A gel temporary plugging agent and its preparation method and application

Abstract

The present invention provides a gel temporary plugging agent and its preparation method and application, which belong to the field of oilfield chemical technology. The gel temporary plugging agent provided by the present invention has a three-dimensional network structure formed by cross-linking animal proteins, and can be degraded into linear polypeptide chains in acid under low temperature conditions, thereby achieving a temporary plugging effect; by introducing a reinforcing agent structural unit for enhancement, the plugging performance of the gel temporary plugging agent is ensured, so that it can achieve the plugging of low-temperature reservoirs. The results of the embodiment show that the hardness of the gel temporary plugging agent prepared by the present invention can reach 42.0N, the elasticity can reach 9.50mm, and the plugging pressure can reach 24.69MPa at a permeability of 1105.2mD; the degradation time can be controlled at 1.3 to 4.1d.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemistry, and in particular to a gel temporary plugging agent, a preparation method and an application thereof. Background Art

[0002] Acidizing is a petroleum engineering technique that uses acids to chemically dissolve formations, remove blockages, and restore or increase formation productivity. It is primarily used to increase well productivity during oilfield development. However, due to the significant heterogeneity of formations, conventional acidizing processes are prone to acid "fingering" into high-permeability zones, resulting in poor acidizing results in low-permeability reservoirs and an inability to effectively remove blockages and increase production.

[0003] To address these issues, temporary plugging and acidizing technology was developed. This technology aims to temporarily plug the high-permeability layer, followed by acidizing to increase the permeability of the low-permeability layer and the plugged oil layer, thereby achieving uniform acid distribution. In temporary plugging and acidizing technology, the selection of the temporary plugging agent is crucial.

[0004] Common temporary plugging agents include fiber temporary plugging agents and gel temporary plugging agents. Fiber temporary plugging agents are made from chemical fibers with high aspect ratios and their modified products, such as polyvinyl alcohol fibers, polylactic acid fibers, and polyester fibers. These fiber temporary plugging agents are flexible, malleable, and have high aspect ratios, forming effective filter structures. However, they tend to aggregate and clog pipelines, and are prone to dispersal during field applications, resulting in high costs. Gel temporary plugging agents, on the other hand, can be made into granules, preventing pipeline clogging and making them easier to store and transported by fluids into pores or fractures.

[0005] Currently, most gel temporary plugging agents, based on partially hydrolyzed polyacrylamide, can only self-degrade at moderately high temperatures (70-180°C) or in high-salinity environments, failing to meet the degradation requirements of low-temperature reservoirs (<60°C). Although prior art patent CN111621273A discloses a fast-dissolving temporary plugging agent suitable for low temperatures, its actual applicable temperature is 85-96°C, still considered moderately high. Summary of the Invention

[0006] The object of the present invention is to provide a gel temporary plugging agent and a preparation method and application thereof. The gel temporary plugging agent provided by the present invention can be used for temporary plugging of low-temperature reservoirs at 20 to 60°C.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a gel temporary plugging agent, which contains an animal protein structural unit, an enhancer structural unit and a cross-linking structural unit. The animal protein structural unit and the enhancer structural unit are chemically bonded through the cross-linking structural unit to form a three-dimensional network structure.

[0009] Preferably, the animal protein in the animal protein structural unit includes one of bovine serum albumin and whey protein.

[0010] Preferably, the enhancer structural unit is an acrylamide structural unit or an acrylamide sulfonic acid structural unit.

[0011] Preferably, the mass ratio of the animal protein structural unit to the enhancer structural unit is (0.4-2):1.

[0012] Preferably, the cross-linking structural unit is formed by N,N-methylenebisacrylamide, dimethyldiallylammonium chloride or divinylbenzene.

[0013] The present invention also provides a method for preparing the gel temporary plugging agent described in the above technical solution, comprising:

[0014] The animal protein, gelation accelerator, enhancer, cross-linking agent, gelation inducer and water are mixed and gelled to obtain a gel temporary plugging agent.

