CN215057235U - Pressure-resistant and corrosion-resistant multistage casing head with interchangeable hangers of different styles - Google Patents

Abstract

The pressure-resistant corrosion-resistant multi-stage casing head capable of interchanging different types of hangers consists of a base, a multi-stage casing head four-way joint, mandrel type casing hangers and slip type casing hangers of different specifications, and a sealing collar, a wing valve, a threaded flange, a pressure gauge assembly, a threaded connector and a sealing element which are matched. A mandrel type casing hanger with an extension neck can be installed in a central hole above the four-way joint of the multi-stage casing head, and a slip type casing hanger can be replaced; the central hole, BT sealing ring and grease injection valve below the casing head four-way joint at each level above the lower level can seal the extended neck above the mandrel type casing hanger at the next level, and can also seal the upper end of the casing clamped by the replaced slip type casing hanger through a matched sealing collar. In addition, the non-metal materials in the sealing element are all fluororubber or high-saturation hydrogenated nitrile rubber. The well is more suitable for being used in complex well conditions and wells with high pressure, high corrosion and high temperature difference.

Description

Pressure-resistant and corrosion-resistant multistage casing head with interchangeable hangers of different styles

Technical Field

The utility model relates to a casing head in oil, natural gas drilling equipment.

Background

The majority of multi-stage casing heads in the existing oil and gas drilling and production equipment are of the type of singly adopting a mandrel type hanger or singly adopting a slip type hanger; only a few multi-stage casing heads adopt a structural form of grading matching of a mandrel type hanger and a slip type hanger; but the hanger does not have the function of interchanging hangers of different styles on site in the central hole of the casing head four-way joint with more than three levels. In the drilling and production processes of more and more ultra-deep wells, extended reach wells, horizontal wells, high-temperature and high-pressure wells, collapsed wells and the like, the abnormal well conditions that the conventional mandrel type hanger is difficult to smoothly install and hang the casing and the slip type hanger needs to be replaced in an emergency can be frequently met. The pressure grade of the multi-stage casing head is high, so that the product volume is large and the cost price is high; if meet abnormal well condition and need wholly change casing head cross, or when wholly changing last level casing head cross and hanger part, will lead to the fact the loss of a large amount of manpower, material resources to can influence the drilling and production progress of oil gas well.

And change the casing hanger of different styles in the four-way centre hole of casing head of the superhigh pressure, must solve two major difficult problems: firstly, the central holes of the casing hangers and the casing head cross joints with different styles and different specifications are subjected to standardized design, and the interchange function of the casing hangers is realized on the premise of ensuring the basic functions of suspension, sealing, dismounting and the like; and the sealing component in the central hole of the upper-level sleeve head four-way joint or the conversion flange is used for sealing the extension neck of the mandrel type hanger with different diameters and the sleeve clamped by the slip type hanger so as to achieve the purpose of complete universality.

Disclosure of Invention

In order to solve the difficult problem, the utility model discloses a technique in groups and new construction carry out the innovative design to current multistage casing head product to reach in the centre bore of multistage casing head each level casing head cross, the homoenergetic reloads the casing hanger of different styles, and improves its sealed reliability, with the purpose that satisfies the super high pressure oil gas well drilling demand.

The utility model consists of a base, a multi-stage casing head four-way joint, mandrel type casing hangers and slip type casing hangers with different specifications, and a sealing neck ring, a wing valve, a threaded flange, a pressure gauge assembly, a threaded connector and a sealing element which are matched; the unique point is as follows: a mandrel type casing hanger with an extension neck can be installed in a central hole above the four-way joint of the multi-stage casing head, and a slip type casing hanger can be replaced; the central hole, BT sealing ring and grease injection valve below the casing head four-way joint at each level above the lower level can seal the extended neck above the mandrel type casing hanger at the next level, and can also seal the upper end of the casing clamped by the replaced slip type casing hanger through a matched sealing collar.

