Temporary plugging agent composition for oilfield fracturing as well as preparation method and application of temporary plugging agent composition

Abstract

The invention relates to the field of petroleum engineering and chemical engineering, and discloses a temporary plugging agent composition for oilfield fracturing as well as a preparation method and application of the temporary plugging agent composition. The composition contains polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a thickening agent D and water, the thickening agent D is a water-soluble active polymer, the water-soluble active polymer is a copolymer containing a structural unit as shown in a formula (1) and a structural unit as shown in a formula (2), the content of the structural unit as shown in the formula (1) is 80-95 wt%, the content of the structural unit as shown in the formula (2) is 5-20 wt%, # imgabs0 # n is 6-14, and R1 is C7-C17 alkyl. The composition comprises a water-soluble active polymer and has good flowability; all the components cooperate with one another, so that the crude oil recovery rate is increased; and the composition can be almost completely degraded after a period of time, and pollution to the stratum environment is avoided.

Description

Technical Field

[0001] The present invention belongs to the fields of petroleum engineering and chemical engineering, and particularly relates to a temporary plugging agent composition for oilfield fracturing, a preparation method thereof and an application thereof. Background Art

[0002] As a main measure for reservoir transformation, the hydraulic fracturing technology can enable new wells to be put into production and old wells to maintain stable production, so as to improve the single-well production capacity, and has been widely applied worldwide. However, with the extension of the water injection development time, the crude oil in the oil drainage area formed by the initial hydraulic fracturing operation is continuously produced, and the oil content of the produced fluid continuously decreases, resulting in a gradual decline in the single-well output. However, there are still remaining oil reserves that have not been affected outside the oil drainage area. In view of such a situation, at present, the temporary plugging and diversion refracturing technology is mainly adopted in the oilfield field to improve the single-well production capacity. The key to the temporary plugging and diversion refracturing technology is to create a new fracture, and the most important thing for creating a new fracture is to select a suitable temporary plugging agent. Therefore, the fracturing temporary plugging agent is one of the keys to the temporary plugging and diversion refracturing construction technology. Optimizing a fracturing temporary plugging agent for plugging old fractures and fracturing new fractures in low-permeability oilfields has a positive effect on ensuring the oilfield production capacity and enhancing the oil production effect.

[0003] According to different temporary plugging materials, the temporary plugging agents for oilfield fracturing can be divided into inert inorganic solid temporary plugging agents (such as silica powder, rock salt, plugging balls, calcium carbonate powder, etc.) and inert organic resin temporary plugging agents (such as oil-soluble resins, water-soluble polymer gels, etc.); in addition, according to the plugging removal method of the fracturing temporary plugging agent after 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. However, the above fracturing temporary plugging agents all require subsequent plugging removal to release the original formation fractures, and the plugging removal process is complex, which is prone to a series of problems such as reservoir damage and incomplete plugging removal, seriously restricting the application and promotion of the fracturing temporary plugging technology. Therefore, there is an urgent need to develop a fracturing temporary plugging agent with good injectability in high-temperature reservoirs, which can fracture new oil and gas seepage channels and degrade autonomously, and has important economic value and practical significance for the stable production of old oilfields and the production increase of new wells in China.

[0004] Water-soluble active polymers can improve the oil displacement efficiency by being used as polymers for oil displacement in the field of tertiary oil recovery, but there is no report on their application in the field of oilfield fracturing. Summary of the Invention

[0005] The object of the present invention is to overcome the problems of poor injectability of existing fracturing temporary plugging agents in high-temperature reservoirs, low crude oil recovery rate, and the need for subsequent plug removal. The present invention provides a temporary plugging agent composition for oilfield fracturing, its preparation method and application. The composition includes a water-soluble active polymer. Since the water-soluble active polymer can activate the surface ester groups of polyglycolic acid, when the composition is used for high-temperature oilfield fracturing, it has good fluidity; each component cooperates with each other to emulsify with crude oil, improving the crude oil recovery rate; and the composition can achieve almost complete degradation after a period of time, without causing pollution to the formation environment.

