A double-sleeve anti-backflow steam injection string

Abstract

The present invention provides a double-sleeve steam injection string with backflow prevention, comprising a telescopic pipe, an insulated pipe a, a double-sleeve steam injection valve, an insulated pipe b, a check valve steam injection valve, an insulated pipe c, and a plug connected in sequence. The outer walls of the insulated pipes a and b are each sleeved with a thermally sensitive packer. The double-sleeve steam injection valve comprises a hollow valve body a, a steam injection port defined in the sidewall of the valve body a, a sleeve b disposed within the valve body a and sealing the steam injection port, a shear pin b disposed between the sidewalls of the sleeve b and the sidewalls of the valve body a, a valve seat b fixedly connected within the sleeve b, and a valve ball b positioned within the sleeve b. The sleeve a is disposed within the valve body a and positioned above the sleeve b, a shear pin a disposed between the sidewalls of the sleeve a and the sidewalls of the valve body a, a valve seat a fixedly connected within the sleeve a, and a valve ball a positioned within the sleeve a. The present invention can prevent steam backflow after steam injection, thus avoiding heat diffusion in non-producing strata and facilitating crude oil production.

Description

Technical Field

[0001] The invention belongs to the technical field of oil production engineering, and relates to a steam injection string for a steam-huffing oil well, and in particular to a double-sleeve type backflow-proof steam injection string. Background Art

[0002] Currently, Shuguang Oilfield primarily produces oil through steam stimulation, with staged steam injection as the primary method. However, during the soaking phase, the steam injection valves do not close properly, allowing steam to flow back into the tubing, dissipating heat to non-productive layers and resulting in significant energy loss. Although nitrogen injection insulation technology is employed, it is currently only used in the annulus of the casing, and the insulation effect is poor due to a loose seal. Insulation jackets are used on the surface, but due to frequent use and improper bundling, some energy is lost, hindering crude oil production. Summary of the Invention

[0003] In order to solve the problem of energy loss caused by backflow when steam is injected into the steam injection string during the well shut-in stage in the existing technology, the present invention provides a double-sleeve anti-backflow steam injection string, which can prevent steam from being spit out after the steam injection is completed, avoiding heat diffusion in non-producing layers, and facilitating crude oil production.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a double-sleeve anti-backflow steam injection string, comprising a telescopic pipe, a thermal packer a, a double-sleeve steam injection valve, a thermal packer b, a check valve steam injection valve, a plug, an insulation pipe a, an insulation pipe b, and an insulation pipe c;

[0005] The telescopic tube is connected to one end of the insulation tube a, the other end of the insulation tube a is connected to one end of the double-sleeve steam injection valve, the other end of the double-sleeve steam injection valve is connected to one end of the insulation tube b, the other end of the insulation tube b is connected to one end of the check valve steam injection valve, the other end of the check valve steam injection valve is connected to one end of the insulation tube c, and the other end of the insulation tube c is provided with a wire plug; the thermal packer a is sleeved on the outer wall of the insulation tube a, and the thermal packer b is sleeved on the outer wall of the insulation tube b;

[0006] The double-sleeve steam injection valve comprises a valve body a, a shear pin a, a valve ball a, a valve seat a, a sleeve a, a sleeve b, a steam injection port, a shear pin b, a valve ball b, and a valve seat b; the valve body a is hollow inside, and a steam injection port is provided on its side wall; the sleeve b is arranged inside the valve body a and is sealed at the steam injection port; a shear pin b is provided between the side wall of the sleeve b and the side wall of the valve body a; the sleeve b is fixedly connected to the valve seat b; a through hole b is provided in the middle of the valve seat b, and the diameter of the through hole b is smaller than that of the valve The diameter of the ball b is such that when the valve ball b is put into the sleeve b, it is clamped in the through hole b; the sleeve a is arranged inside the valve body a and is located above the sleeve b, and a shear pin a is provided between the side wall of the sleeve a and the side wall of the valve body a. The sleeve a is fixedly connected to the valve seat a, and a through hole a is provided in the middle of the valve seat a. The diameter of the through hole a is smaller than the diameter of the valve ball a. When the valve ball a is put into the sleeve a, it is clamped in the through hole a; the diameter of the through hole a is larger than the diameter of the valve ball b.

