Coal bed gas drilling wall stabilizing device and construction method

Abstract

The present application provides a kind of coal bed gas drilling solid wall device and construction method, including bearing device, support device, flow cone and grouting device, the support device, flow cone and grouting device are all installed on drill pipe by bearing;The bearing device is set in the outside of drill pipe, for establishing axial connection with drill pipe and providing vertical support;The support device is arranged in the axial side of the bearing device, and the well wall is supported by hydraulic mode to fix the device;The flow cone is the open downward conical through-hole cylinder, the flow cone is arranged in the axial side of the support device away from the bearing device;The grouting device is arranged in the axial side of the flow cone away from the support device.The present application solves the construction difficulties such as sticking, hole collapse, mud loss, large hole deviation in coal bed gas drilling construction.

Description

Technical Field

[0001] This invention belongs to the field of coalbed methane extraction technology, specifically relating to a coalbed methane drilling wall stabilization device and construction method. Background Technology

[0002] my country possesses abundant coalbed methane (CBM) resources, with geological resources of approximately 30 trillion m³ at depths shallower than 2000 meters and recoverable resources of about 10 trillion m³. These resources are mainly distributed across four gas-bearing regions: Shanxi-Shaanxi, Inner Mongolia, Xinjiang, Hebei-Henan-Anhui, and Yunnan-Guizhou-Sichuan, with the Qinshui Basin and Ordos Basin being the primary producing areas. However, the following problems exist during CBM exploration and development drilling: First, the geological formations encountered are complex and variable, frequently leading to stuck drill pipe. Second, as drilling depth increases, the mud wall protection effect becomes ineffective, resulting in open-hole wells and frequent occurrences of borehole collapse and leakage. Third, wellbore trajectory control is difficult; excessively long drill pipes make it difficult to control the deviation during drilling, resulting in excessive wellbore deviation and large errors from the designed target drilling point, failing to meet wellbore quality requirements. These issues seriously affect CBM exploration and development. Summary of the Invention

[0003] To address the problems in the prior art, this invention provides a coalbed methane drilling wall stabilization device and construction method, which can provide stable mechanical support during the drilling process, achieve high-quality wall stabilization operations, and solve construction problems such as stuck drill bit, wellbore collapse, mud loss, and large wellbore deviation in coalbed methane drilling.

[0004] The technical problem solved by this invention is achieved by the following technical solution: The first objective of this invention is to provide a coalbed methane drilling wall stabilization device, comprising a bearing device, a support device, a guide cone, and a grouting device, wherein the support device, the guide cone, and the grouting device are all mounted on the drill pipe via bearings; The bearing device is sleeved on the outside of the drill pipe and is used to establish an axial connection with the drill pipe and provide vertical support. The support device is located on one axial side of the bearing device and is hydraulically tightened against the well wall to fix the device. The guide cone is a cone-shaped cylinder with a downward-facing opening, and the guide cone is located on the side of the support device that is axially away from the bearing device; The grouting device is located on the side of the guide cone axially away from the support device. The grouting device includes a hydraulic telescopic assembly fixed to the bearing and a grouting template covering the outside of the hydraulic telescopic assembly. The grouting template includes a flexible sealing wall covering the outside of the hydraulic telescopic assembly and a baffle plate disposed at the bottom of the sealing wall. The baffle plate is in close contact with the well wall when the hydraulic telescopic assembly is extended. The bottom of the flexible sealing wall is fixedly connected to the inner wall of the baffle plate, so that the flexible sealing wall, the baffle plate, and the well wall form an isolated grouting cavity. The grouting device also includes a grouting pipe communicating with the grouting cavity.

[0005] Furthermore, the bearing device is a hollow cylindrical tube, and the outer diameter of the bearing device is larger than the inner diameter of the bearing.

[0006] Furthermore, the bearing device is connected to the drill pipe via a threaded connection.

[0007] Furthermore, the support device is a multi-arm hydraulic piston assembly, which is connected to a hydraulic pump station via a first hydraulic pipe.

[0008] Furthermore, the multi-arm hydraulic piston assembly has at least three components.

[0009] Furthermore, the hydraulic telescopic assembly is a radially retractable piston-type or telescopic hydraulic telescopic assembly, and the hydraulic telescopic assembly is connected to a hydraulic pump station through a second hydraulic pipe.

