Supramolecular material diverting agent for hydraulic fracturing and preparation method and application thereof

Abstract

The application discloses a supramolecular material diverting agent for hydraulic fracturing and a preparation method and application thereof. By adding an initiator, raw polymer is changed from an oligomer into a novel copolymer, the surface chemical properties of the intrinsic material are changed, the supramolecular material has better temperature resistance, the oil reservoir temperature is 30-150 DEG C, and the supramolecular material has a wide use temperature range. The supramolecular material has a self-crosslinking characteristic activated by environmental heat, compared with a physically stacked temporary plugging agent material, the chemical crosslinking characteristic of the supramolecular material makes the supramolecular material have better plugging performance. In addition, the supramolecular material also has a self-degradation characteristic, the degradation process can be accelerated by adjusting the pH of a fracturing fluid, and on-demand deblocking can be realized. By controlling the polymerization degree to adjust the thermal stability of the supramolecular material, the supramolecular material diverting agent has the performance of temporary plugging and long-acting plugging, and has a wide use range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield chemistry, in particular to a supramolecular material diverting agent for hydraulic fracturing, and a preparation method and application thereof. BACKGROUND

[0002] China has a large amount of unconventional oil and gas resources, and unconventional resources such as tight gas, shale oil and shale gas play an increasingly important role in oil and gas production. However, unconventional oil and gas reservoirs often have the characteristics of low porosity, low permeability and strong heterogeneity, which increases the difficulty of exploitation. Hydraulic fracturing is an important technology to improve the efficiency of unconventional oil and gas resource exploitation. By injecting fracturing fluid through a high-pressure pump on the ground, the rock layer is broken to produce cracks and expand to the oil and gas reservoir, thereby being exploited. Affected by the heterogeneity of the reservoir and the closure stress of the formation, the hydraulic fracture often expands unevenly, not only causing resource waste, but also seriously affecting oil and gas production. Therefore, during the implementation of hydraulic fracturing, how to achieve uniform expansion of the reservoir fracture is crucial for the increase of oil and gas production.

[0003] By injecting fracturing fluid containing diverting agent through a surface pump, the diverting agent "effectively" blocks the initial fracture or perforation in the formation, forming an out-of-joint blockage, causing the wellbore pressure or net pressure in the fracture to continue to rise, and causing the subsequent fracturing fluid to be diverted to a location other than the initial fracture. In addition, the diverting agent also has the effect of in-joint blockage of the main fracture, opening new branch fractures or activating natural fractures, and even multiple diversion, greatly improving the uniform expansion of the fracture. In order to improve the flowability of oil and gas to achieve the effect of increasing production, the diverting agent must complete deblocking within a specified time and efficiently flow back. This time-dependent diverting agent is also called temporary plugging agent. In addition, as oil and gas exploitation construction continues to advance, the heterogeneity of the reservoir causes the oil and gas production in some fracturing areas to decrease, and in order to improve the oil and gas recovery, secondary or multiple fracturing is needed. Therefore, it is necessary to implement long-term plugging in fracturing areas with low oil and gas production. With the implementation of the policy of green development of oilfields, it is urgent to develop a diverting agent with low toxicity, low cost and both temporary plugging and long-term plugging performance.

[0004] Supermolecular materials are considered to be good temporary plugging agents, which not only have low toxicity, but also have the characteristics of thermal activation self-crosslinking, injection into the formation, without adding other materials (crosslinking agent, breaker, etc.), with the increase of temperature, the material will gradually form a gel, these gels have the characteristics of high viscosity and high compressive strength, which can easily plug the cracks. If the temperature is further increased, the gel will break and restore to a liquid state, which is easy to flow back and restore the production capacity of the cracks, and theoretically can achieve 100% removal. However, the supermolecular materials currently used for diverting agents, such as polylactic acid and butylene glycol vinyl alcohol copolymer, have a strong temperature dependence on plugging performance. Studies have shown that polylactic acid needs 10 days to achieve 74% degradation at 80℃, while at 120℃, it only takes 10 hours to complete 100% degradation. In addition, in the low temperature zone, the applicable temperature of butylene glycol vinyl alcohol copolymer can be as low as 26℃, but in the medium and high temperature zone, the temporary plugging performance is greatly discounted. These temporary plugging agents not only have different applicable temperature ranges, but also cannot be deblocked on demand, increasing their use cost and limiting their development.

