Slip packer deblocking mechanism for CO2 injection well

Abstract

The invention relates to the technical field of tertiary oil recovery, in particular to a slip packer unsealing mechanism for a CO2 injection well. The deblocking mechanism comprises an upper connector, the outer side of the upper connector is connected with a deblocking sleeve through threads, the inner side of the upper connector is connected with a deblocking seat, a sealing cavity is formed between the upper connector and the deblocking seat, the deblocking sleeve is connected with the deblocking seat through a deblocking pin, the deblocking seat is connected with a center pipe through threads, and the deblocking sleeve is connected with a limiting barrel through threads. The center pipe is arranged on the inner side of the limiting cylinder, the limiting connecting cylinder is connected to the outer side of the limiting cylinder through threads, the limiting seat is connected to the inner side of the limiting connecting cylinder, the locking block is installed on the outer side of the middle section of the center pipe, the locking block and the limiting seat can move, and the limiting seat is connected with the upper cone through threads. The slip packer unsealing mechanism for the CO2 injection well is simple and reasonable in structure, the packer can be prevented from being unsealed in advance, the unsealing force of the slip packer unsealing mechanism is small, and step-by-step unsealing of the CO2 injection well can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of tertiary oil recovery, and in particular to a slip packer unsealing mechanism for a CO2 injection well. Background Art

[0002] At present, in order to prevent the creep of the pipe string in CO2 injection wells, which may cause the packer rubber cylinder to fail to seal, slip packers are generally used to anchor the pipe string to extend the service life of the rubber cylinder. In the actual production of oil fields, especially in the process of CO2 stratified gas injection, the well completion injection pipe string generally contains multiple packers. In practical applications, when the pipe string is in the process of being lowered, the lowering of the pipe string is often accompanied by strong inertia. The inertia of the pipe string can easily cause the unsealing pin in the packer to be sheared off, causing the packer to be unsealed in advance, resulting in the failure of the packer to set. In the unsealing process of the multi-stage packer, due to the design of the structure of the packer itself, it is generally required that the multi-stage packers in the well be unsealed at the same time. If a certain level of packer cannot be unsealed for some reason, the unsealing force of the entire pipe string will increase, causing unsealing difficulties. Therefore, in view of the above shortcomings, a slip packer unsealing mechanism for CO2 injection wells is proposed. Summary of the invention

[0003] 1. Technical issues to be resolved The present invention provides a slip packer unsealing mechanism for a CO2 injection well, so as to overcome the problem that in the process of CO2 stratified gas injection, the lowering of a pipe string is accompanied by strong inertia, and the inertia of the pipe string can easily cause the unsealing pin in the packer to be sheared off, resulting in premature unsealing of the packer and causing the packer to fail to set.

[0004] (II) Technical solution In order to solve the above problems, the present invention provides a slip packer release mechanism for a CO2 injection well, comprising: An upper joint, the outer side of the upper joint is connected to an unsealing sleeve by a thread, the inner side of the upper joint is connected to an unsealing seat, a sealing chamber is provided between the upper joint and the unsealing seat, the unsealing sleeve is connected to the unsealing seat by an unsealing pin, the unsealing seat is connected to a center tube by a thread, the unsealing sleeve is connected to a limiting tube by a thread, the inner side of the limiting tube is the center tube, the outer side of the limiting tube is connected to a limiting connecting tube by a thread, the inner side of the limiting connecting tube is connected to a limiting seat, a locking block is installed on the outer side of the middle section of the center tube, the locking block and the limiting seat are both movable, and the limiting seat is connected to an upper cone by a thread.

[0005] Preferably, the outer side of the locking block is connected to a limiting cylinder, and the rear side of the locking block is connected to a limiting seat.

[0006] Preferably, the limiting cylinder limits the radial movement of the locking block, and the locking block limits the axial movement of the limiting seat.

[0007] Preferably, the central tube is provided with a groove, and a locking block is embedded in the groove of the central tube.

