Slip type casing head
Technical Field
The invention relates to the technical field of casing heads, in particular to a slip type casing head.
Background
The casing head is used for fixing a well mouth of a drilling well, connecting a well mouth casing string, supporting the gravity of a technical casing and an oil layer casing, sealing an annular space between layers of pipes, providing transitional connection for installing a blowout preventer and a tubing head and a Christmas tree, and performing construction operations such as mud compensation, mud extrusion, monitoring, balance liquid filling and the like through two side ports on the casing head body.
The casing head is an important connector between the casing and the wellhead, the lower end of the casing head is connected with the surface casing through threads, and the upper end of the casing head is connected with the wellhead or the blowout preventer through a flange or a hoop. The connection between the casing and the casing head can adopt threaded connection (namely a mandrel type casing head) or slip connection (namely a slip type casing head), the casing hanger adopts a rigid and rubber composite sealing structure, and can also adopt metal sealing, so that the sealing performance of the product is enhanced; the casing head still often the supporting design have wear-resisting cover and pressure testing to take out the instrument, make things convenient for taking out of wear-resisting cover and carry out the pressure testing to the casing head, go up flange design has pressure testing, secondary grease injection device, and the valve configuration of casing head flank satisfies different technological demands.
The casing head is typically made of 35 or 42 chromium molybdenum high quality alloy structural steel. And a casing hanger is also arranged in the casing head and used for hanging a casing string with a corresponding specification and sealing the annular space. On which the bop stack is mounted. After the completion of the oil well, a Christmas tree is installed on the casing head. As the drilling process advances, the functional demands placed on the wellhead assembly increase, with a consequent increase in the functional demands placed on casing head production.
The existing casing hanger is mainly divided into a mandrel type and a slip type. Wherein, the requirement of position is accurate when dabber formula casing hanger hangs, the apolegamy degree of difficulty to going into the well casing cluster in the operation has been increased, if the hanger does not have accurate seat to seal in casing head originally internally, unusual operating mode will appear, the subsequent processing is loaded down with trivial details, furthermore, in the work progress, the casing cluster has weightlessness phenomenon in the grout, cause the skew of hanger, make the unable normal clear of construction, influence the construction progress, and dabber formula hanger and bushing have the problem of the excessive nipple joint of dabber, produce thread gluing or other damage phenomena easily, influence the use of product. The slip type hanger has no problems, and the slip type hanger is of the type comprising: the WD type hanger is used for connecting a casing head and a surface casing and enables slip teeth to tightly hold the casing through external force, the W type hanger is a structure for exciting sealing by the self weight of the casing, and the WE type hanger and the G type hanger are structures for manually exciting sealing. In the prior art, the slip type casing head is mainly constructed by assembling an oil pipe cross joint, an oil layer casing, a flange bolt, an injection molding reducing flange, a sealing gasket ring, a slip type hanger, a casing head body and a technical casing. The slip type casing head has the advantages that the height of a casing can be flexibly mastered when the casing is put down, and the slip type hanger can be installed after well cementation operation, so that the risk that the casing is blocked due to the fact that the casing is possibly caused by the time of installing the slip type hanger is greatly avoided, meanwhile, the advantages of freely controlling the height of the casing and the like are achieved, and the slip type casing head is widely popularized.
However, the slips hanger also has the following defects that the installation is difficult due to the complex structure, the well plugging device is required to be disassembled after the sealing operation of the second-level casing head and the third-level casing head is finished, and the sealing performance of the BT sealing ring is influenced by the fact that the annular sealing performance is possibly too high due to casing pressure or the casing is squeezed to be flat during the downhole operation.
In addition, after the slip hanger casing is well consolidated, cement returns to the ground or a certain free section is left, the weight of the casing sitting on the slip hanger is limited, but once the cementing quality is poor or the casing quality is in problem, the weight of the casing is always acted on the slip teeth and is continuously increased, the slip teeth continuously slide downwards, and if the casing strength is not enough, the casing is easily damaged.
