WO2020087862A1

WO2020087862A1 - Device for simulating pressure relief of in-situ coalbed methane horizontal well in tectonically-deformed coal, and simulation method

Info

Publication number: WO2020087862A1
Application number: PCT/CN2019/080716
Authority: WO
Inventors: 刘世奇; 桑树勋; 王冉; 曹丽文; 王海文; 周效志; 黄华州; 高德燚; 贾金龙; 徐宏杰; 刘会虎; 李自成; 刘长江; 方辉煌; 王鹤
Original assignee: 中国矿业大学; 奥理文地质科技（徐州）有限公司
Priority date: 2018-10-29
Filing date: 2019-04-01
Publication date: 2020-05-07
Also published as: CN109632625B; CN109632625A

Abstract

A device for simulating pressure relief of an in-situ coalbed methane horizontal well in tectonically-deformed coal, and a simulation method. A high-pressure pulsating fluid injection module comprises a hydraulic pump (2), a hydraulic cylinder (5), a high-modulus spring (6), an impact pressure cavity (9), and a constant-speed constant-pressure pump (14). The hydraulic pump (2) and the hydraulic cylinder (5) are in hydraulic connection. A right end of a guide rod (7) is fixedly connected to a right installation plate of the high-modulus spring (6), and a left end thereof passes through a left installation plate of the high-modulus spring (6). An electromagnetic clutch (11) is disposed between a piston rod of the hydraulic cylinder (5) and the guide rod (7). A left end of an impact piston (10) in the impact pressure cavity (9) is fixedly connected to the right installation plate of the high-modulus spring (6). The impact pressure cavity (9) is in communication with an outlet of the constant-speed constant-pressure pump (14), and has an outlet pipe in communication with a downhole jetting module. The right installation plate of the high-modulus spring (6) is provided with a displacement sensor (8). The downhole jetting module is disposed within a material similar to a coal bed. The device and the method simulate stress relief of a horizontal well (19.2) in a coal reservoir having a soft structure, so as to provide guidance and a basis for pressure relief and permeability enhancement in actual mining of in-situ coalbed methane in tectonically-deformed coal.

Description

Pressure relief test device and test method for structural coal in-situ coal bed methane horizontal well

Technical field

The invention relates to a coal bed methane horizontal well pressure relief test device and test method, in particular to a structure coal in-situ coal bed methane horizontal well pressure relief test device and test method, which belongs to the field of coal bed methane mining.

Background technique

Tectonic coal refers to coal that is subjected to tectonic stress, and the original structure and structure are damaged by strong cracks, resulting in fracture, crumpling, and polishing surface. The extensive development of tectonic coal and the richness of tectonic coal and CBM resources are the distinguishing characteristics of China ’s coal and CBM resources. Tectonic coal resources account for a high proportion of China ’s discovered coal resources, and tectonic coal CBM resources account for the country ’s total CBM resources. The proportion is greater. Structural coal has outburst characteristics such as rich gas, low permeability, and softness. Most of them are coal and gas outburst coal seams. Due to the great harm and the difficulty of extraction and utilization, coal mines often discharge their wind into the atmosphere to efficiently develop coal seam gas. It has very outstanding significance for energy, safety and ecology.

The method based on the theory of hydrophobic decompression desorption gas production is currently the main method of in-situ CBM surface well development. Due to the extremely low permeability of the structural coal reservoir and the poor effectiveness of the hydraulic fracturing and other transformation methods, the theory of hydrophobic decompression desorption gas production It is not suitable for use in structural coal reservoirs. The exploration and development practice results also show that the CBM exploration and development technologies based on the theory of hydrophobic decompression and desorption gas production include the SVR technology series (straight well fracturing, U-shaped wells, multi-branch horizontal wells, Horizontal well fracturing, etc.), the ECBM technology series (CO ₂ -ECBM, N ₂ -ECBM, etc.) and their composite technologies cannot achieve the efficient development of structural coal-bed methane. Therefore, the construction of coalbed methane efficient exploration and development technology and equipment has become one of the important technical bottlenecks restricting the rapid scale development of China's coalbed methane industry.

