CO2 gas-tight packer

Abstract

The present invention relates to the technical field of carbon dioxide airtight seals, and is a carbon dioxide airtight seal, comprising a central tube, the upper end of which is fixedly connected to the inner side of the lower end of an upper joint, the central tube being sequentially sleeved with a piston, a sealing assembly, a guide ring, an upper cone, a slip mechanism, and a lower cone from top to bottom, the sealing assembly being capable of expansion sealing and having a hardness gradient, a locking ring sleeve being installed on the outer side of the lower end of the upper joint via a starting pin and a locking ring, the locking ring sleeve being engaged with the locking ring via teeth, and the upper end of the piston being fixedly connected to the lower end of the locking ring sleeve. The present invention has a reasonable and compact structure and is easy to use. By providing a sealing assembly with a hardness gradient, the sealing performance of the sealing assembly when squeezed and the stability of the overall structure can be ensured.

Description

Technical Field

[0001] The invention relates to the technical field of packers and relates to a carbon dioxide airtight packer. Background Art

[0002] Carbon dioxide geological storage is essentially the process of compressing carbon dioxide gas to a supercritical state and injecting it into formations deep underground with appropriate sealing conditions for long-term storage and isolation. This is used to reduce carbon dioxide emissions in the atmosphere over a period of time and slow down global warming and the deterioration of the earth's environment.

[0003] Injection and discharge wells are typically used in geological CO2 storage. Captured CO2 is injected into the formation through the injection wells, while the corresponding fluids in the formation migrate and are discharged through the discharge wells. To prevent leakage, similar to how packers are used in oil wells to isolate the production strata, geological storage also employs packers to seal the annular space between the tubing string and the wellbore, as well as between the tubing strings, thereby isolating the stored formation.

[0004] With the continuous expansion and extension of the field of oil exploration and development, the proportion of complex oil and gas reservoirs and difficult-to-use reserves is increasing. In view of the characteristics of low porosity, low permeability and extremely thick oil layers, it is necessary to consider the selection of heavy oil thermal recovery gas injection technology. It is necessary to ensure that the packer has a strong ability to resist bidirectional pressure differentials. However, the sealing components of conventional packers are not effective in high-pressure gas injection environments. The sealing components have become a shortcoming, and leakage points may exist during use due to processing problems. Summary of the Invention

[0005] The present invention provides a carbon dioxide airtight packer, which overcomes the above-mentioned deficiencies of the prior art and can effectively solve the problem that the existing packer sealing assembly has poor application effect in a high-pressure gas injection environment.

[0006] The technical solution of the present invention is achieved through the following measures: a carbon dioxide airtight seal, including a central tube, the upper end of the central tube is fixedly connected to the inner side of the lower end of the upper joint, the central tube is sequentially sleeved with a piston, a sealing assembly, a guide ring, an upper cone, a slip mechanism and a lower cone from top to bottom, the sealing assembly can expand and seal and the assembly has a hardness gradient, a locking ring sleeve is installed on the outer side of the lower end of the upper joint through a starting pin and a locking ring, the locking ring sleeve and the locking ring are matched through teeth, the upper end of the piston is fixedly connected to the lower end of the locking ring sleeve, and the center position of the upper end of the piston is fixed. A pressure transmission hole is provided on the core tube; the lower end of the guide ring is fixedly connected to the upper end of the upper cone, the slip mechanism is fixedly connected to the lower end of the upper cone through a first shear pin, the lower end of the slip mechanism is fixedly connected to the lower cone through a second shear pin, the lower end of the lower cone is fixedly connected to the upper end of the pawl sleeve, the lower end of the pawl sleeve is fixedly connected to the upper end of the lower joint, the middle part of the pawl sleeve is sleeved on the outer circle of the pawl, the upper end of the pawl is fixedly connected to the lower end of the center tube, an unsealing ring is installed at the inner circle inlet of the lower end of the pawl through an unsealing pin, and the lower end of the unsealing ring is positioned by the inner circle step of the upper end of the lower joint.

[0007] The following are further optimizations and / or improvements to the above technical solutions:

[0008] Preferably, the sealing assembly includes an upper rubber cylinder, an upper back ring, an upper support ring, an intermediate rubber cylinder, a lower support ring, a lower back ring and a lower rubber cylinder which are sequentially mounted on the center tube from top to bottom. The upper rubber cylinder, the upper back ring, the upper support ring and the lower support ring, the lower back ring and the lower rubber cylinder are symmetrically arranged on the upper and lower sides of the intermediate rubber cylinder.

