Coal bed gas treatment system integrating power generation, mixed transportation and gas lift

Abstract

The invention relates to the technical field of coal bed gas well yield increase engineering, and particularly discloses a coal bed gas treatment system integrating power generation, mixed transportation and gas lift, which comprises a well head gas pipeline, a mixed transportation pipeline and a well head sleeve, and is characterized by further comprising a mixed transportation compression device and a gas lift compression device. According to the unit, a gas lift operation system and a mixed transportation operation system are integrated, so that mixed transportation and gas lift operation can be simultaneously carried out in one unit system, and when gas lift is not needed, the mixed transportation operation efficiency and the utilization rate of equipment are greatly improved; the air pressure in the unit can be flexibly adjusted by changing series-parallel connection according to the air inlet and exhaust pressure ratio, the number and types of system equipment are simplified to the maximum extent, the two operation requirements of air lift and mixed transportation under different air inlet and exhaust pressure ratios are met to the maximum extent, the occupied area and energy are greatly saved, and the working efficiency is improved. And the working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of enhanced production engineering for coalbed methane wells, and particularly to a coalbed methane treatment system integrating power generation, mixed transportation, and gas lift. Background Art

[0002] During the process of coalbed methane extraction, usually petroleum, natural gas, and water are extracted together. During the extraction process from the well, in order to improve the extraction efficiency, it is usually necessary to use a liquid drive compressor to pressurize and mix the three, so as to mix and output the three together to achieve the mixed transportation of oil, gas, and liquid. Moreover, in the field of coalbed methane extraction where the integration technology is very mature, the mixed transportation and gas lift of coalbed methane are often integrated into a whole system, thereby simplifying the structure of the extraction equipment, saving floor space and energy.

[0003] The current integrated system for coalbed methane mixed transportation and gas lift does not have the function of directly using the natural gas extracted from the well as energy. The entire integrated system still needs to rely on external input energy to work, and it cannot flexibly switch between gas lift and mixed transportation modes under different working conditions. The working efficiency of the integrated system for coalbed methane mixed transportation and gas lift still needs to be improved.

[0004] Therefore, it is necessary to propose a coalbed methane treatment system integrating power generation, mixed transportation, and gas lift to simplify the structure of the integrated system, further save floor space and energy, and improve the working efficiency. Summary of the Invention

[0005] The object of the present invention is to solve the problems of the existing integrated system for coalbed methane mixed transportation and gas lift, such as the redundant structure of the integrated system, waste of floor space and energy, and low working efficiency. Now, a coalbed methane treatment system integrating power generation, mixed transportation, and gas lift is provided.

[0006] The technical solution of the present invention is as follows: A coalbed methane treatment system integrating power generation, mixed transportation and gas lift, including a wellhead gas pipeline, a mixed transportation pipeline and a wellhead casing, further includes a mixed transportation compression device and a gas lift compression device. The wellhead gas pipeline is connected to a three-phase separator, and the three-phase separator is connected to a primary filter. The input ends of the mixed transportation compression device and the gas lift compression device are both connected to the primary filter. The output end of the mixed transportation compression device is respectively connected to the mixed transportation pipeline and the input end of the gas lift compression device. The output end of the gas lift compression device is respectively connected to the mixed transportation pipeline and the wellhead casing. The mixed transportation compression device includes a first mixed transportation cylinder group and a second mixed transportation cylinder group, and the first mixed transportation cylinder group and the second mixed transportation cylinder group are connected in parallel or in series. The gas lift compression device includes a first gas lift cylinder group and a second gas lift cylinder group, and the first gas lift cylinder group and the second gas lift cylinder group are connected in parallel or in series. It further includes a gas engine, a generator, a gas pipeline and a hydraulic pump. The output end of the mixed transportation compression device and the output end of the primary filter are both connected to the input end of the gas pipeline and transport natural gas into the gas pipeline. The output end of the gas pipeline is connected to the gas engine and transports natural gas to the gas engine. There is an intermediate filter on the gas pipeline. The gas engine drives the generator to generate electricity, and the gas engine drives the hydraulic pump to input an oil-gas-water three-phase mixture into the mixed transportation compression device and the gas lift compression device.

[0007] Further, it also includes an instrument air pipeline. The input end of the instrument air pipeline is connected to the output end of the gas pipeline, and the output end of the instrument air pipeline is connected to each pneumatic valve in the coalbed methane treatment system and provides a gas source for each pneumatic valve.