With the in-depth study of coal bed methane mining technology, the protection layer structure coal seam gas mining pressure relief and permeation development theory of coal mine area provides new ideas for the in situ mining of coal seam gas in structured coal. The pressure relief and permeability enhancement test device and method for in-situ coal-bed methane wells in tectonic coal are of great theoretical guiding significance for realizing the in-situ coal-bed methane horizontal well collapse hole-making cave test of tectonic coal. Technical bottlenecks for efficient development of wells lay the foundation for theoretical and practical production guidance.

Summary of the invention

In order to solve the above problems, the present invention provides a pressure relief test device and test method for structural coal in-situ coal bed methane horizontal wells, which can simulate the collapse of horizontal wells to create caves and stress relief in horizontal wells of soft structure coal reservoirs. Provide guidance for the actual gas extraction, pressure relief and permeability enhancement.

In order to achieve the above object, the present invention adopts the following technical solution: a pressure relief test device for constructing coal in-situ coal bed methane horizontal wells, including a high-pressure pulsating fluid injection module and a downhole injection module. The high-pressure pulsating fluid injection module includes a hydraulic pump, Hydraulic cylinder, high modulus spring, impact pressure chamber and constant speed constant pressure pump, the hydraulic pump is hydraulically connected to the hydraulic cylinder, the right end of the guide rod is fixedly connected to the right mounting plate of the high modulus spring, and the left end passes through the high mold The left mounting plate of the measuring spring is slidingly connected to it, the piston rod of the hydraulic cylinder is arranged coaxially with the guide rod, and an electromagnetic clutch is arranged between the end surface of the piston rod of the hydraulic cylinder and the left end surface of the guide rod; the left end of the impact piston in the impact pressure chamber extends Out of the impact pressure chamber and fixed connection with the right mounting plate of the high modulus spring, the cavity of the impact pressure chamber communicates with the outlet of the constant speed and constant pressure pump, the outlet pipeline of the impact pressure chamber communicates with the downhole injection module; the outlet of the hydraulic pump There is a pressure sensor 1 on the pipeline, a displacement sensor is installed on the right mounting plate of the high modulus spring, and the water inlet pipeline of the hydraulic pump is placed in the reservoir; the well Ejection module in horizontal section similar to the material in the sample compartment seam side close to the wellhead, a liquid outlet nozzle toward the side of the vertical wells in the sample compartment.

Further, the test device further includes an abrasive tank and a mixing chamber, the outlet of the abrasive tank and the outlet of the impact pressure chamber communicate with the inlet of the mixing chamber, and the outlet of the mixing chamber communicates with the downhole injection module; the outlet of the abrasive tank is provided with a shut-off valve, A branch communicating with the mouth of the abrasive tank is provided on the outlet pipeline of the impact pressure chamber, and a pressure sensor 2 is provided on the branch.

Further, the test device further includes an intermediate container, the inlet of the intermediate container is in communication with the outlet of the constant speed and constant pressure pump, and the outlet of the intermediate container is in communication with the impact pressure chamber.

Further, the water inlet section of the spray head is a cylindrical section, and the water outlet section is a nozzle. The nozzle is a cone that gradually decreases in inner diameter from the water inlet to the water outlet. The element, the spinning element, the nozzle and the cylindrical section are arranged coaxially.

Further, the spinning element is a cylindrical body with a spiral track on the outer circle, and the outer circle matches the inner diameter of the cylindrical section.