[0007] As a further embodiment of the present invention, the double-sleeve steam injection valve further includes a sealing ring a and a sealing ring b; a sealing ring b is provided between the sliding sleeve b and the inner wall of the valve body a, and a sealing ring a is provided between the sliding sleeve a and the inner wall of the valve body a.

[0008] As a further embodiment of the present invention, the one-way valve type steam injection valve includes a valve body b, a main steam injection channel, a steam injection channel, a valve seat c, a valve ball c, and a valve cover; the interior of the valve body b is hollow to form the main steam injection channel, and the middle part of the valve body b is provided with an annular protrusion extending outward, and the annular protrusions on both sides of the valve body b are respectively provided with a steam injection channel connected to the main steam injection channel, the steam injection channel is fixedly connected with a valve seat c, the end of the steam injection channel is fixedly connected with a valve cover, and the valve ball c is floatingly arranged between the valve cover and the valve seat c; a through hole c is provided in the middle part of the valve seat c, and the diameter of the through hole c is smaller than the diameter of the valve ball c.

[0009] As a further embodiment of the present invention, the steam injection channel is L-shaped.

[0010] As a further embodiment of the present invention, one end of the valve body b is provided with an internal thread, and the other end is provided with an external thread.

[0011] As a further embodiment of the present invention, the number of the sealing rings b is two, located at both sides of the steam injection port; the number of the sealing rings a is two, located at both ends of the sleeve a.

[0012] As a further embodiment of the present invention, one end of the valve body a is provided with an internal thread, and the other end is provided with an external thread.

[0013] As a further embodiment of the present invention, the telescopic tube is connected to one end of the insulation tube a through a thread.

[0014] The present invention has the following beneficial effects: Currently, during crude oil steam huff and puff, when steam injection is stopped or injected into other oil layers, steam backflow occurs, causing heat to diffuse into non-producing layers, hindering normal production and increasing the insulation workload at the surface wellhead. The present invention provides a double-sleeve, backflow-proof steam huff and puff injection string that prevents steam backflow after steam injection, avoiding heat diffusion into non-producing layers, facilitating crude oil production, and improving heat utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0016] Figure 2 This is a cross-sectional view of the structure of a one-way valve type steam injection valve of the present invention;

[0017] Figure 3 It is a cross-sectional view of the structure of the double-sleeve steam injection valve of the present invention.

[0018] Explanation of reference numerals in the figure: 1, telescopic tube, 2, thermal packer a, 3, double-sleeve steam injection valve, 4, thermal packer b, 5, check valve steam injection valve, 6, plug, 7, insulation pipe a, 8, insulation pipe b, 9, insulation pipe c,

[0019] 3-1, valve body a, 3-2, sealing ring a, 3-3, shear pin a, 3-4, valve ball a, 3-5, valve seat a, 3-6, sleeve b, 3-7, sealing ring b, 3-8, steam injection port, 3-9, shear pin b, 3-10, valve ball b, 3-11, valve seat b, 3-12, sleeve a,

[0020] 5-1. Valve body b, 5-2. Main steam injection channel, 5-3. Steam injection channel, 5-4. Valve seat c, 5-5. Valve ball c, 5-6. Valve cover. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used solely to distinguish components and should not be construed as indicating or implying relative importance.

[0023] In addition, 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.