[0008] Further, the mixed transportation compression device and the gas lift compression device are connected with a process gas vent for relieving pressure and discharging excessive gas.

[0009] Further, it also includes a liquid collection tank. The liquid collection tank is respectively connected to the three-phase separator, the primary filter and the intermediate filter. The output end of the gas lift compression device is connected to the three-phase separator. The liquid collection tank is used to collect the liquids discharged from the three-phase separator, the primary filter and the intermediate filter, and the excessive gas in the gas lift compression device can also be discharged into the three-phase separator for three-phase separation.

[0010] Further, it also includes a connecting pipeline. One end of the connecting pipeline is connected to the mixed transportation pipeline, and the other end of the connecting pipeline is connected to the wellhead gas pipeline. The connecting pipeline can be used as a standby pipeline. When the unit fails and cannot operate temporarily, or when gas needs to be output in other situations, the connecting pipeline can directly input the gas in the wellhead gas pipeline into the mixed transportation pipeline to temporarily meet the operation requirements.

[0011] Further, the first mixed transportation cylinder group, the second mixed transportation cylinder group, the first gas lift cylinder group and the second gas lift cylinder group are respectively connected with air coolers, and the air coolers are used for cooling.

[0012] Further, the first mixed transportation cylinder group includes three cylinders in parallel, the second mixed transportation cylinder group includes one cylinder, the first gas lift cylinder group includes two cylinders in parallel, and the second gas lift cylinder group includes one cylinder.

[0013] Further, there are three hydraulic pumps. The gas engine drives the hydraulic pumps through a power take-off box, and the hydraulic pumps can drive the first mixed transportation cylinder group, the second mixed transportation cylinder group, the first gas lift cylinder group, and the second gas lift cylinder group to compress gas.

[0014] Further, the hydraulic pumps are connected with hydraulic cylinders, the hydraulic cylinders are connected with oil pumps and hydraulic oil coolers. A first reversing valve is provided between the hydraulic pumps and the mixed transportation compression device, and a second reversing valve is provided between the hydraulic pumps and the gas lift compression device.

[0015] A coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to the present invention outputs an oil-gas-water three-phase mixture extracted from the well from the wellhead gas pipeline. First, it is introduced into a three-phase separator, and the natural gas enters a primary filter for filtration. Then, the primary filter is simultaneously connected to a gas pipeline, a mixed transportation compression device and a gas lift compression device. By adjusting the valves, the flow direction of the natural gas can be controlled. On the one hand, the natural gas entering the gas pipeline is used to drive the gas engine after passing through an intermediate filter, realizing the self-extraction and self-use of the gas, and no longer relying on external gas sources to maintain operation, which simplifies the structure of the unit.

