A system and method for exploiting water-soluble gas

Abstract

A system for exploiting water-soluble gas includes a natural gas source, a pressure regulating device, a production well, a gas-water separator, a filter and a water injection well. The gas-water separator is provided with an inlet, an outlet and a drain. The production well and the water injection well extend from the surface to the water-soluble gas well exploitation (reservoir) layer and the water injection layer, respectively. The production well includes a casing and an oil pipe, and the casing is sealed outside the oil pipe. The natural gas source is connected to the pressure regulating device through a transmission pipeline, and the pressure regulating device is connected to the upper end of the casing through a transmission pipeline. The upper end of the oil pipe is transported to the outside through a transmission pipeline. The main exploitation equipment of the present invention is all placed on the ground. Compared with underground exploitation equipment, it is easy to maintain and has a low investment cost. It mainly adopts self-produced natural gas injection circulation, which has the same composition as the exploited natural gas, is convenient for gas recovery and reuse, and solves the mixing of other components and unnecessary separation steps and waste caused by gas lift exploitation of other media such as nitrogen.

Description

Technical Field

[0001] The invention belongs to the technical field of water-soluble gas exploitation, and in particular relates to a system and method for exploiting water-soluble gas. Background Art

[0002] Water-soluble gas refers to gas dissolved in formation water with methane (generally more than 90%) as the main component, which is a kind of unconventional natural gas. Water-soluble gas is an important component of oil and gas resources. Water-soluble gas resources are abundant all over the world and are distributed in major oil and gas basins on five continents. The world's water-soluble natural gas resources are tens to hundreds of times higher than the total reserves of conventional natural gas. Many famous oil and gas basins also have rich water-soluble natural gas resources.

[0003] The distribution area of ​​water-soluble gas resources in my country is also very wide, and many basins also have water-soluble gas resources, with considerable scale. At present, some basins have begun to explore the exploration and development of water-soluble gas, but the progress is relatively slow. Among them, my country's Qaidam Basin has carried out pilot research on water-soluble gas exploration and trial production, which proves that water-soluble gas development has certain economic benefits.

[0004] Since the 1960s, oil and gas exploration in the Weihe Basin has not made any breakthroughs, but in the later geothermal development process, geothermal water-soluble natural gas with promising prospects was discovered. Since 2010, through the exploration, trial production, production, development process research and resource evaluation of the southern fault terrace of the Gushi Depression, some exciting breakthroughs have finally been achieved, proving that the geothermal water-soluble gas in this area has good development prospects. Among them, the development process directly affects the economic and future prospects of water-soluble gas development. Especially in densely populated cities, due to site restrictions and safety and environmental protection requirements, conventional mining processes are almost impossible to carry out. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a system and method for exploiting water-soluble gas.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] A system for exploiting water-soluble gas comprises a natural gas source, a pressure regulating device, a production well, a gas-water separator, a filter and a water injection well, wherein the gas-water separator is provided with an inlet, an air outlet and a drain outlet, the production well and the water injection well extend from the surface to the water-soluble gas well exploitation (reservoir) layer and the water injection layer respectively, the production well comprises a casing and an oil pipe, the casing is sealed outside the oil pipe, the natural gas source is connected to the pressure regulating device through a delivery pipeline, the pressure regulating device is connected to the upper end of the casing through a delivery pipeline, the upper end of the oil pipe is externally transported through a delivery pipeline, the upper end of the oil pipe is connected to the inlet of the gas-water separator through another delivery pipeline, the drain outlet of the gas-water separator is connected to the upper end of the water injection well through a delivery pipeline, the gas outlet of the gas-water separator is connected to the filter through a delivery pipeline, the filter is connected to the pressure regulating device through a delivery pipeline, valves are provided on the delivery pipeline, and the pressure regulating device is used to adjust the gas pressure sent from the delivery pipeline to drive the liquid in the water-soluble gas reservoir to flow to the upper end of the oil pipe.

[0008] Preferably, the filter is a natural gas filter.

[0009] Preferably, the natural gas source is a city natural gas pipeline, and the natural gas pressure of the city natural gas pipeline is 0.3Mpa.

