Device for disassembling wellhead blind plate screwed plug under pressure in long shut-in well

Abstract

The utility model discloses a device for disassembling a wellhead blind plate screwed plug under pressure during long shut-in of a well, the lower end of the wellhead blind plate screwed plug is screwed at the upper end of an oil-string casing coupling, a sealing sleeve is sleeved on the periphery of the oil-string casing coupling, and the lower end of the sealing sleeve is fixed on the oil-string casing coupling through a plurality of slips. An annular space between the periphery of the upper part of the oil-string casing coupling and the sealing sleeve is filled with a sealing ring; the periphery of the upper end of the wellhead blind plate screwed plug is fixedly sleeved with a grabbing disc, the grabbing disc is located in an inner cavity of the connecting sleeve, a cross-shaped sinking groove is formed in the upper end face of the grabbing disc, and the lower end of the connecting sleeve is connected with the sealing sleeve. A semi-closed blowout preventer is installed at the upper end of the connecting sleeve, a cross-shaped clamping jaw at the lower end of the disassembling wrench is embedded into a cross-shaped sinking groove of the grabbing disc, and the rod portion of the disassembling wrench extends upwards along the axis of the semi-closed blowout preventer. The device can prevent the blind plate screwed plug from flying out to hurt people and prevent crude oil from leaking when the blind plate screwed plug is disassembled, safe operation under pressure in the disassembling process is achieved, and environmental pollution is avoided.

Description

Technical Field

[0001] This utility model relates to a long shut-in well plugging tool, and more particularly to a long shut-in well pressurized wellhead blind plate plugging device, belonging to the technical field of oilfield downhole operation tools. Background Technology

[0002] In the past, some oil wells were temporarily sealed after production ceased due to a lack of exploitable value, typically by installing blind flange plugs at the wellhead. Years later, it may be necessary to re-inspect the production of long-shutdown wells, or to permanently seal them by injecting cement due to safety hazards caused by wellhead leakage. Since most of these wells have been out of production for many years, and some are located in farmland, fishponds, or factories, the pressure inside the wells is often unknown, and there is no pressure relief channel. Therefore, re-inspecting the wells or permanently sealing them requires removing the blind flange plugs.

[0003] The conventional method is to directly unscrew the plug. However, due to the long shutdown time, a certain amount of pressure usually accumulates after the wellbore pressure recovers. Furthermore, as oilfield development progresses and water injection work intensifies, formation pressure may become disordered, or even locally high. When disassembling the wellhead cap of a long-shutdown well, a blowout accident is likely to occur. Moreover, the blind flange may fly out instantly upon direct disassembly, causing injury and crude oil leakage pollution accidents. Some wells are located in farmland, fish ponds, or factories, where blowout prevention and pollution prevention requirements are high.

[0004] Currently, some technicians have researched and applied simple drainage tubes or similar simple blowout preventers, and installed simple drainage and sealing materials such as ordinary rubber, cotton yarn, and hemp rope. However, these tools do not have an effective sealing mechanism and cannot withstand high pressure. The problems of blowout prevention and pollution prevention have not been completely solved, and there are significant safety hazards. Utility Model Content

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0006] The purpose of this invention is to solve the problem of blowout prevention when dismantling a wellhead under pressure during a long-term shutdown well. It provides a device for dismantling a blind plate plug under pressure during a long-term shutdown well, which avoids the blind plate plug flying out and causing injury or crude oil leakage accidents at the moment of dismantling. It achieves safe operation under pressure during the dismantling process and avoids environmental pollution.

[0007] To solve the above technical problems, this utility model provides a device for removing a blind flange plug under pressure in a long-closed well. The lower end of the blind flange plug is screwed to the upper end of the oil layer casing coupling. A sealing sleeve is fitted around the outer periphery of the oil layer casing coupling. The lower end of the sealing sleeve is fixed to the oil layer casing coupling by multiple slips. A sealing ring is filled in the annular space between the upper outer periphery of the oil layer casing coupling and the sealing sleeve. A gripping disc is fitted and fixed around the upper outer periphery of the blind flange plug. The gripping disc is located in the inner cavity of the connecting sleeve, and a cross groove is provided on the upper end face of the gripping disc. The lower end of the connecting sleeve is connected to the sealing sleeve. A semi-sealed blowout preventer is installed at the upper end of the connecting sleeve. The cross claw of the lower end of the removal wrench is embedded in the cross groove of the gripping disc, and the rod of the removal wrench extends upward along the axis of the semi-sealed blowout preventer.