[0016] On the other hand, the gas output from the primary filter is simultaneously connected to the mixed transportation compression device and the gas lift compression device. Open the valve between the mixed transportation compression device and the primary filter, and then open the valve between the gas lift compression device and the primary filter. The natural gas can be output to the mixed transportation pipeline through the mixed transportation compression device for collection, or the natural gas can be injected into the wellhead casing through the gas lift compression device for gas lift; during non-gas lift operations, open the valve between the gas lift compression device and the mixed transportation pipeline, so that the mixed transportation compression device and the gas lift compression device are in parallel, and they can jointly transport natural gas into the mixed transportation pipeline, greatly improving the mixed transportation rate. Specifically: When the intake and exhaust pressure ratio of the unit is less than or equal to the standard intake and exhaust pressure ratio, and the unit only performs mixed transportation, the gas lift compression device and the mixed transportation compression device only need to perform primary compression. Therefore, the gas lift compression device and the mixed transportation compression device are in parallel, and the first mixed transportation cylinder group and the second mixed transportation cylinder group are in parallel, and the first gas lift cylinder group and the second gas lift cylinder group are also in parallel, that is, it is equivalent to all four cylinder groups being in parallel. At this time, a high recovery speed can be ensured, the recovery time can be saved, and the mixed transportation operation efficiency can be greatly improved; When the intake and exhaust pressure ratio of the unit is less than or equal to the standard intake and exhaust pressure ratio, and the unit conducts both multiphase transportation and gas lift simultaneously, only one-stage compression is required for multiphase transportation to meet the requirements. However, the pressure required for gas lift is relatively high, and the gas needs to be compressed in the gas lift compression device at the second stage before it can be introduced into the wellhead casing. Therefore, the first gas lift cylinder group and the second gas lift cylinder group are in series at this time to achieve second-stage compression, meet the requirements of gas lift operations, and realize the simultaneous operation of gas lift and multiphase transportation; When the intake and exhaust pressure ratio of the unit is greater than the standard intake and exhaust pressure ratio, and the unit only conducts multiphase transportation, the gas in the unit needs to be compressed at the second stage to meet the requirements of multiphase transportation at this time. Therefore, the first multiphase transportation cylinder group and the second multiphase transportation cylinder group in the multiphase transportation compression device are in series to achieve second-stage compression, and the second gas lift cylinder group and the first gas lift cylinder group in the gas lift compression device are in series to achieve second-stage compression. The multiphase transportation compression device and the gas lift compression device are in parallel to achieve simultaneous multiphase transportation through double pipelines and improve the multiphase transportation efficiency; When the intake and exhaust pressure ratio of the unit is greater than the standard intake and exhaust pressure ratio, and the unit conducts both multiphase transportation and gas lift simultaneously, the gas in the unit needs to be compressed at the second stage to meet the requirements of multiphase transportation at this time. Therefore, the first multiphase transportation cylinder group and the second multiphase transportation cylinder group in the multiphase transportation compression device are in series to achieve second-stage compression, and the second gas lift cylinder group and the first gas lift cylinder group in the gas lift compression device are in series to meet the requirements of gas lift. The multiphase transportation compression device and the gas lift compression device are in series. One branch of the gas after the second-stage compression of the multiphase transportation compression device is input into the multiphase transportation pipeline, and another branch enters the input end of the gas lift compression device. After the gas lift compression device re-compresses the gas that has been compressed by the multiphase transportation compression device at the second stage, it meets the pressure requirements of gas lift and is introduced into the wellhead casing for gas lift operations.

[0017] Compared with the traditional technology, the unit integrates the gas lift operation system and the multiphase transportation operation system, enabling the simultaneous operation of multiphase transportation and gas lift in one unit system. When gas lift is not required, the gas lift compression device can also be used for multiphase transportation, greatly improving the multiphase transportation efficiency and the utilization rate of equipment. Moreover, according to the size of the intake and exhaust pressure ratio, the internal air pressure of the unit can be flexibly adjusted by changing the series-parallel connection. The unit has a high degree of integration, simplifies the quantity and types of system equipment to the greatest extent, and meets the requirements of both gas lift and multiphase transportation operations under different intake and exhaust pressure ratios to the greatest extent, greatly saving the floor area and energy and improving the work efficiency. Brief Description of the Drawings

[0018] Figure 1 is a structural reference diagram of the present invention; Figure 2 is a process flow diagram of the power system of the present invention.

[0019] Reference numerals: 1, wellhead gas pipeline; 2, multiphase transportation pipeline; 3, wellhead casing; 4, multiphase transportation compression device; 5, gas lift compression device; 6, three-phase separator; 7, primary filter; 8, first multiphase transportation cylinder group; 9, second multiphase transportation cylinder group; 10, first gas lift cylinder group; 11, second gas lift cylinder group; 12, generator; 13, gas pipeline; 14, hydraulic pump; 15, intermediate filter; 16, instrument air pipeline; 17, process gas vent; 18, liquid collection tank; 19, connecting pipeline; 20, air cooler; 21, hydraulic cylinder; 22, oil pump; 23, hydraulic oil cooler; 24, first reversing valve; 25, second reversing valve; 26, gas engine. Detailed implementation mode

[0020] In order to make the technical means, technical features, invention purpose and technical effects achieved by the present invention easy to understand, the present invention will be further described below with reference to specific drawings.