[0015] Preferably, the gelling accelerator comprises vinasse press liquor.

[0016] Preferably, the raw materials are calculated by mass percentage as follows: animal protein 2% to 10%, gelation accelerator 8% to 30%, enhancer 2% to 10%, cross-linking agent 0.5‰ to 2‰, gelation inducer 0.5% to 2% and the balance water.

[0017] Preferably, the gelling temperature is 85-90° C., and the gelling time is 1.5-2 hours.

[0018] The present invention also provides the use of the gel temporary plugging agent described in the above technical solution or the gel temporary plugging agent prepared by the preparation method described in the above technical solution in temporary plugging of low-temperature reservoirs.

[0019] The present invention provides a gel temporary plugging agent, which contains an animal protein structural unit, an enhancer structural unit and a cross-linking structural unit. The animal protein structural unit and the enhancer structural unit are chemically bonded to form a three-dimensional network structure through the cross-linking structural unit. The gel temporary plugging agent provided by the present invention has a three-dimensional network structure formed by cross-linking of animal proteins, which can be degraded into linear polypeptide chains in acid solution under low temperature conditions, thereby achieving a temporary plugging effect; by introducing the enhancer structural unit for enhancement, the plugging performance of the gel temporary plugging agent is ensured, so that it can achieve the plugging of low-temperature reservoirs. The results of the embodiment show that the hardness of the gel temporary plugging agent prepared by the present invention can reach 42.0N, the elasticity can reach 9.50mm, and the plugging pressure can reach 24.69MPa at a permeability of 1105.2mD; the degradation time can be controlled at 1.3 to 4.1d. DETAILED DESCRIPTION

[0020] The present invention provides a gel temporary plugging agent, which contains an animal protein structural unit, an enhancer structural unit and a cross-linking structural unit. The animal protein structural unit and the enhancer structural unit are chemically bonded through the cross-linking structural unit to form a three-dimensional network structure.

[0021] The gel temporary plugging agent provided by the present invention contains animal protein structural units. In the present invention, the animal protein structural units formed by cross-linking animal proteins have a three-dimensional network structure and can be degraded into linear polypeptide chains in acid solution under low temperature conditions, thereby achieving a temporary plugging effect.

[0022] In the present invention, the animal protein in the animal protein structural unit preferably includes one of bovine serum albumin and whey protein. The present invention limits the type of animal protein to ensure more sufficient cross-linking to obtain the animal protein structural unit.

[0023] The gel temporary plugging agent provided by the present invention contains a reinforcing agent structural unit. In this invention, the reinforcing agent unit formed by cross-linking the reinforcing agent can enhance the hardness and elasticity of the gel temporary plugging agent as well as the plugging pressure, thereby enhancing the plugging strength, ensuring the plugging performance of the gel temporary plugging agent, enabling it to plug low-temperature reservoirs, and shortening the gelling time of the gel temporary plugging agent.

[0024] In the present invention, the reinforcing agent structural unit is preferably an acrylamide structural unit or an acrylamide sulfonic acid structural unit. By limiting the type of reinforcing agent structural unit, the present invention can more fully improve the hardness, elasticity, and plugging pressure of the gel temporary plugging agent and shorten the gelling time of the gel temporary plugging agent.

[0025] In the present invention, the acrylamide sulfonic acid in the acrylamide sulfonic acid structural unit preferably includes one of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2-acrylamido-2-phenylethanesulfonic acid (AMSS), 2-acrylamidododecylsulfonic acid (ADS), and 2-acrylamidotetradecylsulfonic acid (ATS). By limiting the acrylamide sulfonic acid in the acrylamide sulfonic acid structural unit, the present invention further improves the hardness, elasticity, and plugging pressure of the gel temporary plugging agent and shortens its gelation time.

