Oil well fracturing temporary plugging agent composition as well as preparation method and application thereof

Abstract

The invention relates to the field of petroleum engineering and chemical engineering, and discloses a temporary plugging agent composition for oilfield fracturing, a preparation method thereof and application of the temporary plugging agent composition in a high-temperature oil well. The composition contains polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a micro-crosslinked polymer D and water, the micro-crosslinked polymer is an acrylamide polymer; the crosslinking degree of the micro-crosslinked polymer D is 2-8%; 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 0.1-2 parts by weight, the content of the co-emulsifier C is 0.05-1 part by weight, and the content of the micro-crosslinked polymer D is 0.3-1 part by weight. The composition has relatively strong anti-pressure ability, can effectively block original gaps after entering a high-temperature stratum, presents rigidity in a short time, can bear pressure of 35 MPa, realizes the effects of temporarily blocking old gaps by fracturing and simultaneously fracturing new gaps, and meanwhile, the composition realizes unblocking in a period of time and does not pollute the stratum.

Description

Technical Field

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

[0002] At present, during the development of oil and gas fields, hydraulic fracturing is an effective technical means for developing conventional and unconventional oil and gas resources. The more complex the fracture network of the reservoir, the greater the stimulation of the reservoir drainage area, and thus the higher the recovery rate. This technology has developed rapidly in the field of newly drilled wells. However, in the later stage of oil well 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 refracturing technology is usually adopted, that is, the temporary plugging agent is injected into the oil reservoir formation through a pump. The temporary plugging agent will preferentially enter the original formation cracks and form a temporary plug. Subsequently, when the subsequent fracturing fluid is further injected, new formation cracks can be generated by fracturing. During the subsequent continuous water injection development process, the water drive fluid can enter the oil-rich area that has not been affected, thereby achieving the purpose of improving the productivity of a single well. This technology has been widely applied worldwide.

[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 plug 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 plug removal processes to release the original formation cracks, and the plug removal processes are complex, costly, and prone to a series of problems such as reservoir damage and incomplete plug removal, which seriously restricts the application and popularization of the fracturing temporary plugging technology. Therefore, there is an urgent need to develop a high-pressure-bearing fracturing temporary plugging agent product that does not require plug removal and can be self-degraded, so as to effectively plug the high-temperature reservoir, and at the same time achieve new crack fracturing in old oilfields, which can achieve the effect of increasing production and stabilizing production and improve the crude oil recovery rate.

[0004] Acrylamide polymers are used as polymers for enhanced oil recovery in the field of tertiary oil recovery. They can penetrate deep into the reservoir under a certain pressure and have strong fluidity in the formation, but their plugging strength is relatively low and does not meet the fracturing requirements. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art that the fracturing temporary plugging agent has poor compressive resistance in high-temperature reservoirs and requires subsequent plug removal. The present invention provides a temporary plugging agent composition for oil well fracturing, its preparation method and application. The composition has strong compressive ability, can effectively plug the original cracks after entering the high-temperature formation, shows rigidity in a short time, can withstand a pressure of up to 35 MPa, realizes the effect of fracturing and temporarily plugging old cracks and fracturing new cracks at the same time, and at the same time the composition is unplugged within a certain period of time without polluting the formation.

[0006] To achieve the above object, a first aspect of the present invention provides an oil well fracturing temporary plugging agent composition, characterized in that the composition comprises polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a micro-crosslinked polymer D and water;

[0007] The micro-crosslinked polymer D is an acrylamide polymer;

[0008] The crosslinking degree of the micro-crosslinked polymer D is 2-8%;

[0009] Relative to 100 parts by weight of water, the content of polyglycolic acid A is 0.5-10 parts by weight, the content of the main emulsifier B is 0.1-2 parts by weight, the content of the co-emulsifier C is 0.05-1 part by weight, and the content of the micro-crosslinked polymer D is 0.3-1 part by weight.

