Horizontal well carbon dioxide separate layer gas injection pipe string

Abstract

The application discloses a horizontal well carbon dioxide layered gas injection pipe column, which comprises a pipe column body, a tubing arranged in the pipe column body, a plurality of packers and a plurality of electrically-controlled gas injection sliding sleeves; the pipe column body is divided into a vertical section and a horizontal section; in the horizontal section, the direction close to the vertical section is front, and the direction far from the vertical section is back; the horizontal section comprises a plurality of horizontal regions, each of which is provided with one packer located in front and one electrically-controlled gas injection sliding sleeve located in back; the tubing is connected head to tail between the center channels of the adjacent packers and electrically-controlled gas injection sliding sleeves, and the tubing at the front end extends to the vertical section; the tubing is opened at the top end of the vertical section as an inlet; the side surface of each electrically-controlled gas injection sliding sleeve is provided with a signal receiver and an openable and closable gas injection channel, and each electrically-controlled gas injection sliding sleeve is provided with a corresponding signal ball; the signal receiver is used for sensing the signal ball; by throwing the signal ball from the inlet, the gas injection channel of the corresponding electrically-controlled gas injection sliding sleeve can be opened or closed.

Description

Technical Field

[0001] This invention relates to the field of gas injection tubing technology, and in particular to a horizontal well carbon dioxide stratified gas injection tubing. Background Technology

[0002] In carbon dioxide huff and puff or oil displacement operations, staged gas injection is an effective means of improving oil recovery. Currently, in vertical or highly deviated wells, to achieve staged gas injection, a ball is typically dropped to open the sliding sleeve, and after injection, the packer is directly pulled up to retrieve the tubing. However, in horizontal wells, if a similar approach is used, for multiple packers connected in series, unsealing by pulling up is difficult due to the excessive unsealing tonnage and torque transmission issues in horizontal wells. Furthermore, the opening and closing of conventional ball-dropped sliding sleeves is limited by the ball's grading, which cannot meet the requirements for finely stratified gas injection exceeding three stages. Summary of the Invention

[0003] The purpose of this invention is to provide a horizontal well carbon dioxide stratified gas injection string to solve the technical problems existing in the background art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A horizontal well carbon dioxide stratified gas injection string includes a string body, an oil pipe disposed inside the string body, multiple packers, and multiple electrically controlled gas injection sleeves; The tubular column is divided into a vertical section and a horizontal section; In the horizontal section, the direction closer to the vertical section is considered the front, and the opposite direction is considered the rear. The horizontal section includes multiple horizontal areas, and each horizontal area is provided with a packer located in front and an electrically controlled gas injection sleeve located in the rear. The central channels of adjacent packers and electrically controlled gas injection sleeves are connected end to end by oil pipes, and the foremost oil pipe extends to the vertical section, with the oil pipe opening at the top of the vertical section as an inlet. Each of the electrically controlled gas injection sleeves is provided with a signal receiver and an openable and closable gas injection channel on its side, and each of the electrically controlled gas injection sleeves is equipped with a corresponding signal ball, and the signal receiver is used to sense the corresponding signal ball. This allows the gas injection channel of the corresponding electrically controlled gas injection sleeve to be opened or closed by throwing a signal ball from the inlet.

[0005] In some embodiments, the electronically controlled air injection sleeve further includes an outer cylinder sleeve and a motor, a reducer, an output rod, and an inner sleeve installed inside the outer cylinder sleeve; The motor is used to drive the output rod to rotate via a reducer. The output rod is located inside the inner sleeve and is threadedly engaged with the inner sleeve, so that the rotation of the output rod can drive the inner sleeve to slide relative to the outer cylinder sleeve. Furthermore, both the inner sliding sleeve and the outer cylinder sleeve are provided with air injection holes. When the positions of the air injection holes on the inner sliding sleeve and the outer cylinder sleeve correspond, the air injection channel is opened.

[0006] In some embodiments, each packer includes a ball seat, and all packers are capable of engaging a release ball such that after the release ball is thrown from the entrance, the release ball initially remains at the ball seat, and pressure applied at the entrance can control the release ball to pass through the ball seat and release the corresponding packer.

[0007] In some embodiments, the inner wall of each packer is further provided with a limiting groove corresponding to the ball seat. When the unsealing ball is stopped at the ball seat, by pressing at the entrance, the ball seat can be pushed to the position of the limiting groove, so that the unsealing ball can pass through the ball seat.

