A CO2 flooding oil production wellhead sucker rod sealing device

Abstract

The present invention discloses a CO2 drive oil production wellhead sucker rod sealing device, comprising: a ball seat, an eccentric adjustment member, a pressure cap, a blowout prevention box assembly and a sealing assembly; the lower end of the ball seat is connected to the oil pipe of the wellhead; the outer wall of the lower part of the eccentric adjustment member is a spherical surface and is in rotational contact and sealing with the upper part of the ball seat, and the center of the mounting through hole of the eccentric adjustment member is located at the eccentric position of the ball seat; the pressure cap is connected to the ball seat; the blowout prevention box assembly is connected to the upper part of the eccentric adjustment member; the sealing assembly is connected to the blowout prevention box assembly. In the present invention, driven by the sucker rod, the eccentric adjustment member can float on the ball seat with the sucker rod, so that the blowout prevention box assembly and the sealing assembly can float with the eccentric adjustment member, therefore, the sucker rod will basically not be displaced relative to the central axis of the blowout prevention box assembly and the sealing assembly, the wear between the sucker rod and the blowout prevention box assembly and the sealing assembly is small, thereby reducing the probability of the sucker rod causing eccentric wear and sealing failure on the blowout prevention box assembly.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield development equipment and specifically relates to a CO 2 Sealing device for sucker rod at oil wellhead. Background Art

[0002] At present, almost all shallow oil wells use simple wellheads with simple structures. At the oil production site, multiple simple oil wells (called satellite wells) are usually opened within a certain range for oil production operations. Carbon dioxide flooding to enhance oil recovery and storage technology is increasingly valued as an effective method for resource utilization of greenhouse gases, and various oil fields have successively carried out research and application of this technology. Carbon dioxide is injected into the same layer of multiple satellite wells that need to be driven through special carbon dioxide injection wells. The carbon dioxide injection wells inject carbon dioxide into the oil reservoir to maintain or restore the oil layer pressure stored in the oil reservoir, and then oil is produced through the satellite wells. In the process of injecting carbon dioxide to achieve oil recovery, although some CO 2 It can be stored in the reservoir, but when the injected gas volume reaches a certain level, the CO in the produced gas 2 The content will gradually increase.

[0003] In the use of CO 2 When the oil wells of the drive mode are producing oil, as we all know, the up and down movement of the sucker rod is made by the fan-shaped deflector of the oil production machine (commonly known as the kowtow machine) to do the up and down reciprocating deflection, and the upper end connecting seat of the kowtow machine (commonly known as the donkey head) is flexibly connected to the sucker rod connecting clamp through the wire rope, so as to realize the up and down reciprocating movement of the sucker rod to achieve oil production. Usually in actual operation, there is an error due to the misalignment between the installation center of the pumping unit, i.e. the donkey head, and the center of the oil production wellhead, i.e. the axis of the sucker rod. This leads to displacement (deviation) of the sucker rod relative to the central axis of the blowout preventer and the sealing assembly during the oil production operation, and then there will be greater wear between the sucker rod and the blowout preventer and the sealing assembly, resulting in the phenomenon of partial wear and seal failure of the sucker rod on the blowout preventer and the sealing assembly. At this time, it is necessary to replace the new blowout preventer and the sealing assembly, which shortens the service life of the blowout preventer and the sealing assembly, which not only increases the cost, but also increases the efficiency of accidental safety accidents and reduces safety. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a CO 2 The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] A CO 2 The sealing device of the sucker rod at the oil wellhead comprises: a ball seat, an eccentric adjustment member, a pressure cap, a blowout prevention box assembly and a sealing assembly;

[0006] The lower end of the ball seat is connected to the oil pipe at the wellhead;

[0007] The outer wall of the lower part of the eccentric adjustment member is a spherical surface and is in rotational contact and sealed with the upper part of the ball seat. The eccentric adjustment member is provided with a mounting through hole, which is sleeved on the sucker rod, and the center of the mounting through hole is located at the eccentric position of the ball seat.

