Hydraulic locking device for oil gas wellhead

Abstract

The hydraulic locking device for the oil and gas wellhead comprises a pipe head four-way joint, a hanger assembly is arranged in the pipe head four-way joint in a sleeved mode, a step face is arranged on the inner wall of the pipe head four-way joint, a flange matched with the step face is arranged on the outer wall of the hanger assembly, the lower end face of the flange is set on the step face, and a mounting hole is formed in the pipe head four-way joint in the radial direction. The installation holes correspond to the upper end faces of the flanges in position, and hydraulic locking mechanisms are arranged in the installation holes and can stretch into the pipe head four-way joint to be clamped and locked with the upper end faces of the flanges. Locking and unlocking of the oil and casing pipe hanger assembly are achieved in a hydraulic locking mode, oil and casing pipe columns are prevented from being ejected out when the pressure in a well is too high, operation is easy, convenient, safe and reliable, the labor intensity of workers is relieved, the working efficiency is improved, the problem that locking components are embroidered due to seepage is solved, and the service life of the device is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas drilling and production equipment technology, and specifically relates to a hydraulic locking device for oil and gas wellheads. Background Technology

[0002] Wellhead equipment is the main equipment at the top of an oil and gas well for controlling and regulating oil and gas production. It consists of three main parts: the casing head, the tubing head, and the production (gas) tree. It is a key piece of equipment for suspending the downhole tubing string and casing string, sealing the annular space between the tubing and casing, and controlling oil and gas well production. During operation, a locking device is needed to hold the tubing and casing string in place to prevent them from being pushed out when the well pressure is too high. Currently, most wellhead equipment for tubing and casing heads both domestically and internationally uses a set screw locking method, tightening or loosening the screw through the threaded joint. This method is inconvenient and inefficient. Furthermore, during drilling and tubing / casing tripping operations, mud and drilling fluid can easily seep into the threaded gaps between the set screw and the tubing / casing head, preventing the set screw from being tightened or loosened properly. When the sealing component is damaged and needs replacement, the set screw must be removed to replace the sealing component, which is cumbersome and inconvenient, and may damage the threads of the set screw. Therefore, it is urgent to improve the locking method of the existing wellhead equipment in order to facilitate the locking / unlocking function of the tubing string and casing string in a convenient, quick and stable manner. Summary of the Invention

[0003] The purpose of this invention is to provide a solution to the problems in the prior art, such as cumbersome operation and low work efficiency when locking the set screw, and component rusting or deformation damage caused by leakage.

[0004] The technical solution adopted in this invention is a hydraulic locking device for oil and gas wellheads, including a pipe head four-way connector, a hanger assembly sleeved in the pipe head four-way connector, a stepped surface on the inner wall of the pipe head four-way connector, a flange that mates with the stepped surface on the outer wall of the hanger assembly, the lower end face of the flange being seated on the stepped surface, a mounting hole radially opened in the pipe head four-way connector, the mounting hole being positioned corresponding to the upper end face of the flange, a hydraulic locking mechanism being installed in the mounting hole, the hydraulic locking mechanism being able to extend into the inside of the pipe head four-way connector and engage and lock with the upper end face of the flange.

[0005] The invention is further characterized by:

[0006] The hydraulic locking mechanism includes a locking rod. One end of the locking rod extends into the inside of the pipe head four-way through the mounting hole, and the other end is fitted with a sealing component, a pressure cap, and a hydraulic cylinder from the inside to the outside. The locking rod can be driven by the hydraulic cylinder to extend out from the end face of the hydraulic cylinder. A backstop block is movably connected to the end face of the hydraulic cylinder. The hydraulic cylinder and the pressure cap are connected and fixed in the groove on the outer surface of the pipe head four-way by bolts.