[0008] In some embodiments, the signal ball is smaller than the unsealing ball, allowing the signal ball to pass through the central channel between the packer and the electrically controlled gas injection sleeve.

[0009] In some embodiments, a tubing expansion joint is provided in the vertical section of the tubing string.

[0010] Another aspect of the present invention provides a method for stratified carbon dioxide injection in horizontal wells, employing the aforementioned horizontal well stratified carbon dioxide injection tubing, and comprising the following steps: S1. After completing the preparation work, send the horizontal well carbon dioxide stratified gas injection string into the preset position of the horizontal well. The number of packers and electrically controlled gas injection sleeves is represented by n, and they are arranged in order from front to back. S2. Pressurize from the inlet until the setting pressure is reached to set all packers; S3. The first signal ball is sent from the inlet using a continuous tubing. This signal ball is used to control the opening of the air injection channel of the last electrically controlled air injection sleeve. S4. Remove the coiled tubing and inject carbon dioxide until the preset requirements are met; S5. Insert the i-th signal ball from the entrance, i≥2. This signal ball is used to control the opening of the gas injection channel of the i-th to last electrically controlled gas injection sleeve and to control the closing of the gas injection channel of the (i-1)-th to last electrically controlled gas injection sleeve. S6. Inject carbon dioxide until the preset requirements are met; S7. Repeat steps S5-S6 several times until the first electrically controlled gas injection sleeve opens and carbon dioxide injection is completed. S8. When it is necessary to remove the tubing, drop the unsealing ball and pressurize from the inlet to unseal the first to the nth packers in sequence; S9. After all packers have been released, lift the tube string directly.

[0011] In some embodiments, the preparation work in step S1 includes: Determine the location of the stratified gas injection in the horizontal well, as well as the gas injection volume and duration for each stratification; Complete the flushing and scraping of the horizontal well.

[0012] Compared with the prior art, the advantages of the present invention are as follows: The present invention provides a horizontal well carbon dioxide stratified gas injection string and injection method. By using multiple packers spaced apart and electrically controlled gas injection sleeves, it ensures that only the necessary electrically controlled gas injection sleeves are opened during gas injection, while the remaining electrically controlled gas injection sleeves remain closed and unaffected. At the same time, the packers ensure effective isolation, realizing stratified carbon dioxide injection in horizontal wells. Furthermore, after stratified gas injection is completed, this structure can release all packers by a single deployment of a release ball combined with pressure testing at the inlet, solving the problem of difficulty in releasing multiple packers in horizontal wells. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the description of the embodiment will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A schematic diagram of a horizontal well carbon dioxide stratified gas injection string provided for this invention; Figure 2 This is a schematic diagram of the electrically controlled air injection sliding sleeve in an embodiment of the present invention; Figure 3 This is a partial structural schematic diagram of the packer in an embodiment of the present invention.

[0015] Explanation of reference numerals in the attached diagram: 1. Packer; 2. Electrically controlled air injection sleeve; 3. Pipeline body; 4. Oil pipe; 5. Oil pipe expansion joint; 6. Unsealing ball; 7. Guide shoe; 11. Ball seat; 12. Limiting groove; 21. Signal receiver; 22. Outer cylinder liner; 23. Motor; 24. Reducer; 25. Output rod; 26. Inner sleeve; 27. Air injection port. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0018] In one specific embodiment, refer to Figure 1 As shown, this invention provides a horizontal well carbon dioxide stratified injection tubing string, including a tubing body 3 and an oil tubing 4 disposed inside the tubing body 3, multiple packers 1, and multiple electrically controlled injection sleeves 2; the tubing body 3 is divided into a vertical section and a horizontal section; in the horizontal section, the direction closest to the vertical section is considered forward (corresponding to...). Figure 1 The left side of the middle, and the opposite is the back side (corresponding to the left side). Figure 1 (Right side of the middle), the horizontal section includes multiple horizontal areas, each of which is equipped with a packer 1 located in front and an electrically controlled gas injection sleeve 2 located behind; the central channels of adjacent packers 1 and electrically controlled gas injection sleeve 2 are connected end to end by oil pipes 4, and the oil pipe 4 at the front extends to the vertical section, with the oil pipe 4 opening at the top of the vertical section as an inlet.

