Thermal recovery packer

Abstract

The utility model discloses a thermal recovery packer which comprises an upper connector, a lower connector, an adjusting cap, a lower protective cap, an outer sleeve, a lock spring outer sleeve and a compression type combined rubber sleeve, the outer sleeve is composed of an outer sleeve body and a sealing end, the sealing end is in threaded connection with the lower protective cap, and the inner wall of the sealing end is in sliding sealing fit with the outer wall of the lower connector. An annular hydraulic cylinder is formed between the inner wall of the outer sleeve and the outer wall of the lower connector, an annular setting piston is installed in the hydraulic cylinder, the lower end of the lock spring outer sleeve is inserted into the hydraulic cylinder and connected with the setting piston, and the hydraulic cylinder between the annular piston and the sealing end is filled with thermal expansion media. A lock spring embedding ring groove is formed in the outer wall of the lower connector, a lock spring is arranged in the lock spring embedding ring groove, and a one-way gear ring matched with lock teeth of the lock spring is arranged on the inner wall of the lock spring outer sleeve. The packer can keep stable sealing performance in a high-temperature and high-pressure environment and is provided with a reliable one-way locking mechanism, and it is ensured that the packer cannot lose efficacy in thermal recovery operation.

Description

Technical Field

[0001] This utility model relates to a packer used in oilfield downholes, and more particularly to a thermal recovery packer used to seal the annular space between the tubing and casing during thermal recovery operations. Background Art

[0002] In oilfield thermal recovery operations, packers are crucial tools for sealing the annular space between the tubing and casing. Current thermal recovery packers typically employ hydraulic or mechanical methods for setting, but under high temperature and pressure conditions, the sealing performance and stability of the packers are often difficult to guarantee. Especially during thermal recovery, the packer must withstand the combined effects of high temperature and high pressure, which can easily lead to seal failure or packer damage. Furthermore, the locking mechanisms of existing packers are prone to failure under high temperature conditions, preventing the packer from maintaining a stable setting state. Therefore, there is an urgent need for a thermal recovery packer that can maintain good sealing performance and stability under high temperature and high pressure conditions. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a thermal recovery packer that can maintain stable sealing performance under high temperature and high pressure environment and has a reliable one-way locking mechanism to ensure that the packer will not fail during thermal recovery operations.

[0004] The technical solution adopted to solve the technical problem is as follows: A thermal recovery packer includes an upper connector and a lower connector connected together by threads. An adjusting cap is installed on the upper connector. The lower connector is a tubular lower connector with a stepped cylindrical surface. A lower protective cap, an outer sleeve, a locking spring outer sleeve, and a compression-type combined rubber sleeve are sequentially installed on the outer wall of the lower connector. The outer sleeve is composed of an outer sleeve body and a sealing end at the lower end of the outer sleeve body. The sealing end is threadedly connected to the lower protective cap. The inner wall of the sealing end is in sliding sealing fit with the outer wall of the lower connector, thereby forming an annular hydraulic cylinder between the inner wall of the outer sleeve body and the outer wall of the lower connector. An annular setting piston is installed in the hydraulic cylinder. The lower end of the locking spring outer sleeve is inserted into the hydraulic cylinder and connected to the setting piston. The hydraulic cylinder between the annular piston and the sealing end is filled with a thermal expansion medium. A locking spring embedding annular groove is opened on the outer wall of the lower connector. A locking spring is installed in the locking spring embedding annular groove. A one-way toothed ring that engages with the locking teeth of the locking spring is provided on the inner wall of the locking spring outer sleeve.

[0005] As a further improvement of this utility model: an O-ring sealing ring groove and a composite sealing ring groove are provided on the inner wall of the annular piston, and an O-ring and a polytetrafluoroethylene inner retaining ring are embedded in the composite sealing ring groove.

[0006] As a further improvement of this utility model: an O-ring sealing ring groove and a composite sealing ring groove are provided on the outer wall of the annular piston, and an O-ring and a polytetrafluoroethylene outer retaining ring are embedded in the composite sealing ring groove.

