Tubular column structure for automatically injecting gas from high-pressure layer to low-pressure layer and control method

Abstract

The invention discloses a pipe column structure for automatically injecting gas from a high-pressure layer to a low-pressure layer and a control method. The technical problems that well completion operation is high in cost, large in process difficulty and the like are solved. The tubular column structure comprises a shaft sleeve, an isolation assembly, a filtering assembly and a gas injection assembly, and the gas injection assembly comprises a gas injection production tubular column arranged in the shaft sleeve; the production packer is arranged on the gas injection production pipe column and is fixed with the shaft casing pipe in a setting manner, and the production packer is positioned above the formation low-pressure layer; the injection allocation valve is arranged on the gas injection production pipe column and located below the production packer, and the injection allocation valve is located at the position of a low-pressure layer of the stratum; and the sealing part is connected to the bottom of the gas injection production tubular column and is in sealing connection with the isolation assembly. Natural energy of a high-pressure layer gas group of the same well can automatically flow to a low-pressure layer gas group, the recovery efficiency of the low-pressure layer gas group is improved, meanwhile, the cost can be saved, the well completion process difficulty is reduced, and layered mining can be conducted on an oil well in the later period.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas well engineering, and in particular relates to a pipe string structure and a control method for self-flowing gas injection from a high-pressure layer to a low-pressure layer. Background Art

[0002] With the continuous development of offshore oil and gas resources, the energy of the developed layers is gradually depleted, resulting in reduced recovery rates and poorer development results. Injecting gas into the depleted layers to replenish energy and maintain reservoir pressure is an effective measure to increase recovery rates and gas production rates.

[0003] Currently, gas injection wells collect and process gas through surface gas injection pipelines before injecting it into the formation. This method has certain limitations. First, it requires a surface gas source. Second, it requires a complete surface gas injection well network and supporting gas injection equipment. This method cannot meet the requirements of oil and gas fields with limited conditions, thus restricting their development. Furthermore, due to the large interlayer differences between the high- and low-pressure reservoirs in the formation, the completion process is demanding and needs to be improved. Summary of the Invention

[0004] In order to solve all or part of the above problems, the purpose of the present invention is to provide a pipe string structure and control method for self-flowing gas injection from high-pressure layers to low-pressure layers, which can realize the self-flow of natural energy from the high-pressure layer gas group to the low-pressure layer gas group in the same well, thereby improving the recovery rate of the low-pressure layer gas group. At the same time, it can also save costs, reduce the difficulty of well completion technology, and the oil well can be mined in layers in the later stage.

[0005] In a first aspect, the present invention provides a pipe column structure for self-flowing gas injection from a high-pressure layer to a low-pressure layer, comprising:

[0006] Wellbore casing, used to be lowered into the low-pressure layer of the formation;

[0007] an isolation assembly, disposed in the wellbore casing and used to separate the high-pressure layer and the low-pressure layer of the formation;

[0008] A filter assembly is connected to the bottom of the wellbore casing and extends to the high-pressure layer of the formation to support the well wall and prevent sand;

[0009] A gas injection assembly is disposed in the wellbore casing and is plugged and sealed with the isolation assembly;

[0010] The gas injection assembly comprises:

[0011] A gas injection production string is arranged in the wellbore casing;

[0012] A production packer is provided on the gas injection production string and is fixed to the wellbore casing, and the production packer is located above the low-pressure layer of the formation;

[0013] An injection valve is provided on the gas injection production string and is located below the production packer, and the injection valve is located at a low-pressure layer of the formation;

[0014] The sealing portion is connected to the bottom of the gas injection production string and is sealed with the isolation assembly.

[0015] Optionally, the gas injection assembly further includes:

[0016] A flow rate and pressure tester is connected to the gas injection production string and is located between the injection valve and the sealing portion. The flow rate and pressure tester is used to test the flow rate and pressure of the gas in the gas injection production string.