[0019] Further reference Figure 2 As shown, each electrically controlled gas injection slide sleeve 2 is provided with a signal receiver 21 and an openable and closable gas injection channel on its side, and each electrically controlled gas injection slide sleeve 2 is equipped with a corresponding signal ball. The signal receiver 21 is used to sense the corresponding signal ball, so that by throwing the signal ball from the inlet, the gas injection channel of the corresponding electrically controlled gas injection slide sleeve 2 can be opened or closed.

[0020] Preferably, a tubing expansion joint 5 is installed in the vertical section of the tubing string to compensate for the shrinkage of the tubing 4 caused by the low temperature during carbon dioxide injection, thus solving the problem of tubing string shrinkage due to temperature. In addition, a guide shoe 7 is provided at the end of the tubing string 3.

[0021] Understandable Figure 1 The diagram only briefly shows the placement of different structures within the tubing body 3. The packer 1, electrically controlled air injection sleeve 2, tubing expansion joint 5, and guide shoe 7, represented in simplified diagrams, do not reflect structural details. The structural details of the electrically controlled air injection sleeve 2 are as follows: Figure 2 As shown, some structural details of packer 1 are as follows: Figure 1 As shown, the oil pipe expansion joint 5 and the guide shoe 7 can be existing products. Figure 1 The image shows the situation where the air injection channel of the rightmost electrically controlled air injection sleeve 2 is open, while the air injection channels of the other electrically controlled air injection sleeves 2 are closed.

[0022] Preferably, the electronically controlled air injection sleeve 2 further includes an outer cylinder sleeve 22 and a motor 23, a reducer 24, an output rod 25, and an inner sleeve 26 installed inside the outer cylinder sleeve 22; the motor 23 is used to drive the output rod 25 to rotate through the reducer 24, the output rod 25 is located inside the inner sleeve 26 and is threadedly engaged with the inner sleeve 26, so that the rotation of the output rod 25 can drive the inner sleeve 26 to slide relative to the outer cylinder sleeve; and both the inner sleeve 26 and the outer cylinder sleeve 22 are provided with air injection holes 27, and when the positions of the air injection holes 27 on the inner sleeve 26 and the outer cylinder sleeve 22 correspond, the air injection channel is opened.

[0023] It is understandable that the scheme of controlling the electrically controlled sliding sleeve through a signal ball is already used in existing technology, and the cooperation between the electrically controlled air-injection sliding sleeve 2 and the signal ball can be achieved using existing electrical control principles. When the signal ball moves inside the electrically controlled air-injection sliding sleeve 2, the signal receiver 21 detects the information emitted by the signal ball. If it matches the electrically controlled air-injection sliding sleeve 2, it controls the motor 23 to rotate forward or backward according to the corresponding information, thereby controlling the opening or closing of the air injection channel.

[0024] Further reference Figure 3 As shown, preferably, each packer 1 includes a ball seat 11, and all packers 1 can cooperate with a release ball 6, so that after the release ball 6 is thrown from the inlet, the release ball 6 can initially stay at the ball seat 11, and by pressurizing at the inlet (pressurization can be achieved by existing pump trucks or other equipment), the release ball 6 can be controlled to pass through the ball seat 11 and release the corresponding packer 1. The inner wall of each packer 1 is also provided with a limiting groove 12 corresponding to the ball seat 11. When the release ball 6 stays at the ball seat 11, by pressurizing at the inlet, the ball seat 11 can be pushed to the position of the limiting groove 12, so that the release ball 6 can pass through the ball seat 11.

[0025] Understandable Figure 3 Only the portion of packer 1 near ball seat 11 is shown; the rest is similar to existing gas-filled packers with drop-and-release mechanisms, including a rubber sleeve and slips. Before gas injection, pressurization at the inlet opens the rubber sleeve of packer 1, achieving a settling seal and effectively isolating different gas-filled layers during injection. After injection, the release ball 6 (which can be a steel ball) is dropped. The release ball first rests on ball seat 11 of the foremost packer 1. Pressurization at this point causes a rapid increase in internal pressure, pushing the head of ball seat 11 to the position of the limiting groove 12. The ball then automatically opens under elasticity, allowing it to pass through the ball seat 11 and release the packer 1. A decrease in internal pressure indicates that the packer 1 has been released. The steel ball then moves to the ball seat 11 of the next packer 1, and pressurization again releases it, and so on. All packers 1 can be released with a single drop. After releasing all packers 1, the ejector string can be lifted directly.