[0008] Furthermore, the lower end of the oil layer casing coupling is supported on an annular steel plate, and the annular steel plate is fixed in the upper port of the surface casing coupling.

[0009] Furthermore, each of the aforementioned slips is located in the annular space between the lower port of the sealing sleeve and the outer periphery of the oil layer casing coupling, and is symmetrically located on the outer periphery of the oil layer casing coupling; each slip fixing bolt is screwed into the screw hole on the lower circumference of the sealing sleeve and its inner end abuts against the outer wall of the slip.

[0010] Furthermore, the inner wall of the sealing sleeve is provided with an annular inner convex ring, and the inner circumferential wall of the annular inner convex ring is clearance-fitted with the outer wall of the oil layer sleeve coupling; the sealing ring is a V-shaped rubber core, and a rubber core pressure ring is pressed on the top of the V-shaped rubber core, and the outer circumference of the rubber core pressure ring is screwed into the upper screw hole of the sealing sleeve.

[0011] Furthermore, the lower flange of the connecting sleeve is mated with the upper flange of the sealing sleeve and fixed by bolts, and a metal sealing ring is embedded between the sealing surfaces of the lower flange of the connecting sleeve and the upper flange of the sealing sleeve.

[0012] Furthermore, the side wall of the connecting sleeve is provided with a pressure relief outlet, and the pressure relief outlet is connected to a pressure relief valve and a pressure relief pipe.

[0013] Furthermore, the sidewall of the gripping disc is fixed to the upper outer periphery of the wellhead blind flange plug by multiple hexagonal screws.

[0014] Furthermore, the upper end of the disassembly wrench is provided with a hexagonal head or a square tenon.

[0015] Furthermore, the upper end of the disassembly wrench is provided with a radial through hole, and a force-applying rod is inserted into the radial through hole.

[0016] Furthermore, the lower female thread of the semi-sealed blowout preventer is screwed to the upper male thread of the connecting sleeve, and the through diameter of the semi-sealed gate in the semi-sealed blowout preventer matches the outer diameter of the handle of the disassembly wrench.

[0017] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. It adopts a clamp connection mechanism, which is reliable and has a split installation, making it convenient to relocate and install. It can meet the needs of long-term well opening and re-inspection operations in farmland, fish ponds or factories.

[0018] 2. An external sealing mechanism is designed on the outer wall of the casing, which has the characteristics of well pressure-assisted sealing and solves the problem of sealing the outer wall of the casing;

[0019] 3. A professional blowout preventer is used during the disassembly of the rotary seal, which is easy to operate and provides safe and reliable protection against blowouts and contamination;

[0020] 4. The device has a connecting flange at the upper end and sits directly on the annular steel plate of the surface casing coupling at the lower end, which ensures reliable load-bearing capacity. The device also has a large internal diameter, which provides the conditions for the installation of the live well equipment if the pressure release time is long and subsequent well workover is required. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein:

[0022] Figure 1 This is a schematic diagram of the structure of the device for removing blind flange plugs at the wellhead under pressure during long-term well closure according to this utility model;

[0023] Figure 2 This is a schematic diagram of the wellhead structure for long-term shut-in wells according to this utility model;

[0024] Figure 3 A diagram showing the state of the wellhead after the slip sealing mechanism has been installed.

[0025] Figure 4 A diagram showing the state after the grabbing disc is installed on the upper end of the blind flange plug at the wellhead;

[0026] Figure 5 This is a diagram showing the condition of the wellhead after the blowout preventer and pollution control mechanism have been installed.