[0008] The pressing cap is pressed on the lower part of the eccentric adjusting member and connected to the ball seat;

[0009] The blowout prevention box assembly is sleeved on the sucker rod and connected to the upper part of the eccentric adjustment member;

[0010] The sealing assembly is sleeved on the sucker rod and connected to the blowout prevention box assembly;

[0011] The axis center line of the blowout prevention box assembly and the axis center line of the sealing assembly both coincide with the axis center line of the mounting through hole.

[0012] In one embodiment of the present invention, the blowout prevention box assembly comprises: a blowout prevention box and a sealing seat; the sealing assembly comprises: a first conical spiral cloth-clamped packing, a first packing gland, a mounting seat, a second conical spiral cloth-clamped packing, a second packing gland, a spring and a sealing gland;

[0013] The blowout prevention box has a lower end connected to the upper part of the eccentric adjustment member and an upper end connected to the sealing seat;

[0014] The sealing seat is provided with a first tapered through hole along the axial direction;

[0015] The first conical spiral cloth-cladded packing is arranged in the first conical through hole;

[0016] The first packing gland is pressed on the upper end of the first conical spiral cloth packing;

[0017] The mounting seat has an axial mounting cavity at the lower end and an axial second tapered through hole at the upper end;

[0018] The mounting cavity is in communication with the second tapered through hole;

[0019] The sealing seat is inserted into the mounting cavity;

[0020] The second conical spiral cloth packing is arranged in the second conical through hole;

[0021] The second packing gland is pressed on the upper end of the second conical spiral cloth packing;

[0022] The sealing gland is arranged at the upper end of the mounting seat;

[0023] The spring is arranged in the sealing gland, and its two ends are abutted between the second packing gland and the sealing gland.

[0024] In one embodiment of the present invention, a first positioning wear-resistant bushing is fixedly disposed in the upper end of the mounting through hole.

[0025] In one embodiment of the present invention, a second positioning wear-resistant bushing is provided in the mounting seat;

[0026] The second positioning wear-resistant bushing is located between the mounting cavity and the second tapered through hole.

[0027] Beneficial effects of the present invention:

[0028] The present invention has a sucker rod passing through the sealing assembly, the blowout preventer box assembly, the eccentric adjusting piece and the ball seat. Driven by the sucker rod, the eccentric adjusting piece can float on the ball seat with the sucker rod, thereby making the blowout preventer box assembly and the sealing assembly float with the eccentric adjusting piece. Therefore, the sucker rod will basically not be displaced (deviated) relative to the central axis of the blowout preventer box assembly and the sealing assembly, and the wear between the sucker rod and the blowout preventer box assembly and the sealing assembly is small, thereby reducing the probability of the sucker rod causing eccentric wear and sealing failure on the blowout preventer box assembly, extending the service life of the blowout preventer box assembly, not only reducing the cost, but also reducing the efficiency of accidental safety accidents and improving safety.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a schematic structural diagram of a CO2 flooding oil production wellhead sucker rod sealing device provided by an embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 110-ball seat; 120-eccentric adjustment member; 121-mounting through hole; 130-pressure cap; 140-blowout box assembly; 141-blowout box; 142-sealing seat; 143-first conical through hole; 150-sealing assembly; 151-first conical spiral cloth-clamped packing; 152-first packing gland; 153-mounting seat; 1531-mounting cavity; 1532-second conical through hole; 154-second conical spiral cloth-clamped packing; 155-second packing gland; 156-spring; 157-sealing gland; 160-first positioning wear-resistant bushing; 161-first axial retaining ring; 170-second positioning wear-resistant bushing; 171-second axial retaining ring; 180-grease injection valve; 190-butter nipple. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0034] Embodiment 1

[0035] See also Figure 1 , a CO 2 The sucker rod sealing device for oil wellhead comprises: a ball seat 110, an eccentric adjustment member 120, a pressure cap 130, a blowout prevention box assembly 140 and a sealing assembly 150. The lower end of the ball seat 110 is connected to the oil pipe at the wellhead or other devices connecting the oil pipe. During the oil production process, the sucker rod passes through the sealing assembly 150, the blowout prevention box assembly 140, the eccentric adjustment member 120 and the ball seat 110 in sequence to enter the oil well for oil production.