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

[0007] The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%.

[0008]

[0009] n is 6-14, and R1 is an alkyl group with 7-17 carbon atoms.

[0010] The second aspect of the present invention provides a preparation method of a temporary plugging agent composition for oilfield fracturing, characterized by including the following steps:

[0011] (1) Add the thickener D to water and perform the first stirring to obtain a mixed solution I;

[0012] (2) Add the main emulsifier B to the above mixed solution I and perform the second stirring to obtain a mixed emulsion II;

[0013] (3) Add the co-emulsifier C to the above mixed emulsion II and perform the third stirring to obtain a mixed emulsion III;

[0014] (4) Add polyglycolic acid A to the above mixed emulsion III and perform the fourth stirring to obtain the temporary plugging agent composition for oilfield fracturing;

[0015] The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%.

[0016]

[0017] n is from 8 to 12, and R1 is an alkyl group having 9 to 15 carbon atoms.

[0018] The third aspect of the present invention provides a temporary plugging agent composition prepared by the above method.

[0019] The fourth aspect of the present invention provides the application of the above temporary plugging agent composition in fracturing under high-temperature reservoir conditions.

[0020] Through the above technical solutions, the temporary plugging agent composition for oilfield fracturing provided by the present invention, its preparation method and application obtain the following beneficial effects:

[0021] In the present invention, the thickener D in the temporary plugging agent composition is a water-soluble active polymer, which not only plays a role in thickening the system, but also can have a synergistic activation effect with the ester groups in the surface molecular chains of the polyglycolic acid A particles, further activating the particles, embedding, entangling and uniformly dispersing the particles and fixing them in the active polymer network structure, preventing agglomeration and adhesion between the particles, greatly improving the suspension stability of the particles, and enabling the composition to have good injectability.

[0022] Furthermore, the temporary plugging agent composition is almost completely degraded within 72 hours under high-temperature reservoir conditions, and the residue after degradation is less than 5%, without the need for plug removal, and can enter the reservoir together with the subsequent injected water.

[0023] Furthermore, the main emulsifier B and the co-emulsifier C reduce the surface tension between oil and water and can emulsify with the crude oil, thereby improving the oil recovery rate. Detailed embodiments

[0024] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and 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.

[0025] The first aspect of the present invention provides an oilfield fracturing temporary plugging agent composition, characterized in that the composition contains polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a thickener D and water;

[0026] The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%.

[0027]

[0028]

[0029] n is from 6 to 14, and R1 is an alkyl group having 7 to 17 carbon atoms.

[0030] In the present invention, the oilfield fracturing temporary plugging agent composition contains a specific thickener D, which is a water-soluble active polymer with excellent thickening properties. Moreover, it can activate the ester groups in the molecular chains on the surface of the polyglycolic acid A particles, enabling the polyglycolic acid A particles to be uniformly dispersed and fixed in the active polymer network structure, preventing agglomeration and adhesion between the particles, greatly enhancing the suspension stability of the particles, and making the composition have good injectability.

[0031] In the present invention, the water is common oilfield water, formation water, etc. in the art, and the present invention does not make special limitations thereon.

[0032] According to the present invention, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 0.5 - 10 parts by weight, the content of the main emulsifier B is 0.1 - 5 parts by weight, the content of the co-emulsifier C is 0.1 - 2.5 parts by weight, and the content of the thickener D is 0.2 - 2 parts by weight.

[0033] In the present invention, the composition with the above specific content has excellent stability. When used as a temporary plugging agent in a high-temperature oil reservoir, it will not delaminate, has good injectability, and can bear a certain pressure after injection, showing good pressure-bearing performance.

[0034] In the present invention, a high-temperature oil reservoir refers to an oil reservoir with a temperature greater than or equal to 100 °C.