[0027] Reference numerals: 1. Surface casing coupling; 2. Annular steel plate; 3. Oil layer casing; 4. Oil layer casing coupling; 5. Wellhead blind flange plug; 6. Slip; 6a. Slip fixing bolt; 7. Sealing sleeve; 8. V-shaped rubber core; 9. Rubber core pressure ring; 10. Gripping disc; 10a. Socket head cap screw; 11. Connecting sleeve; 11a. Metal sealing ring; 12. Blowout valve; 13. Blowout pipe; 14. Semi-sealed blowout preventer; 15. Removal wrench; 16. Adding rod. Detailed Implementation

[0028] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0029] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] like Figure 1 As shown, the long-closed well pressure-operated blind flange plugging device of this utility model includes three main parts: a slip fixing and sealing mechanism, a blowout and pollution prevention mechanism, and a claw unhooking mechanism. The slip fixing and sealing mechanism includes a sealing sleeve 7, four slips 6, slip fixing bolts 6a, a V-shaped rubber core 8, and a rubber core pressure ring 9. The four slips 6 are located above the annular steel plate 2 at the upper end of the surface casing coupling 1, in the annular space between the lower end of the sealing sleeve 7 and the outer periphery of the oil layer casing coupling 4, and are symmetrically located on the outer periphery of the oil layer casing coupling 4. The lower circumference of the sealing sleeve 7 has four sets of slip screw holes, two at the top and two at the bottom, corresponding to the two countersunk holes on the outer wall of the slip 6; the four sets of eight slip fixing bolts 6a are screwed into the slip screw holes of the sealing sleeve 7, and the inner end of the slip fixing bolt 6a is embedded in the countersunk hole on the outer wall of the slip 6, thus fastening the four slips 6 to the lower outer wall of the oil layer casing coupling 4.

[0032] The inner wall of the sealing sleeve 7 is provided with an annular inner convex ring, and the inner circumferential wall of the annular inner convex ring is clearance-fitted with the outer wall of the oil layer casing coupling 4. A V-shaped rubber core 8 is placed in the annular space above the annular inner convex ring, and a rubber core pressure ring 9 is pressed above the V-shaped rubber core 8. The outer circumference of the rubber core pressure ring 9 is provided with external threads, which are screwed into the upper threaded hole of the sealing sleeve 7.

[0033] The blowout preventer and contamination prevention mechanism includes a semi-sealed blowout preventer 14 and a connecting sleeve 11. The lower flange of the connecting sleeve 11 is mated with the upper flange of the sealing sleeve 7 and fixed by a large bolt. A metal sealing ring 11a is embedded between the sealing surfaces of the lower flange of the connecting sleeve 11 and the upper flange of the sealing sleeve 7 to improve sealing performance. The upper outer periphery of the connecting sleeve 11 is provided with a male thread that connects to the female thread at the lower port of the semi-sealed blowout preventer 14.

[0034] The side wall of the connecting sleeve 11 is provided with a blowout relief outlet, which can be located on the 50mm thick flange side wall. The inner port of the blowout relief outlet communicates with the inner cavity of the connecting sleeve 11 through a radial through hole. The blowout relief outlet is connected to a blowout valve 12 and a blowout pipe 13. When the blind flange plug 5 is removed from the wellhead and overflow occurs at the wellhead, the semi-sealed blowout preventer 14 is closed, the blowout valve 12 is opened, and the overflow is discharged into a collection tank or other safe container through the blowout pipe 13.

[0035] The gripper release mechanism includes a gripping disc 10, eight hexagon socket screws 10a, and a release wrench 15. The lower end of the gripping disc 10 is fitted onto the upper outer circumference of the wellhead blind flange plug 5 with clearance. Two rows of screw holes are provided on the circumference of the gripping disc 10, and each screw hole is screwed with a hexagon socket screw 10a. The inner ends of the four hexagon socket screws 10a in the lower circumference abut against the upper circumferential wall of the wellhead blind flange plug 5, and the inner ends of the four hexagon socket screws 10a in the middle circumference abut against the upper outer circumference of the wellhead blind flange plug 5. In this way, the gripping disc 10 is fixed to the upper end of the wellhead blind flange plug 5.

[0036] The upper end of the gripping disc 10 is closed, and the upper end face is provided with a cross groove. The lower end of the disassembly wrench 15 is provided with a cross claw that matches the cross groove. After the cross claw of the disassembly wrench 15 is inserted into the cross groove of the gripping disc 10, the gripping disc 10 can be rotated by the disassembly wrench 15, thereby uncoupling the wellhead blind plug 5.

