Sealing device for annular space of oil well casing

Abstract

The utility model relates to the technical field of well repair, in particular to an oil well casing annular space sealing device. Comprising a cylindrical main body, an annular groove is formed in the outer edge of the main body, the outer side of the main body is sleeved with an elastic rubber sleeve, the upper end and the lower end of the elastic rubber sleeve are fixedly connected with the outer edge of the main body, an air pipe is fixed to the upper end of the main body and communicates with the annular groove, grooves are formed in the upper end and the lower end of the main body, and limiting assemblies are arranged in the grooves; limiting units are arranged at the upper end and the lower end of the main body, and each limiting unit comprises a plurality of limiting pieces. The rotating rod is driven to the horizontal position through the up-down limiting assembly, rigid limitation on axial expansion of the elastic rubber sleeve is formed, and the rubber sleeve is forced to mainly expand in the radial direction. The design obviously increases the contact pressure between the rubber sleeve and the inner wall of the intermediate casing, overcomes the problem of insufficient sealing pressure in the traditional scheme, and effectively prevents liquid leakage during water injection.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of well repair technology field, specifically to a kind of oil well casing annular space sealing device. BACKGROUND

[0002] Oil well casing is divided into surface casing, technical casing and oil layer casing from outside to inside, annular steel plate is welded between the upper portion of surface casing and technical casing to block the annular space between surface casing and technical casing, annular steel plate is welded between the upper portion of technical casing and oil layer casing to block the annular space between technical casing and oil layer casing, and wellhead device is installed on the upper portion of oil layer casing. Due to corrosion and other reasons, oil layer casing is damaged, well repair operation is needed, part of oil layer casing is taken out from well bottom, and new oil layer casing is replaced. Since oil layer casing and technical casing are fixed by annular steel plate welding, annular steel plate on the upper portion of technical casing needs to be cut off by oxyacetylene flame, so that oil layer casing and technical casing are separated. However, the damage of oil layer casing causes the existence of combustible gas in the annular space between oil layer casing and technical casing, and flame cutting exists the risk of wellhead fire and explosion. The existing technical measures are: drilling hole on technical casing, injecting water into technical casing, replacing combustible gas in technical casing by water filling measure, when water level reaches the drilling position, it is considered that combustible gas in technical casing has been exhausted, at this time, oxyacetylene cutting can be used to avoid fire and explosion caused by flame cutting. But due to the damage of oil layer casing, oil layer casing and technical casing are connected, water injected into technical casing flows into formation, water level in technical casing cannot be maintained, and internal combustible gas cannot be completely exhausted, so that annular steel plate on the upper portion of technical casing cannot be cut safely.

[0003] In order to solve the above technical problems, the patent file with publication number CN219101296U discloses an oil well casing annular space sealing device, which comprises a plugging rod, a flexible sealing structure is installed at the lower end of the plugging rod, the flexible sealing structure can be radially retracted and unfolded, and when retracted, it can be lowered into the oil layer casing, and when lowered to the oil layer casing fracture, it can be unfolded to seal with the inner wall of the technical casing. In use, the oil layer casing is cut off at a certain distance from the lower part by using a casing cutter special for well repair, the lower oil layer casing sinks due to gravity, and a certain gap is formed at the cut seam; then the pressure-bearing rod and the elastic rubber pad are retracted upward, and are inserted from the upper port of the oil layer casing, when reaching the oil layer casing fracture position, the oil layer casing loses the restraining effect on the elastic rubber pad and the pressure-bearing rod, the elastic rubber pad automatically unfolds, the edge part of the elastic rubber pad is lapped on the inner wall of the technical casing to form a bowl shape, and at the same time, the pressure-bearing rod automatically swings and opens downward under the action of its own gravity to support below the elastic rubber pad; at this time, a proper amount of fine soil and clean water are added into the oil layer casing from the upper port of the oil layer casing, because the elastic rubber pad is sealed with the inner wall of the technical casing, the fine soil and water will gather above the elastic rubber pad to form a fine soil sediment layer and a liquid surface, when the liquid surface reaches the drilling position at the upper part of the technical casing, it can be considered that the combustible gas in the technical casing has been discharged, even if there is a small amount of residual combustible gas, it will not cause safety hazards, at this time, the annular steel plate between the technical casing and the oil layer casing can be cut off by using flame cutting technology, the oil layer casing and the technical casing are separated, and the well repair condition is reached. However, the elastic rubber pad of the technical solution has small extrusion force on the inner wall of the technical casing, so the sealing pressure is small, and the water injected into the oil pipe and the technical casing is easy to leak during the water injection and gas discharge process. SUMMARY

[0004] The main purpose of the utility model is to provide an oil well casing annular space sealing device with good sealing performance.