[0035] Further, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 1 - 7 parts by weight, the content of the main emulsifier B is 0.5 - 3 parts by weight, the content of the co-emulsifier C is 0.2 - 1 part by weight, and the content of the thickener D is 0.3 - 1 part by weight.

[0036] According to the present invention, the thickener D is a water-soluble active polymer, and the water-soluble active polymer is a homopolymer having structural units shown in formula (1) and formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80 - 90 wt%, and the content of the structural unit shown in formula (2) is 10 - 20 wt%.

[0037] According to the present invention, n is from 8 to 12, and R1 is an alkyl group having 9 to 15 carbon atoms.

[0038] According to the present invention, the viscosity-average molecular weight of the water-soluble active polymer is 5 million - 25 million, preferably 11 million - 25 million.

[0039] According to the present invention, the polyglycolic acid A is a micron-sized particle.

[0040] According to the present invention, the median particle size D50 of the polyglycolic acid A is 5 - 100 μm.

[0041] In the present invention, the micron-sized polyglycolic acid A is selected, which is suitable for the fracturing operation under high-temperature reservoir conditions, has good injectability, and can bear a relatively high pressure.

[0042] According to the present invention, the median particle size D50 of the polyglycolic acid A is 20 - 80 μm.

[0043] In the present invention, a laser particle size analyzer is used to detect the median particle size D50 of the polyglycolic acid A. The method for preparing the particle size of the polyglycolic acid A is a conventional method in the art, and the polyglycolic acid A can meet the requirements within this particle size range.

[0044] According to the present invention, the number-average molecular weight of the polyglycolic acid A is 50,000 - 150,000, preferably 80,000 - 120,000.

[0045] According to the present invention, the main emulsifier B is an anionic emulsifier.

[0046] Further, the main emulsifier B is selected from at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate.

[0047] According to the present invention, the co-emulsifier C is a non-ionic emulsifier.

[0048] Further, the co-emulsifier C is selected from at least one of Span 20, Span 40, Span 60, Span 80, Tween 20, Tween 40, Tween 60, and Tween 80, preferably at least one of Span 60, Span 80, Tween 40, and Tween 60.

[0049] In the present invention, after being injected into the high-temperature reservoir formation, the main emulsifier B and the co-emulsifier C can continue to emulsify with the crude oil, the fluid does not separate, the suspension stability of the composition is improved, the fluidity after injection is good, and thus the oil recovery rate is increased.

[0050] The second aspect of the present invention provides a preparation method of an oilfield fracturing temporary plugging agent composition, which is characterized by comprising the following steps:

[0051] (1) Adding the thickener D to water and performing the first stirring to obtain the mixed solution I;

[0052] (2) Adding the main emulsifier B to the above-mentioned mixed solution I and performing the second stirring to obtain the mixed emulsion II;

[0053] (3) Adding the co-emulsifier C to the above-mentioned mixed emulsion II and performing the third stirring to obtain the mixed emulsion III;

[0054] (4) Add polyglycolic acid A to the above-mentioned mixed emulsion III, and perform the fourth stirring to obtain the oilfield fracturing temporary plugging agent composition;

[0055] The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%.

[0056]

[0057] n is 6-14, and R1 is an alkyl group with 7-17 carbon atoms.

[0058] In the present invention, adopting the specific feeding sequence described in the present invention will make the prepared composition system more stable.

[0059] The types and dosages 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 understand it as a limitation to the present invention.

[0060] According to the present invention, the first stirring time is 30-120 min, and the temperature is 20-60 °C; more preferably, the first stirring time is 45-90 min, and the temperature is 30-50 °C.

[0061] According to the present invention, 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.

[0062] According to the present invention, the third stirring time is 10-30 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.

[0063] According to the present invention, the fourth stirring time is 5-30 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.

