A replacement fluid steam injection insert pipe of a horizontal well thermal injection production pipe column

Abstract

This invention relates to a fluid displacement and steam injection pipe for a horizontal well insulated injection-production string. It includes a main body with an internal central channel, and a sealing section for sliding sealing with a release packer. The sealing section includes an upper sealing section and a lower sealing section distributed vertically. A lower smooth pipe section is provided on the main body between the upper and lower sealing sections, and the lower smooth pipe section has fluid displacement and steam injection holes communicating with the central channel. This invention provides a fluid displacement and steam injection pipe for a horizontal well insulated injection-production string, which has upper and lower sealing sections on the upper and lower sides of the fluid displacement and steam injection holes on the main body. This allows the fluid displacement and steam injection pipe to both displace fluid and inject steam, enabling the wellbore fluid above the release packer to be displaced before steam injection during production, avoiding high casing temperatures and effectively protecting the casing at high angles.

Description

Technical Field

[0001] This invention relates to oil production tools, and more specifically to a tubing used in conjunction with a drop packer on an insulated injection / production tubing string in a horizontal well. Background Technology

[0002] For steam injection and production of heavy oil horizontal wells, the traditional method uses an integrated injection and production tubing string with a thermally sensitive packer. However, the thermally sensitive packer on this type of tubing is prone to jamming during unsealing, affecting production. To overcome this drawback, existing technologies have developed injection and production tubing strings that work in conjunction with a drop-out packer. Such tubing strings can be found in the "Horizontal Well Inserted Sealing Insulated Injection and Production Drop-out Tubing String" disclosed in patent document CN203394487U. Its lower end of the insulated tubing is connected to a sealing insert. The sealing insert has a central channel communicating with the insulated tubing and has upper and lower openings. The sealing insert can slide and seal with the sealing cylinder inside the drop-out packer. In use, after inserting the front end of the sealing insert at the lower end of the insulated tubing into the sealing cylinder of the drop-out packer, the lower opening of the sealing insert is below the drop-out packer, allowing steam injection to be performed to achieve well shut-off and blowout.

[0003] The aforementioned existing technology, which uses a casing in conjunction with a drop packer, can only achieve steam injection. However, in actual production, it has been found that after frequent steam injection, a water layer will accumulate in the wellbore above the drop packer. During high-temperature steam injection, the liquid in the wellbore is heated, and the heat transfer will heat the casing. In addition, factors such as the high salinity of the formation water and the high temperature of steam injection (above 350°C) cause frequent corrosion of the casing in the steeply inclined section where the water accumulates, which seriously affects the normal production of the oil well. Summary of the Invention

[0004] The purpose of this invention is to provide a fluid replacement and steam injection insertion pipe for a horizontal well insulated injection and production string, so as to solve the technical problem that the existing technology cannot effectively protect the casing in the high-angle section during the production process.

[0005] This invention discloses a displacement and steam injection tubing for a horizontal well insulated injection-production string, comprising a tubing body with an internal central channel. The tubing body includes a sealing section for sliding and sealing with a drop-out packer. The sealing section includes an upper sealing section and a lower sealing section distributed vertically. A lower plain tubing section is provided on the tubing body between the upper and lower sealing sections. The lower plain tubing section has displacement and steam injection holes communicating with the central channel. The tubing body has a sealing structure below the displacement and steam injection holes that closes the lower end of the central channel. The lower sealing section is used to seal with the drop-out packer during displacement, so that the displacement and steam injection holes are in the space above the packer. The upper sealing section is used to seal with the drop-out packer during steam injection, so that the displacement and steam injection holes are in the space below the packer.

[0006] This invention provides a fluid replacement and steam injection pipe for a horizontal well insulated injection-production tubing string. It features upper and lower sealing sections on the upper and lower sides of the fluid replacement and steam injection ports on the main body of the pipe. This allows for two working states: the fluid replacement and steam injection ports are positioned above the packer while maintaining a seal between the main body and the packer; and the fluid replacement and steam injection ports are positioned below the packer. These correspond to the fluid replacement operation and the steam injection operation, respectively. Consequently, the fluid replacement and steam injection ports can be used to inject fluid replacement gas (nitrogen) into the space above the packer, causing wellbore fluid to return to the wellbore. They can also be used as steam injection ports to inject high-temperature steam into the space below the packer after fluid replacement is completed. Therefore, this fluid replacement and steam injection pipe can both replace fluid and inject steam, allowing for the removal of wellbore fluid above the packer during production before steam injection, preventing high casing temperatures and effectively protecting the casing at high angles.

