Wellhead device for large-size single-cylinder twin wells

Abstract

The invention is suitable for the technical field of oil extraction equipment, and provides a large-size single-barrel twin-well wellhead device which is characterized in that a base is provided with a first mounting cavity with a downward opening, a first sealing ring is arranged in a first annular groove, a first injection molding hole is formed in the circumferential wall of the first annular groove, and a glue guide groove is formed in the side, close to the first injection molding hole, of the first sealing ring; a second annular groove is formed in the peripheral wall of the first mounting cavity, a first threaded hole extending to the outer side of the base is formed in the peripheral wall of the second annular groove, the locking piece is in threaded connection with the first threaded hole, the slip head is located in the second annular groove and located at the end of the locking piece, and the locking piece is provided with a first penetrating hole; the limiting bolt penetrates through the first penetrating hole to be connected with the slip head. Filler is injected into the glue guide groove through the first injection molding hole, the sealing ring is extruded to be tightly attached to the waterproof guide pipe, and tight sealing is achieved. In addition, the multiple slip heads clamp the waterproof guide pipe, and reliable connection between the waterproof guide pipe and the base is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil production equipment, and in particular relates to a large-size single-barrel double-well wellhead device. Background Art

[0002] Wellhead device, also known as completion wellhead device, is installed at the wellhead to hang water-proof pipe, casing, tubing and other pipe bodies, and seal the annular space between tubing and casing and each layer of casing. It is generally composed of base, casing head, tubing head, Christmas tree, etc.

[0003] The single-tube double-well riser used in the current offshore platforms is only up to 36 inches, and the single-tube double-well wellhead device with a size larger than 36 inches is still blank. For small-sized risers, the outer diameter size error and roundness error are small, and the connection between the riser and the base can be better achieved through traditional welding methods, and a good seal can be achieved by using the interference fit of the traditional sealing ring and the riser. However, for large-sized risers, the outer diameter size and roundness error are difficult to guarantee, and the traditional welding connection method and sealing method are difficult to apply. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a large-sized single-barrel double-well wellhead device, aiming to solve the problem that the existing welding connection method and sealing method are difficult to apply to large-sized water-proof pipes.

[0005] The embodiment of the present application is implemented as follows: a large-size single-barrel double-well wellhead device, the device comprising: A base, the base is used to be installed at the wellhead of an oil well, the base has a first installation cavity opening downward, the first installation cavity is used to install a water-blocking pipe, and a first annular groove is provided on a peripheral wall of the first installation cavity; A first sealing ring is arranged in the first annular groove, a first injection hole is arranged on a peripheral wall of the first annular groove, and a glue guide groove is arranged on a side of the first sealing ring close to the first injection hole; A plurality of groups of connecting components are arranged at intervals along the circumference of the first mounting cavity, a second annular groove is arranged on the peripheral wall of the first mounting cavity, a first threaded hole extending to the outside of the base is opened on the peripheral wall of the second annular groove, the connecting components include a cava head, a limiting bolt and a locking piece, the locking piece is threadedly connected to the first threaded hole, the cava head is located in the second annular groove and at the end of the locking piece, the locking piece has a first through hole, the limiting bolt passes through the first through hole and is connected to the cava head.

[0006] As a preferred embodiment of the present application, the length of the shaft of the limiting bolt is less than the sum of the circumferential lengths of the second threaded hole and the locking member, but greater than the length of the locking member.

[0007] As a preferred embodiment of the present application, a support ring is further provided in the first annular groove, the support ring abuts against a side of the first sealing ring away from the first injection hole, two support rings are provided at intervals, and the first sealing ring can be deformed and extruded from between the two support rings.

[0008] As a preferred embodiment of the present application, two first annular grooves are arranged at intervals, the first sealing ring is arranged in each of the two first annular grooves, a second injection hole is arranged on the peripheral wall of the first mounting cavity, and the second injection hole is located between the two first annular grooves.