[0007] One end of the locking rod extending into the four-way connector is conical, fitting with the upper end face of the flange. The other end is a three-stage stepped shaft structure with different outer diameters, decreasing sequentially from the inside to the outside. The inner surface shape of the hydraulic cylinder matches the stepped shaft, forming a locking drive oil chamber and an unlocking drive oil chamber between the locking rod, the gland, and the hydraulic cylinder. The outer wall of the hydraulic cylinder is equipped with a locking hydraulic interface and an unlocking hydraulic interface. Two hydraulic flow channels are provided inside the cylinder wall. The locking hydraulic interface is connected to the locking drive oil chamber through the hydraulic flow channels, and the unlocking hydraulic interface is connected to the unlocking drive oil chamber through the hydraulic flow channels.

[0008] A compression spring is fitted on the outermost stepped shaft of the locking rod, with both ends of the compression spring abutting against the inner side of the hydraulic cylinder end face and the adjacent stepped shaft end face, respectively.

[0009] A sealing ring a is installed on the contact surface between the gland and the locking rod, a sealing ring b is installed on the contact surface between the gland and the hydraulic cylinder, and sealing rings c and d are respectively installed on the contact surface between the hydraulic cylinder and the stepped shaft part of the locking rod.

[0010] A retaining block is movably connected to the end face of the hydraulic cylinder. Specifically, threaded holes are provided on the upper part of the end face of the hydraulic cylinder and at the edge of the retaining block. The retaining block is hinged to the hydraulic cylinder by bolts, and a handle is provided on the other side of the retaining block opposite to the threaded hole.

[0011] The sealing assembly is a combination structure of multiple sealing layers. The sealing layer has a V-shaped cross section and includes a metal sealing layer and a rubber sealing layer. The V-shaped openings of the metal sealing layer and the rubber sealing layer face the inside of the pipe head four-way and are stacked alternately.

[0012] An annular seal assembly is fitted onto the flange on the outer wall of the suspension assembly.

[0013] The beneficial effects of this invention are as follows: The hydraulic locking device for oil and gas wellheads provided by this invention involves installing a hanger assembly within a four-way connector. The inner wall of the four-way connector has a stepped surface, and the outer wall of the hanger assembly has a flange that mates with the stepped surface. The lower end face of the flange is seated on the stepped surface. The four-way connector has radially opened mounting holes, the positions of which correspond to the upper end face of the flange. A hydraulic locking mechanism is installed within the mounting holes. By injecting hydraulic oil into the hydraulic locking mechanism, the hanger assembly can be locked or unlocked. This replaces the existing method of using set screws for locking, making operation simple, convenient, safe, and reliable. It reduces the labor intensity of personnel and improves work efficiency. Furthermore, the hydraulic locking method improves the problem of the original threaded set screws seizing due to leakage, making it more stable when the sealing components need to be replaced, preventing damage to internal connecting components, and extending the service life of the device. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the hydraulic locking device for oil and gas wellheads according to the present invention;

[0015] Figure 2 This is a partially enlarged view of the hydraulic locking mechanism in the device of the present invention;

[0016] Figure 3 This is an end view of the hydraulic locking mechanism in the device of the present invention.

[0017] In the diagram, 1. Suspension assembly, 2. Annular seal assembly, 3. Pipe head four-way, 4. Locking rod, 5. Sealing assembly, 6. Gland, 7. Hydraulic cylinder, 8. Compression spring, 9. Anti-reverse block, 10. Locking drive oil chamber, 11. Unlocking drive oil chamber, 12. Unlocking hydraulic interface, 13. Locking hydraulic interface. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] The present invention provides a hydraulic locking device for oil and gas wellheads, such as... Figure 1 As shown, the assembly includes a pipe head four-way 3, within which a hanger assembly 1 is fitted. The lower end of the hanger assembly 1 is generally connected to the oil and casing, while the upper end is connected to other oil production equipment. The inner wall of the pipe head four-way 3 has a stepped surface, which can be an inner conical surface protruding inward around the inner circumference of the inner wall. The outer wall of the hanger assembly 1 has a flange that mates with the stepped surface. The lower end face of the flange is an outer conical surface that mates with the stepped surface. The lower end face of the flange is seated on the stepped surface. An annular sealing assembly 2 is fitted onto the flange on the outer wall of the hanger assembly 1, which can seal the annular space inside the casing to prevent leakage. The pipe head four-way 3 has a radially opened mounting hole, the position of which corresponds to the upper end face of the flange. A hydraulic locking mechanism is installed in the mounting hole. Driven by externally input hydraulic pressure, the hydraulic locking mechanism can extend into the inside of the pipe head four-way 3 and engage with the upper end face of the flange on the outer wall of the hanger assembly 1 to lock it in place, thereby limiting and fixing the hanger assembly 1.