[0007] Furthermore, the liquid replacement and steam injection holes are elongated grooves.

[0008] Furthermore, the liquid replacement and steam injection holes extend obliquely from the inside out and from top to bottom.

[0009] Furthermore, the outer diameter of the lower light tube section is smaller than the outer diameter of the sealing section, which is used to identify the relative position of the cannula body and the release packer.

[0010] Furthermore, an upper light tube section is provided above the upper sealing section. The outer diameter of the upper light tube section is smaller than the outer diameter of the sealing section, and the interior of the upper light tube section is a hollow channel.

[0011] Furthermore, the outer side of the lower sealing section has multiple annular grooves for installing the lower sealing ring, and the outer side of the upper sealing section has multiple annular grooves for installing the upper sealing ring.

[0012] Furthermore, the lower sealing section has a solid internal structure to form the sealing structure.

[0013] Furthermore, a guide cone is provided at the lower end of the lower sealing section. The guide cone is solid, and its outer surface is a cone-shaped surface that is larger at the top and smaller at the bottom.

[0014] Furthermore, the upper end of the cannula body is connected to a positioning and straightening device, which includes an upper connector and a positioning protrusion ring connected to the lower end of the upper connector. The positioning and straightening device has a central hole that passes through the upper connector and the positioning protrusion ring, and the outer diameter of the positioning protrusion ring is larger than the outer diameter of the cannula body.

[0015] Furthermore, the upper connector is provided with threads for connecting the tubing column, and the positioning protrusion ring is provided with threads for connecting the upper end of the insertion tube body. Attached Figure Description

[0016] Figure 1This is a structural schematic diagram of an embodiment of the present invention;

[0017] Figure 2 This is one of the usage state diagrams of an embodiment of the present invention;

[0018] Figure 3 This is a second schematic diagram illustrating the usage state of an embodiment of the present invention;

[0019] Figure 4 This is the third schematic diagram of the usage state of an embodiment of the present invention;

[0020] In the picture:

[0021] 1. Positioning and straightening device; 2. Upper smooth pipe section; 3. Upper sealing section; 4. Upper sealing ring; 5. Lower smooth pipe section; 6. Liquid replacement and steam injection hole; 7. Lower sealing section; 8. Lower sealing ring; 9. Guide cone; 100. Liquid replacement and steam injection pipe; 200. Hand-release packer. Detailed Implementation

[0022] An embodiment of the present invention provides a displacement steam injection pipe (hereinafter referred to as displacement steam injection pipe) for a horizontal well insulated injection and production string, as follows: Figures 1-4 As shown, the liquid-replacement vapor injection cannula 100 includes a cannula body with an internal central channel. The cannula body includes a sealing section for sliding sealing cooperation with the release packer 200. The sealing section includes an upper sealing section 3 and a lower sealing section 7 distributed vertically. A lower smooth tube section 5 is provided between the upper sealing section 3 and the lower sealing section 7. An upper smooth tube section 2 is provided above the upper sealing section 3. Thus, the cannula body includes the upper smooth tube section 2, the upper sealing section 3, the lower smooth tube section 5, and the lower sealing section 7 from top to bottom.

[0023] The upper end of the casing body is connected to a positioning and straightening device 1. The positioning and straightening device 1 includes an upper connector and a positioning convex ring connected to the lower end of the upper connector. The positioning and straightening device 1 has a central hole that passes through the upper connector and the positioning convex ring. The upper connector has threads for connecting the tubing string. The positioning convex ring has threads for connecting the upper tube section 2. The outer diameter of the positioning convex ring is larger than the outer diameter of the casing body. It is used to straighten the casing in the horizontal section to ensure that the sealing section of the casing body (the sealing section of the casing body includes the upper sealing section 3 and the lower sealing section 7) does not rub or collide with the well wall. Moreover, after the positioning and straightening device 1 contacts the top of the release packer 200, the load on the tubing string (i.e., the oil tubing, i.e. the production tubing string, hereinafter referred to as the tubing string) decreases, which can position the casing body.

