High-strength temporary plugging agent composition for oilfield fracturing as well as preparation method and application of high-strength temporary plugging agent composition

Abstract

The invention relates to the field of petroleum engineering and chemical engineering, and discloses a high-strength temporary plugging agent composition for oilfield fracturing, a preparation method thereof and application of the high-strength temporary plugging agent composition in a low-permeability oilfield. The composition contains polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a bio-based polymer D and water, the particle size of the polyglycolic acid A is 10-80 [mu] m; the weight ratio of the polyglycolic acid A to the bio-based polymer D is (1-8): 1. The composition has good suspension stability, can bear the pressure higher than 40 MPa, achieves the purpose and effect of fracture temporary plugging of old joints and fracture of new joints, can achieve complete and rapid degradation without plug removal, meets the site construction requirements, enables a temporary plugging agent to be suitable for low-permeability oil fields, and improves the single well productivity of the low-permeability oil fields.

Description

Technical Field

[0001] The present invention belongs to the fields of petroleum engineering and chemical engineering. Specifically, it relates to a high-strength temporary plugging agent composition for oilfield fracturing, its preparation method, and its application in low-permeability oilfields. Background Art

[0002] Currently, during the development of oil and gas fields, hydraulic fracturing is an important technical means in the development process of the world's oil and gas fields. However, in the middle and late stages of oilfield development, with the ineffective circulation of injected water, the oil production economy decreases year by year. To further reach a large amount of remaining oil in the un-fractured area, the temporary plugging and diversion fracturing technology is usually adopted. This technology has been widely applied in the reservoir transformation of major oil and gas fields at home and abroad. In recent years, the temporary plugging and diversion fracturing technology has been successively developed at home and abroad to support oilfield enterprises to obtain more long-term and stable production from unexploited fractured reservoir formations, maximizing the oil and gas recovery rate of oil and gas fields. As a key auxiliary agent for the temporary plugging and diversion fracturing technology, the temporary plugging agent is pumped into the reservoir formation, which can temporarily block old fractures, change the original liquid flow direction, so as to open new fractures, increase the complexity of the transformed fractures, and further achieve the purpose of improving the productivity of a single well.

[0003] According to the different raw materials of the temporary plugging material, the temporary plugging agent for oilfield fracturing can be divided into inert inorganic solid temporary plugging agents and inert organic resin temporary plugging agents; according to the different plugging removal methods of the temporary plugging material after fracturing construction, it can be divided into acid-soluble fracturing temporary plugging agents, oil-soluble fracturing temporary plugging agents, and water-soluble fracturing temporary plugging agents. It is not difficult to see that all the above types of fracturing temporary plugging agents require subsequent plugging removal processes to release the original formation gaps, and the plugging removal processes are complex, costly, and prone to a series of problems such as reservoir damage and incomplete plugging removal, thus seriously restricting the application and popularization of the fracturing temporary plugging technology. Therefore, there is an urgent need to develop a high-pressure-bearing temporary plugging agent product that is suitable for low permeability, does not require plugging removal, and can be self-degraded, with a wide application range, avoiding waste of oil and gas resources, and improving the exploitation efficiency of oil and gas resources.

[0004] Polyglycolic acid has been preliminarily applied as a temporary plugging material in the oil and gas field and achieved good results. However, its degradation rate under low-permeability reservoir conditions is still relatively slow, which cannot meet the requirements of on-site construction, seriously affecting oil and gas production and wide application. Summary of the Invention

[0005] The object of the present invention is to overcome the problem in the prior art that the fracturing temporary plugging agent has poor compressive resistance in low-permeability reservoirs and subsequent plug removal is required. Provided is a high-strength temporary plugging agent composition for oilfield fracturing, its preparation method and application. The composition of the present invention has good suspension stability, can bear a pressure higher than 40 MPa, achieves the purpose and effect of fracturing and temporarily plugging old fractures and fracturing new fractures, and can be completely and rapidly degraded without plug removal, meeting the requirements of on-site construction, making the temporary plugging agent applicable to low-permeability oilfields and improving the single-well production capacity of low-permeability oilfields.

