A dual pressure system for a gas gathering station and a gas gathering method thereof

Abstract

The present invention belongs to the technical field of oil and gas fields, and specifically provides a dual-pressure system for a gas gathering station and a gas gathering method thereof. In the early stage of gas gathering, a medium-pressure gas gathering unit is used to gather gas; in the middle stage of gas gathering, a medium-pressure gas gathering unit and a low-pressure gas gathering unit are used to gather gas together; in the late stage of gas gathering, a low-pressure gas gathering unit is used to gather gas, which solves the problem that in the prior art, a large well cluster development method is adopted for tight gas fields. Since the initial gas production of a single well cluster is high, the construction scale of the ground system is large, and the investment in the construction of a single well and a gas gathering station is high, as the pressure and gas volume of the gas well decrease, the matching degree of the ground built system decreases, and the adaptability to the later development and construction becomes worse. The alcohol injection process is combined with dual-pipe dual-pressure gathering and transportation to form a mixed gas gathering process of "downhole throttling + concentrated alcohol injection in the early stage + pressurized production in the later stage", which effectively reduces the diameter of the gas production pipeline, improves the matching degree of the pipeline to the pressure system and the adaptability of the process, and the selection of the pressurization time is more economical and has stronger adaptability to subsequent development and construction.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas fields, and in particular relates to a dual-pressure system of a gas gathering station and a gas gathering method thereof. Background Art

[0002] The downstream market demand for natural gas is strong, and the gas supply pressure of Changqing Gas Field has increased. In 2019, the gas production reached 412×10 8 m 3 / a, especially in winter, when ensuring gas supply involves livelihood projects, the daily gas demand far exceeds the normal production level.

[0003] According to the second accelerated development goal of Changqing Oilfield Branch and the plan of the Group Company, by 2020, the natural gas production in Changqing Gas Area will reach 420×10 8 m 3 The Sulige gas field is rich in tight gas resources and is the key to ensuring 420×10 8 m 3 / aAn important guarantee for increasing and stabilizing production.

[0004] In 2019, the Changqing Gas District began to build a tight gas demonstration area, focusing on the development of large horizontal well clusters. The tight gas demonstration area deployed a total of 30×10 8 m 3 , among which the tight gas production capacity of Sudongnan block is 20×10 8 m 3 Due to the characteristics of high production, high pressure and high gas well decline rate of the horizontal wells in Southeast Jiangsu, the initial production averaged about 50,000m 3 / d, after 4-5 years of continuous production, the average output drops to about 10,000m 3 / d. The large well cluster development method is adopted. The initial gas production of a single well cluster is high, the ground system construction scale is large, and the investment in single well and gas gathering station construction is high. As the gas well pressure and gas volume decrease, the matching degree of the existing ground system decreases, and the adaptability of later development and construction becomes worse. A standardized model of gas gathering stations for horizontal wells and large well cluster development in tight gas fields is proposed. Summary of the invention

[0005] The present invention provides a dual-pressure system for a gas gathering station and a gas gathering method thereof. The purpose is to overcome the problem that in the prior art, a large well cluster development method is used for tight gas fields. Due to the high initial gas production of a single well cluster, the large scale of ground system construction, and the high investment in single well and gas gathering station construction, as the gas well pressure and gas volume decrease, the matching degree of the ground built system decreases and the adaptability of the later development and construction becomes poor.

[0006] To this end, the present invention provides a dual-pressure system for a gas gathering station, including a medium-pressure gas gathering unit and a low-pressure gas gathering unit.

[0007] The medium-pressure gas collection unit includes a medium-pressure gas production main, a medium-pressure station entry unit and a medium-pressure separator. The inlet of the medium-pressure station entry unit is connected to the gas inlet of the medium-pressure gas production main, and the outlet of the medium-pressure station entry is connected to the inlet of the medium-pressure separator.

[0008] The low-pressure gas gathering unit includes a low-pressure gas production main pipeline, a low-pressure station entry area unit, a low-pressure separator and a compressor. The inlet of the low-pressure station entry area unit is connected to the gas inlet of the low-pressure gas production main pipeline, the outlet of the low-pressure station entry area unit is connected to the inlet of the low-pressure separator, and the gas outlet of the low-pressure separator is connected to the inlet of the compressor; the outlet of the medium-pressure separator and the outlet of the compressor are combined through the gas gathering branch line for external transmission.