The invention discloses a well completion modified casing head, which is a Chinese invention patent with the application number of CN201810265127.4, wherein the general structure of the casing head is combined with the advantages of a mandrel type casing head and a slip type casing head to finally form the well completion modified casing head, and a coupling type casing head structure is used as a basis to form more structures such as modified connection, sealing, installation and the like aiming at complex well completion wellheads, and a plurality of connection and installation plans are pre-designed aiming at well head complexity possibly occurring on site. The casing coupling hanger in the coupling type casing head is changed into a casing body hanger with stronger universality; the advantages of the BT sealing technology are integrated into the special-shaped variable-installation wellhead sealing flange, and sealing combination structures such as special-shaped sealing elements and the like are derived; the variable-assembly wellhead sealing flange and the special-shaped variable-assembly wellhead sealing flange can be applied to variable-assembly structures such as standard flanges, non-standard double flanges, welding flanges, threaded flanges and the like which are common in the well completion process. However, the structure of the well completion variable casing head is complex in design, mainly based on a coupling type casing head structure, and has strong pertinence.
In summary, it is important to provide a slip-type casing head with excellent sealing performance and reasonable structure at low cost.
Disclosure of Invention
In order to solve the technical problem, the invention provides a slip type casing head which comprises a body flange, a casing hanger and an oil casing, wherein the oil casing is fixedly arranged in the casing hanger, the casing hanger is sealed in the body flange, the casing hanger comprises slip teeth and a radial holding device arranged below the slip teeth, and the oil casing is held tightly together with the radial holding device when the slip teeth are pressed down.
During the use, put into the body flange with the casing hanger in, then put into the casing hanger with the oil reservoir sleeve pipe, the kava tooth on the casing hanger slides downwards at the in-process that pushes down of oil reservoir sleeve pipe, hold the oil reservoir sleeve pipe tightly, and simultaneously, at the gliding in-process of kava tooth, radial enclasping device to its below exerts pressure, make radial enclasping device radial extension enclasping oil reservoir sleeve pipe tightly, thereby realize the dual enclasping of kava tooth and radial enclasping device to the oil reservoir sleeve pipe tightly, in addition, the bottom of radial enclasping device is fixed, play limiting displacement to the kava tooth when it is in the pressure state, avoid the excessive gliding of kava tooth to cause the destruction to the oil reservoir sleeve pipe. The radial holding device comprises a first circular ring and a second circular ring, wherein the center of the first circular ring protrudes upwards, the center of the second circular ring protrudes downwards, the outer circular walls of the first circular ring and the second circular ring are connected, the outer circular walls of the first circular ring and the second circular ring are propped against the inner wall of the casing hanger, and the inner diameters of the first circular ring and the second circular ring in a natural extension state are larger than the outer diameter of the oil layer casing. When the radial enclasping device receives the overdraft of the slip, the relative distance between the first ring and the second ring is reduced, and because the outer ring walls of the first ring and the second ring support against the inner wall of the casing hanger, the outer diameter of the radial enclasping device is fixed, the inner diameter is reduced when the radial enclasping device is extruded, and the oil layer casing is held tightly by the support.
Preferably, the radial clasping device is integrally formed, the cross section of the radial clasping device is in a transverse V shape and is symmetrical to form an angle of 30-90 degrees, radial grooves are formed in the first circular ring and the second circular ring, and the radial grooves are formed in the direction from inner holes of the first circular ring and the second circular ring to outer circular walls.
Preferably, the first ring and the second ring are respectively formed, the first ring is provided with a first connecting end, the second ring is provided with a second connecting end, and the first connecting end and the second connecting end are connected through a bolt.
Preferably, the inner annular walls of the first circular ring and the second circular ring are provided with protrusions which incline upwards. The radial frictional force of holding between device and the reservoir casing pipe can be increased to the arch of tilt up, makes and holds more firm, avoids reservoir casing's slip.