[0006] To achieve the above object, in the first aspect of the present invention, a high-strength temporary plugging agent composition for fracturing is provided, which is characterized in that the composition contains polyglycolic acid A, main emulsifier B, co-emulsifier C, biopolymer D and water;

[0007] The median particle size D50 of the polyglycolic acid A is 10 - 80 μm;

[0008] The weight ratio of the polyglycolic acid A to the biopolymer D is 1 - 8:1.

[0009] In the second aspect of the present invention, a preparation method of a high-strength temporary plugging agent composition for fracturing is provided, which is characterized in that the preparation method includes the following steps:

[0010] (1) Add the biopolymer D to water and conduct the first stirring to obtain a mixed solution Ⅰ;

[0011] (2) Add the main emulsifier B to the above mixed solution Ⅰ and conduct the second stirring to obtain a mixed emulsion Ⅱ;

[0012] (3) Add the co-emulsifier C to the above mixed emulsion Ⅱ and conduct the third stirring to obtain a mixed emulsion Ⅲ;

[0013] (4) Add the polyglycolic acid A to the above mixed emulsion Ⅲ and conduct the fourth stirring to obtain the high-strength temporary plugging agent composition for fracturing;

[0014] The median particle size D50 of the polyglycolic acid A is 10 - 80 μm;

[0015] The weight ratio of the polyglycolic acid A to the biopolymer D is 1 - 8:1.

[0016] In the third aspect of the present invention, a high-strength temporary plugging agent composition for fracturing prepared by the above method is provided.

[0017] In the fourth aspect of the present invention, the application of the above high-strength temporary plugging agent composition for fracturing in low-permeability reservoirs is provided.

[0018] Through the above technical solutions, the high-strength temporary plugging agent composition for oilfield fracturing provided by the present invention, its preparation method and application obtain the following beneficial effects:

[0019] In the present invention, by defining polyglycolic acid A and biopolymer D with a specific weight ratio, polyglycolic acid A solubilized and emulsified synergistically by main emulsifier B and co-emulsifier C is uniformly dispersed in the three-dimensional network structure formed by the interweaving of macromolecules of biopolymer D, preventing agglomeration and adhesion between particles, enhancing the suspension stability of the composition, greatly increasing the pressure-bearing strength of the system, which can reach 40 MPa under pressure, and having good biodegradability.

[0020] Furthermore, the high-strength temporary plugging agent composition for oilfield fracturing completely degrades within 72 h under the conditions of low-permeability reservoirs, and the residue after degradation is less than 5%, without the need for plug removal. Subsequently, it can enter the reservoir together with the injected water, improving the crude oil recovery rate. Specific Embodiments

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] The first aspect of the present invention provides a high-strength temporary plugging agent composition for fracturing, characterized in that the composition contains polyglycolic acid A, main emulsifier B, co-emulsifier C, biopolymer D and water;

[0023] The median particle size D50 of the polyglycolic acid A is 10 - 80 μm;

[0024] The weight ratio of the polyglycolic acid A to the biopolymer D is 1 - 8:1.

[0025] In the present invention, polyglycolic acid A within this particle size range can bear a relatively high pressure. When the particle size < 10 μm, serious leakage will occur and the pressure-bearing capacity will decrease. When the particle size > 80 μm, it will be difficult to inject in low-permeability reservoirs, increasing the on-site construction difficulty.

[0026] Furthermore, the low-permeability reservoir is a reservoir with a permeability less than or equal to 200 mD.

[0027] In the present invention, polyglycolic acid A and biopolymer D with a specific weight ratio produce a synergistic effect, enabling polyglycolic acid A to be uniformly and effectively dispersed in the three-dimensional network structure formed by the interweaving of macromolecules of biopolymer D, reducing the free movement space of particles, increasing the viscosity of the system, and preventing agglomeration and adhesion between particles.

[0028] In the present invention, the water is common oilfield water or formation water in the art, and the present invention does not make special limitations thereto.

[0029] In the present invention, a laser particle size analyzer is used to detect the median particle size D50 of polyglycolic acid A, and the method for preparing the particle size of polyglycolic acid A is a conventional method in the art, so that polyglycolic acid A can meet any particle size range within this range.

[0030] According to the present invention, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 1-10 parts by weight, the content of the main emulsifier B is 0.5-2 parts by weight, the content of the co-emulsifier C is 0.2-1.5 parts by weight, and the content of the biobased polymer D is 0.4-1.5 parts by weight.

