A gas storage well plugging device and method

Abstract

This invention discloses a gas storage well plugging device and method, which can effectively fill and seal the annulus of a cemented gas storage well with plugging agent. The device includes an injection system, a downhole annulus, and a pressure guiding system; the injection system includes a high-pressure compressor, a gas storage tank, a plugging agent storage tank, and a plugging agent injection hose; the downhole annulus includes an annular space formed between the inner annular pipe and the outer annular pipe; the pressure guiding system includes a pressure-sensing hose, a pressure-sensing pipeline flow controller, and a surface contamination tank; the high-pressure compressor, gas storage tank, and plugging agent storage tank are each independently installed and each connected to an outlet pipeline, the rear ends of which are all connected to a main pipeline, the rear end of which is connected to the plugging agent injection hose, which extends into the annular space; a pressure-sensing hose also extends into the annular space, and the pressure-sensing hose is connected to the surface contamination tank through a pressure-sensing pipeline, on which a pressure-sensing pipeline flow controller is installed.

Description

Technical Field

[0001] This invention belongs to the field of well completion technology for injection and production wells in oil fields and gas storage facilities. It relates to the technology of plugging and sealing gas storage wells after annular pressure occurs. Specifically, it is a device and method for sealing gas storage wells that can complete plugging and sealing. Background Technology

[0002] With the advancement of gas storage construction, a large number of gas storage wells have been put into operation. However, due to harsh operating conditions such as strong injection and extraction, and frequent pressure cycles, some wells have developed micro-cracks in the cement due to natural cementing quality issues and the alternating injection and extraction processes. This creates seepage channels, resulting in annular pressure. The pressurized annulus, filled with corrosive natural gas, accelerates corrosion of the annular casing and wellhead equipment. Traditional methods involve releasing the annular pressure or using a pump truck for secondary cementing, but these methods have certain drawbacks.

[0003] 1. Although existing pressure relief methods can remove corrosive natural gas from the annulus, long-term pressure relief can lead to further expansion of the seepage channels, increasing the possibility and risk of annular pressurization.

[0004] 2. Since the annulus at all levels has been sealed with cement, there is a lack of circulation channels when performing secondary cementing. The cement cannot reach and seal the actual leakage points, and the effect cannot be guaranteed. Summary of the Invention

[0005] To overcome the shortcomings of existing methods for dealing with pressurized annulus in gas storage wells, which suffer from high risks and poor effectiveness, this invention provides a gas storage well plugging device and method. This device and method can effectively fill and seal the annulus of cemented gas storage wells with plugging agents. The plugging agent can be quickly delivered to the cement contact surface of the annulus under surface conditions, and solidification and sealing can be completed rapidly. This achieves precise plugging of pressurized annulus wells and effectively solves the problem of pressurized annulus in gas storage wells.

[0006] The technical solution adopted by this invention to solve its technical problem is: a gas storage well plugging device, comprising an injection system, a downhole annulus, and a pressure guiding system; wherein, the injection system includes a high-pressure compressor, a gas storage tank, a plugging agent storage tank, and a plugging agent injection hose; the downhole annulus includes an inner annulus pipe, an outer annulus pipe, and the annulus space between the inner and outer annulus pipes; the pressure guiding system includes a pressure-sensing hose, a pressure-sensing pipeline flow controller, and a surface contamination pool; the high-pressure compressor, gas storage tank, and plugging agent storage tank are each independently installed and each connected to an outlet pipeline, the rear ends of the three outlet pipelines are all connected to a main pipeline, the rear end of the main pipeline is connected to the plugging agent injection hose, and the plugging agent injection hose extends into the annulus space; a pressure-sensing hose also extends into the annulus space, the pressure-sensing hose is connected to the surface contamination pool through a pressure-sensing pipeline, and a pressure-sensing pipeline flow controller is installed on the pressure-sensing pipeline.

[0007] As a further embodiment of the present invention, a single-flow valve and a flow control valve are sequentially provided on the main pipeline.

[0008] As a further embodiment of the present invention, the flow control valve is provided with an inlet pressure display.

[0009] As a further embodiment of the present invention, nitrogen is stored in the gas storage tank.

