A frozen solid gel temporary plugging agent and a preparation method thereof

Abstract

The application provides a frozen solid-state gel temporary plugging agent and a preparation method thereof. The frozen solid-state gel temporary plugging agent comprises a main agent and water, and the main agent comprises, in terms of weight parts, 85-96 parts of bentonite, 0.5-5 parts of an etherifying agent and 4-12 parts of a carbonate. The temporary plugging agent provided by the application has a long existence period, high stability, strong adhesion and can be firmly adsorbed on the oil pipe wall. After successful temporary plugging, the temporary plugging agent can bear a large pressure and has a high safety factor.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic temporary plugging technology, specifically relating to a cryogenic solid colloidal temporary plugging agent and its preparation method, and more particularly to a cryogenic solid colloidal temporary plugging agent with high pressure resistance and its preparation method. Background Technology

[0002] The wellhead assembly is a crucial channel for safe gas well production and a primary device for pressure control. However, as gas wells age, the wellhead assembly develops numerous safety hazards due to wear, corrosion, and aging. Failure to address these issues promptly can compromise safe gas well production, severely damage the surrounding environment, and threaten the lives of people and livestock. Replacing valves using conventional well-killing methods is time-consuming, costly, and difficult to restore production. Therefore, live valve replacement technology plays a vital role in replacing main control valves at the wellhead.

[0003] Cryogenic temporary plugging equipment and technology is a new technology developed for high-pressure gas well workover, mainly used for temporarily sealing the annulus and tubing during high-pressure gas well workover. The cryogenic temporary plugging technology involves injecting a plugging agent into the annulus and tubing through a cryogenic injection system. A freezing medium is used around the casing to gradually freeze the plugging agent from the outer casing into the tubing until it tightly bonds with the casing and tubing, forming a frozen bridge plug. This seals the tubing at the annulus, isolating the well pressure and allowing for safe replacement of the gas wellhead or some gate valves.

[0004] CN106833571A discloses a high-pressure cryogenic plugging agent and its preparation method. The agent is formed by freezing a high-pressure cryogenic plugging agent base slurry. The base slurry comprises the following components and their mass percentages: 5%-15% bentonite, 2%-4% biodegradable fiber, and 81%-93% water. The bentonite is any one or a mixture of more than one of sodium-based bentonite, calcium-based bentonite, and hydrogen-based bentonite. The biodegradable fiber is polylactic acid fiber, polyvinyl alcohol fiber, or a mixture of both. This invention utilizes the network structure formed by the biodegradable fiber to reduce leakage of the base slurry, thereby accelerating freezing. Simultaneously, it can improve the pressure resistance of the plugging agent, offering advantages such as simple formulation, low leakage rate, fast freezing speed, high pressure resistance, low cost, and convenient operation.

[0005] CN109652041A discloses a fracture-filled powdered temporary plugging agent and its preparation method. The powdered temporary plugging agent comprises ionic liquid-modified polyacrylonitrile, nonionic surfactant, polyacrylamide, gelatin, polyethylene vinyl acetate, bentonite, and carboxymethyl hydroxypropyl dual-derived guar gum. By weight, it comprises 25-35 parts of ionic liquid-modified polyacrylonitrile, 100-300 parts of nonionic surfactant, 50-80 parts of polyacrylamide, 20-50 parts of gelatin, 80-150 parts of polyethylene vinyl acetate, 250-350 parts of bentonite, and 100-220 parts of carboxymethyl hydroxypropyl dual-derived guar gum. It can form a filter cake in the formation, exhibiting a high plugging rate and good plugging effect. The surfactant it contains degrades with increasing temperature, which is beneficial for drainage and will not cause blockage or damage to the fracture.

[0006] Since sealing the gas wellhead is crucial for safe production, how to provide a temporary plugging agent with good sealing effect has become an urgent problem to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a cryogenic solid colloidal temporary plugging agent and its preparation method, particularly a cryogenic solid colloidal temporary plugging agent with high pressure resistance and its preparation method. The cryogenic solid colloidal temporary plugging agent provided by the present invention has an extended shelf life, high stability, and strong adhesion, enabling it to firmly adhere to the oil pipe wall. After successful temporary plugging, it can withstand significant pressure, exhibiting a high safety factor.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] On one hand, the present invention provides a cryogenic solid colloidal temporary plugging agent, which includes a main agent and water. The main agent includes, by weight, 85-96 parts of bentonite, 0.5-5 parts of etherifying agent and 4-12 parts of carbonate.