[0064] In the present invention, the specific stirring time and stirring temperature enable the orderly connection of the processes, improve the suspension stability of the composition and the compatibility with the on-site water sample, and meet the requirements of on-site construction.

[0065] According to a particularly preferred embodiment of the present invention, the oilfield fracturing temporary plugging agent composition is prepared according to the following steps:

[0066] Step 1: Weigh 0.3 - 0.45 parts by weight of thickener D, add it to 100 parts by weight of water, and stir well at 30 - 50 °C for 45 - 60 min to obtain mixed solution I;

[0067] Step 2: Weigh 0.5 - 3 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;

[0068] Step 3: Weigh 0.2 - 1 part 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;

[0069] Step 4: Weigh 1 - 5 parts by weight of polyglycolic acid A and add it to the mixed emulsion III obtained in Step 3. Stir well at 30 - 50 °C for 10 - 20 min to obtain the temporary plugging agent composition.

[0070] The third aspect of the present invention provides a temporary plugging agent composition prepared by the above - mentioned preparation method.

[0071] The fourth aspect of the present invention provides a fracturing application of the above - mentioned oilfield fracturing temporary plugging agent composition under high - temperature reservoir conditions.

[0072] The present invention will be described in detail below through examples. In the following examples,

[0073] The performance test of the temporary plugging agent composition adopts the following standards:

[0074] 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 occurs is observed.

[0075] Surface tension: The surface tension of the polymer solution is measured using a DCAT - 21 type surface tension meter from Dataphysics, Germany, and the measurement temperature is 25 °C.

[0076] The test temperature is 100 °C.

[0077] Temporary plugging pressure bearing: Through the fracturing temporary plugging physical model device, the temporary plugging pressure bearing value can be directly read.

[0078] Temporary plugging rate: Through the fracturing temporary plugging physical model device, the permeability value can be directly read. The temporary plugging rate is calculated based on the permeability values before temporary plugging (K1) and after temporary plugging (K2); the calculation formula is: (1 - K2 / K1)×100% is the temporary plugging rate.

[0079] Residue content: Calculated by the mass change before and after degradation at 100°C. The mass before degradation is (M1), and the mass after degradation is (M2). The calculation formula is: (M2 / M1)×100% is the residue content.

[0080] Oil recovery rate: Using artificial cores (length 30 mm, diameter 2.5 mm), after evacuating the cores, saturate them with simulated crude oil. The amount of saturated oil is m1. Then, waterflood until the water cut reaches 98%. Then inject 10 ml of the temporary plugging agent composition. After temporary plugging and fracturing, displace until the water cut reaches 98% again. The oil production is m2. The oil recovery rate = (m2 / m1)×100%.

[0081] Polyglycolic acid A:

[0082] A1: The median particle size D50 is 65 μm, and the number average molecular weight is 120,000.

[0083] A2: The median particle size D50 is 40 μm, and the number average molecular weight is 100,000.

[0084] A3: The median particle size D50 is 80 μm, and the number average molecular weight is 80,000.

[0085] A4: The median particle size D50 is 20 μm, and the number average molecular weight is 80,000.

[0086] A5: The median particle size D50 is 10 μm, and the number average molecular weight is 100,000.

[0087] A6: The median particle size D50 is 100 μm, and the number average molecular weight is 150,000.

[0088] A7: The median particle size D50 is 65 μm, and the number average molecular weight is 50,000.

[0089] Main emulsifier B:

[0090] B1: Sodium dodecyl sulfate, purity > 95%, purchased from Jinan Century Tongda Chemical Co., Ltd.

[0091] B2: Sodium dodecyl sulfonate, purity > 98%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0092] B3: Sodium dodecylbenzenesulfonate, purity > 95%, purchased from Jiangsu Qingting Chemical Co., Ltd.

