Anti-blocking casing head for deep coal bed gas horizontal well

Abstract

The utility model relates to an anti-blocking casing head for a deep coal bed gas horizontal well, which belongs to the field of oil and gas production wellhead devices and comprises a casing head body, a mandrel type casing hanger and a sealing component. The casing head body is coaxially arranged outside the mandrel type casing hanger in a sleeved mode, and the mandrel type casing hanger is connected with the casing head body in a sealed mode through the sealing assembly. The mandrel type casing hanger is in threaded connection with the production casing, and the inner drift diameter d2 of the mandrel type casing hanger is larger than or equal to the inner drift diameter d1 of the production casing 1; the casing head body is provided with a plurality of discharge ports, and the plurality of discharge ports are all located below the mandrel type casing hanger; the range of the inner diameter d of at least one discharge port is 2d3 < = d < = d1; wherein d is the inner diameter of the discharge port; d1 is the inner drift diameter of the production sleeve; d3 is the radial clearance of the outer annulus of the production casing. According to the utility model, the drift diameter of the discharge port of the casing head is reasonably set, so that the feasibility of replacing a slip type hanger with a mandrel type casing hanger is improved.

Description

Technical Field

[0001] The utility model belongs to the field of oil and gas production wellhead devices, and in particular relates to an anti-blocking casing head used for a deep coalbed methane horizontal well. Background Art

[0002] With the development of coalbed methane, the drilling depth has also increased. The mining depth of deep coalbed methane is usually between 2500 and 4000 meters. At present, multi-layer well construction technology is often used to divide the drilling process into several stages for construction, such as Figure 1 As shown in the figure, the wellbore structure of the deep coalbed methane horizontal well is the surface casing, technical casing and production casing from the outside to the inside. Due to the deep mining depth, the formation pressure also increases. When mining enters the horizontal drilling coal seam well, the coal blocks and coal gangue in the coal seam wellbore wall become very easy to fall off. Generally, well washing operations are required before the production casing is lowered. The coal blocks and coal gangue in the coal seam wellbore wall are more likely to fall off after being soaked in the well washing fluid, and then carried out by the well washing fluid. Similarly, during the mud injection circulation operation before cement cementing, the coal blocks and coal gangue will also be carried out by the circulating mud. The production casing is suspended using a slip-type casing hanger. Since the slip hanger is installed in the waiting stage after the cementing is completed, the port of the production casing on the ground drilling platform is open before that, so that the coal blocks and coal gangue can be directly brought out, which is conducive to the discharge of the well washing fluid or mud.

[0003] However, the slips of the slip hanger are prone to deformation due to various reasons. After the slips are deformed, the slip hanger can no longer safely and reliably hang the production casing, resulting in false suspension. During the fracturing process, the pressure in the well increases, and the upward thrust causes the false suspension slip teeth to fail to bite, and in severe cases, the slip teeth may even fly out of the slip hanger assembly, resulting in serious equipment accidents or even personal accidents.

[0004] The mandrel-type casing hanger is suspended by threading the production casing. Compared with the use of slip-type hanging casing, it has higher reliability, but the mandrel-type casing hanger needs to be lowered together with the production casing and form a reliable seal with the casing head body. This makes the open port of the casing head on the ground drilling platform closed in advance, and the well washing fluid or mud carrying coal blocks and coal gangue is difficult to discharge smoothly. Therefore, a blocking-proof casing head for deep coalbed methane horizontal wells is needed. Utility Model Content

[0005] In order to solve the above problems existing in the prior art, the utility model provides an anti-blocking casing head for deep coalbed methane horizontal wells. The technical problem to be solved by the utility model is achieved through the following technical solutions:

[0006] The utility model provides an anti-blocking casing head for deep coalbed methane horizontal wells, comprising: a casing head body, a mandrel-type casing hanger and a sealing assembly; the casing head body is coaxially sleeved outside the mandrel-type casing hanger, and the mandrel-type casing hanger is sealed and connected to the casing head body through the sealing assembly; the mandrel-type casing hanger is threadedly connected to the production casing, and the inner diameter d2 of the mandrel-type casing hanger is greater than or equal to the inner diameter d1 of the production casing to prevent interference when the production tool is lowered; the casing head body is provided with a plurality of discharge ports, and the plurality of discharge ports are all located below the mandrel-type casing hanger; the range of the inner diameter d of at least one discharge port is:

[0007] 2d3≤d≤d1;

[0008] Wherein, d is the inner diameter of the discharge port 110; d1 is the inner diameter of the production casing 1; and d3 is the radial clearance of the outer annulus of the production casing 1.

[0009] In one embodiment of the utility model, at least one discharge port is connected to a flat valve, and the flat valve is connected to a pressure gauge or a stop valve.