[0024] The upper smooth tube section 2 has a smooth outer wall and an outer diameter smaller than that of the sealing sections (upper sealing section 3 and lower sealing section 7), and its interior is a hollow channel. The outer side of the upper sealing section 3 has multiple annular grooves for installing the upper sealing ring 4, and its interior is a hollow channel. It forms a seal with the sealing cylinder of the release packer 200 through the upper sealing ring 4. The upper smooth tube section 2 serves two purposes: first, it allows for thermal expansion of the tube string during steam injection, protecting the production tube string from bending or deformation; second, the outer diameter of the upper smooth tube section 2 is smaller than that of the sealing section. Thus, when the upper smooth tube section 2 and the upper sealing section 3 successively enter and exit the inner hole of the sealing cylinder of the release packer 200, different frictional forces are generated between the outer diameter of the insertion tube body and the sealing cylinder of the release packer 200 due to the change in the outer diameter of the insertion tube body. This results in a significant change in the axial load of the tube string, allowing the operator to judge whether the insertion tube has entered the release packer 200 and the mating position between the release packer 200 and the insertion tube body by observing the change in the axial load of the tube string.

[0025] The lower smooth tube section 5 has a smooth outer wall and an outer diameter smaller than that of the sealing section. Its interior is a hollow channel. The smaller outer diameter of the lower smooth tube section 5 also serves the same function as the upper smooth tube section 2, identifying the relative position of the insertion tube body and the release packer 200. The lower smooth tube section 5 has a liquid replacement and steam injection hole 6 communicating with the central channel. The liquid replacement and steam injection hole 6 is elongated and slotted to facilitate liquid replacement and steam injection. The liquid replacement and steam injection hole 6 extends sloping downwards from the inside out, which is beneficial for liquid ejection.

[0026] The outer side of the lower sealing section 7 has multiple annular grooves for installing the lower sealing ring 8. The interior of the lower sealing section 7 has a solid structure to form a sealing structure that closes the lower end of the central channel. The lower sealing section 7 forms a seal with the sealing cylinder of the release packer 200 through the lower sealing ring 8.

[0027] The lower sealing section 7 is also integrally provided with a guide cone 9. The guide cone 9 is solid, and the outer side of the guide cone 9 is a cone surface that is larger at the top and smaller at the bottom. It is used to guide the insertion body when it enters the release packer 200.

[0028] The aforementioned upper sealing ring 4 and lower sealing ring 8 are annular structures composed of graphite rings and polytetrafluoroethylene rings.

[0029] When the above embodiments of the present invention are used, Figure 2Before steam injection, the fluid replacement state is as follows: The release packer 200 is set in the horizontal section. The fluid replacement steam injection pipe 100 is connected to the production tubing (including insulated tubing and injection-production pump) to form a horizontal well insulated injection-production tubing (referred to as tubing string). The fluid replacement steam injection pipe 100 descends with the injection-production tubing string and enters the sealing cylinder of the release packer 200 (the release packer 200 is existing technology). The relative position of the fluid replacement steam injection pipe 100 and the release packer 200 is determined by the change in axial load of the tubing string, thereby determining whether the fluid replacement steam injection pipe 100 is in place. The lifting distance is calculated by the positioning device at the wellhead, so that the lower sealing section 7 of the fluid replacement steam injection pipe 100 seals with the sealing cylinder of the release packer 200. At this time, the wellbore is divided into two independent spaces with the release packer 200 as the boundary: the space above the packer and the space below the packer. Nitrogen gas is injected into the space above the packer 200 via the fluid replacement and steam injection ports 6 to perform fluid replacement, thereby returning most of the wellbore fluid above the packer 200 to the wellbore.

[0030] Figure 3 For steam injection, well shut-in, and blowout conditions: After fluid replacement is completed, continue lowering the tubing string connected to the fluid replacement and steam injection pipe 100, so that the upper sealing section 3 of the fluid replacement and steam injection pipe 100 seals with the sealing cylinder of the release packer 200. At this time, the fluid replacement and steam injection port 6 is below the release packer 200, and steam is injected into the space below the packer through the fluid replacement and steam injection port 6. At this time, the fluid replacement and steam injection pipe 100 and the release packer 200 effectively seal the steam injection channel, protecting the high-angle casing.

[0031] Figure 4 In the pumping production state: After the venting is completed, the tubing with the liquid-replacing steam injection tube 100 is lifted up, so that the liquid-replacing steam injection tube 100 is removed from the release packer 200. After the liquid-replacing steam injection tube 100 is removed from the release packer 200, subsequent pumping production can be carried out.

