.5MPa. Under these conditions, lose water for 30 minutes to obtain a mud cake. Then calculate the permeability of the mud cake according to formula (1-1).

[0054] (1-1); where K represents the permeability, 10 -1 μm 2 Q represents the filtration loss of distilled water through the filter cake per unit time under a pressure difference of 3.5 MPa, in cm. 3 / s; A represents the cross-sectional area of ​​the mud cake, in cm² 2 ; Indicates the thickness of the mud cake, in cm; ΔP represents the fluid viscosity passing through the mud cake, in mPa•s; ΔP represents the pressure difference of the fluid before and after passing through the mud cake, in MPa.

[0055] The area of ​​the filter cake is A = 23.8 cm². 2 The pressure difference due to filtration loss is ∆P = 3.5 MPa; then, according to formula (1-2), the plugging rate of the organic-inorganic plugging agent based on graphene oxide is calculated for different dosages; In the formula, K w K represents the plugging efficiency after plugging with the graphene oxide-based organic-inorganic plugging agent, in percentages (%). K0 represents the cake permeability before plugging with the graphene oxide-based organic-inorganic plugging agent, in ten percent. -1 μm 2 K1 represents the permeability of the sludge cake after plugging with an organic-inorganic plugging agent based on graphene oxide, 10 -1 μm 2 .

[0056] Filter cakes were prepared according to the method described above. Filter cakes with similar permeability were selected. 100 mL of different amounts of graphene oxide-based organic-inorganic plugging agent were prepared and ultrasonically dispersed for 10 min. The mixture was then transferred to a high-temperature and high-pressure water loss analyzer containing the filter cakes. The test was conducted sequentially under the same conditions of 150℃ and 3.5 MPa. The readings were recorded every 5 min and the test was conducted for 30 min. The filter cakes were then removed, dried with a blower, and the permeability of the different amounts of graphene oxide-based organic-inorganic plugging agent was calculated using the formula. The results are shown in Table 1.

[0057] Table 1. Test data on the sealing performance of mud cake. As shown in the table above, the graphene oxide-based organic-inorganic plugging agent can effectively reduce cake permeability. When the dosage of the graphene oxide-based organic-inorganic plugging agent is 1 wt%, the permeability of the cake in Examples 1-3 decreased by 80.15%, 80.67%, and 79.64%, respectively. The plugging effect is better with increasing dosage of the graphene oxide-based organic-inorganic plugging agent. However, when the dosage exceeds 3 wt%, the cake permeability continues to decrease, but the decrease is almost negligible. This indicates that the graphene oxide-based organic-inorganic plugging agent of the present invention has a good effect on low permeability cakes, and the optimal dosage of the graphene oxide-based organic-inorganic plugging agent of the present invention is 3 wt%.

[0058] (3) Drilling fluid performance testing Based on the drilling fluid preparation described above, the graphene oxide-based organic-inorganic plugging agent prepared in Examples 1-3 was replaced with the commonly used plugging material MB-1 (a rigid plugging material mainly composed of barium sulfate) to prepare three drilling fluids for comparison. Then, the three comparative examples were placed under the same conditions for drilling fluid performance testing.

[0059] Table 2 Drilling Fluid Performance Parameters Note: HTHP has a temperature of 150℃ and a pressure of 3.5MPa.

[0060] As shown in the table above, the drilling fluids formulated with the graphene oxide-based organic-inorganic plugging agents prepared in Examples 1, 2, and 3 have YP / PV values ​​of 0.42, 0.45, and 0.42, respectively. In these cases, the flow type of the drilling fluid in the annulus is a flat-plate laminar flow, characterized by high rock-carrying capacity at low viscosity and minimal scouring effect on the wellbore. Therefore, this drilling fluid exhibits good rheological properties. Furthermore, compared with the drilling fluid using rigid plugging material MB-1 as the plugging agent, the drilling fluids from all examples show lower API high-temperature and high-pressure filtration loss. Therefore, the drilling fluid formulated with the graphene oxide-based organic-inorganic plugging agent synthesized in this invention has better performance.

