Application of closed oil well oil gas production metering device

Abstract

The invention relates to the technical field of oil well oil and gas production equipment, in particular to application of a closed oil well oil and gas production metering device, which is characterized in that the closed oil well oil and gas production metering device is provided with a three-phase separator, a flowback liquid recovery tank, a crude oil tank and a gas combustion torch / gas collector, a gas control valve and a gas pressure regulating valve are arranged on the gas conveying pipeline, the gas pressure regulating valve is arranged between the gas control valve and the gas combustion torch / gas collector, a low-pressure connecting pipeline is further arranged, one end of the low-pressure connecting pipeline is connected into the gas conveying pipeline between the gas control valve and the gas pressure regulating valve, and the other end of the low-pressure connecting pipeline is communicated with a crude oil tank; the crude oil tank, the gas conveying pipeline, the gas control valve, the gas pressure regulating valve and the low-pressure connecting pipeline form a low-pressure subsystem, the amount of gas remaining in the low-pressure subsystem is adjusted by adjusting the pressure of the gas pressure regulating valve on the gas conveying pipeline, so that the crude oil tank is in a pressure maintaining state, and the system pressure is controlled within 2.5 Mpa.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of oil well oil and gas production equipment, in particular to a closed oil well oil and gas production metering device which is reasonable in structure, high in safety and low in cost, can effectively treat or recover associated gas generated in oil exploitation, and improves the safety and efficiency of on-site construction and reduces adverse effects on the environment. BACKGROUND

[0002] In the oil and gas production of an oil field, for those scattered, remote and early development oil wells, especially newly developed shale oil wells, due to the lack of conditions for large-scale centralized production, a small-scale independent oil and gas production system is often used, taking a single well or several wells as a unit. In this oil well oil and gas production system, the oil-water-gas multiphase flow output from the oil well is input into a three-phase separator through a pipeline and a choke manifold of the oil well. The three-phase separator can adopt the oil-water-gas multiphase flow array type measuring device described in the patent document CN115506775A. The three-phase separator is connected with a gas burner or a gas receiving tank, a crude oil recovery tank and a flowback fluid recovery tank through a gas pipeline, an oil pipeline and a water pipeline respectively. A gas control valve, a crude oil control valve and a free water control valve are respectively arranged on the gas pipeline, the oil pipeline and the water pipeline. The associated gas separated from the three-phase separator is transported to the gas burner for combustion to prevent environmental damage, or is sent to the gas receiving tank for storage. The crude oil separated from the three-phase separator contains a small amount of water and is transported to the crude oil recovery tank for storage before being transported. The free water separated from the three-phase separator is transported to the flowback fluid recovery tank for storage before being transported.

[0003] Due to the functions of liquid inlet and outlet at any time and the convenience of grasping the distribution of liquid in the tank, and considering the technology, cost and convenience, the existing crude oil recovery tank and flowback fluid recovery tank are connected with the atmosphere through a breather valve or an observation hole and work in a most of the time under normal pressure. Under the normal working condition of the three-phase separator, the liquid in the flowback fluid recovery tank is basically free water, and this working mode has no problem. However, the crude oil recovery tank exchanges associated gas represented by methane with the atmosphere, and the crude oil in the crude oil recovery tank continuously releases new associated gas during heating. In addition to the problem of not being able to grasp the stratified distribution of oil and water in the tank in real time, there are two other problems that cannot be ignored: one is the pollution and damage of methane and other gases to the environment, and the other is the safety problem caused thereby. With the increase of the number of oil wells in production, these two problems are increasingly serious and cannot be ignored. SUMMARY

[0004] The application aims at the shortcomings and deficiencies in the prior art, and provides an application of a closed oil well oil and gas production metering device which is reasonable in structure, high in safety and low in cost, can effectively treat or recover associated gas generated in oil liquid exploitation, and thus improves the safety and efficiency of on-site oil and gas production and reduces adverse effects on the environment.