[0010] A method for plugging leaks in a gas storage well, using the aforementioned device, involves opening the corresponding casing gate when the annulus becomes pressurized, allowing the pressure-guiding system to release the pressure in the annulus to standard atmospheric pressure; calculating the remaining usable volume for plugging within the annulus based on the original annulus pressure and gas composition; preparing the plugging agent based on the remaining usable volume; and detecting the annulus fluid level depth H. 检 and the depth value H of the sealant 堵漏剂 When the annular liquid level depth value H 检 ≥ Leakage sealing agent depth value H 堵漏剂 At this time, the bottom ports of the plugging agent injection hose and the pressure-sensing hose are raised to the wellhead to perform overall gas pressurization of the annulus space; when the annulus fluid level depth value H 检 Leak-sealing agent depth value H 堵漏剂 At this time, the pressure-sensing hose is inserted to the bottom of the annular space, and the gas covered by the plugging agent is drawn upwards until the plugging agent appears in the surface contamination pool. Then, the plugging agent is injected into the annular space 8 through the plugging agent storage tank until H 检 ≥H 堵漏剂 Then, the bottom port of the plugging agent injection hose and the pressure-inducing hose is raised to the wellhead to pressurize the annulus space with gas.

[0011] As a further embodiment of the present invention, the calculation of the remaining volume in the annular space that can be used for plugging specifically involves: recording the pressure P1 before depressurization, recording the gas volume Q1 released from the annular space through the pressure tapping pipeline flow controller, and applying the real gas state equation:

[0012] P1V 环空空间体积 =nZRT

[0013] In the formula, P1 is the pressure before the annular space is released, and V 环空空间体积 The volume above the remaining liquid level in the annulus is denoted by , n is the molar mass of the released gas, Z is the compressibility factor corresponding to the current pressure, R is the gas constant, and T is the wellhead temperature when the pressure is released.

[0014] The molar mass n of the released gas is obtained from the released gas volume Q1. Taking the wellhead temperature T at the release pressure as the geothermal isothermal layer temperature of 15℃, the remaining usable volume in the annulus space for plugging is calculated, i.e., the volume V above the remaining liquid level in the annulus space. 环空空间体积。

[0015] As a further embodiment of the present invention, the step of preparing the plugging agent according to the remaining usable volume in the annular space specifically involves setting the volume of the plugging agent to be V above the remaining liquid level in the annular space. 环空空间体积 The amount of sealant should be 1 / 3, and the density of the sealant should be greater than 1.05, the viscosity less than 1cp, and the curing time of the sealant should be greater than 72h.

[0016] As a further embodiment of the present invention, the overall gas pressurization of the annular space specifically involves: transporting the gas from the gas storage tank to the annular space, performing pressure sealing for 72 hours, and then testing the sealing quality.

[0017] As a further embodiment of the present invention, when the pressure-sensing hose is inserted below the surface of the sealing agent, the flow controller of the pressure-sensing pipeline is in the closed state.

[0018] The beneficial effects of this invention include: This invention provides a method and apparatus for effectively filling and sealing the annulus of cemented gas storage wells with plugging agents. It allows for rapid delivery of the plugging agent to the cement contact surface in the annulus under surface conditions, quickly completing solidification and sealing, achieving precise plugging of pressurized annulus wells, and effectively solving the problem of pressurized annulus in gas storage wells. In particular, it is not limited by the volume within the annulus, does not require deep penetration into the wellbore annulus, and does not require significant structural modifications to the valve devices at the wellhead and in the annulus space. It enables secondary cementing of the annular space of gas storage wells while ensuring construction quality, providing an effective solution for managing pressurized annulus in gas storage wells. Attached Figure Description

[0019] To illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of a gas storage well plugging device according to the present invention.

[0021] The following are the labels in the attached diagram: 1. High-pressure compressor; 2. Gas storage tank; 3. Leak-stopping agent storage tank; 4. Check valve; 5. Flow control valve; 6. Inlet pressure indicator; 7. Annular inner pipe; 8. Annular space; 9. Annular outer pipe; 10. Leak-stopping agent injection hose; 11. Pressure tapping hose; 12. Pressure tapping line flow controller; 13. Ground contamination pool. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used only to distinguish components and should not be construed as indicating or implying relative importance.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Example 1

[0026] A gas storage well plugging device consists of three parts: an injection system, a downhole annulus, and a pressure guiding system.