[0010] The number of parts of bentonite can be 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, or 96, etc.; the number of parts of etherifying agent can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5, etc.; and the number of parts of carbonate can be 4, 5, 6, 7, 8, 9, 10, 11, or 12, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0011] The above-mentioned specific composition of cryogenic solid colloidal temporary plugging agent has an extended shelf life, high stability, and strong adhesion, enabling it to firmly adhere to the oil pipe wall. After successful temporary plugging, it can withstand high pressure and has a high safety factor.

[0012] Preferably, the mass ratio of the main agent to water is 1:(0.5-0.9), such as 1:0.5, 1:0.6, 1:0.7, 1:0.8 or 1:0.9, but not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0013] Preferably, the bentonite includes any one or a combination of at least two of sodium-based bentonite, calcium-based bentonite, or hydrogen-based bentonite, such as a combination of sodium-based bentonite and calcium-based bentonite, a combination of calcium-based bentonite and hydrogen-based bentonite, or a combination of hydrogen-based bentonite and sodium-based bentonite, etc., but is not limited to the combinations listed above. Other combinations not listed above are also applicable.

[0014] Preferably, the bentonite is a combination of sodium-based bentonite, calcium-based bentonite, and hydrogen-based bentonite.

[0015] The aforementioned specific bentonite combination can further improve the sealing performance and pressure resistance of the product.

[0016] Preferably, the etherifying agent comprises monochloroacetic acid and / or cellulose.

[0017] Preferably, the etherifying agent is monochloroacetic acid and cellulose, and the mass ratio of monochloroacetic acid to cellulose is 1:(0.2-5), such as 1:0.2, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0018] Preferably, the cellulose includes any one or a combination of at least two of carboxymethyl cellulose, carboxymethyl hydroxymethyl cellulose, carboxymethyl methyl cellulose, and carboxymethyl hydroxyethyl cellulose, such as a combination of carboxymethyl cellulose and carboxymethyl hydroxymethyl cellulose, a combination of carboxymethyl hydroxymethyl cellulose and carboxymethyl methyl cellulose, or a combination of carboxymethyl methyl cellulose and carboxymethyl hydroxyethyl cellulose, etc., but is not limited to the combinations listed above. Other combinations not listed above are also applicable.

[0019] Preferably, the cellulose is a combination of carboxymethyl cellulose, carboxymethyl hydroxymethyl cellulose and carboxymethyl methyl cellulose.

[0020] The specific cellulose combination mentioned above can effectively improve the compressive strength of the product.

[0021] On the other hand, the present invention also provides a method for preparing the cryogenic solid colloidal temporary plugging agent as described above, the preparation method comprising the following steps:

[0022] The main agent is obtained by mixing bentonite, etherifying agent and carbonate, and then mixing and stirring with water to obtain the frozen solid colloidal temporary plugging agent.

[0023] Preferably, the stirring time is 15-20 hours, such as 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours, but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention provides a cryogenic solid colloidal temporary plugging agent with a specific composition, which has the characteristics of extended shelf life, high stability, and strong adhesion, and can be firmly adsorbed on the oil pipe wall. After successful temporary plugging, it can withstand high pressure and has a high safety factor. By selecting a specific combination of cellulose and bentonite, the plugging performance, pressure resistance and compressive strength of the product can be effectively improved. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.

[0027] In the following examples, the bentonite was purchased from Handan Jinan New Area Defu Bentonite Plant;

[0028] Cellulose was purchased from Sichuan Lanyang Daily Chemical Co., Ltd.

[0029] Example 1

[0030] This embodiment provides a cryogenic solid colloidal temporary plugging agent, the specific composition of which (by weight) is as follows:

[0031] The mass ratio of main agent to water is 1:0.7.