[0007] As a further improvement of this utility model, two composite sealing ring grooves are provided on the inner and outer walls of the annular piston.

[0008] As a further improvement of this utility model: the locking spring is a C-shaped open elastic metal locking spring.

[0009] As a further improvement of this utility model: the upper end of the locking spring jacket is fixed to the outer wall of the lower connector by a seat seal scissor.

[0010] As a further improvement of this utility model: an O-ring sealing ring groove and a composite sealing ring groove are opened on the inner wall of the sealing end, and an O-ring and a polytetrafluoroethylene inner retaining ring are embedded in the composite sealing ring groove.

[0011] As a further improvement of this utility model: the inner wall of the polytetrafluoroethylene inner retaining ring is interference-fitted with the outer wall of the lower connector, and the outer wall of the polytetrafluoroethylene outer retaining ring is interference-fitted with the inner wall of the outer jacket.

[0012] Beneficial Effects: The thermal recovery packer of this utility model, due to the use of an outer sleeve consisting of an outer sleeve body and a sealing end at the lower end of the outer sleeve body, with the sealing end threadedly connected to the lower cap, and the inner wall of the sealing end slidingly sealing against the outer wall of the lower connector, forms an annular hydraulic cylinder between the inner wall of the outer sleeve body and the outer wall of the lower connector. An annular setting piston is installed inside the hydraulic cylinder, and the lower end of the locking spring outer sleeve is inserted into the hydraulic cylinder and connected to the setting piston. The hydraulic cylinder between the annular piston and the sealing end is filled with a thermal expansion medium. The packer features a locking spring groove on its outer wall, within which a locking spring is installed. A one-way toothed ring that engages with the locking teeth of the locking spring is located on the inner wall of the locking spring outer sleeve. By filling the hydraulic cylinder with a thermally expanding medium, the packer automatically sets at high temperatures. No special tools or pressure testing from the tubing are required during the setting process. Furthermore, the packer automatically adjusts the setting pressure under high-temperature conditions, ensuring stable sealing performance. The engagement of the locking spring and its outer sleeve prevents reverse movement of the locking spring outer sleeve during downhole temperature fluctuations, which could lead to setting failure. The use of composite sealing ring grooves on both the inner and outer walls of the annular piston, with O-rings and PTFE retaining rings embedded within these grooves, prevents slow leakage of the thermally expanding medium in the hydraulic cylinder after setting under high temperature and pressure, thus enhancing the sealing effect. Because of the design of the locking spring, which is a C-shaped open elastic metal locking spring and a one-way toothed ring, the C-shaped open elastic metal locking spring is retracted within the locking spring insert groove during assembly. Under its own elastic force, it continuously generates radial expansion force, ensuring that the locking teeth of the locking spring can quickly insert into the one-way toothed ring when passing through the locking spring outer sleeve. This achieves timely locking and prevents the locking spring outer sleeve from moving in the opposite direction, which would cause the compression-type combined rubber sleeve to leak force. This ensures that the packer will not fail due to changes in external pressure after setting. The technical feature of fixing the locking spring outer sleeve with the setting shear pin prevents malfunction of the locking spring outer sleeve, making the thermal recovery packer of this utility model easy to install and use. Due to the use of the interference fit between the inner wall of the PTFE inner retaining ring and the outer wall of the lower connector, and the interference fit between the outer wall of the PTFE outer retaining ring and the inner wall of the outer sleeve, the PTFE inner retaining ring slides and seals with the outer wall of the lower connector, and the PTFE outer retaining ring slides and seals with the inner wall of the outer sleeve. This ensures a good sealing effect while reducing the frictional resistance during the setting process of the annular piston. It also allows for greater setting force to the compression-type combined rubber sleeve using a limited thermal expansion medium, further improving the setting effect. Attached Figure Description