[0093] Co-emulsifier C:

[0094] C1: Tween 40, purity > 95%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0095] C2: Tween 60, purity > 95%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0096] C3: Span 80, purity > 95%, purchased from Shanghai Hansi Chemical Co., Ltd.;

[0097] C4: Span 60, purity > 95%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0098] Thickener D:

[0099] D1: In the water-soluble active polymer, n is 10, R1 is an alkyl group with 12 carbon atoms, the viscosity-average molecular weight is 21 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 90 wt%, and the content of the structural unit shown in formula (2) is 10 wt%, purchased from China Petroleum & Chemical Corporation;

[0100] D2: In the water-soluble active polymer, n is 8, R1 is an alkyl group with 9 carbon atoms, the viscosity-average molecular weight is 15 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 88 wt%, and the content of the structural unit shown in formula (2) is 12 wt%, purchased from China Petroleum & Chemical Corporation;

[0101] D3: In the water-soluble active polymer, n is 12, R1 is an alkyl group with 12 carbon atoms, the viscosity-average molecular weight is 23 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 90 wt%, and the content of the structural unit shown in formula (2) is 10 wt%, purchased from China Petroleum & Chemical Corporation;

[0102] D4: In the water-soluble active polymer, n is 10, R1 is an alkyl group with 15 carbon atoms, the viscosity-average molecular weight is 25 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 87 wt%, and the content of the structural unit shown in formula (2) is 13 wt%, purchased from China Petroleum & Chemical Corporation;

[0103] D5: In the water-soluble active polymer, n is 12, R1 is an alkyl group with 15 carbon atoms, the viscosity-average molecular weight is 11 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 92 wt%, and the content of the structural unit shown in formula (2) is 8 wt%, purchased from China Petroleum & Chemical Corporation;

[0104] D6: In the water-soluble active polymer, n is 8, R1 is an alkyl group with 12 carbon atoms, the viscosity-average molecular weight is 5 million, based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80 wt%, and the content of the structural unit shown in formula (2) is 20 wt%, purchased from China Petroleum & Chemical Corporation;

[0105] D7: In the water-soluble active polymer, n is 14, R1 is an alkyl group with 8 carbon atoms, the viscosity-average molecular weight is 12 million, based on the total weight of the copolymer, the content of the structural unit shown in the formula (1) is 95 wt%, and the content of the structural unit shown in the formula (2) is 5 wt%. It is purchased from China Petroleum & Chemical Corporation;

[0106] D8: In the water-soluble active polymer, n is 16, R1 is an alkyl group with 17 carbon atoms, the viscosity-average molecular weight is 8 million, based on the total weight of the copolymer, the content of the structural unit shown in the formula (1) is 84 wt%, and the content of the structural unit shown in the formula (2) is 16 wt%. It is purchased from China Petroleum & Chemical Corporation.

[0107] Example 1

[0108] Step 1: Weigh 0.45 parts by weight of thickener D1 and add it to 100 parts by weight of water. Stir well at 30 °C for 60 min to obtain mixed solution I;

[0109] Step 2: Weigh 1.5 parts by weight of main emulsifier B1 and add it to the above-mentioned mixed solution I. Stir well at 30 °C for 25 min to obtain mixed emulsion II;

[0110] Step 3: Weigh 0.8 parts by weight of co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. Stir well at 30 °C for 25 min to obtain mixed emulsion III;

[0111] Step 4: Weigh 5 parts by weight of polyglycolic acid A1 and add it to the above-mentioned mixed emulsion III. Stir well at 30 °C for 20 min to obtain a temporary plugging agent composition.

[0112] Example 2

[0113] Step 1: Weigh 0.3 parts by weight of thickener D2 and add it to 100 parts by weight of water. Stir well at 35 °C for 90 min to obtain mixed solution I;

[0114] Step 2: Weigh 0.5 parts by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. Stir well at 35 °C for 20 min to obtain mixed emulsion II;

[0115] Step 3: Weigh 0.2 parts by weight of co-emulsifier C2 and add it to the above-mentioned mixed emulsion II. Stir well at 35 °C for 20 min to obtain mixed emulsion III;

[0116] Step 4: Weigh 7 parts by weight of polyglycolic acid A2 and add it to the above-mentioned mixed emulsion III. Stir well at 35 °C for 15 min to obtain a temporary plugging agent composition.