[0036] The outer wall of the lower part of the eccentric adjustment member 120 is a spherical surface and is in rotational contact and sealed with the upper part of the ball seat 110. The eccentric adjustment member 120 forms a seal with the ball seat 110 through a seal. The eccentric adjustment member 120 is provided with a mounting through hole 121, which is sleeved on the sucker rod, and the center of the mounting through hole 121 is located at the eccentric position of the ball seat 110. In this embodiment, the ball seat 110 is provided with a receiving through hole, the lower end of which is connected to the oil pipe, and the hole wall of the upper part of the receiving through hole is an arc surface that fits the outer wall of the eccentric adjustment member 120, and the eccentric adjustment member 120 can perform spherical rotation at this position of the receiving through hole when the sucker rod is in the sucker rod. The pressure cap 130 is pressed on the lower part of the eccentric adjustment member 120, and the pressure cap 130 is connected to the ball seat 110. The pressure cap 130 is used to limit the eccentric adjustment member 120. Among them, the pressure cap 130 is threadedly connected to the ball seat 110.

[0037] The blowout preventer box assembly 140 is sleeved on the sucker rod, and the blowout preventer box assembly 140 is connected to the upper part of the eccentric adjustment member 120. The sealing assembly 150 is sleeved on the sucker rod, and the sealing assembly 150 is connected to the blowout preventer box assembly 140. The sealing assembly 150 is used to seal the sucker rod on the blowout preventer box assembly 140. The axis of the blowout preventer box assembly 140 and the axis of the sealing assembly 150 are both coincident with the axis of the mounting through hole 121. The center axis of the ball seat 110 is coincident with the center axis of the oil well, and the center axis of the mounting through hole 121 of the eccentric adjustment member 120 is located at the eccentric position of the ball seat 110. Therefore, the center axis of the blowout preventer box assembly 140 and the center axis of the sealing assembly 150 are both located at the eccentric position of the ball seat 110.

[0038] In this embodiment, when oil is produced, the sucker rod is inserted into the sealing assembly 150, the blowout prevention box assembly 140, the eccentric adjustment member 120 and the ball seat 110 to produce oil from the oil well. Driven by the sucker rod, the eccentric adjustment member 120 can float (rotate a certain angle and direction) on the ball seat 110 along with the sucker rod. Movement, so that the blowout preventer box assembly 140 and the sealing assembly 150 can float with the eccentric adjustment member 120, the sucker rod basically will not be displaced (deviated) relative to the central axis of the blowout preventer box assembly 140 and the sealing assembly 150, the center of the sucker rod basically will not deviate from the central axis of the sealing assembly 150 and the blowout preventer box assembly 140, and the wear between the sucker rod and the blowout preventer box assembly 140 and the sealing assembly 150 is small, thereby reducing the probability of the sucker rod causing eccentric wear and sealing failure on the blowout preventer box assembly 140 and the sealing assembly 150, extending the service life of the blowout preventer box assembly 140 and the sealing assembly 150, not only reducing costs, but also reducing the risk of unexpected safety accidents and improving safety.

[0039] In the prior art, due to various errors such as the installation of the pumping unit, the center of the sucker rod will deviate from the center axis of the blowout preventer box and the seal assembly as well as the oil well (the center axis of the blowout preventer box and the center axis of the oil well coincide with each other). Since the center axis of the blowout preventer box and the center axis of the oil well coincide with each other and are fixed, during the oil production operation, the sucker rod will be displaced (deviated) relative to the center axis of the blowout preventer box and the seal assembly during movement, resulting in wear between the sucker rod and the blowout preventer box and the seal assembly, which will cause eccentric wear of the sucker rod on the blowout preventer box and the seal assembly, resulting in seal failure. In the present embodiment, driven by the movement of the sucker rod, the blowout preventer box assembly 140 and the sealing assembly 150 float with the eccentric adjustment member 120 through the first positioning wear-resistant bushing 160 and the second positioning wear-resistant bushing 170, and the central axis of the blowout preventer box assembly 140 and the sealing assembly 150 will basically not be displaced (deviated) relative to the sucker rod, thereby reducing the probability of the sucker rod causing eccentric wear and sealing failure on the blowout preventer box assembly 140 and the sealing assembly 150, extending the service life of the blowout preventer box assembly 140 and the sealing assembly 150, reducing the probability of accidental safety accidents, and improving safety.

