Leakage point pressure difference response high-strength blocking agent based on iron ion dynamic cross-linked latex and preparation method of leakage point pressure difference response high-strength blocking agent

Abstract

The invention provides a leakage point pressure difference response high-strength blocking agent based on iron ion dynamic cross-linked latex and a preparation method thereof, and the raw materials comprise the following components in parts: 60-120 parts of latex, 60-120 parts of deionized water, 5-15 parts of an activator, 5-10 parts of a defoamer, 100 parts of a terminator, 100 parts of a stabilizer, 10 parts of a 20% ferric chloride solution, and the balance of water. Rubber particles are dynamically crosslinked through ferric ions, and the plugging strength is remarkably improved. Compared with a traditional differential pressure plugging agent, the plugging strength for small holes with the diameter of 0.5 mm reaches 35.67 MPa and is improved by about 238%, and the plugging strength for large holes with the diameter of 1 mm reaches 9.68 MPa and is improved by about 428%. And the plugging device is suitable for plugging conditions with higher leakage point pressure difference. In addition, the plugging agent can realize rapid and high-strength plugging of an underground pipe column, and provides a more efficient and more reliable solution for well site construction.

Description

Technical Field

[0001] The present invention belongs to the field of sealing leakage in oil and gas systems, and more specifically, relates to a high-strength leak point differential pressure response plugging agent and a preparation method thereof, which are mainly used for quickly plugging micro-fracture leakage of downhole strings. Background Art

[0002] About 10% of the in-service wells in offshore oil and gas fields in China have wellbore integrity problems, mainly due to reasons such as dynamic / static seal failure and cement sheath damage. Among them, 42% of the wellbore integrity problems are manifested as annulus pressure caused by seal damage, and 20% of the annulus pressure wells are high-risk wells, with serious potential accident hazards, posing a major threat to safe production.

[0003] Currently, the repair technologies for annulus pressure problems mainly include traditional mechanical repair and injection repair. However, these technologies generally have problems such as complex construction, long operation cycle, high cost, high risk, low success rate of migration, and difficulty in completely eliminating subsequent impacts, and it is difficult to meet the requirements of quickly and safely eliminating annulus pressure in offshore oil and gas wells.

[0004] With the increasing prominence of annulus pressure problems in production wells of offshore oil and gas fields, it is urgent to develop a differential pressure plugging agent suitable for quickly plugging leaks in downhole strings based on the characteristics of seal damage in production wells, and establish a technical system suitable for rapid repair of seals in offshore oil and gas wells in China. The establishment of this technical system can not only provide technical support for workover operations, safe production, and wellbore integrity management, but also has important strategic significance for breaking through existing technical barriers and ensuring the safety of China's oil and gas resources. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a high-strength plugging agent with leak point differential pressure response based on iron ion dynamic cross-linked latex.

[0006] The present invention is achieved through the following technical solutions:

[0007] A high-strength plugging agent with leak point differential pressure response based on iron ion dynamic cross-linked latex, calculated by parts, includes the following components: 60 - 120 parts of latex, 60 - 120 parts of deionized water, 5 - 15 parts of activator, 5 - 10 parts of defoamer, 100 parts of terminator, 100 parts of stabilizer, 10 parts of 20% ferric chloride solution, and the balance is water.

[0008] Specifically, a high-strength plugging agent with leakage point differential pressure response based on iron ion dynamically cross-linked latex is prepared in the following manner: In the first step, latex and deionized water are stirred evenly to form a latex dilution solution; in the second step, the stirrer speed is controlled at 500 - 2000 r / min at 40 - 80 °C, the activator is dropped into the flask, an antifoaming agent is added, and then stirring is stopped for 20 min to obtain an emulsion with micron-scale to millimeter-scale particles; in the third step, stirring is started, and a terminator and a stabilizer are added; in the fourth step, after stirring for 15 min, a 20% ferric chloride solution is added to prepare a high-strength plugging agent with leakage point differential pressure response based on iron ion dynamically cross-linked latex.

[0009] Specifically, the latex includes chloroprene latex, silicone rubber latex, ethylene propylene diene monomer (EPDM) latex, nitrile latex, natural latex, butyl latex, etc.

[0010] Specifically, the activator is an inorganic salt solution, such as sodium chloride, magnesium chloride, copper chloride, etc.

[0011] Specifically, the antifoaming agent is a silicone antifoaming agent.

[0012] Specifically, the terminator is a surfactant, such as anionic, cationic, and non-ionic surfactants.

[0013] Specifically, the stabilizer is a polymeric surfactant.