An in-situ test method for pressure relief of coal-bed methane horizontal wells in construction coal includes the following steps:

1) Arrange the location of each equipment and connect the equipment;

2) According to the pulse frequency required by the test, set the electromagnetic clutch power-off frequency, constant speed and constant pressure pump water injection frequency, hydraulic cylinder reciprocating motion frequency, the three are consistent; according to the impact strength required by the test, set the displacement sensor displacement, Then control the reciprocating stroke of the hydraulic cylinder and the compression of the high modulus spring;

3) Start the hydraulic pump and the constant speed and constant pressure pump, inject liquid into the hydraulic cylinder and the impact pressure chamber respectively, and at the same time the electromagnetic clutch is energized to work, the hydraulic cylinder drives the guide rod to move to the left to compress the high modulus spring;

4) When the compression of the high modulus spring detected by the displacement sensor reaches the compression length of the test design, the piston rod of the hydraulic cylinder stops moving. After the impact pressure chamber is filled with liquid, the constant speed and constant pressure pump stops injecting the liquid and the electromagnetic clutch is broken. The electric stop working, the guide rod is separated from the hydraulic cylinder, the restoring force of the high modulus spring makes the impact piston move to the right quickly, forming an instant pulse power to the liquid in the impact pressure chamber, and injected into the coal seam of similar material after three-stage acceleration by the downhole injection module In the horizontal well;

5) After the restoring force of the high modulus spring is released, the piston rod of the hydraulic cylinder moves right to contact with the guide rod;

6) According to the parameters set in step 2), repeat steps 3) to 5);

7) After the test, disassemble the pipeline, open the sample compartment, remove the similar materials after the test, the downhole injection module, and clean the inside of the sample compartment.

As a first step, in the above step 2), the opening and closing frequency of the cut-off valve is set to be consistent with the reciprocating frequency of the hydraulic cylinder.

The invention consists of a high-pressure pulsating fluid injection module composed of a hydraulic cylinder, a hydraulic pump, a high modulus spring, an impact pressure chamber and a constant speed constant pressure pump, which solves the laboratory pulsation pump with low flow rate, low impact intensity and low control accuracy, which cannot be satisfied The problem of the test demand realized the experiment of injecting high-pressure and high-speed fluid into the horizontal well cave at a certain pulse frequency, cutting and breaking the coal body, simulating the construction of coal-bed methane horizontal well pressure pulsation excitation and stress release (ie, pressure relief and permeability enhancement). The research and development of cave pressure relief development technology, parameter optimization, feasibility evaluation, and production capacity prediction model establishment have laid the theoretical foundation and provided a platform for indoor testing of development technology equipment.

BRIEF DESCRIPTION

FIG. 1 is a schematic diagram of the test device of the present invention.

Fig. 2 is a schematic view of the structure of a spray head.

In the picture: 1. liquid reservoir, 2. hydraulic pump, 3. pressure sensor 1, 5, hydraulic cylinder, 6, high modulus spring, 7, guide rod, 8, displacement sensor, 9, impact pressure chamber, 10, Impact piston, 11, electromagnetic clutch, 12.1, valve one, 12.2 valve two, 12.3, valve three, 12.4, valve four, 12.5, valve five, 12.6, valve six, 12.7, valve seven, 13, intermediate container, 14, constant Speed constant pressure pump, 15, pressure sensor two, 16, abrasive tank, 17, globe valve, 18, mixing chamber, 19, sample bin, 19.1, coal seam of similar materials, 19.2, horizontal well, 19.3, vertical well, 20, sprinkler, 20.1, cylindrical section, 20.2, spinning element, 20.3, nozzle.

detailed description

The present invention will be further described below with reference to the drawings (the left-right direction in the following description is the same as the left-right direction in FIG. 1).