[0005] The application achieves the above-mentioned purposes by the following measures:

[0006] The application of a closed oil well oil and gas production metering device is characterized in that the closed oil well oil and gas production metering device is provided with a three-phase separator, a flowback fluid recovery tank, a crude oil tank and a gas combustion torch / gas collector, the oil-water-gas multiphase flow output from the oil well is input into the three-phase separator through a pipeline, the three-phase separator is connected with the gas combustion torch / gas collector through a gas conveying pipeline and connected with the crude oil tank through an oil conveying pipeline, and the three-phase separator is connected with the flowback fluid recovery tank through a water conveying pipeline, wherein the crude oil tank is a closed pressure container, a gas control valve and a gas pressure regulating valve are arranged on the gas conveying pipeline, the gas pressure regulating valve is arranged between the gas control valve and the gas combustion torch / gas collector, and a low-pressure connecting pipeline is further arranged, one end of the low-pressure connecting pipeline is connected to the gas conveying pipeline between the gas control valve and the gas pressure regulating valve, and the other end is connected with the crude oil tank in communication.

[0007] The crude oil tank, the gas conveying pipeline, the gas control valve, the gas pressure regulating valve and the low-pressure connecting pipeline form a low-pressure subsystem, the low-pressure subsystem is connected with an external gas boiler and / or a gas generator through a gas pipeline, the pressure of the gas pressure regulating valve on the gas conveying pipeline is adjusted to adjust the gas retention amount in the container and the pipeline in the low-pressure subsystem, the crude oil tank is kept in a pressure maintaining state during operation, the system pressure is controlled to be less than 2.5 MPa, and the balance between the cost, technology and performance of the system equipment is maintained.

[0008] A gas switch valve is arranged on the low-pressure connecting pipeline.

[0009] The flowback fluid recovery tank is a normal pressure container or a closed pressure container, a bottom water pipeline is arranged between the bottom of the crude oil tank and the flowback fluid recovery tank, a bottom water pipeline valve is arranged on the bottom water pipeline, and a bottom water pump can be further arranged, further, an oil accumulation pipeline is arranged between the middle or upper part of the flowback fluid recovery tank and the crude oil tank, an oil pump and an oil accumulation valve are arranged on the oil accumulation pipeline, and the oil accumulation pipeline is used to discharge the oil accumulated in the upper part of the flowback fluid recovery tank into the crude oil tank under the assistance of an oil and water distribution array sensor.

[0010] The upper part of the crude oil tank is provided with a gas pipeline between the upper part of the flowback fluid recovery tank, and a gas valve is arranged on the gas pipeline, so that the crude oil tank can realize normal pressure operation under the working conditions such as maintenance.

[0011] The crude oil control valve is arranged on the oil pipeline, and the free water control valve is arranged on the water pipeline, so as to realize the adjustment and control of the oil pipeline and the water pipeline connected with the three-phase separator respectively.

[0012] The segmented oil-water analysis and measurement array is arranged on the crude oil tank, so as to monitor the oil-water distribution condition of the crude oil recovery tank, and real-time master the oil-water interface, total liquid level, water content of each stratified crude oil, overall water content of the crude oil in the tank, total amount of the crude oil in the tank and other parameters in the crude oil recovery tank, so as to realize fine management of oil and gas production; the water content of the crude oil at the horizontal position opposite to the crude oil outlet in the crude oil tank can also be monitored through the segmented oil-water analysis and measurement array, so as to participate in the control of the crude oil.

[0013] The segmented oil-water analysis and measurement array can also be arranged on the flowback fluid recovery tank, so as to monitor the oil-water interface and total liquid level in the flowback fluid recovery tank, so as to facilitate the exclusion of the accumulated oil layer or the monitoring of the water content at the horizontal position opposite to the liquid outlet in the flowback fluid recovery tank.