[0021] Embodiment 1: As Figure 1 and Figure 2 shown, this embodiment provides a coalbed methane treatment system integrating power generation, multiphase transportation and gas lift, including a wellhead gas pipeline 1, a multiphase transportation pipeline 2 and a wellhead casing 3, and further including a multiphase transportation compression device 4 and a gas lift compression device 5. The wellhead gas pipeline 1 is connected to a three-phase separator 6, the three-phase separator 6 is connected to a primary filter 7, the input ends of the multiphase transportation compression device 4 and the gas lift compression device 5 are both connected to the primary filter 7, the output end of the multiphase transportation compression device 4 is respectively connected to the multiphase transportation pipeline 2 and the input end of the gas lift compression device 5, the output end of the gas lift compression device 5 is respectively connected to the multiphase transportation pipeline 2 and the wellhead casing 3. The multiphase transportation compression device 4 includes a first multiphase transportation cylinder group 8 and a second multiphase transportation cylinder group 9, the first multiphase transportation cylinder group 8 and the second multiphase transportation cylinder group 9 are in parallel or series connection. The gas lift compression device 5 includes a first gas lift cylinder group 10 and a second gas lift cylinder group 11, the first gas lift cylinder group 10 and the second gas lift cylinder group 11 are in parallel or series connection. It also includes a gas engine 26, a generator 12, a gas pipeline 13 and a hydraulic pump 14. The output end of the multiphase transportation compression device 4 and the output end of the primary filter 7 are both connected to the input end of the gas pipeline 13 and transport natural gas into the gas pipeline 13. The output end of the gas pipeline 13 is connected to the gas engine 26 and transports natural gas to the gas engine 26. An intermediate filter 15 is provided on the gas pipeline 13. The gas engine 26 drives the generator 12 to generate electricity, and the gas engine 26 drives the hydraulic pump 14 to input an oil-gas-water three-phase mixture into the multiphase transportation compression device 4 and the gas lift compression device 5. Preferably, the primary filter 7 is a basket filter.

[0022] Preferably, it further includes an instrument air pipeline 16. The input end of the instrument air pipeline 16 is connected to the output end of the gas pipeline 13, and the output end of the instrument air pipeline 16 is connected to each pneumatic valve in the coalbed methane treatment system to supply air source to each pneumatic valve.

[0023] Preferably, the mixed transportation compression device 4 and the gas lift compression device 5 are connected with a process gas vent 17 for relieving pressure to discharge excessive gas.

[0024] Preferably, it further includes a liquid collection tank 18. The liquid collection tank 18 is respectively connected to the three-phase separator 6, the primary filter 7 and the intermediate filter 15. The output end of the gas lift compression device 5 is connected to the three-phase separator 6. The liquid collection tank 18 is used to collect the liquids discharged from the three-phase separator 6, the primary filter 7 and the intermediate filter 15, and the excessive gas in the gas lift compression device 5 can also be discharged into the three-phase separator 6 for three-phase separation.

[0025] Preferably, it further includes a connecting pipeline 19. One end of the connecting pipeline 19 is connected to the mixed transportation pipeline 2, and the other end of the connecting pipeline 19 is connected to the wellhead gas pipeline 1. The connecting pipeline 19 can be used as a standby pipeline. When the unit fails and cannot operate temporarily, or when gas needs to be output in other situations, the connecting pipeline 19 can directly input the gas in the wellhead gas pipeline 1 into the mixed transportation pipeline 2 to temporarily meet the operation requirements.

[0026] Preferably, the first mixed transportation cylinder group 8, the second mixed transportation cylinder group 9, the first gas lift cylinder group 10 and the second gas lift cylinder group 11 are respectively connected with an air cooler 20 for cooling.

[0027] Preferably, the first mixed transportation cylinder group 8 includes three cylinders connected in parallel, the second mixed transportation cylinder group 9 includes one cylinder, the first gas lift cylinder group 10 includes two cylinders connected in parallel, and the second gas lift cylinder group 11 includes one cylinder.

[0028] Preferably, as Figure 2 shown, there are three hydraulic pumps 14. The gas engine 26 drives the hydraulic pumps 14 to work through a power take-off box, and the hydraulic pumps 14 can drive the first mixed transportation cylinder group 8, the second mixed transportation cylinder group 9, the first gas lift cylinder group 10 and the second gas lift cylinder group 11 to compress gas.

[0029] Preferably, the hydraulic pump 14 is connected with a hydraulic cylinder 21. The hydraulic cylinder 21 is connected with an oil pump 22 and a hydraulic oil cooler 23. A first reversing valve 24 is provided between the hydraulic pump 14 and the mixed transportation compression device 4, and a second reversing valve 25 is provided between the hydraulic pump 14 and the gas lift compression device 5.