As shown in FIG. 1, an in-situ coal-bed methane horizontal well pressure relief test device for coal construction includes a high-pressure pulsating fluid injection module and a downhole injection module. The high-pressure pulsating fluid injection module includes a hydraulic pump 2, a hydraulic cylinder 5, and a high Modulus spring 6, impact pressure chamber 9 and constant speed and constant pressure pump 14, the hydraulic pump 2 is hydraulically connected to the hydraulic cylinder 5 through a solenoid valve, and the right end of the guide rod 7 is fixedly connected to the right mounting plate of the high modulus spring 6 The left end passes through the left mounting plate of the high modulus spring 6 and is slidingly connected to it. The piston rod of the hydraulic cylinder 5 and the guide rod 7 are arranged coaxially, and there is an electromagnetic between the end surface of the piston rod of the hydraulic cylinder 5 and the left end surface of the guide rod 7 Clutch 11; the left end of the impact piston 10 in the impact pressure chamber 9 extends out of the impact pressure chamber 9 and is fixedly connected to the right mounting plate of the high modulus spring 6, the cavity in the impact pressure chamber 9 on the right side of the impact piston 10 and the constant speed The outlet of the constant pressure pump 14 is connected with a valve 12.1 on the communication pipeline, the outlet pipeline of the impact pressure chamber 9 is communicated with the downhole injection module, and the valve 4 is 12.4 on the communication pipeline; the outlet pipeline of the hydraulic pump 2 is provided with pressure Sensor one 3, high modulus spring 6 Displacement sensor 8 is provided on the right mounting plate, and the water inlet pipeline of hydraulic pump 2 is placed in liquid storage tank 1; the underground injection module is placed in a similar material coal seam 19.1 in the sample chamber 19 and the horizontal well 19.2 is close to the horizontal section On the side of the wellhead, the liquid outlet of the nozzle 20 faces the side of the vertical well 19.3 in the sample chamber 19.

The test device further includes an abrasive tank 16 and a mixing chamber 18. The outlet of the abrasive tank 16 and the outlet of the impact pressure chamber 9 communicate with the inlet of the mixing chamber 18. The outlet of the mixing chamber 18 communicates with the downhole injection module; Abrasives can increase the ability of liquid to cut coal and rock and improve the efficiency of pressure relief and permeability enhancement; the outlet of the abrasive tank 16 is provided with a shut-off valve 17 for controlling the input of abrasive into the mixing chamber 18; spraying at the outlet of the mixing chamber 18 and downhole The pipeline between the modules is equipped with the main valve for controlling fluid, namely valve six 12.6; the outlet pipe of the impact pressure chamber 9 is provided with a branch communicating with the tank port of the abrasive tank 16 and a pressure sensor two 15 is provided on the branch; The branch line between the pressure chamber 9 and the pressure sensor two 15 is provided with a valve three 12.3, and the line between the pressure sensor two 15 and the abrasive tank 16 is provided with a valve five 12.5; a valve is provided on the top of the abrasive tank 16 Seven 12.7.

The test device further includes an intermediate container 13. The inlet of the intermediate container 13 communicates with the outlet of the constant speed and constant pressure pump 14. A valve 12.2 is provided on the communication pipeline. The outlet of the intermediate container 13 communicates with the impact pressure chamber 9. The liquid flow pressure and flow rate of the constant speed constant pressure pump 14 can be made more stable.

As shown in FIG. 2, the water inlet section of the nozzle 20 is a cylindrical section 20.1, and the water outlet section is a nozzle 20.3. The nozzle 20.3 is a tapered inner diameter gradually decreasing from the water inlet to the water outlet. There is a spinning element 20.2 between the nozzle 20.3, the spinning element 20.2, the nozzle 20.3 and the cylindrical section 20.1 are arranged coaxially; after the fluid enters the nozzle 20, it passes through the spinning element 20.2 and has a three-dimensional velocity, which changes from linear flow to rotation The flow method, after passing through the cone-shaped nozzle 20.3, the speed is increased to a high-speed jet, so that the impact on the coal seam is more powerful and the pressure relief effect is better.

The spinning element 20.2 is a cylindrical body with a spiral track on the outer circle. The outer circle matches the inner diameter of the cylindrical section 20.1, which is convenient for installation in the spray head 20.