Preferably, a compression ring is further arranged between the slip teeth and the radial enclasping device, and the inner diameter of the compression ring is larger than the outer diameter of the oil layer casing. When the clamping ring can make the slips push down, the radial holding device is stressed more uniformly, and the damages to the surface of the radial holding device caused by the slips are avoided.
Preferably, the casing hanger further comprises a slip bowl, a first sealing ring and a second sealing ring,
the slip seat comprises a slip seat body and a cavity,
the slip seat body comprises an upper cylindrical section and a lower circular truncated cone section,
the outer side wall of the upper cylindrical section is cylindrical, a shear pin mounting groove is arranged above the side wall of the upper cylindrical section and communicated with a first threaded hole penetrating through the side wall, a first sealing ring groove is arranged below the outer side wall of the upper cylindrical section,
the lower circular truncated cone section is an inverted circular truncated cone, the lower circular truncated cone section is seated in the body flange, a second sealing ring groove is formed at the seat of the lower circular truncated cone section and the body flange,
the first sealing ring is sleeved in the first sealing ring groove, and the second sealing ring is sleeved in the second sealing ring groove. First sealing washer and second sealing washer can be effectual seal casing hanger, and the second sealing washer sets up in the seat department of sealing of lower round platform section and body flange, can utilize casing hanger's action of gravity, and more effectual sealing to it improves sealed effect.
The cavity is a first cavity, a second cavity and a third cavity from top to bottom in sequence,
the first cavity is in an inverted truncated cone shape, the second cavity is in a cylindrical shape, the third cavity is in a cylindrical shape with a diameter smaller than that of the second cavity,
the first cavity is connected with the slip teeth in a sliding manner, the press ring and the radial holding device are arranged in the second cavity, the diameter of the third cavity is larger than the outer diameter of the oil layer casing pipe,
the outer diameter of the compression ring is the same as the diameter of the second cavity, and the inner diameter of the compression ring is 1-5 mm larger than the outer diameter of the oil layer casing pipe.
Preferably, the slip teeth comprise an inclined section and a vertical section, the outer side wall of the inclined section is an inclined plane matched with the first cavity, a second threaded hole connected with the first threaded hole is arranged above the side wall of the inclined section, the distance from the second threaded hole to the upper surface of the slip teeth is greater than the distance from the first threaded hole to the upper surface of the slip seat, the first threaded hole and the second threaded hole are in threaded connection through a shear pin, after the first threaded hole and the second threaded hole are in threaded connection through the shear pin, the slip teeth are temporarily fixed on the slip seat, the diameter of a circular ring surface formed by the slip teeth is greater than the outer diameter of an oil layer casing pipe, so that the oil layer casing pipe is not subjected to resistance from the slip teeth in the lowering process, when the slip teeth are in the temporarily fixed state, the upper surface of the slip teeth is higher than the distance from one end of the upper surface of the slip seat, and after the oil layer casing pipe is lowered to the, the shear pin is broken by knocking the slip teeth through the hammer, the slip teeth realize free sliding and begin to slide down to hold the oil layer casing tightly,
the vertical section lateral wall is the perpendicular, and the perpendicular is used for exerting pressure to clamping ring and the radial device of holding tightly of slips below, vertical section bottom is equipped with the rubber gasket, under holding tightly the state, slips with the oil reservoir casing butt. The rubber pads prevent the slips from impressing the surface against which they are pressed.
Preferably, the second sealing ring groove is a trapezoidal groove, the size of the notch of the trapezoidal groove is smaller than that of the groove bottom of the trapezoidal groove, and the second sealing ring is an I-shaped sealing ring. Because the second sealing washer recess is located down on the inclined plane of round platform section, consequently install the second sealing washer in the second sealing washer recess and have the landing possibly, influence the construction progress, set the structure of outer narrow interior width with the second sealing washer recess, collocation I shape sealing washer can effectually prevent the landing of second sealing washer simultaneously, improve equipment fixing's stability.