In addition, various sealing washer and gland packing, its non-metallic material be "FKM fluororubber" or "HNBR high saturation hydrogenated nitrile rubber".

Because the utility model discloses a in the centre bore of multistage casing head cross, homoenergetic installation dabber formula casing hanger also homoenergetic changes dress slip formula casing hanger, has improved the commonality of product spare part and should the ability to complicated well conditions, has avoided the loss on manpower, material resources and the time that the former need be changed different types of casing hanger, causes. Because the mandrel type casing hanger with the extension neck and the slip type casing hanger with the sealing collar part are adopted, the upper end and the lower end of the two types of hangers are sealed in multiple ways; besides, the non-metal sealing element is made of fluororubber or high saturated hydrogenated nitrile rubber. Further improves the high pressure resistance and corrosion resistance of the product, and is more suitable for oil and gas wells with complex well conditions, high pressure, high corrosion and high temperature difference.

Drawings

FIG. 1 is a schematic diagram of a combined half-section of a mandrel type casing hanger installed on the right side and a slip type casing hanger installed on the left side in the center of a three-stage casing head four-way joint according to the present invention;

FIG. 2 is an enlarged schematic view of the full cross-sectional structure of the mid-level and low-level mandrel type casing hanger components;

FIG. 3 is an enlarged schematic view of a superior mandrel hanger component in full section;

FIG. 4 is an enlarged schematic view of a half-section of a slip-type casing hanger and mating sealing collar assembly;

FIG. 5 is an enlarged cross-sectional view of the FS and BT seal rings inside and outside the sealing collar at A of FIG. 1;

FIG. 6 is an enlarged schematic view of a horizontal top half-sectional view of a superior wing valve component of a superior casing head cross-piece;

FIG. 7 is an enlarged schematic view of a horizontal top half-section structure of a middle wing valve and a lower wing valve which are matched with a middle tube head and a lower tube head in a four-way mode;

the part names indicated by reference numerals in the drawings are as follows:

1. the device comprises a base, 2, a lower-level casing head four-way joint, 3, a mandrel type casing hanger, 3-1, a casing hanger, 3-2, an O-shaped sealing ring, 3-3, a rectangular sealing ring, 3-4, a pressing ring, 3-5, a round nut, 3-6, a set screw, 4, a middle-level wing valve, 5, a threaded flange, 6, a pipe plug, 7, a middle-level casing head four-way joint, 8, a higher-level casing head four-way joint, 9, a higher-level mandrel type casing hanger, 9-1, a casing hanger, 9-2, a pressing ring, 9-3, a rectangular sealing ring, 9-4, an upper pressing ring, 9-5, an X-shaped metal sealing ring, 9-6, a lower pressing ring, 9-7, a round nut, 9-8, a set screw, 10, a sealing collar, 10-1, a casing, 10-2, a lower-2, a sealing collar, a sealing ring, a sealing, The hydraulic oil-gas seal structure comprises an FS (field stop) seal ring, 11, a slip type casing hanger, 11-1, a slip seat, 11-2, slips, 11-3, a seal ring with a hole, 11-4, a pressing ring, 11-5, an inner hexagon screw, 11-6, a connecting screw, 12, a locking component, 13, an upper-level wing valve, 14, a pressure gauge assembly, 15, a grease injection valve, 16, a BT (BT) seal ring, 17, a seal backing ring, 18, a stud nut, 19, a lower-level wing valve, 20, a small seal backing ring, 21 and a small stud nut.

Detailed Description

The present invention will be further explained with reference to the accompanying drawings:

in fig. 1, the utility model is composed of a base, a multi-layer casing head cross joint, mandrel type casing hangers and slip type casing hangers of different specifications, and a sealing collar, a wing valve, a threaded flange, a pressure gauge assembly, a threaded connector and a sealing element which are matched; wherein: the superposition structure of the three-stage casing head four-way joint and the casing hanger is a common structure of a multi-stage casing head; the superposition structure of the four-way casing head and the casing hanger above four levels is a rare structure and has few customer requirements; if necessary, the design of different pipe diameters can be carried out according to the same casing head four-way joint and the same casing hanger structure. In the utility model, the base, the multi-stage casing head cross joint, the mandrel type casing hangers, the slip type casing hangers and the sealing neck ring with different specifications are taken as basic components, and the structural form is kept unchanged; and spare parts such as wing valve, screw thread formula flange and the manometer assembly that both sides are supporting can make some changes in quantity, installation direction and method according to customer's requirement, nevertheless do not influence the utility model discloses an innovative theme.

