Wellhead sealing device and sealing method for gas recovery well

Abstract

The well mouth sealing device comprises an oil pressure conversion connector, a first channel and a second channel which are parallel to the axis are formed in the oil pressure conversion connector, a steel wire rope penetrates through the first channel, and connectors corresponding to the first channel and the second channel are fixedly connected with a first outer cylinder and a second outer cylinder respectively; a first sealing assembly is arranged between the inner wall of the second outer cylinder and the steel wire rope, a second sealing assembly is arranged at the joint of the oil pressure conversion connector and the second outer cylinder, a hydraulic opening is fixedly connected to the side wall of the second channel, an adjusting assembly is arranged at the other end of the second outer cylinder, and a connecting assembly is arranged at the other end of the first outer cylinder. The steel wire rope penetrates through the first sealing assembly and the second sealing assembly along the axis. Meanwhile, the invention further discloses a wellhead sealing method using the device. Sealing is conducted through the two-stage hydraulic sealing structure, the pressing force is adjustable, the sealing strength can be flexibly adjusted according to the actual pressure condition of a wellhead, the sealing effect is effectively guaranteed, and the gas and liquid leakage risk is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and relates to an automatic wellhead sealing device and a gas production wellhead sealing method using the device. Background Art

[0002] During the natural gas production process, since the natural gas in the gas well is under high pressure, the wellhead needs to be sealed to prevent natural gas leakage and fire, explosion and other safety accidents. At the same time, the pressure in the gas well needs to be maintained to ensure that the natural gas can flow smoothly from the bottom of the well to the wellhead, thus ensuring the continuity and stability of the production process.

[0003] Traditional wellhead sealing devices use fixed elastic materials as sealing packing, which relies on the elasticity of the packing itself to achieve sealing. They have high requirements on the surface finish and centering of the sucker rod and cannot automatically adjust the sealing pressure according to the working conditions, and cannot adapt to different production conditions. At the same time, traditional wellhead sealing devices also have problems such as difficult to ensure sealing effect, short service life of packing, lack of waste liquid collection and monitoring functions, which seriously restrict the efficient, safe and environmentally friendly development of oil and gas production operations. Summary of the invention

[0004] The purpose of the present invention is to provide a gas wellhead sealing device, which solves the problem in the prior art that the sealing effect cannot be adjusted according to working conditions.

[0005] The technical solution adopted by the present invention is to include an oil pressure conversion joint, in which a first channel and a second channel parallel to the axis are opened, a steel wire rope runs through the first channel, joints corresponding to the first channel and the second channel are respectively fixedly connected to a first outer cylinder and a second outer cylinder, a first sealing assembly is arranged between the inner wall of the second outer cylinder and the steel wire rope, a second sealing assembly is arranged at the connection between the oil pressure conversion joint and the second outer cylinder, a hydraulic port is fixedly connected to the side wall of the second channel, an adjustment assembly is arranged at the other end of the second outer cylinder, a connecting assembly is arranged at the other end of the first outer cylinder, and the steel wire rope passes through the first sealing assembly and the second sealing assembly along the axis.

[0006] The present invention is also characterized in that: A groove is provided at the connection between the oil pressure conversion joint and the second outer cylinder, and the steel wire rope passes through the groove, and the second sealing component is installed in the groove.

[0007] The first sealing assembly includes a first packing sleeved on the outside of the wire rope, and the first packing is tightly attached to the inner wall of the first outer tube. A first piston is provided on the side of the first packing close to the oil pressure conversion joint, and the side of the first piston away from the first packing extends into the first channel, and the first piston is dynamically sealed to the inner wall of the first channel.

[0008] The second sealing assembly includes a second packing arranged in the groove, and the second packing is close to the inner wall of the groove, a second piston is abutted on a side of the second packing close to the second outer tube, an end of the second piston away from the second packing is fixedly connected to a piston rod and extends into the second outer tube, a section of the inner wall of the second outer tube close to the oil pressure conversion joint is dynamically sealed with the piston rod, and a cavity is left between the rest of the inner wall of the second outer tube and the piston rod, and a plurality of overflow holes are provided on the portion of the outer wall of the piston rod corresponding to the cavity of the second outer tube.