Preferably, the body flange comprises a main through hole, the main through hole comprises a cylindrical first through hole and a cylindrical second through hole with the diameters being sequentially reduced, and an inverted circular truncated cone-shaped third through hole respectively connecting the first through hole and the second through hole, a plurality of fourth through holes communicated with the second through holes are radially arranged below the body flange, a sealing hole is arranged above the body flange,
a sealing element is arranged in the sealing hole, a side flange mounting groove is also arranged below the outer side wall of the body flange, a side flange is arranged in the side flange mounting groove, a steel ring mounting groove is arranged above the body flange, a steel ring is arranged in the steel ring mounting groove,
the second sealing ring groove is arranged on the inclined plane of the lower circular platform section, which is contacted with the third through hole.
Compared with the prior art, the invention has the following beneficial effects:
1. by arranging the radial holding device, the double holding of the slip teeth and the radial holding device on the oil layer casing pipe is realized, and the holding effect on the oil layer casing pipe is improved;
2. when the radial enclasping device is compressed to the limit state, the radial enclasping device is fixed in position, plays a role in limiting, and can effectively avoid damage to an oil layer casing pipe caused by excessive sliding of the slip teeth;
3. a pressure ring is arranged between the slip teeth and the radial enclasping device, and the pressure ring can balance the downward pressure of the slip teeth, so that the radial enclasping device is stressed uniformly;
4. a vertical section is arranged below the slip teeth, and pressure is applied to a pressing ring and a radial holding device below the slip teeth through the vertical section, so that the damage of the tip end of the traditional slip teeth to the contact surface of the slip teeth is avoided;
5. a rubber gasket is arranged below the vertical section of the slip teeth, so that the slip teeth can be further prevented from damaging the surface of a pressing ring below the slip teeth;
6. the first sealing ring and the second sealing ring are respectively arranged on the upper cylindrical section and the lower circular truncated cone section of the slip seat body, so that the sleeve hanger can be effectively sealed, and the second sealing ring is arranged at the seat sealing position of the lower circular truncated cone section and the body flange, so that the gravity action of the sleeve hanger can be utilized, and the sealing effect is improved;
7. the groove of the second sealing ring is designed to be narrow outside and wide inside, and the I-shaped sealing ring is matched, so that the second sealing ring can be effectively prevented from sliding off, and the stability of equipment installation is improved;
8. the slip seat and the slip teeth are temporarily fixed through the shear pins, the downward-placing resistance of the slip teeth to an oil layer casing pipe can be eliminated when the oil layer casing pipe is placed downward at the initial stage of equipment installation, after the temporary fixation is finished, the shear pins are broken by knocking the upper surfaces of the slip teeth through the impact iron, so that the slip teeth can freely slide on the slip seat, the oil layer casing pipe is tightly held, in addition, in the downward-sliding process, the pressure is applied to the radial tightly holding device through the pressure ring, and the dual tightly holding of the slip teeth and the radial tightly holding device to the oil layer casing pipe is realized;
in conclusion, the slip type casing head provided by the invention realizes double holding of the radial holding device and the slip teeth on the oil layer casing, prevents the slip teeth from excessively sliding down to damage the oil layer casing, improves the holding stability and safety, and has excellent sealing effect and high installation efficiency.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic structural view of the radial enclasping device in FIG. 1;
FIG. 3 is a top view of FIG. 2;
FIG. 4 is a schematic diagram of the construction of the casing hanger of FIG. 1;
FIG. 5 is a schematic view of the slip bowl of FIG. 4;
FIG. 6 is a schematic view of the slip elements of FIG. 4;
FIG. 7 is a schematic structural view of the body flange of FIG. 1;
FIG. 8 is a schematic structural view of a radial enclasping device in embodiment 2;
FIG. 9 is a schematic structural view of a radial enclasping device in embodiment 3;
fig. 10 is a plan view of the radial enclasping device in embodiment 4.