The lower casing head cross joint 2 of the utility model is welded on the base 1, is arranged on the cement foundation of the wellhead, and is connected with the surface casing by the taper pipe thread at the lower end of the center hole; the middle-level casing head four-way joint 7 and the upper-level casing head four-way joint 8 are superposed on the lower-level casing head four-way joint 2 and are connected together by a sealing gasket ring 17 and a stud nut 18 which are classified according to size. The left side and the right side of the three-level casing head four-way are connected with a lower-level wing valve 19, a middle-level wing valve 4, an upper-level wing valve 13 and a threaded flange 5 by using a small sealing gasket ring 20 and a small stud nut 21; on the outer side of the threaded flange 5, a pressure gauge assembly 14 can be arranged for measuring the pressure between the sleeves; the pipe plug 6 can be used for plugging or connecting external pipelines. In central holes above a lower-level casing head four-way joint 2, a middle-level casing head four-way joint 7 and a higher-level casing head four-way joint 8, a mandrel type casing hanger 3 and a higher-level mandrel type casing hanger 9 which have better performance and different drift diameters are installed preferentially; and different specifications of slip-type casing hangers 11 which can be interchanged with the three-stage mandrel-type casing hangers are collocated according to a predetermined proportion. The middle-level casing head four-way 7 and the upper-level casing head four-way 8, a center hole below the middle-level casing head four-way 7, two grease injection valves 15 and a BT sealing ring 16 can seal an extended neck above the mandrel type casing hanger 3 of the next level, and can also seal the upper end of a casing clamped by the replaced slip type casing hanger 11 through a matched sealing collar 10. Mandrel type casing hangers 3 and 9 or slip type casing hangers 11 arranged in the three-stage casing head four-way joint are all pressed and fixed by locking parts 12 uniformly distributed above the three-stage casing head four-way joint.

In the utility model, the center of the lower casing head cross 2 is a through step hole, and the upper step hole can be respectively provided with a large-diameter mandrel casing hanger 3 or a slip casing hanger 11; the stepped hole at the lower part is provided with a taper pipe thread connected with the surface sleeve. A large flange is arranged above the lower-stage casing head four-way joint 2, and uniformly distributed stud holes and a trapezoidal cushion ring groove are processed on the large flange and are connected with a middle-stage casing head four-way joint 7; on the circumference of the upper flange, a plurality of uniformly distributed horizontal step holes with threads at both ends and communicated with the central hole are processed, and locking parts 11 with thread pressing caps and sealing fillers are arranged in the holes and used for pressing the casing hanger in the central hole. The middle lower part of the lower casing head cross 2 is a hollow cylinder with the same diameter, and two planes are processed on the two corresponding sides of the cylinder; the middle parts of the two planes are respectively provided with a bypass hole communicated with the central hole, and the outer openings of the bypass holes of the two planes are respectively provided with a plurality of uniformly distributed threaded blind holes and a trapezoidal gasket ring groove for connecting parts such as a lower-level wing valve 19 and the like.