[0009] The side wall of the first channel is fixedly connected with a first overflow port, and the first overflow port is a three-way joint. The cavity section of the second outer cylinder is correspondingly connected with a second overflow port, and a straight pipe is fixedly connected between the second overflow port and the first overflow port.

[0010] The connecting assembly includes a connecting head fixedly connected to the other end of the first outer tube, and the connecting head abuts against the first sealing assembly. A connecting groove is provided on the side of the connecting head away from the first outer tube, a choke tube is fixedly connected in the connecting groove, a pressing cap is fixedly connected to the outer side of the connecting head, and a steel wire rope passes through the axis of the choke tube and the connecting groove along the axis.

[0011] The adjustment component includes an upper cover fixedly connected to the other end of the second outer cylinder. An adjustment groove is provided on the surface of the upper cover away from the second outer cylinder. A pressure cap is threadedly connected to the adjusting groove, and a cavity is reserved between the pressure cap and the adjusting groove. The cavity formed by the pressure cap and the adjusting groove is filled with filler, and a steel wire rope passes through the upper cover and the pressure cap along the axis.

[0012] Another technical solution adopted by the present invention is a gas wellhead sealing method, which is specifically implemented according to the following steps: Step 1: Connect the relevant tool string to the wire rope at one end of the connection assembly, connect the electric pump to the hydraulic port, connect the first overflow port to the recovery tank, and install a flow meter at the connection between the two; Step 2: Place the tool string into the gas well and then connect it to the wellhead of the gas well through the connecting assembly; Step 3: Start the electric pump to inject pressure and seal the wellhead of the gas well; Step 4: Observe the flow meter reading in real time during the sealing process. When the flow meter reading is too large, increase the electric pump injection pressure. When the flow meter reading is too small, reduce the electric pump injection pressure.

[0013] Beneficial effects: 1. The present invention uses a two-stage hydraulic sealing structure for sealing, and the clamping force is adjustable. The sealing force can be flexibly adjusted according to the actual pressure of the wellhead, effectively ensuring the sealing effect and reducing the risk of gas and liquid leakage. At the same time, the adjustable clamping force can avoid excessive wear of the packing. Compared with traditional sealing devices, the service life of the packing is greatly extended, the equipment maintenance cost and replacement frequency are reduced, and the operation interruption time is reduced.

[0014] 2. The present invention realizes waste liquid collection by setting an overflow port, reduces the pollution of waste liquid to the environment, and meets environmental protection requirements. At the same time, by monitoring the overflow volume, abnormal sealing conditions can be discovered in time, making it easy to take corresponding measures to maintain the best sealing effect of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the connection structure of various components of the wellhead sealing device of a gas production well according to the present invention; Figure 2 It is a schematic diagram of the connection structure of various parts of the wellhead sealing device of a gas production well of the present invention.

[0016] In the figure: 1, hydraulic conversion joint; 2, first channel; 3, second channel; 4, wire rope; 5, first outer tube; 6, second outer tube; 7, first sealing assembly; 8, second sealing assembly; 9, hydraulic port; 10, adjustment assembly; 11, connecting assembly; 12, first packing; 13, first piston; 14, second packing; 15, second piston; 16, piston rod; 17, overflow hole; 18, first overflow port; 19, second overflow port; 20, straight pipe; 21, connector; 22, connecting groove; 23, choke tube; 24, lower pressure cap; 25, upper cover; 26, adjustment groove; 27, pressure cover; 28, packing. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Embodiment 1: like Figure 1 As shown, it includes an oil pressure conversion joint 1, in which a first channel 2 and a second channel 3 parallel to the axis are opened, a steel wire rope 4 runs through the first channel 2, joints corresponding to the first channel 2 and the second channel 3 are fixedly connected with a first outer cylinder 5 and a second outer cylinder 6 respectively, a first sealing component 7 is arranged between the inner wall of the second outer cylinder 6 and the steel wire rope 4, a second sealing component 8 is arranged at the connection between the oil pressure conversion joint 1 and the second outer cylinder 6, a hydraulic port 9 is fixedly connected to the side wall of the second channel 3, an adjusting component 10 is arranged at the other end of the second outer cylinder 6, a connecting component 11 is arranged at the other end of the first outer cylinder 5, and the steel wire rope 4 passes through the first sealing component 7 and the second sealing component 8 along the axis.

