Coalbed methane horizontal well cementing device and method

Abstract

The present invention provides a coalbed methane horizontal well cementing device and method. The coalbed methane horizontal well cementing device includes: a technical casing, which is located in the vertical section of the horizontal well; a production casing, which is a plastic casing and is located in the horizontal section of the horizontal well; a casing joint, the ends of which are respectively connected to the technical casing and the production casing; and a packer, which is provided at the end where the technical casing is connected to the casing joint, and the casing joint and the packer are both located in the deflection section of the horizontal well. The present invention solves the problem in the prior art that the horizontal section of a coalbed methane horizontal well cannot only seal the aquifer above the gas-producing coal seam.

Description

Technical Field

[0001] The present invention relates to the technical field of coal drilling and development, and in particular to a coalbed methane horizontal well cementing device and method. Background Art

[0002] Surface horizontal directional drilling technology has become an important way to achieve comprehensive benefits in the development and utilization of coalbed methane in coalfields. For soft and loose coal reservoirs, a horizontal through-hole construction process is usually adopted. The method of using horizontal wells to produce gas and vertical wells to extract gas is beneficial for pre-extraction of gas from soft and loose coal. Since the casing used in conventional well construction is all steel pipe, running long steel pipes (screen pipes) into horizontal wells for pre-extraction of gas will make it impossible for the coal mining machine to cut the steel pipes during coal mining. At the same time, during well construction, the strata above the coal seam contain a lot of water, which affects gas production. Therefore, the aquifer above the coal seam must be sealed. Conventional cementing methods cannot achieve this technical requirement, which will greatly affect coal mining efficiency and may even make coal mining impossible.

[0003] As can be seen from the above, the existing technology has the problem that the horizontal section of the coalbed methane horizontal well cannot only seal the aquifer above the gas-producing coal seam. Summary of the Invention

[0004] The main purpose of the present invention is to provide a coalbed methane horizontal well cementing device and method to solve the problem in the prior art that the horizontal section of the coalbed methane horizontal well cannot only seal the aquifer above the gas-producing coal seam.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a coalbed methane horizontal well cementing device is provided, comprising: a technical casing, which is located in the vertical section of the horizontal well; a production casing, which is a plastic casing and is located in the horizontal section of the horizontal well; a casing joint, wherein the two ends of the casing joint are respectively connected to the technical casing and the production casing; and a packer, which is arranged at one end where the technical casing is connected to the casing joint, and the casing joint and the packer are both located in the deflection section of the horizontal well.

[0006] Furthermore, the sealer includes: a sealing bag, which is sleeved on the outer surface of the technical casing and connected to the inner cavity of the technical casing, and the cement slurry enters the sealing bag and expands the sealing bag to seal the annulus between the technical casing and the well wall of the horizontal well; a grouting pipe, one end of the grouting pipe extends into the sealing bag, and the two ends of the grouting pipe respectively have a first opening and a second opening, the first opening is located in the sealing bag, and the second opening is located in the annulus between the technical casing and the well wall of the horizontal well, and the second opening is away from the casing joint relative to the sealing bag; a ball seat, the ball seat is fixedly arranged in the inner cavity of the technical casing, the ball seat has a central through hole, and the ball seat is close to the casing joint relative to the sealing bag; a steel ball, the steel ball is used to seal the central through hole.

[0007] Furthermore, the packer also includes a bursting valve, which is arranged at the second opening and has a preset bursting pressure. When the cement slurry fills the packing bag and the pressure is greater than the preset bursting pressure, it enters the annulus between the technical casing and the well wall of the horizontal well from the second opening.

[0008] Furthermore, the packer also includes a first one-way valve, which is arranged on the grouting pipe and is used to grout into the packer bag and prevent the cement slurry in the packer bag from flowing into the annulus between the technical casing and the well wall of the horizontal well.

[0009] Further, a first one-way valve is provided at the first opening.

[0010] Furthermore, the isolation device also includes a second one-way valve. A through hole is opened in the wall of the technical casing, and the isolation bag is connected to the inner cavity of the technical casing through the through hole. The second one-way valve is arranged at the through hole to prevent the cement slurry in the annulus between the technical casing and the wall of the horizontal well from flowing back into the inner cavity of the technical casing.

[0011] Furthermore, the second one-way valve is connected to the grouting pipe, and the connection point between the second one-way valve and the grouting pipe is located between the first opening and the second opening.

[0012] Furthermore, there are multiple grouting pipes, which are spaced apart along the circumference of the technical casing.

