Supramolecular material diverting agent for hydraulic fracturing as well as preparation method and application of supramolecular material diverting agent

Abstract

The invention discloses a supramolecular material diverting agent for hydraulic fracturing as well as a preparation method and application of the supramolecular material diverting agent, a raw material polymer is changed into a novel copolymer from an oligomer by adding an initiator, the surface chemical property of an intrinsic material is changed, and the supramolecular material diverting agent has better temperature resistance, is suitable for the oil reservoir temperature of 30-150 DEG C and is wide in use temperature range; the temporary plugging agent has a self-crosslinking characteristic through environmental thermal activation, and compared with a physically stacked temporary plugging agent material, the temporary plugging agent has better plugging performance due to the chemical crosslinking characteristic; in addition, the supramolecular material also has a self-degradation characteristic, the degradation process can be accelerated by adjusting the pH value of the fracturing fluid, and blockage removal as required can be realized; the thermal stability of the supramolecular material diverting agent is adjusted by controlling the polymerization degree, and the supramolecular material diverting agent has both temporary plugging and long-acting plugging properties and is wide in application range.

Description

Technical Field

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

[0002] my country has a large number of unconventional oil and gas resources. 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. Fracturing fluid is injected through a ground high-pressure pump to break the rock formation and generate cracks that extend to the oil and gas reservoir, thereby conducting exploitation. Affected by the heterogeneity of the reservoir and the closure stress of the formation, hydraulic fracturing cracks often expand unevenly, which not only causes a waste of resources, but also seriously affects oil and gas production. Therefore, in the process of implementing hydraulic fracturing, how to achieve uniform expansion of reservoir cracks is crucial to increasing the production and efficiency of oil and gas resources.

[0003] The fracturing fluid containing the diverter is injected through the surface pump. The diverter "effectively" blocks the initial cracks or perforations in the formation, forming an out-of-crack blockage, which causes the wellbore pressure or the net pressure in the crack to continue to rise, so that the subsequent fracturing fluid is transferred to a position outside the initial crack orientation. In addition, the diverter also has the function of blocking the main crack in the crack, opening new branch cracks or activating natural cracks, and even multiple diversions, which greatly improves the uniform expansion of the cracks. In order to improve the fluidity of oil and gas to achieve the effect of increasing production, the diverter must be unblocked within the specified time and efficiently return. This time-effective diverter is also called a temporary plugging agent. In addition, with the continuous advancement of oil and gas production construction, the heterogeneity of the reservoir has led to a decrease in oil and gas production in some fracturing areas. In order to improve the oil and gas recovery rate, secondary or multiple fracturing is required. Therefore, it is very necessary to implement long-term plugging in the fracturing area with low oil and gas production. With the implementation of the policy of green development of oil fields, it is urgent to develop a low-toxic, low-cost diverter with both temporary plugging and long-term plugging performance.

[0004] Supramolecular materials are considered to be good candidates for temporary plugging agents. They not only have low toxicity, but also have heat-activated self-crosslinking properties. When injected into the formation, no other materials (crosslinking agents, destroyers, etc.) need to be added. As the temperature rises, the material will gradually form a gel. These gels have the characteristics of high viscosity and high compressive strength, and can easily plug the cracks. If the temperature rises further, the gel will break, return to liquid state, and easily flow back, thereby restoring the production capacity of the cracks, and theoretically 100% removal can be achieved. However, the plugging performance of supramolecular materials currently used for diverters, such as polylactic acid and butene glycol vinyl alcohol copolymer, is strongly related to temperature. Studies have shown that polylactic acid takes 10 days to achieve 74% degradation at 80°C, while it only takes 10 hours to complete 100% degradation at 120°C. In addition, in the low temperature zone, the applicable temperature of butene glycol vinyl alcohol copolymer can be as low as 26°C, but the temporary plugging performance is greatly reduced in the medium and high temperature zones. These temporary plugging agents not only have different applicable temperature ranges, but also cannot be unblocked on demand, which increases their use cost and limits their development.