[0010] Furthermore, the flexible sealing wall and baffle are both double-arc sliding variable diameter pipes. The diameter of the grouting template is scaled up or down as the length of the overlapping part of the two semi-circular pipes that are fitted together changes. The grouting template is a diameter-reducing ring with variable diameter.

[0011] Furthermore, there are multiple hydraulic telescopic components, each including two symmetrically arranged hydraulic jacks, each hydraulic jack being connected to an arc-shaped sliding reducer pipe.

[0012] Furthermore, a plurality of conical nails are provided on the upper surface of the baffle plate.

[0013] Furthermore, the flexible sealing wall is also provided with vent holes.

[0014] Furthermore, a spray pipe is provided on the top of the flexible sealing wall, and the spray pipe is connected to a stripping liquid conduit.

[0015] The second objective of this invention is to provide a coalbed methane drilling construction method, utilizing the aforementioned wall-stabilizing device, comprising the following steps: S1. Start the drilling rig to drill to a certain position, start the hydraulic pump to open the support device through the first hydraulic pipe, so that the wall-fixing device forms a support with the well wall; S2. Open the second hydraulic pipe and under the liquid pressure of the hydraulic pump, open the hydraulic telescopic component to make the two arc-shaped sliding variable diameter pipes of the grouting template move relative to each other until the baffle is tightly attached to the well wall. S3. Spray the release agent through the release agent conduit to evenly spray the surface of the grouting template with the release agent. Open the grouting pipe to grout until the grouting mold cavity is filled with cement grout. Stop grouting and wait for the cement grout to set. S4. Unload the support device and hydraulic telescopic assembly. Under the action of gravity, the wall-fixing device slides down to the bearing device. Restart the hydraulic pump to open the support device and hydraulic telescopic assembly, and repeat step S3 for grouting. S5. Repeat step S4 until the work section is completed. Pull the drill pipe, wall-stabilizing device, and drill bit to the surface to replace the drill bit and drill pipe. Then repeat steps S1-S4 until the drilling work is completed.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: The wall-stabilizing device of this invention is mounted on the drill pipe via bearings. During construction, it drills along with the drill pipe but does not rotate with it, achieving simultaneous drilling and cementing operations to form a stable wellbore. The semi-conical guiding structure of the guide cone optimizes the flow path of the drilling mud, ensuring that cuttings and mud can smoothly return to the surface along the inside of the device, reducing the formation of cuttings beds. Through the supporting action of the hydraulic telescopic components and support devices, the drill pipe maintains good centering during operation, ensuring a smooth wellbore trajectory and reducing wellbore deviation.

[0017] The grouting device of this invention adopts a retractable support structure and the size of the baffle can be adjusted as needed, which enhances the adaptability of the device and the flexibility of field application; at the same time, the radial support force provided by the hydraulic telescopic component realizes the wrapping and reinforcement of the well wall during grouting, which significantly improves the regularity of the coal seam section and fundamentally solves the problems of stuck drill and narrow-diameter stuck drill.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the construction state structure of a coalbed methane drilling wall-stabilizing device according to the present invention.

[0020] Figure 2 This is a schematic diagram of the wall-solidifying device in a coalbed methane drilling wall-solidifying device according to the present invention.

[0021] Figure 3 This is a schematic diagram of the grouting device in a coalbed methane drilling wall-stabilizing device according to the present invention.

[0022] Figure 4 This is a schematic diagram of the support device in a coalbed methane drilling wall-stabilizing device according to the present invention.

[0023] In the attached diagram, 1 is the drill pipe, 2 is the well wall, 3 is the wall-stabilizing cement, 4 is the bearing, 5 is the wall-stabilizing device, 6 is the grouting device, 7 is the guide cone, 8 is the support device, 9 is the bearing device, 10 is the drill bit, 11 is the demolding fluid conduit, 12 is the grouting pipe, 13 is the first hydraulic pipe, 14 is the hydraulic telescopic assembly, 15 is the baffle, 16 is the grouting mold cavity, 17 is the flexible sealing wall, 18 is the second hydraulic pipe, 19 is the multi-arm hydraulic piston assembly, 20 is the conical nail, 21 is the vent hole, and 22 is the spray pipe. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0025] In addition, unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or prepared by existing methods.