Description of reference numerals:
1. a body flange 2, a casing hanger 3, an oil layer casing 4, a sealing element 5 and a steel ring,
11. a first through hole 12, a second through hole 13, a third through hole 14, a fourth through hole 15, a sealing hole 16, a steel ring mounting groove 17, a side flange 18, a side flange mounting groove,
21. a slip seat 22, slip teeth 23, a first sealing ring 24, a second sealing ring 25, a pressing ring 26, a radial holding device 27 and shear pins,
211. the slip bowl body, 212, the cavity,
2111. a first sealing ring groove 2112, a second sealing ring groove 2113, a shear pin mounting groove 2114 and a first threaded hole,
2121. a first cavity, 2122, a second cavity, 2123, a third cavity,
221. the combination of the inclined section, 222, the vertical section,
2211. a second threaded hole, 2221, a rubber washer,
261. a first ring 262, a second ring 263, a bolt 264, a protrusion 265, a radial groove,
2611. first link, 2621, second link.
Detailed Description
The following description of the embodiments of the present invention refers to the accompanying drawings and examples:
it should be noted that the structures, proportions, sizes, and other dimensions shown in the drawings and described in the specification are only for the purpose of understanding and reading the present disclosure, and are not intended to limit the scope of the present disclosure, which is defined by the following claims, and all modifications of the structures, changes in the proportions and adjustments of the sizes and other dimensions which are within the scope of the disclosure should be understood and encompassed by the present disclosure without affecting the efficacy and attainment of the same.
In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
Example 1:
with reference to the accompanying drawings 1-7, a slip type casing head comprises a body flange 1, a casing hanger 2 and an oil casing 3, the oil casing 3 is fixedly arranged in the casing hanger 2, the casing hanger 2 is seated in the body flange 1, the casing hanger 2 comprises slip teeth 22 and a radial enclasping device 26 arranged below the slip teeth 22, and when the slip teeth 22 are pressed down, the radial enclasping device 26 embraces the oil casing 3 together.
The cross section of the radial enclasping device 26 is in a transverse V shape, and comprises a first circular ring 261 and a second circular ring 262, wherein the first circular ring 261 and the second circular ring 262 are connected in an inclined mode, the first circular ring 261 and the second circular ring 262 are integrally formed and are symmetrical to each other to form an angle of 30-90 degrees, the outer circular walls of the first circular ring 261 and the second circular ring 262 abut against the inner wall of the casing hanger 2, and the inner diameter of the first circular ring 261 and the second circular ring 262 in a natural extending state is larger than the outer diameter of the oil layer casing 3.
A pressing ring 25 is further arranged between the slip teeth 22 and the radial enclasping device 26, and the inner diameter of the pressing ring 25 is larger than the outer diameter of the oil layer casing 3.
The casing hanger 2 further comprises a slip bowl 21, a first seal ring 23 and a second seal ring 24,
the slip bowl 21 comprises a slip bowl body 211 and a cavity 212,
the slip seat body 211 comprises an upper cylindrical section and a lower circular truncated cone section,
the outer side wall of the upper cylindrical section is cylindrical, a shear pin mounting groove 2113 is arranged above the side wall of the upper cylindrical section, the shear pin mounting groove 2113 is communicated with a first threaded hole 2114 penetrating through the side wall, a first seal ring groove 2111 is arranged below the outer side wall of the upper cylindrical section,
the lower circular truncated cone section is an inverted circular truncated cone, the lower circular truncated cone section is seated in the body flange 1, a second sealing ring groove 2112 is arranged at the seat of the lower circular truncated cone section and the body flange 1,
the first sealing ring 23 is sleeved in the first sealing ring groove 2111, the second sealing ring 24 is sleeved in the second sealing ring groove 2112,
the cavity 212 is composed of a first cavity 2121, a second cavity 2122 and a third cavity 2123 from top to bottom,
the first cavity 2121 has an inverted circular truncated cone shape, the second cavity 2122 has a cylindrical shape, the third cavity 2123 has a cylindrical shape having a diameter smaller than that of the second cavity 2122,
the first cavity 2121 is slidably connected with the slip teeth 22, the press ring 25 and the radial clasping device 26 are arranged in the second cavity 2122, the diameter of the third cavity 2123 is larger than the outer diameter of the oil casing 3,
the outer diameter of the compression ring 25 is the same as the diameter of the second cavity 2122, and the inner diameter of the compression ring is 5 mm larger than the outer diameter of the oil layer casing 3.