[0005] The Chinese patent (CN118496837A) grafts carboxymethyl chitosan onto allyl glycidyl ether, and then obtains a network structure polymer by copolymerization and cross-linking; then, it is blended with polylactic acid to prepare modified polymer microspheres. Although this modified polymer microsphere can achieve on-demand unblocking, the process is relatively complicated and the applicable temperature range is narrow (80-100°C), which is not conducive to promotion and use. The Chinese patent (CN118146775A) discloses a double-cross-linked thermal phase change gel temporary plugging agent, which is applied to oil and gas reservoirs with a temperature of 100-150°C, can automatically gel and degrade, and the filtration loss before gelation is low. However, this temporary plugging agent has complex ingredients, high cost, and cannot be applied to medium and low temperature oil and gas reservoirs. The US patent (US11053427B2) provides a low-density, high-strength, degradable temporary plugging agent with an applicable temperature of 30-90°C, but it cannot be unblocked on demand. Therefore, developing a supramolecular material diverting agent with a wide operating temperature range and controllable plugging and unplugging time will help promote the green development of oil fields and has broad market prospects. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a supramolecular material diverter for hydraulic fracturing and a preparation method and application thereof. The prepared supramolecular material diverter has heat-activated self-crosslinking and self-degradation properties, controllable plugging time, a wide applicable temperature range, and long-term plugging capability.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for preparing a supramolecular material diverting agent for hydraulic fracturing comprises the following steps:

[0009] Step 1, dispersing polymer powder into a solvent and stirring evenly to obtain a reaction solution A;

[0010] Step 2, adding an initiator to a reaction solution A at a mass ratio of initiator to polymer powder of 1:(10-500), and ultrasonically treating to obtain a reaction solution B; the polymer powder is one or more of a polyester polymer, a polyether polymer and a natural polymer; the initiator is one or more of a peroxide, an azo compound, a hydroxide, a silane coupling agent, a sulfate, a sulfite and a surfactant;

[0011] Step 3, the reaction solution B is first centrifuged to remove the upper solution, and then washed, and product C is obtained after multiple centrifugations;

[0012] Step 4: drying and grinding the product C, and sieving it to finally obtain supramolecular material diverting agents with different particle sizes.

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

[0014] Preferably, the polyester polymer is polyvinyl acetate, polyethylene terephthalate or polybutylene terephthalate; the polyether polymer is polyethylene glycol, polypropylene glycol or polyphenylene methyl 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 azodicarboxylate; the hydroxide is sodium hydroxide or potassium hydroxide; the silane coupling agent is vinyl silane, aminosilane or methacryloxysilane; the sulfate and sulfite are ammonium sulfate, sodium thiosulfate or sodium bisulfite; the surfactant is sodium dodecylbenzene sulfonate, lecithin, sodium dodecyl sulfate or sodium hexadecyl sulfate.

[0016] Preferably, the frequency of the ultrasonic treatment in step 2 is 20-40kHz; the ultrasonic time is 2-8h; the centrifugal speed in step 3 is 2000-6000rpm / min; and the drying temperature in step 4 is 60-100°C.

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

[0018] The invention also provides a supramolecular material diverting agent for hydraulic fracturing, with a particle size ranging from 200nm to 2cm.

[0019] The present invention also provides an application of a 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 present invention has the following beneficial effects:

[0023] (1) The supramolecular material diverting agent prepared by the present invention is changed from a oligomer to a new copolymer by adding an initiator, thereby changing the surface chemical properties of the intrinsic material and having better temperature resistance. The thermal stability can be further adjusted by adjusting the degree of polymerization of the product. Tests have found that the supramolecular material prepared by the present invention is suitable for reservoir temperatures of 30-150°C and has a wide range of operating temperatures. It has the characteristics of self-crosslinking and self-degradation through environmental heat activation.

[0024] (2) The plugging time of the supramolecular material diverter prepared by the present invention is controllable. The degradation process can be accelerated by adjusting the pH of the fracturing fluid. Under acidic conditions, the hydroxyl groups on the surface of the diverter are passivated and easily form a cross-linked structure to form a plug. As the service time increases, it is affected by protonation, and its molecular chain breaks, the degree of hydrolysis continues to deepen, and the mechanical properties decrease, so it loses its plugging ability and gradually returns to a liquid state. Therefore, the degradation rate can be accelerated to achieve the purpose of controllable plugging time.