[0010] Preferably, the pressure regulating device includes a first-stage booster pump, a second-stage booster pump, a buffer tank, a pressure detecting device, a secondary booster pump and a controller; the city natural gas pipeline is connected to the first-stage booster pump through a delivery pipeline; the first-stage booster pump boosts the pressure of the natural gas delivered from the city natural gas pipeline from 0.3Mpa to 2Mpa; the filter is connected to the pressure detecting device through a delivery pipeline; the pressure detecting device is connected to the second-stage booster pump through a delivery pipeline; the second-stage booster pump boosts the pressure of the natural gas delivered from the filter to 2Mpa; the pressure detecting device is connected to the buffer tank through another delivery pipeline; a first solenoid valve is provided on the delivery pipeline connecting the pressure detecting device to the second-stage booster pump; a second solenoid valve is provided on the delivery pipeline connecting the pressure detecting device to the buffer tank; and the pressure detecting device and The controller signal connection is used to send a signal to the controller, and the controller is connected to the first solenoid valve and the second solenoid valve signals to identify the pressure value of the pressure detection device and compare it with the preset value stored therein. The preset value stored in the controller is 2Mpa. When the pressure detection device detects that the pressure of the natural gas delivered from the filter is ≥2Mpa, the controller controls the second solenoid valve to open and controls the first solenoid valve to close. When the pressure detection device detects that the pressure of the natural gas delivered from the filter is <2Mpa, the controller controls the first solenoid valve to open and controls the second solenoid valve to close. The first-stage booster pump and the second-stage booster pump are connected to the buffer tank through a delivery pipeline, and the buffer tank is connected to the secondary booster pump through a delivery pipeline. The secondary booster pump is connected to the upper end of the casing through a delivery pipeline, and the secondary booster pump boosts the pressure of the natural gas delivered from the buffer tank to 7-15Mpa.

[0011] Preferably, the natural gas source is a CNG tank truck, and the rated pressure of the natural gas in the CNG tank truck is 20 MPa.

[0012] Preferably, the pressure regulating device is a pressure regulating skid, which can be used to adjust the pressure of the natural gas delivered by the CNG tank truck from 20Mpa to 7-15Mpa.

[0013] Preferably, a water mixer is provided at the lower end of the casing and the oil pipe to facilitate mixing of gas and water underground.

[0014] Preferably, a branch delivery pipeline is connected to the drainage outlet of the gas-water separator and the delivery pipeline of the water injection well, and the branch delivery pipeline can be connected to the city heating pipeline.

[0015] Preferably, the transmission pipeline for external transmission at the upper end of the oil pipe is connected to a gas transmission pipeline for direct external transmission to users.

[0016] Preferably, the transmission pipeline for external transmission at the upper end of the oil pipe is connected to a gas generator set, and the natural gas is transmitted to users after power generation in the gas generator set.

[0017] Beneficial effects of the present invention

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The mining equipment of the present invention is all placed on the ground. Compared with underground mining equipment, it is easy to maintain and has a low investment cost. It mainly uses self-produced natural gas to inject into the well, which has the same composition as the natural gas being mined, so it is easy to recover and reuse the gas, and solves the mixing of other components and unnecessary separation steps, waste and loss caused by gas lift mining such as nitrogen and other media. The system design follows the Bernoulli equation (p+ρgh+1 / 2ρv2=c) and the principle of conservation of fluid energy, and uses the "energy" carried by the gas and liquid produced in the well to replenish the "energy" through system design, multi-stage pressurization, gas-water separation, filtration, and program control. The closed cycle realizes efficient, integrated and multifunctional drainage gas production, and is suitable for different application scenarios (different depths, temperatures, pressures, gas-water ratios, cluster, horizontal, vertical well types, well site environments, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the terms "upper / lower end", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting / sleeving", "sleeve connection", "connection", etc. should be understood in a broad sense. For example, "connection" 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 those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] See also Figure 1 The present invention provides a technical solution: a system for exploiting water-soluble gas, comprising a natural gas source, a pressure regulating device, a production well, a gas-water separator 4, a filter 5 and a water injection well 6, wherein the gas-water separator 4 is provided with an inlet, a gas outlet and a drain outlet, the production well and the water injection well 6 extend from the surface to the water-soluble gas well exploitation (reservoir) layer and the water injection layer respectively, the production well comprises a casing 31 and an oil pipe 32, the casing 31 is sealed outside the oil pipe 32, the natural gas source is connected to the pressure regulating device through a transmission pipeline, and the pressure regulating device is connected to the casing 31 through a transmission pipeline The upper end of the oil pipe 32 is transported externally through a delivery pipeline, the upper end of the oil pipe 32 is connected to the inlet of the gas-water separator through another delivery pipeline, the drain outlet of the gas-water separator 4 is connected to the upper end of the water injection well 6 through a delivery pipeline, the gas outlet of the gas-water separator 4 is connected to the filter 5 through a delivery pipeline, the filter 5 is connected to the pressure regulating device through a delivery pipeline, and valves are provided on the delivery pipeline. The pressure regulating device is used to adjust the gas pressure sent from the delivery pipeline to be able to drive the liquid in the water-soluble gas reservoir to flow to the upper end of the oil pipe 32.