The slip teeth 22 comprise an inclined section 221 and a vertical section 222, the outer side wall of the inclined section 221 is an inclined surface matched with the first cavity 2121, a second threaded hole 2211 connected with the first threaded hole 2114 is arranged above the side wall of the inclined section 221, the distance from the second threaded hole 2211 to the upper surface of the slip teeth 22 is greater than the distance from the first threaded hole 2114 to the upper surface of the slip bowl 21, the first threaded hole 2114 and the second threaded hole 2211 are in threaded connection through a shear pin 27, the shear pin 27 is an M6 international coarse shear pin, the top of the shear pin 27 is provided with a groove (not shown in the figure), the groove width is 2mm, and the groove depth is 2 mm; the length of the cutting part is 4 mm; the thread pitch of the thread is 1 mm;
the outer side wall of the vertical section 222 is a vertical surface, the bottom of the vertical section 222 is provided with a rubber gasket 2221, and the slip teeth 22 are abutted against the reservoir casing 3 in a clasping state.
The second seal ring groove 2112 is a trapezoidal groove, the size of the notch of the trapezoidal groove is smaller than the size of the groove bottom of the trapezoidal groove, and the second seal ring 24 is an i-shaped seal ring.
The body flange 1 comprises a main through hole, the main through hole comprises a cylindrical first through hole 11 and a cylindrical second through hole 12 with the diameters being reduced in sequence, and an inverted circular truncated cone-shaped third through hole 13 respectively connecting the first through hole 11 and the second through hole 12, a plurality of fourth through holes 14 communicated with the second through holes 12 are radially arranged below the body flange 1, a sealing hole 15 is arranged above the body flange 1,
be equipped with sealing member 4 in the sealed hole 15, body flange 1's lateral wall below still is equipped with side flange mounting groove 18, be equipped with side flange 17 in the side flange mounting groove 18, body flange 1 top is equipped with steel ring mounting groove 16, be equipped with steel ring 5 in the steel ring mounting groove 16.
The second seal ring groove 2112 is formed on the inclined surface of the lower circular truncated cone section, which is in contact with the third through hole 13.
In this embodiment, the first ring 261 and the second ring 262 of the radial enclasping device 26 have a thickness of 5 mm, 50CrVA spring steel is selected, and after hot press forming and heat treatment, the spring steel has high strength limit, yield limit, elastic limit and fatigue limit, and simultaneously has high impact toughness, plasticity and yield ratio.
The installation process and the working principle of the slip type casing head in the embodiment are as follows: firstly, the radial holding device 26 is placed into the second cavity 2122 in the slip bowl 21, then the press ring 25 is placed above the radial holding device 26, the slip insert 22 is placed into the first cavity 2121, the second threaded hole 2211 on the slip insert 22 is aligned with the first threaded hole 2114 on the slip bowl 21, the shear pin 27 is installed in the shear pin installation groove 2113, the first threaded hole 2114 and the second threaded hole 2211 are connected through the shear pin 27, so that the slip insert 22 is temporarily fixed on the slip bowl 21, at this time, the upper surface of the slip insert 22 is higher than the upper surface of the slip bowl 21 by a distance, the first seal ring 23 and the second seal ring 24 are respectively installed in the first seal ring groove 2111 and the second seal ring groove 2112, so far, the assembly of the casing hanger 2 is completed, the assembled casing hanger 2 is placed into the body flange 1, then the casing 3 is placed into the casing hanger 2, and after the casing 2113 is lowered to a certain distance, the upper surface of the slip teeth 22 is hit by a hammer with a lifting rope, the shear pin 27 is broken, the inclined section 221 of the slip teeth 22 can slide freely on the inclined plane of the first cavity 2121 in the slip seat body 211, when the slip teeth 22 slide down under the action of the pressure of the oil casing 3, the vertical section 222 of the slip teeth 22 presses the press ring 25, the press ring 25 presses down and transmits the pressure to the radial enclasping device 26, the first ring 261 and the second ring 262 of the radial enclasping device 26 deform under the action of the pressure and compress relatively, the inner diameter is reduced, finally the slip teeth 22 together enclasp the oil casing 3, when the oil casing 3 slides down continuously, the slip teeth 22 continuously move down under the action of the pressure of the oil casing 3, the radial enclasping device 26 enters a limit enclave state, the size of the radial enclasping device 26 is kept stable and cannot be further compressed, and at this time, the radial enclasping device 26 plays a limit role in limiting for the slip teeth 22, the slip elements 22 are held to prevent continued downward sliding of the slip elements 22.