[0005] Chinese patent (CN118496837A) grafts carboxymethyl chitosan onto allyl glycidyl ether, and then obtains a network structure polymer through copolymerization and crosslinking. Then, the modified polymer microspheres are prepared by blending polylactic acid. Although this modified polymer microspheres can achieve deblocking on demand, the process is relatively complex, and the applicable temperature range is relatively narrow (80-100℃), which is not conducive to popularization and use. Chinese patent (CN118146775A) discloses a double-crosslinked thermal phase change gel temporary plugging agent, which is applied to oil and gas reservoirs with a temperature of 100-150℃, can automatically gel and degrade, and has a low filtration loss before gelling. However, this temporary plugging agent has complex components and high cost, and cannot be applied to medium and low temperature oil and gas reservoirs. US patent (US11053427B2) provides a low-density, high-strength, degradable temporary plugging agent, which is applicable at a temperature of 30-90℃, but cannot deblock on demand. Therefore, developing a supermolecular material diverting agent with a wide temperature range, controllable plugging time and deblocking time is helpful to promote the green development of oilfields, and has a broad market prospect. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide a supermolecular material diverting agent for hydraulic fracturing and a preparation method and application thereof. The prepared supermolecular material diverting agent has the characteristics of thermal activation self-crosslinking and self-degradation, controllable plugging time, wide applicable temperature range, and long-term plugging capacity.

[0007] The present application is realized by the following technical solutions:

[0008] A preparation method of a supermolecular material diverting agent for hydraulic fracturing, comprising the following steps:

[0009] Step one, disperse the polymer powder into the solvent, stir evenly to get reaction liquid A;

[0010] Step two, add initiator to reaction liquid A according to initiator and polymer powder mass ratio 1:(10-500), ultrasonic treatment to get reaction liquid B; the polymer powder is one or more of polyester polymer, polyether polymer and natural polymer; the initiator is one or more of peroxide, azo compound, hydroxide, silane coupling agent, sulfate, sulfite and surfactant;

[0011] Step three, first centrifugal treatment is carried out to reaction liquid B to remove the upper solution, then washing is carried out, after multiple centrifugal treatment, product C is obtained;

[0012] Step four, drying and grinding are carried out to product C, sieving is carried out, finally, the supermolecular material diverting agent with different particle sizes is obtained.

[0013] Preferably, the solvent is one or more of water, methanol, ethanol, acetone, toluene, chloroform; the stirring temperature is room temperature-100 DEG C; the stirring time is 30 min-48 h.

[0014] Preferably, the polyester polymer is polyvinyl acetate, polyethylene terephthalate or polybutylene terephthalate etc.; the polyether polymer is polyethylene glycol, polypropylene glycol or poly-p-phenylene ether; the natural polymer is cellulose, polysaccharide or starch.

[0015] Preferably, the peroxide is hydrogen peroxide, benzoic acid peroxide, diphenyl peroxide or tert-butyl peroxide; the azo compound is azobisisobutyronitrile, azodicarbonamide or azodicarboxylic ester; the hydroxide is sodium hydroxide or potassium hydroxide; the silane coupling agent is vinyl silane, amino silane or methacryloyloxy silane; the sulfate and sulfite are ammonium sulfate, sodium thiosulfate or sodium bisulfite; the surfactant is sodium dodecylbenzenesulfonate, lecithin, sodium dodecyl sulfate or sodium cetyl sulfate.

[0016] Preferably, the ultrasonic treatment frequency of step two is 20-40 kHz; the ultrasonic time is 2-8 h; the centrifugal speed of step three is 2000-6000 rpm / min; the drying temperature of step four is 60-100 DEG C.

[0017] Preferably, the reagent used for washing of step three is one or more of water, methanol, ethanol, propanol, dimethyl sulfoxide, N,N-dimethylformamide and N-methyl pyrrolidone.

[0018] The application also provides a supermolecular material diverting agent for hydraulic fracturing, the particle size range is 200 nm-2 cm.

[0019] The application also provides application of the supramolecular material diverting agent for hydraulic fracturing in the hydraulic fracturing technology of oil and gas fields.

[0020] Preferably, the degradation time of the diverting agent is accelerated by adjusting the pH value of the fracturing fluid to 3-6.

[0021] Preferably, the pH value of the fracturing fluid is adjusted by adding one or more of boric acid, phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid.

[0022] Compared with the prior art, the application has the beneficial effects that:

[0023] (1) The supramolecular material diverting agent prepared by the application changes the intrinsic material surface chemical properties by adding an initiator to change the raw material from an oligomer to a new copolymer, has better temperature resistance, and the thermal stability thereof can be further adjusted by adjusting the polymerization degree of the product. It is found through tests that the supramolecular material prepared by the application is suitable for a reservoir temperature of 30-150℃, and has a wide use temperature range; and has the characteristics of self-crosslinking and self-degradation through environmental thermal activation.

