A coalbed methane L-shaped up-dip horizontal well halfway flushing device and well flushing method

Abstract

A mid-range well-washing device and method for an L-shaped, up-dip coalbed methane horizontal well. The device comprises a high-pressure hose, a well-washing string, a blowout line, and a sewage collection tank; the well-washing string comprises an oil pipe, a drill screen, a packer, a hydraulic anchor, a centralizer, and a guide cone. The present invention provides a mid-range well-washing device and method for an L-shaped, up-dip coalbed methane horizontal well, achieving excellent sand removal effectiveness, a rational structural design, simple operation, low water consumption, low construction costs, and minimal reservoir damage.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane mining, and in particular relates to a coalbed methane L-shaped up-dip horizontal well halfway flushing device and a well flushing method. Background Art

[0002] At present, the coalbed methane L-type casing horizontal well has become the main well type for coalbed methane low permeability blocks. Fracturing generally adopts the horizontal well segmentation process. The wellbore of the coalbed methane L-type casing horizontal well is mainly composed of three parts: the vertical well section, the inclined section and the horizontal section. The horizontal section is located in the coal seam as the production layer, with a length of 600 to 1000 meters. It is generally completed with P110 steel casing. In order to facilitate drainage and gas production, the outer end of the horizontal section of most coalbed methane L-type casing horizontal wells is in an upward tilt state, with an upward tilt angle of 5 0 -10 0 This results in quartz sand, coal dust, coal slime, and other materials in the formation flowing back to the lowest point in the wellbore (the landing point) and the surrounding area during the production process, causing frequent and drastic failures in drainage and production equipment. In particular, downhole pump blockages caused by quartz sand account for over 50% of all pump inspections throughout the year. Currently, the overall efficiency of horizontal well sand cleaning processes is low. Mechanical sand cleaning pumps are only suitable for vertical wells and are difficult to use for horizontal wells. While nitrogen well cleaning processes can thoroughly clean the wellbore, they have disadvantages such as high cost, long cycle times, and significant reservoir damage. Water-based fluid well cleaning also causes significant formation loss and is difficult to return.

[0003] Therefore, how to efficiently clean the quartz sand near the landing point, reduce the impact on the downhole pump, and reduce reservoir damage is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a coalbed methane L-shaped up-dip horizontal well half-way flushing device and well flushing method.

[0005] In order to achieve the above-mentioned purpose, the coalbed methane L-shaped up-dip horizontal well half-way washing device provided by the present invention includes a high-pressure hose, a well washing string, a blowout pipe line and a sewage collection tank; wherein the well washing pipe string includes an oil pipe, a drilling screen, a packer, a hydraulic anchor, a centralizer and a live guide cone; the lower part of the oil pipe is located in the coalbed methane L-shaped casing horizontal well, the upper end is located at the wellhead and is connected to one end of the high-pressure hose, and the other end of the high-pressure hose is connected to a cement pump truck; the sewage collection tank is set on the ground; the two ends of the blowout pipe line are respectively connected to the sewage collection tank and the annular space between the casing and the upper part of the oil pipe in the coalbed methane L-shaped up-dip horizontal well; the lower end of the oil pipe is connected in sequence through the drilling screen, the packer, the hydraulic anchor, the centralizer and the live guide cone.

[0006] Adjacent components in the well-washing string are connected by threads.

[0007] The outer diameter of the centralizer is larger than the outer diameters of the packer and the hydraulic anchor to ensure that the quartz sand will not be pushed to the far end of the wellbore.

[0008] The well washing method of the coalbed methane L-shaped up-dip horizontal well halfway well washing device provided by the present invention comprises the following steps performed in sequence:

[0009] 1) The lower end of the oil pipe in the coalbed methane L-shaped up-dip horizontal well half-way flushing device is connected in sequence to the drilling screen, packer, hydraulic anchor, centralizer and active guide cone to form a well flushing string;

[0010] 2) The well washing string is lowered into the L-shaped up-dip horizontal well of the coalbed methane gas with the active guide cone leading the way from the center hole of the wellhead until the active guide cone encounters resistance or is located 5-10m away from the front end of the fracturing section;

[0011] 3) Connect one end of the high-pressure hose to the upper end of the oil pipe and the other end to the cement pump truck;