[0020] like Figure 2As shown, the specific structure of the hydraulic locking mechanism includes a locking rod 4. After passing through the mounting hole, one end of the locking rod 4 extends into the inside of the pipe head four-way 3. The end of the locking rod 4 extending into the pipe head four-way 3 is conical, and the curvature of its conical surface matches the curvature of the upper end face of the flange on the outer wall of the suspension assembly 1. The other end is a three-stage stepped shaft structure with different outer diameters, divided into three stages from the inside to the outside, with the outer diameter of each stage decreasing sequentially. On the locking rod 4, from the inside of the pipe head four-way 3 to its outside direction, a sealing assembly 5, a pressure cap 6, and a hydraulic cylinder 7 are sequentially fitted. The sealing assembly 5 and the pressure cap 6 are fitted onto the locking rod 4. On the inner side of the largest outer diameter first-stage stepped shaft, sealing component 5 is used to seal the mounting hole of the locking device to prevent mud, drilling fluid, etc. from leaking out through the mounting hole. The gland 6 abuts against the inner end of the largest outer diameter first-stage stepped shaft and seals it on the outer surface of the pipe head four-way 3. The hydraulic cylinder 7 is fitted tightly against the gland 6 and sleeved on the outside of the third-stage stepped shaft of the locking rod 4. The outer surface of the pipe head four-way 3 has a groove matching the shape of the gland 6. The hydraulic cylinder 7 and the gland 6 are radially connected and fixed in the groove on the outer surface of the pipe head four-way 3 by bolts. The inner surface shape of the hydraulic cylinder 7 matches the stepped shaft, ensuring proper locking. A locking drive oil chamber 10 and an unlocking drive oil chamber 11 are formed between the rod 4, the pressure cap 6, and the hydraulic cylinder 7, separated by a stepped shaft with the largest outer diameter. The locking drive oil chamber 10 is located in the outer space, and the unlocking drive oil chamber 11 is located in the inner space. A through hole matching the diameter of the outermost stepped shaft is opened on the cross-section of the hydraulic cylinder 7. The outermost stepped shaft of the locking rod 4 can extend from the end face of the hydraulic cylinder 7, that is, the locking rod 4 can slide radially inside the hydraulic cylinder 7. A locking hydraulic interface 13 and an unlocking hydraulic interface 12 are provided on the outer wall of the hydraulic cylinder 7, and two hydraulic flow channels are provided inside the cylinder wall. The locking hydraulic interface 13 is connected to the locking drive oil chamber 10 through a hydraulic flow channel, and the unlocking hydraulic interface 12 is connected to the unlocking drive oil chamber 11 through a hydraulic flow channel. It can be understood that by connecting the locking hydraulic interface 13 or the unlocking hydraulic interface 12, liquid flow can be injected from the outside into the locking drive oil chamber 10 or the unlocking drive oil chamber 11 to push the locking rod 4 to slide back and forth. A stop block 9 is movably connected at the position where the locking rod 4 extends on the end face of the hydraulic cylinder 7. The stop block 9 can block and limit the locking rod 4 to ensure that the position of the locking rod 4 is fixed when it is closed.

[0021] Based on the above structure, a compression spring 8 is sleeved on the outermost stepped shaft of the locking rod 4. The two ends of the compression spring 8 abut against the inner side of the end face of the hydraulic cylinder 7 and the adjacent end face of the stepped shaft, respectively. The thrust of the compression spring 8 allows the locking rod 4 to remain locked even in the depressurization state, ensuring stability when switching between pressurization and depressurization operations.