[0017] Optionally, the gas injection assembly further includes:

[0018] The safety valve is connected to the upper end of the gas injection production string and is used to control the emergency opening and closing of the gas injection production string.

[0019] Optionally, the sealing portion includes:

[0020] A landing joint connected to the bottom of the gas injection production string;

[0021] The isolation sealing unit is connected to the bottom of the seating joint and is sealed with the isolation assembly.

[0022] Optionally, the isolation assembly includes a formation isolation valve and a suspension packer, the formation isolation valve is connected to the bottom of the suspension packer, and together with the suspension packer separates the low-pressure layer and the high-pressure layer of the formation, and the sealing part is inserted and sealed with the sealing tube of the suspension packer.

[0023] Optionally, the filter assembly includes:

[0024] a filter screen, the top of which is located in the wellbore casing and the bottom of which extends to the high-pressure layer of the formation;

[0025] The tail pipe hanger is fixed to the top of the filter screen and is sealed and fixed with the wellbore casing.

[0026] In a second aspect, the present invention provides a method for controlling a pipe string structure, comprising the following steps:

[0027] S1, after drilling through the low-pressure layer of the formation with drilling equipment, the wellbore casing is lowered to perform casing completion operations;

[0028] S2, after drilling through the high-pressure layer of the formation using drilling equipment, select completion fluid compatible with the high-pressure layer of the formation to perform open hole completion;

[0029] S3, running the filter assembly to achieve open hole wall support and sand control;

[0030] S4, running the isolation assembly to separate the low-pressure layer from the high-pressure layer in the formation, replacing the completion fluid in the wellbore casing with a completion fluid compatible with the low-pressure layer in the formation, and perforating the wellbore casing at a position below the low-pressure layer in the formation to connect the low-pressure layer with the wellbore casing;

[0031] S5, lowering the gas injection assembly and connecting the gas injection assembly and the isolation assembly in an insert-sealed manner to construct a self-flowing gas injection channel between the high-pressure layer and the low-pressure layer of the formation;

[0032] S6, close the injection valve and control the isolation assembly to open and spray clean the high-pressure layer of the well;

[0033] S7, open the injection valve and spray clean the low-pressure layer of the well.

[0034] Optionally, in S4, when the isolation assembly is lowered, it is ensured that the formation isolation valve is in a closed state to achieve separation of the high-pressure layer and the low-pressure layer of the formation.

[0035] Optionally, the gas in the wellbore casing is tested by a flow pressure tester, or a monitoring tool string is lowered to the landing joint through a wireline operation to monitor formation parameters.

[0036] Optionally, the low-pressure layer of the formation is put into production by controlling the opening and closing of the injection valve, and the high-pressure layer is put into production by injecting a plug into the landing joint, so that the oil well has the ability to produce in layers.

[0037] As can be seen from the above technical solutions, the pipe column structure and control method for self-flowing gas injection from a high-pressure layer to a low-pressure layer provided by the present invention have the following advantages:

[0038] This tubing string structure and control method can realize the natural energy flow from the high-pressure gas layer group to the low-pressure gas layer group in the same well, thereby improving the recovery rate of the low-pressure gas layer group. At the same time, it can also save costs, reduce the difficulty of the well completion process, and the oil well can be mined in layers in the later stage.

[0039] Other features and advantages of the present invention will be set forth in the description that follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation to the technical solution of the present invention.

[0041] Figure 1 Schematic diagram of the overall structure of an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of the structure of the wellbore casing, isolation assembly and filter assembly in an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of the structure of the gas injection assembly in an embodiment of the present invention.

[0044] Description of reference numerals:

[0045] 1. Wellbore casing; 2. Isolation assembly; 21. Formation isolation valve; 22. Hanger packer; 3. Filter assembly; 31. Filter screen; 32. Tail pipe hanger; 4. Gas injection assembly; 41. Gas injection production string; 42. Safety valve; 43. Production packer; 44. Injection valve; 45. Flow and pressure tester; 46. Sealing part; 461. Landing joint; 462. Isolation sealing unit. DETAILED DESCRIPTION

[0046] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other in any manner.