[0030] During the operation of the present invention, first, the oil-gas-water three-phase mixture produced from the well is output from the wellhead gas pipeline 1 and first introduced into the three-phase separator 6. The natural gas enters the primary filter 7 for filtration. Then, the primary filter 7 is simultaneously connected to the gas pipeline 13, the mixed transportation compression device 4, and the gas lift compression device 5. By adjusting the valves, the flow direction of the natural gas can be controlled. On the one hand, the natural gas entering the gas pipeline 13 is used to drive the gas engine 26 after being filtered by the intermediate filter 15, realizing the self-production and self-use of the gas and no longer relying on external gas sources to maintain operation, which simplifies the structure of the unit.

[0031] On the other hand, the gas output from the primary filter 7 is simultaneously connected to the mixed transportation compression device 4 and the gas lift compression device 5. Open the valve between the mixed transportation compression device 4 and the primary filter 7, and then open the valve between the gas lift compression device 5 and the primary filter 7. The natural gas can be output to the mixed transportation pipeline 2 through the mixed transportation compression device 4 for collection, or the natural gas can be injected into the wellhead casing 3 through the gas lift compression device 5 for gas lift; during non-gas lift operations, open the valve between the gas lift compression device 5 and the mixed transportation pipeline 2, so that the mixed transportation compression device 4 and the gas lift compression device 5 are in parallel and can jointly transport natural gas into the mixed transportation pipeline 2, greatly improving the mixed transportation rate. The specific working process is as follows: Situation 1: When the intake and exhaust pressure ratio of the unit is less than or equal to the standard intake and exhaust pressure ratio and the unit only performs mixed transportation, the gas lift compression device 5 and the mixed transportation compression device 4 only need to perform primary compression. Therefore, the gas lift compression device 5 and the mixed transportation compression device 4 are in parallel, and the first mixed transportation cylinder group 8 and the second mixed transportation cylinder group 9 are in parallel, and the first gas lift cylinder group 10 and the second gas lift cylinder group 11 are also in parallel, that is, it is equivalent to all four cylinder groups being in parallel. At this time, a high recovery speed can be ensured, the recovery time can be saved, and the mixed transportation operation efficiency can be greatly improved; Situation 2: When the intake and exhaust pressure ratio of the unit is less than or equal to the standard intake and exhaust pressure ratio and the unit simultaneously performs mixed transportation and gas lift, the mixed transportation only needs to perform primary compression to meet the requirements, but the pressure required for gas lift is relatively high, and the gas needs to be compressed by the gas lift compression device 5 at the second stage before being introduced into the wellhead casing 3. Therefore, the first gas lift cylinder group 10 and the second gas lift cylinder group 11 are in series at this time to achieve secondary compression, meet the requirements of gas lift operations, and realize the simultaneous operation of gas lift and mixed transportation; Case 3: When the intake and exhaust pressure ratio of the unit is greater than the standard intake and exhaust pressure ratio and the unit only performs mixed transportation, the gas in the unit needs to be compressed in two stages to meet the requirements of mixed transportation at this time. Therefore, the first mixed transportation cylinder group 8 and the second mixed transportation cylinder group 9 in the mixed transportation compression device 4 are connected in series to achieve two-stage compression. The second gas lift cylinder group 11 and the first gas lift cylinder group 10 in the gas lift compression device 5 are connected in series to achieve two-stage compression. The mixed transportation compression device 4 and the gas lift compression device 5 are connected in parallel to achieve simultaneous mixed transportation through double pipelines and improve the mixed transportation efficiency; Case 4: When the intake and exhaust pressure ratio of the unit is greater than the standard intake and exhaust pressure ratio and the unit performs both mixed transportation and gas lift simultaneously, the gas in the unit needs to be compressed in two stages to meet the requirements of mixed transportation at this time. Therefore, the first mixed transportation cylinder group 8 and the second mixed transportation cylinder group 9 in the mixed transportation compression device 4 are connected in series to achieve two-stage compression. The second gas lift cylinder group 11 and the first gas lift cylinder group 10 in the gas lift compression device 5 are connected in series to meet the gas lift requirements. The mixed transportation compression device 4 and the gas lift compression device 5 are connected in series. One branch of the gas after two-stage compression in the mixed transportation compression device 4 is input into the mixed transportation pipeline 2, and another branch enters the input end of the gas lift compression device 5. After the gas that has been compressed by the mixed transportation compression device 4 is compressed again in two stages by the gas lift compression device 5 to meet the pressure requirements of gas lift, it is introduced into the wellhead casing 3 for gas lift operation.