[0010] A second aspect of the present invention provides a preparation method of an oil well fracturing temporary plugging agent composition, characterized in that the preparation method comprises the following steps:

[0011] (1) Add the micro-crosslinked polymer 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 oil well fracturing temporary plugging agent composition;

[0015] The micro-crosslinked polymer D is an acrylamide polymer;

[0016] The crosslinking degree of the micro-crosslinked polymer D is 2-8%;

[0017] Relative to 100 parts by weight of water, the content of polyglycolic acid A is 0.5-10 parts by weight, the content of the main emulsifier B is 0.1-2 parts by weight, the content of the co-emulsifier C is 0.05-1 part by weight, and the content of the micro-crosslinked polymer D is 0.3-1 part by weight;

[0018] The first stirring time is 30-150 min and the temperature is 20-60 °C.

[0019] A third aspect of the present invention provides an oil well fracturing temporary plugging agent composition prepared by the above method.

[0020] A fourth aspect of the present invention provides an application of the above oil well fracturing temporary plugging agent composition in high-temperature oil well fracturing.

[0021] Through the above technical solutions, the temporary plugging agent composition for oil well fracturing provided by the present invention, its preparation method and application obtain the following beneficial effects:

[0022] In the present invention, the micro-crosslinked polymer D is micro-crosslinked polyacrylamide. Because the micro-crosslinked polymer D has a dense spatial network structure, it can effectively encapsulate the polyglycolic acid A solubilized and emulsified synergistically by the main emulsifier and the co-emulsifier, making the polyglycolic acid A evenly dispersed and fixed in the network structure of the micro-crosslinked polymer D, preventing the aggregation and adhesion between polyglycolic acid particles, and greatly improving the compressive strength of the particles at high temperature, and the compressive strength can reach 35 MPa.

[0023] Furthermore, the temporary plugging agent composition is completely degraded within 72 h under the conditions of high-temperature oil reservoirs. The residue after degradation is less than 5%, and there is no need for plug removal. It can enter the oil reservoir together with the subsequent injected water, reduce the surface tension of oil and water, and can emulsify with crude oil to improve the crude oil recovery rate. Detailed implementation mode

[0024] 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, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values 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 a temporary plugging agent composition for oil well fracturing, characterized in that the composition comprises polyglycolic acid A, a main emulsifier B, a co-emulsifier C, a micro-crosslinked polymer D and water;

[0026] The micro-crosslinked polymer D is an acrylamide polymer;

[0027] The crosslinking degree of the micro-crosslinked polymer D is 2-8%;

[0028] 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 0.1-2 parts by weight, the content of the co-emulsifier C is 0.05-1 part by weight, and the content of the micro-crosslinked polymer D is 0.3-1 part by weight.

[0029] In the present invention, the temporary plugging agent composition for oil well fracturing contains a specific micro-crosslinked polymer D. This micro-crosslinked polymer D is an acrylamide polymer, has a dense spatial network structure, has excellent thickening properties, can encapsulate polyglycolic acid A particles in the network, prevent the aggregation and adhesion between polyglycolic acid A particles, and greatly improve the compressive strength of the particles at high temperature.

[0030] In the present invention, the water is common oilfield water or formation water in the art, and the present invention does not make any special limitation thereto.

[0031] In the present invention, a high-temperature oil well is an oil well with a temperature greater than or equal to 100 °C.

[0032] In the present invention, the composition with the above specific content has good stability. In a high-temperature oil reservoir, it is used as a temporary plugging agent and has strong compressive capacity after being injected into the formation. When the main emulsifier B and the co-emulsifier C are insufficient, the composition will show stratification.

[0033] In the present invention, when the crosslinking degree of the micro-crosslinked polymer D is 2-8%, the micro-crosslinked polymer presents a spatial network structure, which can improve the fluid strength, enhance the coating of the polyglycolic acid particles, and further improve the pressure-bearing performance. When the crosslinking degree is too low, the particles cannot be coated, resulting in poor injectability. When the crosslinking degree is too high, it will affect its own water solubility and the dispersibility with the particles.