[0024] (2) The plugging time of the supramolecular material diverting agent prepared by the application is controllable, and the degradation process can be accelerated by adjusting the pH value of the fracturing fluid. Under acidic conditions, the surface hydroxyl groups of the diverting agent are passivated to easily form a crosslinked structure to form a plug. As the service time is prolonged, the molecular chain is broken, the degree of hydrolysis is deepened, and the mechanical properties are decreased, so the plugging ability is lost and the liquid state is gradually restored. Therefore, the degradation speed can be accelerated to achieve the purpose of controllable plugging time.

[0025] (3) The supramolecular material diverting agent prepared by the application has the performance of temporary plugging and long-term plugging. In addition to on-demand deblocking, as the fracturing operation is continuously carried out, many low-yield “waste” fractures are generated due to the heterogeneity of the reservoir after multiple fracturing. In order to not affect the oil and gas field recovery rate, long-term or even permanent plugging is required. The diverting agent has good temperature resistance, so it has the ability of long-term plugging and has a wide range of applications.

[0026] (4) The particle size of the supramolecular material diverting agent prepared by the application is controllable, and can be customized and used in combination according to the size of the microfracture, so as to realize the effect of external and external double plugging. Large particle materials are used to plug the main fracture to form external plugging; small particle materials are used for internal plugging of the main fracture of the branch fracture, multiple diversion plugging is carried out, and the uniform expansion of the fracture is improved.

[0027] (5) The chemical reagents used in the application have the characteristics of low toxicity and green environmental protection; and the method has low requirements for equipment, high yield and simple process flow. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1Static swelling test result graph of the diverting agent prepared for Example 1 of the present invention at 30°C;

[0029] Figure 2 Static swelling test result graph of the diverting agent prepared for Example 1 of the present invention at 50°C;

[0030] Figure 3 Static swelling test result graph of the diverting agent prepared for Example 1 of the present invention at 55°C;

[0031] Figure 4 Static swelling test result graph of the diverting agent prepared for Example 1 of the present invention at 50°C with addition of boric acid;

[0032] Figure 5 Dynamic filtration rate graph of the diverting agent prepared for Example 1 of the present invention at 30°C and 50°C;

[0033] Figure 6 Dynamic filtration rate graph of the diverting agent prepared for Example 1 of the present invention at 55°C;

[0034] Figure 7 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 70°C;

[0035] Figure 8 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 75°C;

[0036] Figure 9 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 80°C;

[0037] Figure 10 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 85°C;

[0038] Figure 11 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 90°C;

[0039] Figure 12 Static swelling test result graph of the diverting agent prepared for Example 2 of the present invention at 70°C with addition of boric acid;

[0040] Figure 13 Dynamic filtration rate graph of the diverting agent prepared for Example 2 of the present invention at 70°C;

[0041] Figure 14 Dynamic filtration rate graph of the diverting agent prepared for Example 2 of the present invention at 70°C, 75°C, 80°C and 85°C;

[0042] Figure 15Dynamic fluid loss plot of the diverting agent prepared for Example 2 of the present invention at 90°C;

[0043] Figure 16 Static swelling test result plot of the diverting agent prepared for Example 3 of the present invention at 30°C;

[0044] Figure 17 Static swelling test result plot of the diverting agent prepared for Example 3 of the present invention at 70°C;

[0045] Figure 18 Front view of the diverting agent prepared for Example 3 of the present invention at 30°C;

[0046] wherein (a) is the dynamic fluid loss plot of the diverting agent prepared for Example 3 of the present invention at 30°C;

[0047] (b) is the front view of the diverting agent prepared for Example 3 of the present invention after dynamic fluid loss test at 30°C;

[0048] (c) is the top view of the diverting agent prepared for Example 3 of the present invention after dynamic fluid loss test at 30°C;

[0049] Figure 19 Dynamic view of the diverting agent prepared for Example 3 of the present invention at 70°C

[0050] wherein (a) is the dynamic fluid loss plot of the diverting agent prepared for Example 3 of the present invention at 70°C;

[0051] (b) is the front view of the diverting agent prepared for Example 3 of the present invention after dynamic fluid loss test at 70°C;

[0052] (c) is the top view of the diverting agent prepared for Example 3 of the present invention after dynamic fluid loss test at 70°C;

[0053] Figure 20 Schematic diagram of the tight stacking of the diverting agent particles to the self-crosslinking. DETAILED DESCRIPTION

[0054] The present invention will be further described in conjunction with specific examples, which are intended to explain but not to limit the present invention.

[0055] Example 1: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, which comprises the following steps:

[0056] Step one, 10 g of starch and polyvinyl acetate powder were put into 100 g of distilled water, and continuous stirring was carried out at 60°C for 30 min to obtain reaction liquid A;

[0057] Step two, 0.1 g of hydrogen peroxide, vinyl silane and sodium dodecyl benzene sulfonate were added to the reaction liquid A, and ultrasonic treatment was carried out at room temperature for 2 h to obtain reaction liquid B;

[0058] Step three, the reaction liquid B was first centrifuged at 2000 rpm / min to remove the upper solution, then ethanol was added for washing, and the product C was obtained after multiple centrifugations;

[0059] Step four, the product C was dried at 60°C for 12 h and ground, and finally the average particle size of the supramolecular material diverting agent was 0.5 cm.

