A differential pressure activated plugging agent for oil and gas wells

Abstract

The present application relates to the technical field of oil and gas field development, and proposes a differential pressure activated plugging agent for oil and gas well, which comprises the following raw materials in parts by mass: natural latex 20-40 parts, vulcanizing agent 0.1-0.5 parts, acid anhydride compound modified mica sheet 5-15 parts, activator 0.2-2 parts, terminating agent 5-10 parts, and water 60-80 parts. Through the above technical solution, the problems of low strength and poor high-temperature aging resistance of the differential pressure activated plugging agent in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and more specifically, to a differential pressure activation plugging agent for oil and gas wells. Background Technology

[0002] In the process of oil and gas field development, wellbore leakage has become an increasingly prominent problem. Wellbore leakage not only increases the development cost and risks of oil and gas fields, but also affects subsequent construction and production, seriously hindering the normal development and production of oil and gas wells. It has become an urgent problem to be solved in the field of oil and gas field development.

[0003] For wellbore plugging, commonly used plugging techniques include gel plugging, cement plugging, and resin plugging. However, these techniques have drawbacks such as low toughness and brittleness after curing, low pressure resistance and anti-channeling strength after plugging, inability of the solid to form a strong bond with the wellbore after plugging, and short duration of the sealing effect.

[0004] To address the aforementioned problems with commonly used plugging techniques, a differential pressure activated plugging agent, also known as a differential pressure activated sealant, has been developed. Its plugging mechanism involves physical and chemical reactions to form a plugging layer and deposits, thereby sealing the leaking pores. After injection, the plugging agent flows into the leaking channel with the medium. As the fluid pressure decreases, the plugging agent forms a plugging layer at the leak point, achieving a sealing effect. Any remaining plugging agent can continue to flow within the oil and gas well tubing, without affecting normal oil and gas well production.

[0005] Currently, most pressure differential activation plugging agents developed use rubber latex, but they suffer from low strength and poor high-temperature aging resistance. Summary of the Invention

[0006] This invention proposes a differential pressure activation plugging agent for oil and gas wells, which solves the problems of low strength and poor high-temperature aging resistance of differential pressure activation plugging agents in related technologies.

[0007] The technical solution of the present invention is as follows:

[0008] A differential pressure activation plugging agent for oil and gas wells comprises the following raw materials in parts by weight: 20-40 parts natural latex, 0.1-0.5 parts vulcanizing agent, 5-15 parts modified mica flakes with acid anhydride compound, 0.2-2 parts activator, 5-10 parts terminator, and 60-80 parts water.

[0009] As a further technical solution, the raw materials for the acid anhydride compound modified mica sheet include an acid anhydride compound and mica sheet in a mass ratio of 1~3:20.

[0010] As a further technical solution, the particle size of the mica sheet is 20-80 mesh.

[0011] As a further technical solution, the anhydride compound includes one or two of 3,4,5,6-tetrahydrophthalic anhydride and 2,3-diphenylmaleic anhydride.

[0012] As a further technical solution, the anhydride compound is composed of 3,4,5,6-tetrahydrophthalic anhydride and 2,3-diphenylmaleic anhydride in a mass ratio of 1:3 to 3:1.

[0013] As a further technical solution, the preparation method of the acid anhydride compound modified mica sheet includes the following steps: dissolving the acid anhydride compound in a solvent, adding it dropwise to the mica sheet, grinding, and drying to obtain the acid anhydride compound modified mica sheet.

[0014] As a further technical solution, the solvent includes one or both of N,N-dimethylformamide and ethanol.

[0015] As a further technical solution, the dripping rate is 0.5~3 mL / min.

[0016] As a further technical solution, the vulcanizing agent is a peroxide.

[0017] As a further technical solution, the vulcanizing agent is benzoyl peroxide.

[0018] As a further technical solution, the activator is an inorganic salt; the terminator is a surfactant.

[0019] As a further technical solution, the activator is one or more of sodium chloride, magnesium chloride, and magnesium sulfate;

[0020] The terminator is one or more of the surfactants OP-10, OP-40, and Gemini1231.

[0021] This invention also proposes a method for preparing a differential pressure activation and plugging agent for oil and gas wells, comprising the following steps: mixing natural latex, acid anhydride-modified mica flakes, a vulcanizing agent and water, adding an activator while stirring, and finally adding a terminator to obtain the differential pressure activation and plugging agent for oil and gas wells.

[0022] The working principle and beneficial effects of this invention are as follows:

[0023] 1. The anhydride-modified mica flakes in this invention can enhance the activity of the mica flakes, allowing them to function better in differential pressure activated plugging agents, blocking and embedding into residual micro-gaps, thereby improving the strength of the cured differential pressure activated plugging agent. Furthermore, in the high-temperature downhole environment, the anhydride-modified mica flakes will also react with natural latex, further improving the strength of the cured differential pressure activated plugging agent and enhancing its resistance to high-temperature aging.