[0005] In order to achieve the above purpose, the technical scheme provided by the utility model is:

[0006] An oil well casing annular space sealing device, which comprises a cylindrical main body, an annular groove is formed on the outer edge of the main body, an elastic rubber sleeve is sleeved on the outer side of the main body, the upper and lower ends of the elastic rubber sleeve are fixedly connected with the outer edge of the main body, an air pipe is fixedly arranged on the upper end of the main body, the air pipe is communicated with the annular groove, recesses are formed on the upper and lower ends of the main body, limiting assemblies are arranged in the recesses, a driving unit is arranged in the main body, the driving unit can drive the two limiting assemblies to move in the axial direction of the main body, and the moving directions of the two limiting assemblies are opposite, limiting units are arranged on the upper and lower ends of the main body, the limiting unit comprises a plurality of limiting pieces, and the plurality of limiting pieces are arranged in the circumferential direction of the shaft of the main body; the limiting piece comprises an ear plate fixed on the main body, a rotating rod is rotatably connected to the ear plate through a rotating shaft, the rotating rod is connected with the ear plate through a torsional spring, when the two limiting assemblies are away from each other, the rotating rod rotates and tends to be parallel to the horizontal plane, after the rotating rod is in contact with the main body, the limiting assembly can stop the rotation of the rotating rod; after the rotating rods on the upper and lower sides are horizontal, the rotating rods on the upper and lower sides can limit the expansion amount of the elastic rubber sleeve in the axial direction during the expansion of the elastic rubber sleeve, and a fixed pipe is fixedly arranged on the limiting assembly on the upper side.

[0007] Specifically, the limiting assembly comprises a baffle and a limiting ring which are concentric with the main body, the baffle is close to the center of the main body, the baffle and the limiting ring are fixedly connected through a connecting rod, after the limiting ring and the baffle are arranged in the recess, the limiting ring is in contact with the rotating rod part on the inner side of the rotating shaft along the outer edge and makes the rotating rod keep an inclined state, and the torsional spring is energized, when the two limiting assemblies are away from each other, the rotating rod rotates, and when the rotating rod is in contact with the main body, the baffle is in contact with the rotating rod part on the inner side of the rotating shaft and stops the rotation of the rotating rod.

[0008] Specifically, the driving unit comprises a double-shaft motor fixed in the main body, the double-shaft motor is concentric with the main body, a lead screw is fixedly arranged on the output shaft of the double-shaft motor, the lead screw is rotatably and sealingly connected with the main body, the screw directions of the two lead screws are opposite, the lead screw penetrates the baffle and the limiting ring on one side of the lead screw, and the lead screw is threadedly connected with the baffle.

[0009] Specifically, a plurality of insertion rods are fixedly arranged on the baffle, the axial direction of the insertion rod is parallel to the axial direction of the main body, and the insertion rod is slidingly inserted into the insertion hole of the main body.

[0010] Specifically, the torsional spring is sleeved on the rotating shaft, one end of the torsional spring is fixedly connected with the ear plate, and the other end of the torsional spring is fixedly connected with the rotating rod.

[0011] Specifically, the double-shaft motor is a low-speed brake motor.

[0012] Specifically, the lower end of the fixed pipe is fixedly arranged on the limiting ring on the upper side, and the fixed pipe is concentric with the main body.

[0013] Compared with the prior art, the oil well casing annular space sealing device has the following beneficial effects:

[0014] 1. The upper and lower limit components stop the rotating rod from rotating when it reaches the horizontal position, forming a rigid limit for the axial expansion of the elastic rubber sleeve, forcing the rubber sleeve to expand mainly in the radial direction. This design significantly increases the contact pressure between the elastic rubber sleeve and the inner wall of the technical casing, overcoming the problem of insufficient sealing pressure in traditional solutions, effectively preventing liquid leakage during water injection.

[0015] 2. When the rotating rod contacts the main body horizontally, the baffle contacts the rotating rod to form a physical stop, preventing the rotating rod from rotating when the elastic rubber sleeve expands, ensuring that the rotating rod effectively limits the axial expansion of the elastic rubber sleeve.