[0060] Example 2: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, which comprises the following steps:

[0061] Step one, 10 g of cellulose powder and polyethylene terephthalate were put into 100 g of distilled water and ethanol, and stirring was carried out at room temperature for 2 h to obtain reaction liquid A;

[0062] Step two, 0.1 g of methacryloyloxy silane, sodium thiosulfate and lecithin were added to the reaction liquid A, and ultrasonic treatment was carried out at room temperature for 2 h to obtain reaction liquid B;

[0063] Step three, the reaction liquid B was first centrifuged at 6000 rpm / min to remove the upper solution, then methanol was added for washing, and the product C was obtained after multiple centrifugations;

[0064] Step four, the product C was dried at 80°C for 12 h and ground, and finally the average particle size of the supramolecular material diverting agent was 0.1 cm.

[0065] Example 3: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, which comprises the following steps:

[0066] Step one, 10 g of starch powder was put into 200 g of distilled water and methanol mixed solution, and stirring was carried out at room temperature for 30 min to obtain reaction liquid A;

[0067] Step two, 0.1 g of vinyl silane, sodium dodecyl benzene sulfonate and sodium sulfite were added to the reaction liquid A, and ultrasonic treatment was carried out at room temperature for 2 h to obtain reaction liquid B;

[0068] Step three, the reaction liquid B was first centrifuged at 4000 rpm / min to remove the upper solution, then ethanol was added for washing, and the product C was obtained after multiple centrifugations;

[0069] Step four, the product C is dried at 60 °C for 12 h and ground, sieved, and finally the average particle size of the supramolecular material diverting agent is 0.3 cm.

[0070] Example 4: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0071] Step one, 10 g of starch and cellulose powder are put into a 300 g mixed solution of distilled water and acetone, and stirred at room temperature for 30 min to obtain reaction liquid A;

[0072] Step two, 0.1 g of sodium bisulfite and sodium dodecyl sulfate is added to the reaction liquid A, and ultrasonic treatment is carried out at 40 kHz for 2 h at room temperature to obtain reaction liquid B;

[0073] Step three, the reaction liquid B is first centrifuged at 5000 rpm / min to remove the upper solution, then ethanol is added for washing, and after multiple centrifugations, product C is obtained;

[0074] Step four, the product C is dried at 60 °C for 12 h and ground, sieved, and finally the average particle size of the supramolecular material diverting agent is 100 μm.

[0075] Example 5: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0076] Step one, 10 g of starch and polyethylene glycol powder are put into a 200 g mixed solution of distilled water and toluene, and stirred at room temperature for 30 min to obtain reaction liquid A;

[0077] Step two, 0.1 g of sodium sulfite, amino silane and sodium cetyl sulfate is added to the reaction liquid A, and ultrasonic treatment is carried out at 40 kHz for 2 h at room temperature to obtain reaction liquid B;

[0078] Step three, the reaction liquid B is first centrifuged at 4000 rpm / min to remove the upper solution, then propanol is added for washing, and after multiple centrifugations, product C is obtained;

[0079] Step four, the product C is dried at 80 °C for 12 h and ground, sieved, and finally the average particle size of the supramolecular material diverting agent is 500 μm.

[0080] Example 6: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0081] Step one, 10 g of polybutylene terephthalate and cellulose powder are put into a 500 g mixed solution of distilled water and chloroform, and stirred at room temperature for 30 min to obtain reaction liquid A;

[0082] Step two, 0.1 g of amino silane and sodium dodecyl sulfate is added to the reaction liquid A, and ultrasonic treatment is carried out at room temperature for 2 h to obtain reaction liquid B;

[0083] Step three, the reaction liquid B is first centrifuged at 2000 rpm / min to remove the upper solution, then N-methyl pyrrolidone is added for washing, and after multiple centrifugations, product C is obtained;

[0084] Step four, the product C is dried at 60°C for 12 h and ground, and sieved, and finally the average particle size of the supramolecular material diverting agent is 800 μm.