[0040] Furthermore, if Figure 1As shown, the blowout preventer box assembly 140 includes: a blowout preventer box 141 and a sealing seat 142. The sealing assembly 150 includes: a first conical spiral cloth-cladded packing 151, a first packing gland 152, a mounting seat 153, a second conical spiral cloth-cladded packing 154, a second packing gland 155, a spring 156 and a sealing gland 157. The lower end of the blowout preventer box 141 is connected to the upper part of the eccentric adjustment member 120, and the upper end of the blowout preventer box 141 is connected to the sealing seat 142. A first conical through hole 143 is provided in the sealing seat 142 along the axial direction. The axial direction of the sealing seat 142 is parallel to the axial direction of the oil well. The first conical spiral cloth-cladded packing 151 is arranged in the first conical through hole 143. The outer diameter of the first conical spiral cloth-cladded packing 151 gradually decreases from top to bottom, and the inner diameter of the first conical through hole 143 matches the outer diameter of the first conical spiral cloth-cladded packing 151. The first packing gland 152 is pressed on the upper end of the first conical spiral cloth packing 151 to press the first conical spiral cloth packing 151 into the first conical through hole 143 .

[0041] An axial mounting cavity 1531 is provided at the lower end of the mounting seat 153, and an axial second tapered through hole 1532 is provided at the upper end of the mounting seat 153. The axial direction of the mounting seat 153 is parallel to the axial direction of the oil well. The lower end of the first packing gland 152 abuts against the upper end of the first tapered spiral cloth packing 151, and the upper end of the first packing gland 152 abuts against the radial inner wall of the upper end of the mounting cavity 1531. The mounting cavity 1531 is connected to the second tapered through hole 1532. The sealing seat 142 is inserted into the mounting cavity 1531 and sealed together. The second tapered spiral cloth packing 154 is arranged in the second tapered through hole 1532. The outer diameter of the second tapered spiral cloth packing 154 gradually decreases from top to bottom, and the inner diameter of the second tapered through hole 1532 matches the outer diameter of the second tapered spiral cloth packing 154. The second packing gland 155 is pressed on the upper end of the second conical spiral cloth packing 154, and the second conical spiral cloth packing 154 is pressed tightly in the second conical through hole 1532. The sealing gland 157 is covered on the upper end of the mounting seat 153 to seal the mounting seat 153. The lower end of the second packing gland 155 abuts against the upper end of the second conical spiral cloth packing 154, and the upper end abuts against the radial inner wall of the sealing gland 157. The spring 156 is arranged in the sealing gland 157, and the two ends of the spring 156 abut between the second packing gland 155 and the sealing gland 157.

[0042] In this embodiment, the first conical spiral cloth packing 151 and the second conical spiral cloth packing 154 are sealing packings made of conical winding cloth-reinforced highly saturated hydrogenated nitrile rubber material, and the sucker rod passes through the center of the first conical spiral cloth packing 151, the first packing gland 152, the second conical spiral cloth packing 154 and the second packing gland 155. During the oil production process, if the part of the center inner side of the first conical spiral cloth packing 151 or the second conical spiral cloth packing 154 that contacts the sucker rod is worn, the part with a larger outer diameter at the upper end will move downward. Since the inner diameter of the conical through hole at the lower side is smaller, the conical spiral cloth packing can shrink toward the center, so that it can fit the sucker rod again and form a seal on the sucker rod again. Therefore, a more durable seal can be formed on the sucker rod, the service life of the sealing assembly 150 is extended, and the sealing effect of the sealing assembly 150 is improved. When the inner hole (rubber seal) of the second conical spiral cloth packing 154 is worn due to the up and down movement with the surface of the sucker rod, resulting in oil leakage from the sucker rod, the second conical spiral cloth packing 154 is pressed down by the spring force, so that the second conical spiral cloth packing 154 is slightly deformed, moved and contracted in the axial and circumferential directions to automatically compensate for the leakage caused by the wear.