[0014] The beneficial effects of the present invention compared with the prior art are as follows:

[0015] (1) The leakage point differential pressure response plugging agent provided by the present invention only plugs the leakage points with pressure difference in the pipe string, maintains a normal flowing state during normal flow and storage, and after sealing, the excess differential pressure plugging agent colloid can be returned to the ground. While playing a plugging role, it avoids blocking or damaging the precision devices underground.

[0016] (2) The leakage point differential pressure response plugging agent provided by the present invention has the advantages of fast plugging speed, convenient construction, low cost, and high plugging strength. Trivalent iron ions make the surface of rubber particles dynamically cross-linked, further enhancing the plugging strength of the whole system. Description of the Drawings

[0017] Figure 1 On the left is the leakage point differential pressure response plugging agent prepared in Example 1 of the present invention, and on the right is the high-strength leakage point differential pressure response plugging agent based on iron ion dynamically cross-linked latex prepared in Example 2.

[0018] Figure 2 a is the particle size spectrum measured by a laser particle size analyzer of the leakage point differential pressure response plugging agent prepared in Example 1 of the present invention. Figure 2b is the particle size distribution map measured by a laser particle size analyzer of the high-strength plugging agent with leakage point differential pressure response based on iron ion dynamic cross-linked latex prepared in Example 2.

[0019] Figure 3 a is the scanning electron micrograph of the plugging agent with leakage point differential pressure response prepared in Example 1 of the present invention. Figure 3 b is the scanning electron micrograph of the high-strength plugging agent with leakage point differential pressure response based on iron ion dynamic cross-linked latex prepared in Example 2.

[0020] Figure 4 a is the plugging strength test curve of the plugging agent with leakage point differential pressure response prepared in Example 1 and Example 2 of the present invention for a small hole with a diameter of 0.5 mm. Figure 4 b is the plugging strength test curve of the plugging agent with leakage point differential pressure response prepared in Example 1 and Example 2 of the present invention for a small hole with a diameter of 1 mm. Detailed implementation manners

[0021] The present invention will be further described below in conjunction with embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0022] Example 1:

[0023] In this example, 90 parts of carboxylated nitrile latex and 90 parts of deionized water were stirred evenly to form a latex dilution solution; at 80 °C, the stirrer speed was controlled at 800 r / min, 10 parts of 20% magnesium chloride activator was dropped into the flask, 10 parts of defoamer was added, and then stirring was stopped for 20 min to obtain an emulsion with micron-sized particles; stirring was started, 100 parts of 20% OP-10 emulsifier and 100 parts of 0.6% xanthan gum solution were added. After stirring for 15 min, a plugging agent with leakage point differential pressure response was prepared. The product schematic diagram is as shown Figure 1 on the left.

[0024] Example 2:

[0025] In this example, 90 parts of carboxylated nitrile latex and 90 parts of deionized water were stirred evenly to form a latex dilution solution; at 80 °C, the stirrer speed was controlled at 800 r / min, 10 parts of 20% magnesium chloride activator was dropped into the flask, 10 parts of defoamer was added, and then stirring was stopped for 20 min to obtain an emulsion with micron-sized particles; stirring was started, 100 parts of 20% OP-10 emulsifier and 100 parts of 0.6% xanthan gum solution were added. After stirring for 15 min, 10 parts of 20% iron chloride solution by mass concentration was added to prepare a high-strength plugging agent with leakage point differential pressure response based on iron ion dynamic cross-linked latex. The product schematic diagram is as shown Figure 1 on the right.

[0026] Example 3:

[0027] Material characterization studies were carried out on the leakage point differential pressure response plugging agents prepared in Example 1 and Example 2. The specific tests included systematic evaluation using a laser particle size analyzer (DLS) and a scanning electron microscope (SEM).

[0028] The laser particle size analyzer analysis gave the particle size distribution of the prepared leakage point differential pressure response plugging agent as Figure 2 shown in Figure 2 a is the particle size distribution of the sample in Example 1, with an average particle size of 4.348 μm and a peak at 0.448 μm; Figure 2 b is the particle size distribution of the iron ion dynamic cross-linking modified plugging agent sample prepared in Example 2, with an average particle size of 46.241 μm and a peak at 8.934 μm.

[0029] The observation results of the scanning electron microscope (SEM)( Figure 3 ) revealed significant structural differences: Figure 3 As shown in a, the sample in Example 1 had a loose large particle accumulation structure in its microscopic morphology because the Fe3+ cross-linking system was not introduced; while the iron ion dynamic cross-linking modified plugging agent prepared in Example 2( Figure 3 b) showed a dense three-dimensional network structure, with a large number of filamentous cross-linking bodies on the surface. This structural feature was directly related to the formation of dynamic cross-linking bonds. A coarser and denser polymer network would greatly improve the mechanical properties of the material.