[0019] A groove is provided at the connection between the oil pressure conversion joint 1 and the second outer tube 6, and the steel wire rope 4 passes through the groove, and the second sealing assembly 8 is installed in the groove.

[0020] The device is provided with a first channel 2 and a second channel 3, wherein the first channel 2 is used to accommodate a steel wire rope 4 and the second channel 3 is used to inject high-pressure liquid or gas. The sealing effect is improved by squeezing the first sealing component 7 and sealing the second sealing component 8. The two channels are independent of each other and do not interfere with each other. While providing a stable sealing effect, the gas in the wellhead of the gas well can be prevented from mixing with the pressurized material, thereby affecting the subsequent treatment of the overflow gas.

[0021] Embodiment 2: Based on Example 1: like Figure 1 and Figure 2 As shown, the first sealing assembly 7 includes a first packing 12 sleeved on the outside of the wire rope 4, and the first packing 12 is close to the inner wall of the first outer tube 5, and a first piston 13 is provided on the side of the first packing 12 close to the oil pressure conversion joint 1, and the side of the first piston 13 away from the first packing 12 extends into the first channel 2, and the first piston 13 is dynamically sealed with the inner wall of the first channel 2.

[0022] The injection pressure through the second channel 3 can make the first piston 13 squeeze the first packing 12, so that the first packing 12 is deformed and closely attached to the inner wall of the wire rope 4, thereby achieving sealing and preventing the gas in the wellhead of the gas production well from passing through the first sealing component 7. At the same time, by changing the pressure of the hydraulic substance, the pressure of the first piston 13 on the first packing 12 can be adjusted, thereby adjusting the deformation degree of the first packing 12 and achieving the adjustment of the sealing effect.

[0023] Embodiment three: Based on the second embodiment: like Figure 1 and Figure 2 As shown, the second sealing assembly 8 includes a second packing 14 arranged in the groove, and the second packing 14 is close to the inner wall of the groove, and the second piston 15 is abutted on the side of the second packing 14 close to the second outer tube 6, and the end of the second piston 15 away from the second packing 14 is fixedly connected to the piston rod 16 and extends into the second outer tube 6. A section of the inner wall of the second outer tube 6 close to the oil pressure conversion joint 1 is dynamically sealed with the piston rod 16, and a cavity is left between the rest of the inner wall of the second outer tube 6 and the piston rod 16, and a plurality of overflow holes 17 are provided on the outer wall of the piston rod 16 corresponding to the cavity of the second outer tube 6.

[0024] By adjusting the pressure of the second channel 3, the pressure of the second piston 15 on the second packing 14 can be changed to adjust the sealing effect. At the same time, the overflow hole 17 on the surface of the piston rod 16 can send a small amount of gas passing through the second sealing component 8 into the cavity of the second outer tube 6, thereby reducing the gas pressure by expanding the volume, preventing further leakage of the gas, and facilitating centralized treatment of the leaked gas.

[0025] Embodiment 4: Based on Example 3: like Figure 1 and Figure 2 As shown, the side wall of the first channel 2 is fixedly connected with a first overflow port 18, and the first overflow port 18 is a three-way joint. The cavity section of the second outer tube 6 is correspondingly connected with a second overflow port 19, and a straight pipe 20 is fixedly connected between the second overflow port 19 and the first overflow port 18.