[0026] In the present invention, the mass ratio of the animal protein structural unit to the enhancer structural unit is preferably (0.2-5):1, more preferably (1-3):1. By limiting the mass ratio of the animal protein structural unit to the enhancer structural unit, the present invention further ensures that the gel temporary plugging agent has a short gelling time, high plugging strength, and controllable degradation time.

[0027] The gel temporary plugging agent provided by the present invention contains a cross-linked structural unit. In the present invention, the cross-linked structural unit chemically bonds the animal protein structural unit and the reinforcing agent structural unit to form a three-dimensional network structure, thereby achieving plugging of the low-temperature reservoir.

[0028] In the present invention, the crosslinking agent in the crosslinking structural unit is preferably formed by N,N-methylenebisacrylamide, dimethyldiallylammonium chloride or divinylbenzene. By limiting the type of crosslinking agent in the crosslinking structural unit, the present invention allows the animal protein structural unit and the enhancer structural unit to more fully form a three-dimensional network structure.

[0029] The gel temporary plugging agent provided by the present invention has a three-dimensional network structure formed by cross-linking animal proteins, and can be degraded into linear polypeptide chains in acid under low temperature conditions, thereby achieving a temporary plugging effect; by introducing a reinforcing agent structural unit for reinforcement, the plugging performance of the gel temporary plugging agent is guaranteed, enabling it to achieve plugging of low-temperature reservoirs.

[0030] The present invention also provides a method for preparing the above-mentioned gel temporary plugging agent, comprising:

[0031] The animal protein, gelation accelerator, enhancer, cross-linking agent, gelation inducer and water are mixed and gelled to obtain a gel temporary plugging agent.

[0032] The invention mixes animal protein, a gelling accelerator, a reinforcing agent, a cross-linking agent, a gelling inducing agent and water and then performs gelling to obtain a gel temporary plugging agent.

[0033] In the present invention, the gelling accelerator is preferably vinasse press filtrate. The present invention further shortens the gelling time of animal protein by limiting the type of gelling accelerator.

[0034] In the present invention, the components of the vinasse press liquid preferably include 13.4 g / 100 g of total peptides, 153597.00 to 162754.00 mg / L of lactic acid, 0.29 to 0.33 g / 100 mL of aspartic acid, 0.13 to 0.18 g / 100 mL of threonine, 0.23 to 0.25 g / 100 mL of serine, 0.61 to 0.67 g / 100 mL of glutamic acid, 0.18 to 0.25 g / 100 mL of glycine, 0.38 to 0.41 g / 100 mL of alanine, 0.044 to 0.058 g / 100 mL of valine. The present invention limits the components of the vinasse press filtrate to ensure that the animal protein can more fully promote the formation of gel.

[0035] The present invention does not specifically limit the preparation method of the vinasse filtrate press, and any method for preparing vinasse filtrate press known in the art can be used. In the present invention, the preparation method of the vinasse filtrate press preferably comprises the following steps:

[0036] 1) mixing yellow water produced in the winemaking process with ethanol, and then heating and purifying the mixture to obtain purified yellow water;

[0037] 2) Concentrating the purified yellow water obtained in step 1) to obtain a vinasse press filtrate.

[0038] The invention mixes yellow water generated in the wine-making process with ethanol, heats the mixture, and purifies the mixture to obtain purified yellow water.

[0039] The present invention has no particular limitation on the extraction of the yellow water produced during the winemaking process, and any extraction method known in the art can be used. In the present invention, the extraction of the yellow water produced during the winemaking process is preferably performed by filtration.

[0040] In the present invention, the mass ratio of yellow water produced during the winemaking process to ethanol is preferably 1: (2-4), more preferably 1: 3. The present invention ensures more complete purification of the yellow water produced during the winemaking process by limiting the mass ratio of yellow water produced during the winemaking process to ethanol.

[0041] The present invention has no special limitation on the mixing of the yellow water and ethanol produced in the wine-making process, and any mixing method well known in the art can be used.