[0032] Main components: 30 parts sodium bentonite, 30 parts calcium bentonite, 30 parts hydrogen bentonite, 1.5 parts monochloroacetic acid, 0.5 parts carboxymethyl cellulose, 0.5 parts carboxymethyl hydroxymethyl cellulose, 0.5 parts carboxymethyl methyl cellulose, and 8 parts sodium carbonate.

[0033] The preparation method is as follows:

[0034] Sodium-based bentonite, calcium-based bentonite, hydrogen-based bentonite, monochloroacetic acid, carboxymethyl cellulose, carboxymethyl hydroxymethyl cellulose, carboxymethyl methyl cellulose, and sodium carbonate are mixed to obtain the main agent. The main agent is then slowly and evenly sprinkled into water and stirred continuously for 18 hours to obtain the temporary plugging agent.

[0035] Example 2

[0036] This embodiment provides a cryogenic solid colloidal temporary plugging agent, the specific composition of which (by weight) is as follows:

[0037] The mass ratio of main agent to water is 1:0.5.

[0038] Main components: 25 parts sodium bentonite, 30 parts calcium bentonite, 30 parts hydrogen bentonite, 0.084 parts monochloroacetic acid, 0.15 parts carboxymethyl cellulose, 0.15 parts carboxymethyl hydroxymethyl cellulose, 0.116 parts carboxymethyl methyl cellulose, and 4 parts sodium carbonate.

[0039] The preparation method is the same as in Example 1.

[0040] Example 3

[0041] This embodiment provides a cryogenic solid colloidal temporary plugging agent, the specific composition of which (by weight) is as follows:

[0042] The mass ratio of main agent to water is 1:0.9.

[0043] Main components: 30 parts sodium bentonite, 30 parts calcium bentonite, 36 parts hydrogen bentonite, 4.16 parts monochloroacetic acid, 0.3 parts carboxymethyl cellulose, 0.3 parts carboxymethyl hydroxymethyl cellulose, 0.24 parts carboxymethyl methyl cellulose, and 12 parts sodium carbonate.

[0044] The preparation method is the same as in Example 1.

[0045] Example 4

[0046] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of sodium-based bentonite and the reduction of its portion by distributing it proportionally to calcium-based and hydrogen-based bentonite, the composition is the same as in Example 1.

[0047] The preparation method is the same as in Example 1.

[0048] Example 5

[0049] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of calcium-based bentonite and the reduction of its portion by distributing it proportionally to sodium-based and hydrogen-based bentonite, the composition is the same as in Example 1.

[0050] The preparation method is the same as in Example 1.

[0051] Example 6

[0052] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of hydrogen-based bentonite and the reduction of its portion by proportional allocation to calcium-based and sodium-based bentonite, the composition is the same as in Example 1.

[0053] The preparation method is the same as in Example 1.

[0054] Example 7

[0055] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of calcium-based bentonite and hydrogen-based bentonite, and the reduction of the amount allocated to sodium-based bentonite, the composition is the same as that in Example 1.

[0056] The preparation method is the same as in Example 1.

[0057] Example 8

[0058] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of sodium-based bentonite and hydrogen-based bentonite, and the reduction of the amount allocated to calcium-based bentonite, the composition is the same as that in Example 1.

[0059] The preparation method is the same as in Example 1.

[0060] Example 9

[0061] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of calcium-based bentonite and sodium-based bentonite, and the reduction of the amount allocated to hydrogen-based bentonite, the composition is the same as that in Example 1.

[0062] The preparation method is the same as in Example 1.

[0063] Example 10

[0064] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of carboxymethyl cellulose and the reduction of the amount allocated to carboxymethyl hydroxymethyl cellulose and carboxymethyl methyl cellulose in proportion, the composition is the same as that of Example 1.

[0065] The preparation method is the same as in Example 1.

[0066] Example 11

[0067] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of carboxymethyl hydroxymethyl cellulose and the reduction of the amount allocated to carboxymethyl cellulose and carboxymethyl methyl cellulose in proportion, the composition is the same as that of Example 1.

[0068] The preparation method is the same as in Example 1.