[0012] 4) Start the cement pump truck and inject high-pressure well washing fluid into the oil pipe through the high-pressure hose to pressurize the seat seal packer and hydraulic anchor, so that the packer on the packer expands and seals the annular space between the casing and the oil pipe, and the anchor claws on the hydraulic anchor extend and tightly press against the inner wall of the oil pipe;

[0013] 5) Continue to inject high-pressure well washing fluid. At this time, the high-pressure well washing fluid will flow out from the holes on the drill screen, forming a high-speed water flow, thereby flushing the quartz sand, coal slime and other materials in the landing point and the surrounding area. Then, the high-pressure well washing fluid carrying quartz sand, coal slime and other materials will flow upward through the annular space between the casing and the oil pipe and flow into the blowdown line, and finally discharged into the sewage collection tank;

[0014] 6) When the discharged high-pressure well-washing fluid becomes clear, disconnect the high-pressure hose and the tubing, unseal the packer and hydraulic anchor, continue to lower the tubing to the obstructed position, repeat the above operation until the fracturing section is flushed, remove the well-washing string, and complete the operation.

[0015] The coalbed methane L-shaped up-dip horizontal well half-way flushing device and well flushing method provided by the present invention have the following beneficial effects: they are suitable for sand cleaning in coalbed methane L-shaped up-dip horizontal wells, with good cleaning effect; they have reasonable structural design, simple operation, low water consumption, low construction cost, and little damage to the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the coalbed methane L-shaped up-dip horizontal well half-well flushing device provided by the present invention. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, the coalbed methane L-shaped up-dip horizontal well half-way washing device provided by the present invention includes a high-pressure hose 1, a washing string, a blowout line 11 and a sewage collection tank 12; wherein, the washing string includes an oil pipe 4, a drilling screen 5, a packer 6, a hydraulic anchor 7, a centralizer 8 and a live guide cone 9; the lower part of the oil pipe 4 is located in the coalbed methane L-shaped casing horizontal well, the upper end is located at the wellhead 2 and is connected to one end of the high-pressure hose 1, and the other end of the high-pressure hose 1 is connected to a cement pump truck; the sewage collection tank 12 is set on the ground; the two ends of the blowout line 11 are respectively connected to the sewage collection tank 12 and the annular space between the casing 3 and the upper part of the oil pipe 4 in the coalbed methane L-shaped up-dip horizontal well; the lower end of the oil pipe 4 is connected in sequence through the drilling screen 5, the packer 6, the hydraulic anchor 7, the centralizer 8 and the live guide cone 9. The function of the active guide cone 9 is to guide the well washing string forward; the function of the centralizer 8 is to prevent the well washing string from deviating from the center of the oil pipe 4; the function of the hydraulic anchor 7 is to support the well washing string on the inner wall of the oil pipe 4; the function of the packer 6 is to seal the annular space between the casing 3 and the oil pipe 4.

[0019] Adjacent components in the well-washing string are connected by threads.

[0020] The outer diameter of the centralizer 8 is larger than the outer diameters of the packer 6 and the hydraulic anchor 7 to ensure that the quartz sand is not pushed to the far end of the casing 3 .

[0021] The well washing method using the coalbed methane L-shaped up-dip horizontal well halfway washing device provided by the present invention comprises the following steps performed in sequence:

[0022] 1) The lower end of the oil pipe 4 in the coalbed methane L-shaped up-dip horizontal well half-way flushing device is sequentially connected to the drilling screen 5, the packer 6, the hydraulic anchor 7, the centralizer 8 and the active guide cone 9 to form a well flushing string;

[0023] 2) The well-washing string is lowered into the L-shaped up-dip horizontal well of the coalbed methane gas from the center hole of the wellhead 2 with the active guide cone 9 leading in front, until the active guide cone 9 encounters resistance or is located 5-10m away from the front end of the fracturing section 10;

[0024] 3) Connect one end of the high-pressure hose 1 to the upper end of the oil pipe 4 and the other end to the cement pump truck;

[0025] 4) Start the cement pump truck and inject high-pressure well flushing fluid into the oil pipe 4 through the high-pressure hose 1, pressurizing the seat packer 6 and the hydraulic anchor 7, causing the packer on the packer 6 to expand and seal the annular space between the casing 3 and the oil pipe 4, and causing the anchor claws on the hydraulic anchor 7 to extend and tightly press against the inner wall of the oil pipe 4;