[0085] Example 7: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, which comprises the following steps:

[0086] Step one, 10 g of polybutylene terephthalate, cellulose and starch powder are put into 300 g of distilled water, and stirring is carried out at room temperature for 30 min to obtain reaction liquid A;

[0087] Step two, 0.1 g of sodium sulfite, amino silane and sodium dodecyl sulfate is added to the reaction liquid A, and ultrasonic treatment is carried out at room temperature for 2 h to obtain reaction liquid B;

[0088] Step three, the reaction liquid B is first centrifuged at 3000 rpm / min to remove the upper solution, then ethanol is added for washing, and after multiple centrifugations, product C is obtained;

[0089] Step four, the product C is dried at 80°C for 12 h and ground, and sieved, and finally the average particle size of the supramolecular material diverting agent is 500 nm.

[0090] Example 8: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, which comprises the following steps:

[0091] Step one, 10 g of polybutylene terephthalate, polyethylene glycol, cellulose and starch powder are put into 1000 g of distilled water, and stirring is carried out at room temperature for 30 min to obtain reaction liquid A;

[0092] Step two, 0.1 g of sodium sulfite, amino silane and sodium dodecyl sulfate is added to the reaction liquid A, and ultrasonic treatment is carried out at room temperature for 2 h to obtain reaction liquid B;

[0093] Step three, the reaction liquid B is first centrifuged at 3000 rpm / min to remove the upper solution, then ethanol is added for washing, and after multiple centrifugations, product C is obtained;

[0094] Step four, the product C is dried at 60°C for 12h and ground, sieved, and finally the supramolecular material diverting agent with an average particle size of 800nm is obtained.

[0095] Example 9: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0096] Step one, 10g of polyethylene terephthalate and starch powder are put into 500g of distilled water, and stirred at room temperature for 30min to obtain reaction liquid A;

[0097] Step two, 0.1g of sodium thiosulfate, amino silane and sodium dodecyl sulfate are added to the reaction liquid A, and ultrasonic treatment is carried out at room temperature for 6h to obtain reaction liquid B;

[0098] The initiator can also be a peroxide and an azo compound, the peroxide is benzoic acid peroxide, diphenyl peroxide or tert-butyl peroxide; the azo compound is azobis isobutyronitrile, azodicarboxamide or azodicarboxylate.

[0099] Step three, the reaction liquid B is first centrifuged at 6000rpm / min to remove the upper solution, then ethanol is added for washing, and after multiple centrifugations, the product C is obtained;

[0100] Step four, the product C is dried at 60°C for 12h and ground, sieved, and finally the supramolecular material diverting agent with an average particle size of 700nm is obtained.

[0101] Example 10: a preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0102] Step one, 50g of polypropylene glycol and polysaccharide powder are put into 500g of distilled water, and stirred at room temperature for 30min to obtain reaction liquid A;

[0103] Step two, 0.1g of methacryloyloxy silane, ammonium sulfate and lecithin are added to the reaction liquid A, and ultrasonic treatment is carried out at room temperature for 2h to obtain reaction liquid B;

[0104] Step three, the reaction liquid B is first centrifuged at 6000rpm / min to remove the upper solution, then dimethyl sulfoxide is added for washing, and after multiple centrifugations, the product C is obtained;

[0105] Step four, the product C is dried at 60°C for 12h and ground, sieved, and finally the supramolecular material diverting agent with an average particle size of 500nm is obtained.

[0106] Example 11: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0107] Step one, 1 g of poly-p-phenylene ether powder was put into 50 g of distilled water, and stirred at room temperature for 30 min to obtain reaction liquid A;

[0108] Step two, 0.1 g of methacryloyloxy silane was added to reaction liquid A, and ultrasonic treatment was carried out at 40 kHz for 2 h at room temperature to obtain reaction liquid B;

[0109] Step three, reaction liquid B was first centrifuged at 6000 rpm / min to remove the upper solution, then N,N-dimethylformamide was added for washing, and product C was obtained after multiple centrifugations;

[0110] Step four, product C was dried at 60°C for 12 h and ground, and sieved, and finally a supramolecular material diverting agent with an average particle size of 200 nm was obtained.

[0111] Example 12: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0112] Step one, 1 g of poly-p-phenylene ether and polyvinyl acetate powder was put into 50 g of distilled water, and stirred at 80°C for 30 min to obtain reaction liquid A;

[0113] Step two, 0.1 g of sodium hydroxide was added to reaction liquid A, and ultrasonic treatment was carried out at 40 kHz for 2 h at room temperature to obtain reaction liquid B;

[0114] Step three, reaction liquid B was first centrifuged at 6000 rpm / min to remove the upper solution, then water was added for washing, and product C was obtained after multiple centrifugations;

[0115] Step four, product C was dried at 60°C for 12 h and ground, and sieved, and finally a supramolecular material diverting agent with an average particle size of 200 nm was obtained.