[0009] As a preferred embodiment of the present application, the base is provided with two wellbores, the wellbores are connected to the first installation cavity, the two wellbores are covered with casing heads, the casing heads are connected to the base through flanges, and the sides of the two flanges close to each other have avoidance cutting edges.

[0010] As a preferred embodiment of the present application, a first casing hanger is inserted into the wellbore, the first casing hanger is used to hang the first casing, the first casing hanger is provided with a second sealing ring abutting against the inner wall of the wellbore, the casing head has a second installation cavity connected to the wellbore, the first casing hanger extends into the second installation cavity, and the first casing hanger is also provided with a third sealing ring abutting against the inner wall of the second installation cavity.

[0011] As a preferred embodiment of the present application, an end of the casing head away from the base is connected to a tubing head, a tubing hanger for hanging the tubing is arranged inside the tubing head, a convex ring portion is arranged on the outer periphery of the tubing hanger, a stepped hole for installing the tubing hanger is provided inside the tubing head, the convex ring portion abuts against the stepped surface of the stepped hole to achieve the installation of the tubing hanger, a sealing assembly is arranged on the outer periphery of the tubing hanger, and the sealing assembly is located at the end of the convex ring portion away from the stepped surface.

[0012] As a preferred embodiment of the present application, the sealing assembly includes a first trapezoidal sealing ring and a second trapezoidal sealing ring which are sleeved on the outside of the oil pipe hanger, the first trapezoidal sealing ring and the second trapezoidal sealing ring overlap along the radial portion of the oil pipe hanger, the first sealing ring is located on the outside of the second sealing ring, and when the first trapezoidal sealing ring and the second trapezoidal sealing ring move toward each other in the axial direction, the first trapezoidal sealing ring expands radially and the second trapezoidal sealing ring contracts radially.

[0013] As a preferred embodiment of the present application, a driving ring is arranged on the oil pipe hanger which can be raised and lowered, one end of the first trapezoidal sealing ring away from the second trapezoidal sealing ring abuts against the convex ring portion, and one end of the second trapezoidal sealing ring away from the first trapezoidal sealing ring abuts against the driving ring, and the oil pipe head is provided with a driving screw arranged along its radial direction, the driving screw is threadedly connected to the oil pipe head, and one end of the driving screw close to the convex ring portion has a driving cone surface, and the driving cone surface is used to drive the driving ring to rise and fall.

[0014] As a preferred embodiment of the present application, both of the two oil pipe heads are connected with a Christmas tree, and the two Christmas trees are arranged in a centrally symmetrical manner.

[0015] The embodiment of the present application provides a large-sized single-tube double-well wellhead device, which injects filler between the sealing ring and the peripheral wall of the first annular groove through the first injection hole on the peripheral wall of the first annular groove, squeezes the sealing ring to make it close to the watertight pipe, overcomes the outer diameter error and roundness error of the watertight pipe, and achieves a tight seal. In addition, by driving the locking member to rotate relative to the base, the locking member pushes the cava head to move radially to press the watertight pipe. Multiple groups of the connecting components are arranged at intervals along the circumference of the first mounting cavity, which can ensure that even if the watertight pipe has a larger roundness error, there are still enough cava heads to press the watertight pipe to achieve a reliable connection between the watertight pipe and the base. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A three-dimensional structural diagram of a large-sized single-barrel double-well wellhead device provided in an embodiment of the present application; Figure 2 for Figure 1 A cross-sectional view of an embodiment; Figure 3 for Figure 2 A partial view of the embodiment; Figure 4 for Figure 1 A cross-sectional view of the base at another angle in the embodiment; Figure 5 for Figure 1 A cross-sectional view of the base at another angle in the embodiment; Figure 6 for Figure 2 A partial view of B in the embodiment; Figure 7 for Figure 1 A schematic diagram of the structure of the base and the casing head in the embodiment; Figure 8 for Figure 1 A schematic structural diagram of an embodiment from another perspective.