[0008] Preferably, the locking block is configured as a trapezoidal structure, and the angle between the trapezoid of the trapezoidal structure and the central axis is in the range of 55°-65°.

[0009] Preferably, the groove is set as a trapezoidal groove, the depth of the groove is not less than 2 mm, and the groove can match the trapezoidal structure of the locking block.

[0010] Preferably, a plurality of sealing rings are installed on the upper joint, and a plurality of sealing rings are installed on the unsealing seat.

[0011] Preferably, the rear side of the limiting cylinder is connected to a limiting seat.

[0012] Preferably, a plurality of sealing rings are installed on the limiting cylinder, and a plurality of sealing rings are installed on the limiting seat.

[0013] (III) Beneficial effects The slip packer unsealing mechanism for a CO2 injection well provided by the present invention can offset the inertia force of the tubing string through the sealing cavity formed between the upper joint and the unsealing seat during the tubing string lowering process, thereby preventing the unsealing pin from being sheared off in advance. The unsealing process of the packer is not affected by other packers, and the packer can be unsealed step by step, with a small unsealing force for the tubing string. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the installation of a slip packer release mechanism for a CO2 injection well according to an embodiment of the present invention.

[0015] Legend: 1-upper joint; 2-unsealing seat; 3-unsealing sleeve; 4-unsealing pin; 5-center tube; 6-limiting tube; 7-locking block; 8-limiting seat; 9-limiting connecting tube; 10-upper cone. Implementation

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by “upper”, “lower”, “inside”, “outside”, “top”, “bottom”, etc. are all based on the orientations or positional relationships shown in the accompanying drawings. The purpose is only to facilitate the description of the present invention and simplify the description. It does not indicate or imply that the referred parts must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] Figure 1 FIG. 1 is a schematic diagram of the installation of a slip packer release mechanism for a CO2 injection well according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a slip packer unsealing mechanism for a CO2 injection well, which specifically includes: an upper joint 1, the outer side of the upper joint 1 is connected to an unsealing sleeve 3 by a thread, the inner side of the upper joint 1 is connected to an unsealing seat 2, a sealing cavity is provided between the upper joint 1 and the unsealing seat 2, the unsealing sleeve 3 is connected to the unsealing seat 2 by an unsealing pin 4, the unsealing seat 2 is connected to a center pipe 5 by a thread, the unsealing sleeve 3 is connected to a limiting cylinder 6 by a thread, the inner side of the limiting cylinder 6 is the center pipe 5, the outer side of the limiting cylinder 6 is connected to a limiting connecting cylinder 9 by a thread, the inner side of the limiting connecting cylinder 9 is connected to a limiting seat 8, a locking block 7 is installed on the outer side of the middle section of the center pipe 5, the locking block 7 and the limiting seat 8 are both movable, and the limiting seat 8 is connected to an upper cone 10 by a thread.

[0019] In this unsealing mechanism, the outer side of the locking block 7 is connected to the limiting cylinder 6, and the rear side of the locking block 7 is connected to the limiting seat 8. The locking block 7 and the limiting seat 8 are both movable, and the limiting seat 8 has a limiting effect on the locking block 7. At the same time, the limiting cylinder 6 has a limiting effect on the locking block 7. In actual application, the limiting cylinder 6 limits the radial movement of the locking block 7, and the locking block 7 limits the axial movement of the limiting seat 8.

[0020] In actual application, the inner side of the locking block 7 is connected to the central tube 5. In the present unsealing mechanism, the central tube 5 is provided with a groove, in which the locking block 7 is embedded. The locking block 7 is set to a trapezoidal structure, and the angle between the trapezoid of the trapezoidal structure and the central axis is in the range of 55°-65°. The groove of the central tube 5 is set to a trapezoidal groove, and the depth of the groove is not less than 2 mm. The groove of the central tube 5 can cooperate with the trapezoidal structure of the locking block 7.