[0014] In the application, the liquid flow meter and the automatic control valve connected therewith can be arranged on the external pipeline of the crude oil tank or the flowback fluid recovery tank, the liquid flow meter and the automatic control valve connected therewith are combined with the water content of the crude oil at the crude oil outlet, so as to realize fine and substantial control of the amount of the crude oil to be transported; when the crude oil tank or the flowback fluid recovery tank is emptied, the reading of the liquid flow meter will abnormally change, and accordingly the automatic control valve can be controlled to be closed in time, so as to realize automatic loading.

[0015] In the application, the oil-water-gas multiphase flow produced by the oil well is adjusted through the choke manifold, and then input to the three-phase separator through the pipeline, so that the associated gas, emulsified oil and free water are separated in the three-phase separator; the associated gas is transported to the gas burner / collection device through the gas pipeline, the gas control valve and the gas pressure regulating valve, and is collected by the collection device or burned by the gas burner, so that the pollution and safety hazards of the associated gas are eliminated.

[0016] In the present application, the emulsified oil is delivered to the crude oil tank through the oil delivery pipeline and the crude oil control valve. The crude oil tank is a closed pressure tank which is communicated with the gas delivery pipeline between the gas control valve and the gas pressure regulating valve. When the input crude oil in the crude oil tank occupies the space or the heating causes part of the crude oil to be gasified, resulting in the pressure being greater than the setting pressure of the gas pressure regulating valve, the gas in the tank will be delivered back to the gas burner or the collector through the gas pipeline for disposal, thereby ensuring the production process and eliminating the escape of associated gas. The separated free water is delivered to the flowback fluid recovery tank through the water delivery pipeline and the free water control valve. Since the free water will not produce associated gas, even if the flowback fluid recovery tank is an atmospheric tank which can communicate with the atmosphere, there will be no safety hazards or gas pollution.

[0017] In the above oil well oil and gas production metering system, the gas delivery pipeline between the gas control valve and the gas pressure regulating valve, the gas pipeline and the closed crude oil tank jointly constitute a low-pressure subsystem with dynamic stability of gas and pressure. The system can not only take full advantage of the empty volume of the closed crude oil tank to play the role of gas buffer, but also can play the role of supplement or absorption of associated gas by the gas delivery pipeline. By adjusting the setting parameters of the gas pressure regulating valve, the pressure in the subsystem can be determined. The buffer capacity of the entire low-pressure subsystem can be increased or decreased as needed, thereby providing a high-reliability and good-compatibility basic support system for the optimization of the field process and the stable operation of the equipment.

[0018] With the above low-pressure subsystem, when a large amount of associated gas is generated in the crude oil tank due to phase change caused by heating, injection of crude oil, etc., the excess associated gas will be delivered to the gas burner or the collector through the low-pressure subsystem. When the pressure of the crude oil tank decreases due to reasons such as the output of crude oil and the discharge of bottom water, the low-pressure subsystem will automatically maintain its stability.

[0019] Compared with the prior art, the present application has the following advantages: (1) The closed operation of the main oil well oil and gas production devices and processes is realized, and the running, escaping and leaking of the oil well production associated gas represented by methane is systematically eliminated, thereby ensuring the safety and environmental protection of oil well oil and gas production. (2) The production process is reasonable and simple, the automation and informatization level is high, and the cost performance is high. The main index parameters of the field production metering process, such as the total crude oil and the stratified water cut distribution, the three-phase separation effect, and the water cut of the output crude oil, are substantially and real-timely monitored, thereby meeting the requirements of large-scale and intensive oilfield production. (3) The low-pressure subsystem not only provides a high-capacity and stable buffer power source for the output liquid and process control, but also provides a stable gas source for the power system such as the gas boiler and the gas generator on site, thereby fully utilizing the abandoned resources and increasing the income and reducing the expenditure. (4) The output of the crude oil is stable and the guarantee degree is high, and the output process is safe and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0020] Appendix Figure 1 This is a schematic diagram of a structure of the present invention, wherein the crude oil tank is a closed pressure vessel. (Attached) Figure 2 This is a schematic diagram showing the connection between the crude oil tank, which uses a closed pressure vessel, and the atmospheric pressure return fluid recovery tank in this invention.