[0017] In the figure: 100, base; 101, first mounting cavity; 110, first annular groove; 111, first injection hole; 120, second annular groove; 121, first threaded hole; 130, second injection hole; 140, first casing hanger; 141, second sealing ring; 142, third sealing ring; 200, casing head; 210, second installation cavity; 220, second casing hanger; 230, flange; 300, tubing head; 310, stepped hole; 320, tubing hanging tube; 321, convex ring portion; 400. Christmas tree; 510, slip head; 511, second threaded hole; 520, locking member; 521, first through hole; 530, limit bolt; 610, first sealing ring; 611, rubber guide groove; 620, support ring; 710, first trapezoidal sealing ring; 720, second trapezoidal sealing ring; 730, driving ring; 740, limiting ring; 750, driving screw; 800, pressure test hole. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The specific implementation of the present application is described in detail below in conjunction with specific embodiments.

[0020] like Figure 1 and Figure 3 As shown, a large-sized single-barrel double-well wellhead device provided in an embodiment of the present application is provided, and the device includes: a base 100, a first sealing ring 610, and a plurality of connection components.

[0021] The base 100 is used to be installed at the wellhead of an oil well. The base 100 has a first installation cavity 101 opening downward. The first installation cavity 101 is used to install a water-blocking conduit. A first annular groove 110 is provided on the peripheral wall of the first installation cavity 101.

[0022] The first sealing ring 610 is disposed in the first annular groove 110 . A first injection hole 111 is disposed on a peripheral wall of the first annular groove 110 . A glue guiding groove 611 is formed on one side of the first sealing ring 610 close to the first injection hole 111 .

[0023] A plurality of groups of connecting components are arranged at circumferential intervals along the first installation cavity 101, the peripheral wall of the first installation cavity 101 is provided with a second annular groove 120, the peripheral wall of the second annular groove 120 is provided with a first threaded hole 121 extending to the outside of the base 100, the connecting components include a cava head 510, a limiting bolt 530 and a locking member 520, the locking member 520 is threadedly connected to the first threaded hole 121, the cava head 510 is located in the second annular groove 120 and at the end of the locking member 520, the locking member 520 has a first through hole 521, the limiting bolt 530 passes through the first through hole 521 and is connected to the cava head 510.

[0024] In this embodiment, a filler is injected between the first sealing ring 610 and the peripheral wall of the first annular groove 110 through the first injection hole 111 on the peripheral wall of the first annular groove 110, and the first sealing ring 610 is squeezed to make it close to the watertight pipe, thereby overcoming the outer diameter error and roundness error of the watertight pipe and achieving a tight seal. In addition, by driving the locking member 520 to rotate relative to the base 100, the locking member 520 pushes the cava head 510 to move radially to press the watertight pipe. Multiple groups of the connecting components are arranged at intervals along the circumference of the first installation cavity 101, which can ensure that even if the watertight pipe has a larger roundness error, there are still enough cava heads 510 to press the watertight pipe, thereby achieving a reliable connection between the watertight pipe and the base 100.

[0025] like Figure 5 As shown, in some embodiments of the present application, the cava head 510 is in the shape of an arc strip, and the inner arc surface of the cava head 510 is provided with a tooth portion, which can be stuck into the outer peripheral surface of the watertight pipe to achieve a stable connection with the watertight pipe. The outer arc surface of the cava head 510 is provided with a second threaded hole 511, and the tail end of the limit bolt 530 passes through the first through hole 521 of the locking member 520 and is threadedly connected with the second threaded hole 511 of the cava head 510. The size of the bolt head of the limit bolt 530 is larger than the diameter of the first through hole 521, so that the cava head 510 can be prevented from being separated from the locking member 520, and when the locking member 520 is screwed into the first threaded hole 121 of the base 100, the cava head 510 will also be restricted on the base 100 and will not be separated from the base 100, so as to prevent loss. It should be noted that there is no thread in the first through hole 521, and the diameter of the first through hole 521 is slightly larger than the diameter of the shaft of the limit bolt 530.