[0116] Example 13: A preparation method of a supramolecular material diverting agent for hydraulic fracturing is given, comprising the following steps:

[0117] Step one, 1 g of polyvinyl acetate powder was put into 50 g of distilled water and ethanol, and stirred at 80°C for 30 min to obtain reaction liquid A;

[0118] Step two, 0.1 g of sodium hydroxide was added to reaction liquid A, and ultrasonic treatment was carried out at 40 kHz for 2 h at room temperature to obtain reaction liquid B;

[0119] Step three, centrifugal treatment of reaction liquid B at 6000 rpm / min to remove the upper solution, then water is added for washing, and the product C is obtained after multiple centrifugation;

[0120] Step four, drying treatment of product C at 100℃ for 6h and grinding, sieving, finally obtaining the supramolecular material diverting agent with an average particle size of 200nm.

[0121] Test part of example 1:

[0122] 1. Static swelling test

[0123] 1g of the supramolecular material diverting agent prepared in example 1 is weighed and put into 400mL of distilled water to test its static swelling rate at 30℃, and the test results are shown in Figure 1 As the test time is prolonged, the remaining rate shows a gradually decreasing trend, and tends to 0 at about 35h, indicating that the diverting agent completes self-degradation at 35h; the swelling rate shows a trend of first increasing and then decreasing, which embodies the self-crosslinking characteristics of the diverting agent under thermal activation.

[0124] 1g of the supramolecular material diverting agent prepared in example 1 is weighed and put into 400mL of distilled water to test its static swelling rate at 50℃, and the test results are shown in Figure 2 Compared with 30℃, at 50℃, the self-crosslinking swelling and degradation process of the diverting agent is accelerated, and the self-degradation is completed at 24h.

[0125] 1g of the supramolecular material diverting agent prepared in example 1 is weighed and put into 400mL of distilled water to test its static swelling rate at 55℃, and the test results are shown in Figure 3 As the temperature is further increased, the diverting agent completes self-degradation at 7h.

[0126] 1g of the supramolecular material diverting agent prepared in example 1 and 0.1g of boric acid are weighed and put into 400mL of distilled water to test its static swelling rate at 50℃, and the test results are shown in Figure 4 As boric acid is added, the swelling and degradation rate of the diverting agent is accelerated, and the self-degradation is completed at 15h, which is 9h faster than that without boric acid.

[0127] The above results show that the supramolecular material diverting agent prepared in example 1 has the characteristics of thermal activation, self-crosslinking and self-degradation, and the degradation rate can reach 100%. In addition, by adding boric acid, it is verified that it has the characteristics of on-demand plug removal, and in actual use, the plugging time of the diverting agent can be flexibly controlled.

[0128] 2. Dynamic filtration test

[0129] The 1 g of the supermolecular material diversion agent prepared in Example 1 was put into 400 mL of distilled water, and the dynamic filtration loss thereof at 30°C and 50°C was tested respectively to evaluate the plugging performance thereof, and the test results are shown in Figure 5 It can be seen that at 30°C, the filtration loss is about 45 mL, effective plugging is achieved at 45 min, and the effective plugging duration is 13 h. As the temperature rises to 50°C, the filtration loss decreases to 20 mL, effective plugging is achieved at 35 min, and the effective plugging duration is 5 h; after the addition of boric acid, the filtration loss further decreases to 7 mL, effective plugging is achieved at 12 min, and the effective plugging duration is 2 h. The test results further prove the temperature-dependent self-crosslinking and self-degradation characteristics of the diversion agent, and prove that the diversion agent prepared in Example 1 has the temporary plugging performance, and the temporary plugging duration thereof can be flexibly controlled.

[0130] The 1 g of the supermolecular material diversion agent prepared in Example 1 was put into 400 mL of distilled water, and the dynamic filtration loss thereof at 55°C was tested to evaluate the plugging performance thereof, and the test results are shown in Figure 6 It can be seen that at 55°C, the filtration loss gradually increases with the extension of time, and the filtration loss approaches 400 mL within 40 min, indicating that the diversion agent does not have the plugging performance at this temperature.

[0131] In summary, the diversion agent prepared in Example 1 has a temperature window of 30-50°C.

[0132] Example 2 Test Part:

[0133] 1. Static swelling test

[0134] The 1 g of the supermolecular material diversion agent prepared in Example 2 was put into 400 mL of distilled water, and the static swelling rate thereof at 70°C was tested, and the test results are shown in Figure 7 As the test time extends to 170 h, the remaining rate and the swelling rate remain at a relatively high level and are relatively stable, indicating that the diversion agent has high stability at 70°C.

[0135] The 1 g of the supermolecular material diversion agent prepared in Example 2 was put into 400 mL of distilled water, and the static swelling rate thereof at 75°C was tested, and the test results are shown in Figure 8 Compared with 70°C, at 75°C, the diversion agent undergoes a significant self-crosslinking swelling and degradation process, and the self-degradation is completed at 70 h.

