RU2383868C2 - Method and device for measurement of gas-liquid mixture and its components flow rate - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention is related to the field of gas-liquid flow rate measurement. Capacity of calibrated chamber is measured under conditions of plant operation in working mode of well. Flow rate of gas-liquid mixture is measured. Besides capacity of calibrated chamber and flow rate of gas-liquid mixture are measured simultaneously in each cycle of calibrated chamber emptying or in specified number of cycles with the help of capacity carrier, for instance tube-piston unit. Device for measurement of gas-liquid mixture flow rate comprises horizontal separator, measuring calibrating chamber arranged in the form of vertical accumulating reservoir, and also pipeline that drains gas-liquid mixture. Separator and calibrating chamber are joined according to principle of communicating vessels by pipelines of gas-liquid and gas line. Pipeline that drains gas-liquid mixture is equipped with carrier of capacity, for instance tube-piston unit.

EFFECT: improved accuracy of flow rate measurement.

2 cl, 1 dwg

Description

The invention relates to the field of oil production and can be used when measuring the average daily mass flow rate of the liquid, the average daily volumetric flow rate of gas and to determine the average daily mass flow rate of oil produced from oil wells, and in other cases when it is necessary to measure the amount of liquid and gas in a multiphase flow at working conditions.

A known method of measuring the flow of liquid and gas, based on the periodic filling with liquid (oil-water mixture) and subsequent emptying (filling with gas) of the measuring (calibrated) chamber, made in the form of a vertical cylindrical tank, equipped with two level sensors (hydrostatic pressure transducers). The liquid flow rate is determined by the rate of filling of the calibrated chamber with liquid, and the gas flow rate is determined by the rate of its emptying.

Also known is a method of measuring the flow of gas-liquid flow, based on alternately filling and emptying the halves of the measuring chamber, made in the form of two vertically mounted cylinders interconnected in the upper part of the pipeline and equipped with upper and lower level sensors, which are used as hydrostatic pressure transducers of the liquid column . Moreover, in this case, the flow rate of the gas-liquid mixture is determined by the speed of emptying the calibrated part of one cylinder, and the fluid flow rate by the speed of the simultaneously flowing filling of the calibrated part of the second cylinder. The known method allows to detect a change in the capacity of one of the cylinders by the difference in their flow readings. However, with the pulsating nature of the gas-liquid mixture intake, it is impossible to use the mentioned sign in practical application.

The disadvantages of the known methods are:

- large measurement error due to the fact that the calibration of the capacity of the measuring chamber is carried out on a bench on the water. However, during operation, the capacity of the calibrated part of the measuring chamber changes due to deposits of sludge and paraffin-resinous compounds on the walls, partitions, dampers, inspection hatches and other elements that are an integral part of real pressure measuring vessels. In addition, when calibrating on water, the calibrated part of the measuring chamber is located between the control lower and upper fittings, the distance of which from the sensitive elements of the level sensors is determined by the design. However, the density of the measured oil-water mixture is always lower than the density of water, and the calibrated part of the measuring chamber, recorded as the difference in the weight of the liquid column between the upper and lower control fittings, moves upward, the higher, the lower the relative density of the measured oil-water mixture;

- the capacity of the calibrated section of the measuring chamber is determined in the factory, not in operating mode and without taking into account the topography of the area where the actual measurement is made. In real conditions, the devices are placed on prepared sites that repeat the terrain, in connection with which the capacity of the measuring chambers changes, which results in a large measurement error;

- opening and closing of the liquid and gas lines is carried out by one device - a three-way valve with an electric drive mounted at the junction of pipelines that discharge gas and liquid from the separator. Thus, with a closed liquid line, the gas line is always open, or vice versa. The presence of such a connection in the design leads to a rarefaction of the separator during filling of the measuring chamber, while the condition of equilibrium of the system is violated, which negatively affects the metrological characteristics of the installation;

- the sensitive elements of the liquid level sensors are located in the zone of the active separation stage due to the influence of the medium caused by the pulsating mode of supply of the gas-liquid mixture, foaming, unsteady hydrostatic level, the measurement error increases.