[0026] In one example of the present application, the watertight pipe is 42 inches, and the connection components are provided with 20 pieces, and the slip heads 510 of the 20 connection components are from the same iron ring. After machining, the iron ring is finely cut into 20 identical slip heads 510 and hardened. In this embodiment, 20 slip heads 510 are provided, and even if the watertight pipe is not round enough or has size deviations, there are still enough teeth to contact and cut into the watertight pipe, providing sufficient bearing capacity.

[0027] In some embodiments of the present application, the length of the limiting bolt 530 is less than or equal to the sum of the circumferential lengths of the second threaded hole 511 and the locking member 520, but greater than the length of the locking member 520. In this embodiment, when the length of the rod of the limiting bolt 530 meets the above conditions, when the limiting bolt 530 is screwed into the second threaded hole 511 of the slip head 510, the two ends of the locking member 520 will be respectively pressed by the slip head 510 and the bolt head of the limiting bolt 530, and the three will be locked into one, and the slip head 510 is restricted in the second annular groove 120 and cannot rotate, so that the locking member 520 cannot rotate either, so that the locking member 520 can be prevented from loosening from the first threaded hole 121. Specifically, when in use, the limiting bolt 530 is not completely screwed into the second threaded hole 511 at the beginning, and the limiting bolt 530 does not clamp the locking member 520. The locking member 520 can rotate in the first threaded hole 121 to push the slip head 510 to move so that the slip head 510 presses the watertight pipe, and then the limiting bolt 530 is rotated to press the locking member 520 to prevent it from loosening. In this way, the limiting bolt 530 can not only prevent the slip head 510 from detaching from the base 100, but also prevent the locking member 520 from loosening, killing two birds with one stone.

[0028] In some embodiments of the present application, an elastic gasket is provided between the bolt head of the limiting bolt 530 and the locking member 520, so that the pre-tightening force can be maintained to prevent the limiting bolt 530 from loosening.

[0029] like Figure 4 As shown, as another preferred embodiment of the present application, a support ring 620 is further provided in the first annular groove 110, the support ring 620 abuts against the side of the first sealing ring 610 away from the first injection hole 111, two support rings 620 are provided at intervals, and the first sealing ring 610 can be deformed and extruded from between the two support rings 620. In this embodiment, the support ring 620 can ensure that the first sealing ring 610 can be stably placed in the first annular groove 110, and can prevent the first sealing ring 610 from being completely extruded out of the first annular groove 110 by the filler.

[0030] like Figure 4As shown, as another preferred embodiment of the present application, two first annular grooves 110 are arranged at intervals, and the first sealing ring 610 is arranged in each of the two first annular grooves 110. The peripheral wall of the first installation cavity 101 is provided with a second injection hole 130, and the second injection hole 130 is located between the two first annular grooves 110. In this embodiment, the two first sealing rings 610 are closely attached to the watertight pipe, so that a closed space is formed between the two first sealing rings 610, and sealant is injected into the closed space to obtain a wider sealing area, which further improves the sealing effect. In addition, the sealant has fluidity before solidification, so that even if the watertight pipe is not round enough or has size deviations, good sealing can still be achieved.

[0031] like Figure 3 and Figure 7 As shown in the figure, as a preferred embodiment of the present application, the base 100 is provided with two wellbores, the wellbores are connected to the first installation cavity 101, and the two wellbores are both covered with casing heads 200, and the casing heads 200 are connected to the base 100 through flanges 230, and the sides of the two flanges 230 close to each other have an avoidance cut edge. It can be understood that the general flange 230 is a complete circle. During installation, a certain distance needs to be spaced between the two sleeve heads to prevent interference between the two full-circular flanges 230. In this embodiment, a part of the side of the two flanges 230 close to each other is cut off to form an avoidance cut edge, which reduces the installation distance required between the two sleeve heads and makes the structure more compact.