[0047] like Figure 1 、 Figure 2 、 Figure 3 The figure shows an embodiment of the present invention, which discloses a tubular structure for self-flowing gas injection from a high-pressure layer to a low-pressure layer. The tubular structure includes a wellbore casing 1, an isolation assembly 2, a filter assembly 3, and a gas injection assembly 4. The wellbore casing 1 is used to be lowered into the low-pressure layer of the formation. The isolation assembly 2 is disposed within the wellbore casing 1 and is used to separate the high-pressure layer from the low-pressure layer of the formation. The filter assembly 3 is connected to the bottom of the wellbore casing 1 and extends to the high-pressure layer of the formation to support the wellbore wall and prevent sand. The gas injection assembly 4 is disposed within the wellbore casing 1 and connected to the isolation assembly 2 to construct a self-flowing gas injection channel between the high-pressure layer and the low-pressure layer of the formation.

[0048] In one embodiment, Figure 1 、 Figure 2 As shown, the isolation assembly 2 includes a formation isolation valve 21 and a suspension packer 22. The formation isolation valve 21 is installed within the wellbore casing 1 and is located between the low-pressure and high-pressure layers of the formation. The suspension packer 22 is set and fixed to the wellbore casing 1. The formation isolation valve 21 is connected to the bottom of the suspension packer 22. The suspension packer 22 and the formation isolation valve 21 jointly separate the high-pressure and low-pressure layers of the formation. The formation isolation valve 21 prevents interference between the high-pressure and low-pressure layers when the reservoir is opened.

[0049] In one embodiment, Figure 1 、 Figure 2As shown, filter assembly 3 includes a filter screen 31 and a liner hanger 32. The top of filter screen 31 is located within the wellbore casing 1, and its bottom extends to the high-pressure layer of the formation to filter oil and gas. Liner hanger 32 is fixed to the top of filter screen 31 and is sealed to the wellbore casing 1 to achieve a sealed connection between filter assembly 3 and isolation assembly 2.

[0050] In one embodiment, Figure 1 、 Figure 3 As shown, the gas injection assembly 4 includes a gas injection production string 41 and a safety valve 42, a production packer 43, an injection valve 44, a flow pressure tester 45 and a sealing part 46 connected to the gas injection production string 41 from top to bottom. The gas injection production string 41 is coaxially arranged in the wellbore casing 1 and is used as a gas injection and production channel. The safety valve 42 is used to control the emergency opening and closing of the gas injection production string 41 to meet the safety production requirements.

[0051] In one embodiment, Figure 1 、 Figure 3 As shown, the production packer 43 is fixed to the wellbore casing 1, and the production packer 43 is located above the low-pressure layer of the formation to meet production needs. The injection valve 44 is located at the low-pressure layer of the formation. As an adjustable downhole production control device, it can control the appropriate gas injection volume. The flow pressure tester 45 is used to test the flow and pressure of the gas in the gas injection production string 41. As a downhole flow monitoring device, it can monitor the output and injection volume at each stage. The sealing part 46 is plug-in sealed and connected to the suspension packer 2 to meet the needs of gas injection and subsequent stratified mining.

[0052] In one embodiment, Figure 1 、 Figure 3 As shown, the sealing part 46 includes a seating joint 461 and an isolation sealing unit 462. The seating joint 461 is connected to the bottom of the gas injection production tubing 41, and the isolation sealing unit 462 is connected to the bottom of the seating joint 461. The isolation sealing unit 462 is tightly inserted into the sealing tube of the suspension packer 22 to achieve a plug-in sealing connection between the two, thereby ensuring the connection stability and sealing effect of the two.

[0053] This embodiment also discloses a control method, using the above-mentioned string structure, comprising the following steps:

[0054] S1, after drilling through the low-pressure layer of the formation with drilling equipment, the wellbore casing 1 is lowered into the wellbore for casing completion operation.