[0021] In this unsealing mechanism, the connection between the upper joint 1 and the unsealing seat 2 is not a threaded connection. The inner side of the upper joint 1 is connected to the unsealing seat 2. A sealing cavity is provided between the upper joint 1 and the unsealing seat 2. The sealing cavity is formed by the sealing ring of the upper joint 1 and the sealing ring of the unsealing seat 2. In actual application, multiple sealing rings are installed on the upper joint 1, and the number of sealing rings of the upper joint 1 is not less than three. Multiple sealing rings are installed on the unsealing seat 2, and the number of sealing rings of the unsealing seat 2 is not less than six.

[0022] The outer side of the limiting cylinder 6 is connected to the limiting connecting cylinder 9 by a thread, the inner side of the limiting connecting cylinder 9 is connected to the limiting seat 8, the rear side of the limiting cylinder 6 is connected to the limiting seat 8, and the limiting seat 8 is connected to the upper cone 10 by a thread. In addition, multiple sealing rings are installed on the limiting cylinder 6, and the number of sealing rings of the limiting cylinder 6 is not less than five, and multiple sealing rings are installed on the limiting seat 8, and the number of sealing rings of the limiting seat 8 is at least two.

[0023] In actual application, due to the high speed of lowering the tubing, the inertial force generated when the tubing is lowered causes the unsealing pin in the packer to be easily sheared, causing the packer to be unsealed in advance and resulting in failure of the packer to be sealed. In this unsealing mechanism, because multiple sealing rings are installed on the upper joint 1 and the unsealing seat 2, a sealing cavity is formed between the upper joint 1 and the unsealing seat 2, and the unsealing sleeve 3 and the unsealing seat 2 are fixed by the unsealing pin 4. During the process of lowering the tubing, although the tubing is lowered at a very fast speed, the tubing still has a strong downward impact force under the action of inertia. When the unsealing seat 2 moves downward and is about to shear the unsealing pin 4, as the moving distance of the unsealing seat 2 increases, the volume of the sealing cavity will also expand accordingly, and an upward negative pressure will be formed inside the sealing cavity, effectively preventing the unsealing pin 4 from being sheared in advance.

[0024] In this unsealing mechanism, when the inner tube of the packer is pressurized and sealed, the upper end face of the center tube 5 is supported on the upper joint 1, and the locking block 7 is stably embedded in the groove of the center tube 5 through the limiting action of the limiting seat 8. The upper cone 10 is connected to the limiting seat 8 by a threaded connection. When the rubber cylinder of the packer is compressed and expanded upward, the slip of the packer is also squeezed. The slip of the packer is extended along the conical surface of the upper cone 10, so as to complete the anchoring of the packer.

[0025] In addition, in practical applications, the trapezoidal structure of the locking block 7 can be fully matched with the trapezoidal groove of the central tube 5, and the limiting tube 6 can limit the radial movement of the locking block 7. When the rubber tube of the packer is under downward pressure, the upward force generated by it can be transmitted to the locking block 7 and the central tube 5. Because the unsealing pin 4 is not subjected to any force, the unsealing pin 4 can further achieve the purpose of preventing upward pushing. Since the upper joint 1 is connected to the unsealing sleeve 3 by thread, the unsealing sleeve 3 is connected to the limiting tube 6 by thread, and the limiting tube 6 is connected to the limiting connecting tube 9 by thread, the limiting The connecting tube 9 is connected to the limit seat 8. Therefore, when the tubing is lifted up from the wellhead, the tubing can drive the upper joint 1 upward, and the upper joint 1 can drive the unsealing sleeve 3 upward. The unsealing sleeve 3 moves upward to cut off the unsealing pin 4, and the unsealing sleeve 3 can drive the limit tube 6 upward. The limit tube 6 moves upward to make room, and the limit connecting tube 9 continues to move upward, and the limit connecting tube 9 continues to pull the limit seat 8 upward. When the limit seat 8 is lifted up to unseal, the locking block 7 can come out of the groove of the central pipe 5 without any constraint, so that the packer can be unsealed.