Claims

1. A method for preparing an organic-inorganic plugging agent based on graphene oxide, characterized in that: The preparation method includes the following steps: S1. Ultrasonic dispersion and activation of graphene oxide were performed to obtain activated graphene oxide. S2. Take zirconium chloride and benzoic acid compounds and dissolve them separately in solvents to obtain zirconium chloride solution and benzoic acid compound solution; S3. Add the benzoic acid compound solution dropwise to the zirconium chloride solution and mix evenly. Under continuous stirring, add the activated graphene oxide to the mixed solution of benzoic acid compound and zirconium chloride and react for 3-5 hours. After the reaction is completed, continue the solvothermal reaction. After the solvothermal reaction is completed, cool down to room temperature and separate and purify it to obtain the organic-inorganic blocking agent. In the above preparation method, the molar ratio of zirconium chloride and benzoic acid compounds is 1:(1-1.6); the amount of activated graphene oxide added is 5%-15% of the total mass of zirconium oxide and benzoic acid compounds.

2. The preparation method of the organic-inorganic plugging agent based on graphene oxide as described in claim 1, characterized in that: In step S1, the specific steps for ultrasonic activation of graphene oxide are as follows: graphene oxide is placed in ultrapure water, ultrasonically dispersed for 2-3 hours, and dried at 60℃-70℃ for 12-16 hours to obtain activated graphene oxide.

3. The preparation method of the organic-inorganic plugging agent based on graphene oxide as described in claim 2, characterized in that: In the step of ultrasonic activation of graphite oxide, the mass ratio of graphite oxide to ultrapure water is 1:(1000-1125).

4. The method for preparing the organic-inorganic plugging agent based on graphene oxide as described in any one of claims 1-3, characterized in that: The benzoic acid compounds are p-aminomethylbenzoic acid, 2,4-dimethylbenzoic acid, or 3,5-dimethylbenzoic acid.

5. The method for preparing the organic-inorganic plugging agent based on graphene oxide as described in any one of claims 1-3, characterized in that: The solvent used in steps S3 and S4 is N,N-dimethylformamide.

6. The method for preparing the organic-inorganic plugging agent based on graphene oxide as described in claim 5, characterized in that: In step S4, the reaction conditions for the solvothermal reaction are: a reaction temperature of 120℃-130℃ and a reaction time of 24h-30h.

7. The method for preparing the organic-inorganic plugging agent based on graphene oxide as described in any one of claims 1-3, characterized in that: In step S4, the separation and purification steps are as follows: After the solvothermal reaction and cooling to room temperature, the product is subjected to solid-liquid separation. The solid phase is then washed multiple times with N,N-dimethylformamide and methanol. After washing, the solid phase is soaked in methanol for 24-30 hours. After soaking, it is dried at 60-70°C to obtain the organic-inorganic blocking agent.

8. Drilling fluid, characterized in that: This drilling fluid, based on 100 parts by weight of water, includes the following components: 2-5 parts bentonite; 0.1-0.5 parts NaOH; 0.01-0.05 parts KPAM; 0.3-0.9 parts PAC-LV; 4-8 RSTFs; 5-8 copies of SMP-1; 3-6 parts FRH; 1-2 copies of PPL; 4-5 portions of FK-10; 0.3-0.6 parts SP-80; The organic-inorganic plugging agent is prepared by the method of any one of claims 1-7 using 1-5 parts of the organic-inorganic plugging agent based on graphene oxide. 1-1.6 parts desulfurizer; 0.3-0.6 parts CaO; 5-20 parts barite.

9. The drilling fluid as described in claim 8, characterized in that: In the drilling fluid, based on 100 parts by weight of water, the amount of organic-inorganic plugging agent added is 2 to 4 parts.

10. The drilling fluid as described in claim 8 or 9, characterized in that: In the drilling fluid, based on 100 parts by weight of water, the amount of organic-inorganic plugging agent added is 3 parts.

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