[0034] According to the present invention, relative to 100 parts by weight of water, the content of the polyglycolic acid A is 1-5 parts by weight, the content of the main emulsifier B is 0.5-1.5 parts by weight, the content of the co-emulsifier C is 0.2-0.8 parts by weight, and the content of the micro-crosslinked polymer D is 0.5-0.8 parts by weight.

[0035] According to the present invention, the polyglycolic acid A is micron-sized particles.

[0036] According to the present invention, the median particle size D50 of the polyglycolic acid A is 5-100 μm.

[0037] In the present invention, a laser particle size analyzer is used to detect the size of the median particle size D50 of the polyglycolic acid A, and 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 this particle size range.

[0038] In the present invention, the polyglycolic acid A within this particle size range is suitable for high-pressure fracturing operations under high-temperature oil reservoir conditions, can bear a relatively high pressure, and has good suspension stability.

[0039] Further, the median particle size D50 of the polyglycolic acid A is 20-80 μm.

[0040] According to the present invention, the number-average molecular weight of the polyglycolic acid A is 50,000-150,000, preferably 80,000-130,000.

[0041] According to the present invention, the main emulsifier B is an anionic emulsifier.

[0042] According to the present invention, the main emulsifier B is selected from at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate.

[0043] According to the present invention, the co-emulsifier C is a non-ionic emulsifier.

[0044] According to the present invention, 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.

[0045] In the present invention, after being injected into the reservoir formation, the main emulsifier B and the co-emulsifier C can continue to emulsify with the crude oil, having good suspension stability and good fluidity after injection of the composition, thereby improving the crude oil recovery rate.

[0046] According to the present invention, the crosslinking degree of the micro-crosslinked polymer D is 3-6%.

[0047] The second aspect of the present invention provides a preparation method of a well fracturing temporary plugging agent composition, characterized in that the preparation method comprises the following steps:

[0048] (1) Add the micro-crosslinked polymer D to water and conduct the first stirring to obtain a mixed solution I;

[0049] (2) Add the main emulsifier B to the above mixed solution I and conduct the second stirring to obtain a mixed emulsion II;

[0050] (3) Add the co-emulsifier C to the above mixed emulsion II and conduct the third stirring to obtain a mixed emulsion III;

[0051] (4) Add the polyglycolic acid A to the above mixed emulsion III and conduct the fourth stirring to obtain the well fracturing temporary plugging agent composition;

[0052] The micro-crosslinked polymer D is an acrylamide polymer;

[0053] The crosslinking degree of the micro-crosslinked polymer D is 2-8%;

[0054] 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 0.1-2 parts by weight, the content of the co-emulsifier C is 0.05-1 part by weight, and the content of the micro-crosslinked polymer D is 0.3-1 part by weight;

[0055] The first stirring time is 30-150 min, and the temperature is 20-60 °C.

[0056] In the present invention, the composition with a specific content prepared by a specific feeding sequence, stirring time and temperature can be more stable. At a certain temperature, the composition shows rigidity in a short time. When the crosslinking degree of the micro-crosslinked polymer D is 2-8%, the micro-crosslinked polymer has a spatial network structure, which can improve the fluid strength, enhance the coating of the polyglycolic acid particles, and has a strong compressive capacity in high-temperature reservoirs.

[0057] 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.

[0058] According to the present invention, the first stirring time is 60-120 min and the temperature is 30-50 °C.

[0059] According to the present invention, the second stirring time is 10-40 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.

[0060] According to the present invention, the third stirring time is 10-40 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.

[0061] 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.

[0062] In the present invention, the specific stirring time and temperature enable the orderly connection of the processes, improve the suspension stability of the composition and the compatibility with the on-site water sample, meeting the requirements of on-site construction.