[0013] Furthermore, the packer also includes two guide blocks, which are sleeved on the outer surface of the technical casing and are respectively located on both sides of the packing bag.

[0014] Furthermore, the distance between the outer wall of the guide block and the outer surface of the technical sleeve is greater than the distance between the outer wall of the sealing bag and the outer surface of the technical sleeve; and / or the distance between the outer wall of the guide block and the outer surface of the technical sleeve is greater than the distance between the grouting pipe and the outer surface of the technical sleeve.

[0015] Furthermore, the production casing is a PE casing.

[0016] According to another aspect of the present invention, a method for cementing a coalbed methane horizontal well is provided, and the above-mentioned coalbed methane horizontal well cementing device is used to implement the cementing method, and the cementing method includes: lowering the coalbed methane horizontal well cementing device into the horizontal well; performing a well washing operation, and then performing a ball throwing operation to seal the ball seat of the packer; pumping cement slurry from the inner cavity of the technical casing into the packer bag, so that the packer bag expands and seals the annulus between the technical casing and the well wall of the horizontal well; when the cement slurry fills the packer bag, adjusting the pressure of the cement slurry to be greater than the preset blasting pressure of the bursting valve of the packer, so that the cement slurry enters the annulus between the technical casing and the well wall of the horizontal well and flows out of the ground, completing grouting; completely replacing the cement slurry in the inner cavity of the technical casing with clean water of the same volume, closing the technical casing and holding the pressure for a preset time, and completing cementing.

[0017] The technical solution of the present invention connects the technical casing and the production casing by providing a casing joint, and a packer is provided at the end where the technical casing connects to the casing joint. This not only seals the aquifer above the production layer but also protects the production layer, thereby achieving rapid, safe, and efficient extraction of coalbed methane. This solves the problem in the prior art that the horizontal section of a coalbed methane horizontal well cannot only seal the aquifer above the gas-producing coal seam. In addition, the use of plastic casing as the production casing can prevent the coal shearer from being unable to cut through the production casing during coal mining, thereby achieving both gas extraction and effectively eliminating the impact of the coal shearer on the coal mining process, thereby ensuring coal mining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 A schematic structural diagram of a coalbed methane horizontal well cementing device in a specific embodiment of the present invention is shown; and

[0020] Figure 2 FIG1 shows a schematic structural diagram of an occluder in a specific embodiment of the present invention;

[0021] Figure 3 A schematic structural diagram of a casing joint in a specific embodiment of the present invention is shown;

[0022] Figure 4 A flow chart of a coalbed methane horizontal well cementing method in a specific embodiment of the present invention is shown.

[0023] The above drawings include the following reference numerals:

[0024] 10. Technical casing; 20. Production casing; 30. Casing joint; 31. First joint; 32. Second joint; 40. Packer; 41. Packer bag; 42. Grouting pipe; 421. First opening; 422. Second opening; 43. Ball seat; 44. Burst valve; 45. First one-way valve; 46. Second one-way valve; 47. Pilot block; 48. Steel ball; 1. Horizontal well. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0027] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity direction; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above directional words are not used to limit the present invention.

[0028] Obviously, the embodiments described above are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] In order to solve the problem in the prior art that the horizontal section of a coalbed methane horizontal well cannot only seal the aquifer above the gas-producing coal seam, the present invention provides a coalbed methane horizontal well cementing device and method.

[0030] like Figure 1 As shown, the coalbed methane horizontal well cementing apparatus includes a technical casing 10, a production casing 20, a casing joint 30, and a packer 40. The technical casing 10 is located in the vertical section of the horizontal well 1. The production casing 20 is a plastic casing and is located in the horizontal section of the horizontal well 1. The ends of the casing joint 30 are connected to the technical casing 10 and the production casing 20, respectively. The packer 40 is disposed at the end where the technical casing 10 connects to the casing joint 30. Both the casing joint 30 and the packer 40 are located in the deflection section of the horizontal well 1, i.e., at the coal seam roof.

[0031] By connecting the technical casing 10 and the production casing 20 with a casing joint 30 and installing a packer 40 at the end where the technical casing 10 connects to the casing joint 30, the aquifer above the production layer is sealed and protected, thereby achieving rapid, safe, and efficient extraction of coalbed methane. Furthermore, the use of plastic casing as the production casing 20 prevents the shearer from being unable to cut through the production casing 20 during coal mining, thereby enabling gas extraction and effectively eliminating the impact of the shearer on the coal mining process, thereby ensuring coal mining efficiency.