[0009] Preferably, the upper rubber cylinder and the lower rubber cylinder are formed of a high-hardness hydrogenated nitrile rubber vulcanized 316L stainless steel wire mesh and a copper support ring.

[0010] Preferably, the upper back ring and the lower back ring are made of an integral die-cast aluminum bronze material, which has ductility and toughness.

[0011] Preferably, the upper support ring and the lower support ring are made of modified polytetrafluoroethylene material added with carbon brazing and graphite, and the hardness thereof is higher than that of the upper rubber cylinder, the lower rubber cylinder and the middle rubber cylinder.

[0012] Preferably, the middle rubber sleeve is made of modified hydrogenated nitrile material, with both ends vulcanized and embedded with a coil spring. The rubber hardness of the vulcanized ends is slightly higher than that of the middle rubber sleeve. The middle rubber sleeve mates with the upper and lower support rings via an inclined surface. The annular groove on the inner surface of the middle rubber sleeve serves as a preset compression compensation position, and the M-shaped ring groove on the outer surface divides the sealing surface into multiple sections. The M-shaped ring groove on the outer surface provides more uniform contact width and contact stress when in contact with the inner wall of the casing after compression.

[0013] Preferably, the cava mechanism includes a cava sleeve, a cava and a spring, the upper end of the cava sleeve is fixedly connected to the lower end of the upper cone through a first shear pin, the lower end of the cava sleeve is fixedly connected to the upper end of the lower cone through a second shear pin, and the cava and the spring are arranged between the cava sleeve and the outer wall of the center tube; or / and, the lower joint is connected to the pawl sleeve by a threaded connection and fixed by a fastening screw, the lower joint is sealed with the pawl sleeve by a sixth O-ring; the locking ring sleeve is sealed with the connecting joint by a first O-ring; the piston is sealed with the locking ring sleeve by a second O-ring, and the piston is sealed with the center tube by a third O-ring; the pawl sleeve is sealed with the pawl by a fourth O-ring; and the pawl is sealed with the center tube by a fifth O-ring.

[0014] The present invention has a reasonable and compact structure and is easy to use. By providing a sealing component with a hardness gradient, the sealing performance of the sealing component when squeezed and the stability of the overall structure can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attachment Figure 1 It is a schematic diagram of a front half-section structure of an embodiment of the present invention.

[0016] Attachment Figure 2 For attachment Figure 1 Schematic diagram of the enlarged structure of the upper part.

[0017] Attachment Figure 3 For attachment Figure 1 Schematic diagram of the enlarged structure of the lower half.

[0018] Attachment Figure 4 This is an enlarged structural diagram of the sealing component after it is rotated to the horizontal direction.

[0019] The codes in the accompanying drawings are: 1. upper connector; 2. starting pin; 3. first O-ring; 4. locking ring sleeve; 5. locking ring; 6. second O-ring; 7. piston; 8. third O-ring; 9. sealing assembly; 91. upper rubber cylinder; 92. upper back ring; 93. upper support ring; 94. middle rubber cylinder; 95. lower support ring; 96. lower back ring; 97. lower rubber cylinder; 10. center tube; 11. guide ring; 12. upper cone; 13. slip sleeve; 14. first shear pin; 15. slip; 16. spring; 17. second shear pin; 18. lower cone; 19. pawl sleeve; 20. fourth O-ring; 21. fifth O-ring; 22. pawl; 23. fastening screw; 24. sixth O-ring; 25. unsealing pin; 26. unsealing ring; 27. lower connector. DETAILED DESCRIPTION

[0020] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions.

[0021] In the present invention, for the convenience of description, the relative position relationship of each component is described based on the Figure 1 For example, the positional relationships of front, back, up, down, left, and right are determined according to the layout directions of the drawings in the specification.