[0009] Furthermore, it also includes a meter, and the outlet of the medium-pressure separator and the outlet of the compressor are both connected to the meter.

[0010] Furthermore, it also includes a pipe cleaner, through which the medium-pressure station entry area unit is connected to the medium-pressure separator, and the low-pressure station entry area unit is connected to the low-pressure separator through the pipe cleaner.

[0011] Furthermore, it also includes an alcohol injection device and a methanol tank, the outlet of the methanol tank is connected to the inlet of the alcohol injection device, and the outlet of the alcohol injection device is connected to the alcohol injection port of the medium-pressure gas production main.

[0012] Furthermore, it also includes a flash tank, and the medium-pressure separator, low-pressure separator and compressor are all connected to the flash tank through a sewage pipeline.

[0013] Furthermore, it also includes a venting device, wherein the medium-pressure station entry area unit, the medium-pressure separator, the low-pressure station entry area unit, the low-pressure separator, the compressor, the pipe cleaner, the flash tank and the meter are all connected to the venting device through a venting pipeline.

[0014] Furthermore, it also includes a liquid separator device, wherein the medium-pressure station entry area unit, medium-pressure separator, low-pressure station entry area unit, low-pressure separator, compressor, pipe cleaner, flash tank and meter are all connected to the inlet of the liquid separator device through a venting pipeline, and the gas outlet of the liquid separator device is connected to the venting device.

[0015] Furthermore, it also includes a produced liquid storage tank, and the liquid outlets of the pipe cleaner, the liquid separator tank and the flash tank are all connected to the produced liquid storage tank through a sewage pipeline.

[0016] Furthermore, it also includes a flame arrester device, and the methanol tank and the produced liquid storage tank are both connected to the flame arrester device.

[0017] A gas gathering method of a dual-pressure system of a gas gathering station, wherein in the early stage of gas gathering, a medium-pressure gas gathering unit is used to gather gas; in the middle stage of gas gathering, a medium-pressure gas gathering unit and a low-pressure gas gathering unit are used to gather gas together; in the late stage of gas gathering, a low-pressure gas gathering unit is used to gather gas;

[0018] The gas collection method of the medium-pressure gas collection unit is as follows: the incoming gas from the medium-pressure gas production main enters the medium-pressure station entry unit, and after the medium-pressure station entry unit and the pipeline are cleaned by a pig, the incoming gas enters the medium-pressure separator for gas-liquid separation, and the separated gas is measured by a meter and then transported to the next gas collection station or processing plant;

[0019] The gas gathering method of the low-pressure gas gathering unit is as follows: the incoming gas from the low-pressure gas production main enters the low-pressure station entry area unit, and after the low-pressure station entry area unit and pipeline are cleaned by the pig, the incoming gas enters the low-pressure separator for gas-liquid separation, and the separated gas is pressurized by the compressor, measured by the meter, and then transported to the next gas gathering station;

[0020] The medium-pressure station entry area unit, pig, medium-pressure separator, meter, low-pressure station entry area, low-pressure separator, compressor and flash tank are all connected to the separator tank through the venting pipeline. The venting gas is separated into gas and liquid through the separator tank, and the separated gas enters the venting device for venting;

[0021] The liquid separated by the medium-pressure separator, the liquid separated by the low-pressure separator and the discharge liquid of the compressor enter the flash tank for flash evaporation. The liquid after flash evaporation, the liquid in the pipe cleaner and the liquid separated by the liquid separator are transported to the produced liquid storage tank through the sewage pipeline for storage.

[0022] Beneficial effects of the present invention: The dual-pressure system and gas gathering method of the gas gathering station provided by the present invention adopts medium-pressure gas gathering units to gather gas in the early stage of gas gathering; adopts medium-pressure gas gathering units and low-pressure gas gathering units to gather gas together in the middle stage of gas gathering; and adopts low-pressure gas gathering units to gather gas in the late stage of gas gathering; a "dual-pipe dual-pressure" operation model is formed, that is, two gas production pipelines (medium-pressure gas production main pipe and low-pressure gas production main pipe) are laid from the well site to the station site, one large and one small, and the gas gathering station is considered to operate at medium and low pressure dual pressures, so that the pipe diameter and equipment specifications during construction can be reduced. When the initial pressure is high, medium pressure (medium-pressure gas gathering unit gas gathering) is used for operation, and alcohol is centrally injected into the medium-pressure gas production main pipe in the station; in the middle stage, as the pressure of the connected wells decreases The production of newly connected wells is adjusted to mixed operation of medium and low pressure (medium-pressure gas gathering unit gas gathering and low-pressure gas gathering unit gas gathering), and the pipeline series connection mode is flexibly adjusted to achieve medium and low pressure co-transmission. In the later stage, they are all adjusted to low pressure operation and pressurized in the station to meet production requirements. This process is a dual-pressure system mixed gas gathering process optimized by combining the geological characteristics and economic efficiency of tight gas horizontal well development. It adopts alcohol injection technology in combination with dual-pipe dual-pressure gathering and transportation, forming a mixed gas gathering process of "downhole throttling + early concentrated alcohol injection + later pressurized production", which effectively reduces the diameter of the gas production pipeline, improves the matching degree of the pipeline to the pressure system and the adaptability of the process, and the selection of pressurization time is more economical and has stronger adaptability to subsequent development and construction;

