Deep geothermal single well heat exchange system in abandoned oil well

Abstract

The utility model belongs to the technical field of abandoned oil well transformation, and particularly relates to a deep geothermal single well heat exchange system in an abandoned oil well, which comprises a sandstone heat reservoir and a production layer sleeve, a plurality of water inlet holes corresponding to the sandstone heat reservoir penetrate through the side wall of the production layer sleeve, and a branch pipeline inclining downwards is connected to the side wall of the production layer sleeve. The lower end of the branch pipeline extends into a sandstone thermal reservoir, the lower end of the inner side of the production layer casing pipe is connected with an artificial well bottom, the inner side of the production layer casing pipe is further connected with a packer located on the lower side of a port of the branch pipeline, the upper end of the inner side of the production layer casing pipe is provided with a booster water pump and a shell-and-tube heat exchanger, and a water inlet of the booster water pump is connected with a water production tubular column. The lower end of the water extraction pipe column extends into the sandstone heat reservoir, and a water outlet of the booster water pump is connected with the shell-and-tube heat exchanger through a lifting pipe. The device is convenient to install and maintain and high in heat energy utilization rate.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of middle-deep geothermal single well heat exchange systems in abandoned oil well, belong to abandoned oil well modification technical field. BACKGROUND

[0002] With the continuous exploitation of oil and gas, the number of abandoned oil wells in China is increasing. After the previous oil well exploitation is completed, it is usually abandoned by shutting down. Not only does it require a lot of manpower and material resources to maintain the abandoned oil well, but it also wastes land resources. Therefore, the clean transformation and utilization of abandoned oil wells have become a problem that enterprises need to solve urgently. The depth of oil wells is generally more than 2000 meters, and the depth of some oil wells can even reach 3000 meters. The utilization prospect of underground heat energy is very promising.

[0003] For example, the Chinese utility model patent with the authorization announcement number CN215909466U discloses a non-interference downhole heat exchanger for converting abandoned wells into geothermal wells. Although it realizes the transformation and utilization of abandoned oil wells, the porous heat exchange pipe, plug and other heat exchange related structures need to be lowered into the middle-deep geothermal source of the abandoned oil well, which is difficult to install. Moreover, the contact area between the porous heat exchange pipe and the heat source is small, so the heat exchange effect is not good, and the heat energy utilization rate is low. SUMMARY

[0004] In view of the above shortcomings of the prior art, the technical problem to be solved by the present utility model is to provide a middle-deep geothermal single well heat exchange system for abandoned oil wells, which is easy to install and has a high heat energy utilization rate.

[0005] The middle-deep geothermal single well heat exchange system for abandoned oil wells comprises a sandstone thermal reservoir and a production layer casing. A plurality of water inlet holes corresponding to the sandstone thermal reservoir are formed in the side wall of the production layer casing. A downwardly inclined branch pipe is connected to the side wall of the production layer casing. The lower end of the branch pipe extends into the sandstone thermal reservoir. An artificial well bottom is sealingly connected to the inner side of the lower end of the production layer casing. A packer is connected to the inner side of the production layer casing below the port of the branch pipe. A booster water pump and a tube-shell heat exchanger are installed at the upper end of the inner side of the production layer casing. A water sampling pipe column is connected to the water inlet of the booster water pump. The lower end of the water sampling pipe column extends through the packer and into the sandstone thermal reservoir. A water lifting pipe is connected to the water outlet of the booster water pump. The other end of the water lifting pipe is connected to the tube-shell heat exchanger.

[0006] Further, the artificial well bottom is cement filled at the lower end of the production layer casing.