[0022] The present invention will be further described below in conjunction with the embodiments and accompanying drawings:

[0023] Example 1: As shown in the attached Figure 1-4 As shown, the carbon dioxide gas-tight seal includes a central tube 10, the upper end of the central tube 10 is fixedly connected to the inner side of the lower end of the upper joint 1, and the central tube 10 is sequentially sleeved with a piston 7, a sealing assembly 9, a guide ring 11, an upper cone 12, a slip mechanism and a lower cone 18 from top to bottom. The sealing assembly 9 can expand and seal and the assembly has a hardness gradient. A locking ring sleeve 4 is installed on the outer side of the lower end of the upper joint 1 through a starting pin 2 and a locking ring 5. The locking ring sleeve 4 and the locking ring 5 are matched through teeth. The upper end of the piston 7 is fixedly connected to the lower end of the locking ring sleeve 4. A pressure transmission hole is provided on the central tube 10 at the upper end of the piston 7; the lower end of the guide ring 11 It is fixedly connected to the upper end of the upper cone 12, the slip mechanism is fixedly connected to the lower end of the upper cone 12 through the first shear pin 14, the lower end of the slip mechanism is fixedly connected to the lower cone 18 through the second shear pin 17, the lower end of the lower cone 18 is fixedly connected to the upper end of the pawl sleeve 19, the lower end of the pawl sleeve 19 is fixedly connected to the upper end of the lower joint 27, the middle part of the pawl sleeve 19 is sleeved on the outer circle of the pawl 22, the upper end of the pawl 22 is fixedly connected to the lower end of the center tube 10, and an unsealing ring 26 is installed at the inner circle inlet of the lower end of the pawl 22 through the unsealing pin 25, and the lower end of the unsealing ring 26 is positioned by the inner circle step of the upper end of the lower joint 27.

[0024] The use process of the present invention is as follows: when using the solution of the present invention, a ball seat is connected to the lower part, or the well delivery tool itself has a ball seat, a ball is dropped into the ball seat, and pump pressure is applied. The pressure pushes the piston 7 downward through the pressure transmission hole on the upper part of the central tube 10, and the piston 7 is threadedly connected to the locking ring sleeve 4. When the pressure reaches the starting pressure, the piston 7 drives the locking ring sleeve 4 to shear the starting pin 2 and continue to move downward. The piston 7 pushes the sealing assembly 9, the guide ring 11 and the upper cone 12 downward, shearing the first shear pin 14, pushing the slip mechanism to transmit force to act on the lower cone 18, shearing the second shear pin 17, and the slip mechanism expands toward the casing, biting the casing, and the sealing assembly 9 expands and seals the casing. The locking ring sleeve 4 locks the locking ring 5 under the push of the piston 7 and locks upward to prevent the sealing assembly 9 from rebounding, thus completing the setting.

[0025] Unsealing: Insert the special unsealing tool into the lower joint 27, then lift and pull the unsealing ring 26 until the unsealing pin 25 is cut off. The unsealing ring 26 moves upward to the bottom end of the milling groove of the pawl 22, driving the center tube 10 upward together. The elastic claw of the pawl 22 retracts, and the center tube 10 drives the upper joint 1 and the locking ring 5 upward until the locking ring sleeve 4 and the piston 7 are driven upward. The sealing assembly 9 rebounds and the slip mechanism retracts to complete the unsealing.

[0026] The above-mentioned carbon dioxide gas-tight packer can be further optimized and / or improved according to actual needs:

[0027] Example 2: As shown in the attached Figure 1 、 2 As shown in Figures 4 and 5, the sealing assembly 9 includes an upper rubber sleeve 91, an upper backing ring 92, an upper support ring 93, an intermediate rubber sleeve 94, a lower support ring 95, a lower backing ring 96, and a lower rubber sleeve 97, which are sequentially mounted on the center tube 10 from top to bottom. The upper rubber sleeve 91, upper backing ring 92, and upper support ring 93 are symmetrically arranged on the upper and lower sides of the intermediate rubber sleeve 94 with the lower support ring 95, lower backing ring 96, and lower rubber sleeve 97. The upper rubber sleeve 91, upper backing ring 92, and upper support ring 93 are made of different materials to form different hardness gradients. When the sealing assembly 9 is squeezed, the sealing performance of the intermediate rubber sleeve 94 after full compression and the stability of the overall structure can be maintained. The sealing assembly 9 is used in airtight environments containing high concentrations of carbon dioxide and is particularly suitable for processes such as injection of critical carbon dioxide and gas recovery in sealed layers where temperature requirements are not high.

[0028] Example 3: As shown in the attached Figure 4 As shown, the upper and lower rubber sleeves 91 and 97 are constructed using high-hardness hydrogenated nitrile rubber, vulcanized 316L stainless steel wire mesh, and a copper support ring. The internal wire mesh significantly enhances the strength, wear resistance, and fatigue resistance of the upper and lower rubber sleeves 91 and 97, while the copper support ring maintains the overall structure of the end sleeves. These sleeves provide shoulder protection, preventing collisions and premature setting during packer lowering and high-volume cycling.