[0117] Example 3

[0118] Step 1: Weigh 1 part by weight of thickener D3 and add it to 100 parts by weight of water. At 50 °C, after stirring thoroughly for 80 min, a mixed solution I is obtained.

[0119] Step 2: Weigh 3 parts by weight of main emulsifier B3 and add it to the above-mentioned mixed solution I. At 50 °C, after stirring thoroughly for 15 min, a mixed emulsion II is obtained.

[0120] Step 3: Weigh 1 part by weight of co-emulsifier C3 and add it to the above-mentioned mixed emulsion II. At 50 °C, after stirring thoroughly for 15 min, a mixed emulsion III is obtained.

[0121] Step 4: Weigh 1 part by weight of polyglycolic acid A3 and add it to the above-mentioned mixed emulsion III. At 50 °C, after stirring thoroughly for 15 min, a temporary plugging agent composition is obtained.

[0122] Example 4

[0123] Step 1: Weigh 0.2 part by weight of thickener D4 and add it to 100 parts by weight of water. At 20 °C, after stirring thoroughly for 120 min, a mixed solution I is obtained.

[0124] Step 2: Weigh 0.1 part by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. At 20 °C, after stirring thoroughly for 10 min, a mixed emulsion II is obtained.

[0125] Step 3: Weigh 1.5 parts by weight of co-emulsifier C3 and add it to the above-mentioned mixed emulsion II. At 20 °C, after stirring thoroughly for 20 min, a mixed emulsion III is obtained.

[0126] Step 4: Weigh 0.5 part by weight of polyglycolic acid A4 and add it to the above-mentioned mixed emulsion III. At 20 °C, after stirring thoroughly for 30 min, a temporary plugging agent composition is obtained.

[0127] Example 5

[0128] Step 1: Weigh 1.5 parts by weight of thickener D5 and add it to 100 parts by weight of water. At 25 °C, after stirring thoroughly for 40 min, a mixed solution I is obtained.

[0129] Step 2: Weigh 5 parts by weight of main emulsifier B1 and add it to the above-mentioned mixed solution I. At 25 °C, after stirring thoroughly for 30 min, a mixed emulsion II is obtained.

[0130] Step 3: Weigh 0.1 part by weight of co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. At 25 °C, after stirring thoroughly for 10 min, a mixed emulsion III is obtained.

[0131] Step 4: Weigh 10 parts by weight of polyglycolic acid A5 and add it to the above-mentioned mixed emulsion III. After fully stirring at 25°C for 30 minutes, a temporary plugging agent composition is obtained.

[0132] Example 6

[0133] Step 1: Weigh 2 parts by weight of thickener D6 and add it to 100 parts by weight of water. After fully stirring at 60°C for 30 minutes, a mixed solution I is obtained.

[0134] Step 2: Weigh 3.8 parts by weight of main emulsifier B3 and add it to the above-mentioned mixed solution I. After fully stirring at 60°C for 10 minutes, a mixed emulsion II is obtained.

[0135] Step 3: Weigh 2.5 parts by weight of co-emulsifier C4 and add it to the above-mentioned mixed emulsion II. After fully stirring at 60°C for 15 minutes, a mixed emulsion III is obtained.

[0136] Step 4: Weigh 3 parts by weight of polyglycolic acid A6 and add it to the above-mentioned mixed emulsion III. After fully stirring at 60°C for 5 minutes, a temporary plugging agent composition is obtained.

[0137] Example 7

[0138] Implement in the same way as Example 1. Compared with Example 1, use 0.45 parts by weight of thickener D7 to replace thickener D1.