[0023] The dual-pressure system of the gas gathering station of the present invention comprises a medium-pressure gas production main pipe, a medium-pressure station entry unit, a medium-pressure separator, a low-pressure gas production main pipe, a low-pressure station entry unit, a low-pressure separator, a compressor, a pipe cleaner, an alcohol injection device and a methanol tank, a venting device, a produced liquid storage tank, a flame arrester device, a flash tank, and a liquid separator. The above devices are respectively fixedly connected in the gas gathering station, and through mutual connection, functions such as gas gathering, separation, compression, metering, pipe cleaning, external transmission, venting, and liquid discharge can be realized;

[0024] The gas gathering method of the dual-pressure system of the gas gathering station of the present invention adopts an alcohol injection process in conjunction with a medium- and low-pressure mixed gas gathering process of dual-pipe dual-pressure gathering and transportation, dual-pipe dual-pressure gas production outside the station, and dual-pressure gas gathering in the station. Alcohol is injected centrally in the early stage and pressurized production is carried out in the later stage. The matching degree of the ground construction pressure system is higher, the timing of pressurization is more economical, the investment cost of ground construction is greatly reduced, the adaptability of ground system development is greatly improved, the production and operation costs and the energy consumption costs of system operation are reduced, each area can be easily modularized, the single-unit installation cost is reduced, the occupation of arable land and damage to the ecological environment are reduced, and the overall maintenance of the system is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail below with reference to the accompanying drawings.

[0026] Figure 1 is a gas gathering process flow chart of a dual pressure system of a gas gathering station in Example 4;

[0027] Figure 2 This is the process flow chart of the early stage of gas gathering in the dual pressure system of the gas gathering station;

[0028] Figure 3 This is the process flow chart of the mid-stage gas gathering of the dual pressure system of the gas gathering station;

[0029] Figure 4 It is a process flow chart of the later stage of gas gathering in the dual-pressure system of a gas gathering station. DETAILED DESCRIPTION

[0030] Embodiment 1:

[0031] like Figure 1 As shown, a dual-pressure system of a gas gathering station includes a medium-pressure gas gathering unit and a low-pressure gas gathering unit. The medium-pressure gas gathering unit includes a medium-pressure station entry area unit and a medium-pressure separator. The inlet of the medium-pressure station entry area unit is connected to the gas inlet of the medium-pressure gas production main pipe, and the outlet of the medium-pressure station entry area is connected to the inlet of the medium-pressure separator; the low-pressure gas gathering unit includes a low-pressure station entry area unit, a low-pressure separator and a compressor. The inlet of the low-pressure station entry area unit is connected to the gas inlet of the low-pressure gas production main pipe, the outlet of the low-pressure station entry area unit is connected to the inlet of the low-pressure separator, and the gas outlet of the low-pressure separator is connected to the inlet of the compressor; the outlet of the medium-pressure separator and the outlet of the compressor are combined through a gas gathering branch line for external transmission.