The center of the middle-stage casing head four-way joint 7 is a through step hole, and a mandrel casing hanger 3 or a slip casing hanger 11 with a medium diameter can be respectively installed in the step hole above the middle-stage casing head four-way joint; the lower stepped hole is a cylindrical hole for accommodating the upper extending neck of the next-stage mandrel type casing hanger 3, two rectangular grooves are cut on the hole wall of the cylindrical hole, and a BT sealing ring 16 is arranged in each rectangular groove. A neck flange is arranged above the middle-level casing head four-way joint 7, and uniformly distributed stud holes and a trapezoidal cushion ring groove are processed on the neck flange and are connected with a higher-level casing head four-way joint 8; on the circumference of the flange with neck, several uniformly distributed horizontal step holes with screw threads at both ends and communicated with central hole are made, and in the holes several locking components 11 with screw thread pressing cap and sealing filler are mounted, and can be used for tightly pressing casing hanger in the central hole. The middle of the middle-stage casing head four-way joint 7 is a hollow cylinder with the same diameter, and two corresponding sides of the cylinder are processed into planes; the middle parts of the two planes are respectively provided with a bypass hole communicated with the central hole, and the outer openings of the bypass holes of the two planes are respectively provided with a plurality of uniformly distributed threaded blind holes and a trapezoidal gasket ring groove for connecting parts such as a middle-stage wing valve 4. A large flange is arranged below the middle-stage casing head four-way joint 7, and uniformly distributed stud holes and a trapezoidal cushion ring groove are processed below the large flange and are connected with the lower-stage casing head four-way joint 2; four horizontal step holes with threads at inlet ends and communicated with the rectangular groove in the central hole are symmetrically processed on the periphery of the large flange one above the other, and grease injection valves 15 are arranged at the hole openings and used for injecting plastic sealing grease and extruding BT sealing rings 16 to seal an extension neck above the next-stage mandrel type casing hanger 3.

The center of the upper-level casing head four-way joint 8 is also a through step hole, and an upper-level mandrel casing hanger 9 or a slip casing hanger 11 with smaller diameter can be respectively installed in the step hole above the upper-level casing head four-way joint; the stepped hole below is a cylindrical hole for accommodating the extending neck above the next-stage mandrel type casing hanger 3, two rectangular grooves are also cut on the hole wall of the cylindrical hole, and a BT sealing ring 16 is respectively arranged in each rectangular groove. The upper and lower parts of the upper casing head four-way joint 8 are respectively provided with a neck flange, and both end faces of the upper and lower neck flanges are respectively provided with a uniformly distributed stud hole and a trapezoidal cushion ring groove for connecting with the outside; a plurality of uniformly distributed horizontal step holes with threads at two ends and communicated with the central hole are processed on the periphery of the upper flange with a neck, and locking parts 11 with thread pressing caps and sealing fillers are arranged in the holes and used for pressing the casing hanger in the central hole; four horizontal step holes with threads at inlet ends and communicated with the rectangular groove in the central hole are symmetrically processed on the periphery of the flange with the neck at the lower part, and grease injection valves 15 are arranged at the hole openings and used for injecting grease to extrude a BT sealing ring 16 for sealing. The middle of the upper casing head cross 8 is a hollow cylinder with the same diameter, and two corresponding sides of the cylinder are processed into planes; the middle parts of the two planes are respectively provided with a bypass hole communicated with the central hole, and the outer openings of the bypass holes of the two planes are respectively provided with a plurality of uniformly distributed threaded blind holes and a trapezoidal gasket ring groove for connecting parts such as a superior wing valve 13 and the like.

