Oil and gas production wellhead casing head

Abstract

The utility model relates to an oil and gas production wellhead casing head which comprises a casing head body, a mandrel type casing hanger and a metal sealing assembly. The casing head body is coaxially arranged outside the mandrel type casing hanger in a sleeving manner; the mandrel type casing hanger comprises a first connecting part, a second connecting part and a third connecting part which are sequentially connected and communicated with one another; the first connecting part extends out of the casing head body and is connected with a tubing head; the second connecting part is arranged in the casing head body, the second connecting part is in sealing connection with the casing head body through a metal sealing assembly, and the metal sealing assembly adopts combined sealing of metal and rubber; the third connecting part is in threaded connection with a production sleeve; the outer diameter of the first connecting part is larger than that of the production sleeve connected with the third connecting part. The mandrel type casing hanger is adopted, the sizes of the two ends of the mandrel type casing hanger can be customized according to actual casings and tubing heads, the mandrel type casing hanger can adapt to casings of different sizes, sealing connection with the tubing heads is achieved, and the cost of spare parts and the workload of disassembly and assembly are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of wellhead devices for oil and gas production wells, and in particular relates to a casing head for oil and gas production wells. Background Art

[0002] The casing head is a wellhead sealing device component installed on the upper end of the surface casing on the formation surface and forms a reliable connection with the casing. It is used to suspend the surface casing and seal the casing annulus. The tubing head is installed above the topmost casing head and is sealed with a metal gasket. Through the flange bolts and nuts distributed along the circumference, a reliable fastening connection is formed to suspend the tubing and seal the annulus between the tubing and the casing. The tubing head and the connecting casing head need to be connected through the casing to form a sealed channel for the tubing and casing.

[0003] In the actual oil or gas production process, the size of the production casing is not always fixed. For cost considerations, reducing the diameter of the production casing can directly reduce the cost of the casing, and it is easier to reach the formation fracturing pressure after the diameter of the production casing is reduced, thereby reducing the production cost. However, the inner diameter of the connection hole of the original tubing head is larger than the outer diameter of the reduced diameter production casing, resulting in the inability to seal the connection between the two, and the connection structure of the casing head and the tubing head connected to the casing head is also difficult to adapt. To solve this problem, it is necessary to set a series of tubing heads and casing heads of different sizes, and then connect the tubing heads, casing heads and casings of the same size one by one to achieve matching with the size of the production casing, which increases the cost of spare parts and the workload of disassembly and assembly. Therefore, a casing head for oil and gas production wells that can adapt to casings of different sizes is needed. Utility Model Content

[0004] In order to solve the above problems existing in the prior art, the utility model provides a casing head for oil and gas production wells. The technical problem to be solved by the utility model is achieved through the following technical solutions:

[0005] The utility model provides a casing head for oil and gas production wellhead, comprising: a casing head body, a mandrel-type casing hanger and a metal sealing component;

[0006] The casing head body is coaxially sleeved outside the casing mandrel type pipe hanger;

[0007] The mandrel-type casing hanger comprises: a first connection part, a second connection part and a third connection part which are sequentially connected and communicated with each other;

[0008] The first connecting portion extends out of the casing head body and is connected to the tubing head;

[0009] The second connection portion is disposed in the casing head body, and the second connection portion is sealed and connected to the casing head body through the metal sealing assembly;

[0010] The third connection portion is threadedly connected to the production casing;

[0011] The outer diameter of the first connecting portion is greater than or equal to the outer diameter of the production casing connected to the third connecting portion;

[0012] The metal sealing component adopts a combined seal of metal and rubber.

[0013] In one embodiment of the present invention, the first connection part, the second connection part and the third connection part are connected to each other through a through hole, and the diameter of the through hole is greater than or equal to the inner diameter of the production casing. In one embodiment of the present invention, the third connection part is provided with a connecting internal thread, and the connecting internal thread matches the thread of the production casing.

[0014] In one embodiment of the present invention, a lifting thread is provided between the first connection portion and the second connection portion.

[0015] In one embodiment of the utility model, the metal sealing assembly comprises: a top screw, a pressure ring and a metal sealing ring;

[0016] The central axis of the top screw is perpendicular to the central axis of the mandrel type casing hanger;

[0017] The top screw is threadedly connected to the casing head body; a pressing ring is arranged between one end of the top screw and the mandrel-type casing hanger;

[0018] The metal sealing ring is arranged below the pressing ring.