[0139] Example 8

[0140] Implement in the same way as Example 1. Compared with Example 1, use polyglycolic acid A7 to replace polyglycolic acid A1.

[0141] Comparative Example 1

[0142] Implement in the same way as Example 1. Compared with Example 1, do not add thickener D.

[0143] Comparative Example 2

[0144] Implement in the same way as Example 1. Compared with Example 1, use 0.45 parts by weight of thickener D8 to replace thickener D1.

[0145] Comparative Example 3

[0146] Implement in the same way as Example 1. Compared with Example 1, only add main emulsifier B1 and do not add co-emulsifier C1.

[0147] Comparative Example 4

[0148] It is implemented in the same manner as in Example 1. Compared with Example 1, the feeding order in the preparation method is adjusted, and polyglycolic acid A1, main emulsifier B1, co-emulsifier C1, and thickener D1 are added simultaneously.

[0149] The feeding amounts of the examples and comparative examples are shown in Table 1 in detail.

[0150] Table 1

[0151]

[0152] In a high-temperature reservoir, the suspension stability, surface tension, temporary plugging pressure bearing, temporary plugging rate, residue rate, and crude oil recovery rate of the composition are tested. The test data of the temporary plugging agent composition are shown in Table 2 in detail.

[0153] Table 2

[0154]

[0155]

[0156] It can be seen from Table 1 and Table 2 that compared with Example 1, in Comparative Example 1, the thickener D is not added, and the surface tension of Example 1 is small and the fluidity is good; compared with Example 1, in Comparative Example 2, the solubility of the thickener is poor and the particles cannot smoothly enter the ground, and the pressure-bearing effect, temporary plugging rate, and crude oil recovery rate of Example 1 are all higher than those of Comparative Example 2; compared with Example 1, in Comparative Example 3, the emulsifier component is omitted, the dispersibility is reduced, and finally the flow performance decreases; compared with Example 1, in Comparative Example 4, the feeding order in Example 1 makes the solubility of the composition better, has better suspension stability, and better injectability.

[0157] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution 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. An oilfield fracturing temporary plugging agent composition, characterized in that, The composition contains polyglycolic acid A, main emulsifier B, co-emulsifier C, thickener D and water; The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%, n is 6-14, and R1 is an alkyl group with 7-17 carbon atoms.

2. The oilfield fracturing temporary plugging agent composition according to claim 1, wherein Based on 100 parts by weight of water, the content of polyglycolic acid A is 0.5-10 parts by weight, the content of main emulsifier B is 0.1-5 parts by weight, the content of co-emulsifier C is 0.1-2.5 parts by weight, and the content of thickener D is 0.2-2 parts by weight; Preferably, based on 100 parts by weight of water, the content of polyglycolic acid A is 1-7 parts by weight, the content of main emulsifier B is 0.5-3 parts by weight, the content of co-emulsifier C is 0.2-1 part by weight, and the content of thickener D is 0.3-1 part by weight.

3. The oilfield fracturing temporary plugging agent composition according to claim 1 or 2, wherein, Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-90 wt%, and the content of the structural unit shown in formula (2) is 10-20 wt%; Preferably, n is 8-12, and R1 is an alkyl group with 9-15 carbon atoms; Preferably, the viscosity-average molecular weight of the water-soluble active polymer is 5 million to 25 million, preferably 11 million to 25 million.

4. The oilfield fracturing temporary plugging agent composition according to any one of claims 1-3, wherein, The polyglycolic acid A is in the form of micron-sized particles; Preferably, the median particle size D50 of the polyglycolic acid A is 5-100 μm, preferably 20-80 μm; Preferably, the number-average molecular weight of the polyglycolic acid A is 50,000-150,000, preferably 80,000-120,000.

5. The oilfield fracturing temporary plugging agent composition according to any one of claims 1-4, 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 Span 20, Span 40, Span 60, Span 80, Tween 20, Tween 40, Tween 60 and Tween 80, preferably at least one of Span 60, Span 80, Tween 40 and Tween 60.