[0025] During use, when the amount of water-soluble gas (pressure) in the production well is insufficient and the water cannot be lifted to the surface, high-pressure natural gas is injected into the casing 31 through an external natural gas source and a pressure regulating device to increase the bottom hole pressure, so that the water-soluble gas is lifted by the natural gas and rises to the surface through the oil pipe 32. After the water and natural gas are separated by the gas-water separator 4, the water is re-injected into the water reservoir of the re-injection well, and the natural gas is filtered by the filter 5 and then pressure-regulated by the pressure regulating device and injected into the casing 31 to participate in the water-soluble gas extraction work. When the natural gas extracted from the production well can maintain the operation of the system for extracting water-soluble gas, the external natural gas source can be stopped to save costs. When the production well can spray by itself, the system for extracting water-soluble gas is stopped.

[0026] The mining equipment of the present invention is all placed on the ground. Compared with underground mining equipment, it is easy to maintain and has a low investment cost. It mainly uses self-produced natural gas to inject into the well, which has the same composition as the natural gas being mined, making it easy to recover and reuse the gas, and solves the problem of mixing of other components and unnecessary separation steps, waste and loss caused by gas lift mining with other media such as nitrogen.

[0027] Specifically, the filter 5 is a natural gas filter, so as to filter solid particles mixed in the natural gas to avoid damage to the pressure regulating device.

[0028] Specifically, the natural gas source is a city natural gas pipeline 11, and the natural gas pressure of the city natural gas pipeline 11 is 0.3Mpa.

[0029] Specifically, the pressure regulating device includes a first-stage booster pump 21, a second-stage booster pump 22, a buffer tank 23, a pressure detecting device 24, a secondary booster pump 25 and a controller. The city natural gas pipeline 11 is connected to the first-stage booster pump 21 through a delivery pipeline. The first-stage booster pump 21 boosts the pressure of the natural gas delivered from the city natural gas pipeline 11 from 0.3Mpa to 2Mpa. The filter 5 is connected to the pressure detecting device 24 through a delivery pipeline. The pressure detecting device 24 is connected to the second-stage booster pump 22 through a delivery pipeline. The second-stage booster pump 22 boosts the pressure of the natural gas delivered from the filter 5 to 2Mpa. The pressure detecting device 24 is connected to the buffer tank 23 through another delivery pipeline. A first solenoid valve 26 is provided on the delivery pipeline connecting the pressure detecting device 24 and the second-stage booster pump 22. A second solenoid valve 27 is provided on the delivery pipeline connecting the pressure detecting device 24 and the buffer tank 23. The device 24 is connected to the controller signal for sending a signal to the controller. The controller is connected to the first solenoid valve 26 and the second solenoid valve 27 for identifying the pressure value of the pressure detection device 24 and comparing it with the preset value stored therein. The preset value stored in the controller is 2Mpa. When the pressure detection device 24 detects that the pressure of the natural gas delivered by the filter 5 is ≥2Mpa, the controller controls the second solenoid valve 27 to open and controls the first solenoid valve 26 to close. When the pressure detection device 24 detects that the pressure of the natural gas delivered by the filter 5 is <2Mpa, the controller controls the first solenoid valve 26 to open and controls the second solenoid valve 27 to close. The first-stage booster pump 21 and the second-stage booster pump 22 are connected to the buffer tank 23 through a delivery pipeline. The buffer tank 23 is connected to the secondary booster pump 25 through a delivery pipeline. The secondary booster pump 25 is connected to the upper end of the casing 31 through a delivery pipeline. The secondary booster pump 25 boosts the pressure of the natural gas delivered by the buffer tank 23 to 7-15Mpa.