[0042] In the present invention, the temperature for the heating and purification is preferably 105-110°C; and the time for the heating and purification is preferably 30-45 minutes. The present invention limits the temperature and time for the heating and purification to ensure that the yellow water produced during the winemaking process is more fully dissolved and that impurities in the yellow water are more fully removed.

[0043] After heating and purification, the present invention preferably filters and cools the solution after heating and purification in sequence to obtain purified yellow water.

[0044] The present invention has no particular limitation on the filtration, and any filtration method well known in the art may be used.

[0045] In the present invention, the cooling is preferably to cool the filtered solution to 80-90°C.

[0046] After obtaining the purified yellow water, the present invention concentrates the purified yellow water to obtain vinasse press filtrate.

[0047] In the present invention, the concentration temperature is preferably 90-95° C. In the present invention, the concentration is preferably stopped when the solid content is 50%-53%.

[0048] In the present invention, the gelation inducer is preferably potassium persulfate. The present invention limits the type of the gelation inducer to ensure more complete gelation.

[0049] In the present invention, the raw materials are preferably calculated by mass percentage as follows: 2% to 10% animal protein, 8% to 30% gelation accelerator, 2% to 10% enhancer, 0.5‰ to 2‰ cross-linking agent, 0.5% to 2% gelation inducer and the balance water.

[0050] In the present invention, the raw material of the gel temporary plugging agent preferably includes 2% to 10% animal protein, more preferably 6% to 8% by mass. The present invention further improves the temporary plugging performance by limiting the content of animal protein.

[0051] In the present invention, the raw materials of the temporary gel plugging agent preferably include 8% to 30% by mass, more preferably 10 to 20% by mass of the gelling accelerator. The present invention further promotes the gelling of animal protein by limiting the content of the gelling accelerator.

[0052] In the present invention, the raw materials of the gel temporary plugging agent preferably include, by weight percentage, 2% to 10% of the reinforcing agent, more preferably 4% to 8%. By limiting the content of the reinforcing agent, the present invention further improves the hardness, elasticity, and plugging pressure of the prepared gel temporary plugging agent, thereby improving the plugging performance and further shortening the gelling time of the gel temporary plugging agent.

[0053] In the present invention, the raw materials of the temporary gel plugging agent preferably include, by mass percentage, 0.5‰ to 2‰ of a crosslinking agent, more preferably 1‰ to 1.5‰. By limiting the amount of crosslinking agent added, the present invention ensures that the animal protein structural units and the reinforcing agent structural units more fully form a three-dimensional network structure, thereby improving the temporary plugging performance of the temporary gel plugging agent.

[0054] In the present invention, the raw materials of the temporary gel plugging agent preferably include 0.5% to 2% of gelling inducer, more preferably 1% to 1.5% by mass. The present invention limits the amount of gelling inducer added to ensure a more complete reaction between the animal protein, the reinforcing agent, and the cross-linking agent.

[0055] In the present invention, the raw materials of the temporary gel plugging agent preferably include a balance of water by mass percentage. The present invention limits the amount of water added to ensure that the reactants are more fully dissolved and thus react more fully.

[0056] In the present invention, the mixing of the animal protein, gelation accelerator, enhancer, crosslinker, gelation inducer and water is preferably carried out under stirring. In the present invention, the stirring rate is preferably 300 to 600 r / s, more preferably 400 r / s.

[0057] In the present invention, the gelling temperature is preferably 85-90° C. and the gelling time is preferably 1.5-2 hours. The present invention limits the gelling temperature and time to ensure that the animal protein fully forms a gel.

[0058] After the gelation is completed, the present invention preferably crushes the gelled product to obtain a temporary gel plugging agent.

[0059] In the present invention, the particle size of the gel temporary plugging agent is preferably 1 to 3 mm. By limiting the particle size of the gel temporary plugging agent, the present invention is more conducive to entering the low-temperature reservoir and achieving temporary plugging of the low-temperature reservoir.

