Three-phase flow on-line metering system applied to single-well oil pipeline

Abstract

The three-phase flow on-line metering system is provided with an oil inlet pipe, an outlet of the oil inlet pipe is connected with a gas-liquid separation pipe, the lower end of the gas-liquid separation pipe is connected with a transversely-arranged liquid pipe section, the upper end of the gas-liquid separation pipe is connected with an inlet of a gas pipe section, and the gas pipe section is connected with an outlet of the oil inlet pipe. An outlet of the gas pipe section is connected with the liquid pipe section, a vortex shedding flowmeter is installed on the gas pipe section, and an oil-water analyzer, a radar liquid level meter and an impeller velocimeter are installed on the portion, between the gas-liquid separation pipe and the outlet of the gas pipe section, of the liquid pipe section. And the vortex shedding flowmeter, the oil-water analyzer, the radar liquid level meter and the impeller velocimeter are connected with the controller. The three-phase flow meter can be installed on a single-well oil conveying pipeline, on-line automatic metering of three-phase flow is achieved, and the real yield of an oil well is accurately metered. Manual intervention is not needed, the labor intensity and the labor cost of metering personnel are reduced, meanwhile, the investment of ground engineering can be greatly saved, and therefore the economic benefits of enterprises are improved.

Description

Technical Field

[0001] The utility model relates to an oil metering device, in particular to a three-phase flow online metering system for a single-well oil transmission pipeline. Background Art

[0002] In the process of oil production, it is necessary to measure the output of natural gas and crude oil from a single well. Since water is usually injected into the oil production layer during oil extraction to supplement the missing energy in the underground oil well or reduce the viscosity of the crude oil, the oil transmission pipeline of the fluid produced by the beam pumping unit contains three-phase media of oil, water and gas, and the flow form is slug flow (wavy flow), that is, the liquid does not completely fill the pipeline. Therefore, any existing flowmeter cannot perform online flow detection on the three-phase flow in the oil transmission pipeline. For this reason, the previous metering method was to transport the gas-liquid produced by a single well through a pipeline to a metering room for volumetric measurement (separator metering and tipping bucket metering tank) with a period of one hour, and then calculate the total amount of natural gas and oil liquid in 24 hours of the whole day; the water content was determined by the method of manual on-site wellhead sampling and testing (distillation method, etc.). The difference between the total amount of oil liquid and the water content was the daily crude oil output of a single well. The following problems exist:

[0003] The output of each oil well is only measured for one hour. For oil wells with normal liquid supply, the error of this metering method is about 10%, while for oil wells with fluctuating liquid supply, the error even reaches 40%, and the metering accuracy is relatively low;

[0004] 2. Manual wellhead sampling and testing not only have a large labor intensity for sampling personnel, waste crude oil (samples), and are time-consuming and laborious, but also have poor representativeness because the sampling volume is only a part of the fluid and is very small compared with the liquid production of the oil well; especially under special weather conditions, manual sampling and water content detection cannot be carried out on site, which directly affects the metering of crude oil.

[0005] In order to overcome the problems existing in the previous water content detection method, the Chinese utility model patent with the patent number 202122651099.X discloses an "online intelligent monitor for wireless transmission of petroleum water content", which can accurately monitor the water content of petroleum online, eliminate the need for personnel to collect samples at the wellhead, reduce crude oil waste and save manpower, but still cannot perform online metering on the three-phase flow in the oil transmission pipeline. Summary of the Invention

[0006] The utility model is to solve the above technical problems existing in the prior art, and provides a three-phase flow online metering system applied to a single-well oil transmission pipeline.

[0007] The technical solution of the utility model is: a three-phase flow on-line metering system applied to a single-well oil pipeline, which is provided with an inlet oil pipe, the outlet of the inlet oil pipe is connected to a gas-liquid separation pipe, the lower end of the gas-liquid separation pipe is connected to a horizontally arranged liquid pipe section, the upper end of the gas-liquid separation pipe is connected to the inlet of a gas pipe section, the outlet of the gas pipe section is connected to the liquid pipe section, a vortex flowmeter is installed on the gas pipe section, an oil-water analyzer, a radar level gauge and an impeller speedometer are installed on the liquid pipe section between the gas-liquid separation pipe and the outlet of the gas pipe section, and the vortex flowmeter, the oil-water analyzer, the radar level gauge and the impeller speedometer are connected to a controller.

[0008] Preferably, a floating ball is arranged inside the gas-liquid separation pipe, and thorns are arranged on the surface of the floating ball.

[0009] The utility model can be installed on a single-well oil pipeline to realize on-line automatic metering of three-phase flow (oil, water, gas), accurately measure the true output of an oil well; without manual intervention, reduce the labor intensity and labor cost of metering personnel, and at the same time can greatly save the investment in ground engineering (metering room connecting pipelines and equipment, etc.), thereby improving the economic benefits of the enterprise. Brief Description of the Drawings

[0010] Figure 1 is a schematic structural diagram of an embodiment of the utility model.

[0011] Figure 2 is a schematic circuit principle block diagram of an embodiment of the utility model.

[0012] Figure 3 is a schematic structural diagram of the floating ball in an embodiment of the utility model.