[0136] The 1 g of the supermolecular material diversion agent prepared in Example 2 was put into 400 mL of distilled water, and the static swelling rate thereof at 80°C was tested, and the test results are shown in Figure 9 Due to the increase in temperature, the diversion agent completes the self-degradation at 48 h.

[0137] The supermolecular material of 1 g prepared in Example 2 was weighed and put into 400 mL distilled water to test its static swelling rate at 85°C, and the test results are shown in Figure 10 As the temperature was further increased, the diverting agent completed self-degradation in 30 h.

[0138] The supermolecular material of 1 g prepared in Example 2 was weighed and put into 400 mL distilled water to test its static swelling rate at 90°C, and the test results are shown in Figure 11 It can be seen that the diverting agent completed self-degradation in 8 h.

[0139] The supermolecular material of 1 g prepared in Example 2 and boric acid of 0.1 g were weighed and put into 400 mL distilled water to test its static swelling rate at 70°C, and the test results are shown in Figure 12 Due to the addition of boric acid, the swelling and degradation rate of the diverting agent was accelerated, and the self-degradation was completed in 96 h, which was 74 h faster than that without boric acid.

[0140] Thanks to the higher polymerization degree, the supermolecular material prepared in Example 2 has higher thermal stability, and at a lower temperature, the degradation speed thereof can be accelerated by adjusting the pH value of the fracturing fluid. The pH value of the fracturing fluid is adjusted to 3-6 by adding one or more of phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid to accelerate the degradation time of the diverting agent.

[0141] The supermolecular material of 1 g prepared in Example 2 was weighed and put into 400 mL distilled water to test its dynamic filtration loss at 70°C to evaluate its plugging performance, and the test results are shown in Figure 13 It can be seen that due to the higher thermal stability of the diverting agent, the filtration loss gradually increased with time at 70°C, which is consistent with the static swelling test results, indicating that it does not have plugging performance.

[0142] The supermolecular material of 1 g prepared in Example 2 was weighed and put into 400 mL distilled water to test its dynamic filtration loss at 70°C, 75°C, 80°C and 85°C (for 70°C, 0.1 boric acid was added) to evaluate its plugging performance, and the test results are shown in Figure 14It can be seen that at 70℃, the filtration loss is about 15 mL due to the addition of boric acid, effective plugging is achieved at 1.5 h, and the effective plugging duration is 8 h. As the temperature rises to 75℃, the filtration loss is 47 mL, effective plugging is achieved at 40 min, and the effective plugging duration is 25 h; as the temperature rises to 80℃, the filtration loss is 21 mL, effective plugging is achieved at 24 min, and the effective plugging duration is 4 h. As the temperature rises to 85℃, the filtration loss is 7 mL, effective plugging is achieved at 12 min, and the effective plugging duration is 3 h. The test results further prove that the diverting agent prepared in Example 2 has higher thermal stability, and at the same time prove that the diverting agent prepared in Example 2 has temporary plugging performance, and the temporary plugging duration thereof can be flexibly controlled.

[0143] The supermolecular material diverting agent 1 g prepared in Example 2 was weighed into 400 mL of distilled water, and the dynamic filtration loss thereof at 90℃ was tested to evaluate the plugging performance thereof, and the test results are shown in Figure 15 It can be seen that at 90℃, the filtration loss gradually increases with the extension of time, and the filtration loss approaches 400 mL within 27 min, indicating that the diverting agent does not have plugging performance at this temperature. The diverting agent prepared in Example 2 has a suitable temperature window of 70-85℃.

[0144] Example 3 Test Part:

[0145] 1. Static swelling test

[0146] The supermolecular material diverting agent 1 g prepared in Example 3 was weighed into 400 mL of distilled water, and the static swelling rate thereof at 30℃ was tested, and the test results are shown in Figure 16 As the test time extends to 170 h, the remaining rate and the swelling rate remain at a relatively high level and are relatively stable.

[0147] The supermolecular material diverting agent 1 g prepared in Example 3 was weighed into 400 mL of distilled water, and the static swelling rate thereof at 70℃ was tested, and the test results are shown in Figure 17 Compared with 30℃, the swelling rate and the remaining rate of the diverting agent at 70℃ do not change significantly. The above test results show that the diverting agent has higher stability at 30℃-70℃.

[0148] 2. Dynamic filtration test

[0149] The supermolecular material diverting agent 1 g prepared in Example 3 was weighed into 400 mL of distilled water, and the dynamic filtration loss thereof at 30℃ was tested to evaluate the plugging performance thereof, and the test results are shown in Figure 18Figure (a) can be seen, due to the higher thermal stability of the diverting agent, at 30°C, the fluid loss reaches a maximum value of 45 mL at 1 h, then remains essentially unchanged and continues to 240 h, indicating that it has long-term even permanent plugging performance. Figure (b) and Figure (c) show the front view and top view of the diverting agent particles taken out after 240 h, respectively, as shown in Figure 20 It can be seen that the diverting agent particles self-crosslink closely together to form a columnar shape, which intuitively shows its plugging characteristics. After drying, the residual rate is tested to be 99%, which further proves its long-term plugging performance.