[0063] According to a particularly preferred embodiment of the present invention, the oilfield fracturing temporary plugging agent composition is prepared according to the following steps:

[0064] Step 1: Weigh 0.5-0.76 parts by weight of the micro-crosslinked polymer D, add it to 100 parts by weight of water, and stir well at 34-50 °C for 60-120 min to obtain a mixed solution I;

[0065] Step 2: Weigh 0.5-1.3 parts by weight of the main emulsifier B and add it to the above mixed solution I, and stir well at 30-50 °C for 15-25 min to obtain a mixed emulsion II;

[0066] Step 3: Weigh 0.2 - 0.67 parts by weight of co - emulsifier C and add it to the above - mentioned mixed emulsion II. After fully stirring at 30 - 50 °C for 15 - 25 min, a mixed emulsion III is obtained;

[0067] Step 4: Weigh 1 - 4.8 parts by weight of polyglycolic acid A and add it to the mixed emulsion III obtained in Step 3. After fully stirring at 30 - 50 °C for 13 - 20 min, a temporary plugging agent composition is obtained.

[0068] The third aspect of the present invention provides an oil - well fracturing temporary plugging agent composition prepared by the above method.

[0069] The fourth aspect of the present invention provides an application of the above - mentioned oil - well fracturing temporary plugging agent composition in high - temperature oil - well fracturing.

[0070] The present invention will be described in detail below through examples.

[0071] The performance test of the temporary plugging agent composition adopts the following standards:

[0072] 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.

[0073] Surface tension: The surface tension of the polymer solution is measured by using a DCAT - 21 type surface tension meter produced by Dataphysics Company, Germany, and the measurement temperature is 25 °C.

[0074] The test temperature is 100 °C.

[0075] Temporary plugging pressure bearing: Through the fracturing temporary plugging physical model device, the temporary plugging pressure - bearing value can be directly read.

[0076] Temporary plugging rate: Through the fracturing temporary plugging physical model device, the permeability value can be directly read. The temporary plugging rate is calculated through 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.

[0077] Residue content: It is 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.

[0078] Crude oil recovery rate: Artificial cores (length 30 mm, diameter 2.5 mm) are used. After the cores are evacuated, they are saturated with simulated crude oil. The amount of saturated oil is m1. Then, water flooding is carried out until the water cut reaches 98%. Then, 10 ml of the temporary plugging agent composition is injected. After temporary plugging and fracturing, the displacement is continued until the water cut reaches 98%. The oil production is m2. The crude oil recovery rate = (m2 / m1)×100%.

[0079] Polyglycolic acid A:

[0080] A1: The median particle size D50 is 62 μm and the number average molecular weight is 130,000;

[0081] A2: The median particle size D50 is 48 μm and the number average molecular weight is 120,000;

[0082] A3: The median particle size D50 is 35 μm and the number average molecular weight is 80,000;

[0083] A4: The median particle size D50 is 22 μm and the number average molecular weight is 100,000;

[0084] A5: The median particle size D50 is 78 μm and the number average molecular weight is 120,000;

[0085] A6: The median particle size D50 is 62 μm and the number average molecular weight is 50,000.

[0086] Main emulsifier B:

[0087] B1: Sodium dodecylbenzenesulfonate, purity > 95%, purchased from Jiangsu Qingting Chemical Co., Ltd.;

[0088] B2: Sodium dodecyl sulfate, purity > 95%, purchased from Jinan Century Tongda Chemical Co., Ltd.;

[0089] B3: Sodium dodecyl sulfonate, purity > 98%, purchased from Shanghai Hansi Chemical Co., Ltd.

[0090] Co-emulsifier C:

[0091] C1: OP-10, purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.;

[0092] C2: OP-30, purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.;

[0093] C3: OP-20, purity > 95%, purchased from Shanghai Bofeimeike Chemical Technology Co., Ltd.