[0026] Example 1: A coalbed methane drilling wall stabilization device A coalbed methane drilling wall-stabilizing device 5 includes a bearing device 9, a support device 8, a guide cone 7, and a grouting device 6. The support device 8, the guide cone 7, and the grouting device 6 are all mounted on the drill pipe 1 via bearings 4. The bearing device 9 is fitted outside the drill pipe 1 to establish an axial connection with the drill pipe 1 and provide vertical support; The support device 8 is located on one axial side of the bearing device 9 and is hydraulically tightened against the well wall to fix the device. The guide cone 7 is a cone-shaped cylinder with a downward-facing opening, and the guide cone 7 is located on the side of the support device 8 that is axially away from the bearing device 9; The grouting device 6 is located on the side of the guide cone 7 away from the support device 8. The grouting device 6 includes a hydraulic telescopic assembly 14 fixed on the bearing 4 and a grouting template covering the outside of the hydraulic telescopic assembly 14. The grouting template includes a flexible sealing wall 17 covering the outside of the hydraulic telescopic assembly 14 and a baffle 15 located at the bottom of the flexible sealing wall. When the hydraulic telescopic assembly 14 is opened, the baffle 15 is tightly attached to the well wall. The bottom of the flexible sealing wall 17 is fixedly connected to the inner wall of the baffle 15, so that the flexible sealing wall 17, the baffle 15 and the well wall form an isolated grouting cavity 16. The grouting device 6 also includes a grouting pipe 12 communicating with the grouting cavity 16.

[0027] The bearing device 9 is threadedly connected to the drill pipe 1 and is located at the bottom of the wall-stabilizing device 5, so that the wall-stabilizing device 5 can be stably supported in the vertical direction; the support device 8 forms effective support with the well wall through hydraulic means; the guide cone 7 adopts a frustum-shaped guide structure to guide the mud to flow into the device and return to the surface mud pool; when in use, the grouting device 6 forms an isolated grouting cavity 16 between the flexible sealing wall 17, the baffle 15, and the well wall, and forms a hollow cylinder inside the flexible sealing wall 17. During use, the inner diameter of the flexible sealing wall 17 can be adjusted according to the wellbore diameter.

[0028] To better provide support and stability, the bearing device 9 is a hollow cylindrical tube with an outer diameter larger than the inner diameter of the bearing 4. The bearing device 9 is connected to the drill rod 1 via a threaded connection. This connection not only transmits torque but, more importantly, bears the weight of the entire wall-fixing device 5, providing a vertical support point. For optimal support, the bearing device 9 is made of high-strength alloy steel.

[0029] The support device 8 is a multi-arm hydraulic piston assembly 19, which is connected to a hydraulic pump station via a first hydraulic pipe 13.

[0030] The multi-arm hydraulic piston assembly has at least three components. In a preferred embodiment, the multi-arm hydraulic piston assembly 19 consists of three evenly distributed hydraulic pistons. The first hydraulic pipe 13 is a tubular structure parallel to the drill pipe 1, extending along the drill pipe 1 to the hydraulic pump station on the surface. When support is required, the hydraulic pump station is activated and pressurized, causing the multi-arm hydraulic piston assembly to extend and its ends to press against the well wall, thereby anchoring the entire device downhole and preventing axial movement under grouting forces.

[0031] The hydraulic telescopic assembly 14 is a radially retractable piston-type or telescopic hydraulic telescopic assembly. The hydraulic telescopic assembly 14 is connected to the hydraulic pump station via a second hydraulic pipe 18. The second hydraulic pipe 18 is set parallel to the drill pipe 1 and connected to the hydraulic pump station on the ground. When grouting is required, the hydraulic pump station is activated and pressurized. Under the pressure, the hydraulic telescopic assembly 14 extends, causing the baffle 15 to abut against the well wall, thereby forming a sealed grouting cavity 16 between the well wall 2, the baffle 15, and the flexible sealing wall 17.

[0032] Both the flexible sealing wall 17 and the baffle 15 are double-arc sliding reducing pipes. The diameter of the grouting template changes accordingly as the length of the overlapping part of the two semicircular pipes that are fitted together changes. The grouting template is a reducing ring with a variable diameter. When the hydraulic telescopic component 14 extends under pressure, the two opposing arc-shaped sliding reducing pipes move relative to each other, causing the length of the overlapping part of the two semicircular pipes to decrease, the inner diameter of the flexible sealing wall 17 to gradually increase, and the baffle 15 to get closer and closer to the well wall; conversely, the opposite occurs when the hydraulic telescopic component 14 retracts.