[0007] Furthermore, the shell-and-tube heat exchanger includes a shell and a cover plate. The top and bottom of the shell are respectively provided with an upper sealing plate and a lower sealing plate. The cover plate is connected to the end of the shell sleeve. The bottom of the cover plate is fixedly connected to an upper tube box and a sleeve. The cover plate is provided with a tube-side medium inlet that communicates with the sleeve and a tube-side medium outlet that communicates with the upper tube box. The sleeve is located inside the upper tube box. Both the upper tube box and the sleeve are sealed to the upper sealing plate. The bottom of the lower sealing plate is sealed to a lower tube box. The lower tube box is provided with a shell-side medium inlet and a shell-side medium outlet that penetrate its body. The upper end of the shell-side medium inlet penetrates the lower sealing plate and extends to the lower end of the shell. The upper end of the shell-side medium outlet penetrates the lower sealing plate and extends to the upper end of the shell. Multiple primary heat exchange tubes that communicate with the sleeve and the lower tube box and multiple secondary heat exchange tubes that communicate with the upper tube box and the lower tube box are connected between the upper sealing plate and the lower sealing plate.

[0008] Furthermore, the cover plate has through holes for threading.

[0009] Furthermore, the top of the upper sealing plate is provided with a positioning platform that corresponds to and is adapted to the sleeve.

[0010] Working principle and process:

[0011] In operation, hot water from the sandstone geothermal reservoir enters the production casing through the inlet. The artificial well bottom can seal the lower end of the production casing to isolate the oil-producing and water-producing zones, preventing contamination of the water layer by the oil layer. A booster pump drives the hot water from the production casing through the production tubing, riser pipe, and shell-side medium inlet into the shell. After heat exchange within the shell, the hot water is discharged through the shell-side medium outlet onto the packer, then flows back along branch pipes to the distant sandstone geothermal reservoir to prevent thermal breakthrough. External water enters the primary heat exchanger tube through the tube-side medium inlet and the casing, where it undergoes primary heat exchange with the hot water in the shell. It then flows to the lower tube box and then to the secondary heat exchanger tube for secondary heat exchange with the hot water in the shell. After secondary heating, the external water flows out through the upper tube box and tube-side medium outlet, and is further transported to heat users.

[0012] The advantages of this utility model compared with the prior art are:

[0013] The deep geothermal single-well heat exchange system in the abandoned oil well described in this utility model has both the shell-and-tube heat exchanger and the booster pump installed at the wellhead, which facilitates installation and maintenance.

[0014] The deep geothermal single-well heat exchange system in abandoned oil wells described in this utility model has a primary heat exchange tube and a secondary heat exchange tube that are completely surrounded and covered by the heat source, resulting in a large contact area with the heat source. Therefore, the heat exchange efficiency is high, which effectively improves the thermal energy utilization rate of sandstone thermal reservoirs. Attached Figure Description

[0015] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model;

[0016] Figure 2 yes Figure 1 A magnified view of point M in the middle.

[0017] In the diagram: 1. Artificial well bottom; 2. Production layer casing; 3. Sandstone thermal reservoir; 4. Inlet; 5. Production tubing; 6. Branch pipe; 7. Shell-side medium outlet; 8. Lower casing box; 9. Shell; 10. Shell-side medium inlet; 11. Packer; 12. Booster pump; 13. Pump pipe; 14. Primary heat exchanger tube; 15. Secondary heat exchanger tube; 16. Lower sealing plate; 17. Tube-side medium inlet; 18. Tube-side medium outlet; 19. Sleeve; 20. Upper casing box; 21. Upper sealing plate; 22. Abandoned oil layer; 23. Cover plate; 24. Cable hole; 25. Positioning platform. Detailed Implementation

[0018] The embodiments of this utility model will be further described below with reference to the accompanying drawings:

[0019] Example 1:

[0020] like Figure 1 , Figure 2 As shown, the deep geothermal single-well heat exchange system in the abandoned oil well of this utility model includes a sandstone thermal reservoir 3 and a production casing 2. Several water inlet holes 4 corresponding to the sandstone thermal reservoir 3 are penetrating through the side wall of the production casing 2. A downwardly inclined branch pipe 6 is connected to the side wall of the production casing 2. The lower end of the branch pipe 6 extends into the sandstone thermal reservoir 3. An artificial well bottom 1 is sealed to the lower inner side of the production casing 2. A packer 11 located below the port of the branch pipe 6 is also connected to the inner side of the production casing 2. A booster pump 12 and a shell-and-tube heat exchanger are installed on the upper inner side of the production casing 2. A water production string 5 is connected to the inlet of the booster pump 12. The lower end of the water production string 5 penetrates the packer 11 and extends into the sandstone thermal reservoir 3. A water delivery pipe 13 is connected to the outlet of the booster pump 12. The other end of the water delivery pipe 13 is connected to the shell-and-tube heat exchanger.

