A coalbed methane multi-layer combined production experimental device

Abstract

The present invention discloses a coalbed methane multi-layer combined production experimental device, which includes: a reservoir simulation system, a wellbore simulation system, and a control and data acquisition system; the reservoir simulation system includes a plurality of parallel coalbed simulation components to simulate the reservoir conditions of multiple coalbeds; the wellbore simulation system includes a cylinder to simulate the wellbore drainage and gas production process; the coalbed simulation components are respectively connected to different heights of the cylinder, so that the wellbore simulation system simulates the output characteristics and pressure differences between the coal layers in the wellbore of the coalbed methane well; the control and data acquisition system is respectively connected to the reservoir simulation system and the wellbore simulation system, and is used to issue control instructions and collect simulation data. The experimental device in the present invention can realize the simulation of the multiphase flow conditions in the wellbore during the combined production of multiple coalbeds. By associating the reservoir simulation with the wellbore simulation, it can not only accurately simulate the real situation of the reservoir, but also simulate the conditions in the wellbore during production research.

Description

Technical Field

[0001] The invention relates to the technical field of coalbed methane mining, and in particular to a coalbed methane multi-layer combined mining experimental device. Background Art

[0002] Among my country's coalbed methane resources, the coalbed methane resources with the characteristics of "coal seam group" development are huge. For multi-layer superimposed coalbed methane systems, multi-layer combined production can not only reduce the investment in a single well and increase the service life of coalbed methane wells, but also improve the recovery rate of coalbed methane. In the process of multi-layer combined production of coalbed methane, the flow pressure of each layer is controlled by changing the height of the dynamic liquid level and the casing pressure to carry out production. The difference in fluid energy between different layers and the impact of gas-liquid two-phase flow on the pressure of each layer will affect the production of the coal seam.

[0003] At present, there are some simulation experimental devices for the flow characteristics in the wellbore during the coalbed methane production process, such as the coal powder production experimental device in the vertical wellbore, the wellbore annulus multiphase flow visualization simulation experimental device, and the drainage gas production experimental device. However, the current simulation of coalbed methane extraction has the following shortcomings: the experimental instruments are mostly used for the simulation of coalbed methane extraction in a single coal seam, and cannot realize the wellbore simulation for the combined extraction of multiple coal seams. Summary of the invention

[0004] In view of the existing technical problems, the present invention proposes a coalbed methane multi-layer combined production experimental device to overcome the above problems.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a coalbed methane multi-layer combined production experimental device, the experimental device comprising: a reservoir simulation system, a wellbore simulation system and a control and data acquisition system;

[0007] The reservoir simulation system includes a plurality of parallel coal seam simulation components to simulate multi-coal seam reservoir conditions;

[0008] The wellbore simulation system includes a cylinder body for simulating the wellbore drainage and gas production process;

[0009] The coal seam simulation components are respectively connected to different heights of the cylinder, so that the wellbore simulation system simulates the production characteristics and pressure differences between the coal seams in the wellbore of the coalbed methane well;

[0010] The control and data acquisition system is connected to the reservoir simulation system and the wellbore simulation system respectively, and is used to issue control instructions and collect simulation data.

[0011] Furthermore, the coal seam simulation component includes: a pressure reducing valve, a first flow relief valve, a first pressure measuring unit, a core clamp, a second pressure measuring unit, a first flow meter, a second flow relief valve and a first check valve connected in sequence, as well as a core arranged in the core clamp and a confining pressure loading unit arranged on the core clamp; the pressure reducing valve is connected to the gas source, the first check valve is connected to the cylinder, and the first pressure measuring unit, the second pressure measuring unit, the first flow meter and the confining pressure loading unit are connected to the control and data acquisition system.

[0012] Furthermore, the reservoir simulation system further comprises: a vacuum pump;

[0013] The vacuum pump is connected to the gas input end of the coal seam simulation component via a third leakage valve.

[0014] Furthermore, the wellbore simulation system further comprises: a water tank and a water pump, wherein the water pump is arranged in the water tank;

[0015] The water pump is connected to the upper end of the cylinder through the second flow meter, the fourth flow relief valve and the second one-way valve in sequence; the water tank is connected to the lower end of the cylinder through the third flow meter and the fifth flow relief valve in sequence; or, the water pump is connected to the cylinder through the second flow meter, the fourth flow relief valve and the second one-way valve in sequence, and the second one-way valve is connected to the bottom of the cylinder through a pipeline;

[0016] The second flow meter and the third flow meter are connected to the control and data acquisition system.