[0032] In other embodiments of the present invention, the lower sealing section in the above embodiments has a solid internal structure, forming a sealing structure that closes the lower end of the central channel. This sealing structure can also be replaced by being disposed in the lower optical tube section. Furthermore, the positioning and straightening device, the guide cone on the insertion tube body, and the upper optical tube section may be omitted. Embodiments formed by simple substitutions or obvious modifications listed above or similar are also embodiments of the technical solution of the present invention.

Claims

1. A fluid replacement and steam injection tube for a horizontal well insulated injection-production string, comprising a tube body with an internal central channel, the tube body including a sealing section for sliding sealing engagement with a release packer (200), characterized in that, The sealing section includes an upper sealing section (3) and a lower sealing section (7) distributed vertically. A lower smooth tube section (5) is provided on the main body of the insertion tube between the upper sealing section (3) and the lower sealing section (7). A liquid replacement and steam injection hole (6) communicating with the central channel is opened on the lower smooth tube section (5). A sealing structure is provided inside the main body of the insertion tube below the liquid replacement and steam injection hole (6) to close the lower end of the central channel. The lower sealing section (7) is used to seal with the release packer (200) when liquid replacement is performed so that the liquid replacement and steam injection hole (6) is in the packer. In the space above, the tubing is injected with nitrogen through the fluid replacement and steam injection holes into the space above the packer to perform fluid replacement, and most of the wellbore fluid above the packer is returned to the wellbore. The upper sealing section (3) is used to seal with the packer (200) when steam injection is performed, so that the fluid replacement and steam injection holes (6) are in the space below the packer, and the upper sealing section of the fluid replacement and steam injection pipe is sealed with the sealing cylinder of the packer. At this time, the fluid replacement and steam injection holes are below the packer, and the tubing is injected with steam into the space below the packer through the fluid replacement and steam injection holes.

2. The displacement steam injection tubing of the horizontal well insulated injection-production string according to claim 1, characterized in that, The liquid replacement and steam injection holes (6) are elongated grooves.

3. The displacement steam injection tubing for the horizontal well insulated injection-production string according to claim 2, characterized in that, The liquid replacement and steam injection holes (6) extend from the inside out and from top to bottom at an angle.

4. The fluid displacement and steam injection insertion pipe of the horizontal well insulated injection-production tubing according to claim 1, characterized in that, The outer diameter of the lower light tube section (5) is smaller than that of the sealing section and is used to identify the relative position of the cannula body and the release packer (200).

5. The fluid replacement and steam injection tubing of the horizontal well insulated injection-production string according to claim 1, characterized in that, Above the upper sealing section (3) is an upper light tube section (2), the outer diameter of the upper light tube section (2) is smaller than the outer diameter of the sealing section, and the interior of the upper light tube section (2) is a hollow channel.

6. The displacement steam injection tubing for the horizontal well insulated injection-production string according to claim 1, characterized in that, The outer side of the lower sealing section (7) has multiple annular grooves for installing the lower sealing ring (8), and the outer side of the upper sealing section (3) has multiple annular grooves for installing the upper sealing ring (4).

7. The fluid replacement and steam injection insertion pipe of the horizontal well insulated injection-production tubing according to claim 1, characterized in that, The lower sealing section (7) has a solid internal structure to form the sealing structure.

8. The fluid displacement and steam injection tubing of the horizontal well insulated injection-production string according to claim 7, characterized in that, The lower sealing section (7) is provided with a guide cone (9) at its lower end. The guide cone (9) is solid and its outer surface is a cone surface that is larger at the top and smaller at the bottom.

9. The fluid replacement and steam injection tubing for a horizontal well insulated injection-production string according to any one of claims 1-8, characterized in that, The upper end of the cannula body is connected to a positioning and straightening device (1). The positioning and straightening device (1) includes an upper connector and a positioning protrusion ring connected to the lower end of the upper connector. The positioning and straightening device (1) has a central hole that passes through the upper connector and the positioning protrusion ring. The outer diameter of the positioning protrusion ring is larger than the outer diameter of the cannula body.

10. The fluid replacement and steam injection tubing of the horizontal well insulated injection-production string according to claim 9, characterized in that, The upper connector is provided with threads for connecting the tubing column, and the positioning protrusion ring is provided with threads for connecting the upper end of the insertion tube body.

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