[0032] In this embodiment, the production casing 20 is a PE casing. PE material has the characteristics of low density, high strength, good toughness, and ease of cutting and welding. This ensures normal coal mining while preventing the coal mining machine from being unable to cut through the production casing 20, which could lead to reduced coal mining efficiency or even the inability to mine. Furthermore, the technical casing 10 is generally a steel pipe. By providing a casing joint 30 to connect the PE pipe and the steel pipe, this not only solves the problem of not being able to install a steel pipe in the horizontal section of the coal seam, but also addresses the technical difficulties of PE pipe installation, such as its high flexibility, light weight, high buoyancy, and susceptibility to deformation, bending, and breakage. Of course, the production casing 20 can also be made of other materials, and the selection can be based on actual needs.

[0033] like Figure 2 As shown, the packer 40 includes a packer bag 41, a grouting pipe 42, a ball seat 43 and a steel ball 48. The packer bag 41 is sleeved on the outer surface of the technical casing 10 and is connected to the inner cavity of the technical casing 10. Cement slurry enters the packer bag 41 and expands the packer bag 41 to isolate the annulus between the technical casing 10 and the well wall of the horizontal well 1. In this way, through the isolation of the packer bag 41, the cement slurry can only be used to seal and cement the well from above the packer bag 41. One end of the grouting pipe 42 extends into the packer bag 41, and the two ends of the grouting pipe 42 respectively have a first opening 421 and a second opening 422. The first opening 421 is located in the packer bag 41, and the second opening 422 is located in the annulus between the technical casing 10 and the well wall of the horizontal well 1, and the second opening 422 is away from the casing joint 30 relative to the packer bag 41. Cement slurry flows through a grouting pipe 42 from a barrier bag 41 into the annulus between the technical casing 10 above the barrier bag 41 and the wellbore of the horizontal well 1, thereby sealing the aquifer above the gas-producing coal seam. A ball seat 43 is fixedly mounted within the inner cavity of the technical casing 10. The ball seat 43 has a central through-hole and is positioned relative to the barrier bag 41, near the casing joint 30. When the ball is dropped, the steel ball 48 enters the technical casing 10 and fits snugly with the ball seat 43, sealing the central through-hole and preventing cement slurry from entering the production casing 20.

[0034] like Figure 2As shown, the packer 40 also includes a bursting valve 44. Bursting valve 44 is disposed at a second opening 422 and has a preset bursting pressure. Once the cement slurry fills the packer bag 41 and the pressure exceeds the preset bursting pressure, it enters the annulus between the technical casing 10 and the wellbore of the horizontal well 1 through the second opening 422. The provision of bursting valve 44 allows the cement slurry to enter the annulus between the technical casing 10 and the wellbore of the horizontal well 1 after filling the packer bag 41, minimizing air bubbles in the cement slurry and ensuring cementing quality.

[0035] In this embodiment, the preset bursting pressure is 3 MPa to 5 MPa.

[0036] like Figure 2 As shown, the packer 40 further includes a first one-way valve 45. The first one-way valve 45 is disposed on the grouting pipe 42 and is used to inject grout into the packer bag 41 and prevent the cement slurry in the packer bag 41 from flowing into the annulus between the technical casing 10 and the wellbore of the horizontal well 1. Specifically, the first one-way valve 45 is disposed at the first opening 421.

[0037] like Figure 2 As shown, the packer 40 also includes a second one-way valve 46. A through-hole is provided in the wall of the technical casing 10, through which the packer bag 41 communicates with the inner cavity of the technical casing 10. The second one-way valve 46 is disposed at the through-hole to prevent cement slurry in the annulus between the technical casing 10 and the wellbore wall of the horizontal well 1 from flowing back into the inner cavity of the technical casing 10. Specifically, the second one-way valve 46 communicates with the grouting pipe 42, and the connection between the second one-way valve 46 and the grouting pipe 42 is located between the first opening 421 and the second opening 422.

[0038] In this embodiment, there are multiple grouting pipes 42, which are spaced apart along the circumference of the technical casing 10. It is understood that there are also multiple first one-way valves 45 and second one-way valves 46, the number of which is the same as the number of grouting pipes 42. This arrangement can increase the grouting speed of the cement slurry, thereby shortening the cementing time and improving cementing efficiency.

[0039] like Figure 2 As shown, the packer 40 also includes two guide blocks 47, which are sleeved on the outer surface of the technical casing 10 and located on either side of the packer bag 41. The guide blocks 47 can guide the insertion of the technical casing 10. At the same time, the guide blocks 47 protect the packer 40 from damage during drilling, especially the packer bag 41 and the grouting pipe 42. Specifically, the guide block 47 is annular in shape and includes three arc segments spaced apart along the circumference of the technical casing 10. The arc of each arc segment is approximately 120°.