[0021] Appendix Figure 3 This is a schematic diagram of one embodiment of the present invention.

[0022] Appendix Figure 4 This is a schematic diagram of another embodiment of the present invention.

[0023] Appendix Figure 5 This is a schematic diagram of the structure of the crude oil tank and the backflow recovery tank in this invention, both of which are enclosed pressure vessels.

[0024] Appendix Figure 6 This is a schematic diagram of an oil-water analysis array with a segmented structure in an embodiment of the present invention.

[0025] Figure reference numerals: Oil well 1, Wellhead manifold 2, Three-phase separator 3, Water pipeline 34, Free water control valve 341, Oil pipeline 35, Crude oil control valve 351, Gas pipeline 36, Gas control valve 361, Gas pressure regulating valve 362, Flame arrestor 363, Low-pressure connection pipeline 365, Gas switch valve 3651, Drainage fluid recovery tank 4, Drainage fluid export pipeline 401, Drainage fluid export valve 4011, Liquid flow meter 4012, Drainage pump 4013, Segmented oil-water analysis measurement array on the drainage fluid recovery tank 41, Gas breather valve 42, Gas pipeline 45 2. Gas valve 4521, oil collection pipeline 453, oil pump 4531, oil collection valve 4532, crude oil tank 5, crude oil export pipeline 501, crude oil export valve 5011, crude oil export liquid flow meter 5012, oil discharge pump 5013, self-use gas connection pipeline 502, gas boiler 5021, gas generator 5022, segmented oil-water analysis and measurement array on crude oil tank 51, sister tank group consisting of crude oil tank and atmospheric pressure backflow tank 54, bottom water pipeline 541, bottom water pipeline valve 5411, bottom water pump 5412, gas combustion flare / gas collector 6. Detailed implementation method:

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] As attached Figure 1 and appendix Figure 2As shown, the application proposes a closed oil well oil and gas production metering device, which is provided with a three-phase separator 3, a flowback liquid recovery tank 4, a crude oil tank 5, a gas combustion torch / gas collector 6, and the oil-water-gas multiphase flow output from the oil well 1 is input to the three-phase separator 3 through the pipeline, the three-phase separator 3 is connected with the gas burner or the gas collector 6 through the gas pipeline 36, is connected with the crude oil tank 5 through the oil pipeline 35, and the three-phase separator 3 is connected with the flowback liquid recovery tank 4 through the water pipeline 34, wherein the crude oil tank 5 is a closed pressure container, the gas control valve 361 and the gas pressure regulating valve 362 are arranged on the gas pipeline 36, the gas pressure regulating valve 362 is arranged between the gas control valve 361 and the gas combustion torch / gas collector 6, and a low-pressure connecting pipeline 365 is further arranged, one end of the low-pressure connecting pipeline 365 is connected to the gas pipeline 36 between the gas control valve 361 and the gas pressure regulating valve 362, and the other end is connected with the crude oil tank 5 in communication.

[0028] The crude oil tank 5, the gas pipeline 36, the gas control valve 361, the gas pressure regulating valve 362 and the low-pressure connecting pipeline 365 of the application form a low-pressure subsystem, by adjusting the pressure of the gas pressure regulating valve 362 on the gas pipeline 36, the amount of gas remaining in the container and pipeline in the low-pressure subsystem is adjusted, so that the crude oil tank 5 is in a pressure maintaining state during operation, which is beneficial to the output of crude oil and the removal of residual water in the crude oil tank; further, the low-pressure subsystem is connected with the external gas boiler 5021 or / and gas generator 5022 through the gas pipeline.