[0024] 2. This invention uses 3,4,5,6-tetrahydrophthalic anhydride and 2,3-diphenylmaleic anhydride in a mass ratio of 1:3 to 3:1 as anhydride compounds to modify mica sheets, thereby further improving the strength and high-temperature aging resistance of the pressure differential activated sealing agent after curing. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] In the following examples and comparative examples, the solid content of natural latex was 60 wt%.

[0027] Example 1

[0028] S1. Dissolve 2 parts of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 60-mesh mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain anhydride-modified mica sheets.

[0029] S2. Mix 30 parts of natural latex, 10 parts of acid anhydride-modified mica flakes, 0.3 parts of benzoyl peroxide and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0030] Example 2

[0031] S1. Dissolve 1 part of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 80-mesh mica sheets at a rate of 3 mL / min. Grind the mixture and dry it at 80 °C to obtain anhydride-modified mica sheets.

[0032] S2. Mix 20 parts of natural latex, 5 parts of acid anhydride-modified mica flakes, 0.1 parts of benzoyl peroxide, and 60 parts of water. While stirring (1500 r / min), add 0.2 parts of magnesium chloride. After the addition is complete, continue stirring for 10 min. Then add 5 parts of OP-10 (25% by mass) and Gemini1231 surfactant to terminate the reaction, and obtain the oil and gas well differential pressure activation and plugging agent.

[0033] Example 3

[0034] S1. Dissolve 3 parts of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 20-mesh mica sheets at a rate of 0.5 mL / min. Grind the mixture and dry it at 75 °C to obtain anhydride-modified mica sheets.

[0035] S2. Mix 40 parts of natural latex, 15 parts of acid anhydride-modified mica flakes, 0.5 parts of benzoyl peroxide, and 80 parts of water. While stirring (1500 r / min), add 2 parts of magnesium sulfate. After the addition is complete, continue stirring for 20 min. Then add 20% OP-40 and 10 parts of Gemini1231 surfactant to terminate the reaction, and obtain the oil and gas well differential pressure activation and plugging agent.

[0036] Example 4

[0037] S1. Dissolve 2 parts of 3,4,5,6-tetrahydrophthalic anhydride in 15 parts of anhydrous ethanol, then add it dropwise to 20 parts of 60-mesh mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain mica sheets modified with anhydride compounds.

[0038] S2. Mix 30 parts of natural latex, 10 parts of acid anhydride-modified mica flakes, 0.3 parts of benzoyl peroxide and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0039] Example 5

[0040] S1. Dissolve 0.5 parts of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 60-mesh mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain modified mica sheets.

[0041] S2. Dissolve 1.5 parts of 3,4,5,6-tetrahydrophthalic anhydride in 15 parts of anhydrous ethanol, then add it dropwise to 20 parts of modified mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain anhydride-modified mica sheets.

[0042] S3. Mix 30 parts of natural latex, 10 parts of acid anhydride-modified mica flakes, 0.3 parts of benzoyl peroxide and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0043] Example 6

[0044] S1. Dissolve 1 part of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 60-mesh mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain modified mica sheets.

[0045] S2. Dissolve 1 part of 3,4,5,6-tetrahydrophthalic anhydride in 15 parts of anhydrous ethanol, then add it dropwise to 20 parts of modified mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain anhydride-modified mica sheets.

[0046] S3. Mix 30 parts of natural latex, 10 parts of acid anhydride-modified mica flakes, 0.3 parts of benzoyl peroxide and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0047] Example 7

[0048] S1. Dissolve 1.5 parts of 2,3-diphenylmaleic anhydride in 15 parts of N,N-dimethylformamide, and then add it dropwise to 20 parts of 60-mesh mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain modified mica sheets.

[0049] S2. Dissolve 0.5 parts of 3,4,5,6-tetrahydrophthalic anhydride in 15 parts of anhydrous ethanol, and then add it dropwise to 20 parts of modified mica sheets at a rate of 1.5 mL / min. Grind the mixture and dry it at 70 °C to obtain anhydride-modified mica sheets.

[0050] S3. Mix 30 parts of natural latex, 10 parts of acid anhydride-modified mica flakes, 0.3 parts of benzoyl peroxide and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0051] Comparative Example 1

[0052] Mix 30 parts of natural latex, 10 parts of 60-mesh mica flakes, 0.3 parts of benzoyl peroxide, and 70 parts of water. While stirring (1500 r / min), add 1 part of sodium chloride. After the addition is complete, continue stirring for 15 min and then add 8 parts of Gemini1231 surfactant to terminate the reaction, thus obtaining the oil and gas well differential pressure activation and plugging agent.

[0053] Performance testing:

[0054] (1) Static plugging experiment: The oil and gas well pressure difference activation plugging agents obtained in Examples 1 to 7 and Comparative Example 1 were injected into the high temperature and high pressure filter. The filter paper with a pore size of 10 μm was selected, the temperature was adjusted to 70℃, and the pressure was increased to 12 MPa. The pressure change data were recorded to evaluate the plugging effect of the system.

[0055] The results show that by pressurizing to 12MPa, the differential pressure activation plugging agent for oil and gas wells provided by this invention can complete the liquid-solid conversion and seal the pores in a short time, indicating that the differential pressure activation plugging agent for oil and gas wells can effectively seal 10μm filter paper and form a filter cake on the filter paper.

