CN208140194U - Positive displacement oil gas water three phase flow separate phase flow rate on-line measurement device - Google Patents

Abstract

The utility model provides a volumetric oil-gas-water three-phase flow on-line measuring device for phase separation flow, which belongs to the technical field of multiphase flow measurement. The device is mainly composed of two standard containers with liquid level sensors, two single-phase gas flowmeters, six control valves and multiple pipelines; due to the use of fixed-volume standard containers, it can accurately measure the The volume flow of liquid phase fluid, combined with gas measurement, density measurement and water cut measurement, can further calculate the phase separation flow of oil-gas-water three-phase flow, including cumulative volume flow and cumulative mass flow. In the device, the two standard containers alternately collect and discharge liquid, which can realize the stable measurement of the liquid phase fluid flow in the pipeline, ensure the speed of measurement, and lay a foundation for better realization of on-line measurement. The device utilizes the volumetric principle, reduces the complexity of mixed-phase measurement during measurement, and greatly reduces measurement cost while improving measurement accuracy.

Description

Volumetric Oil-Gas-Water Three-Phase Flow On-Line Measuring Device

technical field

The utility model relates to an on-line measuring device for oil-gas-water three-phase flow split-phase flow, which belongs to the technical field of multiphase flow measurement.

Background technique

In the industrial field, measurement technology plays a very important role, such as petrochemical industry, environmental protection and so on. Multiphase flow exists widely in many scientific and engineering fields, and its application is ahead of theoretical research. The study of multiphase flow detection technology is due to the needs of practical applications, and secondly, it can provide an important auxiliary means for the theoretical research of multiphase flow. Compared with single-phase flow, multiphase flow has more complicated flow characteristics due to the existence of interface effects and relative velocities between different phases, and the phase interface changes randomly in time and space. For a long time, two-phase flow parameter detection, as an important auxiliary means of two-phase flow theory research, has been a challenging problem worldwide. It is called the ultimate challenge of process measurement and has become an important problem in modern technology and developed industrial countries. scientific research field. Multiphase flow detection and monitoring has very important theoretical significance and application value for related scientific research (such as two-phase heat and mass transfer research) and safe and efficient operation of process equipment.

In order to realize the accurate measurement of the flow rate of the multiphase flow, the traditional method is to use a separation device to separate the components of the multiphase flow, and then use a mature single-phase flow meter to measure the flow rate of the separated single-phase fluid. Measurement. Although the accuracy of this method is high, the separation device usually requires a very high economic investment, and the separation process usually takes several hours for reliable measurement, and it is difficult to achieve real-time online measurement. Therefore, accurate online measurement of multiphase fluids is still a worldwide problem.

Taking the wellhead oil-gas-water three-phase flow in oil exploitation as an example, the main components of crude oil produced from the wellhead in oil exploitation production are oil-gas-water, and may also contain sediment, which belongs to the category of multiphase flow. For oil-gas-water three-phase flow in oil production, the main parameters to be measured include temperature, pressure, phase fraction (gas fraction, water fraction, oil fraction), fractional flow rate and other process parameters, as well as density, Salinity and other physical parameters. The relevant technologies related to temperature and pressure measurement are relatively mature, and it is only necessary to directly adopt the mainstream technology of existing industrial applications. However, due to the complexity of multiphase flow itself, its practical application in engineering is far ahead of theoretical research, involving the calculation of multiphase flow separation phase holdup (gas content, water content, oil content), phase separation flow rate and salinity and other parameters. Measurement, especially online measurement technology is still a worldwide problem. Taking flow measurement as an example, most industrial flowmeters for single-phase fluids can easily achieve an accuracy of 1% or 0.5%, but for industrial multi-phase flows, most of the existing measurement methods or commercial measurement instruments have low accuracy or measurement methods Complicated, such as the RedEye multiphase flow measurement system invented by Weatherford International Co., Ltd., which uses the difference in density to realize the separation of gas and liquid, but the system involves many sensors and the measurement method is relatively complicated. It is generally accepted in the industry that if an online measurement accuracy of 10% can be achieved, it can be popularized and applied in industrial practice. Although the separation of multiphase fluid into single-phase fluid by separator can obtain high accuracy, but due to poor real-time performance and high investment cost, it is difficult to measure oil-gas-water three-phase flow at the wellhead of a single well Promoted, greatly reducing its value in industrial production.