[0029] In order to increase the gas buffer capacity of the low-pressure subsystem, a separately closed gas pressure buffer tank can also be connected therein or a plurality of closed crude oil tanks 5 can be connected in parallel.

[0030] The low-pressure connecting pipeline 365 of the application is provided with a gas switch valve 3651.

[0031] The flowback liquid recovery tank 4 of the application adopts a normal pressure container or a closed pressure container, a bottom water pipeline 541 is arranged between the bottom of the crude oil tank 5 and the flowback liquid recovery tank 4, a bottom water pipeline valve 5411 is arranged on the bottom water pipeline 541, and a bottom water pump 5412 can be further arranged, further, an oil accumulation pipeline 453 is arranged between the middle or upper part of the flowback liquid recovery tank 4 and the crude oil tank 5, an oil pump 4531 and an oil accumulation valve 4532 are arranged on the oil accumulation pipeline 453, and the oil accumulation pipeline 453 is used to discharge the oil accumulated in the upper part of the flowback liquid recovery tank into the crude oil tank under the assistance of the oil-water distribution array sensor.

[0032] A gas pipeline 452 is arranged between the upper part of the crude oil tank 5 and the upper part of the flowback liquid recovery tank 4, and a gas valve 4521 is arranged on the gas pipeline 452, which is used to enable the crude oil tank 5 to realize normal pressure operation under the working condition of maintenance and the like.

[0033] The crude oil control valve 351 is arranged on the oil pipeline 35, the free water control valve 341 is arranged on the water pipeline 34, and the gas control valve 361 is arranged on the gas pipeline 36, which can be regarded as a part of the three-phase separator, and is used for adjusting and controlling the oil pipeline, the water pipeline and the gas pipeline connected with the three-phase separator 3.

[0034] The crude oil tank 5 is provided with a segmented oil-water analysis and measurement array, which is used for monitoring the oil-water distribution of the crude oil recovery tank, and is used for monitoring the oil-water interface, the total liquid level, the water content of each layer of crude oil, the overall water content of the crude oil in the tank, the total amount of the crude oil in the tank and the like in the crude oil recovery tank in real time, so that the fine management of oil and gas production is realized; the segmented oil-water analysis and measurement array can also be used for monitoring the water content of the crude oil at the position vertically opposite to the crude oil outlet in the crude oil tank, so as to participate in the control of the crude oil.

[0035] The segmented oil-water analysis and measurement array can also be used for monitoring the oil-water interface and the total liquid level in the produced fluid recovery tank, so as to facilitate the removal of the oil accumulation layer in the produced fluid recovery tank or the monitoring of the water content at the position vertically opposite to the liquid outlet in the produced fluid recovery tank.

[0036] In the present application, the liquid flow meter and the automatic control valve connected therewith can be arranged on the external pipeline of the crude oil tank 5 or the produced fluid recovery tank 4, and the liquid flow meter and the automatic control valve connected therewith are combined with the water content of the crude oil at the crude oil outlet, so that the fine and substantial control of the amount of the crude oil to be transported out can be realized; when the crude oil tank or the produced fluid recovery tank is emptied, the liquid flow meter will abnormally change, and accordingly the automatic control valve can be controlled to be closed in time, so that the automatic loading can be realized.

[0037] In the present application, the oil-water-gas multiphase flow produced by the oil well 1 is adjusted by the oil well choke manifold 2, is input into the three-phase separator 3 through the pipeline 23, and is subjected to controllable separation of associated gas, emulsified oil and free water in the three-phase separator; then, the associated gas is transported to the gas burner / collection device 6 through the gas pipeline 36, the gas control valve 361 and the gas pressure regulating valve 362, is collected by the collection device 6 or is burned by the gas burner, so that the pollution and the safety hazard of the associated gas are eliminated.