[0017] Furthermore, an exhaust pipeline is provided at the upper end of the cylinder, a back pressure valve and a fourth flow meter are provided on the exhaust pipeline, and the fourth flow meter is connected to the control and data acquisition system.

[0018] Furthermore, at the height connected to each of the coal seam simulation components, the cylinder is provided with a third pressure measuring unit, and the third pressure measuring unit is connected to the control and data acquisition system.

[0019] Furthermore, the cylinder body comprises a plurality of sections of transparent pressure-resistant glass tubes, and an external pipe line connected to the cylinder body is provided at the joint of two adjacent sections of transparent pressure-resistant glass tubes, and the coal seam simulation component and the third pressure measuring unit are connected to the cylinder body through the external pipe line.

[0020] Furthermore, a first sealing ring is provided between two adjacent sections of the transparent pressure-resistant glass tube; a second sealing ring is provided between the transparent pressure-resistant glass tube and the external pipe line; and a stop valve is provided on the external pipe line.

[0021] Furthermore, the cross-section of the cylinder is circular, elliptical, square, rectangular or diamond-shaped.

[0022] Furthermore, the wellbore simulation system also includes: a barrel rotating device, which can fix the barrel vertically or tilted at any angle.

[0023] In summary, the beneficial effects of the present invention are:

[0024] The coalbed methane multi-layer combined production experimental device in the present invention can simulate the multiphase flow conditions in the wellbore during the combined production of multiple coal seams. By associating reservoir simulation with wellbore simulation, it can not only accurately simulate the actual situation of the reservoir, but also simulate the conditions in the wellbore during production research; the coalbed methane multi-layer combined production experimental device can simulate the differences in depth and energy storage energy of each layer, simulate the output characteristics between each layer and the difference in pressure of each layer in the wellbore, which is more in line with the actual production conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram of a coalbed methane multi-layer combined production experimental device provided by an embodiment of the present invention;

[0026] Figure 2 A diagram of a connection structure of adjacent transparent pressure-resistant glass tubes is provided for one embodiment of the present invention.

[0027] In the figure: 1, the sixth relief valve, 2, the gas source, 3, the third relief valve, 4, the vacuum pump, 5, the pressure reducing valve, 6, the first relief valve, 7, the first pressure measuring unit, 8, the confining pressure loading unit, 9, the core holder, 10, the second pressure measuring unit, 11, the first flow meter, 12, the second relief valve, 13, the first check valve, 14, the fourth flow meter, 15, the back pressure valve, 16, the second check valve, 17, the fourth relief valve, 18, the second flow meter, 19, the water tank, 20, the water pump, 21, the third flow meter, 22, the fifth relief valve, 23, the third pressure measuring unit, 24, the cylinder, 25, the transparent pressure-resistant glass tube, 26, the external pipeline, 27, the first sealing ring, 28, the second sealing ring, 29, the stop valve, 30, the bolt group, I, the control and data acquisition system, II, the reservoir simulation system, III, the wellbore simulation system. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] One embodiment of the present invention discloses a coalbed methane multi-layer combined production experimental device, such as Figure 1 As shown, the experimental device includes: a reservoir simulation system II, a wellbore simulation system III and a control and data acquisition system I.

[0032] The reservoir simulation system II includes several parallel coal seam simulation components, which simulate multi-coal seam reservoir conditions by connecting multiple pipelines in parallel. The number of parallel coal seam simulation components can be adjusted according to simulation needs.

[0033] The wellbore simulation system III includes a cylinder 24 for simulating the wellbore drainage and gas production process.

[0034] The coal seam simulation components are connected to different heights of the cylinder 24, respectively, so that the wellbore simulation system III simulates the production characteristics and pressure differences between the coal seams in the wellbore of the coalbed methane well.

[0035] The control and data acquisition system I is connected to the reservoir simulation system II and the wellbore simulation system III respectively, and is used to issue control instructions and collect simulation data.

[0036] The coalbed methane multi-layer combined production experimental device in the present invention can simulate the multiphase flow conditions in the wellbore during the combined production of multiple coal seams. By associating the reservoir simulation with the wellbore simulation, it can not only accurately simulate the actual situation of the reservoir, but also simulate the conditions in the wellbore during production research. Since the coalbed methane multi-layer combined production experimental device has multiple coal seam simulation components connected to different heights of the cylinder 24, it can simulate the differences in depth and energy storage energy of each layer.