[0029] Example 4: As shown in the attached Figure 4 As shown, the upper back ring 92 and the lower back ring 96 are made of an integral die-cast aluminum bronze material, which has ductility and toughness. This arrangement can prevent the end rubber tube from being excessively folded after being squeezed and deformed, and ensure that the end rubber tube and the middle rubber tube 94 expand evenly.

[0030] Example 5: As shown in the attached Figure 4As shown, the upper support ring 93 and the lower support ring 95 are made of modified polytetrafluoroethylene with carbon brazing and graphite, and their hardness is higher than that of the upper end rubber sleeve 91, the lower end rubber sleeve 97, and the middle rubber sleeve 94. The upper support ring 93 and the lower support ring 95 are made of modified polytetrafluoroethylene with carbon brazing and graphite, which has excellent corrosion resistance and temperature resistance in a carbon dioxide environment. Their hardness is higher than that of the end rubber sleeve and the middle rubber sleeve, and they play a major role in maintaining the structure of the entire sealing system and supporting the setting of the seal.

[0031] Example 6: As shown in the attached Figure 4 As shown, the middle rubber sleeve 94 is made of modified hydrogenated nitrile material, with both ends vulcanized and embedded with a coil of spring. The rubber hardness at the ends of the vulcanization is slightly higher than that of the middle rubber sleeve. The middle rubber sleeve 94 is mated to the upper support ring 93 and the lower support ring 95 via an inclined surface. The annular groove on the inner surface of the middle rubber sleeve 94 is a preset compression compensation position, and the M-shaped annular groove on the outer surface divides the sealing surface into multiple sections. A coil of spring protection structure is embedded in the vulcanized ends to maintain the balance and uniform expansion of the middle rubber sleeve 94 and provide auxiliary rebound force when the packer is released. The annular groove on the inner surface is a preset compression compensation position to prevent the middle rubber sleeve 94 from arching and becoming unstable when squeezed, or from squeezing out of the gap at the mating point with the central pipe 10. The M-shaped annular groove on the outer surface divides the sealing surface into multiple sections, making the contact width and contact stress with the inner wall of the casing more uniform after compression.

[0032] Example 7: As shown in the attached Figure 3 As shown, the slip mechanism includes a slip sleeve 13, slips 15, and a spring 16. The upper end of the slip sleeve 13 is fixedly connected to the lower end of the upper cone 12 via a first shear pin 14, and the lower end of the slip sleeve 13 is fixedly connected to the upper end of the lower cone 18 via a second shear pin 17. The slips 15 and spring 16 are disposed between the slip sleeve 13 and the outer wall of the central pipe 10. During sealing, the slips 15 are pushed, driving the slip sleeve 13 to transfer force to the lower cone 18, shearing the second shear pin 17. The slips 15 expand toward the casing, compressing the spring 16 and gripping the casing. During unsealing, the slips 15 retract, pushing the slip sleeve 13 and the upper cone 12 upward.

[0033] Example 8: As shown in the attached Figure 1-4 As shown, lower connector 27 is threadedly connected to pawl sleeve 19 and secured by setscrew 23. Lower connector 27 is sealed to pawl sleeve 19 via sixth O-ring 24. Locking ring sleeve 4 is sealed to connector 1 via first O-ring 3. Piston 7 is sealed to locking ring sleeve 4 via second O-ring 6, and to center tube 10 via third O-ring 8. Pawl sleeve 19 is sealed to pawl 22 via fourth O-ring 20. Pawl 22 is sealed to center tube 10 via fifth O-ring 21. Set screw 23 prevents the threads connecting lower connector 27 and pawl sleeve 19 from loosening, and O-rings enhance sealing, ensuring pressure retention during pump pressure sealing.