[0026] 5) Continue to inject high-pressure well-washing fluid. At this time, the high-pressure well-washing fluid will flow out from the holes on the borehole screen 5, forming a high-speed water flow, thereby flushing the quartz sand, coal slime and other materials in the landing point and the surrounding area. The high-pressure well-washing fluid carrying quartz sand, coal slime and other materials will then flow upward through the annular space between the casing 3 and the oil pipe 4 and flow into the blowdown line 11, and finally discharged into the wastewater collection tank 12;

[0027] 6) When the discharged high-pressure well-washing fluid becomes clear, disconnect the high-pressure hose 1 and the oil pipe 4, unseal the packer 6 and the hydraulic anchor 7, and continue to lower the oil pipe 4 to the obstruction position. Repeat the above operation until the vicinity of the fracturing section 10 is flushed, and the well-washing string is removed to complete the operation.

Claims

1. A coalbed methane L-shaped up-dip horizontal well halfway flushing device, characterized by: The coalbed methane L-shaped upward-inclined horizontal well halfway washing device comprises a high-pressure hose (1), a washing string, a blowout line (11) and a sewage collection tank (12); wherein the washing string comprises an oil pipe (4), a drilling screen (5), a packer (6), a hydraulic anchor (7), a centralizer (8) and a live guide cone (9); the lower part of the oil pipe (4) is located in the coalbed methane L-shaped casing horizontal well, the upper end is located at the wellhead (2) and is connected to one end of the high-pressure hose (1). The ends of the high-pressure hose (1) are connected, and the other end of the high-pressure hose (1) is connected to a cement pump truck; a sewage collection tank (12) is set on the ground; the two ends of the blowdown line (11) are respectively connected to the sewage collection tank (12) and the annular space between the casing (3) and the upper part of the oil pipe (4) in the L-shaped upward-inclined horizontal well of coalbed methane; the lower end of the oil pipe (4) is connected in sequence through a drilling screen (5), a packer (6), a hydraulic anchor (7), a centralizer (8) and a live guide cone (9).

2. The coalbed methane L-shaped up-dip horizontal well halfway flushing device according to claim 1 is characterized in that: Adjacent components in the well-washing string are connected by threads.

3. The coalbed methane L-shaped upward-inclined horizontal well halfway flushing device according to claim 1 is characterized in that: The outer diameter of the centralizer (8) is larger than the outer diameters of the packer (6) and the hydraulic anchor (7).

4. A well washing method using the coalbed methane L-shaped up-dip horizontal well halfway washing device according to any one of claims 1 to 3, characterized in that: The well washing method comprises the following steps performed in sequence: 1) The lower end of the oil pipe (4) in the coalbed methane L-shaped upward horizontal well half-way well washing device is sequentially connected to the drilling screen (5), the packer (6), the hydraulic anchor (7), the centralizer (8) and the active guide cone (9) to form a well washing pipe string; 2) The well washing pipe string is lowered into the coalbed methane L-shaped upward-inclined horizontal well from the center hole of the wellhead (2) in a manner guided by the active guide cone (9) until the active guide cone (9) encounters resistance or is located 5-10m away from the front end of the fracturing section (10); 3) Connect one end of the high-pressure hose (1) to the upper end of the oil pipe (4), and the other end to the cement pump truck; 4) Start the cement pump truck and inject high-pressure well-washing fluid into the oil pipe (4) through the high-pressure hose (1), thereby pressurizing the seat packer (6) and the hydraulic anchor (7), causing the packer on the packer (6) to expand and seal the annular space between the casing (3) and the oil pipe (4), and causing the anchor claws on the hydraulic anchor (7) to extend and tightly press against the inner wall of the oil pipe (4); 5) Continue to inject high-pressure well washing fluid. At this time, the high-pressure well washing fluid will flow out from the holes on the drilling screen (5), forming a high-speed water flow, thereby washing the quartz sand, coal slime and other materials at the landing point and the surrounding area. Then, the high-pressure well washing fluid carrying the quartz sand, coal slime and other materials will flow upward through the annular space between the casing (3) and the oil pipe (4) and flow into the blowdown line (11), and finally discharged into the sewage collection tank (12); 6) When the discharged high-pressure well-washing fluid becomes clear, disconnect the high-pressure hose (1) and the oil pipe (4), unseal the packer (6) and the hydraulic anchor (7), and continue to lower the oil pipe (4) to the obstructed position. Repeat the above operation until the fracturing section (10) is flushed, and the well-washing string is removed to complete the operation.

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