[0026] Understandably, the signal ball is smaller than the unsealing ball 6, allowing the signal ball to pass through the central channel between the packer 1 and the electrically controlled gas injection sleeve 2.

[0027] Another aspect of the present invention provides a method for stratified carbon dioxide injection in horizontal wells, employing the aforementioned horizontal well stratified carbon dioxide injection tubing, and comprising the following steps: S1. Complete the preparatory work, including: selecting the horizontal well to be injected with gas, selecting the carbon dioxide injection zone in the horizontal well, determining the stratified injection location of the horizontal well, and the injection volume and injection duration of each layer; and completing the flushing and scraping of the horizontal well.

[0028] In this embodiment, the horizontal well is required to be flushed down to the bottom of the artificial well to ensure that the color of the effluent after flushing is consistent with that of the influent; during the scraping of the horizontal well, the entire wellbore is scraped to ensure that there are no sharp burrs on the wellbore.

[0029] After completing the preparation work, the horizontal well carbon dioxide stratified gas injection string is sent into the preset position of the horizontal well. The number of packers 1 and electrically controlled gas injection sleeves 2 is represented by n. Figure 1 In the example shown, n=4), and they are sorted in order from front to back (i.e. Figure 1 The left end is the first packer 1 and the electrically controlled gas injection sleeve 2, and the right end is the fourth packer 1 and the electrically controlled gas injection sleeve 2.

[0030] S2. Pressurize from the inlet until the setting pressure is reached to set all packers 1.

[0031] S3. The first signal ball is sent from the inlet using a continuous tubing. This signal ball is used to control the opening of the air injection channel of the last electrically controlled air injection sleeve 2. Figure 1 The diagram shows the situation where the air injection channel of the last electrically controlled air injection sleeve 2 is open, while the air injection channels of the other electrically controlled air injection sleeves 2 are closed. Because there may be blockage inside the tubing, the first signal ball may be difficult to directly deliver to the required position by ball throwing. Therefore, it is assisted by continuous tubing to simultaneously resolve the internal blockage problem, allowing subsequent signal balls to be directly delivered by ball throwing.

[0032] S4. Remove the coiled tubing and inject carbon dioxide until the preset requirements are met.

[0033] S5. Insert the i-th signal ball from the entrance, i≥2. This signal ball is used to control the opening of the gas injection channel of the i-th to last electrically controlled gas injection slide sleeve 2 and to control the closing of the gas injection channel of the (i-1)-th to last electrically controlled gas injection slide sleeve 2.

[0034] S6. Inject carbon dioxide until the preset requirements are met.

[0035] S7. Repeat steps S5-S6 several times until the first electrically controlled gas injection sleeve 2 is opened and carbon dioxide injection is completed.

[0036] S8. Depending on actual needs, the well can be shut down for a period of time. When the tubing needs to be pulled out, the unsealing ball 6 is dropped and pressure is applied from the inlet to unseal the first to the nth packer 1 in sequence.

[0037] S9. After all packers have been released, lift the tube string directly.

[0038] In summary, the horizontal well carbon dioxide stratified injection tubing and injection method provided by this invention, through multiple packers spaced apart and electrically controlled injection sleeves, ensures that only the necessary electrically controlled injection sleeves are opened during injection, while the remaining electrically controlled injection sleeves remain closed and unaffected. Simultaneously, the packers ensure effective isolation, achieving stratified carbon dioxide injection in horizontal wells. Furthermore, after stratified injection is completed, this structure can release all packers with a single release ball deployment combined with inlet pressure testing, solving the problem of difficulty in releasing multiple packers in horizontal wells.

[0039] Finally, it should be noted that the above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A horizontal well carbon dioxide stratified gas injection string, characterized in that, Includes a tubing body (3) and an oil pipe (4) disposed inside the tubing body (3), multiple packers (1) and multiple electrically controlled gas injection sleeves (2); The tubular body (3) is divided into a vertical section and a horizontal section; In the horizontal section, the direction closer to the vertical section is the front and the opposite direction is the rear. The horizontal section includes multiple horizontal areas, and each horizontal area is provided with a packer (1) located in front and an electrically controlled gas injection sleeve (2) located in the rear. The central channels of adjacent packers (1) and electrically controlled air-injection sleeves (2) are connected end to end by oil pipes (4), and the oil pipe (4) at the front end extends to the vertical section, with the oil pipe (4) opening at the top of the vertical section as an inlet. Each of the electrically controlled gas injection sleeves (2) is provided with a signal receiver (21) and an openable and closable gas injection channel on its side, and each of the electrically controlled gas injection sleeves (2) is provided with a corresponding signal ball, and the signal receiver (21) is used to sense the corresponding signal ball. This allows the gas injection channel of the corresponding electrically controlled gas injection sleeve (2) to be opened or closed by throwing a signal ball from the inlet.