[0022] In addition, a sealing ring a is installed on the contact surface between the pressure cap 6 and the locking rod 4, a sealing ring b is installed on the contact surface between the pressure cap 6 and the hydraulic cylinder 7, and sealing rings c and d are respectively provided on the contact surface between the hydraulic cylinder 7 and the stepped shaft part of the locking rod 4. The above-mentioned sealing rings reinforce and seal the various joint parts of the locking drive oil chamber 10 and the unlocking drive oil chamber 11 to ensure the sealing effect of the two drive oil chambers and prevent leakage under high pressure.

[0023] Additionally, a structure is provided herein in which the end face of the hydraulic cylinder 7 is movably connected to the anti-reverse block 9, such as... Figure 3 As shown, its specific structure is as follows: threaded holes are provided on the upper part of the end face of the hydraulic cylinder 7 and at the edge of the anti-locking block 9. The anti-locking block 9 is hinged to the hydraulic cylinder 7 by bolts. A handle is provided on the other side of the anti-locking block 9 opposite to the threaded hole. When the anti-locking block 9 is in use, it automatically blocks the hydraulic cylinder hole under its own weight, limiting the locking rod 4 and keeping the locking rod 4 in a locked state. When it is necessary to unlock, the anti-locking block 9 is rotated 180°, and the locking rod 4 can be released through the center hole of the hydraulic cylinder 7 to achieve unlocking.

[0024] To achieve a better sealing effect, the sealing assembly 5 can be configured as a combination structure of multiple sealing layers. Each sealing layer has a V-shaped cross section. The material of the sealing layer can be a metal sealing layer or a rubber sealing layer. When setting it up, the V-shaped openings of the metal sealing layer and the rubber sealing layer are facing the inside of the pipe head four-way 3 and are stacked alternately. This arrangement makes the V-shaped openings face the internal pressure direction, thereby achieving the pressure-assisted sealing function.

[0025] The working principle of this invention is as follows: When it is necessary to lock the locking device to the oil and sleeve hanger assembly 1, hydraulic oil is injected through the locking hydraulic interface 13, driving the locking rod 4 to move towards the axis of the hanger assembly 1. The tapered surface at the end of the locking rod 4 engages with the upper end face of the flange on the outer wall of the hanger assembly 1, thereby achieving a limiting lock on the hanger assembly 1. At the same time, a stop block 9 is provided to prevent the locking rod 4 from retracting, ensuring locking safety. When it is necessary to unlock the locking device from the hanger assembly 1 or replace the sealing component 5, the stop block 9 is rotated 180° to completely unobstruct the cylinder bore. At this time, although the pressure is released, the locking rod 4 remains locked under the thrust of the compression spring 8, preventing it from falling off directly after pressure release and causing a safety accident. Then, hydraulic oil is injected through the unlocking hydraulic interface 12, driving the locking rod 4 to move away from the axis of the hanger assembly 1, thereby unlocking.

[0026] Through the above-described method, the device provided by this invention can lock and unlock the oil and casing hanger assembly, locking the oil and casing string during operation to prevent them from being pushed out when the well pressure is too high. Hydraulic control of locking / unlocking reduces labor intensity, improves operational safety and reliability, increases work efficiency, and extends service life.

[0027] Example 1

[0028] The hydraulic locking device for oil and gas wellheads provided in this embodiment 1 includes a pipe head four-way 3, a hanger assembly 1 sleeved in the pipe head four-way 3, a stepped surface on the inner wall of the pipe head four-way 3, a flange on the outer wall of the hanger assembly 1 that mates with the stepped surface, the lower end face of the flange being seated on the stepped surface, an annular sealing assembly 2 being sleeved on the flange on the outer wall of the hanger assembly 1, a mounting hole radially opened in the pipe head four-way 3, the mounting hole being positioned corresponding to the upper end face of the flange, a hydraulic locking mechanism being installed in the mounting hole, the hydraulic locking mechanism being able to extend into the inside of the pipe head four-way 3 and engage and lock with the upper end face of the flange.