[0027] The injection system includes a high-pressure compressor 1, a gas storage tank 2, a plugging agent storage tank 3, a check valve 4, a flow control valve 5, an inlet pressure display 6, and a plugging agent injection hose 10.

[0028] The downhole annulus includes an inner annulus tube 7, an outer annulus tube 9, and an annulus space 8 between the inner annulus tube 7 and the outer annulus tube 9; the inner annulus tube 7 is an oil casing, etc., and the outer annulus tube 9 is a technical casing, etc.

[0029] The pressure guiding system includes a pressure-guiding hose 11, a pressure-guiding pipeline flow controller 12, and a ground contamination tank 13;

[0030] Based on the above implementation scheme, the high-pressure compressor 1, gas storage tank 2, and plugging agent storage tank 3 are each set up independently and each is connected to an outlet pipeline. The rear ends of the outlet pipelines of the three are all connected to the main pipeline. A check valve 4 and a flow control valve 5 are installed in sequence on the main pipeline. An inlet pressure indicator 6 is installed at the flow control valve 5. The rear end of the main pipeline is connected to the plugging agent injection hose 10, which extends into the annular space 8.

[0031] A pressure-sensing hose 11 extends into the annular space 8. The pressure-sensing hose 11 is connected to the ground pollution pool 13 through a pressure-sensing pipeline. A pressure-sensing pipeline flow controller 12 is installed on the pressure-sensing pipeline.

[0032] The high-pressure compressor 1 is used to increase the low-pressure gas to high pressure; the gas storage tank 2 stores nitrogen gas, which is used to pressurize the annular space 8 through pipelines.

[0033] Example 2

[0034] A method for plugging leaks in a gas storage well, based on a gas storage well plugging device described in Example 1, is illustrated using the plugging of a single annular casing as an example:

[0035] When the annular space 8 is pressurized, the corresponding bushing gate is opened first, and the pressure is released by the pressure guiding system. The pressure P1 before pressure release is recorded, and the gas volume Q1 released from the annular space 8 is recorded by the pressure guiding pipeline flow controller 12. The pressure of the annular space 8 is then released to the standard atmospheric pressure.

[0036] From the real gas law:

[0037] P1V 环空空间体积 =nZRT

[0038] In the formula, P1 is the pressure before the annular space 8 is released, and V 环空空间体积 The volume above the remaining liquid level in the annulus 8 is denoted by , n is the molar mass of the released gas, Z is the compressibility factor corresponding to the current pressure, R is the gas constant, and T is the wellhead temperature when the pressure is released.

[0039] Based on the released gas volume Q1, the molar mass n of the released gas can be determined. Taking the wellhead temperature T at the release pressure as the geothermal isothermal layer temperature of 15℃, the remaining usable volume in the annulus space 8 for plugging can be calculated, i.e., the volume V above the remaining liquid level in the annulus space 8. 环空空间体积 ;

[0040] In the above implementation scheme, an ultrasonic liquid level tester can be connected to the pressure guiding system to verify the liquid level depth H in the annular space. 环空液面深度 This leads to the correction of the volume within the annular space 8, and the relationship between the two is as follows:

[0041] V 环空空间体积=π(D) 外管直径 2 -d 内管直径 2 ) / 4*H 环空液面深度 ;

[0042] Based on the above scheme, it should be noted that: since the released gas is above the annular fluid level, the depth of the annular space 8 can be determined by the released gas, facilitating the fabrication of the length of the pressure-injecting hose 11 extending into the annular space 8. There is a portion of sparse formation water within the annular space 8, which needs to be pumped away through the pressure-injecting hose 11 to ensure that the plugging agent can make contact as much as possible below the fluid level in the annular space 8, forming a good bond with the cement and completing the well sealing.

[0043] Furthermore, based on the volume V above the remaining liquid level in the annular space 8 环空空间体积 Prepare the sealant. Specifically, set the sealant volume to V. 环空空间体积 The amount of sealant should be 1 / 3, and the density of the sealant should be greater than 1.05 and the viscosity less than 1 cp. This ensures that the sealant flows naturally to the low-lying area within the annular space 8. The curing time of the sealant should be controlled to be greater than 72 hours.