In fig. 2, the mandrel type casing hanger 3 used in the lower casing head cross 2 and the middle casing head cross 7 of the present invention is composed of a casing hanger 3-1, an O-shaped seal ring 3-2, a rectangular seal ring 3-3, a clamp ring 3-4, a round nut 3-5 and a set screw 3-6; the lower end of the hanger is sealed by adopting a double sealing structure of an O-shaped sealing ring 3-2 and a rectangular sealing ring 3-3. The casing hanger 3-1 is a hollow cylindrical body with a thick middle part and thin two ends, the center of the cylindrical body is a through stepped hole, two ends of the stepped hole are both processed into taper pipe threads, the taper pipe threads at the lower end are used for connecting a suspended casing pipe, and the taper pipe threads at the upper end are used for connecting a drill rod so as to assemble and disassemble the hanger; the upper end and the lower end of the columnar body are both smooth extension necks, and the extension neck at the upper end is used for extending into a central hole of the upper-stage casing head four-way joint for sealing so as to improve the high-pressure resistance of a casing head product; the middle of the cylindrical body is a cylinder with large diameter, the upper edge of the cylinder is a large chamfer, and the cylinder is matched with the locking parts 12 in the lower-stage casing head four-way 2 and the middle-stage casing head four-way 7 for compressing and fixing; a groove is cut in the middle of the cylinder, and an O-shaped sealing ring 3-2 is arranged in the groove and used for enhancing the sealing performance of the cylinder; a cylinder and a screw cylinder with reduced diameters are arranged below the middle cylinder, and a rectangular sealing ring 3-3, a pressing ring 3-4 with a large chamfer, a round nut 3-5 and a set screw 3-6 are sequentially arranged; and a large chamfer on the pressing ring 3-4 is matched with a step chamfer in the central hole of the lower-stage casing head four-way 2 and the central hole of the middle-stage casing head four-way 7 to hang the casing, and the gravity of the hanging casing is converted into the pressing force of the rectangular sealing ring 3-3.

In fig. 3, the upper mandrel type casing hanger 9 used in the upper casing head cross 8 of the present invention is composed of a casing hanger 9-1, a pressing ring 9-2, a rectangular sealing ring 9-3, an upper pressing ring 9-4, an X-shaped metal sealing ring 9-5, a lower pressing ring 9-6, a round nut 9-7, and a set screw 9-8; the lower end of the hanger is mainly sealed by adopting a double sealing structure of a rectangular sealing ring 9-3 and an X-shaped metal sealing ring 9-5. The casing hanger 9-1 is also a hollow cylindrical body with a thick middle part and thin two ends, the center of the cylindrical body is a through stepped hole, and the two ends of the stepped hole are both processed into conical pipe threads which are respectively used for connecting a suspended casing pipe and a drill rod; the upper end and the lower end of the columnar body are both smooth extension necks, and the extension neck at the upper end is used for extending into a central hole of the upper-level part for sealing; the middle of the columnar body is a large-diameter cylinder, the upper surface and the lower surface of the cylinder are respectively a cylinder and a screw cylinder with reduced diameters, a rectangular sealing ring 9-3, a large-chamfer pressing ring 9-2, a round nut 9-7 and a set screw 9-8 are sequentially arranged on the cylinder, and the large-chamfer pressing ring 9-2 is matched with a locking component 12 in a superior casing head four-way joint 8 for pressing, fixing and sealing; the lower part is sequentially provided with an upper extrusion ring 9-4, an X-shaped metal sealing ring 9-5, a lower extrusion ring 9-6, a round nut 9-7 and a set screw 9-8; the large chamfer angle on the lower extrusion ring 9-6 is matched with the step chamfer angle in the central hole of the upper casing head four-way joint 8, so that the casing is suspended, and the gravity of the suspended casing is converted into the pressing force of the X-shaped metal sealing ring 9-5.