[0019] In one embodiment of the present invention, the metal sealing assembly further comprises: at least two rubber sealing rings; the at least two rubber sealing rings are arranged below the metal sealing ring and are sequentially sleeved on the mandrel type casing hanger at intervals.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The utility model of the casing head for oil and gas production wellhead realizes the sealing connection with the tubing head by thickening the extension neck extending from the upper end of the mandrel-type casing hanger, that is, by thickening the first connection part extending from the casing head body; the mandrel-type casing hanger is arranged in the casing head body, and realizes the sealing connection with the casing head body through the metal sealing assembly in which metal and rubber work together, and the third connection part of the mandrel-type casing hanger is provided with an internal thread for connecting the production casing. Since the mandrel-type casing hanger is independently designed and manufactured, the dimensions of its two ends can be customized according to the actual production casing and the connection dimensions of the connected tubing head, and the outer diameter specification size of the first connection part located at the top is larger than the size of the production casing connected to the third connection part located at the bottom, so that it can adapt to production casings of different specifications and sizes, thereby realizing the sealing connection of the tubing head, reducing the variety cost of the tubing head spare parts and the workload of disassembly and assembly. At the same time, by increasing the outer diameter of the first connection part, its wall thickness is also increased, thereby enhancing the internal pressure resistance of the extension neck of the mandrel-type casing hanger.

[0022] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural schematic diagram of a casing head for a gas wellhead provided by an embodiment of the utility model;

[0024] Figure 2 It is a partial enlarged view A of a casing head of a gas production wellhead provided by an embodiment of the utility model.

[0025] Icons: 100-casing head body; 200-mandrel type casing hanger; 210-first connection part; 220-second connection part; 230-third connection part; 240-lifting thread; 300-metal sealing assembly; 310-top screw; 320-pressing ring; 330-metal sealing ring; 340-rubber sealing ring; 1-production casing. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the present invention, a casing head for an oil and gas wellhead proposed by the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0027] The above and other technical contents, features and effects of the utility model are clearly presented in the following detailed description of the specific implementation mode in conjunction with the accompanying drawings. Through the description of the specific implementation mode, the technical means and effects adopted by the utility model to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes, and are not used to limit the technical solutions of the utility model.

[0028] Embodiment 1 The casing head used in the oil wellhead is similar to the casing head used in the gas wellhead (in actual working conditions, the casing head used in the oil wellhead is often simpler, but the two should have the same or similar structure). It will not be described here in detail, so only the casing head of the gas wellhead is taken as an example. Figure 1 , Figure 1 The utility model is a structural schematic diagram of a casing head for a gas production wellhead provided in an embodiment of the utility model.

[0029] like Figure 1 As shown, the gas wellhead casing head of the utility model comprises: a casing head body 100, a mandrel-type casing hanger 200 and a metal sealing assembly 300; the casing head body 100 is coaxially sleeved outside the mandrel-type casing hanger 200, and the tubing head is arranged on the casing head body 100; the mandrel-type casing hanger 200 comprises: a first connecting part 210, a second connecting part 220 and a third connecting part 230 which are sequentially connected and interconnected.

[0030] In this embodiment, the first connection part 210, that is, the extension neck extending from the upper end of the mandrel-type casing hanger 200, extends out of the casing head body 100 and is connected to the tubing head; the second connection part 220 is arranged in the casing head body 100, and the second connection part 220 is sealed and connected to the casing head body 100 through the metal sealing assembly 300; the third connection part 230 is threadedly connected to the production casing 1; wherein, the outer diameter of the first connection part 210 is greater than or equal to the outer diameter of the production casing 1 connected to the third connection part 230.

[0031] In an optional embodiment, the interiors of the first connection part 210, the second connection part 220 and the third connection part 230 are interconnected through a through hole, and the diameter of the through hole is greater than or equal to the inner diameter of the production casing 1, so as to facilitate the passage of downhole working tools. Further, in order to maintain the connection performance between the through hole set in the mandrel type casing hanger 200 and the production casing 1, the diameter of the through hole can be only slightly larger than the inner diameter of the production casing 1. For example, if the specification of the production casing 1 is 5 1 / 2"×9.17, and its theoretical inner diameter is 121.36, then the diameter of the through hole of the hanger 200 can be 121.5 +0.8 or 122 +0.8 .

[0032] In an optional embodiment, a connecting internal thread is provided in the third connecting portion 230 for connecting to the production casing 1 , and the connecting internal thread matches with the thread of the production casing 1 .

[0033] Preferably, the connecting internal thread is an oblong thread or a stepped thread, which has good connection strength performance and certain sealing performance.

[0034] In an optional embodiment, a pick-up and lifting thread 240 is provided between the first connection portion 210 and the second connection portion 220 , and the pick-up and lifting thread 240 can be connected to the internal thread of the pick-up and lifting tool to achieve the pick-up and delivery of the assembly for installing the mandrel-type casing hanger 200 .