[0060] The present invention has no particular limitation on the crushing equipment, and any crushing equipment well known in the art may be used.

[0061] The preparation method of the gel temporary plugging agent provided by the present invention comprises the following steps: mixing animal protein, a gelling accelerator, a reinforcing agent, a cross-linking agent, a gelling inducer and water, and then fully gelling at a certain temperature to obtain the gel temporary plugging agent.

[0062] The present invention also provides the use of the gel temporary plugging agent or the gel temporary plugging agent prepared by the above preparation method in temporary plugging of low-temperature reservoirs.

[0063] In the present invention, when the low-temperature reservoir is a fracture or near-wellbore zone, a gel temporary plugging agent is preferably mixed with a carrier fluid and injected into the bottom layer. In the present invention, the mass percentage of the gel temporary plugging agent is preferably 5% to 15% of the total mass of the gel temporary plugging agent and the carrier fluid. The carrier fluid is not particularly limited in the present invention; any carrier fluid known in the art can be used.

[0064] In the present invention, when the temporary plugging of the warm reservoir is in a fracture or deep in the formation, it is preferred that the raw materials for preparing the gel temporary plugging agent are mixed and then injected into the formation to form gel.

[0065] The gel temporary plugging agent provided by the present invention can be used for temporary plugging of low-temperature reservoirs at 20 to 60°C.

[0066] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0067] Example 1

[0068] A gel temporary plugging agent is composed of a bovine serum albumin structural unit, an acrylamide enhancer structural unit and a cross-linked structural unit formed by N,N'-methylenebisacrylamide. The animal protein structural unit and the enhancer structural unit are chemically bonded through the cross-linked structural unit to form a three-dimensional network structure; the mass ratio of the animal protein structural unit to the enhancer structural unit is 0.25:1.

[0069] The preparation method of the above-mentioned gel temporary plugging agent consists of the following steps:

[0070] Calculated by mass percentage, 2% bovine serum albumin, 20% vinasse filtrate, 8% acrylamide enhancer, 0.5% N,N'-methylenebisacrylamide cross-linker, 3‰ ammonium persulfate gelling inducer and the balance water were stirred and mixed at 400 r / s, reacted at 85°C for 1.5 hours to form gel, and then crushed to obtain a 0.83mm-0.18mm gel temporary plugging agent.

[0071] Example 2

[0072] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 4%, and the rest is the same as embodiment 1.

[0073] Example 3

[0074] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 6%, and the rest is the same as embodiment 1.

[0075] Example 4

[0076] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 8%, and the rest is the same as embodiment 1.

[0077] Example 5

[0078] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 10%, and the rest is the same as embodiment 1.

[0079] Example 6

[0080] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 2% whey protein, and the rest is the same as embodiment 1.

[0081] Example 7

[0082] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 4% whey protein, and the rest is the same as embodiment 1.

[0083] Example 8

[0084] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 6% whey protein, and the rest is the same as embodiment 1.

[0085] Example 9

[0086] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 8% whey protein, and the rest is the same as embodiment 1.

[0087] Example 10

[0088] The difference between this embodiment and embodiment 1 is that the 2% bovine serum albumin in embodiment 1 is changed to 10% whey protein, and the rest is the same as embodiment 1.

[0089] 2 g of the gel temporary plugging agent prepared in Examples 1 to 10 was placed under acidification conditions of 60° C. and 50 mL of 20% hydrochloric acid. The degradation time was set to the time when the mass was degraded to less than 0.1 g. The degradation properties of the gel temporary plugging agent prepared in Examples 1 to 10 were obtained, as shown in Table 1.