[0029] Example 2

[0030] The hydraulic locking device for oil and gas wellheads provided in Embodiment 2 includes a pipe head four-way 3, a hanger assembly 1 fitted inside the pipe head four-way 3, a stepped surface on the inner wall of the pipe head four-way 3, and a flange on the outer wall of the hanger assembly 1 that mates with the stepped surface. The lower end face of the flange is seated on the stepped surface. An annular sealing assembly 2 is fitted on the flange on the outer wall of the hanger assembly 1. The pipe head four-way 3 has a radially opened mounting hole, the position of which corresponds to the upper end face of the flange. A hydraulic locking mechanism is installed in the mounting hole. The hydraulic locking mechanism includes a locking rod 4. One end of the locking rod 4 extends into the pipe head four-way 3 through the mounting hole. The end of the locking rod 4 extending into the pipe head four-way 3 is conical and mates with the upper end face of the flange. The other end is a three-stage stepped shaft structure with different outer diameters, from the inside out. The diameter decreases sequentially. A sealing assembly 5, a pressure cap 6, and a hydraulic cylinder 7 are sequentially fitted onto the locking rod 4 from the inside out. The inner surface shape of the hydraulic cylinder 7 matches the stepped shaft. A locking drive oil chamber 10 and an unlocking drive oil chamber 11 are formed between the locking rod 4, the pressure cap 6, and the hydraulic cylinder 7. A locking hydraulic interface 13 and an unlocking hydraulic interface 12 are provided on the outer wall of the hydraulic cylinder 7. Two hydraulic flow channels are provided inside the cylinder wall. The locking hydraulic interface 13 is connected to the locking drive oil chamber 10 through the hydraulic flow channel, and the unlocking hydraulic interface 12 is connected to the unlocking drive oil chamber 11 through the hydraulic flow channel. The locking rod 4 can be driven by the hydraulic cylinder 7 to extend from the end face of the hydraulic cylinder 7. A stop block 9 is movably connected to the end face of the hydraulic cylinder 7. The hydraulic cylinder 7 and the pressure cap 6 are connected and fixed in the groove on the outer surface of the pipe head four-way 3 by bolts.

[0031] Example 3

[0032] The hydraulic locking device for oil and gas wellheads provided in Embodiment 3, based on Embodiment 2, has a compression spring 8 sleeved on the outermost stepped shaft of the locking rod 4. The two ends of the compression spring 8 abut against the inner side of the end face of the hydraulic cylinder 7 and the adjacent end face of the stepped shaft, respectively. A sealing ring a is installed on the contact surface between the pressure cap 6 and the locking rod 4, a sealing ring b is installed on the contact surface between the pressure cap 6 and the hydraulic cylinder 7, and sealing rings c and d are respectively provided on the contact surface between the hydraulic cylinder 7 and the stepped shaft part of the locking rod 4.

[0033] The specific structure of the anti-reverse block 9 movably connected to the end face of the hydraulic cylinder 7 is as follows: threaded holes are opened at the upper part of the end face of the hydraulic cylinder 7 and at the edge of the anti-reverse block 9; the anti-reverse block 9 is hinged to the hydraulic cylinder 7 by bolts; and a handle is provided on the other side of the anti-reverse block 9 opposite to the threaded hole.

[0034] Among them, the sealing component 5 is a combination structure of multiple sealing layers. The sealing layer has a V-shaped cross section and includes a metal sealing layer and a rubber sealing layer. The V-shaped openings of the metal sealing layer and the rubber sealing layer face the inside of the pipe head four-way 3 and are stacked alternately.