[0030] When in use, the natural gas delivered from the natural gas source is pressurized to 2Mpa by the first stage booster pump 21 and then stored in the buffer tank 23. The natural gas extracted from the production well is filtered by the filter 5, and then the pressure is detected by the pressure detection device 24 and the pressure value is sent to the controller. Specifically, the pressure detection device 24 can use an electronic pressure gauge. The controller identifies the pressure value of the pressure detection device 24 and compares it with the preset value (2Mpa) stored therein. When the pressure detection device 24 detects that the pressure of the natural gas delivered from the filter 5 is ≥2Mpa, the controller controls the second solenoid valve 27 to open and controls the first solenoid valve 27 to open. When the valve 26 is closed, the natural gas is directly delivered to the buffer tank 23. When the pressure detection device 24 detects that the pressure of the natural gas delivered by the filter 5 is less than 2Mpa, the controller controls the first solenoid valve 26 to open and controls the second solenoid valve 27 to close. The natural gas is pressurized to 2Mpa by the second-stage booster pump 22 and then stored in the buffer tank 23. The natural gas is then pressurized to 7-15Mpa by the secondary booster pump 25 and can be injected into the production well. Specifically, the pressure value of the natural gas pressurized by the secondary booster pump 25 can be adjusted according to the downhole pressure of the production well. By setting the buffer tank 23, the pressure regulating device can be guaranteed to work smoothly.

[0031] Furthermore, the natural gas source adopts a CNG tank truck 12, and the rated pressure of the natural gas of the CNG tank truck 12 is 20Mpa. When the distance from the city natural gas pipeline 11 is far or it is inconvenient to connect to the city natural gas pipeline 11, the CNG tank truck 12 is more convenient.

[0032] Furthermore, the pressure regulating device is a pressure regulating skid 28, and the pressure regulating skid 28 can be used to adjust the pressure of the natural gas delivered by the CNG tank truck 12 from 20 MPa to 7-15 MPa.

[0033] Furthermore, a water mixer is provided at the lower end of the casing 31 and the oil pipe 32 to fully mix the natural gas and water, thereby avoiding slug flow in the pipeline and ensuring smooth operation of the system.

[0034] Furthermore, a branch delivery pipeline is connected to the drainage outlet of the gas-water separator 4 and the delivery pipeline of the water injection well 6. The branch delivery pipeline can be connected to the city heating pipeline 7. In winter, the extracted geothermal water can be transported to the city heating pipeline 7 for heating (after heat exchange), thereby effectively utilizing the heat in the geothermal water.

[0035] Furthermore, the transmission pipeline for external transmission at the upper end of the oil pipe 32 is connected to a gas transmission pipeline for direct external transmission to users.

[0036] Furthermore, the transmission pipeline for external transmission at the upper end of the oil pipe 32 is connected to a gas generator set, and the natural gas is transmitted to users after power generation in the gas generator set.

[0037] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by ... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, parameter revisions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for exploiting water-soluble gas, characterized in that: The invention comprises a natural gas source, a pressure regulating device, a production well, a gas-water separator (4), a filter (5) and a water injection well (6), wherein the gas-water separator (4) is provided with an inlet, a gas outlet and a water outlet, the production well and the water injection well (6) extend from the surface to a water-soluble gas well production (reservoir) layer and a water injection layer respectively, the production well comprises a casing (31) and an oil pipe (32), the casing (31) is sealed outside the oil pipe (32), the natural gas source is connected to the pressure regulating device via a transmission pipeline, the pressure regulating device is connected to the upper end of the casing (31) via a transmission pipeline, and the oil pipe (32) The upper end is transported outward through a delivery pipeline, the upper end of the oil pipe (32) is connected to the inlet of the gas-water separator through another delivery pipeline, the drainage outlet of the gas-water separator (4) is connected to the upper end of the water injection well (6) through a delivery pipeline, the gas outlet of the gas-water separator (4) is connected to the filter (5) through a delivery pipeline, and the filter (5) is connected to the pressure regulating device through a delivery pipeline. The delivery pipelines are all provided with valves, and the pressure regulating device is used to adjust the gas pressure sent from the delivery pipeline to a pressure that can drive the liquid in the water-soluble gas reservoir to flow toward the upper end of the oil pipe (32).