[0069] Example 12

[0070] This embodiment provides a cryogenic solid colloidal temporary plugging agent. Except for the absence of carboxymethyl methyl cellulose and the reduction of the proportion allocated to carboxymethyl hydroxymethyl cellulose and carboxymethyl cellulose, the composition is the same as that of Example 1.

[0071] The preparation method is the same as in Example 1.

[0072] Example 13

[0073] This embodiment provides a cryogenic solid colloidal temporary plugging agent, whose composition is the same as that of Example 1, except that it does not contain carboxymethyl hydroxymethyl cellulose and carboxymethyl methyl cellulose, and a portion of which is allocated to carboxymethyl cellulose.

[0074] The preparation method is the same as in Example 1.

[0075] Example 14

[0076] This embodiment provides a cryogenic solid colloidal temporary plugging agent, whose composition is the same as that of Example 1, except that it does not contain carboxymethyl cellulose and carboxymethyl methyl cellulose, and a portion of which is allocated to carboxymethyl hydroxymethyl cellulose.

[0077] The preparation method is the same as in Example 1.

[0078] Example 15

[0079] This embodiment provides a cryogenic solid colloidal temporary plugging agent, whose composition is the same as that of Example 1, except that it does not contain carboxymethyl hydroxymethyl cellulose and carboxymethyl cellulose, and a portion of which is allocated to carboxymethyl methyl cellulose.

[0080] The preparation method is the same as in Example 1.

[0081] Compression resistance test:

[0082] The cryogenic solid colloidal temporary plugging agents provided in Examples 1-15 were respectively placed into containers with an inner diameter of 88.9 mm and a height of 10 cm, and allowed to solidify naturally for 24 hours. Their compressive strength was then measured using an SQ-1 pressure testing machine, and the results are as follows:

[0083]

[0084] The above data fully demonstrate that the product provided by the present invention has excellent compressive strength and pressure resistance; comparative examples 1 and 4-9 show that the present invention can effectively improve the compressive strength of the product by selecting specific bentonite; comparative examples 1 and 10-15 show that the present invention further improves the compressive strength of the product by selecting specific cellulose, which has significant advantages compared with other cellulose combinations.

[0085] The applicant declares that this invention illustrates the frozen solid colloidal temporary plugging agent and its preparation method through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

[0086] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. 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, and these simple modifications all fall within the protection scope of the present invention.

[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A frozen solid gelled temporary plugging agent, characterized in that, The frozen solid colloidal temporary plugging agent, by weight, has a specific composition in any one of the following three ways: (1) Mass ratio of main agent: water = 1:0.7, main agent: 30 parts sodium bentonite, 30 parts calcium bentonite, 30 parts hydrogen bentonite, 1.5 parts monochloroacetic acid, 0.5 parts carboxymethyl cellulose, 0.5 parts carboxymethyl hydroxymethyl cellulose, 0.5 parts carboxymethyl methyl cellulose, 8 parts sodium carbonate; (2) The mass ratio of main agent to water is 1:0.

5. The main agent consists of 25 parts sodium bentonite, 30 parts calcium bentonite, 30 parts hydrogen bentonite, 0.084 parts monochloroacetic acid, 0.15 parts carboxymethyl cellulose, 0.15 parts carboxymethyl hydroxymethyl cellulose, 0.116 parts carboxymethyl methyl cellulose, and 4 parts sodium carbonate. (3) The mass ratio of main agent to water is 1:0.

9. The main agent consists of 30 parts of sodium bentonite, 30 parts of calcium bentonite, 36 parts of hydrogen bentonite, 4.16 parts of monochloroacetic acid, 0.3 parts of carboxymethyl cellulose, 0.3 parts of carboxymethyl hydroxymethyl cellulose, 0.24 parts of carboxymethyl methyl cellulose, and 12 parts of sodium carbonate. The preparation method of the cryogenic solid colloidal temporary plugging agent is as follows: Sodium-based bentonite, calcium-based bentonite, hydrogen-based bentonite, monochloroacetic acid, carboxymethyl cellulose, carboxymethyl hydroxymethyl cellulose, carboxymethyl methyl cellulose, and sodium carbonate are mixed to obtain the main agent. The main agent is then slowly and evenly sprinkled into water and stirred continuously for 18 hours to obtain the temporary plugging agent.

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