[0090] Table 1 Degradation performance of the gel temporary plugging agent prepared in Examples 1 to 10

[0091] serial number Bovine serum albumin content Degradation time / D serial number Whey protein content Degradation time / D Example 1 2％ 1.3 Example 6 2％ 1.6 Example 2 4％ 2.2 Example 7 4％ 2.4 Example 3 6％ 3.2 Example 8 6％ 3.7 Example 4 8％ 3.6 Example 9 8％ 4.1 Example 5 10％ 4.1 Example 10 10％ 4.7

[0092] As shown in Table 1, the degradation time of the gel temporary plugging agent gradually increases with increasing BSA or whey protein content. The degradation time of the gel temporary plugging agent prepared with the same BSA content is shorter than that of whey protein. Therefore, the degradation time can be adjusted by regulating the BSA or whey protein content.

[0093] Example 11

[0094] A gel temporary plugging agent is composed of a bovine serum albumin structural unit, an acrylamide enhancer structural unit and a cross-linked structural unit formed by N,N'-methylenebisacrylamide. The animal protein structural unit and the enhancer structural unit are chemically bonded through the cross-linked structural unit to form a three-dimensional network structure; the mass ratio of the animal protein structural unit to the enhancer structural unit is 1.6:1.

[0095] The preparation method of the above-mentioned gel temporary plugging agent consists of the following steps:

[0096] Calculated by mass percentage, 8% bovine serum albumin, 20% vinasse filtrate, 5% acrylamide enhancer, 0.25% N,N'-methylenebisacrylamide cross-linker, 3‰ gelation inducer and water were stirred at 400 r / s, and then placed in a blue-capped bottle in an 80°C water bath for gelation to obtain a gel temporary plugging agent.

[0097] Example 12

[0098] The difference between this embodiment and embodiment 11 is that the 5% enhancer in embodiment 11 is changed to 10% enhancer, and the rest is the same as embodiment 11.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 11 is that the 5% enhancer in Example 11 is changed to 15% enhancer, and the rest is the same as Example 11.

[0101] Comparative Example 2

[0102] The difference between this comparative example and Example 11 is that the 5% enhancer in Example 11 is changed to 20% enhancer, and the rest is the same as Example 11.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 11 is that the 5% enhancer in Example 11 is changed to 25% enhancer, and the rest is the same as Example 11.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 11 is that the 5% enhancer in Example 11 is changed to 30% enhancer, and the rest is the same as Example 11.

[0107] The blue-capped bottles used for gelling in Examples 11 to 12 and Comparative Examples 1 to 4 were inverted at regular intervals, and the time when the reaction solution lost its ability to flow was defined as the gelling time. The results are shown in Table 2.

[0108] Table 2 Gelation time table of the gel temporary plugging agent reaction solution of Examples 11 to 12 and Comparative Examples 1 to 4

[0109] serial number Enhancer content Gelation time / min Example 11 5％ 5.5 Example 12 10％ 5.2 Comparative Example 1 15％ 4.8 Comparative Example 2 20％ 4.0 Comparative Example 3 25％ 3.7 Comparative Example 4 30％ 3.5

[0110] It can be seen from Table 2 that as the concentration of the enhancer increases, the gelation time decreases. By changing the concentration of the enhancer, the gelation time can be controlled within a certain range.

[0111] Example 13

[0112] A gel temporary plugging agent is composed of a bovine serum protein structural unit, an acrylamide enhancer structural unit and a cross-linked structural unit formed by N,N'-methylenebisacrylamide. The bovine serum protein structural unit and the enhancer structural unit are chemically bonded through the cross-linked structural unit to form a three-dimensional network structure; the mass ratio of the animal protein structural unit to the enhancer structural unit is 1:1.

[0113] The preparation method of the above-mentioned gel temporary plugging agent consists of the following steps:

[0114] Calculated by mass percentage, 2% bovine serum albumin, 20% vinasse filtrate, 2% acrylamide enhancer, 0.15% N,N'-methylenebisacrylamide cross-linker, 1.5‰ ammonium persulfate gelling inducer and water were stirred and mixed at 400 r / s, and reacted at 85°C for 2 hours to form a gel, thereby obtaining a 0.83mm-0.18mm gel temporary plugging agent.