[0043] Wherein, the longitudinal section of the tapered through hole is a trapezoid.

[0044] Furthermore, if Figure 1 As shown, a first positioning wear-resistant bushing 160 is fixedly disposed in the upper end of the mounting through hole 121. In this embodiment, the sucker rod can pass through the center of the first positioning wear-resistant bushing 160, and the sucker rod is installed in the mounting through hole 121 through the first positioning wear-resistant bushing 160. Among them, the mounting through hole 121 can be a stepped hole structure, and the diameter of the part of the hole near the upper end is larger. The lower end of the first positioning wear-resistant bushing 160 is against the step of the mounting through hole 121. The upper end of the first positioning wear-resistant bushing 160 can also be provided with a first axial retaining ring 161, which is stuck in the inner wall of the mounting through hole 121 and is used to limit the axial position of the first positioning wear-resistant bushing 160.

[0045] Furthermore, if Figure 1 As shown, a second positioning wear-resistant bushing 170 is arranged in the mounting seat 153. The second positioning wear-resistant bushing 170 is located between the mounting cavity 1531 and the second tapered through hole 1532. In this embodiment, the sucker rod can pass through the center of the second positioning wear-resistant bushing 170. The lower end of the second positioning wear-resistant bushing 170 abuts against the step of the hole at the connection point between the mounting cavity 1531 and the second tapered through hole 1532, and the upper end of the second positioning wear-resistant bushing 170 can also be provided with a second axial retaining ring 171, which is stuck in the inner wall of the hole at the connection point, and is used to limit the axial position of the second positioning wear-resistant bushing 170.

[0046] In a feasible implementation, a grease injection valve 180 is provided on the mounting seat 153, and the grease injection valve 180 is provided at the mounting cavity 1531 and is located on one side of the first stuffing gland 152. A grease nipple 190 is provided on the sealing gland 157, and the grease nipple 190 is close to the upper end of the mounting seat 153. The grease injection valve 180 and the grease nipple 190 are used for filling lubricating oil. Among them, a handle for rotating the pressing cap 130 is provided on the pressing cap 130. The sealing gland 157 is threadedly connected to the mounting seat 153. The mounting seat 153 and the sealing seat 142 are threadedly connected and a seal is formed by a sealing ring. The various components of the wellhead sucker rod sealing device of the present invention form a seal at the connection according to the sealing requirements.

[0047] The installation and adjustment process of the wellhead sucker rod sealing device of the present invention is as follows:

[0048] 1. Separate the sucker rod from the pumping unit according to relevant operating regulations, remove the seal assembly 150, and apply lubricating oil to the surface of the sucker rod at the corresponding position.

[0049] 2. Open the blowout preventer box assembly 140 (turn the switch handle of the blowout preventer box 141 left and right), pass the blowout preventer box assembly 140 and the eccentric adjustment ball assembly (ball seat 110, eccentric adjustment member 120, pressure cap 130) through the sucker rod and tighten them with the main diameter oil pipe thread according to relevant regulations (the first positioning wear-resistant bushing 160 in the eccentric adjustment member 120 must not be damaged when the sucker rod is inserted).

[0050] 3. Install the first conical spiral cloth packing 151 and the first packing gland 152 into the sealing seat 142 at the upper end of the blowout preventer box assembly 140 in sequence, then install and tighten the mounting seat 153 (do not damage the second positioning wear-resistant bushing 170 in the mounting seat 153 when the sucker rod is inserted), and preliminarily tighten the mounting seat 153 with a special hook wrench with a small arm torque.