[0044] Detecting the depth value H of the annular liquid level 检 and the depth value H of the sealant 堵漏剂 When the annular liquid level depth value H 检 ≥ Leakage sealing agent depth value H 堵漏剂 When the plugging agent is distributed to the bottom of the annular space 8, the entire injection system and pressure guiding system are lifted to the vicinity of the wellhead. Even if the bottom ports of the plugging agent injection hose 10 and the pressure guiding hose 11 are located at the wellhead, the entire gas is pressurized, that is, the gas in the gas storage tank 2 is transported to the annular space 8. After 72 hours of pressurized plugging, the plugging quality is checked.

[0045] In the above implementation scheme, nitrogen is injected into the annular space 8, which is equivalent to applying downward pressure to the plugging agent. This is because when the plugging agent seals certain leaks, the space above it is essentially without atmospheric pressure, while the pressure from the formation rising through the annular space 8 is relatively high. Therefore, nitrogen needs to be injected to balance the pressure and ensure that the plugging agent can maintain a stable annular state, so that the plugging agent can form a complete junction with the annular space 8.

[0046] When the depth of the annular liquid level is H 检 Leak-sealing agent depth value H 堵漏剂 If the leak-sealing agent is not evenly distributed to the bottom of the annular space 8, then the pressure-guiding hose 11 of the pressure guiding system is inserted into the bottom of the annular space 8, and the gas covered by the leak-sealing agent is drawn upwards until the leak-sealing agent appears in the ground contamination pool 13. Then, a portion of the leak-sealing agent is repeatedly injected into the annular space 8 through the leak-sealing agent storage tank 3 until H 检 ≥H堵漏剂 This means that the plugging agent is distributed to the bottom of the annular space 8. At this time, the entire injection system and pressure guiding system are raised to the vicinity of the wellhead. Even if the bottom ports of the plugging agent injection hose 10 and the pressure guiding hose 11 are located at the wellhead, the whole gas is pressurized, that is, the gas in the gas storage tank 2 is transported to the annular space 8. After 72 hours of pressurized plugging, the plugging quality is checked.

[0047] In the above implementation scheme, it should be noted that when the pressure-sensing hose 11 is inserted below the surface of the plugging agent, the flow controller 12 of the pressure-sensing pipeline should be in the closed state to ensure that there is a balanced back pressure in the annular space 8, and to prevent the plugging agent from flowing into the pressure-sensing hose 11 in advance, which would affect the liquid level judgment.

[0048] The plugging agent injection hose 10 and pressure tapping hose 11 after the wellhead are removed should be flushed and replaced in a timely manner to prevent the plugging agent from damaging the pipeline.

[0049] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention. Furthermore, the shapes and proportions of the components in the figures are merely illustrative and intended to aid in understanding the invention; they are not intended to specifically limit the shapes and proportions of the components of the invention and should not be construed as limiting the invention in any way.