[0025] (3) The supramolecular material diverter prepared by the present invention has both temporary plugging and long-term plugging performance. In addition to unblocking as needed, as the fracturing construction continues, after multiple fracturing operations, many low-productivity "waste" cracks are generated due to the heterogeneity of the reservoir. In order not to affect the recovery rate of the oil and gas field, it is necessary to perform long-term or even permanent plugging on them. The diverter has good temperature resistance and thus has the ability of long-term plugging and a wide range of applications.

[0026] (4) The particle size of the supramolecular material diverter prepared by the present invention is controllable, and can be customized and used in combination according to the size of microcracks, so as to achieve dual plugging effects both outside and inside the cracks. Large particle materials are used to plug the main cracks to form plugging outside the cracks; small particle materials are used to plug the branch cracks inside the main cracks, and multiple diversion plugging is performed to improve the uniform expansion of the cracks.

[0027] (5) The chemical reagents used in the present invention are low in toxicity and are green and environmentally friendly; and the method has low equipment requirements, high yield, and a simple process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a static swelling test result diagram of the diverting agent prepared in Example 1 of the present invention at 30°C;

[0029] Figure 2 This is a static swelling test result diagram of the diverting agent prepared in Example 1 of the present invention at 50°C;

[0030] Figure 3 This is a static swelling test result diagram of the diverting agent prepared in Example 1 of the present invention at 55°C;

[0031] Figure 4 This is a static swelling test result diagram of the diverting agent prepared in Example 1 of the present invention when boric acid is added at 50°C;

[0032] Figure 5 The dynamic filtration loss graph of the diverting agent prepared in Example 1 of the present invention at 30°C and 50°C;

[0033] Figure 6 This is a dynamic filtration loss graph of the diverting agent prepared in Example 1 of the present invention at 55°C;

[0034] Figure 7 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention at 70°C;

[0035] Figure 8 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention at 75°C;

[0036] Fig. 9 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention at 80°C;

[0037] Fig.10 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention at 85°C;

[0038] Fig.11 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention at 90°C;

[0039] Fig.12 This is a static swelling test result diagram of the diverting agent prepared in Example 2 of the present invention when boric acid is added at 70°C;

[0040] Fig.13 This is a dynamic filtration loss graph of the diverting agent prepared in Example 2 of the present invention at 70°C;

[0041] Fig.14 The dynamic filtration loss graph of the diverting agent prepared in Example 2 of the present invention at 70°C, 75°C, 80°C and 85°C;

[0042] Fig.15This is a dynamic filtration loss graph of the diverting agent prepared in Example 2 of the present invention at 90°C;

[0043] Fig.16 This is a static swelling test result diagram of the diverting agent prepared in Example 3 of the present invention at 30°C;

[0044] Fig.17 This is a static swelling test result diagram of the diverting agent prepared in Example 3 of the present invention at 70°C;

[0045] Fig.18 This is a view of the diverting agent prepared in Example 3 of the present invention at 30°C;

[0046] Wherein, (a) is a dynamic filtration loss graph of the diverting agent prepared in Example 3 of the present invention at 30°C;

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

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

[0049] Fig.19 Dynamic view of the diverting agent prepared in Example 3 of the present invention at 70°C

[0050] Wherein, (a) is a dynamic filtration loss graph of the diverting agent prepared in Example 3 of the present invention at 70°C;

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

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

[0053] Fig. 20 Schematic diagram of the close stacking of diverter particles into self-crosslinking. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0055] Example 1: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0056] Step 1: Add 10 g of starch and polyvinyl acetate powder into 100 g of distilled water, and stir at 60° C. for 30 min to obtain a reaction solution A;

[0057] Step 2, adding 0.1 g of hydrogen peroxide, vinyl silane and sodium dodecylbenzene sulfonate to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0058] Step 3, the reaction solution B is first centrifuged at 2000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0059] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 0.5 cm.

[0060] Example 2: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0061] Step 1: put 10 g of cellulose powder and polyethylene terephthalate into 100 g of distilled water and ethanol, and stir at room temperature for 2 h to obtain reaction solution A;

[0062] Step 2, adding 0.1 g of methacryloxysilane, sodium thiosulfate and lecithin to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0063] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then methanol is added for washing, and product C is obtained after multiple centrifugations;

[0064] Step 4: drying the product C at 80° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 0.1 cm.