[0051] 4. Continue to sequentially install the second conical spiral cloth packing 154, the second stuffing gland 155 and the spring 156 into the second conical through hole 1532, and then install the sealing gland 157 and initially tighten it with a special hook wrench with a small arm torque.

[0052] 5. Slightly loosen the pressure cap 130, and then connect and install the sucker rod to the pumping unit according to relevant requirements.

[0053] 6. Open or close the valve of the Christmas tree, turn on the power, start the pumping unit, apply a proper amount of lubricating oil on the pumping rod, observe the movement state, and if it is smooth and without jamming, it is normal. At this time, lightly tighten the pressure cap 130.

[0054] 7. When the pumping unit is pumping oil, first tighten the sealing gland 157 until more oil is visible on the surface of the sucker rod, then tighten the mounting base 153 until the amount of oil adhering to the surface of the sucker rod is reduced, and then continue to tighten the sealing gland 157 until very little oil is visible on the surface of the sucker rod. This completes the adjustment.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0060] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A CO 2 Oil wellhead sucker rod sealing device, It is characterized in that include: A ball seat (110), an eccentric adjustment member (120), a pressure cap (130), a blowout prevention box assembly (140) and a sealing assembly (150); The ball seat (110) has a lower end connected to the oil pipe at the wellhead; The outer wall of the lower part of the eccentric adjustment member (120) is a spherical surface and is in rotational contact and sealed with the upper part of the ball seat (110). The eccentric adjustment member (120) is provided with a mounting through hole (121). The mounting through hole (121) is sleeved on the sucker rod, and the center of the mounting through hole (121) is located at the eccentric position of the ball seat (110). The pressing cap (130) is pressed on the lower part of the eccentric adjusting member (120) and connected to the ball seat (110); The blowout prevention box assembly (140) is sleeved on the sucker rod and connected to the upper part of the eccentric adjustment member (120); The sealing assembly (150) is sleeved on the sucker rod and connected to the blowout prevention box assembly (140); The axis center line of the blowout prevention box assembly (140) and the axis center line of the sealing assembly (150) both coincide with the axis center line of the mounting through hole (121); The blowout prevention box assembly (140) comprises: a blowout prevention box (141) and a sealing seat (142); the sealing assembly (150) comprises: a first conical spiral cloth-clamped packing (151), a first packing gland (152), a mounting seat (153), a second conical spiral cloth-clamped packing (154), a second packing gland (155), a spring (156) and a sealing gland (157); The blowout prevention box (141) has a lower end connected to the upper portion of the eccentric adjustment member (120), and an upper end connected to the sealing seat (142); The sealing seat (142) is provided with a first tapered through hole (143) along the axial direction; The first conical spiral cloth packing (151) is arranged in the first conical through hole (143); The first packing gland (152) is pressed on the upper end of the first conical spiral cloth packing (151); The mounting seat (153) has an axial mounting cavity (1531) at its lower end and an axial second tapered through hole (1532) at its upper end; The installation cavity (1531) is in communication with the second tapered through hole (1532); The sealing seat (142) is inserted into the installation cavity (1531); The second conical spiral cloth-cladded packing (154) is arranged in the second conical through hole (1532); The second packing gland (155) is pressed on the upper end of the second conical spiral cloth packing (154); The sealing gland (157) is arranged on the upper end of the mounting seat (153); The spring (156) is arranged in the sealing gland (157), with two ends abutting between the second stuffing gland (155) and the sealing gland (157); A first positioning wear-resistant bushing (160) is fixedly disposed in the upper end of the mounting through hole (121); A second positioning wear-resistant bushing (170) is arranged in the mounting seat (153); The second positioning wear-resistant bushing (170) is located between the installation cavity (1531) and the second tapered through hole (1532); A second axial retaining ring (171) is provided at the upper end of the second positioning wear-resistant bushing (170), and the second axial retaining ring (171) is inserted into the inner wall of the hole at the connecting point.

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