[0037] In one embodiment, the coal seam simulation component includes: a pressure reducing valve 5, a first relief valve 6, a first pressure measuring unit 7, a core holder 9, a second pressure measuring unit 10, a first flow meter 11, a second relief valve 12 and a first check valve 13 connected in sequence, and a core arranged in the core holder 9 and a confining pressure loading unit 8 arranged on the core holder 9; the pressure reducing valve 5 is connected to the gas source 2, and the first check valve 13 is connected to the cylinder 24. The first pressure measuring unit 7, the second pressure measuring unit 10, the first flow meter 11 and the confining pressure loading unit 8 are connected to the control and data acquisition system I to realize data acquisition and management.

[0038] In this embodiment, the gas source 2 can be a number of high-pressure gas cylinders. According to the actual production situation, the gas provided by the gas source 2 can be nitrogen and carbon dioxide, etc., wherein the switch of each gas cylinder is controlled by the sixth relief valve 1. The core is placed in the core holder 9 to simulate the formation, and the stress condition of the reservoir is simulated by the confining pressure loading unit 8, and the multi-coal seam reservoir conditions are simulated by connecting multiple coal seam simulation components in parallel. On each coal seam simulation component, the energy of each reservoir gas is controlled by the pressure reducing valve 5, the first relief valve 6 and the second relief valve 12 control the switch of the pipeline at both ends of the core holder 9, the first pressure measuring unit 7 and the second pressure measuring unit 10 are used to measure the pressure at both ends of the core holder 9, the first flowmeter 11 is used to measure the flow of gas passing through the coal seam simulation component, and the first one-way valve 13 is used to prevent the liquid in the cylinder 24 from entering the coal seam simulation component. The physical parameters (permeability, porosity and stress conditions) of artificial formations in actual production can be achieved by core production and applying axial pressure and confining pressure to the core, thereby simulating the real formation; and the energy of each reservoir can be achieved by adjusting the pressure of the pressure reducing valve 5 in each coal seam simulation component to obtain the required pressure to meet the characteristics of simulating the energy differences of different reservoirs.

[0039] In one embodiment, the reservoir simulation system II further includes: a vacuum pump 4 .

[0040] from Figure 1 As can be seen in FIG. 1 , the vacuum pump 4 is connected to the gas input end of the coal seam simulation component via the third relief valve 3. The vacuum pump 4 is used to evacuate the core in the core holder 9 and provide axial pressure.

[0041] In one embodiment, Figure 1 As shown, the wellbore simulation system III also includes: a water tank 19 and a water pump 20 , and the water pump 20 is arranged in the water tank 19 .

[0042] exist Figure 1In the illustrated embodiment, the water pump 20 is connected to the upper end of the cylinder 24 through the second flow meter 18, the fourth relief valve 17 and the second one-way valve 16 in sequence, and the water pump 20 can pump the water in the water tank 19 into the cylinder 24 to simulate formation water. The second flow meter 18 is used to measure the amount of pumped water, the fourth relief valve 17 is used to control the switch of the pumping pipeline, and the second one-way valve 16 can prevent the gas in the cylinder 24 from entering the pumping pipeline; the water tank 19 is connected to the lower end of the cylinder 24 through the third flow meter 21 and the fifth relief valve 22 in sequence, and is used to put the water in the cylinder 24 into the water tank 19. The third flow meter 21 is used to measure the amount of water discharged, and the fifth relief valve 22 is used to control the switch of the discharge pipeline.

[0043] Alternatively, in other embodiments of the present application, the water pump 20 is connected to the cylinder 24 through the second flow meter 18, the fourth drain valve 17, and the second one-way valve 16 in sequence, and the second one-way valve 16 is connected to the bottom of the cylinder 24 through a pipeline. Due to the design that the second one-way valve 16 is connected to the bottom of the cylinder 24 through a pipeline, the drain pipeline can be omitted and the lower end of the cylinder 24 can be simply sealed.

[0044] The second flow meter 18 and the third flow meter 21 are connected to the control and data acquisition system 1 to realize data acquisition and management. In addition, the water pump 20 is also connected to the control and data acquisition system 1 to receive opening, closing and power control.

[0045] exist Figure 1 In the illustrated embodiment, an exhaust pipeline is provided at the upper end of the cylinder 24, and a back pressure valve 15 and a fourth flow meter 14 are provided on the exhaust pipeline. The fourth flow meter 14 is used to measure the gas flow rate discharged during simulated production, and the fourth flow meter 14 is connected to the control and data acquisition system I.