[0038] The emulsified oil is transported to the crude oil tank 5 through the oil pipeline 35 and the crude oil control valve 35. Since the crude oil tank 5 is a closed pressure tank communicated with the gas pipeline 36 between the gas control valve 361 and the gas pressure regulating valve 362 through the gas pipeline 365, when the input crude oil in the crude oil tank 5 is full or heated to make part of the crude oil gasified, resulting in a pressure greater than the setting pressure of the gas pressure regulating valve 362, the gas in the tank will be returned to the gas burner or collector 6 through the gas pipeline 365 and the gas pipeline 36 for treatment, which not only ensures the production process, but also eliminates the escape of associated gas;

[0039] The separated free water is transported to the flowback fluid recovery tank 4 through the water pipeline 34 and the free water control valve 341. Since the free water will not produce associated gas, even if the flowback fluid recovery tank 4 is an atmospheric tank that can communicate with the atmosphere, there will be no safety hazards or gas pollution. The zero emission of associated gas such as methane into the air is achieved.

[0040] In the above oil and gas production metering system, the gas pipeline 36 between the gas control valve 361 and the gas pressure regulating valve 362, the gas pipeline 365 and the closed crude oil tank 5 jointly form a low-pressure subsystem with dynamic stability of gas and pressure. This system can not only take full advantage of the empty volume of the closed crude oil tank to play the role of gas buffer, but also can play the role of supplement or absorption of associated gas through the gas pipeline 36. By adjusting the setting parameters of the gas pressure regulating valve 362, the pressure in this subsystem can be determined. The buffer capacity of the entire low-pressure subsystem can be increased or decreased as needed, which provides a reliable and compatible basic support system for the optimization of the field process and the stable operation of the equipment. Considering the factors of technology, cost and demand, the pressure can be controlled between 0 and 2.5 MPa in the field application. With the help of the low-pressure subsystem, when a large amount of associated gas is generated in the crude oil tank 5 due to phase change caused by heating, injection of crude oil, etc., the excess associated gas will be transported to the gas burner or collector 6 through the low-pressure subsystem. When the pressure of the crude oil tank 5 decreases due to the reasons such as export of crude oil and drainage of bottom water, the low-pressure subsystem will automatically maintain its stability.

[0041] Example 1:

[0042] This example proposes a closed oil and gas production metering device as shown in Figure 1 , 2 In this example, the crude oil tank 5 is a closed pressure vessel, and the flowback fluid recovery tank 4 is an atmospheric tank. Figure 2As shown, the top of the flowback fluid recovery tank 4 is provided with a gas breather valve 42. In this example, a middle or upper portion of the flowback fluid recovery tank 4 is further provided with an oil accumulation pipeline 453, which is provided with an oil pump 4531 and an oil accumulation valve 4532, for assisting the oil-water distribution array sensor to discharge the oil accumulated in the upper portion of the flowback fluid recovery tank 4 into the crude oil tank. To achieve this function, the flowback fluid recovery tank 4 and the crude oil tank 5 are respectively provided with oil-water analysis and measurement arrays;

[0043] This example utilizes the segmented oil-water analysis and measurement array structure and measurement principle described in the previously proposed invention patent 201280001767.5, which can not only measure the water content of the oil-water mixture layer by layer, but also accurately determine the height of the total liquid level and the oil-water interface. The integrated oil-water interface and liquid level measurement assembly of the above segmented oil-water analysis function can use, for example, a commercial multiphase oil-water interface instrument with model number HDW-121.

[0044] Embodiment 2:

[0045] As shown in the accompanying Figure 3 and the accompanying Figure 4 As shown, a closed oil well oil and gas production metering device is provided, which is provided with a three-phase separator 3, a flowback fluid recovery tank 4, a crude oil tank 5, and a gas combustion torch / gas collector 6. The oil-water-gas multiphase flow output from the oil well 1 is input to the three-phase separator 3 through a pipeline. The three-phase separator 3 is connected to the gas combustion torch / gas collector 6 through a gas conveying pipeline 36, connected to the crude oil tank 5 through an oil conveying pipeline 35, and connected to the flowback fluid recovery tank 4 through a water conveying pipeline 34. The crude oil tank 5 is a closed pressure vessel. The gas conveying pipeline 36 is provided with a gas control valve 361 and a gas pressure regulating valve 362. The gas pressure regulating valve 362 is arranged between the gas control valve 361 and the gas combustion torch / gas collector 6. A low-pressure connection pipeline 365 is also provided, which is connected to the gas conveying pipeline 36 between the gas control valve 361 and the gas pressure regulating valve 362 at one end and connected to the crude oil tank 5 at the other end.