In fig. 4, the utility model provides a slips formula casing hanger 11 chooses for use the general WE type slips formula casing hanger structure in the market, and its essential element includes: the device comprises a slip seat 11-1, slips 11-2, a perforated sealing ring 11-3, a pressing ring 11-4, an inner hexagon screw 11-5 and a connecting screw 11-6; the lower ends of the clamped sleeve and the hanger are actively sealed by connecting and pressing the pressing ring 11-4 and the sealing ring 11-3 with holes through the inner hexagon screw 11-5 and the locking part 12 in the sleeve head four-way joint so as to ensure the sealing reliability. The slip seat 11-1 is a hollow cylindrical part with a thick upper part and a thin lower part, and a plurality of uniformly distributed threaded blind holes are processed on the upper end surface of the slip seat and are used for connecting a sealing ring 11-3 with a hole, a pressing ring 11-4 and an inner hexagon screw 11-5; the center of the conical body is processed into a step hole which takes an inverted cone as a main part, and the step hole is matched with a slip 11-2 of the conical body to generate radial clamping force; the transition large chamfer is arranged at the joint of the upper thick cylindrical body and the lower thin cylindrical body, and is matched with the step chamfer in the central hole of the four-way of the casing head to hang the casing; a plurality of radial through holes are uniformly distributed on the thinner cylinder below so as to fix the slips 11-2 which are cut into a plurality of pieces by a screw rod; when the slip type casing hanger 11 is used on site, a casing is clamped from the radial direction, so the slip seat 11-1 is symmetrically cut into two halves, two opposite step holes and threaded blind holes are symmetrically processed at the tangent line and the cut part of the circumference under the thick cylinder of the slip seat, and the two opposite step holes and the threaded blind holes are combined into a whole by using a connecting screw 11-6. The center of the slip 11-2 is a sawtooth-shaped through hole which is used for clamping a corresponding sleeve; the upper part of the periphery is processed into an arc body, the middle lower part is processed into a cone, and the cone is symmetrically cut into 6-4 pieces according to the diameter of the clamping sleeve so as to improve the clamping effect; 6-4 radial threaded holes, namely one hole for each slip, are symmetrically processed below the cone of the slips 11-2, and the sliced slips 11-2 and the slip seat 11-1 are positioned and connected by a screw rod before use, so that the slips are convenient to package, transport, install and use. The perforated sealing ring 11-3 is an annular non-metal part, the upper plane and the lower plane of the perforated sealing ring are provided with screw holes which are uniformly distributed, the sealing surfaces at the inner side and the outer side are provided with an upper arc bulge and a lower arc bulge, and the double sealing effect can be generated under the action of pressure. Also, the clamp ring 11-4 is cut symmetrically in two pieces, and the resilient apertured seal ring 11-3 is cut with a bevel, again for field assembly.

In fig. 4 and 5, each slip type casing hanger 11 is fitted with a sealing collar 10 having an inner diameter matching the outer diameter of the casing being held; the sealing collar 10 consists of a collar sleeve 10-1 and an FS sealing ring 10-2; the collar sleeve 10-1 is a hollow cylinder, two grooves are processed above a smooth central hole of the collar sleeve, and an FS sealing ring 10-2 is respectively arranged in each groove; under its cylinder, processing has 2 ~ 4 radial through-holes to the dismantlement of sealed neck ring 10 is convenient for. The main body part of the FS sealing ring 10-2 is made of non-metal materials, and two elastic steel wire rings are respectively embedded at two raised shoulders of the FS sealing ring so as to enhance the deformation resistance of the FS sealing ring.

In fig. 6 and 7, the multi-stage casing head is in use, the working pressure is different due to different depths of the casings of the connected layers, and the pressure grade is in a high-low state. Therefore, the upper-level wing valve 13 matched with the upper-level casing head four-way valve 8 adopts a manual rising stem flat valve which is driven by a ball screw pair and is provided with a tail stem and a sand prevention plate, so as to reduce the operation resistance of the valve and the sand blocking phenomenon during fracturing operation; the middle-level wing valve 4 and the lower-level wing valve 19 which are matched with the lower-level casing head four-way valve 2 and the middle-level casing head four-way valve 7 both adopt manual open-lever flat valves which are driven by trapezoidal thread pairs and have no tail levers and sand control plates, so that the production cost is reduced; the lower level wing valve 19 may also be implemented with an 8-shaped drive hand wheel to accommodate the tight space below the ground surface.

The utility model discloses used O type sealing washer 3-2, rectangle sealing washer 3-3, 9-3 and porose sealing washer 11-3 in the casing hanger, used FS sealing washer 10-2 in the sealed neck ring 10, used BT sealing washer 16 and used sealing filler in the locking part 11 in the casing head cross, its non-metallic material is "FKM fluororubber" or "HNBR high saturation hydrogenation butadiene acrylonitrile rubber" to the corrosion resisting property of multistage casing head has been improved.