[0094] Micro-crosslinked polymer D:

[0095] D1: Polyacrylamide with a crosslinking degree of 8%, purchased from Dongying Baomo Biochemical Co., Ltd.;

[0096] D2: Polyacrylamide with a crosslinking degree of 6%, purchased from Dongying Baomo Biochemical Co., Ltd.;

[0097] D3: Polyacrylamide with a crosslinking degree of 4%, purchased from Dongying Baomo Biochemical Co., Ltd.;

[0098] D4: Polyacrylamide with a crosslinking degree of 2%, purchased from Dongying Baomo Biochemical Co., Ltd.;

[0099] D5: Polyacrylamide with a crosslinking degree of 10%, purchased from Dongying Baomo Biochemical Co., Ltd.;

[0100] D6: Polyacrylic acid with a crosslinking degree of 6%, purchased from Shandong Nuoer Biotechnology Co., Ltd.;

[0101] D7: Uncrosslinked polyacrylamide, purchased from Shandong Nuoer Biotechnology Co., Ltd.

[0102] Example 1

[0103] Step 1: Weigh 0.76 parts by weight of the micro-crosslinked polymer D1 and add it to 100 parts by weight of water. After fully stirring at 35 °C for 100 min, a mixed solution I is obtained;

[0104] Step 2: Weigh 1.3 parts by weight of the main emulsifier B1 and add it to the above-mentioned mixed solution I. After fully stirring at 35 °C for 15 min, a mixed emulsion II is obtained;

[0105] Step 3: Weigh 0.67 parts by weight of the co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. After fully stirring at 35 °C for 18 min, a mixed emulsion III is obtained;

[0106] Step 4: Weigh 4.8 parts by weight of polyglycolic acid A1 and add it to the above-mentioned mixed emulsion III. After fully stirring at 35 °C for 13 min, the oil well fracturing temporary plugging agent composition is obtained.

[0107] Example 2

[0108] Step 1: Weigh 0.5 parts by weight of the micro-crosslinked polymer D2 and add it to 100 parts by weight of water. After fully stirring at 30 °C for 120 min, a mixed solution I is obtained;

[0109] Step 2: Weigh 0.6 parts by weight of the main emulsifier B2 and add it to the above-mentioned mixed solution I. After fully stirring at 30 °C for 20 min, a mixed emulsion II is obtained;

[0110] Step 3: Weigh 0.2 parts by weight of the co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. After fully stirring at 30 °C for 15 min, a mixed emulsion III is obtained;

[0111] Step 4: Weigh 1.5 parts by weight of polyglycolic acid A2 and add it to the above-mentioned mixed emulsion III. After fully stirring at 30 °C for 15 min, the oil well fracturing temporary plugging agent composition is obtained.

[0112] Example 3

[0113] Step 1: Weigh 0.65 parts by weight of the micro-crosslinked polymer D3 and add it to 100 parts by weight of water. After fully stirring at 50 °C for 95 min, a mixed solution I is obtained;

[0114] Step 2: Weigh 1 part by weight of main emulsifier B3 and add it to the above-mentioned mixed solution I. After fully stirring at 50 °C for 20 min, a mixed emulsion II is obtained;

[0115] Step 3: Weigh 0.8 part by weight of co-emulsifier C2 and add it to the above-mentioned mixed emulsion II. After fully stirring at 50 °C for 22 min, a mixed emulsion III is obtained;

[0116] Step 4: Weigh 3.2 parts by weight of polyglycolic acid A3 and add it to the above-mentioned mixed emulsion III. After fully stirring at 50 °C for 12 min, the oil well fracturing temporary plugging agent composition is obtained.

[0117] Example 4

[0118] Step 1: Weigh 0.3 part by weight of micro-crosslinked polymer D4 and add it to 100 parts by weight of water. After fully stirring at 20 °C for 60 min, a mixed solution I is obtained;

[0119] Step 2: Weigh 0.1 part by weight of main emulsifier B1 and add it to the above-mentioned mixed solution I. After fully stirring at 20 °C for 25 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. After fully stirring at 20 °C for 15 min, a mixed emulsion III is obtained;

[0121] Step 4: Weigh 0.5 part by weight of polyglycolic acid A4 and add it to the above-mentioned mixed emulsion III. After fully stirring at 20 °C for 10 min, the oil well fracturing temporary plugging agent composition is obtained.