[0150] The supermolecular material diverting agent 1 g prepared in Example 3 was weighed and put into 400 mL distilled water, and its dynamic fluid loss at 70°C was tested to evaluate its plugging performance, and the test results are shown in Figure 19 It can be seen that, compared with 30°C, at 70°C, the plugging time is faster, the fluid loss reaches a maximum value of only 2.5 mL at 0.5 h, then remains essentially unchanged and continues to 240 h, indicating that it has long-term even permanent plugging performance. Figure 19 and Figure 19 respectively show the front view and top view of the diverting agent particles taken out after 240 h, respectively, it can be seen that the diverting agent particles self-crosslink closely together to form a columnar shape, which intuitively shows its plugging characteristics. After drying, the residual rate is tested to be 99%, which further proves its long-term plugging performance.

[0151] In summary, the diverting agent prepared in Example 3 has long-term even permanent plugging performance, and the applicable temperature window is 30-70°C.

Claims

1. A method for the preparation of a supramolecular material diverting agent for hydraulic fracturing, characterized by The method comprises the following steps: Step one, disperse the polymer powder into solvent, stir to obtain reaction liquid A; Step two, add initiator to reaction liquid A according to initiator and polymer powder mass ratio 1:(10-500), and ultrasonic treatment to obtain reaction liquid B; the polymer powder is one or more of polyester polymer, polyether polymer and natural polymer; the initiator is one or more of peroxide, azo compound, hydroxide, silane coupling agent, sulfate, sulfite and surfactant; the silane coupling agent is vinyl silane, amino silane or methacryloyloxy silane; the sulfate and sulfite are ammonium sulfate, sodium thiosulfate or sodium bisulfite; the surfactant is sodium dodecyl benzene sulfonate, lecithin, sodium dodecyl sulfate or sodium cetyl sulfate; Step three, centrifugal treatment is firstly performed on reaction liquid B to remove the upper solution, then washing is performed, and product C is obtained after multiple centrifugal treatments; Step four, dry and grind product C, and sieve to obtain supermolecular material diverting agent with different particle sizes.

2. The method for preparing the supramolecular material diverting agent for hydraulic fracturing according to claim 1, characterized in that: The solvent is one or more of water, methanol, ethanol, acetone, toluene and chloroform; the stirring temperature is room temperature-100 DEG C; and the stirring time is 30 min-48 h.

3. The method of claim 1, wherein the method is characterized by: The polyester polymer is polyvinyl acetate, polyethylene terephthalate or polybutylene terephthalate; the polyether polymer is polyethylene glycol, polypropylene glycol or poly-p-phenylene ether; and the natural polymer is cellulose, polysaccharide or starch.

4. The method of claim 1, wherein the method is characterized by: The peroxide is hydrogen peroxide, benzoic acid peroxide, diphenyl peroxide or tert-butyl peroxide; the azo compound is azobis isobutyronitrile, azodicarboxamide or azodicarboxylate; and the hydroxide is sodium hydroxide or potassium hydroxide.

5. The method of claim 1, wherein the method is characterized by: The ultrasonic treatment frequency in step two is 20-40 kHz; the ultrasonic time is 2-8 h; the centrifugal speed in step three is 2000-6000 rpm / min; and the drying temperature in step four is 60-100 DEG C.

6. The method of claim 1, wherein the method is characterized by: The reagent used for washing in step three is one or more of water, methanol, ethanol, propanol, dimethyl sulfoxide, N,N-dimethyl formamide and N-methyl pyrrolidone.

7. A supramolecular material diverting agent for hydraulic fracturing prepared according to the method of any one of claims 1-6, characterized by: The particle size range is 200 nm-2 cm.

8. The application of the supermolecular material diverting agent for hydraulic fracturing in claim 7 in the hydraulic fracturing technology of oil and gas field.

9. Use of the supramolecular material diverting agent for hydraulic fracturing according to claim 8 in the technology of hydraulic fracturing of oil and gas fields, characterized by the fact that: The degradation time of the diverting agent is accelerated by adjusting the pH value of the fracturing fluid to 3-6.

10. Use of the supramolecular material diverting agent for hydraulic fracturing according to claim 9 in the technology of hydraulic fracturing of oil and gas fields, characterized by the fact that: The pH value of the fracturing fluid is adjusted by adding one or more of boric acid, phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid.

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