[0037] The disassembly wrench 15 can be rotated using a pipe wrench, or a hexagonal head or square tenon can be provided at the upper end of the disassembly wrench 15 to facilitate rotation of the disassembly wrench 15; or a radial through hole can be provided at the upper end of the disassembly wrench 15, and the force-adding rod 16 can be inserted into the radial through hole to easily rotate the disassembly wrench 15.

[0038] The working principle and complete operation process of this utility model are as follows:

[0039] S1. First, clean the outer surface of the oil layer sleeve coupling 4, remove burrs and rust, and apply lubricating sealant. Figure 2The diagram shows the wellhead structure of a long shut-in well. An annular steel plate 2 is screwed into the female thread of the upper port of the surface casing coupling 1. The lower end of the oil layer casing coupling 4 is suspended on the annular steel plate 2. The upper end of the oil layer casing 3 passes through the central hole of the annular steel plate 2 and connects to the lower port of the oil layer casing coupling 4. A wellhead blind flange plug 5 is connected to the upper port of the oil layer casing coupling 4. The upper port of the wellhead blind flange plug 5 is a blind flange, and the male thread on the lower outer periphery of the plug is screwed into the female thread of the upper port of the oil layer casing coupling 4.

[0040] S2, Install the 6-piece clamp: (e.g.) Figure 3 As shown, first place four slips 6 on the annular steel plate 2 at the upper end of the surface casing coupling 1, evenly distributed along the outer circumference of the oil layer casing coupling 4. Insert the sealing sleeve 7 from the upper end of the oil layer casing coupling 4. Align the slip screw hole on the lower circumference of the sealing sleeve 7 with the countersunk hole on the outer wall of the slip 6. Screw the slip fixing bolt 6a into the slip screw hole of the sealing sleeve 7 and insert the inner end of the slip fixing bolt 6a into the countersunk hole on the outer wall of the slip 6. After tightening the four slip fixing bolts 6a, press the slip 6 against the surface, so that the slip 6 tightly bites the outer wall of the oil layer casing coupling 4.

[0041] S3. Install V-shaped adhesive core 8: as follows Figure 3 As shown, a V-shaped rubber core 8 is placed in the annular space between the upper port of the sealing sleeve 7 and the outer wall of the oil layer casing coupling 4. Then, a rubber core pressure ring 9 is installed above the V-shaped rubber core 8. The external thread of the rubber core pressure ring 9 is screwed into the female thread at the upper port of the sealing sleeve 7 and tightened with a special pressure ring wrench. The V-shaped rubber core 8 is pressed, and a seal is achieved between the oil layer casing coupling 4 and the sealing sleeve 7.

[0042] S4. Install capture disk 10: (e.g.) Figure 4 As shown, the gripping disc 10 in the gripper uncoupling mechanism is placed on the upper outer periphery of the wellhead blind plate plug 5, and eight internal hexagon screws 10a are tightened. The inner end of each internal hexagon screw 10a firmly presses against the outer wall of the wellhead blind plate plug 5, and the torque is transmitted under the action of friction.

[0043] S5, Install connecting sleeve 11: as follows Figure 5 As shown, the lower flange of the connecting sleeve 11 is fixedly connected to the upper flange of the sealing sleeve 7 with large bolts, and the metal sealing ring 11a between the two flanges is pressed tightly; the vent pipe 13 and the vent valve 12 are connected at the vent and pressure relief outlet on the side wall of the connecting sleeve 11.

[0044] S6. Install the semi-sealed blowout preventer 14: Screw the lower female thread of the semi-sealed blowout preventer 14 onto the upper male thread of the connecting sleeve 11.

[0045] S7. Disassembly Operation:

[0046] S7.1, such as Figure 1 As shown, the cross claw at the lower end of the disassembly wrench 15 is inserted into the cross groove at the upper end of the gripping disc 10.

[0047] S7.2. Close the semi-sealing gate of the semi-sealed blowout preventer 14 appropriately, straighten the disassembly wrench 15, and leave a slight gap to reduce the rotation resistance of the shackle.