Claims

1. Hydraulic locking device for oil and gas wellheads, characterized in that, The application relates to a hydraulic locking mechanism for a pipe head four-way joint, which comprises a pipe head four-way joint (3) in which a hanger assembly (1) is sleeved, the inner wall of the pipe head four-way joint (3) is provided with a stepped surface, the outer wall of the hanger assembly (1) is provided with a flange matched with the stepped surface, the lower end surface of the flange is sealed on the stepped surface, a mounting hole is formed in the pipe head four-way joint (3) in the radial direction, the mounting hole is arranged at a position corresponding to the upper end surface of the flange, and a hydraulic locking mechanism is arranged in the mounting hole and can be inserted into the pipe head four-way joint (3) to be clamped and locked with the upper end surface of the flange.

2. Hydraulic locking device for oil and gas wellheads according to claim 1, characterized in that, The hydraulic locking mechanism comprises a locking rod (4), one end of the locking rod (4) is inserted into the pipe head four-way joint (3) through the mounting hole, the other end of the locking rod (4) is sequentially sleeved with a sealing assembly (5), a gland (6) and a hydraulic cylinder (7) from inside to outside, the locking rod (4) can be driven by the hydraulic cylinder (7) to be extended from the end surface of the hydraulic cylinder (7), the end surface of the hydraulic cylinder (7) is movably connected with a retreat-stop block (9), and the hydraulic cylinder (7) and the gland (6) are connected and fixed on the outer surface groove of the pipe head four-way joint (3) through bolts.

3. Hydraulic locking device for oil and gas wellheads according to claim 2, characterized in that, The end of the locking rod (4) inserted into the pipe head four-way joint (3) is conical and matched with the upper end surface of the flange, and the other end is a three-stage stepped shaft structure with different outer diameters, the outer diameters of the three-stage stepped shaft structure are sequentially reduced from inside to outside, the inner surface shape of the hydraulic cylinder (7) is matched with the stepped shaft, locking drive oil cavities (10) and unlocking drive oil cavities (11) are formed between the locking rod (4), the gland (6) and the hydraulic cylinder (7), the outer wall of the hydraulic cylinder (7) is provided with a locking hydraulic interface (13) and an unlocking hydraulic interface (12), two hydraulic flow channels are arranged in the cylinder wall, the locking hydraulic interface (13) is connected with the locking drive oil cavities (10) through the hydraulic flow channels, and the unlocking hydraulic interface (12) is connected with the unlocking drive oil cavities (11) through the hydraulic flow channels.

4. Hydraulic locking device for oil and gas wellheads according to claim 3, characterized in that, A compression spring (8) is sleeved on the outermost stepped shaft of the locking rod (4), and the two ends of the compression spring (8) are respectively abutted against the inner side of the end surface of the hydraulic cylinder (7) and the end surface of the adjacent stepped shaft.

5. Hydraulic locking device for oil and gas wellheads according to claim 4, characterized in that, A sealing ring a is arranged on the contact surface between the gland (6) and the locking rod (4), a sealing ring b is arranged on the contact surface between the gland (6) and the hydraulic cylinder (7), and a sealing ring c and a sealing ring d are respectively arranged on the contact surfaces between the hydraulic cylinder (7) and the stepped shaft part of the locking rod (4).

6. The hydraulic locking device for oil and gas wellheads according to claim 2, characterized in that, The end surface of the hydraulic cylinder (7) is movably connected with the retreat-stop block (9), and the specific structure is that a threaded hole is formed on the upper part of the end surface of the hydraulic cylinder (7) and the edge position of the retreat-stop block (9), the retreat-stop block (9) is hinged with the hydraulic cylinder (7) through bolts, and the other side of the retreat-stop block (9) opposite to the threaded hole is provided with a handle.

7. The hydraulic locking device for oil and gas wellheads according to claim 2, characterized in that, The sealing assembly (5) is a combined structure of multiple sealing layers, the cross section of the sealing layer is V-shaped, the sealing layer comprises a metal sealing layer and a rubber sealing layer, and the V-shaped openings of the metal sealing layer and the rubber sealing layer face the inside of the pipe head four-way joint (3) and are alternately stacked.

8. Hydraulic locking device for oil and gas wellheads according to any of claims 1-7, characterized in that, The annular sealing assembly (2) is sleeved on the flange of the outer wall of the hanger assembly (1).

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