[0026] The two interfaces of the first overflow port 18 are connected to the first channel 2 and the straight pipe 20 respectively, and part of the gas leaked from the oil pressure conversion joint 1 and the piston rod 16 is collected for subsequent processing. At the same time, the sealing effect of the two sealing components can be judged according to the size of the leaked gas flow in the first overflow port 18. When the leaked gas flow is large, the sealing effect of the two sealing components is poor, and when the leaked gas flow is small, the sealing effect of the two components is good. After knowing the sealing effect of the sealing component, it can be flexibly adjusted according to actual needs to meet the different needs of the production site.

[0027] Embodiment five: like Figure 1 and Figure 2 As shown, it includes an oil pressure conversion joint 1, in which a first channel 2 and a second channel 3 parallel to the axis are opened, a steel wire rope 4 runs through the first channel 2, joints corresponding to the first channel 2 and the second channel 3 are fixedly connected with a first outer cylinder 5 and a second outer cylinder 6 respectively, a first sealing component 7 is arranged between the inner wall of the second outer cylinder 6 and the steel wire rope 4, a second sealing component 8 is arranged at the connection between the oil pressure conversion joint 1 and the second outer cylinder 6, a hydraulic port 9 is fixedly connected to the side wall of the second channel 3, an adjusting component 10 is arranged at the other end of the second outer cylinder 6, a connecting component 11 is arranged at the other end of the first outer cylinder 5, and the steel wire rope 4 passes through the first sealing component 7 and the second sealing component 8 along the axis.

[0028] A groove is provided at the connection between the oil pressure conversion joint 1 and the second outer tube 6, and the steel wire rope 4 passes through the groove, and the second sealing assembly 8 is installed in the groove.

[0029] The connecting assembly 11 includes a connecting head 21 fixedly connected to the other end of the first outer tube 5, and the connecting head 21 abuts against the first sealing assembly 7. A connecting groove 22 is provided on the side of the connecting head 21 away from the first outer tube 5. A choke tube 23 is fixedly connected in the connecting groove 22. A pressing cap 24 is fixedly connected to the outer side of the connecting head 21. The wire rope 4 passes through the axis of the choke tube 23 and the connecting groove 22 along the axis.

[0030] The device is fixed on the wellhead of the gas production well through the connector 21 and the pressure cap 24. At the same time, the choke tube 23 can initially reduce the pressure of the high-pressure gas and liquid inside the gas well, which is convenient for the subsequent sealing operation of the first sealing component 7 and the second sealing component 8.

[0031] Embodiment six: like Figure 1 and Figure 2 As shown, it includes an oil pressure conversion joint 1, in which a first channel 2 and a second channel 3 parallel to the axis are opened, a steel wire rope 4 runs through the first channel 2, joints corresponding to the first channel 2 and the second channel 3 are fixedly connected with a first outer cylinder 5 and a second outer cylinder 6 respectively, a first sealing component 7 is arranged between the inner wall of the second outer cylinder 6 and the steel wire rope 4, a second sealing component 8 is arranged at the connection between the oil pressure conversion joint 1 and the second outer cylinder 6, a hydraulic port 9 is fixedly connected to the side wall of the second channel 3, an adjusting component 10 is arranged at the other end of the second outer cylinder 6, a connecting component 11 is arranged at the other end of the first outer cylinder 5, and the steel wire rope 4 passes through the first sealing component 7 and the second sealing component 8 along the axis.

[0032] A groove is provided at the connection between the oil pressure conversion joint 1 and the second outer tube 6, and the steel wire rope 4 passes through the groove, and the second sealing assembly 8 is installed in the groove.