[0031] In the present invention, by using the composition with the above specific content, in a low-permeability reservoir, the composition has good suspension stability, thereby improving the injectability of the composition. The final composition has a high pressure-bearing strength, and the pressure-bearing strength can reach more than 40 MPa, which is suitable for low-permeability oilfields. When the content of polyglycolic acid A is insufficient, the pressure-boosting effect is not ideal and cannot meet the construction requirements. When the addition of polyglycolic acid A is excessive, it will cause injection difficulties and it is difficult to enter the target fracture layer.

[0032] Further, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 3-8 parts by weight, the content of the main emulsifier B is 1-1.8 parts by weight, the content of the co-emulsifier C is 0.5-1.2 parts by weight, and the content of the biobased polymer D is 0.5-1.2 parts by weight.

[0033] According to the present invention, the weight ratio of the polyglycolic acid A to the biobased polymer D is 3-8:1.

[0034] According to the present invention, the median particle size D50 of the polyglycolic acid A is 10-60 μm.

[0035] According to the present invention, the number-average molecular weight of the polyglycolic acid A is 50,000-120,000, preferably 50,000-100,000.

[0036] According to the present invention, the main emulsifier B is an anionic emulsifier.

[0037] Further, the main emulsifier B is selected from at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate.

[0038] According to the present invention, the co-emulsifier C is a nonionic emulsifier.

[0039] Further, the co-emulsifier C is selected from at least one of alkylphenol polyoxyethylene ether OP-10, alkylphenol polyoxyethylene ether OP-15, alkylphenol polyoxyethylene ether OP-20, and alkylphenol polyoxyethylene ether OP-30.

[0040] According to the present invention, the biopolymer D is selected from at least one of guar gum, welan gum, and xanthan gum.

[0041] The second aspect of the present invention provides a method for preparing a high-strength temporary plugging agent composition for fracturing, characterized in that the preparation method includes the following steps:

[0042] (1) Add the biopolymer D to water and perform the first stirring to obtain a mixed solution I;

[0043] (2) Add the main emulsifier B to the above-mentioned mixed solution I and perform the second stirring to obtain a mixed emulsion II;

[0044] (3) Add the co-emulsifier C to the above-mentioned mixed emulsion II and perform the third stirring to obtain a mixed emulsion III;

[0045] (4) Add the polyglycolic acid A to the above-mentioned mixed emulsion III and perform the fourth stirring to obtain the high-strength temporary plugging agent composition for fracturing;

[0046] The median particle size D50 of the polyglycolic acid A is 10 - 80 μm;

[0047] The weight ratio of the polyglycolic acid A to the biopolymer D is 1 - 8:1.

[0048] In the present invention, a specific feeding sequence can give full play to the advantages of each component, making the composition system more stable, the obtained composition having high strength under a low-permeability reservoir, and being able to be completely degraded subsequently.

[0049] The types and amounts of the raw materials of the oilfield fracturing temporary plugging agent composition prepared in the second aspect of the present invention are exactly the same as those of the raw materials described in the first aspect of the present invention. To avoid repetition, the present invention will not elaborate further in this second aspect, and those skilled in the art should not consider it as a limitation to the present invention.

[0050] According to the present invention, the first stirring time is 60 - 150 min and the temperature is 20 - 60 °C; more preferably, the first stirring time is 90 - 120 min and the temperature is 30 - 50 °C.

[0051] According to the present invention, the second stirring time is 15 - 30 min and the temperature is 20 - 60 °C; more preferably, the second stirring time is 15 - 25 min and the temperature is 30 - 50 °C.

[0052] According to the present invention, the third stirring time is 15 - 30 min, and the temperature is 20 - 60°C; more preferably, the third stirring time is 15 - 25 min, and the temperature is 30 - 50°C.

[0053] According to the present invention, the fourth stirring time is 10 - 30 min, and the temperature is 20 - 60°C; more preferably, the fourth stirring time is 10 - 20 min, and the temperature is 30 - 50°C.

[0054] In the present invention, specific stirring time and stirring temperature enable the orderly connection of processes, improve the suspension stability of the composition and the compatibility with on-site water samples, meeting the requirements of on-site construction.