[0016] 3. The expansion of the elastic rubber sleeve is protected by the rigid limit, preventing damage from excessive stretching and extending the service life. The reset device can be quickly recovered after the limit component, suitable for multiple workover operations, reducing the cost of single use.

[0017] 4. High sealing pressure ensures that the technical casing and the tubing annular space are completely isolated, and the liquid level rises quickly during water injection to replace combustible gas, eliminating the risk of flame cutting explosion. Compared with traditional water injection solutions, this device achieves stable liquid level through pneumatic sealing, improving operation safety.

[0018] 5. Fast sealing and stable water injection shorten the exhaust time, avoiding delays caused by repeated adjustment of the sealing device. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the device below the oil pipe.

[0020] Figure 2 is a schematic diagram of the device.

[0021] Figure 3 is a top view of the device.

[0022] Figure 4 is a schematic diagram of the elastic rubber sleeve after expansion and sealing contact with the inner wall of the technical casing.

[0023] Figure 5 is a schematic diagram of the elastic rubber sleeve of the device after expansion.

[0024] The component names in the drawings are: 1, surface casing, 2, technical casing, 3, oil pipe, 4, ring plate, 5, main body, 6, ring groove, 7, elastic rubber sleeve, 8, air pipe, 9, groove, 10, double-shaft motor, 11, lead screw, 12, limit ring, 13, baffle, 14, connecting rod, 15, insertion rod, 16, ear plate, 17, rotating rod, 18, fixed pipe. DETAILED DESCRIPTION

[0025] Clearly, the described embodiments are merely part of the embodiments of the present utility model, rather than all the embodiments.

[0026] The oil well casing is composed of an outer surface casing 1, a technical casing 2 and a pipe 3 from outside to inside, and a ring plate 4 is welded between the upper part of the outer surface casing 1 and the technical casing 2 to seal the annular space between the outer surface casing 1 and the technical casing 2.

[0027] Embodiment one: refer to Figures 1-5 As shown in the figure, an oil well casing annular space sealing device comprises a cylindrical main body 5, a ring groove 6 is formed in the outer edge of the main body 5, an elastic rubber sleeve 7 is sleeved on the outer side of the main body 5, the upper and lower ends of the elastic rubber sleeve 7 are fixedly connected with the outer edge of the main body 5, and an air pipe 8 is fixedly connected to the upper end of the main body 5 and communicates with the ring groove 6.

[0028] The lower part of the pipe 3 is cut off at a certain distance by using a casing cutter for well repair, the part of the pipe 3 below the cutting seam sinks due to gravity, and a certain spacing is formed at the cutting seam. The air pipe 8 communicates with the air pump. Then the main body 5 is lowered to the position of the pipe 3 break, the ring groove 6 is inflated by the air pump, and the elastic rubber sleeve 7 expands to form a sealing contact with the inner wall of the technical casing 2. Then water is injected into the part of the pipe 3 above the cutting seam, and when the annular space of the technical casing 2 and the pipe 3 is filled with water, the ring plate 4 connecting the technical casing 2 and the pipe 3 can be cut.

[0029] After the cutting of the ring plate 4 connecting the casing 2 and the pipe 3 is completed, the part of the pipe 3 above the cutting seam is taken out, then the compressed air in the ring groove 6 is released, and the elastic rubber sleeve 7 is restored to take out the device from the technical casing 2.

[0030] In this embodiment, the expansion amount of the elastic rubber sleeve 7 in the axial direction cannot be limited when it needs to have sufficient sealing pressure with the inner wall of the technical casing 2, and the air injection amount needs to be increased in the ring groove 6, so the sealing efficiency is low. After increasing the air injection amount, the elastic rubber sleeve 7 is easy to be damaged.

[0031] Embodiment two: based on embodiment one, refer to Figures 1-5 As shown in the figure, recesses 9 are formed in the upper and lower ends of the main body 5, and limiting assemblies are arranged in the recesses 9.

[0032] A driving unit is arranged in the main body 5, the driving unit can drive the two limiting assemblies to move in the axial direction of the main body 5, and the moving directions of the two limiting assemblies are opposite.