2. The horizontal well carbon dioxide stratified gas injection string according to claim 1, characterized in that, The electronically controlled air injection sleeve (2) also includes an outer cylinder sleeve (22) and a motor (23), a reducer (24), an output rod (25) and an inner sleeve (26) installed inside the outer cylinder sleeve (22). The motor (23) is used to drive the output rod (25) to rotate through the reducer (24). The output rod (25) is located inside the inner sleeve (26) and is threadedly engaged with the inner sleeve (26), so that the rotation of the output rod (25) can drive the inner sleeve (26) to slide relative to the outer cylinder sleeve. Furthermore, both the inner sliding sleeve (26) and the outer cylinder sleeve (22) are provided with air injection holes (27). When the positions of the air injection holes (27) on the inner sliding sleeve (26) and the outer cylinder sleeve (22) correspond, the air injection channel is opened.

3. The horizontal well carbon dioxide stratified gas injection string according to claim 1, characterized in that, Each of the packers (1) includes a ball seat (11), and all packers (1) can cooperate with an unsealing ball (6) such that after the unsealing ball (6) is thrown from the entrance, the unsealing ball (6) can initially stay at the ball seat (11), and the unsealing ball (6) can be controlled to pass through the ball seat (11) and unseal the corresponding packer (1) by pressing at the entrance.

4. The horizontal well carbon dioxide stratified gas injection string according to claim 3, characterized in that, Each packer (1) is also provided with a limiting groove (12) corresponding to the ball seat (11) on its inner wall. When the unsealing ball (6) is stopped at the ball seat (11), the ball seat (11) can be pushed to the position of the limiting groove (12) by pressing at the entrance, so that the unsealing ball (6) can pass through the ball seat (11).

5. The horizontal well carbon dioxide stratified gas injection string according to claim 4, characterized in that, The signal ball is smaller than the unsealing ball (6), so that the signal ball can pass through the central channel between the packer (1) and the electrically controlled gas injection sleeve (2).

6. The horizontal well carbon dioxide stratified gas injection string according to claim 1, characterized in that, A tubing expansion joint (5) is installed in the vertical section of the tubing string.

7. A method for stratified carbon dioxide injection in horizontal wells, characterized in that, The method employs the horizontal well carbon dioxide stratified gas injection string according to any one of claims 1-6, and includes the following steps: S1. After completing the preparation work, send the horizontal well carbon dioxide layered gas injection tubing into the preset position of the horizontal well. The number of packers (1) and electrically controlled gas injection sleeves (2) is represented by n and arranged in order from front to back. S2. Pressurize from the inlet until the setting pressure is reached to set all packers (1). S3. The first signal ball is sent from the inlet using a continuous tubing. This signal ball is used to control the opening of the gas injection channel of the last electrically controlled gas injection sleeve (2). S4. Remove the coiled tubing and inject carbon dioxide until the preset requirements are met; S5. The i-th signal ball is inserted from the entrance, i≥2. The signal ball is used to control the opening of the gas injection channel of the i-th to last electrically controlled gas injection slide (2) and to control the closing of the gas injection channel of the (i-1)-th to last electrically controlled gas injection slide (2). S6. Inject carbon dioxide until the preset requirements are met; S7. Repeat steps S5-S6 several times until the first electrically controlled gas injection sleeve (2) is opened and carbon dioxide injection is completed. S8. When the tubing needs to be removed, drop the unsealing ball (6) and pressurize from the inlet to unseal the first to the nth packer (1) in sequence. S9. After all packers have been released, lift the tube string directly.

8. The horizontal well carbon dioxide stratified gas injection method according to claim 7, characterized in that, In step S1, the preparation work includes: Determine the location of the stratified gas injection in the horizontal well, as well as the gas injection volume and duration for each stratification; Complete the flushing and scraping of the horizontal well.

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