1) Arrange the location of each equipment and connect the equipment;

2) According to the pulse frequency required by the test, set the power off frequency of the electromagnetic clutch 11, the water injection frequency of the constant speed and constant pressure pump 14, and the reciprocating frequency of the hydraulic cylinder 5. The three are consistent; according to the impact strength required by the test, set the displacement sensor 8 The amount of displacement, which in turn controls the reciprocating stroke of the hydraulic cylinder 5 and the amount of compression of the high modulus spring 6;

3) Open valve 1 12.1, valve two 12.2, valve three 12.3, valve four 12.4, and valve six 12.6, start hydraulic pump 2 and constant speed and constant pressure pump 14, and inject liquid into hydraulic cylinder 5 and impact pressure chamber 9, respectively, at the same time The electromagnetic clutch 11 is energized to work, and the hydraulic cylinder 5 drives the guide rod 7 to the left to compress the high modulus spring 6 (in this process, the left mounting plate of the high modulus spring 6 is stationary relative to the outer cylinder of the hydraulic cylinder 5);

4) When the compression degree of the high modulus spring 6 detected by the displacement sensor 8 (that is, the displacement of the right mounting plate of the high modulus spring 6) reaches the experimental design compression length, the piston rod of the hydraulic cylinder 5 stops moving, and the pressure chamber 9 is to be impacted After the interior is filled with liquid, the constant speed and constant pressure pump 14 stops injecting liquid, the electromagnetic clutch 11 is powered off and stops working, the guide rod 7 is separated from the hydraulic cylinder 5, and the restoring force of the high modulus spring 6 causes the impact piston 10 to move quickly to the right. The liquid in the pressure chamber 9 forms an instant pulse power, which is injected into the horizontal well of similar material coal seam 19.1 after three-stage acceleration of the downhole injection module;

5) After the restoring force of the high modulus spring 6 is released, the piston rod of the hydraulic cylinder 5 moves right to contact with the guide rod 7;

6) According to the parameters set in step 2), repeat steps 3) to 5), the liquid in the impact pressure chamber 9 will cut and break the similar material coal layer 19.1 at the pulse frequency, pressure and rate of the experimental design, resulting in Space collapse of horizontal section of horizontal well of similar material coal seam forms pressure relief cavern, which is convenient for subsequent coal bed methane exploitation;

7) After the test, disassemble the pipeline, open the sample compartment 19, remove the similar materials after the test, the downhole injection module, and clean the inside of the sample compartment 19.

In step 2), the opening and closing frequency of the cut-off valve 17 is set to be consistent with the reciprocating frequency of the hydraulic cylinder 5. In this way, abrasives can be added to the high-pressure, high-speed liquid to increase the cutting force of the liquid on coal seams of similar materials.