[0065] Example 3: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0066] Step 1: put 10 g of starch powder into a mixed solution of 200 g of distilled water and methanol, and stir at room temperature for 30 min to obtain a reaction solution A;

[0067] Step 2, adding 0.1 g of vinyl silane, sodium dodecylbenzene sulfonate and sodium sulfite to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0068] Step 3, the reaction solution B is first centrifuged at 4000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0069] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 0.3 cm.

[0070] Example 4: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0071] Step 1: put 10g starch and cellulose powder into a mixed solution of 300g distilled water and acetone, and stir at room temperature for 30min to obtain a reaction solution A;

[0072] Step 2, adding 0.1 g of sodium bisulfite and sodium dodecyl sulfate to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0073] Step 3, the reaction solution B is first centrifuged at 5000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0074] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 100 μm.

[0075] Example 5: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0076] Step 1: Add 10 g of starch and polyethylene glycol powder into a mixed solution of 200 g of distilled water and toluene, and stir for 30 min at room temperature to obtain a reaction solution A;

[0077] Step 2, adding 0.1 g of sodium sulfite, aminosilane and sodium hexadecyl sulfate to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0078] Step 3, the reaction solution B is first centrifuged at 4000 rpm / min to remove the upper solution, and then propanol is added for washing, and product C is obtained after multiple centrifugations;

[0079] Step 4: drying the product C at 80° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 500 μm.

[0080] Example 6: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0081] Step 1: put 10 g of polybutylene terephthalate and cellulose powder into a mixed solution of 500 g of distilled water and chloroform, and stir at room temperature for 30 min to obtain a reaction solution A;

[0082] Step 2, adding 0.1 g of aminosilane and sodium hexadecyl sulfate to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0083] Step 3, the reaction solution B is first centrifuged at 2000 rpm / min to remove the upper solution, and then N-methylpyrrolidone is added for washing, and product C is obtained after multiple centrifugations;

[0084] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 800 μm.

[0085] Example 7: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0086] Step 1: put 10 g of polybutylene terephthalate, cellulose and starch powder into 300 g of distilled water, and stir for 30 min at room temperature to obtain reaction solution A;

[0087] Step 2, adding 0.1 g of sodium sulfite, aminosilane and sodium hexadecyl sulfate to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0088] Step 3, the reaction solution B is first centrifuged at 3000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0089] Step 4: drying the product C at 80° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 500 nm.

[0090] Example 8: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0091] Step 1: put 10 g of polybutylene terephthalate, polyethylene glycol, cellulose and starch powder into 1000 g of distilled water, and stir at room temperature for 30 min to obtain reaction solution A;

[0092] Step 2, adding 0.1 g of sodium sulfite, aminosilane and sodium dodecyl sulfate to reaction solution A, and ultrasonically treating at 20 kHz for 8 h at room temperature to obtain reaction solution B;

[0093] Step 3, the reaction solution B is first centrifuged at 3000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0094] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 800 nm.

[0095] Example 9: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0096] Step 1: Add 10 g of polyethylene terephthalate and starch powder into 500 g of distilled water and stir for 30 min at room temperature to obtain a reaction solution A;

[0097] Step 2, adding 0.1 g of sodium thiosulfate, aminosilane and sodium dodecyl sulfate to reaction solution A, and ultrasonically treating at 30 kHz for 6 h at room temperature to obtain reaction solution B;

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

[0099] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then ethanol is added for washing, and product C is obtained after multiple centrifugations;

[0100] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 700 nm.

[0101] Example 10: A method for preparing a supramolecular material diverting agent for hydraulic fracturing is provided, comprising the following steps:

[0102] Step 1: Add 50 g of polypropylene glycol and polysaccharide powder into 500 g of distilled water and stir for 30 min at room temperature to obtain reaction solution A;

[0103] Step 2, adding 0.1 g of methacryloxysilane, ammonium sulfate and lecithin to reaction solution A, and subjecting the mixture to ultrasonic treatment at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0104] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then dimethyl sulfoxide is added for washing, and product C is obtained after multiple centrifugations;

[0105] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 500 nm.

