Half-path well washing device and method for coal bed gas L-shaped updip horizontal well

Abstract

The invention discloses a coal bed gas L-shaped updip horizontal well half-pass well washing device and a well washing method. The device comprises a high-pressure hose, a well washing pipe column, an open flow pipeline and a sewage collecting tank. The well washing pipe column comprises an oil pipe, a drilling screen pipe, a packer, a hydraulic anchor, a centralizer and a movable guide cone. The coal bed gas L-shaped updip horizontal well half-pass well washing device and the well washing method have the following beneficial effects that the device and the method are suitable for coal bed gas L-shaped updip horizontal well sand cleaning, and the cleaning effect is good; the structure design is reasonable, the operation is simple, the water consumption is low, the construction cost is low, and the damage to the reservoir is small.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane mining, and particularly relates to a coalbed methane L-shaped upward-inclined horizontal well half-way well washing device and a well washing method. Background Art

[0002] At present, the L-type casing horizontal well of coalbed methane has become the main well type for coalbed methane low permeability blocks. Fracturing generally adopts the horizontal well segmentation process. The wellbore of the L-type casing horizontal well of coalbed methane 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. Generally, P110 steel casing is put into the well for completion. In order to facilitate drainage and gas production, the outer end of the horizontal section of most L-type casing horizontal wells of coalbed methane is in an upward tilt state, with an upward tilt angle of 5 0 -10 0 This results in the quartz sand, coal powder, coal slime and other materials in the formation flowing back to the lowest point in the wellbore, i.e. the landing point and nearby areas during the production process, causing frequent and surging failures of drainage equipment. In particular, downhole pump blockages caused by quartz sand account for more than 50% of the total number of pump well inspections throughout the year. At present, the overall efficiency of horizontal well sand cleaning technology is low. Among them, mechanical sand cleaning pumps are only suitable for vertical wells, but it is difficult to use them for horizontal well cleaning. Although nitrogen well cleaning and other processes can thoroughly clean the wellbore, they have the disadvantages of high cost, long cycle, and great reservoir damage. Water-based fluid well cleaning has serious formation leakage 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 technical personnel in this field. Summary of the invention

[0004] In order to solve the above problems, the object of the present invention is to provide a half-way well washing device and a well washing method for an L-shaped upward-inclined horizontal well of coalbed methane.

[0005] In order to achieve the above-mentioned purpose, the coalbed methane L-shaped up-dip horizontal well half-way well washing device provided by the present invention comprises a high-pressure hose, a well washing pipe string, a blowout pipe line and a sewage collection tank; wherein the well washing pipe string comprises an oil pipe, a drilling screen pipe, 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 arranged 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 pipe, the packer, the hydraulic anchor, the centralizer and the live guide cone.

[0006] Adjacent components in the well-washing pipe 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 upward-inclined horizontal well half-way 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 half-way well washing device of the L-shaped upward-inclined horizontal well of coalbed methane is connected to the drilling screen, the packer, the hydraulic anchor, the centralizer and the active guide cone in sequence to form a well washing pipe string;

[0010] 2) The well washing pipe string is lowered into the L-shaped upward-inclined horizontal well of coalbed methane from the center hole of the wellhead with the active guide cone leading in front, 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 packer and hydraulic anchor, so that the packer on the packer expands to seal the annular space between the casing and the oil pipe, and the anchor claw on the hydraulic anchor extends and tightly presses 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 drilling screen to form a high-speed water flow, thereby washing the quartz sand, coal slime and other materials in the landing point and nearby areas. 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, release the connection between 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 it is flushed to the vicinity of the fracturing section, remove the well-washing string, and complete the construction.

[0015] The coalbed methane L-shaped upward-inclined horizontal well half-way well-washing device and well-washing method provided by the present invention have the following beneficial effects: they are suitable for sand cleaning in coalbed methane L-shaped upward-inclined horizontal wells, and have 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 A schematic diagram of a half-way well flushing device for a coalbed methane L-shaped up-dip horizontal well provided by the present invention. DETAILED DESCRIPTION

[0017] The present invention is 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 well washing device provided by the present invention comprises a high-pressure hose 1, a well washing pipe string, a blowout pipe line 11 and a sewage collection tank 12; wherein, the well washing pipe string comprises an oil pipe 4, a drilling screen pipe 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 arranged on the ground; the two ends of the blowout pipe 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 pipe 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 pipe string forward; the function of the centralizer 8 is to prevent the well-washing pipe string from deviating from the center of the oil pipe 4; the function of the hydraulic anchor 7 is to support the well-washing pipe 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 pipe 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 half-way well 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 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;

[0023] 2) The well-washing pipe string is lowered from the central hole of the wellhead 2 into the L-shaped upward-inclined horizontal well of the coalbed methane 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, inject high-pressure well washing fluid into the oil pipe 4 through the high-pressure hose 1, pressurize the seat packer 6 and the hydraulic anchor 7, so that the packer on the packer 6 expands to seal the annular space between the casing 3 and the oil pipe 4, and the anchor claw on the hydraulic anchor 7 extends and tightly presses 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 to form a high-speed water flow, thereby washing 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 pass upward through the annular space between the casing 3 and the oil pipe 4 and flow into the blowdown line 11, and finally be discharged into the sewage collection tank 12;

[0027] 6) When the discharged high-pressure well-washing fluid becomes clear, the connection between the high-pressure hose 1 and the oil pipe 4 is released, the packer 6 and the hydraulic anchor 7 are unsealed, and the oil pipe 4 is continued to be lowered to the obstructed position. The above operation is repeated until the vicinity of the fracturing section 10 is flushed, and the well-washing string is taken out to complete this operation.

Claims

1. A coalbed methane L-shaped upward horizontal well halfway flushing device, characterized by: The coalbed methane L-shaped upward-inclined horizontal well halfway well-washing device comprises a high-pressure hose (1), a well-washing pipe string, a blowout pipe line (11) and a sewage collection tank (12); wherein the well-washing pipe string comprises an oil pipe (4), a drilling screen pipe (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 arranged 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 upward horizontal well halfway flushing device according to claim 1 is characterized by: Adjacent components in the well-washing pipe string are connected by threads.

3. The coalbed methane L-shaped upward horizontal well halfway flushing device according to claim 1 is characterized by: The outer diameter of the centralizer (8) is greater 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 half-way well 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 from the center hole of the wellhead (2) into the L-shaped upward-inclined horizontal well of the coalbed methane 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); 3) Connect one end of the high-pressure hose (1) to the upper end of the oil pipe (4), and connect the other end to the cement pump truck; 4) Turn on the cement pump truck, inject high-pressure well-washing fluid into the oil pipe (4) through the high-pressure hose (1), pressurize the seat packer (6) and the hydraulic anchor (7), so that the packer on the packer (6) expands to seal the annular space between the casing (3) and the oil pipe (4), and the anchor claw on the hydraulic anchor (7) extends and tightly presses 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 borehole screen (5) to form a high-speed water flow, thereby washing the quartz sand, coal slime and other substances at the landing point and the surrounding area. Then, the high-pressure well-washing fluid carrying the quartz sand, coal slime and other substances 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, the connection between the high-pressure hose (1) and the oil pipe (4) is released, the packer (6) and the hydraulic anchor (7) are unsealed, and the oil pipe (4) is continued to be lowered to the obstructed position. The above operation is repeated until the vicinity of the fracturing section (10) is flushed, and the well-washing string is taken out to complete the operation.

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