[0021] During operation, hot water in the sandstone geothermal reservoir 3 enters the production casing 2 through the inlet hole 4. The artificial well bottom 1 can seal the lower end of the production casing 2 to prevent the waste oil layer 22 from contaminating the hot water in the production casing 2. The booster pump 12 is activated, causing the hot water in the production casing 2 to enter the shell-and-tube heat exchanger through the production tubing 5 and the riser pipe 13 to participate in heat exchange. The cooled geothermal water is then discharged through the shell-and-tube heat exchanger and falls onto the packer 11. It then flows back to the distant sandstone geothermal reservoir 3 along the branch pipe 6 to prevent thermal breakthrough. External water enters the shell-and-tube heat exchanger through the tube-side medium inlet 17 to participate in heat exchange. The heated external water then flows out through the tube-side medium outlet 18 and is further transported to the heat user.

[0022] Example 2:

[0023] like Figure 1 , Figure 2 As shown, based on Example 1,

[0024] Furthermore, the artificial well bottom 1 is filled with cement at the lower end of the production casing 2, which thoroughly and permanently seals the lower end of the production casing 2, effectively preventing the abandoned oil layer 22 from contaminating the sandstone thermal reservoir 3.

[0025] Furthermore, the shell-and-tube heat exchanger includes a shell 9 and a cover plate 23. The top and bottom of the shell 9 are respectively provided with an upper sealing plate 21 and a lower sealing plate 16. The cover plate 23 is connected to the port of the production layer sleeve 2. An upper tube box 20 and a sleeve 19 are fixedly connected to the bottom of the cover plate 23. The cover plate 23 has a tube-side medium inlet 17 communicating with the sleeve 19 and a tube-side medium outlet 18 communicating with the upper tube box 20. The sleeve 19 is located inside the upper tube box 20. Both the upper tube box 20 and the sleeve 19 are sealed to the upper sealing plate 21. The bottom of the lower sealing plate 16 is sealed. A lower casing box 8 is connected, and the lower casing box 8 has a shell-side medium inlet 10 and a shell-side medium outlet 7 that penetrate its body. The upper end of the shell-side medium inlet 10 penetrates the lower sealing plate 16 and extends to the lower end of the shell 9. The upper end of the shell-side medium outlet 7 penetrates the lower sealing plate 16 and extends to the upper end of the shell 9. Multiple primary heat exchange tubes 14 and multiple secondary heat exchange tubes 15 are connected between the upper sealing plate 21 and the lower sealing plate 16. Each primary heat exchange tube 14 is connected to the sleeve 19 and the lower casing box 8, and each secondary heat exchange tube 15 is connected to the upper casing box 20 and the lower casing box 8. The cover plate 23 serves as a fixing component to seal the wellhead and provides protection. During operation, hot water in the producing shell 2 enters the shell 9 through the shell-side medium inlet 10. After heat exchange within the shell 9, the hot water is discharged through the shell-side medium outlet 7 onto the packer 11, and then flows back to the distant sandstone geothermal reservoir 3 along the branch pipe 6 to prevent geothermal water loss. External cold water enters the primary heat exchange tube 14 through the tube-side medium inlet 17 and the sleeve 19, where it undergoes primary heat exchange with the hot water in the shell 9. It then flows to the lower tube box 8 and then to the secondary heat exchange tube 15, where it undergoes secondary heat exchange with the hot water in the shell 9. After secondary heating, the external water flows out through the upper tube box 20 and the tube-side medium outlet 18. The primary heat exchange tube 14 and the secondary heat exchange tube 15 are completely surrounded and covered by the heat source, resulting in a large contact area and high heat exchange efficiency. In addition, both the shell-side medium inlet 10 and the shell-side medium outlet 7 are located on the lower tube box 8, which does not occupy the installation space of the shell 9, thus maximizing the diameter of the shell 9 and improving the heat exchange effect.