2. A system for exploiting water-soluble gas according to claim 1, characterized in that: The filter (5) is a natural gas filter.

3. A system for exploiting water-soluble gas according to claim 1, characterized in that: The natural gas source is a city natural gas pipeline (11), and the natural gas pressure of the city natural gas pipeline (11) is 0.3 MPa.

4. A system for exploiting water-soluble gas according to claim 3, characterized in that: The pressure regulating device comprises a first-stage booster pump (21), a second-stage booster pump (22), a buffer tank (23), a pressure detection device (24), a second-stage booster pump (25) and a controller; the city natural gas pipeline (11) is connected to the first-stage booster pump (21) via a delivery pipeline; the first-stage booster pump (21) increases the pressure of the natural gas delivered by the city natural gas pipeline (11) from 0.3 MPa to 2 MPa; the filter (5) is connected to the pressure detection device (24) via a delivery pipeline; the pressure detection device (24) ) is connected to a second-stage booster pump (22) through a delivery pipeline, the second-stage booster pump (22) boosts the pressure of the natural gas delivered from the filter (5) to 2 MPa, the pressure detection device (24) is connected to the buffer tank (23) through another delivery pipeline, a first solenoid valve (26) is provided on the delivery pipeline connecting the pressure detection device (24) and the second-stage booster pump (22), and a second solenoid valve (27) is provided on the delivery pipeline connecting the pressure detection device (24) and the buffer tank (23), respectively. The device (24) is connected to the controller by signal and is used to send a signal to the controller. The controller is connected to the first solenoid valve (26) and the second solenoid valve (27) by signal and is used to identify the pressure value of the pressure detection device (24) and compare it with a preset value stored therein. The preset value stored in the controller is 2 MPa. When the pressure detection device (24) detects that the pressure of the natural gas delivered by the filter (5) is ≥ 2 MPa, the controller controls the second solenoid valve (27) to open and controls the first solenoid valve (26) to close. When the pressure detection device (24) detects that the pressure of the filter ( 5) When the pressure of the delivered natural gas is less than 2 MPa, the controller controls the first solenoid valve (26) to open and controls the second solenoid valve (27) to close; the first-stage booster pump (21) and the second-stage booster pump (22) are connected to the buffer tank (23) through a delivery pipeline; the buffer tank (23) is connected to the second-stage booster pump (25) through a delivery pipeline; the second-stage booster pump (25) is connected to the upper end of the casing (31) through a delivery pipeline; the second-stage booster pump (25) boosts the pressure of the natural gas delivered from the buffer tank (23) to 7-15 MPa.

5. A system for exploiting water-soluble gas according to claim 1, characterized in that: The natural gas source is a CNG tank truck (12), and the rated pressure of the natural gas in the CNG tank truck (12) is 20 MPa.

6. A system for exploiting water-soluble gas according to claim 5, characterized in that: The pressure regulating device is a pressure regulating skid (28), and the pressure regulating skid (28) can be used to adjust the pressure of the natural gas delivered by the CNG tank truck (12) from 20 MPa to 7-15 MPa.

7. A system for exploiting water-soluble gas according to claim 1, characterized in that: A water mixer is provided at the lower ends of the casing (31) and the oil pipe (32).

8. A system for exploiting water-soluble gas according to claim 1, characterized in that: A branch delivery pipeline is connected to the delivery pipeline connecting the drainage outlet of the gas-water separator (4) and the water injection well (6), and the branch delivery pipeline can be connected to the city heating pipeline (7).

9. A system for exploiting water-soluble gas according to claim 1, characterized in that: The transmission pipeline for external transmission at the upper end of the oil pipe (32) is connected to a gas transmission pipeline for direct external transmission to users.

10. A system for exploiting water-soluble gas according to claim 1, characterized in that: The transmission pipeline for external transmission at the upper end of the oil pipe (32) is connected to a gas generator set, and the natural gas is transmitted to users after generating electricity in the gas generator set.

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