[0024] Example 1

[0025] A double-sleeve type anti-backflow steam injection string prevents steam injected into the target layer from being spit back into the string, comprising a telescopic pipe 1, a thermal packer a2, a double-sleeve type steam injection valve 3, a thermal packer b4, a check valve type steam injection valve 5, a plug 6, an insulation pipe a7, an insulation pipe b8, and an insulation pipe c9;

[0026] The telescopic tube 1 is connected to one end of the insulation tube a7 by a thread, the other end of the insulation tube a7 is connected to one end of the double-sleeve steam injection valve 3, the other end of the double-sleeve steam injection valve 3 is connected to one end of the insulation tube b8, the other end of the insulation tube b8 is connected to one end of the check valve steam injection valve 5, the other end of the check valve steam injection valve 5 is connected to one end of the insulation tube c9, and the other end of the insulation tube c9 is provided with a threaded plug 6;

[0027] In the above embodiment, the thermal packer a2 is sleeved on the middle portion of the outer wall of the thermal insulation tube a7, and the thermal packer b4 is sleeved on the middle portion of the outer wall of the thermal insulation tube b8.

[0028] The double-sleeve steam injection valve 3 includes a valve body a3-1, a sealing ring a3-2, a shear pin a3-3, a valve ball a3-4, a valve seat a3-5, a sliding sleeve a3-12, a sliding sleeve b3-6, a sealing ring b3-7, a steam injection port 3-8, a shear pin b3-9, a valve ball b3-10, and a valve seat b3-11;

[0029] The valve body a3-1 is hollow, with one end having an internal thread and the other end having an external thread, to facilitate connection with other components at both ends. A steam injection port 3-8 is provided on the side wall of the valve body a3-1. A sliding sleeve b3-6 is disposed within the valve body a3-1 and seals against the steam injection port 3-8. A shear pin b3-9 is provided between the side wall of the sliding sleeve b3-6 and the side wall of the valve body a3-1 to secure the position of the sliding sleeve b3-6 within the valve body a3-1.

[0030] Preferably, a sealing ring b3-7 is provided between the sliding sleeve b3-6 and the inner wall of the valve body a3-1. Two sealing rings b3-7 are provided, one on each side of the steam injection port 3-8, to ensure sealing during the steam injection process.

[0031] A radially arranged valve seat b3-11 is provided inside the sleeve b3-6, and the outer wall of the valve seat b3-11 is fixedly connected to the inner wall of one end of the sleeve b3-6. A through hole b is opened in the middle of the valve seat b3-11. The diameter of through hole b is smaller than that of the valve ball b3-10. When the valve ball b3-10 is inserted into the sleeve b3-6, it is locked in the through hole b.

[0032] The sliding sleeve a3-12 is disposed inside the valve body a3-1 and above the sliding sleeve b3-6. A shear pin a3-3 is provided between the side wall of the sliding sleeve a3-12 and the side wall of the valve body a3-1 to secure the position of the sliding sleeve a3-12 within the valve body a3-1.

[0033] Preferably, a sealing ring a3-2 is provided between the sliding sleeve a3-12 and the inner wall of the valve body a3-1. Two sealing rings a3-2 are provided, one at each end of the sliding sleeve a3-12, to ensure sealing during the steam injection process.

[0034] A radially arranged valve seat a3-5 is provided inside the sleeve a3-12, and the outer wall of the valve seat a3-5 is fixedly connected to the inner wall of one end of the sleeve a3-12. A through hole a is opened in the middle of the valve seat a3-5. The diameter of the through hole a is smaller than that of the valve ball a3-4. When the valve ball a3-4 is inserted into the sleeve a3-12, it is engaged at the through hole a.

[0035] In order to allow the valve ball b3-10 to be smoothly inserted into the sliding sleeve b3-6, the diameter of the through hole a is larger than the diameter of the valve ball b3-10.