[0032] The dual-pressure system of the gas gathering station provided by the present invention adopts a medium-pressure gas gathering unit to gather gas in the early stage of gas gathering; adopts a medium-pressure gas gathering unit and a low-pressure gas gathering unit to gather gas together in the middle stage of gas gathering; and adopts a low-pressure gas gathering unit to gather gas in the late stage of gas gathering; forming a "dual-pipe dual-pressure" operation model, that is, two gas production pipelines (a medium-pressure gas production main pipe and a low-pressure gas production main pipe) are laid from the well site to the station site, one large (the medium-pressure gas production main pipe) and one small (the low-pressure gas production main pipe). The gas gathering station is considered to operate at medium and low pressure dual pressures, so that the pipe diameter and equipment specifications during construction can be reduced. When the initial pressure is high, medium pressure (medium-pressure gas gathering unit gas collection) is used for operation, and the station Centrally inject alcohol into the internal medium-pressure gas production pipeline; in the medium term, as the pressure of connected wells decreases and new wells are produced, the operation is adjusted to mixed medium and low pressure (gas gathering by medium-pressure gas gathering unit and gas gathering by low-pressure gas gathering unit), and the pipeline series connection method is flexibly adjusted to achieve medium and low pressure co-transmission. In the later stage, they are all adjusted to low-pressure operation and pressurized within the station to meet production requirements; this process is a dual-pressure system mixed gas gathering process optimized by combining the geological characteristics and economic efficiency of tight gas horizontal well development, which effectively reduces the diameter of the gas production pipeline, improves the matching degree of the pipeline to the pressure system and the adaptability of the process, and the choice of pressurization time is more economical and has stronger adaptability to subsequent development and construction.

[0033] Example 2

[0034] On the basis of Example 1, further, a meter is included, and the outlet of the medium-pressure separator and the outlet of the compressor are both connected to the meter. The meter is an existing meter, which can measure the gas volume, pressure, temperature and other parameters of the natural gas transmission of the gas gathering station to improve the measurement accuracy.

[0035] Furthermore, it also includes a pig, through which the medium-pressure station entry area unit is connected to the medium-pressure separator, and the low-pressure station entry area unit is connected to the low-pressure separator. The pig is an existing pig, and the pig is a pig equipped with an electric emergency shut-off valve, which can ensure the safety of the low-pressure station entry area unit, the gas gathering branch line and the station.

[0036] Furthermore, it also includes an alcohol injection device and a methanol tank, the outlet of the methanol tank is connected to the inlet of the alcohol injection device, and the outlet of the alcohol injection device is connected to the alcohol injection port of the medium-pressure gas production main. The methanol tank is an existing device that realizes the storage of methanol; the alcohol injection device is an existing device, and the alcohol injection device injects the methanol in the methanol tank into the alcohol injection pipeline through the alcohol injection pump to inject alcohol into the gas production pipeline of the medium-pressure inlet station area unit of the well site, realizing the centralized alcohol injection in the early stage, which is highly flexible.

[0037] Furthermore, a flash tank is also included, and the medium-pressure separator, low-pressure separator and compressor are all connected to the flash tank through a sewage pipeline. The flash tank is an existing device. The present invention uses a flash tank to flash the produced liquid, providing a space for vaporization and vapor-liquid separation of the fluid in the produced liquid, thereby improving production efficiency.

[0038] Furthermore, it also includes a venting device, wherein the medium-pressure station entry area unit, the medium-pressure separator, the low-pressure station entry area unit, the low-pressure separator, the compressor, the pig, the flash tank and the meter are all connected to the venting device through a venting pipeline. The venting device is an existing device, which realizes the processing of venting gas from the medium-pressure station entry area unit, the medium-pressure separator, the low-pressure separator, the low-pressure station entry area unit, the compressor, the pig and its pipelines in an emergency state, thereby improving safety.

[0039] Furthermore, it also includes a liquid separator device, wherein the medium-pressure station entry area unit, the medium-pressure separator, the low-pressure station entry area unit, the low-pressure separator, the compressor, the pipe cleaner, the flash tank and the meter are all connected to the inlet of the liquid separator device through a venting pipeline, and the gas outlet of the liquid separator device is connected to the venting device. The liquid separator device is an existing device, which realizes gas-liquid separation of the vented gas of each of the above devices to prevent fire rain during venting. The liquid separator device is provided with an electric ball valve to realize automatic liquid discharge, with a high degree of automation and strong operability.

[0040] Furthermore, it also includes a produced liquid storage tank, and the liquid outlets of the pipe cleaner, the liquid separator tank and the flash tank are all connected to the produced liquid storage tank through a sewage pipeline. The produced liquid storage tank is an existing device, which can realize the centralized collection and storage of sewage from the medium-pressure separator, the low-pressure separator, the liquid separator tank device and the venting device, thereby reducing environmental pollution; the produced liquid storage tank is provided with an alarm, which will alarm when the sewage exceeds the high liquid level of the sewage tank, thereby improving intelligence and safety.