[0046] In the wellbore simulation system III, a back pressure valve 15 is used to control the casing pressure in the cylinder 24, and the height of the liquid level in the cylinder 24 is controlled by a water pump 20 and a fifth relief valve 22, thereby simulating the actual conditions in the wellbore during production.

[0047] exist Figure 1 In the illustrated embodiment, at the height where each coal seam simulation component is connected, the cylinder 24 is provided with a third pressure measuring unit 23, and the third pressure measuring unit 23 is connected to the control and data acquisition system I to realize detection and control of the third pressure measuring unit 23. By arranging the third pressure measuring unit 23 at different heights of the cylinder 24, the pressure of each section in the cylinder 24 can be detected in real time.

[0048] In one embodiment, Figure 2As shown, the cylinder 24 includes several sections of transparent pressure-resistant glass tubes 25, and an external pipe 26 connected to the cylinder 24 is provided at the joint of two adjacent sections of transparent pressure-resistant glass tubes 25. The coal seam simulation component and the third pressure measuring unit 23 are connected to the cylinder 24 through the external pipe 26. The cylinder 24 adopts a multi-section transparent pressure-resistant glass tube 25, which is convenient for setting sensors and pipelines between each section of the transparent pressure-resistant glass tube 25, and the gas-liquid two-phase flow in the cylinder 24 can be directly observed, and the visualization effect is good. In order to facilitate the control of the height between each simulated reservoir during the experiment, each transparent pressure-resistant glass tube 25 can be set to an uneven length.

[0049] In one embodiment, Figure 2 As shown, a first sealing ring 27 is provided between two adjacent transparent pressure-resistant glass tubes 25; a second sealing ring 28 is provided between the transparent pressure-resistant glass tube 25 and the external pipe 26; and a stop valve 29 is provided on the external pipe 26. The two adjacent transparent pressure-resistant glass tubes 25 are connected and fixed by multiple groups of bolt groups 30, and the sealing performance is improved by providing the first sealing ring 27, and the stop valve 29 can be used to control the on and off of the external pipe 26.

[0050] In one embodiment, the cross section of the cylinder 24 is circular, oval, square, rectangular or diamond-shaped. Of course, the cross section of the cylinder 24 is not limited to the above shapes, and the specific shape can be adjusted as needed.

[0051] In one embodiment, the wellbore simulation system III further includes: a barrel rotating device, which can fix the barrel 24 vertically or tilted at any angle. The barrel rotating device can fix the barrel 24 on the one hand, and can set the barrel 24 vertically or tilted as needed on the other hand, so that the tilt angle can be adjusted arbitrarily, which is convenient for simulating wellbores in various situations.

[0052] The pressure measuring unit in the present invention may be a pressure sensor or a pressure gauge, and the flow meter in the present invention may be replaced by a mass flow sensor, which is also within the protection scope of the present invention.

[0053] The use steps of the coalbed methane multi-layer combined production experimental device of the present invention are as follows:

[0054] Step 1: Make a core, put the coal rock into the core holder 9, and check the air tightness of the whole device;

[0055] Step 2: Open the third relief valve 3 and the first relief valve 6, close the sixth relief valve 1 and the second relief valve 12, and use the vacuum pump 4 to evacuate the core;

[0056] Step 3: According to the demand, different confining pressures are applied to each core layer through the confining pressure loading unit 8, the third relief valve 3 is closed, the sixth relief valve 1, the first relief valve 6 and the second relief valve 12 are opened, and CH4 is injected into the core at a certain pressure so that the coal rock can fully absorb CH4;

[0057] Step 4: close the second drain valve 12, turn on the water pump 20, and make the liquid level in the cylinder 24 reach a specified height;

[0058] Step 5: Adjust the pressure of the pressure reducing valve 5 so that the coal seam simulation component reaches the required reservoir energy of each layer, and open the second relief valve 12 at the same time;

[0059] Step 6: Control the pressure in each coal seam simulation component by adjusting the pressure of the back pressure valve 15 and the height of the liquid level in the cylinder 24, and control the height of the liquid level in the cylinder 24 by the fifth relief valve 22 and the water pump 20;

[0060] Step 7: During the experiment, collect the flow rate and pressure at each location and their changes.