Claims

1. A method for plugging leaks in a gas storage well, characterized in that, A gas storage well plugging device with the following structure is used: including an injection system, a downhole annulus, and a pressure guiding system; wherein, the injection system includes a high-pressure compressor (1), a gas storage tank (2), a plugging agent storage tank (3), and a plugging agent injection hose (10); the downhole annulus includes an inner annulus pipe (7), an outer annulus pipe (9), and an annulus space (8) between the inner annulus pipe (7) and the outer annulus pipe (9); the pressure guiding system includes a pressure-sensing hose (11), a pressure-sensing pipeline flow controller (12), and a surface contamination tank (13); The high-pressure compressor (1), gas storage tank (2), and plugging agent storage tank (3) are set up independently and each is connected to an outlet pipeline. The rear end of the outlet pipelines of the three are connected to the main pipeline. The rear end of the main pipeline is connected to the plugging agent injection hose (10). The plugging agent injection hose (10) extends into the annular space (8). A pressure-sensing hose (11) also extends into the annular space (8). The pressure-sensing hose (11) is connected to the ground pollution pool (13) through the pressure-sensing pipeline. A pressure-sensing pipeline flow controller (12) is provided on the pressure-sensing pipeline. The gas storage well plugging method is as follows: When the annulus (8) is pressurized, the corresponding casing gate is opened, and the pressure is released by the pressure guiding system to reduce the pressure of the annulus (8) to standard atmospheric pressure; the remaining volume of the annulus (8) available for plugging is calculated based on the original annulus pressure value and gas composition, and the plugging agent is prepared based on the remaining volume of the annulus (8) available for plugging; the annulus liquid level depth value H is detected. 检 and the depth value H of the sealant 堵漏剂 When the annular liquid level depth value H 检 ≥ Leakage sealing agent depth value H 堵漏剂 When the plugging agent is evenly distributed to the bottom of the annular space (8), the bottom ports of the plugging agent injection hose (10) and the pressure-inducing hose (11) are raised to the wellhead to perform overall gas pressurization on the annular space (8); when the annular fluid level depth value H 检 Leak-sealing agent depth value H 堵漏剂 If the leak-sealing agent is not evenly distributed to the bottom of the annular space (8), insert the pressure-sensing hose (11) into the bottom of the annular space (8) and pump the gas covered by the leak-sealing agent upwards until the leak-sealing agent appears in the ground contamination pool (13). Then inject the leak-sealing agent into the annular space (8) through the leak-sealing agent storage tank (3) until H 检 ≥H 堵漏剂 Then, the bottom port of the plugging agent injection hose (10) and the pressure-inducing hose (11) is raised to the wellhead to pressurize the annulus space (8) with gas. There is some sparse formation water in the annular space (8). Some of the formation water needs to be pumped away through the pressure-inducing hose (11) to ensure that the plugging agent can contact the liquid surface in the annular space (8) as much as possible, form a good bond with the cement, and complete the sealing of the well.

2. The method for plugging leaks in a gas storage well according to claim 1, characterized in that, A single-flow valve (4) and a flow control valve (5) are installed sequentially on the main pipeline.

3. The method for plugging leaks in a gas storage well according to claim 2, characterized in that, An inlet pressure display (6) is provided at the flow control valve (5).

4. The method for plugging leaks in a gas storage well according to claim 2, characterized in that, Nitrogen is stored in the gas storage tank (2).

5. The method for plugging leaks in a gas storage well according to claim 1, characterized in that, The calculation of the remaining usable volume in the annular space (8) for plugging is specifically as follows: record the pressure P1 before depressurization, and record the gas volume Q1 released from the annular space (8) through the pressure tapping pipeline flow controller (12), based on the real gas state equation: P1V 环空空间体积 =nZRT In the formula, P1 is the pressure in the annular space (8) before depressurization, and V 环空空间体积 The volume above the remaining liquid level in the annular space (8) is n, the molar mass of the released gas is Z, the compressibility factor corresponding to the current pressure is R, the gas constant is T, and the wellhead temperature is T when the pressure is released. The molar mass n of the released gas is obtained from the released gas volume Q1. Taking the wellhead temperature T at the release pressure as the geothermal constant layer temperature of 15℃, the remaining volume in the annular space (8) that can be used for plugging is calculated, that is, the volume V above the remaining liquid surface in the annular space (8). 环空空间体积。 6. The method for plugging leaks in a gas storage well according to claim 1, characterized in that, The process of preparing the plugging agent based on the remaining usable volume in the annular space (8) specifically involves setting the volume of the plugging agent to be V above the remaining liquid level in the annular space (8). 环空空间体积 The amount of sealant should be 1 / 3, and the density of the sealant should be greater than 1.05, the viscosity less than 1cp, and the curing time of the sealant should be greater than 72h.

7. A method for plugging leaks in a gas storage well according to claim 1, characterized in that, The process of pressurizing the annular space (8) involves: transporting the gas from the gas storage tank (2) to the annular space (8), performing pressure sealing for 72 hours, and then testing the sealing quality.

8. The method for plugging leaks in a gas storage well according to claim 1, characterized in that, When the pressure-sensing hose (11) is submerged below the surface of the sealing agent, the pressure-sensing line flow controller (12) is in the off state.

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