[0055] According to a particularly preferred embodiment of the present invention, the oilfield fracturing temporary plugging agent composition is prepared according to the following steps:

[0056] Step 1, weigh 0.5 - 0.9 parts by weight of biopolymer D, add it to 100 parts by weight of water, and stir well at 30 - 50°C for 90 - 120 min to obtain mixed solution I;

[0057] Step 2, weigh 1 - 1.5 parts by weight of main emulsifier B and add it to the above-mentioned mixed solution I, stir well at 30 - 50°C for 15 - 25 min to obtain mixed emulsion II;

[0058] Step 3, weigh 0.9 - 1.2 parts by weight of co-emulsifier C and add it to the above-mentioned mixed emulsion II, stir well at 30 - 50°C for 15 - 25 min to obtain mixed emulsion III;

[0059] Step 4, weigh 3 - 7.2 parts by weight of polyglycolic acid A and add it to the mixed emulsion III in Step 3, stir well at 30 - 50°C for 10 - 20 min to obtain the high-strength temporary plugging agent composition for fracturing.

[0060] The third aspect of the present invention provides the high-strength temporary plugging agent composition for fracturing prepared by the above preparation method.

[0061] The fourth aspect of the present invention provides an application of the above high-strength temporary plugging agent composition for fracturing in low-permeability reservoirs.

[0062] The present invention will be described in detail below through examples. The present invention will be described in detail below through examples.

[0063] The performance test of the temporary plugging agent composition adopts the following standards:

[0064] Suspension stability: The temporary plugging agent prepared according to the preparation method of the oil well fracturing temporary plugging agent composition of the present invention is transferred to a test tube and sealed, and the number of days when obvious stratification appears is observed.

[0065] Surface tension: The surface tension of the polymer solution was measured using a DCAT-21 surface tensiometer from Dataphysics, Germany, at a measurement temperature of 25°C.

[0066] The test temperature was 50°C, and the simulated formation permeability was less than or equal to 200 mD.

[0067] Temporary plugging pressure bearing: The value of the temporary plugging pressure bearing can be directly read through the fracturing temporary plugging physical model device.

[0068] Temporary plugging ratio: The permeability value can be directly read through the fracturing temporary plugging physical model device. The temporary plugging ratio is calculated based on the permeability before temporary plugging (K1) and the permeability after temporary plugging (K2); the calculation formula is: (1 - K2 / K1) × 100% is the temporary plugging ratio.

[0069] The residue content was calculated based on the mass change before and after degradation at 50°C. The mass before degradation was (M1), and the mass after degradation was (M2). The calculation formula is: (M2 / M1) × 100% is the residue content.

[0070] Crude oil recovery rate: Artificial cores (length 30 mm, diameter 2.5 mm) were used. After the cores were evacuated, they were saturated with simulated crude oil. The amount of saturated oil was m1. Then, water flooding was carried out until the water cut reached 98%. Then, 10 ml of the temporary plugging agent composition was injected. After temporary plugging fracturing, the displacement was continued until the water cut reached 98%. The amount of produced oil was m 2， Crude oil recovery rate = (m2 / m1) × 100%.

[0071] Polyglycolic acid A

[0072] A1: The median particle size D50 was 53 μm, and the number average molecular weight was 80,000.

[0073] A2: The median particle size D50 was 60 μm, and the number average molecular weight was 60,000.

[0074] A3: The median particle size D50 was 46 μm, and the number average molecular weight was 60,000.

[0075] A4: The median particle size D50 was 34 μm, and the number average molecular weight was 80,000.

[0076] A5: The median particle size D50 was 15 μm, and the number average molecular weight was 100,000.

[0077] A6: The median particle size D50 was 22 μm, and the number average molecular weight was 80,000.

[0078] A7: The median particle size D50 was 73 μm, and the number average molecular weight was 150,000.

[0079] A8: The median particle size D50 was 3.6 μm, and the number average molecular weight was 50,000.

[0080] Main emulsifier B:

[0081] B1: Sodium dodecyl sulfate, with a purity > 95%, purchased from Jinan Century Tongda Chemical Co., Ltd.;

[0082] B2: Sodium dodecylbenzenesulfonate, with a purity > 95%, purchased from Jiangsu Qingting Chemical Co., Ltd.;

[0083] B3: Sodium dodecyl sulfonate, with a purity > 98%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0084] Co - emulsifier C

[0085] C1: Alkylphenol polyoxyethylene ether OP - 20, with a purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.;

[0086] C2: Alkylphenol polyoxyethylene ether OP - 30, with a purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.;

[0087] C3: Alkylphenol polyoxyethylene ether OP - 10, with a purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.