[0046] The crude oil tank 5, the gas conveying pipeline 36, the gas control valve 361, the gas pressure regulating valve 362, and the low-pressure connection pipeline 365 form a low-pressure subsystem. By adjusting the pressure of the gas pressure regulating valve 362 on the gas conveying pipeline 36, the amount of gas remaining in the container and pipeline of the low-pressure subsystem is adjusted, so that the crude oil tank 5 is in a pressure maintaining state during operation, which is conducive to the output of crude oil and the removal of residual water in the crude oil tank. The low-pressure subsystem described in this example is connected to an external gas boiler 5021 or / and a gas generator 5022 through a gas pipeline.

[0047] In order to improve the system operation safety, the fire damper 363 is arranged behind the gas pressure regulating valve 362 of the gas pipeline 36.

[0048] In the example, the sister tank group 54 is composed of the crude oil tank 5 and the flowback fluid recovery tank 4, the bottom water pipeline 541 is arranged between the bottom of the crude oil tank 5 and the flowback fluid recovery tank 4, the bottom water pipeline valve 5411 or the bottom water pump 5412 is arranged on the bottom water pipeline 541, the gas pipeline 452 is arranged at the top of the two tanks, and the gas valve 4521 is arranged on the gas pipeline 452; during use, as long as the gas valve 4521 on the gas pipeline 452 at the top of the two tanks is opened and the gas circuit is kept in communication, the closed operation of the tank group is realized.

[0049] During the oil-water separation and stabilization in the tank before the external transportation, if the bottom water in the crude oil tank 5 accumulates to a sufficient height, the segmented oil-water analysis and measurement array 51 can accurately and timely inform the opening of the bottom water valve 5411 or the bottom water pump 5412, and the bottom water is discharged into the flowback fluid recovery tank 4 through the bottom water pipeline 541.

[0050] During the external transportation of the crude oil, the real-time water content of the crude oil measured by the segmented oil-water analysis and measurement array 51 at the level of the crude oil external transportation port and below is used to predict the over-standard trend of the crude oil in the tank, to reduce the oil-water interface and the height of the standard crude oil by discharging the bottom water, and to ensure the stable and standard external transportation of the crude oil; the water content measured by the measurement unit at the level of the crude oil external transportation port is combined with the data measured by the crude oil external transportation valve 5011 and the liquid flowmeter 5012 installed on the crude oil external transportation pipeline 501, and the net value and other production parameters of the external transportation crude oil can be conveniently obtained.

[0051] Compared with the prior art, the present application has the following advantages: (1) the closed operation of the main oil and gas production device and process of the oil well is realized, the running, escaping and leaking of the oil well production associated gas represented by methane are systematically eliminated, and the safety and environmental protection of the oil well oil and gas production are ensured. (2) The production process is reasonable and simple, the automation and informatization level and the cost performance are high, the real-time monitoring of the main index parameters such as the water content distribution of the oil layer, the three-phase separation effect and the water content of the external transportation crude oil is realized, and the requirements of the oil field production scale and intensification are met. (3) The low-pressure subsystem not only provides a high-capacity and stable buffer power source for the external transportation liquid and the process control, but also provides a stable gas source for the power system such as the gas boiler and the gas generator on the site, the abandoned resources can be fully utilized, and the income and expenditure can be increased and saved. (4) The stability and standard guarantee degree of the external transportation crude oil is high, and the external transportation process is safe and reliable.

