Gas field immovable string continuous well plugging method

Abstract

The invention discloses a gas field immovable tubular column continuous well sealing method which comprises the following steps: putting a fishable sealing bridge plug at the upper part of a tool string in a multi-sealing tubular column oil pipe, and performing pressure test at a wellhead after the bridge plug is set; after the pressure test is qualified, the fishable bridge plug in the well is fished out, and the shaft is circularly cleaned; putting a permanent bridge plug at the upper part of the tool string in the oil pipe and setting, opening a gas well casing gate, and injecting cement into a gas well oil jacket annulus from the casing gate after emptying to block a gas well stratum and the annulus; cement is injected into the in-well oil pipe from the gas well oil pipe gate to block the oil pipe; according to the method, the problem that in the well plugging process of a multi-sealing production pipe column, pulling-out is difficult is solved, construction is easy, the construction period is short, and the simple, safe, effective and reliable plugging effect of an old well with a complex production pipe column of the gas well can be achieved.

Description

Technical Field

[0001] This invention patent relates to the field of natural gas well workover engineering technology, specifically to a method for continuous well sealing without moving the tubing string in a gas field. Background Technology

[0002] The gas field has a large number of abandoned gas wells in the later stages of development. Currently, well sealing first requires addressing the wellbore to ensure its unobstructed flow, then employing a segmented sealing method to plug the old wells. However, many gas wells utilize integrated fracturing and completion tubing, which includes downhole tools such as hydraulic anchors and packers. Based on field operations, when multiple hydraulic anchors and packers are present in the production tubing, retrieving the tubing is difficult due to packer release issues and hydraulic anchor jamming. For these multi-packer tubing strings, the tubing is cut above the safety sub or hydraulic anchor to retrieve the remaining tubing from the well. For some wells, milling operations are required, resulting in long wellbore treatment cycles and high costs, impacting well sealing. Summary of the Invention

[0003] The purpose of this invention is to provide a method for continuous well sealing without moving the tubing string in gas fields. This method can solve the problem of difficulty in tripping and sealing the well using integrated fracturing and production tubing in gas wells.

[0004] The technical solution adopted in this invention is continuous well sealing without moving the tubing string in a gas field, including the following steps: Step 1: Identify the target gas well; Step 2: Insert a retrieveable bridge plug or a pressure-balanced bridge plug into the gas well. Step 3: Pressure test the tubing above the retrievable bridge plug or pressure-balanced bridge plug. Step 4: Retrieve the salvageable bridge plug or the pressure-balanced bridge plug; Step 5: Clean the well casing; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well producing layer and wellbore.

[0005] The invention is further characterized by: Step 1 specifically includes: Step 11: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12: Select old gas field wells with two or more packers in the production tubing from the initial target gas field wells as the final target gas field wells to be plugged.

[0006] Step 2 specifically includes: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it.

[0007] Step 3 specifically includes: using a portable pressure testing pump to test the oil pipe above the retrievable bridge plug at a pressure of 15-25 MPa.

[0008] Step 4 involves lowering a special retrieval tool for the retrieval bridge plug into the upper part of the retrieval bridge plug via an oil pipe or cable to retrieve it.

[0009] Step 5 involves circulating the wellbore cleaning agent through the tubing and using a positive circulation well washing method to clean the tubing and casing.

[0010] Step 6 specifically includes: Step 61: Place the permanent bridge plug in the upper part of the tool string inside the tubing, and use a cable or tubing to lower the permanent bridge plug setting tool and set the permanent bridge plug. Step 62: Use a portable pressure testing pump to test the wellhead tubing at a pressure of 15 MPa. After stabilizing the pressure for 30 minutes, ensure that the pressure drop is no more than 0.5 MPa.

[0011] Step 7 specifically includes: Step 71: Cement is squeezed into the annulus of the gas well through the gas well casing gate to seal the annulus and formation. Step 72: Conduct cementing quality testing on the sealed gas well from inside the tubing. For well sections where the sealing quality does not meet the sealing requirements, inject cement by drilling holes in the tubing. Step 73: Inject cement from the tubing to the wellhead to achieve cement sealing of the entire well section of the multi-sealing tubing string.