[0035] It is worth noting that by reducing the size of the production casing 1, the volume of the annulus between the oil pipe and the casing becomes smaller, so that it is easier to reach the formation fracturing pressure during the fracturing process, that is, the pressure is easy to increase. By reasonably setting the connection size of the first connection part 210 and the third connection part 230, the outer diameter of the first connection part 210 matches the inner diameter of the connection hole of the tubing head, and the internal thread of the third connection part 230 matches the thread of the production casing 1, ensuring the use of a casing with a smaller diameter, and can also be connected without replacing the original matching tubing head. It is easy to use, greatly reduces the operating cost, reduces the variety of tubing heads, and facilitates production and warehouse management.

[0036] In an optional embodiment, an inverted cava hanger can also be provided in the casing head of the oil and gas production wellhead of the utility model; the casing head body 100 is coaxially sleeved outside the inverted cava hanger, and the inverted cava hanger is located below the mandrel-type casing hanger 200, and is used to connect the surface casing, and the production casing 1 suspended by the mandrel-type casing hanger 200 is located in the surface casing.

[0037] It is worth noting that one of the main functions of the casing head is to suspend and reliably connect the casing, and this function is usually achieved through a casing hanger. In this embodiment, a mandrel-type casing hanger 200 is used, and the mandrel-type casing hanger 200 is widely used in actual production due to its reliability. Specifically, the mandrel-type casing hanger 200 is suspended by forming a threaded connection with the casing. When suspended, the casing and the mandrel-type casing hanger 200 have a coaxial central axis. In actual use, the production casing 1 is threadedly connected to the third connection portion 230 of the mandrel-type casing hanger 200, and the first connection portion 210 of the mandrel-type casing hanger 200 extends out and connects the tubing head. Due to production habits, the connection size of the upper end of the mandrel-type casing hanger 200 is often the same as the connection size of the outer diameter of the production casing 1, that is, if the first connection part 210 matches a connection structure of a certain size (equivalent to the inner diameter size of the connection hole in the lower flange of the tubing spool of the tubing head), the connection size of the inner thread of the third connection part 230 should also be the same size as the outer diameter of the production casing 1, that is, if a large-sized production casing 1 is used, a large-sized mandrel-type casing hanger 200 and tubing head should be used, and if a small-sized production casing 1 is used, a small-sized mandrel-type casing hanger 200 and tubing head should be used. In some cases, the production casing 1 is also connected to the mandrel-type casing hanger 200 through a casing double male nipple, but these connection threads should also match each other.

[0038] Correspondingly, as long as the inner hole size of the first connection part 210, the second connection part 220 and the third connection part 230 is maintained, that is, the inner hole size of the mandrel-type casing hanger 200 is maintained slightly larger than or the same as the inner hole size of the production casing 1, by increasing the outer diameter size of the first connection part 210, and at the same time making the inner thread of the third connection part 230 with a large outer diameter connection size specification, follow the connection size specification of the production casing 1 to make corresponding adjustments and maintain the same size, there is no need to prepare two sets of tubing heads with connection holes of the size specification corresponding to the production casing 1, that is, the tubing head of the larger size specification is universally adapted. In other words, the first connection part 210 is connected to the inner diameter of the connection hole of the tubing head of the larger size specification and sealed, and the third connection part 230 is threadedly connected to the production casing 1 of the smaller size specification, thereby realizing the connection between the tubing head of the larger size specification and the production casing 1 of the smaller size specification.

[0039] In addition, when the outer diameter of the production casing 1 is a small size, if the outer diameter of the first connection part 210 is the same as the outer diameter of the production casing 1, it is equivalent to limiting the outer diameter of the first connection part 210, resulting in insufficient wall thickness of the first connection part 210, and it is difficult to ensure its internal pressure resistance. Therefore, by increasing the outer diameter of the first connection part 210, its wall thickness can also be increased, thereby enhancing the internal pressure resistance of the casing head and meeting the requirements of the production fracturing process.

[0040] See also Figure 2 , Figure 2 It is a partial enlarged view A of a casing head of a gas production wellhead provided by an embodiment of the utility model.

[0041] like Figure 2 As shown, the metal sealing assembly 300 of the utility model adopts a combined seal of metal and rubber, including: a top screw 310, a pressure ring 320 and a metal sealing ring 330; the central axis of the top screw 310 is perpendicular to the central axis of the mandrel type casing hanger 200; the top screw 310 is threadedly connected to the casing head body 100; a pressure ring 320 is arranged between one end of the top screw 310 and the mandrel type casing hanger 200; and the metal sealing ring 330 is arranged below the pressure ring 320.