[0041] Furthermore, it also includes a flame arrester device, and the methanol tank and the produced liquid storage tank are both connected to the flame arrester device. The flame arrester device is an existing device, and the flame arrester can prevent external flames from entering the methanol tank and the produced liquid storage tank containing flammable and explosive gases, thereby improving safety.

[0042] Furthermore, the medium-pressure gas production main, medium-pressure station entry unit, medium-pressure separator, low-pressure gas production main, low-pressure station entry unit, low-pressure separator, compressor, pig, alcohol injection device and methanol tank, venting device, produced liquid storage tank, flame arrester device, flash tank are all modularized. The modularization is compact, space-saving, easy to dismantle and move, and easy to move, which greatly reduces the workload and installation time on site. At the same time, the device can be added or removed as needed to improve work efficiency.

[0043] As described above, the dual-pressure system of the gas gathering station of the present invention comprises a medium-pressure gas gathering unit and a low-pressure gas gathering unit, and the medium-pressure gas gathering unit and the low-pressure gas gathering unit comprise a medium-pressure gas production main pipe, a medium-pressure station entry unit, a medium-pressure separator, a low-pressure gas production main pipe, a low-pressure station entry unit, a low-pressure separator, a compressor, a pipe cleaner, an alcohol injection device and a methanol tank, a venting device, a produced liquid storage tank, a flame arrester device, a flash tank, and a liquid separator. The above devices are respectively fixedly connected in the gas gathering station, and through the connection between each other, gas gathering, separation, compression, metering, pipe cleaning, external transmission, It has functions such as venting and liquid drainage. At the same time, it adopts the alcohol injection process in conjunction with the medium and low pressure mixed gas gathering process of double-pipe double-pressure gathering and transportation. Double-pipe double-pressure gas production outside the station and dual-pressure system gas gathering inside the station. Alcohol is injected centrally in the early stage and pressurized production is carried out in the later stage. The matching degree of the ground construction pressure system is higher, the timing of pressurization is more economical, the investment cost of ground construction is greatly reduced, the adaptability of ground system development is greatly improved, the production and operation cost and the energy consumption cost of system operation are reduced, and each area is easy to form modularization, which reduces the cost of single installation, reduces the occupation of arable land and damage to the ecological environment, and facilitates the overall maintenance of the system.

[0044] Embodiment 3:

[0045] like Figure 2-4 As shown, based on Example 2, a gas gathering method of a dual-pressure system of a gas gathering station is provided. In the early stage of gas gathering, a medium-pressure gas gathering unit is used to gather gas; in the middle stage of gas gathering, a medium-pressure gas gathering unit and a low-pressure gas gathering unit are used to gather gas together; in the late stage of gas gathering, a low-pressure gas gathering unit is used to gather gas;

[0046] The gas collection method of the medium-pressure gas collection unit is as follows: the incoming gas from the medium-pressure gas production main enters the medium-pressure station entry unit, and after the medium-pressure station entry unit and the pipeline are cleaned by a pig, the incoming gas enters the medium-pressure separator for gas-liquid separation, and the separated gas is measured by a meter and then transported to the next gas collection station or processing plant;

[0047] The gas gathering method of the low-pressure gas gathering unit is as follows: the incoming gas from the low-pressure gas production main enters the low-pressure station entry area unit, and after the low-pressure station entry area unit and pipeline are cleaned by the pig, the incoming gas enters the low-pressure separator for gas-liquid separation, and the separated gas is pressurized by the compressor, measured by the meter, and then transported to the next gas gathering station;

[0048] The medium-pressure station entry area unit, pig, medium-pressure separator, meter, low-pressure station entry area, low-pressure separator, compressor and flash tank are all connected to the separator tank through the venting pipeline. The venting gas is separated into gas and liquid through the separator tank, and the separated gas enters the venting device for venting;

[0049] The liquid separated by the medium-pressure separator, the liquid separated by the low-pressure separator and the discharge liquid of the compressor enter the flash tank for flash evaporation. The liquid after flash evaporation, the liquid in the pipe cleaner and the liquid separated by the liquid separator are transported to the produced liquid storage tank through the sewage pipeline for storage.