[0122] Example 5

[0123] Step 1: Weigh 1 part by weight of micro-crosslinked polymer D1 and add it to 100 parts by weight of water. After fully stirring at 60 °C for 150 min, a mixed solution I is obtained;

[0124] Step 2: Weigh 2 parts by weight of main emulsifier B2 and add it to the above-mentioned mixed solution I. After fully stirring at 60 °C for 20 min, a mixed emulsion II is obtained;

[0125] Step 3: Weigh 0.05 part by weight of co-emulsifier C1 and add it to the above-mentioned mixed emulsion II. After fully stirring at 60 °C for 17 min, a mixed emulsion III is obtained;

[0126] 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 60 °C for 30 min, the oil well fracturing temporary plugging agent composition is obtained.

[0127] Example 6

[0128] It is implemented in the same manner as in Example 1. Compared with Example 1, polyglycolic acid A6 is used to replace polyglycolic acid A1.

[0129] Comparative Example 1

[0130] It is implemented in the same manner as in Example 1. Compared with Example 1, the dosage of the micro-crosslinked polymer D1 is adjusted to 0.1 part by weight, and the others remain unchanged.

[0131] Comparative Example 2

[0132] It is implemented in the same manner as in Example 1. Compared with Example 1, the micro-crosslinked polymer D5 is used to replace the micro-crosslinked polymer D1, and the others remain unchanged.

[0133] Comparative Example 3

[0134] It is implemented in the same manner as in Example 1. Compared with Example 1, the first stirring temperature in the preparation method is adjusted to 10°C.

[0135] Comparative Example 4

[0136] It is implemented in the same manner as in Example 1. Compared with Example 1, the micro-crosslinked polymer D is not added.

[0137] Comparative Example 5

[0138] It is implemented in the same manner as in Example 1. Compared with Example 1, 0.76 part by weight of the micro-crosslinked polymer D6 is used to replace the micro-crosslinked polymer D1.

[0139] Comparative Example 6

[0140] It is implemented in the same manner as in Example 1. Compared with Example 1, the uncrosslinked polymer D7 is used to replace the micro-crosslinked polymer D1.

[0141] Comparative Example 7

[0142] It is implemented in the same manner as in Example 1. Compared with Example 1, only the main emulsifier B1 is added, and the co-emulsifier C1 is not added.

[0143] Comparative Example 8

[0144] 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, the main emulsifier B1, the co-emulsifier C1, and the micro-crosslinked polymer D1 are added simultaneously.

[0145] For the specific dosages of each component, see Table 1.

[0146] Table 1

[0147]

[0148]

[0149] 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 for details.

[0150] Table 2

[0151]

[0152] It can be seen from Table 1 and Table 2 that compared with Comparative Example 1, in Example 1, the dosages of each component make the composition have good stability, thus resulting in high injectability. A large number of particles smoothly enter the reservoir core, and the pressure-bearing capacity is enhanced; compared with Comparative Example 2, in Example 1, the composition has good water solubility and stability and high pressure-bearing capacity; compared with Comparative Example 3, in Example 1, the components have good solubility, dispersibility and stability and good pressure-bearing capacity; in Comparative Example 4, no micro-crosslinked polymer is added, and in Comparative Example 5 and Comparative Example 6, the types and crosslinking degrees of the micro-crosslinked polymer D are adjusted respectively. The suspension stability of the composition particles in Example 1 is good compared with the compositions in the three examples, and thus the pressure-bearing capacity is high; compared with Comparative Example 7, in Example 1, the emulsifier component is omitted, the dispersibility is reduced, and finally the pressure-bearing capacity decreases; compared with Comparative Example 8, in Example 1, the feeding sequence makes the solubility of the micro-crosslinked polymer D in the composition appropriate, the suspension stability is good, and the pressure-bearing capacity increases.