[0088] Bio - based polymer D:

[0089] D1: Xanthan gum, with a purity > 99%, purchased from Zhengzhou Huixi Chemical Products Co., Ltd.;

[0090] D2: Welan gum, with a purity > 99%, purchased from Jiangsu Aofu Biotechnology Co., Ltd.;

[0091] D3: Guar gum, with a purity > 99%, purchased from Hubei Dahao Chemical Co., Ltd.

[0092] Example 1

[0093] Step 1, Weigh 0.9 parts by weight of bio - based polymer D1 and add it to 100 parts by weight of water. After stirring well at 50 °C for 90 min, a mixed solution Ⅰ is obtained;

[0094] Step 2, Weigh 1.5 parts by weight of main emulsifier B1 and add it to the above - mentioned mixed solution Ⅰ. After stirring well at 50 °C for 25 min, a mixed emulsion Ⅱ is obtained;

[0095] Step 3, Weigh 0.9 parts by weight of co - emulsifier C1 and add it to the above - mentioned mixed emulsion Ⅱ. After stirring well at 50 °C for 20 min, a mixed emulsion Ⅲ is obtained;

[0096] Step 4, Weigh 7.2 parts by weight of polyglycolic acid A1 and add it to the above - mentioned mixed emulsion Ⅲ. After stirring well at 50 °C for 15 min, the high - strength temporary plugging agent composition for fracturing is obtained.

[0097] Example 2

[0098] Step 1: Weigh 0.6 parts by weight of biobased polymer D2 and add it to 100 parts by weight of water. After stirring well at 44 °C for 115 min, a mixed solution I is obtained;

[0099] Step 2: Weigh 1 part by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. After stirring well at 44 °C for 20 min, a mixed emulsion II is obtained;

[0100] Step 3: Weigh 1.1 parts by weight of co-emulsifier C2 and add it to the above-mentioned mixed emulsion II. After stirring well at 44 °C for 15 min, a mixed emulsion III is obtained;

[0101] Step 4: Weigh 3 parts by weight of polyglycolic acid A2 and add it to the above-mentioned mixed emulsion III. After stirring well at 44 °C for 12 min, the high-strength temporary plugging agent composition for fracturing is obtained.

[0102] Example 3

[0103] Step 1: Weigh 1.5 parts by weight of biobased polymer D3 and add it to 100 parts by weight of water. After stirring well at 60 °C for 60 min, a mixed solution I is obtained;

[0104] Step 2: Weigh 0.8 parts by weight of main emulsifier B3 and add it to the above-mentioned mixed solution I. After stirring well at 60 °C for 23 min, a mixed emulsion II is obtained;

[0105] Step 3: Weigh 1.5 parts by weight of co-emulsifier C3 and add it to the above-mentioned mixed emulsion II. After stirring well at 60 °C for 18 min, a mixed emulsion III is obtained;

[0106] Step 4: Weigh 10 parts by weight of polyglycolic acid A3 and add it to the above-mentioned mixed emulsion III. After stirring well at 60 °C for 30 min, the high-strength temporary plugging agent composition for fracturing is obtained.

[0107] Example 4

[0108] Step 1: Weigh 1.1 parts by weight of biobased polymer D3 and add it to 100 parts by weight of water. After stirring well at 38 °C for 120 min, a mixed solution I is obtained;

[0109] Step 2: Weigh 1.7 parts by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. After stirring well at 38 °C for 25 min, a mixed emulsion II is obtained;

[0110] Step 3: Weigh 0.6 parts by weight of co-emulsifier C2 and add it to the above-mentioned mixed emulsion II. After stirring well at 38 °C for 17 min, a mixed emulsion III is obtained;

[0111] Step 4: Weigh 4.4 parts by weight of polyglycolic acid A4 and add it to the above-mentioned mixed emulsion III. After fully stirring at 38°C for 20 min, the high-strength temporary plugging agent composition for fracturing is obtained.

[0112] Example 5

[0113] Step 1: Weigh 0.4 part by weight of bio-based polymer D3 and add it to 100 parts by weight of water. After fully stirring at 20°C for 130 min, the mixed solution I is obtained.