[0032] like Figure 2 and Figure 3 As shown, as a preferred embodiment of the present application, a first casing hanger 140 is inserted into the wellbore, the first casing hanger 140 is used to hang the first casing, the first casing hanger 140 is provided with a second sealing ring 141 abutting against the inner wall of the wellbore, the casing head 200 has a second installation cavity 210 connected to the wellbore, the first casing hanger 140 extends into the second installation cavity 210, and the first casing hanger 140 is also provided with a third sealing ring 142 abutting against the inner wall of the second installation cavity 210.

[0033] like Figure 2 As shown, in some embodiments of the present application, a second casing hanger 220 is further disposed in the second installation cavity 210 of the casing head 200, and the second casing hanger is used to hang a second casing.

[0034] In this embodiment, both ends of the first casing hanger 140 extend into the wellbore and the second installation cavity 210 respectively, and provide sealing for the base 100 and the casing head 200 through the second sealing ring 141 and the third sealing ring 142. Compared with the conventional technology, a sealing steel ring is arranged between the two flanges 230, and the sealing steel ring is pressed against the internal pipe body by the excitation bolts radially arranged on the flanges 230, but the scheme of this embodiment does not need to arrange the excitation bolts, so that the two casing heads 200 can be close to each other.

[0035] In some embodiments of the present application, reference Figure 3 As shown, two second sealing rings 141 are provided, and a pressure test hole 800 is provided on the base 100. The pressure test hole 800 on the base 100 is located between the two second sealing rings 141. The sealing effects of the two second sealing rings 141 can be tested through the pressure test hole 800 on the base 100. Two third sealing rings 142 are provided, and a pressure test hole 800 is also provided on the casing head 200. The pressure test hole 800 on the casing head 200 is located between the two third sealing rings 142. The sealing effects of the two third sealing rings 142 can be tested through the pressure test hole 800 on the casing head 200.

[0036] like Figure 2 and Figure 6 As shown, as a preferred embodiment of the present application, the end of the casing head 200 away from the base 100 is connected to the tubing head 300, and the tubing head 300 is provided with a tubing hanger 320 for hanging the tubing, and the outer periphery of the tubing hanger 320 is provided with a convex ring portion 321, and the tubing head 300 has a stepped hole 310 for installing the tubing hanger 320, and the convex ring portion 321 abuts against the stepped surface of the stepped hole 310 to achieve the installation of the tubing hanger 320, and the outer periphery of the tubing hanger 320 is provided with a sealing component, and the sealing component is located at the end of the convex ring portion 321 away from the stepped surface. In this embodiment, the sealing component is located at the end of the convex ring portion 321 away from the stepped surface, and when the tubing hanger 320 is placed in the tubing head 300, the collision and obstruction between the sealing component and the inner wall of the stepped hole 310 of the tubing head 300 can be reduced, and it is easy to replace and maintain.

[0037] like Figure 6As shown, as a preferred embodiment of the present application, the sealing assembly includes a first trapezoidal sealing ring 710 and a second trapezoidal sealing ring 720 sleeved on the outside of the tubing hanger 320, the first trapezoidal sealing ring 710 and the second trapezoidal sealing ring 720 overlap along the radial part of the tubing hanger 320, the first sealing ring 610 is located outside the second sealing ring 141, and when the first trapezoidal sealing ring 710 and the second trapezoidal sealing ring move toward each other in the axial direction, the first trapezoidal sealing ring 710 expands in the radial direction and the second trapezoidal sealing ring contracts in the radial direction. In this embodiment, by the first trapezoidal sealing ring 710 and the second trapezoidal sealing ring 720 moving in the radial direction respectively, it can be ensured that the first trapezoidal sealing ring 710 and the second trapezoidal sealing ring are respectively close to the inner wall of the stepped hole 310 and the outer wall of the tubing hanger 320, thereby improving the sealing effect.