[0012] The beneficial effects of this invention are: This invention solves the problem of difficulty in tripping out of the well during the sealing process when multiple production tubing strings are sealed. The method is simple to implement and has a short construction period. It can achieve simple, safe, effective and reliable sealing of old wells with complex production tubing strings. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the multi-sealing pipe string completion structure of the gas well to be sealed by the present invention; Figure 2 This is a schematic diagram of the retrievable bridge plug setting method in the tubing according to the present invention; Figure 3 This is a schematic diagram of the circulating well washing method of the present invention; Figure 4 This is a schematic diagram of the permanent bridge plug setting in the tubing according to the present invention; Figure 5 This is a schematic diagram of the complete wellbore sealing process according to the present invention.

[0014] In the diagram, 1. Surface casing, 2. Tubing, 3. Safety joint, 4. Hydraulic anchor, 5. Packer, 6. Sliding sleeve blasting device, 7. Ball seat, 8. Production layer, 9. Artificial bottom hole, 10. Gas layer casing, 11. Retrievable bridge plug, 12. Wellbore cleaning agent, 13. Permanent bridge plug, 14. Cement. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] This invention provides a method for continuous well sealing in gas fields with a stationary tubing string, used for sealing such... Figure 1 The gas well shown has a surface casing 1, inside which are tubing 2 and a tool string. The tool string includes a safety connector 3, a hydraulic anchor 4, a packer 5, and a sliding sleeve blasting device 6. The bottom of the first tubing near the wellhead is connected to the tool string consisting of the safety connector 3, hydraulic anchor 4, and packer 5 in sequence. The end of this tool string away from the first tubing is connected to the second tubing, which in turn is connected to the packer 5. The end of the packer 5 away from the second tubing is connected to the third tubing, which in turn is connected to the tool string consisting of the sliding sleeve blasting device 6, hydraulic anchor 4, and packer 5. The end of this tool string away from the third tubing is connected to the fourth tubing, and the bottom of the fourth tubing is connected to a ball seat 7. The safety connector 3 is positioned above the packer and hydraulic anchor. This arrangement is to allow for the safe removal of the upper tubing string from the wellhead by disconnecting the safety connector in the event of a downhole tool failure (such as stuck pipe). The hydraulic anchor 4 uses pressure buildup within the tubing to extend the anchor claws outward under hydraulic pressure, allowing them to fit against the inner wall of the casing. This fixes the downhole tubing position during fracturing operations and prevents axial movement. The packer 5 seals the annular space between the tubing and casing, enabling layered fracturing and water injection operations. The sliding sleeve blasting nozzle 6, used in multi-layer fracturing operations, controls the flow of fracturing fluid, ensuring it accurately enters the desired fracturing zone and allows for selective fracturing of different formations. The ball seat 7 receives inserted spheres, such as blasting balls.