[0040] In this embodiment, the distance between the outer wall of the pilot block 47 and the outer surface of the technical cannula 10 is greater than the distance between the outer wall of the sealing bag 41 and the outer surface of the technical cannula 10. Accordingly, the distance between the outer wall of the pilot block 47 and the outer surface of the technical cannula 10 is also greater than the distance between the grouting pipe 42 and the outer surface of the technical cannula 10. With this arrangement, the pilot blocks 47 on both sides can provide sufficient protection for the sealing bag 41 and grouting pipe 42 in the middle.

[0041] like Figure 4 As shown, the present application also provides a coalbed methane horizontal well cementing method, which adopts the above-mentioned coalbed methane horizontal well cementing device to implement the cementing method, and the cementing method includes: lowering the coalbed methane horizontal well cementing device into the horizontal well 1; performing a well washing operation, and then performing a ball throwing operation to seal the ball seat 43 of the packer 40; pumping cement slurry from the inner cavity of the technical casing 10 into the sealing bag 41 of the packer 40, so that the sealing bag 41 expands and seals the annulus between the technical casing 10 and the well wall of the horizontal well 1; when the cement slurry fills the sealing bag 41, adjusting the pressure of the cement slurry to be greater than the preset blasting pressure of the bursting valve 44 of the packer 40, so that the cement slurry enters the annulus between the technical casing 10 and the well wall of the horizontal well 1 and flows out of the ground, completing grouting; completely replacing the cement slurry in the inner cavity of the technical casing 10 with the same volume of clean water, closing the technical casing 10 and holding the pressure for a preset time, and completing cementing.

[0042] The specific process of sealing using the coalbed methane horizontal well cementing device in this application is as follows:

[0043] The production casing 20, casing joint 30, packer 40, and technical casing 10 are sequentially lowered into the horizontal well 1. First, the pump is turned on to flush the well. Flushing fluid flows from the technical casing 10 through the ball seat 43 into the casing joint 30, and then into the production casing 20 to flush the well. After flushing and flushing, the pump is turned off, and a steel ball 48 is dropped into the technical casing 10. Then, the pump is turned on to cement the well. Because the steel ball 48 blocks the downward flow of cement slurry, the cement slurry is pumped through the through hole of the technical casing 10 into the second one-way valve 46 of the packer 40. Then, through the grouting pipe 42, it is injected from the first one-way valve 45 into the packer bag 41. When the packer bag 41 is filled with cement slurry and in close contact with the wall of the horizontal well 1, the pressure reaches the preset bursting pressure, and the bursting valve 44 is opened. The cement slurry finally flows out to the surface through the annulus between the technical casing 10 and the wall of the horizontal well 1. After the grouting is completed, the cement slurry in the technical casing 10 is completely replaced with clean water of the same volume, and the technical casing 10 is closed to hold the pressure, thereby completing the cementing.

[0044] It should be noted that Figure 1 The arrows in the figure indicate the flow direction of cement slurry.

[0045] From the above description, it can be seen that the above-mentioned embodiment of the present invention achieves the following technical effects: by providing a casing joint 30 to connect the technical casing 10 and the production casing 20, and by providing a packer 40 at the end where the technical casing 10 is connected to the casing joint 30, the aquifer above the production layer is sealed and protected, thereby achieving rapid, safe, and efficient extraction of coalbed methane. In addition, the use of plastic casing as the production casing 20 prevents the coal mining machine from being unable to cut through the production casing 20 during coal mining, thereby achieving both gas extraction and effectively eliminating the impact of the coal mining machine on the coal seam during mining, thereby ensuring coal mining efficiency.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, tasks, devices, components and / or combinations thereof.