[0033] The adjustment assembly 10 includes an upper cover 25 fixedly connected to the other end of the second outer cylinder 6. An adjustment groove 26 is provided on the surface of the upper cover 25 away from the second outer cylinder 6. A pressure cap 27 is threadedly connected to the adjusting groove 26, and a cavity is reserved between the pressure cap 27 and the adjusting groove 26. The cavity formed by the pressure cap 27 and the adjusting groove 26 is filled with a filler 28. The wire rope 4 passes through the upper cover 25 and the pressure cap 27 along the axis.

[0034] The regulating assembly 10 in the device is used to block the second outer cylinder 6 to prevent gas leakage. At the same time, the filler 28 in the regulating groove can fill the gap between the upper cover 25 and the steel wire rope 4, always maintaining a good sealing effect to ensure the sealing and stability of the entire device. The gland 27 can squeeze the filler 28 by rotating to make it fully contact with the steel wire rope 4 and reduce the gap.

[0035] This device can change the clamping force of the two sealing components by adjusting the pressure of the liquid or gas input into the hydraulic port 9, and the sealing effect of the sealing component can be known by observing the flow at the first overflow port 18. The sealing force can be flexibly adjusted according to the actual pressure of the wellhead of the gas well, effectively ensuring the sealing effect and reducing the risk of gas and liquid leakage. At the same time, the adjustable clamping force can also avoid excessive wear of the packing, greatly extending the service life of the packing, reducing equipment maintenance costs and replacement frequency, and reducing operation interruption time.

[0036] Working principle: Before using the device, the tool string is first fixed on the wire rope 4, then the electric pump is connected to the hydraulic port 9, the first overflow port 18 is connected to the recovery tank, and a flow meter is installed at the connection between the two, and finally the device is fixed on the wellhead of the gas well through the connecting component 11.

[0037] When performing the sealing operation, the electric pump has a hydraulic port 9 to inject pressure into the second channel 3. After the high-pressure material enters the second channel 3, it is divided into two paths and moves to the first sealing component 7 and the second sealing component 8 respectively. When the high-pressure material enters between the first piston 13 and the oil pressure conversion joint 1, the first piston 13 moves toward the first packing 12 under the action of pressure, squeezing the first packing 12 to make it close to the wire rope 4 for sealing. Similarly, when the high-pressure material enters between the second piston 15 and the oil pressure conversion joint 1, it squeezes the second packing 14 under the action of pressure for sealing.

[0038] When the gas or liquid in the gas production well rises along 4, the pressure is first reduced through the choke tube 23, and then the first sealing component 7 and the second sealing component 8 prevent it from rising further. A small amount of gas passing through the first sealing component 7 will be discharged from the device through the first overflow port 18, and a small amount of gas passing through the second sealing component 8 will be discharged from the device through the second overflow port 19 to prevent leakage.

[0039] The sealing effect of the first sealing assembly 7 and the second sealing assembly 8 can be known by observing the flow of the overflowing gas at the first overflow port 18. When the gas flow is large, the sealing effect is poor, and the pressure injected by the hydraulic port 9 can be appropriately increased to maintain the sealing state. When the gas flow is small, the sealing effect may be too strong, and the pressure injected by the hydraulic port 9 can be appropriately reduced to reduce the loss of the first packing 12 and the second packing 14.

Claims

1. A gas wellhead sealing device, characterized in that: The invention comprises an oil pressure conversion joint (1), wherein a first channel (2) and a second channel (3) parallel to an axis are provided in the oil pressure conversion joint (1), a steel wire rope (4) runs through the first channel (2), a first outer cylinder (5) and a second outer cylinder (6) are fixedly connected to the joints corresponding to the first channel (2) and the second channel (3), a first sealing component (7) is provided between the inner wall of the second outer cylinder (6) and the steel wire rope (4), a second sealing component (8) is provided at the connection between the oil pressure conversion joint (1) and the second outer cylinder (6), a hydraulic port (9) is fixedly connected to the side wall of the second channel (3), an adjustment component (10) is provided at the other end of the second outer cylinder (6), a connecting component (11) is provided at the other end of the first outer cylinder (5), and the steel wire rope (4) passes through the first sealing component (7) and the second sealing component (8) along the axis.