[0056] The filter cakes obtained in Examples 1-7 and Comparative Example 1 were tested for tensile strength and high-temperature aging resistance (150℃×96h, Type 1 laminar flow air aging chamber) according to the method in GB / T 3512-2014, and the change rate was calculated. The results are recorded in Table 1.

[0057] (2) Dynamic plugging experiment: The oil and gas well pressure difference activation plugging agents obtained in Examples 5-7 and Comparative Example 1 were subjected to dynamic plugging experiments. A simulated tubing thread plugging device was used to form different leakage rates and plugging performance relationships, which are recorded in Table 2.

[0058] Table 1 Tensile strength and high temperature aging resistance

[0059]

[0060] As shown in Table 1, the oil and gas well differential pressure activating and plugging agent provided by this invention has a tensile strength of over 22.0 MPa after curing, and a change rate of over -3.51% after a heat aging test at 150℃ for 96 hours. It exhibits high tensile strength and good high-temperature aging resistance. Furthermore, under certain tensile conditions, it only undergoes elastic deformation and does not experience brittle fracture, demonstrating good flexibility. In addition, the oil and gas well differential pressure activating and plugging agents obtained in Examples 5-7 show an increase in tensile strength after a heat aging test at 150℃ for 96 hours. This is mainly because during the heat treatment process, the acid anhydride compound-modified mica flakes react with the natural latex, and the vulcanizing agent further vulcanizes the natural latex. The two synergistically increase the crosslinking density, thereby further increasing the tensile strength.

[0061] Compared with Comparative Example 1, the oil and gas well differential pressure activation plugging agents obtained in Examples 1-7 have higher tensile strength and high-temperature aging resistance than those in Comparative Example 1, indicating that the use of anhydride compounds to modify mica sheets can improve the tensile strength and high-temperature aging resistance of the oil and gas well differential pressure activation plugging agent after curing.

[0062] Compared with Examples 5-7, Examples 1-3 used 2,3-diphenylmaleic anhydride-modified mica flakes, Example 4 used 3,4,5,6-tetrahydrophthalic anhydride-modified mica flakes, and Examples 5-7 used mica flakes modified with both 2,3-diphenylmaleic anhydride and 3,4,5,6-tetrahydrophthalic anhydride. The oil and gas well differential pressure activation plugging agent obtained in Examples 5-7 had higher tensile strength and high-temperature aging resistance than that in Examples 1-4. This indicates that using 3,4,5,6-tetrahydrophthalic anhydride and 2,3-diphenylmaleic anhydride as anhydride compounds to modify the mica flakes can further improve the strength and high-temperature aging resistance of the differential pressure activation plugging agent after curing.

[0063] Table 2. Leakage sealing effect of differential pressure activation plugging agent on simulated tubing threads in oil and gas wells.

[0064]

[0065] As shown in Table 2, when the leakage rate is 80 mL / min, the differential pressure activation plugging agent for oil and gas wells provided by this invention has a very good plugging effect on tubing threads and can completely seal the leak. However, Comparative Example 1 showed leakage and could not completely seal the leak.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A differential pressure activation plugging agent for oil and gas wells, characterized in that, The raw materials include the following parts by weight: 20-40 parts natural latex, 0.1-0.5 parts vulcanizing agent, 5-15 parts acid anhydride-modified mica sheets, 0.2-2 parts activator, 5-10 parts terminator, and 60-80 parts water. The acid anhydride-modified mica sheets are composed of 3,4,5,6-tetrahydrophthalic anhydride and 2,3-diphenylmaleic anhydride in a mass ratio of 1:3 to 3:

1.

2. The differential pressure activation plugging agent for oil and gas wells according to claim 1, characterized in that, The raw materials for the acid anhydride-modified mica sheets include acid anhydride compounds and mica sheets in a mass ratio of 1 to 3:

20.

3. The differential pressure activation plugging agent for oil and gas wells according to claim 1, characterized in that, The preparation method of the acid anhydride compound modified mica sheet includes the following steps: dissolving the acid anhydride compound in a solvent, adding it dropwise to the mica sheet, grinding, and drying to obtain the acid anhydride compound modified mica sheet.

4. The differential pressure activation and plugging agent for oil and gas wells according to claim 3, characterized in that, The solvent includes one or both of N,N-dimethylformamide and ethanol.

5. The differential pressure activation plugging agent for oil and gas wells according to claim 3, characterized in that, The dropping rate is 0.5~3 mL / min.

6. The differential pressure activation plugging agent for oil and gas wells according to claim 1, characterized in that, The vulcanizing agent is a peroxide.

7. The differential pressure activation plugging agent for oil and gas wells according to claim 1, characterized in that, The activator is an inorganic salt; the terminator is a surfactant.

8. A method for preparing a differential pressure activation plugging agent for oil and gas wells according to any one of claims 1 to 7, characterized in that, Includes the following steps: Natural latex, acid anhydride-modified mica flakes, vulcanizing agent and water are mixed, and an activator is added while stirring. Finally, a terminator is added to obtain an oil and gas well differential pressure activation and plugging agent.

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