[0042] Specifically, the top screw 310 is screwed in along a direction perpendicular to the central axis of the core shaft casing hanger 200. The front end of the top screw 310 is provided with a taper, and the front end squeezes the upper part of the pressing ring 320, thereby pushing the pressing ring 320 to move downward. The metal sealing ring 330 includes an outer ring and an inner ring. The pressing ring 320 moves downward to squeeze the top of the outer ring, and the outer ring moves downward accordingly and squeezes the inner ring. Under the action of the inclined surface between the inner and outer rings, the outer ring expands outward and the inner ring expands inward, thereby achieving reliable sealing.

[0043] In an optional embodiment, the metal sealing assembly 300 also includes: at least two rubber sealing rings 340; at least two rubber sealing rings 340 are arranged below the metal sealing ring 330, and are sequentially and spaced apart on the mandrel type casing hanger 200, and the two rubber sealing rings 340 act synchronously to improve the sealing reliability between the mandrel type casing hanger 200 and the casing head body 100.

[0044] The casing head for oil and gas production wellhead provided by the embodiment of the utility model realizes a sealed connection with the tubing head by thickening the extension neck extending from the upper end of the mandrel-type casing hanger, that is, by thickening the first connection part extending from the casing head body; the mandrel-type casing hanger is arranged in the casing head body, and realizes a sealed connection with the casing head body through a metal sealing assembly in which metal and rubber work together, and the third connection part of the mandrel-type casing hanger is provided with an internal thread for connecting the production casing. Since the casing hanger is independently designed and manufactured, the dimensions of its two ends can be customized according to the actual connection dimensions of the casing and the connected tubing head, and the outer diameter dimension of the first connection part located at the top is larger than the connection dimension of the production casing connected to the third connection part located at the bottom, so that it can adapt to production casings of different sizes, realize a sealed connection with the tubing head, and reduce the variety cost of spare parts and the workload of disassembly and assembly. At the same time, by increasing the outer diameter of the first connection part, its wall thickness is also increased, thereby enhancing the internal pressure resistance of the upper extension neck of the mandrel-type casing head.

[0045] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant is intended to cover non-exclusive inclusion, so that the article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or device including the elements. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The orientation or position relationship indicated by "up", "down", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the utility model.

[0046] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be 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 casing head for oil and gas production wellhead, characterized in that: include: A casing head body (100), a mandrel-type casing hanger (200) and a metal sealing assembly (300); The casing head body (100) is coaxially sleeved outside the mandrel-type casing hanger (200); The mandrel-type casing hanger (200) comprises: a first connection part (210), a second connection part (220) and a third connection part (230) which are sequentially connected and communicated with each other; The first connecting portion (210) extends out of the casing head body (100) and is connected to the tubing head; The second connection portion (220) is disposed in the casing head body (100), and the second connection portion (220) is sealedly connected to the casing head body (100) via the metal sealing assembly (300); The third connection portion (230) is threadedly connected to the production casing (1); The outer diameter of the first connecting portion (210) is greater than or equal to the outer diameter of the production casing (1) connected to the third connecting portion (230); The metal sealing assembly (300) adopts a combined seal of metal and rubber.

2. The casing head for oil and gas production wellhead according to claim 1, characterized in that: The interiors of the first connecting portion (210), the second connecting portion (220) and the third connecting portion (230) are interconnected via a through hole, and the diameter of the through hole is greater than or equal to the inner diameter of the production casing (1).

3. The casing head for oil and gas production wellhead according to claim 1, characterized in that: The third connecting portion (230) is provided with a connecting internal thread, and the connecting internal thread matches the thread of the production casing (1).

4. The casing head for oil and gas production wellhead according to claim 1, characterized in that: A pick-up and lifting thread (240) is provided between the first connecting portion (210) and the second connecting portion (220).

5. The casing head for oil and gas production wellhead according to claim 1, characterized in that: The metal sealing assembly (300) comprises: a top screw (310), a pressure ring (320) and a metal sealing ring (330); The central axis of the top screw (310) is perpendicular to the central axis of the mandrel-type casing hanger (200); the top screw (310) is threadedly connected to the casing head body (100); a pressing ring (320) is provided between one end of the top screw (310) and the mandrel-type casing hanger (200); The metal sealing ring (330) is arranged below the pressing ring (320).

6. The casing head for oil and gas production wellhead according to claim 5, characterized in that: The metal sealing assembly (300) further comprises: at least two rubber sealing rings (340); The at least two rubber sealing rings (340) are arranged below the metal sealing ring (330) and are sequentially sleeved on the mandrel-type casing hanger (200) at intervals.

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