Therefore, it has long been a difficult problem and an important demand in oil production to realize the on-line measurement of the flow rate of oil-gas-water three-phase flow without phase separation.

Utility model content

The purpose of this utility model is to overcome the deficiencies of the prior art, and propose a volumetric oil-gas-water three-phase flow on-line measuring device for phase flow, which can realize the oil-gas-water three-phase flow in the mixed phase On-line measurement of split-phase flow under certain conditions.

In order to achieve the above object, the utility model adopts the following technical solutions:

A volumetric oil-gas-water three-phase flow split-phase flow online measurement device, mainly composed of two standard containers with liquid level sensors, two single-phase gas flowmeters, six control valves and multiple pipelines, The first control valve (V1-1), the third control valve (V1-2) and the sixth control valve (V2-3) together constitute the first valve group, the second control valve (V2-1), the fourth control valve (V2-2) and the fifth control valve (V1-3) jointly constitute the second valve group; wherein, the oil-gas-water three-phase inlet respectively passes through the first pipeline with the first control valve, and the second The second pipeline of the control valve communicates with the three-phase inlet on the top of the first standard container and the three-phase inlet on the top of the second standard container; The gas flow meter is communicated with the third pipeline of the third control valve; the gas phase inlet at the top of the first standard container communicates with the gas phase outlet at the top of the second standard container by being provided with the fourth pipeline of the second gas flow meter and the fourth control valve; The drain outlets at the bottom of the first standard container and the bottom of the second standard container are respectively communicated with the liquid phase outlet through the fifth pipeline provided with the fifth control valve and the sixth pipeline provided with the sixth control valve; the volume of the two standard containers V is equal and fixed;

The signal of the liquid level sensor of the standard container is used to trigger the opening and closing of two control valve groups; and when the first valve group is opened and the second valve group is closed, the first standard container is in a liquid collection state, and the second standard container It is in the liquid discharge state; when the first valve group is closed and the second valve group is opened, the first standard container is in the liquid discharge state, and the second standard container is in the liquid collection state.

Features and beneficial effects of the utility model are:

The structure of the device is simple and the cost is low. When using this device to measure multiphase fluid, since a standard container with a fixed volume is used, the volume flow rate of the liquid phase fluid in the multiphase flow can be accurately measured. Combined with gas measurement, density Measurement and water cut measurement can further calculate the phase separation flow of oil-gas-water three-phase flow, including cumulative volume flow and cumulative mass flow. In the device, the two standard containers alternately collect and discharge liquid, which can realize the stable measurement of the liquid phase fluid flow in the pipeline, ensure the speed of measurement, and lay a foundation for better realization of on-line measurement. Moreover, the device is inspired by the principle of volumetric flow measurement, reduces the complexity of mixed-phase measurement during measurement, and greatly reduces the cost of measurement while improving measurement accuracy.

Description of drawings

Fig. 1 is a schematic diagram of the volumetric multiphase flow on-line measurement device proposed by the utility model.

In Figure 1, V1-1, V1-2, and V1-3 are the three control valves of the pipeline where standard container 1 is located, and V2-1, V2-2, and V2-3 are the three control valves of the pipeline where standard container 2 is located. control valve.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the technical scheme of the utility model is further described as follows:

The device proposed by the utility model is mainly used to realize the on-line measurement of the phase-separated flow of the oil-gas-water three-phase flow. As shown in Figure 1, the device is mainly composed of two standard containers with liquid level sensors, two single-phase gas flowmeters, six control valves and multiple pipelines. The first control valve V1-1, the third control valve The valve V1-2 and the sixth control valve V2-3 together form the first valve group, and the second control valve V2-1, the fourth control valve V2-2 and the fifth control valve V1-3 together form the second valve group; , the oil-gas-water three-phase inlet passes through the first pipe a with the first control valve V1-1, the second pipe b with the second control valve V2-1 and the three-phase inlet at the top of the standard container 1 A. The three-phase inlet E at the top of the standard container 2 is connected; the gas phase outlet B at the top of the standard container 1 and the gas phase inlet F at the top of the standard container 2 pass through the third valve with a single-phase gas flowmeter 1 and a third control valve V1-2 The pipeline c communicates; the gas phase inlet C on the top of the standard container 1 communicates with the gas phase outlet G on the top of the standard container 2 through the fourth pipeline d provided with a single-phase gas flowmeter 2 and the fourth control valve V2-2; the bottom of the standard container 1 The liquid outlet D and the liquid outlet H at the bottom of the standard container 2 communicate with the liquid phase outlet through the fifth pipe e provided with the fifth control valve V1-3 and the sixth pipe f provided with the sixth control valve V2-3 respectively ; The volume V of two standard containers is equal and fixed.