[0032] The above-mentioned standard intake and exhaust pressure ratio is 3.

[0033] The installation operation process of this equipment is as follows: After the equipment arrives at the site, it is assembled. After assembly, the skid of the unit is connected to the customer's peripheral pipelines. The main connection part of the pipelines uses seamless steel pipes. After the connection is completed, to ensure the start of the engine and the source of instrument air, the two air intake ports are internally integrated and positioned after the basket filter of the unit. In this way, the gas entering the unit is pre-treated to obtain relatively clean gas, and then after being filtered by the intermediate filter 15 and corresponding pressure reduction operations, it reaches the gas required to start the engine to provide power for the engine and meet the quality requirements of the instrument air of the unit. Pressure reducing valves are installed at the inlets of these two pipelines to reduce the natural gas in the pipelines to an appropriate pressure for the unit to use. The unit can obtain starting gas, fuel gas, and instrument air and start. At this time, the unit is in an idle state.

[0034] At this time, start the natural gas engine. The rear end of the natural gas engine drives the hydraulic pump 14 through the transfer case. The hydraulic pump 14 provides power for the hydraulic system, and then drives two liquid-driven piston compressors to work simultaneously. The front end of the engine directly drives the generator set 12 to supply power to electrical equipment such as PLC and fans. The cooler timely dissipates the heat generated during the operation of the engine and the compressor to ensure the normal operation of the natural gas engine. At this time, open the intake valve of the compressor unit, natural gas enters the compressor unit, close the bypass valve of the unit, and the compressed gas enters the long-distance pipeline or the casing through the exhaust valve.

[0035] The present invention employs a liquid-driven piston compressor unit, which adopts an integrated skid-mounted design and includes the above-mentioned multiphase transportation compression device 4, gas lift compression device 5, gas engine 26, generator 12, hydraulic pump 14, air cooler 20, hydraulic cylinder 21, oil pump 22, cooler, first reversing valve 24 and second reversing valve 25, and is used for gas lift compression operations and multiphase transportation compression operations. The advantages of this design compared with the traditional coalbed methane extraction and recovery methods are as follows: 1. The skid-mounted layout integrates the processing, gas lift, and multiphase transportation equipment on one skid base, saving space; 2. The entire unit is equipped with a gas engine 26 and a generator 12, which adopt direct drive, have high mechanical efficiency, low failure probability, and do not require additional on-site power, adapting to the operating conditions of natural gas stations without power resources; 3. The overall skid-mounted layout only requires connecting the pipelines for inlet, outlet, sewage discharge, and venting to complete the on-site operation preparation, with a short operation preparation time; 4. Using the gas engine 26 as the main drive and the natural gas treated by the three-phase separator 6, the on-site source is taken, and the recovery operation cost is low; 5. With zero demand for on-site public resources such as the gas engine 26, air cooler 20, and generator 12, the unit has a high integration level, a simple system structure, and saves floor area and energy; 6. The gas intake of the gas engine 26 is taken from the outlet of the pre-treatment, and the gas source is clean, ensuring the stability of the entire unit during the recovery process; 7. The plate-fin cooler is used for the cooling water circuit of the engine and the cooling of the hydraulic oil, which is small in volume and high in efficiency. The process gas cooler is a tube-box type finned tube air cooler 20, which has high pressure resistance and good safety. The traditional finned tube heat exchanger is transformed into two air coolers 20, namely the plate-fin type and the finned tube type. By placing each air cooler 20 close to its own heat exchange unit, the overall pipeline layout becomes more reasonable; 8. The unit is also equipped with a heat preservation house and heating equipment, and the unit equipment can operate normally in rainy and snowy weather, with a minimum operating temperature reaching -30°C; 9. The unit can realize two processes of gas lift and multiphase transportation. When the casing pressure and tubing pressure difference of the gas well are large and there is liquid accumulation that requires gas lift, adjust the pneumatic valves of each pipeline, connect the multiphase transportation compression device 4 in series to the input end of the gas lift compression device 5, switch one of the multiphase transportation compressors into a gas lift compressor, use the clean gas source after multiphase transportation compression as the inlet of gas lift compression, and inject high-pressure gas into the gas well blocked by liquid through the compressor to remove the bottom-hole liquid accumulation. The multiphase transportation compressor of the unit adopts a single-stage compression mode under normal pressure ratio to ensure the natural gas processing capacity of the unit. As the development wellhead pressure decreases, the pressure ratio gradually increases. To ensure that the unit can cover more coalbed methane wells, a multi-stage switching setting with pressure ratio control is adopted. When the inlet and outlet pressure ratios are high, it is switched to two-stage compression to ensure the compression temperature and exhaust pressure.One - level / Two - level switching can be achieved through one - key control by PLC to meet the requirements of multiple working conditions; 10. This unit provides a skid - mounted fuel - driven gas - liquid mixed - flow and gas - lift integrated compressor. Both the gas - lift compressor and the mixed - flow compressor adopt a five - stage two - stage compression, with obvious energy - saving and power - saving effects; 11. This unit can achieve closed - type sewage discharge or on - site sewage discharge. After the gas coming from the production well passes through the primary filter 7, some liquids are separated. The separated liquids can either be directly pressed into the production pipeline network by a pump or collected into the liquid collection tank 18 according to requirements; 12. The front end of the gas engine 26 drives the generator 12, and the rear end is connected with a flywheel and drives the hydraulic pump 14 to work through a transfer case. The hydraulic pump 14 is driven in a direct - drive manner, with high operation efficiency. The generator 12 can solve the power consumption problems of the fan, PLC, heater, etc., and no external power input is required on - site.