[0033] The limiting assembly comprises a baffle plate 13 concentric with the main body 5 and a limiting ring 12, the baffle plate 13 is close to the center of the main body 5, and the baffle plate 13 and the limiting ring 12 are fixedly connected through a connecting rod 14. A plurality of insertion rods 15 are fixed on the baffle plate 13, the axial direction of the insertion rod 15 is parallel to the axial direction of the main body 5, and the insertion rod 15 is slidingly inserted into the insertion hole of the main body 5.

[0034] A fixed tube 18 is fixed on the upper limiting assembly. Specifically, the lower end of the fixed tube 18 is fixed on the upper limiting ring 12, and the fixed tube 18 is concentric with the main body 5. By arranging the fixed tube 18, the device is conveniently lowered to the oil pipe 3 fracture position.

[0035] After the limiting ring 12 and the baffle plate 13 are located in the groove 9, the outer edge of the limiting ring 12 is in contact with part of the rotating rod 17 on the inner side of the rotating shaft and makes the rotating rod 17 keep an inclined state, and the torsional spring is stored.

[0036] When the two limiting assemblies are away from each other, the rotating rod 17 rotates, and when the rotating rod 17 contacts the main body 5, the baffle plate 13 contacts part of the rotating rod 17 on the inner side of the rotating shaft and stops the rotating rod 17.

[0037] The driving unit comprises a double-shaft motor 10 fixed in the main body 5, and the double-shaft motor 10 is a low-speed power-off brake motor. The double-shaft motor 10 is concentric with the main body 5, and a lead screw 11 is fixed concentrically on the output shaft of the double-shaft motor 10, the lead screw 11 is in rotational sealing connection with the main body 5, and the screw directions of the upper and lower lead screws 11 are opposite. The lead screw 11 penetrates the baffle plate 13 and the limiting ring 12 on one side of the lead screw 11, and the lead screw 11 is in threaded connection with the baffle plate 13.

[0038] The upper end and the lower end of the main body 5 are provided with limiting units, and the limiting unit comprises a plurality of limiting pieces which are uniformly arranged according to the axial circle of the main body 5.

[0039] The limiting piece comprises an ear plate 16 fixed on the main body 5, a rotating rod 17 rotatably connected to the ear plate 16 through a rotating shaft, the rotating rod 17 is connected to the ear plate 16 through a torsional spring, the torsional spring is sleeved on the rotating shaft, one end of the torsional spring is fixedly connected to the ear plate 16, and the other end of the torsional spring is fixedly connected to the rotating rod 17.

[0040] When the two limiting assemblies are away from each other, the rotating rod 17 rotates and tends to be parallel to the horizontal plane, and after the rotating rod 17 contacts the main body 5, the limiting assembly can stop the rotating rod 17. After the upper and lower rotating rods 17 are horizontal, the upper and lower rotating rods 17 can limit the expansion amount of the elastic rubber sleeve 7 in the axial direction during the expansion of the elastic rubber sleeve 7.

[0041] When the device is lowered to the oil pipe 3 fracture position, the double shaft motor 10 is started, the lead screws 11 on the upper and lower sides rotate and make the limiting assemblies on the upper and lower sides away from each other. In the process of the limiting assemblies on the upper and lower sides away from each other, under the elastic force of the torsion spring, the rotating rod 17 rotates and tends to be parallel to the horizontal plane. When the rotating rod 17 is parallel to the horizontal plane, the rotating rod 17 contacts the main body 5. With the limiting assemblies on the upper and lower sides continue to move away from each other, when the baffle 13 contacts the rotating rod 17 on the inner side of the rotating shaft, under the blocking effect of the baffle 13 and the blocking effect of the main body 5, the rotating rod 17 is locked.

[0042] Then the annular groove 6 is inflated, and after the elastic rubber sleeve 7 expands, the upper rotating rod 17 and the lower rotating rod 17 can limit the expansion amount of the elastic rubber sleeve 7 in the axial direction, thereby ensuring that the expanded elastic rubber sleeve 7 is in rapid sealing contact with the inner wall of the technical sleeve 2. The sealing pressure of the expanded elastic rubber sleeve 7 and the inner wall of the technical sleeve 2 can be improved to prevent leakage when water is injected.

[0043] Then the part of the oil pipe 3 above the slotted is injected with water, and when the water fills the annular space of the technical sleeve 2 and the oil pipe 3, the annular plate 4 connecting the technical sleeve 2 and the oil pipe 3 can be cut.