Claims

1. Use of a closed oil and gas production metering device for an oil well, characterized in that The closed oil well oil and gas production metering device is provided with a three-phase separator, a flowback liquid recovery tank, a crude oil tank and a gas combustion torch / gas collector. The oil-water-gas multiphase flow output from the oil well is input to the three-phase separator through a pipeline. The three-phase separator is connected with the gas burner or the gas collector through a gas pipeline, and is connected with the crude oil tank through an oil pipeline. The three-phase separator is connected with the flowback liquid recovery tank through a water pipeline. The crude oil tank is a closed pressure container. A gas control valve and a gas pressure regulating valve are arranged on the gas pipeline. The gas pressure regulating valve is arranged between the gas control valve and the gas combustion torch / gas collector. A low-pressure connecting pipeline is further arranged. One end of the low-pressure connecting pipeline is connected to the gas pipeline between the gas control valve and the gas pressure regulating valve, and the other end is connected with the crude oil tank in communication. The crude oil tank, the gas pipeline, the gas control valve, the gas pressure regulating valve and the low-pressure connecting pipeline form a low-pressure subsystem. The gas retention amount in the containers and pipelines in the low-pressure subsystem is adjusted by adjusting the pressure of the gas pressure regulating valve on the gas pipeline, so that the crude oil tank is in a pressure maintaining state during operation, the system pressure is controlled within 2.5 MPa, and the balance between the cost, technology and performance of the system equipment is maintained.

2. The closed oil well production metering device of claim 1, wherein, The low-pressure subsystem is connected with an external gas boiler or / and a gas generator through a gas pipeline.

3. The closed oil well production metering device of claim 1, wherein, A gas switch valve is arranged on the low-pressure connecting pipeline.

4. The closed oil well production metering device of claim 1, wherein, The flowback liquid recovery tank is a normal pressure container or a closed pressure container. A bottom water pipeline is arranged between the bottom of the crude oil tank and the flowback liquid recovery tank. A bottom water pipeline valve is arranged on the bottom water pipeline. When the flowback liquid recovery tank is a closed pressure container, a bottom water pump is further arranged on the bottom water pipeline.

5. The closed oil well production metering device of claim 1, wherein, An oil accumulation pipeline is further arranged between the middle or upper part of the flowback liquid recovery tank and the crude oil tank. An oil pump and an oil accumulation valve are arranged on the oil accumulation pipeline, which are used to discharge the oil accumulated in the upper part of the flowback liquid recovery tank into the crude oil tank under the assistance of the oil-water distribution array sensor.

6. The closed oil well production metering device of claim 1, wherein, A gas pipeline is arranged between the upper part of the crude oil tank and the upper part of the flowback liquid recovery tank, and a gas valve is arranged on the gas pipeline, which is used to enable the crude oil tank to operate at normal pressure in a maintenance condition.

7. The closed oil well production metering device of claim 1, wherein, A crude oil control valve is arranged on the oil pipeline, and a free water control valve is arranged on the water pipeline, which are used to respectively adjust and control the oil pipeline and the water pipeline connected with the three-phase separator.

8. The closed oil well production metering device of claim 1, wherein, The crude oil tank and the flowback liquid recovery tank are provided with a segmented oil-water analysis measurement array or a segmented oil-water analysis measurement array, which are used to monitor the oil-water distribution condition in the crude oil recovery tank or the flowback liquid recovery tank. The oil-water analysis measurement array or the segmented oil-water analysis measurement array is also used to monitor the water content of the crude oil at the position directly opposite to the crude oil outlet of the crude oil tank or the water content at the position directly opposite to the liquid outlet of the flowback liquid recovery tank.

9. The closed oil well production metering device of claim 1, wherein, A liquid flowmeter and an automatic control valve are arranged on the liquid outlet pipeline of the crude oil tank or the flowback liquid recovery tank.

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