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

[0107] Step 1: Add 1 g of poly(p-phenylene dimethyl ether) powder into 50 g of distilled water and stir for 30 min at room temperature to obtain a reaction solution A;

[0108] Step 2, adding 0.1 g of methacryloxysilane to reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain reaction solution B;

[0109] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then N,N-dimethylformamide is added for washing, and product C is obtained after multiple centrifugations;

[0110] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 200 nm.

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

[0112] Step 1: Add 1 g of poly(p-phenylene dimethyl ether) and poly(vinyl acetate) powder into 50 g of distilled water and stir at 80° C. for 30 min to obtain a reaction solution A;

[0113] Step 2, adding 0.1 g of sodium hydroxide to the reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain a reaction solution B;

[0114] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then water is added for washing, and product C is obtained after multiple centrifugations;

[0115] Step 4: drying the product C at 60° C. for 12 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 200 nm.

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

[0117] Step 1: Add 1 g of polyvinyl acetate powder into 50 g of distilled water and ethanol, and stir at 80° C. for 30 min to obtain a reaction solution A;

[0118] Step 2, adding 0.1 g of sodium hydroxide to the reaction solution A, and ultrasonically treating at 40 kHz for 2 h at room temperature to obtain a reaction solution B;

[0119] Step 3, the reaction solution B is first centrifuged at 6000 rpm / min to remove the upper solution, and then water is added for washing, and product C is obtained after multiple centrifugations;

[0120] Step 4: drying the product C at 100° C. for 6 h, grinding it, and sieving it to finally obtain a supramolecular material diverting agent with an average particle size of 200 nm.

[0121] Example 1 Experimental part:

[0122] 1. Static swelling test

[0123] 1 g of the supramolecular material diverting agent prepared in Example 1 was weighed and put into 400 mL of distilled water to test its static swelling rate at 30° C. The test results are as follows: Figure 1 As the test time increases, the residual rate shows a gradual downward trend and approaches 0 at around 35h, indicating that the diverter has completed self-degradation at 35h; the swelling rate shows a trend of first increasing and then decreasing, reflecting the heat-activated self-crosslinking characteristics of the diverter.

[0124] 1 g of the supramolecular material diverting agent prepared in Example 1 was weighed and put into 400 mL of distilled water to test its static swelling rate at 50° C. The test results are as follows: Figure 2 Compared with 30°C, at 50°C, the process of self-crosslinking swelling and degradation of the diverting agent was accelerated, and the self-degradation was completed in 24 hours.

[0125] 1 g of the supramolecular material diverting agent prepared in Example 1 was weighed and put into 400 mL of distilled water to test its static swelling rate at 55°C. The test results are as follows: Figure 3 As the temperature further increased, the diverter completed self-degradation in 7 hours.

[0126] Weigh 1 g of the supramolecular material diverting agent prepared in Example 1 and 0.1 g of boric acid and put them into 400 mL of distilled water to test their static swelling rate at 50° C. The test results are as follows: Figure 4 As shown in the figure, due to the addition of boric acid, the swelling and degradation rate of the diverter agent was accelerated, and the self-degradation was completed at 15h. Compared with the case without adding boric acid, the degradation time was accelerated by 9h.

[0127] The above results show that the supramolecular material diverter prepared in Example 1 has heat-activated self-crosslinking and self-degradation properties, and the degradation rate can reach 100%. In addition, the addition of boric acid verifies that it has the property of unblocking on demand, and in actual use, the blocking time of the diverter can be flexibly controlled.

[0128] 2. Dynamic filtration test

[0129] 1 g of the supramolecular material diverting agent prepared in Example 1 was weighed and put into 400 mL of distilled water, and its dynamic filtration loss at 30°C and 50°C was tested to evaluate its plugging performance. The test results are as follows: Figure 5 As shown. It can be seen that at 30°C, the filtration loss was about 45mL, effective plugging was achieved at 45min, and the effective plugging time was 13h. As the temperature increased to 50°C, the filtration loss decreased to 20mL, effective plugging was achieved at 35min, and the effective plugging time was 5h; after adding boric acid, the filtration loss further decreased to 7mL, effective plugging was achieved at 12min, and the effective plugging time was 2h. The test results further prove that the diverter has a strong correlation with temperature and has self-crosslinking and self-degradation properties, and at the same time prove that the diverter prepared in Example 1 has temporary plugging performance, and its temporary plugging time can be flexibly controlled.