[0036] The one-way valve type steam injection valve 5 includes a valve body b5-1, a main steam injection channel 5-2, a steam injection channel 5-3, a valve seat c5-4, a valve ball c5-5, and a valve cover 5-6;

[0037] The valve body b5-1 is hollow inside, forming the main steam injection channel 5-2; one end of the valve body b5-1 is provided with an internal thread, and the other end is provided with an external thread to facilitate connection with other components at both ends;

[0038] An annular protrusion extending outward is provided in the middle of the valve body b5-1, and an L-shaped steam injection channel 5-3 connected to the main steam injection channel 5-2 is respectively provided in the annular protrusions on both sides of the valve body b5-1. A valve seat c5-4 is fixedly connected to the steam injection channel 5-3, and a valve cover 5-6 is fixedly connected to the end of the steam injection channel 5-3. The valve ball c5-5 is floatingly arranged between the valve cover 5-6 and the valve seat c5-4; a through hole c is provided in the middle of the valve seat c5-4, and the diameter of the through hole c is smaller than the diameter of the valve ball c5-5.

[0039] During operation, after the tubing string is lowered into the wellbore to the designed position, steam is injected into the string to set thermal packers a2 and b4. Steam then flows through the steam injection channel 5-3 of the check valve steam injection valve 5, through the valve ball c5-5, and the valve cover 5-6, injecting the designed amount of steam into the target zone. Once the designed amount of steam has been injected, the valve ball b3-10 is inserted into the string. When the pressure reaches the shear pressure of the shear pin b3-9, the sleeve b3-6 slides down the inner wall of the valve body a3-1, opening the steam injection port 3-8 and injecting the designed amount of steam into the target zone. At this point, the pressure above the valve ball c5-5 is lower than the pressure below it. The steam below the valve ball c5-5 causes it to tightly contact the valve seat c5-4, preventing the steam injected into the target zone from being regurgitated. This ensures the steam injection rate into the target zone and facilitates crude oil production.

[0040] When the double-sleeve steam injection valve 3 reaches the designed amount of steam, the valve ball a3-4 is inserted into the pipe string. Under the action of pressure, the shear pin a3-3 is sheared off, and the sliding sleeve a3-12 moves down along the inner wall of the valve body a3-1 to block the steam injection port 3-8, preventing the steam in the target layer from leaking into the pipe string.

[0041] Since the amount of steam inside the string is much less than that inside a conventional steam injection string, steam waste is reduced, which is beneficial to crude oil production and reduces heat transfer to non-productive layers.

[0042] When the production layer is soaked for a certain period of time, as the temperature drops, the thermal packers a2 and b4 shrink, making the casing annular space connected from top to bottom. When the casing annular space is large enough to allow the tubing to be lifted, the steam injection string is pulled out and the production string is lowered, and the crude oil officially enters the production stage.

[0043] The double-sleeve anti-backflow steam injection string described in the above embodiment can prevent steam from being spit out after steam injection, thereby avoiding heat diffusion in non-producing layers, facilitating crude oil production, and improving heat utilization.