2. The gas wellhead sealing device according to claim 1, characterized in that: A groove is provided at the connection between the oil pressure conversion joint (1) and the second outer cylinder (6), and the steel wire rope (4) passes through the groove. The second sealing assembly (8) is installed in the groove.

3. The gas wellhead sealing device according to claim 2, characterized in that: The first sealing assembly (7) comprises a first packing (12) sleeved on the outside of the steel wire rope (4), and the first packing (12) is closely attached to the inner wall of the first outer tube (5), a first piston (13) is arranged on the side of the first packing (12) close to the oil pressure conversion joint (1), the side of the first piston (13) away from the first packing (12) extends into the first channel (2), and the first piston (13) is connected to the inner wall of the first channel (2) in a dynamic sealing manner.

4. The gas wellhead sealing device according to claim 3, characterized in that: The second sealing assembly (8) comprises a second packing (14) arranged in the groove, and the second packing (14) is closely attached to the inner wall of the groove; a second piston (15) is abutted against a side of the second packing (14) close to the second outer tube (6); an end of the second piston (15) away from the second packing (14) is fixedly connected to a piston rod (16) and extends into the second outer tube (6); a section of the inner wall of the second outer tube (6) close to the oil pressure conversion joint (1) is dynamically sealed with the piston rod (16), and a cavity is left between the remaining part of the inner wall of the second outer tube (6) and the piston rod (16); a plurality of overflow holes (17) are provided on the outer wall of the piston rod (16) and the portion corresponding to the cavity of the second outer tube (6) corresponding to the cavity.

5. The gas wellhead sealing device according to claim 4, characterized in that: A first overflow port (18) is fixedly connected to the side wall of the first channel (2), and the first overflow port (18) is a three-way joint; a second overflow port (19) is correspondingly connected to the cavity section of the second outer cylinder (6); and a straight pipe (20) is fixedly connected between the second overflow port (19) and the first overflow port (18).

6. The gas wellhead sealing device according to claim 1, characterized in that: The connecting assembly (11) comprises a connecting head (21) fixedly connected to the other end of the first outer cylinder (5), and the connecting head (21) is in contact with the first sealing assembly (7); a connecting groove (22) is provided on a side of the connecting head (21) away from the first outer cylinder (5); a choke tube (23) is fixedly connected inside the connecting groove (22); a pressing cap (24) is fixedly connected to the outside of the connecting head (21); and the steel wire rope (4) passes through the axis of the choke tube (23) and the connecting groove (22) along the axis.

7. The gas wellhead sealing device according to claim 1, characterized in that: The adjustment assembly (10) comprises an upper cover (25) fixedly connected to the other end of the second outer tube (6); an adjustment groove (26) is provided on a surface of the upper cover (25) away from the second outer tube (6); a pressure cover (27) is connected to the inner thread of the adjustment groove (26); a cavity is reserved between the pressure cover (27) and the adjustment groove (26); a filler (28) is filled in the cavity formed by the pressure cover (27) and the adjustment groove (26); and the steel wire rope (4) passes through the upper cover (25) and the pressure cover (27) along the axis.

8. A method for sealing a gas wellhead, characterized in that: The gas wellhead sealing device according to any one of claims 5 to 7 is applied, and is specifically implemented according to the following steps: Step 1: Connect the relevant tool string to the wire rope (4) at one end of the connecting assembly (11), connect the electric pump to the hydraulic port (9), connect the first overflow port (18) to the recovery tank, and install a flow meter at the connection between the two; Step 2: Place the tool string into the gas well and then connect it to the wellhead of the gas well via the connecting assembly (11); Step 3: Start the electric pump to inject pressure and seal the wellhead of the gas well; Step 4: Observe the flow meter reading in real time during the sealing process. When the flow meter reading is too large, increase the electric pump injection pressure. When the flow meter reading is too small, reduce the electric pump injection pressure.

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