[0130] 1 g of the supramolecular material diverting agent prepared in Example 1 was weighed and put into 400 mL of distilled water, and its dynamic filtration loss at 55°C was tested to evaluate its plugging performance. The test results are as follows: Figure 6 It can be seen that at 55°C, the filtration loss gradually increases with time, and the filtration loss within 40 minutes is close to 400 mL, indicating that the diverter has no plugging performance at this temperature.

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

[0132] Example 2 Experimental part:

[0133] 1. Static swelling test

[0134] 1 g of the supramolecular material diverting agent prepared in Example 2 was weighed and put into 400 mL of distilled water to test its static swelling rate at 70°C. The test results are as follows: Figure 7 As the test time was extended to 170 h, the remaining rate and swelling rate remained at a relatively high level and were relatively stable, indicating that the diverting agent had high stability at 70 °C.

[0135] 1 g of the supramolecular material diverting agent prepared in Example 2 was weighed and put into 400 mL of distilled water to test its static swelling rate at 75°C. The test results are as follows: Figure 8 Compared with 70°C, at 75°C, the diverter agent showed significant self-crosslinking swelling and degradation process, and completed self-degradation at 70h.

[0136] 1 g of the supramolecular material diverting agent prepared in Example 2 was weighed and put into 400 mL of distilled water to test its static swelling rate at 80°C. The test results are as follows: Fig. 9 As shown in Figure 2, due to the increase in temperature, the diverter agent completed self-degradation within 48 hours.

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

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

[0139] Weigh 1 g of the supramolecular material diverting agent prepared in Example 2 and 0.1 g of boric acid and put them into 400 mL of distilled water to test their static swelling rate at 70° C. The test results are as follows: Fig.12 As shown in the figure, due to the addition of boric acid, the swelling and degradation rate of the diverter agent was accelerated, and the self-degradation was completed at 96h. Compared with the case without adding boric acid, the degradation time was accelerated by 74h.

[0140] Thanks to the higher degree of polymerization, the supramolecular material prepared in Example 2 has higher thermal stability. At lower temperatures, its degradation rate can be accelerated by adjusting the pH value of the fracturing fluid. The degradation time of the diverter can be accelerated by adding one or more of phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid to adjust the pH value of the fracturing fluid to 3-6. 2. Dynamic filtration test

[0141] 1 g of the supramolecular material diverting agent prepared in Example 2 was weighed and put into 400 mL of distilled water, and its dynamic filtration loss at 70°C was tested to evaluate its plugging performance. The test results are as follows: Fig.13 As shown in the figure, it can be seen that due to the high thermal stability of the diverter, at 70°C, the filtration loss gradually increases with time, which is consistent with the static swelling test results, indicating that it does not have plugging performance.

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

[0143] 1 g of the supramolecular material diverting agent prepared in Example 2 was weighed and put into 400 mL of distilled water, and its dynamic filtration loss at 90°C was tested to evaluate its plugging performance. The test results are as follows: Fig.15 As shown. It can be seen that at 90°C, the filtration loss gradually increases with time, and the filtration loss in 27 minutes is close to 400 mL, indicating that the diverter has no plugging performance at this temperature. The diverter prepared in Example 2 has an applicable temperature window of 70-85°C.

[0144] Example 3 Experimental part:

[0145] 1. Static swelling test

[0146] 1 g of the supramolecular material diverting agent prepared in Example 3 was weighed and put into 400 mL of distilled water to test its static swelling rate at 30°C. The test results are as follows: Fig.16 As the test time was extended to 170 h, the remaining rate and swelling rate remained at a relatively high level and were relatively stable.

[0147] 1 g of the supramolecular material diverting agent prepared in Example 3 was weighed and put into 400 mL of distilled water to test its static swelling rate at 70°C. The test results are as follows: Fig.17 Compared with 30℃, the swelling rate and residual rate of the diverter at 70℃ do not change significantly. The above test results show that the diverter has high stability at 30℃-70℃.