[0026] The following describes the working principle of the slip packer release mechanism for CO2 injection wells: In this embodiment, the outer side of the upper joint 1 is threadedly connected to the unsealing sleeve 3, and the inner side of the upper joint 1 is connected to the unsealing seat 2. A sealing chamber is provided between the upper joint 1 and the unsealing seat 2. The unsealing seat 2 and the unsealing sleeve 3 are fixed by an unsealing pin 4. The unsealing seat 2 is threadedly connected to the center tube 5. The center tube 5 is provided with a groove. The groove of the center tube 5 is embedded in the locking block 7. The rear side of the locking block 7 is a limiting seat 8. The outer side of the locking block 7 is a limiting tube 6. The limiting tube 6 is threadedly connected to the unsealing sleeve 3. The outer side of the limiting tube 6 is threadedly connected to the limiting connecting tube 9. The rear side of the limiting tube 6 is connected to the limiting seat 8. The inner side of the limiting connecting tube 9 is connected to the limiting seat 8. The limiting seat 8 is threadedly connected to the upper cone 10.

[0027] In actual application, the groove of the center tube 5 is a trapezoidal groove with a depth of 2 mm. The locking block 7 is a trapezoidal structure with an angle range of 60° with the central axis. The trapezoidal structure of the locking block 7 can cooperate with the groove of the center tube 2. In addition, because the locking block 7 and the limit seat 8 can both move, the limit seat 8 has a limiting effect on the locking block 7, and the limiting cylinder 6 has a limiting effect on the locking block 7. The limiting cylinder 6 limits the radial movement of the locking block 7, and the locking block 7 limits the axial movement of the limit seat 8.

[0028] In this embodiment, the upper joint 1 and the unsealing seat 2 are not threadedly connected, and the upper joint 1 and the unsealing seat 2 can cooperate to form a sealed cavity through multiple sealing rings installed thereon. In actual applications, when the pipe string is lowered, generally speaking, the pipe string is lowered very quickly. Due to the high lowering speed of the pipe string, the pipe string has a downward impact force under the action of inertia, and the downward movement of the unsealing seat 2 is very likely to cause the unsealing pin 4 to be sheared. However, in actual applications, due to the increase in the gap between the upper joint 1 and the unsealing seat 2, the volume of the sealed cavity is further expanded, and an upward negative pressure is formed inside the sealed cavity, further preventing the unsealing pin 4 from being sheared off prematurely.

[0029] In actual applications, since the locking block 7 adopts a trapezoidal structure with an angle of 60° with the central axis, the locking block 7 and the center tube 5 can form a fit. In this embodiment, the limit cylinder 6 limits the radial movement of the locking block 7. When the rubber tube of the packer is under pressure, the upward force it exerts can be transmitted to the locking block 7 and the center tube 5. Since the unsealing pin 4 is not affected by any force, the unsealing pin 4 effectively plays the role of preventing upward pushing. When the limit seat 8 is lifted up to unseal, it is convenient for the locking block 7 to come out of the groove, thereby realizing the unsealing of the packer.

[0030] In this embodiment, when the inner tube of the packer is pressurized and sealed, the upper end face of the center tube 5 is supported on the upper joint 1, the locking block 7 is embedded in the groove of the center tube 5, and the upper cone 10 is connected to the limit seat 8 through a thread. When the rubber cylinder of the packer is compressed and expanded upward, the packer's slips are also squeezed at the same time. The packer's slips are extended along the conical surface of the upper cone 10, thereby completing the anchoring of the packer.