[0050] The gas gathering method of the dual-pressure system of the gas gathering station provided by the present invention adopts a medium-pressure gas gathering unit to gather gas in the early stage of gas gathering; adopts a medium-pressure gas gathering unit and a low-pressure gas gathering unit to gather gas together in the middle stage of gas gathering; and adopts a low-pressure gas gathering unit to gather gas in the late stage of gas gathering; a "dual-pipe dual-pressure" operation model is formed, that is, two gas production pipelines (a medium-pressure gas production main pipe and a low-pressure gas production main pipe) are laid from the well site to the station site, one large and one small, and the gas gathering station is considered to operate at medium and low pressure dual pressures, so that the pipe diameter and equipment specifications during construction can be reduced. When the initial pressure is high, medium pressure (medium-pressure gas gathering unit gas gathering) is used for operation, and alcohol is injected centrally in the station; in the middle stage, as the pressure of the connected wells decreases and the production of the newly connected wells , adjusted to medium and low pressure (medium pressure gas gathering unit gas gathering and low pressure gas gathering unit gas gathering) mixed operation, flexibly adjusted the pipeline series connection method to achieve medium and low pressure co-transmission, and later adjusted to low pressure operation, and pressurized in the station to meet production requirements; this process is a dual-pressure system mixed gas gathering process optimized in combination with the geological characteristics and economy of tight gas horizontal well development. It adopts alcohol injection technology in conjunction with double-pipe dual-pressure gathering and transportation, forming a mixed gas gathering process of "downhole throttling + early concentrated alcohol injection + later pressurized production", which effectively reduces the diameter of the gas production pipeline, improves the matching degree of the pipeline to the pressure system and the adaptability of the process, and the choice of pressurization time is more economical and has stronger adaptability to subsequent development and construction.

[0051] The gas gathering method of the dual-pressure system of the gas gathering station of the present invention adopts the medium and low pressure mixed gas gathering process of the alcohol injection process and the dual-pipe dual-pressure gathering and transportation, dual-pipe dual-pressure gas production outside the station, dual-pressure gas collection inside the station, concentrated alcohol injection in the early stage, and pressurized production in the later stage, which can realize the functions of gas gathering, separation, compression, metering, pipe cleaning, external transmission, venting, and liquid drainage. The ground construction pressure system has a higher matching degree, the timing of pressurization is more economical, the ground construction investment cost is greatly reduced, the adaptability of ground system development is greatly improved, the production and operation costs and the system operation energy consumption costs are reduced, each area is easy to form modularization, so that the single unit installation cost is reduced, the occupation of arable land and damage to the ecological environment is reduced, and the overall system maintenance is convenient.

[0052] Embodiment 4:

[0053] Based on Example 3, a gas gathering method of a dual-pressure system of a gas gathering station is provided. In the early stage of gas gathering, the inlet pressure of the gas from the medium-pressure gas production main is 3.6 MPa, and a medium-pressure gas gathering unit is used for gas gathering;

[0054] In the middle stage of gas gathering, the inlet pressure of the medium-pressure gas production main is 3.6MPa, and the inlet pressure of the low-pressure gas production main is 1.0MPa. The medium-pressure gas gathering unit and the low-pressure gas gathering unit are used to gather gas together. After the compressor pressurizes the incoming gas, the compressor outlet pressure is 3.6MPa.

[0055] In the later stage of gas gathering, the inlet pressure of the low-pressure gas production main is 1.0MPa. The low-pressure gas gathering unit is used to gather gas. After the compressor pressurizes the incoming gas, the compressor outlet pressure is 3.6MPa.

[0056] The invention centrally injects alcohol into the medium-pressure gas production main in the early stage and conducts pressurized production in the later stage. The matching degree of the ground construction pressure system is higher, the timing of pressurization is more economical, the ground construction investment cost is greatly reduced, the adaptability of ground system development is greatly improved, and the production operation cost and the system operation energy consumption cost are reduced.