[0013] The thermal recovery packer of this utility model will be further described in detail below with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the axial cross-sectional structure of the thermal recovery packer of this utility model;

[0015] Figure 2 This is a partially enlarged view of the locking spring portion in the thermal recovery packer of this utility model;

[0016] Figure 3 This is a partially enlarged view of the annular piston portion in the thermal recovery packer of this utility model. DETAILED DESCRIPTION

[0017] like Figure 1 As shown, the thermal recovery packer of this utility model includes an upper connector 1 and a lower connector 13 connected together by threads. An adjusting cap 2 is installed on the upper connector and is screwed onto the outer wall of the upper connector by threads. The lower connector is a tubular lower connector with a stepped cylindrical surface. From bottom to top, a lower protective cap 12, an outer sleeve 11, a locking spring outer sleeve 4, and a compression-type combined rubber sleeve 3 are installed on the outer wall of the lower connector. The upper end of the locking spring outer sleeve is fixed to the outer wall of the lower connector by a seated shear pin 5. The outer sleeve is composed of an outer sleeve body 111 and a sealing end 112 at the lower end of the outer sleeve body. The sealing end is threadedly connected to the lower protective cap, and the inner wall of the sealing end slides and seals with the outer wall of the lower connector, thereby forming an annular hydraulic cylinder 9 between the inner wall of the outer sleeve body and the outer wall of the lower connector. An annular seated piston 8 is installed in the hydraulic cylinder. The lower end of the locking spring outer sleeve is inserted into the hydraulic cylinder and connected to the seated piston by threads. The hydraulic cylinder between the annular piston and the sealing end is filled with a thermal expansion medium 10. The thermal expansion medium is kerosene, 98% alcohol, water, or other liquids that expand in volume after preheating.

[0018] like Figure 2 As shown, a locking spring mounting groove 14 is opened on the outer wall of the lower connector, a locking spring 6 is installed in the locking spring mounting groove, and a one-way toothed ring 7 that cooperates with the locking teeth of the locking spring is provided on the inner wall of the locking spring outer sleeve.

[0019] like Figure 3 As shown, the inner wall of the annular piston is provided with an O-ring sealing ring groove 16 and a composite sealing ring groove 15. An O-ring 18 and a polytetrafluoroethylene inner retaining ring 17 are embedded in the composite sealing ring groove.

[0020] The outer wall of the annular piston is provided with an O-ring sealing ring groove and a composite sealing ring groove. An O-ring and a polytetrafluoroethylene outer retaining ring 19 are embedded in the composite sealing ring groove.

[0021] The inner wall of the sealing end has an O-ring sealing ring groove and a composite sealing ring groove. An O-ring and a polytetrafluoroethylene inner retaining ring are embedded in the composite sealing ring groove.

[0022] The inner wall of the PTFE inner retaining ring is interference-fitted with the outer wall of the lower connector, and the outer wall of the PTFE outer retaining ring is interference-fitted with the inner wall of the outer jacket.

[0023] Preferably, two composite sealing ring grooves are provided on both the inner and outer walls of the annular piston.

[0024] Preferably, the locking spring is a C-shaped open elastic metal locking spring, which is made of a hard metal material with a certain elasticity, such as stainless steel or alloy steel.