[0031] This unsealing mechanism can be used not only for unsealing a single-stage packer, but also for unsealing a multi-stage packer. The following is a detailed description of the implementation method of the unsealing mechanism based on the slip packer for CO2 injection wells: Step 1: The pipe string is lifted from the wellhead, and the pipe string drives the upper joint 1 upward, and the upper joint 1 drives the unsealing sleeve 3 to continue to move upward. After the unsealing sleeve 3 moves upward, the unsealing pin 4 is cut off; Step 2: The unsealing sleeve 3 drives the limiting cylinder 6 upward, the limiting cylinder 6 makes room, and the limiting cylinder 6 drives the limiting connecting cylinder 9 upward; Step 3: The limiting connecting tube 9 pulls the limiting seat 8 upward, the locking block 7 is disengaged from the groove of the central tube 5, and the upper cone 10 moves upward, completing the unsealing of the packer slips and the rubber cylinder; Step 4: Continue to lift the tubing string to release the second, third, and fourth level packers.

[0032] The slip packer unsealing mechanism for a CO2 injection well provided by the present invention can offset the inertia force of the tubing string through the sealing cavity formed between the upper joint and the unsealing seat during the tubing string lowering process, thereby preventing the unsealing pin from being sheared off in advance. The unsealing process of the packer is not affected by other packers, and the packer can be unsealed step by step, with a small unsealing force for the tubing string.

[0033] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A slip packer release mechanism for a CO2 injection well, characterized in that: include: An upper joint (1), wherein the outer side of the upper joint (1) is connected to an unsealing sleeve (3) by means of a thread, the inner side of the upper joint (1) is connected to an unsealing seat (2), a sealing chamber is provided between the upper joint (1) and the unsealing seat (2), the unsealing sleeve (3) is connected to the unsealing seat (2) by means of an unsealing pin (4), the unsealing seat (2) is connected to a center tube (5) by means of a thread, the unsealing sleeve (3) is connected to a limiting tube (6) by means of a thread, the inner side of the limiting tube (6) is the center tube (5), the outer side of the limiting tube (6) is connected to a limiting connecting tube (9) by means of a thread, the inner side of the limiting connecting tube (9) is connected to a limiting seat (8), a locking block (7) is installed on the outer side of the middle section of the center tube (5), the locking block (7) and the limiting seat (8) are both movable, and the limiting seat (8) is connected to an upper cone (10) by means of a thread.

2. The slip packer release mechanism for a CO2 injection well according to claim 1, characterized in that: The outer side of the locking block (7) is connected to the limiting cylinder (6), and the rear side of the locking block (7) is connected to the limiting seat (8).

3. The slip packer release mechanism for a CO2 injection well according to claim 2, characterized in that: The limiting cylinder (6) limits the radial movement of the locking block (7), and the locking block limits the axial movement of the limiting seat.

4. The slip packer release mechanism for a CO2 injection well according to claim 1, characterized in that: The central tube (5) is provided with a groove, and a locking block (7) is embedded in the groove of the central tube (5).

5. The slip packer release mechanism for a CO2 injection well according to claim 4, characterized in that: The locking block (7) is configured as a trapezoidal structure, and the angle between the trapezoidal structure and the central axis is in the range of 55°-65°.

6. The slip packer release mechanism for a CO2 injection well according to claim 4, characterized in that: The groove is configured as a trapezoidal groove, the depth of the groove is not less than 2 mm, and the groove can match the trapezoidal structure of the locking block (7).

7. The slip packer release mechanism for a CO2 injection well according to claim 6, characterized in that: A plurality of sealing rings are installed on the upper joint (1), and a plurality of sealing rings are installed on the unsealing seat (2).

8. The slip packer release mechanism for a CO2 injection well according to claim 1, characterized in that: The rear side of the limiting cylinder (6) is connected to the limiting seat (8).

9. The slip packer release mechanism for a CO2 injection well according to claim 8, characterized in that: A plurality of sealing rings are installed on the limiting cylinder (6), and a plurality of sealing rings are installed on the limiting seat (8).

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