[0034] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A carbon dioxide gas-tight packer, characterized in that The cam is provided with a plurality of guide rings, a plurality of guide rings and a plurality of guide rings, and a plurality of guide rings are provided on the cam, and a plurality of guide rings are provided on the cam. The cutting pin is fixedly connected to the lower cone, and the slip mechanism includes a slip sleeve, a slip and a spring. The upper end of the slip sleeve is fixedly connected to the lower end of the upper cone through a first shear pin, and the lower end of the slip sleeve is fixedly connected to the upper end of the lower cone through a second shear pin. The slip and the spring are arranged between the slip sleeve and the outer wall of the center tube; the lower end of the lower cone is fixedly connected to the upper end of the pawl sleeve, and the lower end of the pawl sleeve is fixedly connected to the upper end of the lower joint. The middle part of the pawl sleeve is sleeved on the outer circle of the pawl, and the upper end of the pawl is fixedly connected to the lower end of the center tube. An unsealing ring is installed at the inner circle inlet of the lower end of the pawl through an unsealing pin, and the lower end of the unsealing ring is positioned by the inner circle step of the upper end of the lower joint.

2. The carbon dioxide gas-tight packer according to claim 1, characterized in that The sealing assembly includes an upper rubber cylinder, an upper back ring, an upper support ring, an intermediate rubber cylinder, a lower support ring, a lower back ring and a lower rubber cylinder which are sequentially mounted on the center tube from top to bottom. The upper rubber cylinder, the upper back ring, the upper support ring and the lower support ring, the lower back ring and the lower rubber cylinder are symmetrically arranged on the upper and lower sides of the intermediate rubber cylinder.

3. The carbon dioxide gas-tight packer according to claim 2, characterized in that The upper and lower rubber cylinders are made of high-hardness hydrogenated nitrile rubber vulcanized 316L stainless steel wire mesh and copper support ring molding structure.

4. The carbon dioxide gas-tight packer according to claim 2 or 3, characterized in that The upper and lower back rings are made of one-piece die-cast aluminum bronze material, which has ductility and toughness.

5. The carbon dioxide gas-tight packer according to claim 2 or 3, characterized in that The upper support ring and the lower support ring are made of modified polytetrafluoroethylene material added with carbon brazing and graphite, and their hardness is higher than that of the upper end rubber cylinder, the lower end rubber cylinder and the middle rubber cylinder.

6. The carbon dioxide gas-tight packer according to claim 4, characterized in that The upper support ring and the lower support ring are made of modified polytetrafluoroethylene material added with carbon brazing and graphite, and their hardness is higher than that of the upper end rubber cylinder, the lower end rubber cylinder and the middle rubber cylinder.

7. The carbon dioxide gas-tight packer according to claim 2, 3 or 6, characterized in that The middle rubber cylinder is made of modified hydrogenated nitrile material, vulcanized at both ends and embedded with a coil of spring. The rubber hardness at both ends of the vulcanization is slightly higher than the hardness in the middle. The middle rubber cylinder cooperates with the upper support ring and the lower support ring through the inclined surface. The annular groove on the inner surface of the middle rubber cylinder is the preset compression compensation position, and the M-shaped ring groove on the outer surface divides the sealing surface into multiple sections.

8. The carbon dioxide gas-tight packer according to claim 4, characterized in that The middle rubber cylinder is made of modified hydrogenated nitrile material, vulcanized at both ends and embedded with a coil of spring. The rubber hardness at both ends of the vulcanization is slightly higher than the hardness in the middle. The middle rubber cylinder cooperates with the upper support ring and the lower support ring through the inclined surface. The annular groove on the inner surface of the middle rubber cylinder is the preset compression compensation position, and the M-shaped ring groove on the outer surface divides the sealing surface into multiple sections.

9. The carbon dioxide gas-tight packer according to claim 5, characterized in that The middle rubber cylinder is made of modified hydrogenated nitrile material, vulcanized at both ends and embedded with a coil of spring. The rubber hardness at both ends of the vulcanization is slightly higher than the hardness in the middle. The middle rubber cylinder cooperates with the upper support ring and the lower support ring through the inclined surface. The annular groove on the inner surface of the middle rubber cylinder is the preset compression compensation position, and the M-shaped ring groove on the outer surface divides the sealing surface into multiple sections.

10. The carbon dioxide gas-tight packer according to claim 1, 2, 3, 6, 8 or 9, characterized in that The lower joint is connected to the pawl sleeve by threads and fixed by fastening screws. The lower joint is sealed with the pawl sleeve by the sixth O-ring; the locking ring sleeve is sealed with the connecting joint by the first O-ring; the piston is sealed with the locking ring sleeve by the second O-ring, and the piston is sealed with the center tube by the third O-ring; the pawl sleeve is sealed with the pawl by the fourth O-ring; and the pawl is sealed with the center tube by the fifth O-ring.

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