[0033] There are multiple hydraulic telescopic components 14, each including two symmetrically arranged hydraulic jacks, each connected to an arc-shaped sliding reducer. The hydraulic telescopic components 14 are fixed to the drill rod 1 by bearings 4, so that the grouting device 6 does not rotate when the drill rod 1 rotates. The two hydraulic jacks on each hydraulic telescopic component 14 are symmetrically arranged on both sides of the bearing 4.

[0034] To ensure the grouting effect, in a preferred embodiment, the height of the grouting mold cavity 16 is preferably 3cm, thereby ensuring that the drilling work can continue.

[0035] Multiple conical nails 20 are provided on the upper surface of the baffle 15, so that the grouting structure in the front section and the grouting structure in the back section can form an overlapping section, thereby making the grouting structure more tightly and stably connected, and making the cementing cement form a stable and effective whole from top to bottom.

[0036] The flexible sealing wall 17 is also provided with an exhaust port 21.

[0037] A spray pipe 22 is installed at the top of the flexible sealing wall 17, and the spray pipe 22 is connected to a release agent conduit 11. Before grouting, the release agent is sprayed through the release agent conduit 11. The release agent is sprayed out from the top spray pipe 22, so that the release agent can be evenly sprayed from top to bottom on the surface of the grouting template, reducing the adhesion between the grouting template and the cement grout, and making it easier to retract the grouting template for the next section of grouting.

[0038] Example 2: A method for drilling coalbed methane wells A coalbed methane drilling construction method, utilizing the wall-fixing device of Example 1, includes the following steps: S1. Based on existing geological data, a sweet spot for coalbed methane exploration and development is selected, and target well locations are chosen. This example takes the No. 15 coal seam of the Taiyuan Formation in the northeastern Qinshui Basin as an example. The roof and floor are mainly composed of limestone, sandy mudstone, and mudstone. The coal seam thickness ranges from 4.30 to 8.25 m, with an average thickness of 5.35 m. The burial depth ranges from 244 to 580 m, with an average burial depth of 389 m, which is considered medium to shallow burial depth. The reservoir pressure is relatively low, averaging 0.67 MPa, and the gas content ranges from 2.61 to 19.50 m³ / t, with an average gas content of 9.37 m³ / t. It has strong adsorption capacity, with an average Langmuir pressure of 36.65 m³ / t. The permeability and porosity are relatively poor, with an average permeability of 0.029 mD and an average porosity of 5%. The coal body structure is stable, providing excellent conditions for coalbed methane development.

[0039] Using a vertical well drilling process, the drilling rig is started initially with a φ311mm drill bit 10, followed by a φ273mm drill bit 10 for drilling operations. Drilling is then performed to a depth of 6m using the φ311mm drill bit 10. During drilling, the wall-stabilizing device 5 does not move with the drill pipe 1; it is mounted on the drill pipe 1. The drilling rig is then started again, with a drilling pressure of 10-60kN, a rotation speed of 110r / min, and a displacement of 15-20L / s, drilling to a depth of 15 meters above the surface. The hydraulic pump is then started, opening the support device 8 through the first hydraulic pipe 13, allowing the wall-stabilizing device 5 to support the well wall.

[0040] In this embodiment, the wall-fixing device 5 is fixed 105m away from the drill bit. The supporting device 9 is a hollow cylinder with a diameter of 180mm and a length of 1000mm.

[0041] S2. Open the second hydraulic pipe 18. Under the liquid pressure of the hydraulic pump, the hydraulic telescopic component 14 is opened, causing the two arc-shaped sliding reducing pipes of the grouting template to move relative to each other until the baffle 15 is tightly attached to the well wall.

[0042] S3. Spray the release agent evenly onto the surface of the grouting template through the release agent conduit. Open the grouting pipe 12 to grout until the grouting mold cavity 16 is filled with cement slurry. Stop grouting and wait for the cement slurry to set. In this embodiment, G-grade oil well cementing quick-setting cement is used.

[0043] S4. Unload the support device 8 and hydraulic telescopic component 14. Under the action of gravity, the wall-fixing device 5 slides down to the bearing device 9. Restart the hydraulic pump to open the support device 8 and hydraulic telescopic component 14, and repeat step S3 for grouting. Each drilling distance is 6m, and the grouting device 6 overlaps with the previous section by 30cm.