[0038] like Figure 6 As shown, as a preferred embodiment of the present application, a driving ring 730 is provided on the tubing hanger 320 so as to be able to be raised and lowered, one end of the first trapezoidal sealing ring 710 away from the second trapezoidal sealing ring 720 abuts against the convex ring portion 321, and one end of the second trapezoidal sealing ring 720 away from the first trapezoidal sealing ring 710 abuts against the driving ring 730, and the tubing head 300 has a driving screw 750 arranged along its radial direction, the driving screw 750 is threadedly connected to the tubing head 300, and one end of the driving screw 750 close to the convex ring portion 321 has a driving cone surface, and the driving cone surface is used to drive the driving ring 730 to rise and fall. In this embodiment, when the driving screw 750 is rotated, the driving cone surface of the driving screw 750 moves in a direction close to the driving ring 730, and the driving cone surface pushes the driving ring 730 to move, thereby driving the first trapezoidal sealing ring 710 and the second trapezoidal sealing ring 720 to move toward each other along the axial direction. In this way, the seal can be easily activated, and the expansion or contraction of each part of the first trapezoidal seal ring 710 and the second trapezoidal seal can be adjusted in the circumferential direction by a plurality of drive screws 750, so that each part of the two trapezoidal seal rings can be closely attached to the inner wall of the stepped hole 310 or the outer wall of the oil pipe hanging tube 320, thereby improving the sealing effect. In some embodiments of the present application, a limit ring 740 is further provided at one end of the drive ring 730 away from the convex ring portion 321, and the limit ring 740 is used to prevent the drive ring 730 from being separated from the oil pipe hanging tube 320.

[0039] like Figure 8 As shown, as a preferred embodiment of the present application, two of the tubing heads 300 are connected with a Christmas tree 400 , and the two Christmas trees 400 are arranged in a centrally symmetrical manner, which can effectively avoid interference between the two Christmas trees 400 .

[0040] In some embodiments of the present application, a large-size single-barrel double-well wellhead device of the present application can be installed by lowering the watertight pipe into the well, cutting the excess watertight pipe after it is in place, cutting the end face of the watertight pipe to make it horizontal, trimming the bevel, lifting the base 100, keeping it horizontal, adjusting the orientation of the base 100, straightening and centering it, and lowering it steadily so that the first installation cavity 101 of the base 100 is inserted into the watertight pipe, tightening a circle of locking parts 520 and limit bolts 530 on the outer periphery of the base 100, so that the cava head 510 tightly holds the watertight pipe.

[0041] The end of the first casing is fixedly connected to the first casing hanger 140, and lowered into a predetermined position through the wellbore. After both wellbores are lowered into place, cementing and waiting for setting are performed.

[0042] Afterwards, the casing head 200 is installed above the wellbore, and the casing head 200 riser and blowout preventer group are installed, the drill bit is lowered, and the drill is drilled to the designed depth, the second casing is lowered to the predetermined position, cementing and waiting for solidification, the riser and blowout preventer group are removed, the second casing hanger 220 is installed, the redundant second casing is cut and polished, the tubing head 300 is installed above the casing head 200, and the first injection hole 111 and the second injection hole 130 of the base 100 are sealed by injection of glue.

[0043] Install the tubing head 300 to raise the pipe and the blowout preventer group, lower the drill bit, drill to the designed depth with the drill bit, connect the tubing to the tubing hanger 320 through the thread and lower it into the well.

[0044] Install the integral Christmas tree 400.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-size single-barrel double-well wellhead device, characterized in that: The device comprises: A base, the base is used to be installed at the wellhead of an oil well, the base has a first installation cavity opening downward, the first installation cavity is used to install a water-blocking pipe, and a first annular groove is provided on a peripheral wall of the first installation cavity; A first sealing ring is arranged in the first annular groove, a first injection hole is arranged on a peripheral wall of the first annular groove, and a glue guide groove is arranged on a side of the first sealing ring close to the first injection hole; A plurality of groups of connecting components are arranged at intervals along the circumference of the first mounting cavity, a second annular groove is arranged on the peripheral wall of the first mounting cavity, a first threaded hole extending to the outside of the base is opened on the peripheral wall of the second annular groove, the connecting components include a cava head, a limiting bolt and a locking piece, the locking piece is threadedly connected to the first threaded hole, the cava head is located in the second annular groove and at the end of the locking piece, the locking piece has a first through hole, the limiting bolt passes through the first through hole and is connected to the cava head.