[0017] The well sealing method for the above-mentioned gas wells includes the following steps: Step 1: Identify the target gas well; Step 2: Insert a retrieval-type bridge plug or a pressure-balanced bridge plug into the gas well. Step 3: Pressure test the tubing above the retrievable bridge plug or pressure-balanced bridge plug. Step 4: Retrieve the salvageable bridge plug or the pressure-balanced bridge plug; Step 5: Circulate and clean the wellbore; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore; Example 1: A method for continuous well sealing without changing the tubing string in a gas field, specifically including the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2: Insert a pressure-balanced bridge plug into the gas well; Step 3: Pressure test the oil pipe above the pressure-balanced bridge plug; Step 4: Retrieve the pressure-balanced bridge plug; Step 5: Circulate and clean the wellbore; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0018] Example 2, a method for continuous well sealing without moving the tubing string in a gas field, specifically includes the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it. Step 3: Pressure test the oil pipe above the retrievable bridge plug; Step 4: Retrieve the salvageable bridge plug; Step 5: Circulate and clean the wellbore; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0019] Example 3: A method for continuous well sealing without moving the tubing string in a gas field, specifically including the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Lower the retrievable tubing bridge plug 11 to the predetermined position using tubing or cable, and set it. Figure 2 As shown; Step 3: Pressure test the tubing above the retrievable bridge plug. Specifically, this includes using a portable pressure testing pump to test the tubing at the wellhead. For gas wells with a long production time, the pressure test is 15 MPa; for gas wells with a short production time and good tubing performance, the pressure test is 20 MPa-25 MPa. Step 4: Retrieve the salvageable bridge plug; Step 5: Circulate and clean the wellbore; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0020] Example 4: A method for continuous well sealing without moving the tubing string in a gas field, specifically including the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it. Step 3: Pressure test the tubing above the retrievable bridge plug. Specifically, this includes pressure testing the tubing at the wellhead using a portable pressure testing pump. For gas wells with a long production time, the pressure test is 15 MPa; for gas wells with a short production time and good tubing performance, the pressure test is 20 MPa-25 MPa. Step 4: Retrieve the retrieval plug. Specifically, use an oil pipe or cable to lower a special retrieval tool for the retrieval plug to the top of the retrieval plug and retrieve it. Step 5: Circulate and clean the wellbore; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0021] Example 5: A method for continuous well sealing without moving the tubing string in a gas field, specifically including the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it. Step 3: Pressure test the tubing above the retrievable bridge plug. Specifically, this includes pressure testing the tubing at the wellhead using a portable pressure testing pump. For gas wells with a long production time, the pressure test is 15 MPa; for gas wells with a short production time and good tubing performance, the pressure test is 20 MPa-25 MPa. Step 4: Retrieve the retrieval plug. Specifically, use an oil pipe or cable to lower a special retrieval tool for the retrieval plug to the top of the retrieval plug and retrieve it. Step 5: Circulate and clean the wellbore. Specifically, inject wellbore cleaning agent 12 through the tubing using a forward circulation well-washing method to clean the tubing and casing. Figure 3 As shown; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0022] Example 6: A method for continuous well sealing without moving the tubing string in a gas field, specifically including the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it. Step 3: Pressure test the tubing above the retrievable bridge plug. Specifically, this includes pressure testing the tubing at the wellhead using a portable pressure testing pump. For gas wells with a long production time, the pressure test is 15 MPa; for gas wells with a short production time and good tubing performance, the pressure test is 20 MPa-25 MPa. Step 4: Retrieve the retrieval plug. Specifically, use an oil pipe or cable to lower a special retrieval tool for the retrieval plug to the top of the retrieval plug and retrieve it. Step 5: Wellbore circulation cleaning, specifically, wellbore cleaning agent is circulated and injected from the tubing, using a positive circulation well washing method to clean the tubing and casing; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test, specifically including: Step 61: Place the permanent bridge plug 13 into the upper part of the tool string inside the tubing, and use a cable or tubing and a permanent bridge plug setting tool to set the permanent bridge plug 13, such as... Figure 4 As shown; Step 62: Use a portable pressure testing pump to test the pressure at the wellhead tubing. Test the permanent bridge plug at 15 MPa and stabilize the pressure for 30 minutes. The pressure drop should not exceed 0.5 MPa. Step 7: Directly inject cement to seal the gas well production layer and wellbore.

[0023] Example 7, a method for continuous well sealing without moving the tubing string in a gas field, specifically includes the following steps: Step 1: Identify old wells in the target gas field, specifically including: Step 11, Preliminary screening: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12, final screening: Select old gas field wells with two or more packers in the production tubing as the target old gas field wells to be finally plugged; Step 2 involves inserting a retrieveable bridge plug into the gas well, specifically including the following steps: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it. Step 3: Pressure test the tubing above the retrievable bridge plug. Specifically, this includes pressure testing the tubing at the wellhead using a portable pressure testing pump. For gas wells with a long production time, the pressure test is 15 MPa; for gas wells with a short production time and good tubing performance, the pressure test is 20 MPa-25 MPa. Step 4: Retrieve the retrieval plug. Specifically, use an oil pipe or cable to lower a special retrieval tool for the retrieval plug to the top of the retrieval plug and retrieve it. Step 5: Wellbore circulation cleaning, specifically, wellbore cleaning agent is circulated and injected from the tubing, using a positive circulation well washing method to clean the tubing and casing; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test, specifically including: Step 61: Place the permanent bridge plug 13 into the upper part of the tool string inside the tubing, and use a cable or tubing and a permanent bridge plug setting tool to set the permanent bridge plug 13, such as... Figure 4 As shown; Step 62: Use a portable pressure testing pump to test the pressure at the wellhead tubing. Test the permanent bridge plug at 15 MPa and stabilize the pressure for 30 minutes. The pressure drop should not exceed 0.5 MPa. Step 7: Directly inject cement 14 to seal the gas well production layer and wellbore, specifically including: Step 71: Cement is squeezed into the annulus of the gas well through the gas well casing gate to seal the annulus and formation. Step 72: Conduct cementing quality testing on the sealed gas well from inside the tubing. For well sections where the sealing quality does not meet the sealing requirements, cement can be injected by drilling through the tubing. Step 73: Inject cement from the tubing to the wellhead to achieve cement sealing of the entire well section of the multi-sealing tubing string, such as... Figure 5 As shown.