[0114] Step 2: Weigh 0.5 part by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. After fully stirring at 20°C for 20 min, the mixed emulsion II is obtained.

[0115] Step 3: Weigh 1.4 parts by weight of co-emulsifier C3 and add it to the above-mentioned mixed emulsion II. After fully stirring at 20°C for 20 min, the mixed emulsion III is obtained.

[0116] Step 4: Weigh 1 part by weight of polyglycolic acid A5 and add it to the above-mentioned mixed emulsion III. After fully stirring at 20°C for 10 min, the high-strength temporary plugging agent composition for fracturing is obtained.

[0117] Example 6

[0118] Step 1: Weigh 1.3 parts by weight of bio-based polymer D1 and add it to 100 parts by weight of water. After fully stirring at 25°C for 150 min, the mixed solution I is obtained.

[0119] Step 2: Weigh 2 parts by weight of main emulsifier B1 and add it to the above-mentioned mixed solution I. After fully stirring at 25°C for 28 min, the mixed emulsion II is obtained.

[0120] Step 3: Weigh 0.2 part by weight of co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. After fully stirring at 25°C for 20 min, the mixed emulsion III is obtained.

[0121] Step 4: Weigh 1.3 parts by weight of polyglycolic acid A6 and add it to the above-mentioned mixed emulsion III. After fully stirring at 25°C for 28 min, the high-strength temporary plugging agent composition for fracturing is obtained.

[0122] Example 7

[0123] Implement according to the method of Example 1, using polyglycolic acid A7 to replace polyglycolic acid A1.

[0124] Comparative Example 1

[0125] It was implemented in the same manner as in Example 1. Compared with Example 1, the addition amount of the biobased polymer D1 was adjusted to 0.275 parts by weight.

[0126] Comparative Example 2

[0127] It was implemented in the same manner as in Example 1. Compared with Example 1, polyglycolic acid A8 was used to replace polyglycolic acid A1.

[0128] Comparative Example 3

[0129] Compared with Example 1, the feeding order in the preparation method was adjusted, and polyglycolic acid A1, main emulsifier B1, co-emulsifier C1 and biobased polymer D1 were added simultaneously.

[0130] For the specific dosage of each component, see Table 1 for details.

[0131] Table 1

[0132]

[0133]

[0134] In a low-permeability oilfield at 50 °C, the suspension stability, surface tension, temporary plugging pressure bearing, temporary plugging rate, residue rate and crude oil recovery rate of the composition were tested. For the test data of the temporary plugging agent composition, see Table 2 for details.

[0135] Table 2

[0136]

[0137] It can be seen from Table 1 and Table 2 that compared with Example 1 in Comparative Example 1, the weight ratio of polyglycolic acid A to thickener D changed. The temporary plugging agent composition in Example 1 had good injectability, penetrated deep into the reservoir, and its pressure-bearing capacity was enhanced; compared with Example 1 in Comparative Example 2, the particle size of polyglycolic acid A became smaller, resulting in serious leakage. The one in Example 1 could bear higher pressure, had a higher temporary plugging rate and a higher crude oil recovery rate; compared with Example 1 in Comparative Example 3, the feeding order during preparation changed. The composition in Example 1 had high solubility and good suspension stability, thus enhancing the pressure-bearing capacity.

[0138] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A high-strength temporary plugging agent composition for fracturing, characterized in that, The composition contains polyglycolic acid A, main emulsifier B, co-emulsifier C, biobased polymer D and water; The median particle size D50 of the polyglycolic acid A is 10 - 80 μm; The weight ratio of the polyglycolic acid A to the biobased polymer D is 1 - 8:

1.

2. The composition according to claim 1, wherein, Relative to 100 parts by weight of water, the content of the polyglycolic acid A is 1 - 10 parts by weight, the content of the main emulsifier B is 0.5 - 2 parts by weight, the content of the co-emulsifier C is 0.2 - 1.5 parts by weight, and the content of the biobased polymer D is 0.4 - 1.5 parts by weight; Preferably, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 3 - 8 parts by weight, the content of the main emulsifier B is 1 - 1.8 parts by weight, the content of the co-emulsifier C is 0.5 - 1.2 parts by weight, and the content of the biobased polymer D is 0.5 - 1.2 parts by weight.