[0115] Example 14

[0116] The difference between this embodiment and embodiment 13 is that the 2% enhancer in embodiment 13 is changed to 4% enhancer, and the rest is the same as embodiment 13.

[0117] Example 15

[0118] The difference between this embodiment and embodiment 13 is that the 2% enhancer in embodiment 13 is changed to 6% enhancer, and the rest is the same as embodiment 13.

[0119] Example 16

[0120] The difference between this embodiment and embodiment 13 is that the 2% enhancer in embodiment 13 is changed to 8% enhancer, and the rest is the same as embodiment 13.

[0121] Example 17

[0122] The difference between this embodiment and embodiment 13 is that the 2% enhancer in embodiment 13 is changed to 10% enhancer, and the rest is the same as embodiment 13.

[0123] Comparative Example 5

[0124] The difference between this comparative example and Example 13 is that the 2% enhancer in Example 13 is changed to 0% enhancer, and the rest is the same as Example 13.

[0125] The temporary plugging gels prepared in Examples 13 to 17 and Comparative Example 5 were cut into rectangular gels with a length of 4 cm, a width of 3 cm, and a height of 2 cm using scissors. These were then tested and analyzed using a TAXT PLUS texture analyzer. The analysis results are shown in Table 3.

[0126] Table 3 Hardness and elasticity data of the gel temporary plugging agent obtained in Examples 13 to 17 and Comparative Example 1

[0127] serial number Enhancer content Hardness / min Elasticity / mm Example 13 2％ 19.8 4.87 Example 14 4％ 40.0 7.76 Example 15 6％ 42.0 9.50 Example 16 8％ 39.3 9.08 Example 17 10％ 32.3 7.92 Comparative Example 5 0％ 16.7 3.49

[0128] As shown in Table 3, compared with Comparative Example 5 in which no reinforcing agent was added, the hardness and elasticity of the temporary plugging gel agents prepared in Examples 13 to 17 both showed a trend of first decreasing and then increasing with increasing reinforcing agent content, and when the reinforcing agent concentration was 6%, the hardness and elasticity of the temporary plugging gel agents were the highest. Therefore, by changing the reinforcing agent content, the hardness and elasticity of the temporary plugging gel agents can be controlled within a certain range.

[0129] Example 18

[0130] A gel temporary plugging agent is composed of a bovine serum albumin structural unit, an acrylamide enhancer structural unit and a cross-linked structural unit formed by N,N'-methylenebisacrylamide. The bovine serum albumin structural unit and the acrylamide enhancer structural unit are chemically bonded through the cross-linked structural unit to form a three-dimensional network structure; the mass ratio of the animal protein structural unit to the enhancer structural unit is 4:1.

[0131] The preparation method of the above-mentioned gel temporary plugging agent consists of the following steps:

[0132] Calculated by mass percentage, 8% bovine serum albumin, 20% vinasse filtrate, 2% acrylamide enhancer, 0.5% N,N'-methylenebisacrylamide cross-linker, 3‰ ammonium persulfate gelling inducer and the balance water were stirred and mixed at 400 r / s, and then injected into a sand-filled tube with a permeability of 1111.4 mD. Then, both ends of the sand-filled tube were sealed with plastic wrap and placed at 60°C for gelling to obtain a gel temporary plugging agent.

[0133] Example 19

[0134] The difference between this embodiment and embodiment 18 is that the 2% enhancer in embodiment 18 is changed to 4% enhancer; the permeability of 1111.4 mD is changed to 1087.4 mD, and the rest is the same as embodiment 18.

[0135] Example 20

[0136] The difference between this embodiment and embodiment 18 is that the 2% enhancer in embodiment 18 is changed to 6% enhancer; the permeability of 1111.4 mD is changed to 1105.2 mD, and the rest is the same as embodiment 18.