Trigger the opening and closing of the two valve groups according to the signal of the liquid level sensor in the standard container; and when the first valve group is opened and the second valve group is closed, the standard container 1 is in the liquid collection state, and the standard container 2 is in the liquid discharge state; when When the first valve group is closed and the second valve group is opened, the standard container 1 is in the liquid discharge state, and the standard container 2 is in the liquid collection state.

All components in the on-line measurement device of the embodiment of the utility model are conventional products. The specification (volume) of the standard container is determined according to the flow rate of the multiphase fluid to be measured, that is, the larger the flow rate of the multiphase fluid to be measured, the larger the specification of the standard container, and vice versa, the smaller the specification of the standard container. Assuming that the volume flow rate of the liquid phase fluid is 1m ³ /h, a standard container with a diameter of 100mm and a height of 500mm can be designed, and its inlet and outlet pipe diameters can be designed to be 50mm (industrial field wellheads are generally 50mm).

The workflow of the online measuring device is:

1) Data collection:

1.1) Make the first valve group (V1-1, V1-2 and V2-3) in the open state, and the second valve group (V2-1, V2-2 and V1-3) in the closed state; record the standard container 2 Liquid discharge times n ₂ =n ₂ +1, n ₂ is a non-negative integer (the initial value of n ₂ is 0);

1.2) The oil-gas-water three-phase flow flows into the standard container 1 from the top through the pipeline a, and the gas-liquid separation is automatically completed in the standard container 1 by using the gravity of the fluid itself, and the separated gas phase passes through the pipeline c connected to the top of the standard container 1 Enter the standard container 2 and push the previously collected liquid in the standard container 2 to discharge (for the initial situation, then empty). The conventional single-phase gas flowmeter 1 installed on the connecting pipeline c measures the separated gas flow;

1.3) Use the liquid level sensor installed on the standard container 1 to detect whether the standard container 1 is full of liquid, when the liquid level sensor detects that the standard container 1 is full of liquid, perform step 1.4); otherwise, return to step 1.2);

1.4) Close the first valve group (V1-1, V1-2, and V2-3), open the second valve group (V2-1, V2-2, and V1-3), and record the number of discharges n _{1 of the standard container 1} =n ₁ +1, n ₁ is a non-negative integer (the initial value of n ₁ is 0);

1.5) The oil-gas-water three-phase flow flows into the standard container 2 from the top through the pipeline b, and the gas-liquid separation is automatically completed in the standard container 2 by the gravity of the fluid itself, and the separated gas phase enters through the pipeline d connected to the top of the standard container 2 The standard container 1 pushes the previously collected liquid in the standard container 1 to drain (for the initial situation, it is empty). During this process, the standard container 2 collects liquid, and the standard container 1 discharges liquid; The conventional single-phase gas flow meter 2 installed on the road d measures the separated gas flow;

1.6) Use the liquid level sensor installed on the standard container 2 to detect whether the standard container 2 is full of liquid. When the liquid level sensor detects that the standard container 2 is full of liquid, perform step 1.7), otherwise return to step 1.5);

1.7) Determine whether the current measurement time period t is greater than or equal to the set measurement time period t ₀ , if so, execute step 1.8), otherwise return to step 1.1), make standard container 1 and standard container 2 enter reciprocating alternate collection and emptying Liquid phase workflow;

1.8) Statistically count the draining times n ₁ and n ₂ of the standard container 1 and the standard container 2 respectively; measure the oil phase density ρ _o , the water phase density ρ _w and the gas phase density ρ _g respectively with a density measuring instrument; perform step 2);

2) Data processing:

2.1) Since the volume of the standard container is fixed, according to the signal of the liquid level sensor in each standard container, count the number of discharges of liquid from standard container 1 and standard container 2 within the measurement period t (that is, n ₁ and n ₂ in step 1.8 ), then the cumulative volume flow rate of the liquid phase flowing through the pipeline in the time period t is calculated by formula (1):