When the casing hanger is disassembled, the slip teeth 22 in the casing hanger 2 are taken out by a tool, after the pressure of the slip teeth 22 disappears, the radial holding device 26 axially extends, the first circular ring 261 and the second circular ring 262 restore to a natural extension state, the inner hole diameter is increased, the casing pipe 3 is separated from the oil layer casing pipe 3, and the oil layer casing pipe 3 can be taken out conveniently.
Example 2:
referring to fig. 8, the slip type casing head of the present embodiment is a further improvement of the radial clasping means 26 over the slip type casing head of embodiment 1. The inner annular walls of the first annular ring 261 and the second annular ring 262 of the radial enclasping device 26 in embodiment 1 are provided with the protrusions 264 which incline upwards, and since the inner annular wall is in direct contact with the outer wall of the production casing 3 in an enclasping state, the friction between the radial enclasping device 26 and the production casing 3 can be increased by the arrangement of the protrusions 264, so that enclasping force is increased, and the production casing 3 is prevented from slipping. The upward slope of the projection 264 may create more resistance as the production casing 3 is pushed down, thereby preventing the production casing 3 from sliding down.
Example 3:
with reference to fig. 9, the slip type casing head of the present embodiment is a further improvement of the radial clasping means 26 on the basis of the slip type casing head of the embodiment 1. The first ring 261 and the second ring 262 of the radial enclasping device 26 in embodiment 1 are separately formed, and a first connection end 2611 is additionally arranged on the outer side of the first ring 261, a second connection end 2621 is additionally arranged on the outer side of the second ring 262, corresponding screw holes are arranged on the first connection end 2611 and the second connection end 2621, and the bolt 263 passes through the screw holes to connect and fix the first connection end 2611 and the second connection end 2621. This structure can eliminate the stress concentration that radial enclasping device 26 produced in compression process outer rampart junction, and stress concentration leads to outer rampart fracture easily to influence the safety of installation stability and production, the first ring 261 and the second ring 262 of radial enclasping device 26 are being connected after the shaping alone respectively, can make the radial life who enclasping device 26 increase, reduce equipment replacement cycle.
In the present embodiment, the first ring 261 and the second ring 262 are connected by the bolt 263, but any other fastening means capable of connecting the first ring 261 and the second ring 262 is applicable to the present embodiment.
Example 4:
the slip type casing head in this embodiment is a further improvement of the radial clasping device 26 on the basis of the slip type casing head in embodiment 1, the first ring 261 and the second ring 262 in embodiment 1 are provided with radial grooves 265, the radial grooves 265 are formed in the direction from the inner holes of the first ring 261 and the second ring 262 to the outer ring wall, the structure can make the radial clasping device 26 more sensitive to pressure, and the inner diameter can be contracted by providing smaller pressure, so that the oil layer casing 3 is clasped.
It should be noted that the radial groove 265 in the present embodiment is also applicable to the first ring 261 and the second ring 262 in embodiments 2 and 3, and the description thereof is omitted.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.