[0036] The air cooler 20, also known as the process gas cooler: adopts a tube - box structure to dissipate the heat generated during the gas pressurization process in a timely manner. This cooler is driven by a variable - frequency motor and uses the temperature feedback of the medium at the cooler outlet. When the outlet medium temperature is high, the speed of the variable - frequency motor increases; when the outlet medium temperature is low, the speed of the variable - frequency motor decreases. The temperature stability after cooling is maintained through closed - loop feedback to meet the requirements of the pipeline network; The gas engine 26 is also equipped with an engine cooler: adopts a plate - fin structure, uses a variable - frequency fan to drive the ventilation volume, cools the water circuit of the gas engine 26, and dissipates the heat generated during the operation of the gas engine 26 in a timely manner to ensure the stable operation of the engine; The hydraulic oil cooler 23: adopts a plate - fin structure, uses a variable - frequency fan to drive the ventilation volume, cools the hydraulic oil of the piston - type compressor with a coolant, and dissipates the heat generated during the operation of the compressor in a timely manner to ensure the stable operation of the compressor; The tracing system: heats and insulates the engine and the compressor, enabling the unit to adapt to low - temperature working conditions, with the lowest working ambient temperature reaching - 35°C.

[0037] In addition, the compressor cylinder in this equipment adopts an oil-free lubrication method, and the gas chamber seal and oil chamber seal adopt multi-stage seals, which can avoid oil pollution to natural gas, reduce the pollution damage of oil stains to the compressor, pipeline and other equipment, eliminate the lubrication equipment and oil-gas separation equipment, with a simple structure and few failure points. This type of compressor has a unique three-phase mixing and transportation special gas valve, which can harmlessly pass gaseous, liquid and solid particles with a particle size ≤ 0.5 mm, and there is no limit on their content ratio. The pre-stage three-phase separator 6 is equipped with a tracing heating band, and the hydraulic oil tank is equipped with a heater, enabling the unit to adapt to a low-temperature working environment. The starting gas and fuel gas of the natural gas engine are taken from the gas after the pre-stage treatment of the unit, so the gas source is relatively clean, thus ensuring the stability of the fuel gas and starting gas and ensuring the most stable and reliable operation of the unit. The unit is equipped with an automatic sewage discharge system. The separated liquid separated from the separator is discharged to the sewage pond or the liquid collection tank 18 through the drain pipeline for on-site collection; the separated liquid can also be injected into the export pipeline through a high-pressure plunger pump to achieve closed mixing and transportation.

[0038] Compared with the traditional technology, this unit integrates the gas lift operation system and the mixing and transportation operation system, enabling the simultaneous implementation of mixing and transportation and gas lift operations in a single unit system. When gas lift is not required, the gas lift compression device 5 can also be used for mixing and transportation, greatly improving the efficiency of the mixing and transportation operation and the utilization rate of the equipment. Moreover, according to the size of the intake and exhaust pressure ratio, the air pressure inside the unit can be flexibly adjusted by changing the series-parallel connection. This unit has a high degree of integration, simplifies the quantity and types of system equipment to the greatest extent, and meets the requirements of both gas lift and mixing and transportation operations under different intake and exhaust pressure ratios to the greatest extent, greatly saving the floor area and energy and improving the work efficiency.