[0055] S2, after drilling through the high-pressure layer of the formation with the drilling equipment, the completion fluid compatible with the high-pressure layer of the formation is selected to perform open hole completion. At this time, the high-pressure layer of the formation is in an open state.

[0056] S3, the filter screen 31 and the liner hanger 32 are connected to form the filter assembly 3, and then the filter assembly 3 is lowered to a predetermined position to perform simple sand control to achieve open hole well wall support and sand control.

[0057] S4, connect the suspension packer 22 and the formation isolation valve 21 to form an isolation assembly 2, and lower the isolation assembly 2 to a predetermined position between the high-pressure layer and the low-pressure layer of the formation, while ensuring that the formation isolation valve 21 is in a closed state, so that the formation isolation valve 21 and the suspension packer 22 can together separate the high-pressure and low-pressure layers of the formation.

[0058] After the isolation assembly 2 is lowered, the completion fluid in the wellbore casing 1 is replaced with a completion fluid that is compatible with the low-pressure layer of the formation, and the wellbore casing 1 is perforated at a position lower than the low-pressure layer of the formation to connect the low-pressure layer of the formation with the wellbore casing 1. At this time, due to the action of the formation isolation valve 21, there is no interference between the high-pressure and low-pressure layers of the formation.

[0059] S5, install the injection valve 44 and other components on the gas injection production string 41 to form the gas injection assembly 4, lower the gas injection assembly 4, and make the isolation sealing unit 462 and the suspension packer 22 form a plug-in sealing connection to construct a self-flowing gas injection channel between the high-pressure layer and the low-pressure layer of the formation.

[0060] S6, confirm that the formation isolation valve 21 is open, then open the formation isolation valve 21 to clean and flush the high-pressure layer of the well;

[0061] S7, confirm that the formation isolation valve 21 is open, then open the injection valve 44 to clean and spray the low-pressure layer of the well.

[0062] The gas in the wellbore casing 1 is tested using a flow and pressure tester 45, or a monitoring tool string is run through a slickline operation to the landing joint 461 to monitor formation parameters. Simultaneously, the injection valve 44 is controlled to open and close to control whether the low-pressure layer in the formation is put into production, and a plugging device is deployed to the landing joint 461 to control whether the high-pressure layer is put into production, thereby enabling the oil well to achieve stratified production capabilities.

[0063] The pipe column structure and control method for self-flowing gas injection from the high-pressure layer to the low-pressure layer in this embodiment can control the self-flowing gas injection from the high-pressure layer to the low-pressure layer, use the gas from the high-pressure layer of an oil and gas well as the injection gas source, and self-flow and self-inject energy into the low-pressure layer of the same oil well, thereby improving the recovery rate and reducing the huge investment cost of improving the gas injection pipeline network equipment.

[0064] Overall, this method achieves safe stratified completion in reservoirs with significant pressure differences between the two layers, avoiding reservoir interference and ensuring reservoir protection. It also establishes migration pathways for self-flowing gas injection and provides flow assurance control. Furthermore, the string structure, combined with monitoring equipment, enables testing and evaluation of gas injection capacity and meets the needs of subsequent stratified production in low- and high-pressure layers.

[0065] It should be noted that, unless otherwise specified, the technical or scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0066] In addition, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. In the description of the present invention, "plurality" means more than two, unless otherwise specifically defined.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A pipe column structure for self-flowing gas injection from a high-pressure layer to a low-pressure layer, characterized in that: include: A wellbore casing (1) is used to be lowered into a low-pressure layer of the formation; An isolation assembly (2) is disposed in the wellbore casing (1) and is used to separate a high-pressure layer and a low-pressure layer of the formation; A filter assembly (3) is connected to the bottom of the wellbore casing (1) and extends to the high-pressure layer of the formation to support the well wall and prevent sand; A gas injection assembly (4) is disposed in the wellbore casing (1) and is inserted into and sealed with the isolation assembly (2); The gas injection assembly (4) comprises: A gas injection production string (41) is arranged in the wellbore casing (1); A production packer (43) is provided on the gas injection production string (41) and is fixedly sealed with the wellbore casing (1), and the production packer (43) is located above the low-pressure layer of the formation; An injection valve (44) is provided on the gas injection production string (41) and is located below the production packer (43), and the injection valve (44) is located at a low-pressure layer of the formation; The sealing portion (46) is connected to the bottom of the gas injection production string (41) and is sealed to the isolation assembly (2).