6. A preparation method of an oilfield fracturing temporary plugging agent composition, characterized in that, It includes the following steps: (1) Add the thickener D to water and perform the first stirring to obtain the mixed solution I; (2) Add the main emulsifier B to the above mixed solution I and perform the second stirring to obtain the mixed emulsion II; (3) Add the co-emulsifier C to the above mixed emulsion II and perform the third stirring to obtain the mixed emulsion III; (4) Add the polyglycolic acid A to the above mixed emulsion III and perform the fourth stirring to obtain the oilfield fracturing temporary plugging agent composition; The thickener D is a water-soluble active polymer, and the water-soluble active polymer is a copolymer containing the structural unit shown in formula (1) and the structural unit shown in formula (2). Based on the total weight of the copolymer, the content of the structural unit shown in formula (1) is 80-95 wt%, and the content of the structural unit shown in formula (2) is 5-20 wt%, n is from 6 to 14, and R1 is an alkyl group having 7 to 17 carbon atoms.

7. The preparation method according to claim 6, wherein, Relative to 100 parts by weight of water, the content of the polyglycolic acid A is from 0.5 to 10 parts by weight, the content of the main emulsifier B is from 0.1 to 5 parts by weight, the content of the co-emulsifier C is from 0.1 to 2.5 parts by weight, and the content of the thickener D is from 0.2 to 2 parts by weight; Preferably, relative to 100 parts by weight of water, the content of the polyglycolic acid A is from 1 to 7 parts by weight, the content of the main emulsifier B is, the content of the co-emulsifier C is from 0.2 to 1 part by weight, and the content of the thickener D is from 0.3 to 1 part by weight.

8. The preparation method according to claim 6 or 7, wherein The polyglycolic acid A is micron-sized particles; Preferably, the median particle size D50 of the polyglycolic acid A is from 5 to 100 μm, preferably from 20 to 80 μm; Preferably, the number average molecular weight of the polyglycolic acid A is from 50,000 to 150,000, preferably from 80,000 to 120,000.

9. The preparation method according to any one of claims 6-8, 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 span 20, span 40, span 60, span 80, tween 20, tween 40, tween 60, and tween 80, preferably at least one of span 60, span 80, tween 40, and tween 60.

10. The preparation method according to any one of claims 6-9, wherein, Based on the total weight of the copolymer, the content of the structural unit represented by formula (1) is 80 - 90 wt%, and the content of the structural unit represented by formula (2) is 10 - 20 wt%; Preferably, n is from 8 to 12, and R1 is an alkyl group having 9 to 15 carbon atoms; Preferably, the viscosity average molecular weight of the water-soluble active polymer is from 5 million to 25 million, preferably from 11 million to 25 million.

11. The preparation method according to any one of claims 7 to 10, wherein, The first stirring time is from 30 to 120 min, and the temperature is from 20 to 60 °C; preferably, the first stirring time is from 45 to 90 min, and the temperature is from 30 to 50 °C; Preferably, the second stirring time is from 10 to 30 min, and the temperature is from 20 to 60 °C; more preferably, the second stirring time is from 15 to 25 min, and the temperature is from 30 to 50 °C; Preferably, the third stirring time is from 10 to 30 min, and the temperature is from 20 to 60 °C; more preferably, the third stirring time is from 15 to 25 min, and the temperature is from 30 to 50 °C; Preferably, the fourth stirring time is from 5 to 30 min, and the temperature is from 20 to 60 °C; more preferably, the fourth stirring time is from 10 to 20 min, and the temperature is from 30 to 50 °C.

12. An oilfield fracturing temporary plugging agent composition prepared by the preparation method according to claims 7 - 11.

13. The fracturing application of the oilfield fracturing temporary plugging agent composition according to any one of claims 1 - 5 and 12 under high-temperature reservoir conditions.

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