[0044] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A double-sleeve anti-backflow steam injection string, characterized in that: It comprises a telescopic pipe (1), a thermal packer a (2), a double-sleeve steam injection valve (3), a thermal packer b (4), a check valve steam injection valve (5), a plug (6), a thermal insulation pipe a (7), a thermal insulation pipe b (8), and a thermal insulation pipe c (9); The telescopic tube (1) is connected to one end of the thermal insulation tube a (7), the other end of the thermal insulation tube a (7) is connected to one end of the double-sleeve steam injection valve (3), the other end of the double-sleeve steam injection valve (3) is connected to one end of the thermal insulation tube b (8), the other end of the thermal insulation tube b (8) is connected to one end of the check valve steam injection valve (5), the other end of the check valve steam injection valve (5) is connected to one end of the thermal insulation tube c (9), and the other end of the thermal insulation tube c (9) is provided with a wire plug (6); the thermal sensitive packer a (2) is sleeved on the outer wall of the thermal insulation tube a (7), and the thermal sensitive packer b (4) is sleeved on the outer wall of the thermal insulation tube b (8); The double-sleeve steam injection valve (3) comprises a valve body a (3-1), a shear pin a (3-3), a valve ball a (3-4), a valve seat a (3-5), a sleeve a (3-12), a sleeve b (3-6), a steam injection port (3-8), a shear pin b (3-9), a valve ball b (3-10), and a valve seat b (3-11); the valve body a (3-1) is hollow inside, and a steam injection port (3-8) is provided on its side wall; the sleeve b (3-6) is arranged inside the valve body a (3-1) and is sealed at the steam injection port (3-8); a shear pin b (3-9) is provided between the side wall of the sleeve b (3-6) and the side wall of the valve body a (3-1); the sleeve b (3-6) is fixedly connected to the valve seat b (3-11) inside, and the middle of the valve seat b (3-11) is provided with a A through hole b is provided, the diameter of the through hole b is smaller than the diameter of the valve ball b (3-10), and when the valve ball b (3-10) is put into the sliding sleeve b (3-6), it is clamped at the through hole b; the sliding sleeve a (3-12) is arranged inside the valve body a (3-1) and is located above the sliding sleeve b (3-6), a shear pin a (3-3) is provided between the side wall of the sliding sleeve a (3-12) and the side wall of the valve body a (3-1), the sliding sleeve a (3-12) is fixedly connected with the valve seat a (3-5), and a through hole a is opened in the middle of the valve seat a (3-5), the diameter of the through hole a is smaller than the diameter of the valve ball a (3-4), and when the valve ball a (3-4) is put into the sliding sleeve a (3-12), it is clamped at the through hole a; the diameter of the through hole a is larger than the diameter of the valve ball b (3-10); The one-flow valve type steam injection valve (5) comprises a valve body b (5-1), a main steam injection channel (5-2), a steam injection channel (5-3), a valve seat c (5-4), a valve ball c (5-5), and a valve cover (5-6); the valve body b (5-1) is hollow inside to form the main steam injection channel (5-2); the middle of the valve body b (5-1) is provided with an annular protrusion extending outward, and the annular protrusions on both sides of the valve body b (5-1) are provided with a protrusion extending outward. A steam injection channel (5-3) is provided in each of the two valves and is connected to the main steam injection channel (5-2). A valve seat c (5-4) is fixedly connected to the steam injection channel (5-3). A valve cover (5-6) is fixedly connected to the end of the steam injection channel (5-3). A valve ball c (5-5) is floatingly arranged between the valve cover (5-6) and the valve seat c (5-4). A through hole c is provided in the middle of the valve seat c (5-4). The diameter of the through hole c is smaller than the diameter of the valve ball c (5-5).

2. The double-sleeve anti-backflow steam injection string according to claim 1, characterized in that: The double-sleeve steam injection valve (3) further comprises a sealing ring a (3-2) and a sealing ring b (3-7); a sealing ring b (3-7) is provided between the sliding sleeve b (3-6) and the inner wall of the valve body a (3-1), and a sealing ring a (3-2) is provided between the sliding sleeve a (3-12) and the inner wall of the valve body a (3-1).

3. The double-sleeve anti-backflow steam injection string according to claim 1, characterized in that: The steam injection channel (5-3) is L-shaped.

4. The double-sleeve anti-backflow steam injection string according to claim 1, characterized in that: One end of the valve body b (5-1) is provided with an internal thread, and the other end is provided with an external thread.

5. The double-sleeve anti-backflow steam injection string according to claim 2, characterized in that: The sealing rings b (3-7) are provided in two numbers and are respectively located at both sides of the steam injection port (3-8); the sealing rings a (3-2) are provided in two numbers and are respectively located at both ends of the sliding sleeve a (3-12).

6. The double-sleeve anti-backflow steam injection string according to claim 1, characterized in that: One end of the valve body a (3-1) is provided with an internal thread, and the other end is provided with an external thread.

7. The double-sleeve anti-backflow steam injection string according to claim 1, characterized in that: The telescopic tube (1) is connected to one end of the heat insulation tube a (7) via a thread.

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