2. The pipe column structure according to claim 1, characterized in that: The gas injection assembly (4) further comprises: A flow pressure tester (45) is connected to the gas injection production string (41) and is located between the injection valve (44) and the sealing portion (46). The flow pressure tester (45) is used to test the flow and pressure of the gas in the gas injection production string (41).

3. The pipe column structure according to claim 1, characterized in that: The gas injection assembly (4) further comprises: The safety valve (42) is connected to the upper end of the gas injection production string (41) and is used to control the emergency opening and closing of the gas injection production string (41).

4. The pipe column structure according to claim 1, characterized in that: The sealing portion (46) comprises: A landing joint (461) connected to the bottom of the gas injection production string (41); An isolation sealing unit (462) is connected to the bottom of the seating joint (461) and is sealed to the isolation assembly (2).

5. The pipe column structure according to claim 1, characterized in that: The isolation assembly (2) includes a formation isolation valve (21) and a suspension packer (22), wherein the formation isolation valve (21) is connected to the bottom of the suspension packer (22) and, together with the suspension packer (22), separates the low-pressure layer and the high-pressure layer of the formation, and the sealing portion (46) is plug-in sealedly connected to the sealing cylinder of the suspension packer (22).

6. The pipe column structure according to claim 1, characterized in that: The filter assembly (3) comprises: A filter screen (31), the top of which is located in the wellbore casing (1) and the bottom of which extends to the high-pressure layer of the formation; The tail pipe hanger (32) is fixed to the top of the filter screen (31) and is sealed and fixed to the wellbore casing (1).

7. A method for controlling a pipe string structure according to any one of claims 1 to 6, characterized in that: The steps include: S1, after drilling through the low-pressure layer of the formation with drilling equipment, the wellbore casing (1) is lowered to perform casing completion operation; S2, after drilling through the high-pressure layer of the formation using drilling equipment, select completion fluid compatible with the high-pressure layer of the formation to perform open hole completion; S3, lowering the filter assembly (3) to achieve open hole wall support and sand control; S4, lowering the isolation assembly (2) to separate the low-pressure layer and the high-pressure layer of the formation, replacing the completion fluid in the wellbore casing (1) with a completion fluid suitable for the low-pressure layer of the formation, and perforating the wellbore casing (1) at a position lower than the low-pressure layer of the formation to connect the low-pressure layer of the formation with the wellbore casing (1); S5, lowering the gas injection assembly (4), and inserting and sealing the gas injection assembly (4) with the isolation assembly (2) to construct a self-flowing gas injection channel between the high-pressure layer and the low-pressure layer of the formation; S6, close the injection valve (44), control the isolation assembly (2) to open, and clean the high-pressure layer of the well; S7, open the injection valve (44) to clean the low-pressure layer of the well.

8. The control method according to claim 7, characterized in that: In S4, when the isolation assembly (2) is lowered, it is ensured that the formation isolation valve (21) is in a closed state to achieve separation of the high-pressure layer and the low-pressure layer of the formation.

9. The control method according to claim 7, characterized in that: The gas in the wellbore casing (1) is tested by a flow pressure tester (45), or a monitoring tool string is lowered into the landing joint (461) through a steel wire operation to monitor formation parameters.

10. The control method according to claim 7, characterized in that: By controlling the opening and closing of the injection valve (44), the low-pressure layer of the formation is controlled to be put into production, and by injecting the plug into the landing joint (461), the high-pressure layer is controlled to be put into production, so that the oil well has the ability of layered production.

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