2. A large-size single-barrel double-well wellhead device according to claim 1, characterized in that: The length of the shaft of the limiting bolt is less than the sum of the circumferential lengths of the second threaded hole and the locking member, but greater than the length of the locking member.

3. A large-size single-barrel double-well wellhead device according to claim 1, characterized in that: A support ring is also provided in the first annular groove, the support ring abuts against a side of the first sealing ring away from the first injection hole, two support rings are provided at intervals, and the first sealing ring can be deformed and extruded from between the two support rings.

4. A large-size single-barrel double-well wellhead device according to claim 3, characterized in that: Two first annular grooves are arranged at intervals, the first sealing ring is arranged in each of the two first annular grooves, a second injection hole is arranged on the peripheral wall of the first installation cavity, and the second injection hole is located between the two first annular grooves.

5. A large-size single-barrel double-well wellhead device according to claim 1, characterized in that: The base is provided with two wellbores, the wellbores are connected to the first installation cavity, the two wellbores are both covered with casing heads, the casing heads are connected to the base through flanges, and the sides of the two flanges close to each other have avoidance cutting edges.

6. A large-size single-barrel double-well wellhead device according to claim 5, characterized in that: A first casing hanger is inserted into the wellbore, the first casing hanger is used to hang a first casing, the first casing hanger is provided with a second sealing ring abutting against the inner wall of the wellbore, the casing head has a second installation cavity connected to the wellbore, the first casing hanger extends into the second installation cavity, and the first casing hanger is also provided with a third sealing ring abutting against the inner wall of the second installation cavity.

7. A large-size single-barrel double-well wellhead device according to claim 6, characterized in that: The end of the casing head away from the base is connected to a tubing head, a tubing hanger for hanging the tubing is arranged in the tubing head, a convex ring is arranged on the outer periphery of the tubing hanger, a stepped hole for installing the tubing hanger is arranged in the tubing head, the convex ring abuts against the stepped surface of the stepped hole to realize the installation of the tubing hanger, a sealing assembly is arranged on the outer periphery of the tubing hanger, and the sealing assembly is located at the end of the convex ring away from the stepped surface.

8. A large-size single-barrel double-well wellhead device according to claim 7, characterized in that: The sealing assembly includes a first trapezoidal sealing ring and a second trapezoidal sealing ring which are sleeved on the outside of the oil pipe hanger. The first trapezoidal sealing ring and the second trapezoidal sealing ring overlap along the radial part of the oil pipe hanger. The first sealing ring is located on the outside of the second sealing ring. When the first trapezoidal sealing ring and the second trapezoidal sealing ring move toward each other in the axial direction, the first trapezoidal sealing ring expands radially and the second trapezoidal sealing ring contracts radially.

9. A large-size single-barrel double-well wellhead device according to claim 8, characterized in that: A driving ring is arranged on the oil pipe hanging tube so as to be able to be raised and lowered. One end of the first trapezoidal sealing ring away from the second trapezoidal sealing ring abuts against the convex ring portion, and one end of the second trapezoidal sealing ring away from the first trapezoidal sealing ring abuts against the driving ring. The oil pipe head is provided with a driving screw arranged along its radial direction, and the driving screw is threadedly connected with the oil pipe head. One end of the driving screw close to the convex ring portion is provided with a driving cone surface, and the driving cone surface is used to drive the driving ring to be raised and lowered.

10. A large-size single-barrel double-well wellhead device according to claim 9, characterized in that: The two oil pipe heads are both connected with Christmas trees, and the two Christmas trees are arranged in a centrally symmetrical manner.

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