[0057] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A gas gathering method for a dual pressure system of a gas gathering station, characterized in that: In the early stage of gas gathering, medium-pressure gas gathering units are used for gas gathering; in the middle stage of gas gathering, medium-pressure gas gathering units and low-pressure gas gathering units are used for gas gathering together; in the late stage of gas gathering, low-pressure gas gathering units are used for gas gathering; The dual-pressure system of the gas gathering station includes a medium-pressure gas gathering unit, a low-pressure gas gathering unit, a meter, a pig, a flash tank, a venting device and a liquid separator device; The medium-pressure gas collection unit comprises a medium-pressure gas collection main, a medium-pressure station entry unit and a medium-pressure separator, wherein the inlet of the medium-pressure station entry unit is connected to the gas inlet of the medium-pressure gas collection main, and the outlet of the medium-pressure station entry is connected to the inlet of the medium-pressure separator; The low-pressure gas collection unit comprises a low-pressure gas collection main, a low-pressure station entry unit, a low-pressure separator and a compressor. The inlet of the low-pressure station entry unit is connected to the gas inlet of the low-pressure gas collection main, the outlet of the low-pressure station entry unit is connected to the inlet of the low-pressure separator, and the gas outlet of the low-pressure separator is connected to the inlet of the compressor; the outlet of the medium-pressure separator and the outlet of the compressor are combined through the gas collection branch line for external transmission; The outlet of the medium-pressure separator and the outlet of the compressor are both connected with a meter; a pig is connected between the medium-pressure station entry area unit and the medium-pressure separator, and between the low-pressure station entry area unit and the low-pressure separator; the medium-pressure separator, the low-pressure separator and the compressor are all connected to the flash tank through a sewage pipeline; the medium-pressure station entry area unit, the medium-pressure separator, the low-pressure station entry area unit, the low-pressure separator, the compressor, the pig, the flash tank and the meter are all connected to the inlet of the liquid separation tank device through a venting pipeline, and the gas outlet of the liquid separation tank device is connected to the venting device; The gas collection method of the medium-pressure gas collection unit is as follows: the incoming gas from the medium-pressure gas production main enters the medium-pressure station entry unit, and after the medium-pressure station entry unit and the pipeline are cleaned by a pig, the incoming gas enters the medium-pressure separator for gas-liquid separation, and the separated gas is measured by a meter and then transported to the next gas collection station or processing plant; The gas gathering method of the low-pressure gas gathering unit is as follows: the incoming gas from the low-pressure gas production main enters the low-pressure station entry area unit, and after the low-pressure station entry area unit and pipeline are cleaned by the pig, the incoming gas enters the low-pressure separator for gas-liquid separation, and the separated gas is pressurized by the compressor, measured by the meter, and then transported to the next gas gathering station; The medium-pressure station entry unit, pig, medium-pressure separator, meter, low-pressure station entry unit, low-pressure separator, compressor and flash tank are all connected to the separator tank through the venting pipeline. The venting gas is separated into gas and liquid through the separator tank, and the separated gas enters the venting device for venting; The liquid separated by the medium-pressure separator, the liquid separated by the low-pressure separator and the discharge liquid of the compressor enter the flash tank for flash evaporation. The liquid after flash evaporation, the liquid in the pipe cleaner and the liquid separated by the liquid separator are transported to the produced liquid storage tank through the sewage pipeline for storage.

2. The gas gathering method of the dual pressure system of a gas gathering station according to claim 1, characterized in that: It also includes an alcohol injection device and a methanol tank, the outlet of the methanol tank is connected to the inlet of the alcohol injection device, and the outlet of the alcohol injection device is connected to the alcohol injection port of the medium-pressure gas production main.

3. The gas gathering method of the dual pressure system of a gas gathering station according to claim 2, characterized in that: It also includes a produced liquid storage tank, and the liquid outlets of the pipe cleaner, the liquid separator tank and the flash tank are all connected to the produced liquid storage tank through a sewage pipeline.

4. The gas gathering method of the dual pressure system of a gas gathering station according to claim 3, characterized in that: It also includes a flame arrester device, and the methanol tank and the produced liquid storage tank are both connected to the flame arrester device.

5. The gas gathering method of the dual pressure system of a gas gathering station according to claim 4, characterized in that: The medium-pressure gas production main, medium-pressure station entry area unit, medium-pressure separator, low-pressure gas production main, low-pressure station entry area unit, low-pressure separator, compressor, pipe cleaner, alcohol injection device and methanol tank, venting device, produced liquid storage tank, flame arrester device, and flash tank are all modularly configured.

6. The gas gathering method of the dual pressure system of a gas gathering station according to claim 1, characterized in that: The pipe cleaning device is a pipe cleaning device provided with an electric emergency shut-off valve.

7. The gas gathering method of the dual pressure system of a gas gathering station according to claim 1, characterized in that: The liquid separation tank device adopts a liquid separation tank device provided with an electric ball valve.

8. The gas gathering method of the dual pressure system of a gas gathering station as claimed in claim 3, characterized in that: The produced liquid storage tank is a produced liquid storage tank provided with an alarm.

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