[0048] S7.3. Manually use a wrench or pipe wrench to drive the disassembly wrench 15 to rotate, loosening the male thread at the lower end of the wellhead blind flange plug 5 until it is completely disengaged;

[0049] S7.4 When oil and gas flow is detected at the wellhead, immediately close the semi-sealing gate of the semi-sealed blowout preventer 14 so that it is tightly held around the outer periphery of the disassembly wrench 15.

[0050] S8. Release: Open the release valve 12 to release pressure through the release pipe 13, and control the release through the release valve 12.

[0051] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements may also be made to the present utility model. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A device for removing a blind flange plug during pressurized well shut-in, wherein the lower end of the blind flange plug (5) is screwed to the upper end of the casing coupling (4) in the oil layer, characterized in that... A sealing sleeve (7) is fitted around the outer periphery of the oil layer casing coupling (4). The lower end of the sealing sleeve (7) is fixed to the oil layer casing coupling (4) by multiple slips (6). A sealing ring is filled in the annular space between the upper outer periphery of the oil layer casing coupling (4) and the sealing sleeve (7). The upper outer periphery of the wellhead blind plug (5) is fitted with a gripping disc (10). The gripping disc (10) is located in the inner cavity of the connecting sleeve (11) and the upper end face of the gripping disc (10) is provided with a cross groove. The lower end of the connecting sleeve (11) is connected to the sealing sleeve (7). A semi-sealed blowout preventer (14) is installed at the upper end of the connecting sleeve (11). The cross claw at the lower end of the disassembly wrench (15) is embedded in the cross groove of the gripping disc (10). The rod of the disassembly wrench (15) extends upward along the axis of the semi-sealed blowout preventer (14).

2. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The lower end of the oil layer casing coupling (4) is supported on the annular steel plate (2), which is fixed in the upper port of the surface casing coupling (1).

3. The device for removing blind flange plugs from wellheads under pressure as described in claim 2, characterized in that, Each of the slips (6) is located in the annular space between the lower port of the sealing sleeve (7) and the outer periphery of the oil layer casing coupling (4), and is symmetrically located on the outer periphery of the oil layer casing coupling (4); each slip fixing bolt (6a) is screwed into the screw hole on the lower circumference of the sealing sleeve (7) and the inner end abuts against the outer wall of the slip (6).

4. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The sealing sleeve (7) has an annular inner convex ring on its inner wall. The inner circumferential wall of the annular inner convex ring is in clearance fit with the outer wall of the oil layer casing coupling (4). The sealing ring is a V-shaped rubber core (8). A rubber core pressure ring (9) is pressed on the top of the V-shaped rubber core (8). The outer circumference of the rubber core pressure ring (9) is screwed into the upper screw hole of the sealing sleeve (7).

5. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The lower flange of the connecting sleeve (11) is mated with the upper flange of the sealing sleeve (7) and fixed by bolts. A metal sealing ring (11a) is embedded between the sealing surfaces of the lower flange of the connecting sleeve (11) and the upper flange of the sealing sleeve (7).

6. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The side wall of the connecting sleeve (11) is provided with a pressure relief outlet, and the pressure relief outlet is connected to a pressure relief valve (12) and a pressure relief pipe (13).

7. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The sidewall of the gripping disc (10) is fixed to the upper outer periphery of the wellhead blind plug (5) by a plurality of internal hexagonal screws (10a).

8. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The upper end of the disassembly wrench (15) is provided with a hexagonal head or a square tenon.

9. The device for removing blind flange plugs from wellheads under pressure as described in claim 1, characterized in that, The upper end of the disassembly wrench (15) is provided with a radial through hole, and a force-adding rod (16) is inserted into the radial through hole.

10. The device for removing blind flange plugs from a wellhead under pressure according to any one of claims 1 to 9, characterized in that, The lower female thread of the semi-sealed blowout preventer (14) is screwed to the upper male thread of the connecting sleeve (11), and the diameter of the semi-sealed gate in the semi-sealed blowout preventer (14) matches the outer diameter of the rod of the disassembly wrench (15).

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