3. The composition according to claim 1 or 2, wherein, The weight ratio of the polyglycolic acid A to the biobased polymer D is 3 - 8:1; Preferably, the median particle size D50 of the polyglycolic acid A is 10 - 60 μm; Preferably, the number-average molecular weight of the polyglycolic acid A is 50,000 - 120,000, preferably 50,000 - 100,000.

4. The composition according to any one of claims 1-3, wherein, The main emulsifier B is an anionic emulsifier; Preferably, the main emulsifier B is selected from at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; Preferably, the co-emulsifier C is a nonionic emulsifier; Preferably, the co-emulsifier C is selected from at least one of alkylphenol polyoxyethylene ether OP-10, alkylphenol polyoxyethylene ether OP-15, alkylphenol polyoxyethylene ether OP-20 and alkylphenol polyoxyethylene ether OP-30; Preferably, the biobased polymer D is selected from at least one of guar gum, welan gum and xanthan gum.

5. A preparation method of a high-strength temporary plugging agent composition for fracturing, characterized in that, The preparation method comprises the following steps: (1) Add the biobased polymer D to water and perform the first stirring to obtain a mixed solution I; (2) Add the main emulsifier B to the above-mentioned mixed solution I and perform the second stirring to obtain a mixed emulsion II; (3) Add the co-emulsifier C to the above-mentioned mixed emulsion II and perform the third stirring to obtain a mixed emulsion III; (4) Add the polyglycolic acid A to the above-mentioned mixed emulsion III and perform the fourth stirring to obtain the high-strength temporary plugging agent composition for fracturing; The median particle size D50 of the polyglycolic acid A is 10 - 80 μm; The weight ratio of the polyglycolic acid A to the biobased polymer D is 1 - 8:

1.

6. The preparation method according to claim 5, wherein, Relative to 100 parts by weight of water, the content of the polyglycolic acid A is 1 - 10 parts by weight, the content of the main emulsifier B is 0.5 - 2 parts by weight, the content of the co-emulsifier C is 0.2 - 1.5 parts by weight, and the content of the biobased polymer D is 0.4 - 1.5 parts by weight; Preferably, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 3 - 8 parts by weight, the content of the main emulsifier B is 1 - 1.8 parts by weight, the content of the co-emulsifier C is 0.5 - 1.2 parts by weight, and the content of the biobased polymer D is 0.5 - 1.2 parts by weight.

7. The preparation method according to claim 5 or 6, wherein The weight ratio of the polyglycolic acid A to the biobased polymer D is 3 - 8:1; Preferably, the median particle size D50 of the polyglycolic acid A is 10 - 60 μm; Preferably, the number-average molecular weight of the polyglycolic acid A is 50,000 - 120,000, preferably 50,000 - 100,000.

8. The preparation method according to any one of claims 5-7, wherein The main emulsifier B is an anionic emulsifier; Preferably, the main emulsifier B is selected from at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate; Preferably, the co-emulsifier C is a non-ionic emulsifier; Preferably, the co-emulsifier C is selected from at least one of alkylphenol polyoxyethylene ether OP-10, alkylphenol polyoxyethylene ether OP-15, alkylphenol polyoxyethylene ether OP-20, and alkylphenol polyoxyethylene ether OP-30; Preferably, the bio-based polymer D is selected from at least one of guar gum, welan gum, and xanthan gum.

9. The preparation method according to any one of claims 5-8, wherein, The first stirring time is 60 - 150 min, and the temperature is 20 - 60 °C; more preferably, the first stirring time is 90 - 120 min, and the temperature is 30 - 50 °C; Preferably, the second stirring time is 10 - 30 min, and the temperature is 20 - 60 °C; more preferably, the second stirring time is 15 - 25 min, and the temperature is 30 - 50 °C; Preferably, the third stirring time is 15 - 30 min, and the temperature is 20 - 60 °C; more preferably, the third stirring time is 15 - 25 min, and the temperature is 30 - 50 °C; Preferably, the fourth stirring time is 15 - 30 min, and the temperature is 20 - 60 °C; more preferably, the fourth stirring time is 10 - 20 min, and the temperature is 30 - 50 °C.

10. A high-strength temporary plugging agent composition for fracturing prepared by the preparation method according to claims 5 - 9.

11. Application of the high-strength temporary plugging agent composition for fracturing according to any one of claims 1 - 4 and 10 in a low-permeability reservoir.

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