[0153] 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 temporary plugging agent composition for oil well fracturing, characterized in that, The composition contains polyglycolic acid A, main emulsifier B, co-emulsifier C, micro-crosslinked polymer D and water; The micro-crosslinked polymer D is an acrylamide polymer; The crosslinking degree of the micro-crosslinked polymer D is 2-8%; Relative to 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 0.1-2 parts by weight, the content of co-emulsifier C is 0.05-1 part by weight, and the content of micro-crosslinked polymer D is 0.3-1 part by weight.

2. The composition according to claim 1, wherein Relative to 100 parts by weight of water, the content of polyglycolic acid A is 1-5 parts by weight, the content of main emulsifier B is 0.5-1.5 parts by weight, the content of co-emulsifier C is 0.2-0.8 part by weight, and the content of micro-crosslinked polymer D is 0.5-0.8 part by weight.

3. The composition according to claim 1 or 2, wherein The polyglycolic acid A is 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 80,000-130,000.

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 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.

5. The composition according to any one of claims 1-4, wherein, The crosslinking degree of the micro-crosslinked polymer D is 3-6%; 6. A preparation method of an oil well fracturing temporary plugging agent composition, characterized in that, It includes the following steps: (1) Add the micro-crosslinked polymer D to water and conduct the first stirring to obtain mixed solution I; (2) Add the main emulsifier B to the above mixed solution I and conduct the second stirring to obtain mixed emulsion II; (3) Add the co-emulsifier C to the above mixed emulsion II and conduct the third stirring to obtain mixed emulsion III; (4) Add the polyglycolic acid A to the above mixed emulsion III and conduct the fourth stirring to obtain the oil well fracturing temporary plugging agent composition; The micro-crosslinked polymer D is an acrylamide polymer; The crosslinking degree of the micro-crosslinked polymer D is 2-8%; Relative to 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 0.1-2 parts by weight, the content of co-emulsifier C is 0.05-1 part by weight, and the content of micro-crosslinked polymer D is 0.3-1 part by weight; The time of the first stirring is 30-150 min and the temperature is 20-60 °C.

7. The preparation method according to claim 6, wherein, Relative to 100 parts by weight of water, the content of polyglycolic acid A is 1-5 parts by weight, the content of main emulsifier B is 0.5-1.5 parts by weight, the content of co-emulsifier C is 0.2-0.8 part by weight, and the content of micro-crosslinked polymer D is 0.5-0.8 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 5-100 μm, preferably 20-80 μm; Preferably, the number-average molecular weight of the polyglycolic acid A is 50,000 to 150,000, preferably 80,000 to 130,000.

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 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.

10. The preparation method according to any one of claims 6-9, wherein, The crosslinking degree of the micro-crosslinked polymer D is 3% to 6%.

11. The preparation method according to any one of claims 6-10, wherein The first stirring time is 60 to 120 min, and the temperature is 30 to 50 °C; Preferably, the second stirring time is 10 to 40 min, and the temperature is 20 to 60 °C; more preferably, the second stirring time is 15 to 25 min, and the temperature is 30 to 50 °C; Preferably, the third stirring time is 10 to 40 min, and the temperature is 20 to 60 °C; more preferably, the third stirring time is 15 to 25 min, and the temperature is 30 to 50 °C; Preferably, the fourth stirring time is 10 to 30 min, and the temperature is 20 to 60 °C; more preferably, the fourth stirring time is 10 to 20 min, and the temperature is 30 to 50 °C.

12. An oil well fracturing temporary plugging agent composition prepared by the preparation method according to any one of claims 6-11.

13. The application of the oil well fracturing temporary plugging agent composition according to any one of claims 1-5 and 12 in high-temperature oil well fracturing.

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