[0010] In one embodiment of the present invention, the mandrel-type casing hanger comprises: a first connection part, a second connection part and a third connection part which are sequentially connected and interconnected; the first connection part extends out of the casing head body, the second connection part is sealed and connected to the casing head body through a sealing assembly, and the third connection part is threadedly connected to the production casing.

[0011] In one embodiment of the present invention, the outer diameter of the first connecting portion is greater than or equal to the outer diameter of the production casing.

[0012] In one embodiment of the present invention, a lifting thread is provided between the first connection portion and the second connection portion.

[0013] In one embodiment of the utility model, the sealing assembly is a metal seal, including: a top screw assembly, a pressure ring and a metal sealing ring; the top screw assembly is threadedly connected to the casing head body, and a pressure ring is arranged between one end of the top screw assembly and the core shaft casing hanger; the metal sealing ring is arranged below the pressure ring.

[0014] In one embodiment of the utility model, the sealing assembly further includes: two rubber sealing rings; the two rubber sealing rings are both arranged below the metal sealing ring and are sequentially sleeved on the mandrel-type casing hanger at intervals.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] The utility model of the anti-blocking casing head for deep coalbed methane horizontal wells adopts a mandrel-type casing hanger to hang the production casing, which has better hanging reliability. By reasonably setting the diameter size of the discharge port of the casing head, the well washing fluid or mud carrying coal blocks and coal gangue can be discharged smoothly from the discharge port, thereby improving the feasibility of using the mandrel-type casing hanger to replace the slip-type hanger.

[0017] 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

[0018] Figure 1 This is a schematic diagram of the wellbore structure of deep coalbed methane;

[0019] Figure 2 It is a structural schematic diagram of an anti-blocking casing head for deep coalbed methane horizontal wells provided by an embodiment of the utility model;

[0020] Figure 3 It is a structural schematic diagram of a mandrel-type casing hanger provided by an embodiment of the utility model;

[0021] Figure 4 It is a structural schematic diagram of a sealing assembly provided by an embodiment of the utility model;

[0022] Figure 5 It is a schematic structural diagram of the outer annulus of the production casing 1 according to an embodiment of the utility model.

[0023] Figure markings: 100-casing head body; 110-discharge outlet; 120-flat valve; 200-core type casing hanger; 210-first connection part; 220-second connection part; 230-third connection part; 240-lifting thread; 300-sealing assembly; 310-top screw assembly; 320-pressing ring; 330-metal sealing ring; 340-rubber sealing ring; 1-production casing; 2-technical casing; 3-surface casing. DETAILED DESCRIPTION

[0024] In order to further explain the technical means and effects adopted by the utility model to achieve the predetermined utility model purpose, the following is a detailed description of an anti-blocking casing head for deep coalbed methane horizontal wells proposed according to the utility model in combination with the accompanying drawings and specific implementation methods.

[0025] 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, and are not used to limit the technical solution of the utility model.

[0026] Embodiment 1

[0027] like Figure 2 As shown, this embodiment provides an anti-blocking casing head for deep coalbed methane horizontal wells, including: a casing head body 100, a mandrel casing hanger 200 and a sealing assembly 300; the casing head body 100 is coaxially sleeved outside the mandrel casing hanger 200, and the mandrel casing hanger 200 is sealed and connected to the casing head body 100 through the sealing assembly 300; the mandrel casing hanger 200 is threadedly connected to the production casing 1, and the inner diameter d2 of the mandrel casing hanger 200 is greater than or equal to the inner diameter d1 of the production casing 1 to prevent interference when the production tool is lowered; a plurality of discharge ports 110 are arranged on the casing head body 100, and the plurality of discharge ports 110 are all located below the mandrel casing hanger 200.

[0028] The principle is that, if a slip-type hanger is used, during the well-washing stage, the port of the production casing 1 on the ground drilling platform is open, so that the coal blocks and coal gangue can be directly carried out by the well-washing fluid or mud through the annular gap between the technical casing 2 and the production casing 1. When the mandrel-type casing hanger 200 is used, the well-washing fluid or mud carrying coal blocks and coal gangue is difficult to discharge because the open port of the casing head on the ground drilling platform is closed in advance. On this basis, by reasonably improving the discharge port 110, the well-washing fluid or mud carrying coal blocks and coal gangue can be smoothly discharged from the discharge port 110 of the casing head.

[0029] Specifically, the range of the inner diameter d of at least one discharge port is:

[0030] 2d3≤d≤d1; (1)

[0031] Among them, d is the inner diameter of the discharge port 110; d1 is the inner diameter of the production casing 1; and d3 is the radial clearance of the outer annulus of the production casing 1, that is, the maximum radial clearance of the annulus between the production casing 1 and the technical casing 2.