[0025] The working principle of this thermal recovery packer is as follows: The packer is lowered into the designated position on the casing using an oil pipe. High-temperature steam is injected into the casing through the oil pipe. The thermal expansion medium filling the hydraulic cylinder expands upon heating, pushing the piston and locking spring sleeve towards the compression-type combined rubber cylinder. This breaks the setting shear pin, and the locking spring sleeve applies axial pressure to the compression-type combined rubber cylinder, causing it to expand radially and seal the annular space between the oil pipe and the casing. During the movement of the locking spring sleeve towards the compression-type combined rubber cylinder, the locking teeth of the C-shaped open elastic metal locking spring quickly engage with the one-way toothed ring of the locking spring sleeve, ensuring that the locking spring sleeve can only move unidirectionally towards the compression-type combined rubber cylinder. When the thermal expansion medium expands to its limit, the locking spring... The outer sleeve is locked to ensure that the compression-type combined rubber sleeve will not fail due to leakage when the temperature drops. During the movement of the annular piston driven by the thermal expansion medium, the inner and outer PTFE inner and outer retaining rings of the piston prioritize contact and sealing with the outer wall of the lower connector and the inner wall of the outer sleeve, before the O-ring. This ensures a good seal while reducing the resistance to piston movement. In addition, the combination of PTFE outer and inner retaining rings with O-rings in the composite sealing ring groove further improves the sealing effect and prevents slow leakage of the thermal expansion medium during long-term setting of the thermal recovery packer, ensuring that the thermal recovery packer of this invention remains sealed for a long time without failure. When it is necessary to unseal, stop injecting high-temperature steam into the tubing. After the thermal recovery packer cools down, the compression-type combined rubber sleeve will shrink slightly radially due to thermal expansion and contraction. By lifting the tubing string, the packer can be removed from the casing. The thermal recovery packer of this invention can operate for a long time in a downhole environment of 17 MPa and 360°C.

Claims

1. A thermal recovery packer, comprising an upper connector and a lower connector connected together by threads, wherein an adjusting cap is mounted on the upper connector, and the lower connector is a tubular lower connector with a stepped cylindrical surface, and a lower protective cap, an outer sleeve, a locking spring outer sleeve, and a compression-type combined rubber sleeve are sequentially mounted on the outer wall of the lower connector, characterized in that: The outer sleeve consists of an outer sleeve body and a sealing end at the lower end of the outer sleeve body. The sealing end is threadedly connected to the lower protective cap. The inner wall of the sealing end body slides and seals with the outer wall of the lower connector, thereby forming an annular hydraulic cylinder between the inner wall of the outer sleeve body and the outer wall of the lower connector. An annular setting piston is installed in the hydraulic cylinder. The lower end of the locking spring outer sleeve is inserted into the hydraulic cylinder and connected to the setting piston. The hydraulic cylinder between the annular piston and the sealing end is filled with a thermal expansion medium. A locking spring embedding ring groove is opened on the outer wall of the lower connector. A locking spring is installed in the locking spring embedding ring groove. A one-way toothed ring that engages with the locking teeth of the locking spring is provided on the inner wall of the locking spring outer sleeve.

2. The thermal recovery packer according to claim 1, characterized in that: The inner wall of the annular piston is provided with an O-ring sealing ring groove and a composite sealing ring groove. An O-ring and a polytetrafluoroethylene inner retaining ring are embedded in the composite sealing ring groove.

3. The thermal recovery packer according to claim 2, characterized in that: The outer wall of the annular piston is provided with an O-ring sealing ring groove and a composite sealing ring groove. An O-ring and a polytetrafluoroethylene outer retaining ring are embedded in the composite sealing ring groove.

4. The thermal recovery packer according to claim 3, characterized in that: Two composite sealing ring grooves are provided on both the inner and outer walls of the annular piston.

5. The thermal recovery packer according to any one of claims 1 to 4, characterized in that: The locking spring is a C-shaped open locking spring.

6. The thermal recovery packer according to claim 5, characterized in that: The upper end of the locking spring sleeve is fixed to the outer wall of the lower connector by a seat seal scissor pin.

7. The thermal recovery packer according to claim 1, characterized in that: The inner wall of the sealing end has an O-ring sealing ring groove and a composite sealing ring groove. An O-ring and a polytetrafluoroethylene inner retaining ring are embedded in the composite sealing ring groove.

8. The thermal recovery packer according to any one of claims 2, 3, 4 or 7, characterized in that: The inner wall of the PTFE inner retaining ring is interference-fitted with the outer wall of the lower connector, and the outer wall of the PTFE outer retaining ring is interference-fitted with the inner wall of the outer jacket.

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