[0148] 2. Dynamic filtration test

[0149] 1 g of the supramolecular material diverting agent prepared in Example 3 was weighed and put into 400 mL of distilled water to test its dynamic filtration loss at 30°C to evaluate its plugging performance. The test results are as follows: Fig.18As shown in Figure (a), due to the high thermal stability of the diverter, at 30°C, the filtration loss reaches a maximum of 45 mL at 1 hour, and then remains basically unchanged as time goes by and lasts until 240 hours, indicating that it has long-term or even permanent plugging performance. Figures (b) and (c) show the front view and top view of the diverter particles taken out after 240 hours, respectively. Fig. 20 It can be seen that the diverter particles are self-crosslinked and stacked tightly together to form a column, which intuitively shows its plugging characteristics. After drying, the test shows that its residual rate is 99%, which further proves its long-term plugging performance.

[0150] 1 g of the supramolecular material diverting agent prepared in Example 3 was weighed and put into 400 mL of distilled water, and its dynamic filtration loss at 70°C was tested to evaluate its plugging performance. The test results are as follows: Fig.19 As shown in Figure (a), compared with 30°C, at 70°C, the plugging time is faster, and the filtration loss reaches a maximum value of only 2.5mL at 0.5h, and then remains basically unchanged as time goes by and lasts until 240h, indicating that it has long-term or even permanent plugging performance. Fig.19 and Fig.19 The front view and top view of the diverter particles taken out after 240 hours are shown respectively. It can be seen that the diverter particles are self-crosslinked and tightly stacked together to form a column, which intuitively shows its plugging characteristics. After drying, the test shows that its residual rate is 99%, which further proves its long-term plugging performance.

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

Claims

1. A method for preparing a supramolecular material diverting agent for hydraulic fracturing, characterized in that The following steps are involved: Step 1, dispersing polymer powder into a solvent and stirring evenly to obtain a reaction solution A; Step 2, adding an initiator to a reaction solution A at a mass ratio of initiator to polymer powder of 1:(10-500), and ultrasonically treating to obtain a reaction solution B; the polymer powder is one or more of a polyester polymer, a polyether polymer and a natural polymer; the initiator is one or more of a peroxide, an azo compound, a hydroxide, a silane coupling agent, a sulfate, a sulfite and a surfactant; Step 3, the reaction solution B is first centrifuged to remove the upper solution, and then washed, and product C is obtained after multiple centrifugations; Step 4: drying and grinding the product C, and sieving it to finally obtain supramolecular material diverting agents 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° C.; and the stirring time is 30 min-48 h.

3. The method for preparing the supramolecular material diverting agent for hydraulic fracturing according to claim 1, characterized in that: The polyester polymer is polyvinyl acetate, polyethylene terephthalate or polybutylene terephthalate, etc.; the polyether polymer is polyethylene glycol, polypropylene glycol or polyphenylene methyl ether; and the natural polymer is cellulose, polysaccharide or starch.

4. The method for preparing the supramolecular material diverting agent for hydraulic fracturing according to claim 1, characterized in that: The peroxide is hydrogen peroxide, benzoic acid peroxide, diphenyl peroxide or tert-butyl peroxide; the azo compound is azobisisobutyronitrile, azodicarbonamide or azodicarboxylate; the hydroxide is sodium hydroxide or potassium hydroxide; the silane coupling agent is vinyl silane, aminosilane or methacryloxysilane; the sulfate and sulfite are ammonium sulfate, sodium thiosulfate or sodium bisulfite; the surfactant is sodium dodecylbenzene sulfonate, lecithin, sodium dodecyl sulfate or sodium hexadecyl sulfate.

5. The method for preparing the supramolecular material diverting agent for hydraulic fracturing according to claim 1, characterized in that: The frequency of the ultrasonic treatment in step 2 is 20-40kHz; the ultrasonic time is 2-8h; the centrifugal speed in step 3 is 2000-6000rpm / min; the drying temperature in step 4 is 60-100°C.

6. The method for preparing the supramolecular material diverting agent for hydraulic fracturing according to claim 1, characterized in that: The reagent used for washing in step three is one or more of water, methanol, ethanol, propanol, dimethyl sulfoxide, N,N-dimethylformamide and N-methylpyrrolidone.

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

8. Use of the supramolecular material diverting agent for hydraulic fracturing as claimed in claim 7 in hydraulic fracturing technology in oil and gas fields.

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

10. The use of the supramolecular material diverting agent for hydraulic fracturing according to claim 9 in the hydraulic fracturing technology of oil and gas fields, characterized in 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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