[0032] By improving the discharge port 110 , it is possible to ensure that the discharge port 110 is not blocked by coal blocks and coal gangue, thereby ensuring that the well washing fluid or mud is discharged smoothly.

[0033] For example, Figure 4As shown, taking a commonly used technical casing 2 as an example, its outer diameter is 9 5 / 8", i.e. 244.5mm, and its wall thickness is 11mm, then the inner diameter is 226.5mm, and the outer diameter of the production casing is 51 / 2", i.e. 139.7mm, and its wall thickness is 12.7mm. It is not difficult to deduce that the radial clearance of the annulus between the technical casing 2 and the production casing 1 is 43.4mm, that is, the radial clearance d3 of the outer annulus of the production casing 1 is 43.4mm.

[0034] In the actual construction process, the coal blocks and coal gangue that fall off the coal seam follow the flow of the well washing fluid before casing lowering or the thin cement slurry used for well washing before cementing, and roll, rub and collide with each other, making the sharp edges and angles when falling off gradually become smooth, and the shape gradually transforms into multi-faceted spheres and multi-faceted ellipsoids. Among them, the proportion of multi-faceted spheres is more than 85%, and its diameter is usually smaller than the radial clearance of the annulus (43.4mm); a very small number of them are multi-faceted ellipsoids, and their maximum major axis is about 2 times the minor axis, and the maximum major axis is between 30 and 65mm, which is caused by Figure 5 As shown, it is not difficult to deduce that the major axis size d4 of the largest ellipse that can be accommodated in the annular space between the technical casing 2 and the production casing 1 is more than twice its minor axis, and the minor axis is the radial gap d3 of the outer annulus of the production casing 1, which allows a single coal block and coal gangue to be discharged through the annular space between the technical casing 2 and the production casing 1, but the discharge port 110 needs to accommodate the coal blocks and coal gangue discharged from the entire annulus, and in practice there will be multiple coal blocks and coal gangue of different sizes discharged from the discharge port 110 at the same time, so the inner diameter of the discharge port 110 needs to be at least twice the radial gap of the annulus.

[0035] For example, taking the production casing 1 with an outer diameter of 5 1 / 2 inches as an example, its wall thickness is usually 12.7 mm, and its inner diameter is 114.3 mm. The inner diameter of the discharge port 110 provided on the casing head body 100 should be at least twice the radial clearance of the annulus, that is, 86.8 mm. Usually, it is rounded up, so it can be 90 mm. According to the shape and size of the coal blocks and coal gangue returned to the ground sedimentation tank obtained from the deep coalbed methane mining for many years, the inner diameter of the discharge port 110 should not exceed 100 mm. The inner diameter of 114.3mm is feasible. In the existing series of conventional casing head standards for natural gas extraction, the diameter size of the discharge port 110 ranges from 52 to 65mm, which cannot ensure the smooth discharge of coal blocks and coal gangue in deep coalbed methane horizontal wells. Taking into account the permissibility of production and manufacturing and the nominal size series in the recommended standard "Petroleum and Natural Gas Drilling Equipment Wellhead Equipment and Oil Tree Equipment GB / T22513-2023", the inner diameter size of the discharge port 110 can be set to 4 1 / 16", that is, 103mm.

[0036] In an optional embodiment, at least one discharge port 110 is connected to a flat valve 120, and the flat valve 120 is connected to a pressure gauge or a stop valve, wherein the pressure gauge is used to detect the passage pressure of the passage where the flat valve 120 is located, and the stop valve can protect the pressure gauge or the passage where it is located to avoid accidental damage caused by excessive pressure, and the pressure gauge can also be replaced by closing the stop valve.

[0037] Optionally, the connection between the discharge port 110 and the flat valve 120 is a flange connection.

[0038] like Figure 2 and Figure 3 As shown, in an optional embodiment, the mandrel-type casing hanger 200 includes: 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 connection part 210 extends out of the casing head body 100, the second connection part 220 is sealed and connected to the casing head body 100 through a sealing assembly 300, and the third connection part 230 is threadedly connected to the production casing 1. The interiors of the first connection part 210, the second connection part 220 and the third connection part 230 are communicated with each other through through holes.

[0039] Optionally, the outer diameter of the first connecting portion 210 is greater than or equal to the outer diameter of the production casing 1 .

[0040] Furthermore, 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 with the thread of a pick-up and lifting tool to realize the overall pick-up and delivery of the mandrel-type casing hanger 200 .