[0013] Figure 4 is a schematic diagram of the liquid level height in the pipeline measured by the radar level gauge in an embodiment of the utility model. Detailed Description of the Preferred Embodiment

[0014] A three-phase flow on-line metering system applied to a single-well oil pipeline according to the utility model is as Figure 1 、 2As shown in the figure, there is an oil inlet pipe 1. The outlet of the oil inlet pipe 1 is connected to the middle of the vertical gas-liquid separation pipe 2 through a flange. The lower end of the gas-liquid separation pipe 2 is connected to the horizontally arranged liquid pipe section 3. The upper end of the gas-liquid separation pipe 2 is connected to the inlet of the gas pipe section 4. The outlet of the gas pipe section 4 is connected to the liquid pipe section 3. A vortex flowmeter 5 is installed on the gas pipe section 4. An oil-water analyzer 6, a radar level gauge 7 and an impeller speedometer 8 are installed on the liquid pipe section 3 between the outlet of the gas-liquid separation pipe 2 and the gas pipe section 4. The vortex flowmeter 5, the oil-water analyzer 6, the radar level gauge 7 and the impeller speedometer 8 are connected to a controller 9. The vortex flowmeter 5 is used to measure the gas flow in the pipeline; the oil-water analyzer 6 can adopt an "online intelligent monitor for wireless transmission of petroleum water content", that is, an analyzer based on microwave energy level variable technology, which is used to online monitor the change of the water content of crude oil in the pipeline; the radar level gauge 7 is a device for monitoring the liquid level height in the pipeline; the impeller speedometer 8 is used to output the number of pulses generated when the liquid flows through in a certain period of time; the controller 9 can be a PLC, etc., which is used for data acquisition, calculation, etc. A digital display and transmission unit can be connected to the controller 9. A floating ball 10 is placed in the gas-liquid separation pipe 2. The floating ball 10 is as Figure 3 shown. It has thorns 11 on its surface, which can better separate gas and liquid in the gas-liquid separation pipe 2 and defoam the bubbles formed on the liquid surface to ensure the accuracy of measuring the liquid level height in the subsequent pipeline.

[0015] Working process:

[0016] Install the present utility model in a single-well oil transmission pipeline. The three-phase (oil, water, gas) medium produced by the oil well enters the gas-liquid separation pipe 2 through the liquid inlet pipe 1. Gas-liquid separation is carried out through gravity sedimentation and cross-flow in the gas-liquid separation pipe 2. Then the liquid settles into the liquid pipe section 3, and the gas rises into the gas pipe section 4. Taking the stroke time of the pumping unit as the monitoring and calculation flow period, the three-phase flow is calculated respectively. The process is as follows:

[0017] After the gas enters the gas pipe section 4, it flows through the vortex flowmeter 5, and the current gas flow is detected in real time. The PLC accumulates and measures it;

[0018] After the liquid settles into the liquid pipe section 3, the following operations are carried out:

[0019] 2.1 The oil-water analyzer 6 monitors the water content change of the liquid in real time (outputs a 4-20 mA signal),

[0020] which is collected by the PLC and the oil water content value in this monitoring period is calculated;

[0021] 2.2 The radar level gauge 7 monitors the change in the liquid level height in the pipeline in real time. The PLC calculates the cross-sectional area occupied by the liquid in the pipeline based on the liquid level height. Since the liquid forms a slug flow in the pipeline, the liquid level measured by the radar level gauge 7 is a continuously changing quantity. The liquid level height in the pipeline measured is as Figure 4 shown. Therefore, the PLC can perform a collection every 50 milliseconds and calculate the corresponding cross-sectional area;

[0022] 2.3 The liquid drives the impeller of the impeller tachometer 8 to rotate. The PLC will collect the number of pulses generated by the impeller in real time. The PLC can calculate the liquid flow rate based on the number of pulses;

[0023] 2.4 The PLC can calculate the current liquid flow rate based on the liquid cross-sectional area and the flow rate at the collection moment, and accumulate the current liquid flow rate value within the current monitoring period to obtain the total liquid flow rate. By multiplying the total liquid flow rate within the period by the water content rate within this period, the water production within this period can be obtained. The difference between the total liquid flow rate and the water production is the crude oil volume within this period.

[0024] Finally, the PLC accumulates the measurement values of the three-phase flow within the current monitoring period respectively, completes the statistics of the actual production of oil, water and gas for a single well throughout the day, and realizes the full automation of the three-phase metering of the oil well.

Claims

1. A three-phase flow online metering system applied to a single well oil pipeline, characterized by: An oil inlet pipe (1) is provided, the outlet of the oil inlet pipe (1) is connected to a gas-liquid separation pipe (2), the lower end of the gas-liquid separation pipe (2) is connected to a horizontally placed liquid pipe section (3), the upper end of the gas-liquid separation pipe (2) is connected to an inlet of a gas pipe section (4), the outlet of the gas pipe section (4) is connected to the liquid pipe section (3), a vortex flowmeter (5) is installed on the gas pipe section (4), an oil-water analyzer (6), a radar level gauge (7) and an impeller velocimeter (8) are installed on the liquid pipe section (3) located between the gas-liquid separation pipe (2) and the outlet of the gas pipe section (4), and the vortex flowmeter (5), the oil-water analyzer (6), the radar level gauge (7) and the impeller velocimeter (8) are connected to a controller (9).

2. The three-phase flow online metering system applied to a single well oil pipeline according to claim 1 is characterized in that: The gas-liquid separation tube (2) has a built-in float (10), and the surface of the float (10) has thorns (11).

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