[0061] In summary, the coalbed methane multi-layer combined production experimental device in the present invention can simulate the multiphase flow conditions in the wellbore during the combined production of multiple coal seams. By associating the reservoir simulation with the wellbore simulation, it can not only accurately simulate the real situation of the reservoir, but also simulate the conditions in the wellbore during production. In the present application, the cylinder 24 is used to simulate the drainage and gas production process of the wellbore. By adjusting the dynamic liquid level height and the casing pressure in the cylinder 24 in the wellbore simulation system III, the output characteristics between the layers and the pressure differences between the layers in the wellbore can be easily simulated, which is more in line with the actual production conditions. The experimental device of the present application can simulate the differences and changes in the gas production of each coal seam during the multi-layer combined production of coalbed methane, and then study the interference mechanism between the layers during the multi-layer combined production, which is conducive to the formulation of a reasonable drainage and production system in actual production; the design of the control and data acquisition system enables the experimental device to have a wealth of data acquisition channels, and the overall degree of automation of the device is high, and real-time data can be directly collected for research. The experimental device in the present invention is not only limited to experimental simulations of coalbed methane combined production in multiple coal seams, but can also be used for experimental simulations of sandstone gas and shale gas combined production.

[0062] The above is only a specific embodiment of the present invention. Under the above teachings of the present invention, those skilled in the art can make other improvements or modifications on the basis of the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of the present invention, and the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A coalbed methane multi-layer combined production experimental device, characterized in that: The experimental device includes: a reservoir simulation system, a wellbore simulation system, and a control and data acquisition system; The reservoir simulation system includes a plurality of parallel coal seam simulation components to simulate multi-coal seam reservoir conditions; The wellbore simulation system includes a cylinder body for simulating the wellbore drainage and gas production process; The coal seam simulation components are respectively connected to different heights of the cylinder, so that the wellbore simulation system simulates the production characteristics and pressure differences between the coal seams in the wellbore of the coalbed methane well; The control and data acquisition system is connected to the reservoir simulation system and the wellbore simulation system respectively, and is used to issue control instructions and collect simulation data; The coal seam simulation component comprises: a pressure reducing valve, a first flow relief valve, a first pressure measuring unit, a core holder, a second pressure measuring unit, a first flow meter, a second flow relief valve and a first check valve connected in sequence, as well as a core arranged in the core holder and a confining pressure loading unit arranged on the core holder; the pressure reducing valve is connected to a gas source, the first check valve is connected to the cylinder, and the first pressure measuring unit, the second pressure measuring unit, the first flow meter and the confining pressure loading unit are connected to the control and data acquisition system; The wellbore simulation system further comprises: a water tank and a water pump, wherein the water pump is arranged in the water tank; The water pump is connected to the upper end of the cylinder through the second flow meter, the fourth flow relief valve and the second one-way valve in sequence; the water tank is connected to the lower end of the cylinder through the third flow meter and the fifth flow relief valve in sequence; or, the water pump is connected to the cylinder through the second flow meter, the fourth flow relief valve and the second one-way valve in sequence, and the second one-way valve is connected to the bottom of the cylinder through a pipeline; The second flow meter and the third flow meter are connected to the control and data acquisition system; At the height connected to each of the coal seam simulation components, the cylinder is provided with a third pressure measuring unit, and the third pressure measuring unit is connected to the control and data acquisition system; The cylinder body comprises a plurality of sections of transparent pressure-resistant glass tubes, and an external pipe line connected to the cylinder body is provided at the joint of two adjacent sections of transparent pressure-resistant glass tubes, and the coal seam simulation component and the third pressure measuring unit are connected to the cylinder body through the external pipe line; The wellbore simulation system further comprises: a barrel rotating device, which can fix the barrel vertically or tilted at any angle.

2. The coalbed methane multi-layer combined production experimental device according to claim 1 is characterized in that: The reservoir simulation system further includes: a vacuum pump; The vacuum pump is connected to the gas input end of the coal seam simulation component via a third leakage valve.

3. The coalbed methane multi-layer combined production experimental device according to claim 1 is characterized in that: An exhaust pipeline is provided at the upper end of the cylinder, a back pressure valve and a fourth flow meter are provided on the exhaust pipeline, and the fourth flow meter is connected to the control and data acquisition system.

4. The coalbed methane multi-layer combined production experimental device according to claim 1 is characterized in that: A first sealing ring is arranged between two adjacent sections of the transparent pressure-resistant glass tube; a second sealing ring is arranged between the transparent pressure-resistant glass tube and the external pipe line; and a stop valve is arranged on the external pipe line.

5. The coalbed methane multi-layer combined production experimental device according to any one of claims 1 to 4, characterized in that: The cross section of the cylinder is circular, elliptical, square, rectangular or rhombus.

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