Claims

An in-situ coal-bed methane horizontal well pressure-relief test device for coal construction is characterized by comprising a high-pressure pulsating fluid injection module and a downhole injection module. The high-pressure pulsating fluid injection module includes a hydraulic pump (2) and a hydraulic cylinder (5) , High modulus spring (6), impact pressure chamber (9) and constant speed and constant pressure pump (14), the hydraulic pump (2) is hydraulically connected to the hydraulic cylinder (5), the right end of the guide rod (7) is connected to The right mounting plate of the high modulus spring (6) is fixedly connected, the left end passes through the left mounting plate of the high modulus spring (6) and is slidingly connected thereto, the piston rod of the hydraulic cylinder (5) and the guide rod (7) are arranged coaxially , An electromagnetic clutch (11) is provided between the end surface of the piston rod of the hydraulic cylinder (5) and the left end surface of the guide rod (7); the left end of the impact piston (10) in the impact pressure chamber (9) extends out of the impact pressure chamber (9) It is fixedly connected with the right mounting plate of the high modulus spring (6), the cavity of the impact pressure chamber (9) is connected with the outlet of the constant speed and constant pressure pump (14), and the outlet pipeline of the impact pressure chamber (9) is downhole The injection module is connected; the outlet pipe of the hydraulic pump (2) is provided with a pressure sensor one (3), the right mounting plate of the high modulus spring (6) is provided with a displacement sensor (8), and the water inlet of the hydraulic pump (2) The pipeline is placed in the storage tank (1); the downhole injection module is placed in the horizontal well (19.2) of the similar material coal seam (19.1) in the sample compartment (19) on the side near the wellhead, the nozzle (20 ) To the side of the vertical well (19.3) in the sample compartment (19).
An in-situ coal-bed methane horizontal well pressure relief test device according to claim 1, wherein the test device further comprises an abrasive tank (16) and a mixing chamber (18), and the abrasive tank (16) The outlet and the outlet of the impact pressure chamber (9) communicate with the inlet of the mixing chamber (18), and the outlet of the mixing chamber (18) communicates with the downhole injection module; the outlet of the abrasive tank (16) is provided with a shut-off valve (17) at the impact pressure The outlet pipe of the cavity (9) is provided with a branch communicating with the mouth of the abrasive tank (16), and a pressure sensor two (15) is provided on the branch.
A pressure relief test device for in-situ coal-bed methane horizontal wells with structured coal according to claim 1 or 2, characterized in that the test device further comprises an intermediate container (13), the inlet of the intermediate container (13) and the constant The outlet of the speed constant pressure pump (14) communicates, and the outlet of the intermediate container (13) communicates with the impact pressure chamber (9).
A pressure relief test device for in-situ coal-bed methane horizontal wells according to claim 3, characterized in that: the inner water inlet section of the sprinkler (20) is a cylindrical section (20.1), and the water outlet section is a nozzle (20.3) ), The nozzle (20.3) is a cone that gradually decreases from the water inlet to the water outlet, and a spinning element (20.2) is provided between the cylindrical section (20.1) and the nozzle (20.3). 20.2), the nozzle (20.3) and the cylindrical section (20.1) are arranged coaxially.
A pressure relief test device for in-situ coal-bed methane horizontal wells with structured coal according to claim 4, characterized in that the spinning element (20.2) is a cylindrical body with a spiral track on the outer circle, and the outer circle is The inner diameter of the cylindrical section (20.1) matches.
An in-situ test method for pressure relief of coal-bed methane horizontal wells in construction coal, which is characterized by the following steps:

1) Arrange the location of each equipment and connect the equipment;

2) According to the pulse frequency required by the test, set the electromagnetic clutch (11) power-off frequency, the water injection frequency of the constant speed and constant pressure pump (14), and the reciprocating motion frequency of the hydraulic cylinder (5). Strength, set the displacement of displacement sensor (8), and then control the reciprocating stroke of hydraulic cylinder (5) and the compression of high modulus spring (6);

3) Start the hydraulic pump (2) and the constant speed and constant pressure pump (14), respectively inject liquid into the hydraulic cylinder (5) and the impact pressure chamber (9), and the electromagnetic clutch (11) is energized to work, and the hydraulic cylinder (5) Drive the guide rod (7) to the left to compress the high modulus spring (6);

4) When the compression degree of the high modulus spring (6) detected by the displacement sensor (8) reaches the compression length of the test design, the piston rod of the hydraulic cylinder (5) stops moving, and after the impact pressure chamber (9) is filled with liquid, The constant speed and constant pressure pump (14) stops injecting liquid, the electromagnetic clutch (11) is powered off and stops working, the guide rod (7) is disengaged from the hydraulic cylinder (5), and the restoring force of the high modulus spring (6) makes the impact piston (10) ) Quickly move to the right to form an instantaneous pulse power to the liquid in the impact pressure chamber (9), which is injected into the horizontal well of similar material coal seam (19.1) after three-stage acceleration of the downhole injection module;

5) After the release force of the high modulus spring (6) is released, the piston rod of the hydraulic cylinder (5) moves right to contact with the guide rod (7);

6) According to the parameters set in step 2), repeat steps 3) to 5);

7) After the test, disassemble the pipeline, open the sample compartment (19), remove the similar materials after the test, the downhole injection module, and clean the inside of the sample compartment (19).
An in-situ test method for decompressing coal-bed methane horizontal wells according to claim 6, wherein in step 2), the opening and closing frequency of the shut-off valve (17) and the reciprocation of the hydraulic cylinder (5) are set Movement frequency is consistent.