[0044] S5. Repeat step S4 until the work section is completed. Pull out drill pipe 1, wall-stabilizing device 5, and drill bit 10 to the ground, replace drill bit 10 and drill pipe 1, and then repeat steps S1-S4 until the drilling work is completed. Finally, a layer of wall-stabilizing cement 3 is formed on the well wall.

[0045] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0046] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A coalbed methane drilling wall stabilization device, characterized in that: It includes a bearing device, a support device, a guide cone, and a grouting device, all of which are mounted on the drill pipe via bearings; The bearing device is sleeved on the outside of the drill pipe and is used to establish an axial connection with the drill pipe and provide vertical support. The support device is located on one axial side of the bearing device and is hydraulically tightened against the well wall to fix the device. The guide cone is a cone-shaped cylinder with a downward-facing opening, and the guide cone is located on the side of the support device that is axially away from the bearing device; The grouting device is located on the side of the guide cone axially away from the support device. The grouting device includes a hydraulic telescopic assembly fixed to the bearing and a grouting template covering the outside of the hydraulic telescopic assembly. The grouting template includes a flexible sealing wall covering the outside of the hydraulic telescopic assembly and a baffle plate disposed at the bottom of the sealing wall. The baffle plate is in close contact with the well wall when the hydraulic telescopic assembly is extended. The bottom of the flexible sealing wall is fixedly connected to the inner wall of the baffle plate, so that the flexible sealing wall, the baffle plate, and the well wall form an isolated grouting cavity. The grouting device also includes a grouting pipe communicating with the grouting cavity.

2. The coalbed methane drilling wall-stabilizing device as described in claim 1, characterized in that: The support device is a multi-arm hydraulic piston assembly, which is connected to a hydraulic pump station via a first hydraulic pipe.

3. The coalbed methane drilling wall-stabilizing device as described in claim 2, characterized in that: The multi-arm hydraulic piston assembly has at least three components.

4. The coalbed methane drilling wall-stabilizing device as described in claim 1, characterized in that: The hydraulic telescopic assembly is a radially retractable piston-type or telescopic hydraulic telescopic assembly, and the hydraulic telescopic assembly is connected to a hydraulic pump station through a second hydraulic pipe.

5. The coalbed methane drilling wall-stabilizing device as described in claim 4, characterized in that: The flexible sealing wall and baffle are both double arc sliding variable diameter pipes. The diameter of the grouting template is scaled up or down as the length of the overlapping part of the two semi-circular pipes that are fitted together changes. The grouting template is a diameter-reducing ring with a variable diameter.

6. The coalbed methane drilling wall-stabilizing device as described in claim 5, characterized in that: The hydraulic telescopic assembly comprises multiple components, including two symmetrically arranged hydraulic jacks, each of which is connected to an arc-shaped sliding reducer pipe.

7. The coalbed methane drilling wall stabilization device as described in claim 1, characterized in that: The upper surface of the baffle is provided with multiple conical nails.

8. The coalbed methane drilling wall-stabilizing device as described in claim 1, characterized in that: A spray pipe is installed on the top of the flexible sealing wall, and the spray pipe is connected to a stripping liquid conduit.

9. A method for drilling coalbed methane wells, characterized in that, Using the wall-fixing device according to any one of claims 1-8, the method includes the following steps: S1. Start the drilling rig to drill to a certain position, start the hydraulic pump to open the support device through the first hydraulic pipe, so that the wall-fixing device forms a support with the well wall; S2. Open the second hydraulic pipe and under the liquid pressure of the hydraulic pump, open the hydraulic telescopic component to make the two arc-shaped sliding variable diameter pipes of the grouting template move relative to each other until the baffle is tightly attached to the well wall. S3. Spray the release agent through the release agent conduit to evenly spray the surface of the grouting template with the release agent. Open the grouting pipe to grout until the grouting mold cavity is filled with cement grout. Stop grouting and wait for the cement grout to set. S4. Unload the support device and hydraulic telescopic assembly. Under the action of gravity, the wall-fixing device slides down to the bearing device. Restart the hydraulic pump to open the support device and hydraulic telescopic assembly, and repeat step S3 for grouting. S5. Repeat step S4 until the work section is completed. Pull the drill pipe, wall-stabilizing device, and drill bit to the surface to replace the drill bit and drill pipe. Then repeat steps S1-S4 until the drilling work is completed.

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