[0039] The above is only a preferred embodiment of the present invention and is not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention shall fall within the technical scope of the present invention.

Claims

1. A coalbed methane treatment system integrating power generation, mixed transportation and gas lift, comprising a wellhead gas pipeline (1), a mixed transportation pipeline (2) and a wellhead casing (3), characterized in that: It also includes a multiphase transportation compression device (4) and a gas lift compression device (5). The wellhead gas pipeline (1) is connected to a three-phase separator (6), and the three-phase separator (6) is connected to a primary filter (7). The input ends of the multiphase transportation compression device (4) and the gas lift compression device (5) are both connected to the primary filter (7). The output end of the multiphase transportation compression device (4) is respectively connected to the multiphase transportation pipeline (2) and the input end of the gas lift compression device (5). The output end of the gas lift compression device (5) is respectively connected to the multiphase transportation pipeline (2) and the wellhead casing (3); The multiphase transportation compression device (4) includes a first multiphase transportation cylinder group (8) and a second multiphase transportation cylinder group (9), and the first multiphase transportation cylinder group (8) and the second multiphase transportation cylinder group (9) are in parallel or series connection. The gas lift compression device (5) includes a first gas lift cylinder group (10) and a second gas lift cylinder group (11), and the first gas lift cylinder group (10) and the second gas lift cylinder group (11) are in parallel or series connection; It also includes a gas engine (26), a generator (12), a gas pipeline (13), and a hydraulic pump (14). The output end of the multiphase transportation compression device (4) and the output end of the primary filter (7) are both connected to the input end of the gas pipeline (13) and transport natural gas into the gas pipeline (13). The output end of the gas pipeline (13) is connected to the gas engine (26) and transports natural gas to the gas engine (26). An intermediate filter (15) is provided on the gas pipeline (13). The gas engine (26) drives the generator (12) to generate electricity, and the gas engine (26) drives the hydraulic pump (14) to input an oil-gas-water three-phase mixture into the multiphase transportation compression device (4) and the gas lift compression device (5).

2. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: It also includes an instrument air pipeline (16). The input end of the instrument air pipeline (16) is connected to the output end of the gas pipeline (13), and the output end of the instrument air pipeline (16) is connected to each pneumatic valve in the coalbed methane treatment system and provides a gas source for each pneumatic valve.

3. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: The multiphase transportation compression device (4) and the gas lift compression device (5) are connected to a process gas vent (17).

4. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: It also includes a liquid collection tank (18). The liquid collection tank (18) is respectively connected to the three-phase separator (6), the primary filter (7), and the intermediate filter (15), and the output end of the gas lift compression device (5) is connected to the three-phase separator (6).

5. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: It also includes a connecting pipeline (19). One end of the connecting pipeline (19) is connected to the multiphase transportation pipeline (2), and the other end of the connecting pipeline (19) is connected to the wellhead gas pipeline (1).

6. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: The first multiphase transportation cylinder group (8), the second multiphase transportation cylinder group (9), the first gas lift cylinder group (10), and the second gas lift cylinder group (11) are respectively connected to an air cooler (20).

7. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 6, characterized in that: The first multiphase transportation cylinder group (8) includes three cylinders in parallel, and the second multiphase transportation cylinder group (9) includes one cylinder; The first gas lift cylinder group (10) includes two cylinders in parallel, and the second gas lift cylinder group (11) includes one cylinder.

8. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 1, characterized in that: There are three hydraulic pumps (14), and the gas engine (26) drives the hydraulic pumps (14) to work through a power take-off box.

9. The coalbed methane treatment system integrating power generation, mixed transportation and gas lift according to claim 8, characterized in that: The hydraulic pump (14) is connected to a hydraulic cylinder (21), the hydraulic cylinder (21) is connected to an oil pump (22) and a hydraulic oil cooler (23), a first reversing valve (24) is provided between the hydraulic pump (14) and the multiphase transportation compression device (4), and a second reversing valve (25) is provided between the hydraulic pump (14) and the gas lift compression device (5).

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