[0026] Furthermore, the cover plate 23 has a through hole 24 for facilitating the wiring arrangement of the booster pump 12.

[0027] Furthermore, the top of the upper sealing plate 21 is provided with a positioning platform 25 that corresponds to and is adapted to the sleeve 19. The positioning platform 25 can effectively improve the structural strength of the sleeve 19 and effectively prevent the sleeve 19 from deforming.

[0028] It should be noted that the above description represents a preferred embodiment of this utility model and is not intended to limit its scope. This utility model is applicable not only to the renovation of abandoned oil wells but also to newly drilled deep geothermal wells. For those skilled in the art, any modifications, substitutions, or improvements made within the spirit and principles of this utility model should be included within its protection scope.

Claims

1. A deep geothermal single-well heat exchange system in an abandoned oil well, comprising a sandstone thermal reservoir (3) and a producing layer casing (2), characterized in that: The sidewall of the producing casing (2) has several inlet holes (4) corresponding to the sandstone hot reservoir (3). The sidewall of the producing casing (2) is connected to a downwardly inclined branch pipe (6). The lower end of the branch pipe (6) extends to the sandstone hot reservoir (3). The lower end of the inner side of the producing casing (2) is sealed with an artificial well bottom (1). The inner side of the producing casing (2) is also connected to a port located below the port of the branch pipe (6). The packer (11) is equipped with a booster pump (12) and a shell-and-tube heat exchanger on the upper inner side of the production casing (2). The inlet of the booster pump (12) is connected to the water production string (5). The lower end of the water production string (5) passes through the packer (11) and extends into the sandstone thermal reservoir (3). The outlet of the booster pump (12) is connected to the water supply pipe (13). The other end of the water supply pipe (13) is connected to the shell-and-tube heat exchanger.

2. The deep geothermal single-well heat exchange system in abandoned oil wells according to claim 1, characterized in that: The artificial well bottom (1) is cement filled at the lower end of the production layer casing (2).

3. The deep geothermal single-well heat exchange system in abandoned oil wells according to claim 1 or 2, characterized in that: The shell-and-tube heat exchanger includes a shell (9) and a cover plate (23). The top and bottom of the shell (9) are respectively provided with an upper sealing plate (21) and a lower sealing plate (16). The cover plate (23) is connected to the port of the production layer sleeve (2). The bottom of the cover plate (23) is fixedly connected to an upper tube box (20) and a sleeve (19). The cover plate (23) is provided with a tube-side medium inlet (17) communicating with the sleeve (19) and a tube-side medium outlet (18) communicating with the upper tube box (20). The sleeve (19) is located inside the upper tube box (20). Both the upper tube box (20) and the sleeve (19) are sealed to the upper sealing plate (21). The lower sealing plate... (16) has a bottom sealed connection to a lower tube box (8). The lower tube box (8) has a shell-side medium inlet (10) and a shell-side medium outlet (7) that penetrate its body. The upper end of the shell-side medium inlet (10) penetrates the lower sealing plate (16) and extends to the lower end of the shell (9). The upper end of the shell-side medium outlet (7) penetrates the lower sealing plate (16) and extends to the upper end of the shell (9). The upper sealing plate (21) and the lower sealing plate (16) are connected by multiple primary heat exchange tubes (14) connecting the upper sleeve (19) and the lower tube box (8) and multiple secondary heat exchange tubes (15) connecting the upper tube box (20) and the lower tube box (8).

4. The deep geothermal single-well heat exchange system in abandoned oil wells according to claim 3, characterized in that: The cover plate (23) has a through hole (24).

5. The deep geothermal single-well heat exchange system in abandoned oil wells according to claim 3, characterized in that: The top of the upper sealing plate (21) is provided with a positioning platform (25) that corresponds to and is adapted to the sleeve (19).

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