[0041] like Figure 2 and Figure 4 As shown, in an optional embodiment, the sealing assembly 300 is a metal seal, including: a top screw assembly 310, a pressure ring 320 and a metal sealing ring 330; the top screw assembly 310 is threadedly connected to the casing head body 100, and a pressure ring 320 is arranged between one end of the top screw assembly 310 and the core shaft casing hanger 200; the metal sealing ring 330 is arranged below the pressure ring 320.

[0042] Furthermore, the sealing assembly 300 further includes: two rubber sealing rings 340 ; the two rubber sealing rings 340 are both disposed below the metal sealing ring 330 , and are sequentially sleeved on the mandrel-type casing hanger 200 at intervals.

[0043] The principle is as follows: the end face of the top screw assembly 310 is a conical surface and cooperates with the pressing ring 320 through the conical surface. The pressing ring 320 moves downward, transmits pressure and presses the outer ring of the metal sealing ring 330, so that the outer ring and the inner ring of the metal sealing ring 330 are pressed and squeezed to squeeze the gap between the mandrel type casing hanger 200 and the casing head body 100, thereby achieving a reliable seal between the mandrel type casing hanger 200 and the casing head body 100.

[0044] Taking the third well as an example, the second layer of casing head has been installed and the drilling process has been completed. The working principle of the anti-blocking casing head for deep coalbed methane horizontal wells in this embodiment is that the mandrel casing hanger 200 is connected to the production casing 1 through a thread. Since the upper end of the production casing 1 is connected to the mandrel casing hanger 200 at this time and forms a seal with the casing head body 100 through the sealing assembly 300, the upper end of the annulus between the production casing 1 and the casing head body 100 is closed. Therefore, the well washing fluid or mud carrying coal blocks and coal gangue is returned from the annulus between the technical casing 2 and the production casing 1 through the discharge port 110 and the valve 120 of the casing head body 100 and finally enters the sedimentation tank through the pipeline.

[0045] The utility model of the anti-blocking casing head for deep coalbed methane horizontal wells adopts a mandrel-type casing hanger to hang the production casing, which has better hanging reliability. By reasonably setting the diameter size of the discharge port of the casing head, the well washing fluid or mud carrying coal blocks and coal gangue can be discharged smoothly from the discharge port, thereby improving the feasibility of using the mandrel-type casing hanger to replace the slip-type hanger.

[0046] 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.

[0047] 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 plugging prevention casing head for deep coalbed methane horizontal wells, characterized in that: include: A casing head body (100), a mandrel-type casing hanger (200) and a sealing assembly (300); The casing head body (100) is coaxially sleeved outside the mandrel-type casing hanger (200), and the mandrel-type casing hanger (200) is sealedly connected to the casing head body (100) via the sealing assembly (300); The mandrel-type casing hanger (200) is threadedly connected to the production casing (1), and the inner diameter d2 of the mandrel-type casing hanger (200) is greater than or equal to the inner diameter d1 of the production casing (1); The casing head body (100) is provided with a plurality of discharge ports (110), and the plurality of discharge ports (110) are all located below the mandrel-type casing hanger (200); the range of the inner diameter d of at least one of the discharge ports (110) is: 2d3≤d≤d1; Wherein, d is the inner diameter of the discharge port (110); d1 is the inner diameter of the production casing (1); and d3 is the radial clearance of the outer annulus of the production casing (1).

2. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 1, characterized in that: At least one of the discharge ports (110) is connected to a flat valve (120), and the flat valve (120) is connected to a pressure gauge or a stop valve.

3. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 1, characterized in that: 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 connected in sequence and communicate with each other; the first connection part (210) extends out of the casing head body (100), the second connection part (220) is sealedly connected to the casing head body (100) through the sealing assembly (300), and the third connection part (230) is threadedly connected to the production casing (1).

4. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 3, characterized in that: The outer diameter of the first connecting portion (210) is greater than or equal to the outer diameter of the production casing (1).

5. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 3, characterized in that: A pick-up and lifting thread (240) is provided between the first connecting portion (210) and the second connecting portion (220).

6. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 1, characterized in that: The sealing assembly (300) is a metal seal, comprising: a top screw assembly (310), a pressure ring (320) and a metal sealing ring (330); the top screw assembly (310) is threadedly connected to the casing head body (100), and a pressure ring (320) is arranged between one end of the top screw assembly (310) and the mandrel-type casing hanger (200); the metal sealing ring (330) is arranged below the pressure ring (320).

7. The anti-blocking casing head for deep coalbed methane horizontal well according to claim 6, characterized in that: The sealing assembly (300) further comprises: two rubber sealing rings (340); the two rubber sealing rings (340) are both arranged below the metal sealing ring (330) and are sequentially sleeved on the mandrel-type casing hanger (200) at intervals.

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