[0137] Example 21

[0138] The difference between this embodiment and embodiment 18 is that the 2% enhancer in embodiment 18 is changed to 8% enhancer; the permeability of 1111.4 mD is changed to 1119.7 mD, and the rest is the same as embodiment 18.

[0139] Example 22

[0140] The difference between this embodiment and embodiment 18 is that the 2% enhancer in embodiment 18 is changed to 10% enhancer; the permeability of 1111.4 mD is changed to 1056.9 mD, and the rest is the same as embodiment 18.

[0141] Comparative Example 6

[0142] The difference between this comparative example and Example 18 is that the 2% enhancer in Example 18 is changed to 0% enhancer; the permeability of 1111.4 mD is changed to 1095.2 mD, and the rest is the same as Example 18.

[0143] The present invention uses water flooding to test the plugging performance of the gel temporary plugging agent, and monitors and records the pressure changes in real time. The plugging performance results of the gel temporary plugging agents prepared in Examples 18 to 22 and Comparative Example 6 for sand-filled pipes with different permeabilities are shown in Table 4.

[0144] Table 4 Plugging performance of the gel temporary plugging agents prepared in Examples 18 to 22 and Comparative Example 6 for sand-filled pipes with different permeabilities

[0145]

[0146]

[0147] As shown in Table 4, compared with Comparative Example 6 in which no enhancer was added, the plugging pressure of the gel temporary plugging agents prepared in Examples 18 to 22 first decreased and then increased with increasing enhancer content, and the plugging pressure of the temporary plugging agent was the highest when the enhancer concentration was 6%. Therefore, the plugging pressure of the gel temporary plugging agent can be controlled within a certain range by changing the enhancer content.

[0148] In conclusion, the gel temporary plugging agent prepared by the present invention can be used for temporary plugging of low-temperature reservoirs at 20-60°C.

[0149] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A gel temporary plugging agent comprising an animal protein structural unit, a reinforcing agent structural unit, and a cross-linking structural unit, wherein the animal protein structural unit and the reinforcing agent structural unit are chemically bonded via the cross-linking structural unit to form a three-dimensional network structure; the animal protein in the animal protein structural unit comprises one of bovine serum albumin and whey protein; the reinforcing agent structural unit is an acrylamide structural unit or an acrylamide sulfonic acid structural unit; and the cross-linking structural unit is formed from N,N-methylenebisacrylamide, dimethyldiallylammonium chloride, or divinylbenzene; The preparation method of the gel temporary plugging agent comprises: The animal protein, gelation accelerator, enhancer, cross-linking agent, gelation inducer and water are mixed and gelled to obtain a gel temporary plugging agent; The raw materials are calculated by mass percentage as follows: animal protein 2%~10%, gelation accelerator 8%~30%, enhancer 2%~10%, cross-linking agent 0.5‰~2‰, gelation inducer 0.5%~2% and the balance water.

2. The gel temporary plugging agent according to claim 1, characterized in that: The mass ratio of the animal protein structural unit to the enhancer structural unit is (0.2~5):

1.

3. A method for preparing the gel temporary plugging agent according to any one of claims 1 to 2, comprising: The animal protein, gelation accelerator, enhancer, cross-linking agent, gelation inducer and water are mixed and gelled to obtain a gel temporary plugging agent.

4. The preparation method according to claim 3, characterized in that The gelling accelerator includes wine lees press liquid.

5. The preparation method of the gel temporary plugging agent according to claim 3, characterized in that: The gelling temperature is 85-90° C., and the gelling time is 1.5-2 hours.

6. Use of the gel temporary plugging agent according to any one of claims 1 to 2 or the gel temporary plugging agent prepared by the preparation method according to any one of claims 3 to 5 in temporary plugging of low-temperature reservoirs.

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