[0047] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0048] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A coalbed methane horizontal well cementing device, characterized in that: include: A technical casing (10), the technical casing (10) being located in a vertical section of the horizontal well (1); A production casing (20), wherein the production casing (20) is a plastic casing, and the production casing (20) is located in the horizontal section of the horizontal well (1); A casing joint (30), wherein both ends of the casing joint (30) are respectively connected to the technical casing (10) and the production casing (20); A packer (40), the packer (40) being arranged at one end of the technical casing (10) connected to the casing joint (30), the casing joint (30) and the packer (40) both being located in the deflection section of the horizontal well (1); The packer (40) comprises: A sealing bag (41), the sealing bag (41) is sleeved on the outer surface of the technical casing (10) and communicated with the inner cavity of the technical casing (10), and cement slurry enters the sealing bag (41) and expands the sealing bag (41) to seal the annulus between the technical casing (10) and the wellbore wall of the horizontal well (1); a grouting pipe (42), one end of the grouting pipe (42) extending into the packing bag (41), and two ends of the grouting pipe (42) respectively having a first opening (421) and a second opening (422), the first opening (421) being located in the packing bag (41), the second opening (422) being located in the annulus between the technical casing (10) and the wellbore of the horizontal well (1), and the second opening (422) being away from the casing joint (30) relative to the packing bag (41); a ball seat (43), the ball seat (43) being fixedly disposed in the inner cavity of the technical sleeve (10), the ball seat (43) having a central through hole, and the ball seat (43) being close to the sleeve joint (30) relative to the sealing bag (41); a steel ball (48), the steel ball (48) being used to seal the central through hole; a bursting valve (44), the bursting valve (44) being arranged at the second opening (422) so that the cement slurry, after filling the packing bag (41), enters the annulus between the technical casing (10) and the wellbore of the horizontal well (1), thereby reducing air bubbles in the cement slurry; The packer (40) further includes a second one-way valve (46), a through-hole is provided in the wall of the technical casing (10), the packer bag (41) is communicated with the inner cavity of the technical casing (10) through the through-hole, and the second one-way valve (46) is arranged at the through-hole to prevent the cement slurry in the annulus between the technical casing (10) and the well wall of the horizontal well (1) from flowing back into the inner cavity of the technical casing (10); The second one-way valve (46) is in communication with the grouting pipe (42); The packer (40) further comprises a guide block (47), wherein the guide blocks (47) are two in number, and the two guide blocks (47) are sleeved on the outer surface of the technical casing (10) and are respectively located on both sides of the packing bag (41).

2. The coalbed methane horizontal well cementing device according to claim 1, characterized in that: The bursting valve (44) has a preset bursting pressure, and the cement slurry fills the isolation bag (41) and the pressure is greater than the preset bursting pressure, and then enters the annulus between the technical casing (10) and the well wall of the horizontal well (1) from the second opening (422).

3. The coalbed methane horizontal well cementing device according to claim 1, characterized in that: The packer (40) further comprises a first one-way valve (45), which is arranged on the grouting pipe (42) and is used for injecting grout into the packer bag (41) and preventing the cement slurry in the packer bag (41) from flowing into the annulus between the technical casing (10) and the well wall of the horizontal well (1).

4. The coalbed methane horizontal well cementing device according to claim 3, characterized in that: The first one-way valve (45) is provided at the first opening (421).

5. The coalbed methane horizontal well cementing device according to claim 1, characterized in that: The connection point between the second one-way valve (46) and the grouting pipe (42) is located between the first opening (421) and the second opening (422).

6. The coalbed methane horizontal well cementing device according to claim 1, characterized in that: There are a plurality of grouting pipes (42), and the plurality of grouting pipes (42) are arranged at intervals along the circumference of the technical casing (10).

7. The coalbed methane horizontal well cementing device according to claim 1, characterized in that: The distance between the outer side wall of the guide block (47) and the outer surface of the technical sleeve (10) is greater than the distance between the grouting pipe (42) and the outer surface of the technical sleeve (10).

8. The coalbed methane horizontal well cementing device according to any one of claims 1 to 7, characterized in that: The production casing (20) is a PE casing.

9. A method for cementing a coalbed methane horizontal well, characterized in that: The cementing method is implemented using the coalbed methane horizontal well cementing device according to any one of claims 1 to 8, and the cementing method includes: Lowering the coalbed methane horizontal well cementing device into the horizontal well (1); Performing a well-washing operation, and then performing a ball-dropping operation to seal the ball seat (43) of the packer (40); Pumping cement slurry from the inner cavity of the technical casing (10) into the packer bag (41) of the packer (40) so that the packer bag (41) expands and seals the annulus between the technical casing (10) and the wellbore wall of the horizontal well (1); After the cement slurry fills the packer bag (41), the pressure of the cement slurry is adjusted to be greater than the preset bursting pressure of the bursting valve (44) of the packer (40), so that the cement slurry enters the annulus between the technical casing (10) and the well wall of the horizontal well (1) and flows out to the ground, completing the grouting; The cement slurry in the inner cavity of the technical casing (10) is completely replaced with clean water of the same volume, and the technical casing (10) is closed to hold the pressure for a preset time to complete the cementing.

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