[0044] After the annular plate 4 is cut, the double shaft motor 10 is started to make the limiting assemblies on the upper and lower sides close to each other, and when the limiting assemblies are restored, the rotating rod 17 is restored and is in an inclined state to prevent the device from being pulled out of the technical sleeve 2. Then the compressed air in the annular groove 6 is released, and after the elastic rubber sleeve 7 is restored, the device can be taken out of the technical sleeve 2.

[0045] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An oil well casing annulus sealing device comprising a cylindrical body (5), characterised in that, The outer edge of the main body (5) is provided with a ring groove (6), and the outer side of the main body (5) is provided with an elastic rubber sleeve (7). The upper and lower ends of the elastic rubber sleeve (7) are fixedly connected with the outer edge of the main body (5). The upper end of the main body (5) is fixedly provided with an air pipe (8). The air pipe (8) is communicated with the ring groove (6). The upper and lower ends of the main body (5) are both provided with a recess (9). The recess (9) is provided with a limiting assembly. The main body (5) is provided with a driving unit. The driving unit can drive the two limiting assemblies to move in the axial direction of the main body (5). The movement directions of the two limiting assemblies are opposite. The upper end and the lower end of the main body (5) are both provided with a limiting unit. The limiting unit comprises a plurality of limiting pieces. The plurality of limiting pieces are evenly arranged according to the axial circle of the main body (5). The limiting piece comprises an ear plate (16) fixed on the main body (5). The ear plate (16) is rotatably connected with a rotating rod (17) through a rotating shaft. The rotating rod (17) is connected with the ear plate (16) through a torsional spring. When the two limiting assemblies are away from each other, the rotating rod (17) rotates and tends to be parallel to the horizontal plane. After the rotating rod (17) contacts with the main body (5), the limiting assembly can stop the rotation of the rotating rod (17). After the rotating rods (17) at the upper and lower positions are horizontal, the upper and lower rotating rods (17) can limit the expansion amount of the elastic rubber sleeve (7) in the axial direction during the expansion process of the elastic rubber sleeve (7). The limiting assembly at the upper position is fixedly provided with a fixed pipe (18).

2. An oil well casing annulus sealing device according to claim 1, characterised in that, The limiting assembly comprises a baffle (13) and a limiting ring (12) which are concentric with the main body (5). The baffle (13) is close to the center of the main body (5). The baffle (13) and the limiting ring (12) are fixedly connected through a connecting rod (14). After the limiting ring (12) and the baffle (13) are located in the recess (9), the outer edge of the limiting ring (12) is in contact with part of the rotating rod (17) inside the rotating shaft and makes the rotating rod (17) keep an inclined state. The torsional spring is energized. When the two limiting assemblies are away from each other, the rotating rod (17) rotates. When the rotating rod (17) contacts with the main body (5), the baffle (13) is in contact with part of the rotating rod (17) inside the rotating shaft and stops the rotation of the rotating rod (17).

3. An oil well casing annulus sealing device according to claim 2, characterised in that, The driving unit comprises a double-shaft motor (10) fixed in the main body (5). The double-shaft motor (10) is concentric with the main body (5). The output shaft of the double-shaft motor (10) is fixedly provided with a lead screw (11) which is concentric. The lead screw (11) is rotatably and sealingly connected with the main body (5). The screw directions of the upper and lower lead screws (11) are opposite. The lead screw (11) penetrates the baffle (13) and the limiting ring (12) on one side thereof. The lead screw (11) is threadedly connected with the baffle (13).

4. An oil well casing annulus sealing device according to claim 2, wherein, A plurality of plug rods (15) are fixedly arranged on the baffle (13). The axial direction of the plug rod (15) is parallel to the axial direction of the main body (5). The plug rod (15) is slidingly inserted into the plug hole of the main body (5).

5. An oil well casing annulus sealing device according to claim 1 wherein, The torsional spring is sleeved on the rotating shaft. One end of the torsional spring is fixedly connected with the ear plate (16). The other end of the torsional spring is fixedly connected with the rotating rod (17).

6. An oil well casing annulus sealing device according to claim 3, wherein, The double-shaft motor (10) is a low-speed power-off brake motor.

7. An oil well casing annulus sealing device according to claim 1 wherein, The lower end of the fixed pipe (18) is fixedly arranged on the limiting ring (12) at the upper position. The fixed pipe (18) is concentric with the main body (5).

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