[0024] This invention provides a method for continuous well sealing with a stationary tubing string in gas fields. A retrieveable sealing bridge plug is placed on the upper part of the tool string inside the tubing of a multi-string sealing system. After the bridge plug is set, a pressure test is performed at the wellhead. If the pressure test is successful, the retrieveable bridge plug is retrieved from the well, and the wellbore is circulated and cleaned. A permanent bridge plug is placed on the upper part of the tool string inside the tubing and set. The gas well casing gate valve is opened, and after venting, cement is injected into the gas well casing and annulus through the casing gate valve to seal the gas well formation and annulus. Cement is then injected into the tubing inside the well through the tubing gate valve to seal the tubing. This completes the continuous well sealing with a stationary tubing string in the gas well.

Claims

1. Continuous well sealing with the tubing string stationary in a gas field, characterized in that: Includes the following steps: Step 1: Identify the target gas well; Step 2: Insert a retrieveable bridge plug or a pressure-balanced bridge plug into the gas well. Step 3: Pressure test the tubing above the retrievable bridge plug or pressure-balanced bridge plug. Step 4: Retrieve the salvageable bridge plug or the pressure-balanced bridge plug; Step 5: Clean the well casing; Step 6: Deploy a permanent bridge plug on the upper part of the gas well production tubing tool string and perform a pressure test; Step 7: Directly inject cement to seal the gas well producing layer and wellbore.

2. The continuous well sealing method with a fixed tubing string in a gas field according to claim 1, characterized in that, Step 1 specifically includes: Step 11: Select gas wells that have no production value or pose safety hazards as the initial target gas field old wells; Step 12: Select old gas field wells with two or more packers in the production tubing from the initial target gas field wells as the final target gas field wells to be plugged.

3. The continuous well sealing method with a fixed tubing string in a gas field according to claim 1, characterized in that, Step 2 specifically includes: Step 21: Use a well gauge to unclog the tubing to ensure unobstructed flow inside the tubing; Step 22: Use a tubing or cable to lower the retrievable tubing bridge plug to the predetermined position and set it.

4. The continuous well sealing method with a stationary tubing string in a gas field according to claim 1, characterized in that, Step 3 specifically includes: using a portable pressure testing pump to test the oil pipe above the retrievable bridge plug, with a test pressure of 15-25 MPa.

5. The continuous well sealing method with a stationary tubing string in a gas field according to claim 1, characterized in that, Step 4 specifically involves lowering a special retrieval tool for the retrieval bridge plug into the upper part of the retrieval bridge plug via an oil pipe or cable to retrieve the retrieval bridge plug.

6. The continuous well sealing method with a stationary tubing string in a gas field according to claim 1, characterized in that, Step 5 specifically involves circulating the wellbore cleaning agent through the tubing and using a positive circulation well washing method to clean the tubing and casing.

7. The continuous well sealing method with a stationary tubing string in a gas field according to claim 1, characterized in that, Step 6 specifically includes: Step 61: Place the permanent bridge plug in the upper part of the tool string inside the tubing, and use a cable or tubing to lower the permanent bridge plug setting tool and set the permanent bridge plug. Step 62: Use a portable pressure testing pump to test the wellhead tubing at a pressure of 15 MPa. After stabilizing the pressure for 30 minutes, ensure that the pressure drop is no more than 0.5 MPa.

8. The continuous well sealing method with a stationary tubing string in a gas field according to claim 1, characterized in that, Step 7 specifically includes: Step 71: Cement is squeezed into the annulus of the gas well through the gas well casing gate to seal the annulus and formation. Step 72: Conduct cementing quality testing on the sealed gas well from inside the tubing. For well sections where the sealing quality does not meet the sealing requirements, inject cement by drilling holes in the tubing. Step 73: Inject cement from the tubing to the wellhead to achieve cement sealing of the entire well section of the multi-sealing tubing string.

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