Claims (7)

1. A pressure-resistant corrosion-resistant multi-stage casing head with interchangeable hangers of different styles consists of a base, a multi-stage casing head four-way joint, mandrel type casing hangers of different specifications, a slip type casing hanger, a sealing collar, a wing valve, a threaded flange, a pressure gauge assembly, a threaded connecting piece and a sealing piece which are matched; the method is characterized in that: a mandrel type casing hanger with an extension neck can be installed in a central hole above the four-way joint of the multi-stage casing head, and a slip type casing hanger can be replaced; the central hole, BT sealing ring and grease injection valve below the casing head four-way joint at each level above the lower level can seal the extended neck above the mandrel type casing hanger at the next level, and can also seal the upper end of the casing clamped by the replaced slip type casing hanger through a matched sealing collar.

2. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: the mandrel type casing hanger used in the lower casing head cross joint and the middle casing head cross joint consists of a casing hanger, an O-shaped sealing ring, a rectangular sealing ring, a pressing ring, a round nut and a set screw; the lower end of the hanger is sealed mainly by adopting a double sealing structure of an O-shaped sealing ring and a rectangular sealing ring; the casing hanger is a hollow cylindrical body with a thick middle part and thin two ends, the center of the cylindrical body is a through stepped hole, and two ends of the stepped hole are both processed into taper pipe threads.

3. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: the upper mandrel type casing hanger used in the upper casing head four-way joint consists of a casing hanger, a pressing ring, a rectangular sealing ring, an upper extrusion ring, an X-shaped metal sealing ring, a lower extrusion ring, a round nut and a set screw; the lower end of the hanger is sealed mainly by adopting a double sealing structure of a rectangular sealing ring and an X-shaped metal sealing ring; the casing hanger is also a hollow cylindrical body with a thick middle part and thin two ends, the center of the cylindrical body is a through stepped hole, and two ends of the stepped hole are both processed into taper pipe threads.

4. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: the used slip type casing hanger is a WE type slip type casing hanger structure which is universal on the market, and the main parts of the hanger comprise: the device comprises a slip seat, slips, a sealing ring with holes, an inner hexagon screw, a pressing ring and a connecting screw; the holed sealing ring is an annular non-metal part, screw holes are uniformly distributed on the upper plane and the lower plane of the holed sealing ring, and an upper arc-shaped bulge and a lower arc-shaped bulge are respectively arranged on the sealing surfaces of the inner side and the outer side.

5. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: each slip type casing hanger is matched with a sealing collar with the inner diameter matched with the outer diameter of the clamped casing; the sealing collar consists of a collar sleeve and an FS sealing ring; the collar sleeve is a hollow cylinder, two grooves are processed above a smooth central hole of the collar sleeve, and FS sealing rings are respectively arranged in the grooves; 2-4 radial through holes are processed below the cylinder; the main body part of the FS sealing ring is made of non-metal materials, and two elastic steel wire rings are respectively embedded at two raised shoulders of the FS sealing ring.

6. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: the upper-level wing valve matched with the upper-level casing head four-way valve adopts a manual rising stem flat valve which is driven by a ball screw pair and is provided with a tail stem and a sand-proof plate; the middle-level wing valve and the lower-level wing valve which are matched with the lower-level casing head four-way valve and the middle-level casing head four-way valve both adopt manual open-stem flat valves which are driven by trapezoidal thread pairs and have no tail stems and no sand control plates.

7. The pressure resistant, corrosion resistant multi-stage casing head of an interchangeable different style hanger of claim 1 wherein: the O-shaped sealing ring, the rectangular sealing ring and the sealing ring with holes are used in the casing hanger, the FS sealing ring is used in the sealing collar, the BT sealing ring is used in the casing head four-way joint, the sealing filler is used in the locking component, and the non-metallic materials are FKM fluororubber or HNBR high-saturation hydrogenated nitrile rubber.

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