[0030] Example 4:

[0031] The plugging situation of microcracks in downhole pipe strings was simulated in the laboratory. Using a syringe-type simulation device and an electronic universal material testing machine, the plugging strength of the leakage point differential pressure response plugging agents prepared in Examples 1 and 2 was tested at room temperature for pores with a diameter of 1 mm. The hydraulic press drove the push rod to press down at a rate of 10 mm / min, pushing the plugging agent colloid to plug the bottom 0.5 mm or 1 mm pores, and finally breaking through the ultimate bearing pressure under the increasing pressure. The area where the push rod was connected to the liquid surface was about 0.785 cm 2 .

[0032] The plugging strength was calculated from the pressure-displacement curve measured by the electronic universal material testing machine, as Figure 4 shown. The abscissa is the stroke of the hydraulic press pressing down, and the ordinate is the pressure applied to the plugging liquid.

[0033] From Figure 4It can be seen from a that the maximum pressure-bearing capacity of the leak point differential pressure response plugging agent prepared in Example 1 is 14.97 MPa when sealing a small hole with a diameter of 0.5 mm, and the maximum pressure-bearing capacity of the leak point differential pressure response high-strength plugging agent based on iron ion dynamic cross-linked latex prepared in Example 2 is 35.67 MPa. The overall plugging strength is increased by about 238% compared with the plugging agent without iron ion dynamic cross-linking.

[0034] It can be seen from Figure 4 b that the maximum pressure-bearing capacity of the leak point differential pressure response plugging agent prepared in Example 1 is 2.26 MPa when sealing a large hole with a diameter of 1 mm, and the maximum pressure-bearing capacity of the leak point differential pressure response high-strength plugging agent based on iron ion dynamic cross-linked latex prepared in Example 2 is 9.68 MPa. The overall plugging strength is increased by about 428% compared with the plugging agent without iron ion dynamic cross-linking.

[0035] In addition, the traveling speed of the hydraulic press is 0.16 mm / s, which means that the leak point differential pressure response plugging agent can achieve plugging under a relatively small differential pressure.

[0036] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A high-strength plugging agent with differential pressure response at leakage points based on iron ion dynamically cross-linked latex, characterized in that, The raw materials are calculated by parts and include the following components: 60 - 120 parts of latex, 60 - 120 parts of deionized water, 5 - 15 parts of activator, 5 - 10 parts of defoamer, 100 parts of terminator, 100 parts of stabilizer, 10 parts of 20% ferric chloride solution, and the balance is water.

2. The high-strength plugging agent with leakage point differential pressure response based on iron ion dynamic cross-linked latex according to claim 1, characterized in that The plugging agent is prepared in the following manner: First step, latex and deionized water are stirred evenly to form a latex dilution solution; Second step, at 40 - 80 °C, the stirrer speed is controlled at 500 - 2000 r / min, the activator is added dropwise to the flask, the defoamer is added, and then stirring is stopped for 20 min to obtain an emulsion with micron - millimeter - sized particles; Third step, stirring is started, and the terminator and stabilizer are added; Fourth step, after stirring for 15 min, 20% ferric chloride solution is added to prepare a high - strength plugging agent with a leak - point differential pressure response based on iron - ion dynamic cross - linked latex.

3. A high-strength plugging agent with differential pressure response to leakage points based on iron ion dynamically crosslinked latex according to claim 1, characterized in that, The latex includes chloroprene latex, silicone rubber latex, ethylene - propylene - diene monomer (EPDM) latex, nitrile latex, natural latex, butyl latex, etc.

4. A high-strength plugging agent with differential pressure response at leakage points based on iron ion dynamically crosslinked latex according to claim 1, characterized in that, The activator is an inorganic salt solution, such as sodium chloride, magnesium chloride, copper chloride, etc.

5. A high-strength plugging agent with differential pressure response at leakage points based on iron ion dynamically crosslinked latex according to claim 1, characterized in that The defoamer is a silicone defoamer.

6. The high-strength plugging agent with leakage point differential pressure response based on iron ion dynamically crosslinked latex according to claim 1, wherein The terminator is a surfactant, such as anionic, cationic, and non - ionic surfactants.

7. The high-strength plugging agent with differential pressure response at leakage point based on iron ion dynamic cross-linked latex according to claim 1, characterized in that The stabilizer is a polymer - type surfactant.

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