Q _v ＝(n ₁ +n ₂ )V (1)

In the formula, Q _v is the cumulative volume flow rate of the liquid phase (oil phase and water phase) in the pipeline of the online measuring device within the measurement period t, V is the volume of the standard container, and t is the measurement period (t The value of can be taken according to the commonly used unit time, and can also be set according to the needs of use), _n1 and _n2 are respectively the times of liquid discharge of standard containers 1 and 2 within the measurement period t;

2.2) Using the obtained cumulative volume flow Q _v of the liquid phase, combined with the water content, the cumulative volume flow of the oil phase and the water phase in the liquid phase within the measurement period t can be obtained as follows:

In the formula, Q _v is the cumulative volume flow rate of the liquid phase in the measurement period t calculated in step 2.1), Q _o is the cumulative volume flow rate of the oil phase in the measurement period t, and _Qw is the cumulative volume flow rate of the water phase in the measurement period t, α is the water cut (the water cut is the ratio of the cumulative volume flow of the water phase to the cumulative volume flow of the liquid phase, which can be obtained by conventional measurement methods);

2.3) Using the obtained Q _o and Q _w , combined with the measured oil phase density ρ _o and water phase density ρ _w , the cumulative mass flow rates of the oil phase and water phase in the liquid phase within the measurement period t are respectively obtained as:

In the formula, M _o is the cumulative mass flow rate of the oil phase in the time period t, and _Mw is the cumulative mass flow rate of the water phase in the time period t.

The gas-phase cumulative volume flow Q _g of the multiphase flow obtained by the gas flowmeter installed on the gas-phase pipeline connecting the standard container 1 and the standard container 2, combined with the measured gas-phase density ρ _g , obtains the gas-phase cumulative volume in the measurement period t The mass flow is:

M _g ＝ ρ _g Q _g (4)

In the formula, M _g is the cumulative mass flow rate of the gas phase in the time period t.

So far, the online measurement of the phase-separated flow of the oil-gas-water three-phase flow has been completed, that is, the cumulative volume flow Q _o and cumulative mass flow M _o of the oil phase, the cumulative volume flow Q _w and the cumulative mass flow rate of the water phase within the time period t The mass flow M _w and the cumulative volume flow Q _g and the cumulative mass flow M _g of the gas phase.

The on-line measurement device for multiphase flow split phase flow proposed by the utility model uses a standard container with a fixed volume, so it can accurately measure the volume flow rate of the liquid phase fluid in the multiphase flow, combined with gas measurement, density measurement and water content measurement, The phase separation flow of oil-gas-water three-phase flow can be further calculated, including cumulative volume flow and cumulative mass flow. In the utility model, two standard containers alternately collect liquid and discharge liquid, which can realize the stable measurement of the flow of the liquid phase fluid in the pipeline, ensure the speed of measurement, and lay a foundation for better realization of on-line measurement. Moreover, the utility model is inspired by the volumetric principle, which reduces the complexity of mixed-phase measurement during measurement, and greatly reduces measurement cost while improving measurement accuracy.

Claims (1)

1. A volumetric oil-gas-water three-phase flow phase flow on-line measuring device is characterized in that the device mainly consists of two standard containers with liquid level sensors, two single-phase gas flowmeters, six Control valves and multiple pipelines, the first control valve (V1-1), the third control valve (V1-2) and the sixth control valve (V2-3) together constitute the first valve group, the second control valve (V2 -1), the fourth control valve (V2-2) and the fifth control valve (V1-3) jointly constitute the second valve group; wherein, the oil-gas-water three-phase inflow ports respectively pass through the valves provided with the first control valve The first pipeline and the second pipeline provided with the second control valve communicate with the three-phase inlet on the top of the first standard container and the three-phase inlet on the top of the second standard container; the gas phase outlet on the top of the first standard container is connected to the top of the second standard container The gas phase inlet of the first standard container is communicated with the third pipeline provided with the first gas flow meter and the third control valve; The fourth pipe of the control valve is in communication; the liquid outlets at the bottom of the first standard container and the bottom of the second standard container respectively pass through the fifth pipe provided with the fifth control valve, the sixth pipe provided with the sixth control valve and the liquid phase outlet Connected; the volume V of two standard containers is equal and fixed; The signal of the liquid level sensor of the standard container is used to trigger the opening and closing of the two control valve groups.