The aim of the invention is to improve the accuracy of measuring the flow rate of a gas-liquid mixture and its constituent components.

According to the claimed method, improving the accuracy of measuring the flow rate of a gas-liquid mixture and its constituent components is achieved by calibrating (determining the capacity) of the measuring chamber in the operating mode of the wells using, for example, a piston-piston unit (unidirectional or bi-directional action) with a certain capacity. At the same time, the device uses an auxiliary vertical storage tank articulated with a horizontal separator according to the principle of communicating vessels as a measuring chamber. The vertical tank is equipped with one or two liquid level sensors.

Comparison of the proposed solution not only with the prototype, but also with other technical solutions in this area revealed the signs that distinguish the claimed solution from the prototype, which allows us to conclude that the criterion of "significant difference". Comparative analysis with the prototype shows that the inventive method and device for measuring the flow rate of a gas-liquid mixture and its constituent components is characterized in that it excludes the influence of changes during operation, the capacity of the measuring chamber due to deposits of paraffin-tar substances and sludge, the influence of changes in the density of the oil-water mixture is excluded, included in the gas-liquid stream.

Thus, the inventive method and device for measuring a gas-liquid mixture and its constituent components meets the criterion of "novelty." The drawing shows an equivalent diagram of one of the embodiments of the proposed method and device.

The device includes a horizontal separator (1), a vertical storage tank (2), interconnected by pipelines of a liquid (3) and a gas line (4), an inlet pipe (6) that supplies a gas-liquid mixture to the separator, a pipeline (7) of the upper overflow and a gas outlet line, a pipeline (8) of the lower overflow and gas outlet line, a liquid pipeline (9), a pipeline (10) that discharges a gas-liquid mixture and is equipped with a pipe-piston block (11) with expanders at the ends, including a calibrated pipe with a piston azdelitelem, detectors S ₁ and S ₂ and a flow switch (12). The vertical storage tank is equipped with one or two converters of a hydrostatic liquid column (5). In the initial position, the gas-liquid flow enters the separator and is divided into liquid and gas. The released gas tends to the upper cavity of the separator, the liquid accumulates in the lower part of the separator, passes through the pipeline (3) into the vertical storage tank. During filling of containers with liquid, a controlled valve (13), a differential controller (14) at the outlet pipe (10) in the closed position, accumulate (grow) and level the liquid. Upon reaching a differential value sufficient to overcome the resistance created by the differential pressure regulator (while its valve is ajar), the gas flows through the pipe-piston block expander into the manifold, the liquid level continues to rise to the level of the overflow. The liquid begins to flow through the pipelines of the exhaust lines and the piston block, displacing the gas into the manifold. Gas and liquid, which continue to flow into the separator, create a pressure drop that exceeds the total resistance of the piston separator and the differential controller. The piston begins to move along the calibrated pipe of the pipe-piston block and the liquid level in the separator begins to decrease.

After several idle strokes of the piston separator, necessary to stabilize the drain of liquid from the separator, the controller begins to measure the capacity of the calibrated part of the measuring chamber. In this case, after the first detector (for example, S ₁ ) triggers the first "working" stroke of the piston separator through the calibrated pipe, the controller fixes the output signal of the lower level sensor (U ₁ ) and takes this value as the upper setting of the calibrated part of the measuring chamber, starts counting the time of its emptying and calculating the average value of the flow rate of the gas-liquid mixture by the average speed of the piston separator along a calibrated pipe of known capacity between the detectors S ₁ and S ₂ . After the liquid level reaches a predetermined lower value, after the second detector (for example, S ₂ ) triggers the last "working" stroke of the piston separator through the calibrated pipe, the controller again records the value of the output signal of the level sensor (U ₂ ), takes this value as the lower setting of the calibrated part of the measuring chamber, ends the countdown time for its emptying, determines the resulting average value of the flow rate of the gas-liquid flow measured by the piston block and the capacity of the calibrated h Part of the measuring chamber. At the same time, the pipe-piston unit, while continuing to work, displays the piston separator in one of the pipe-piston block expanders, a controlled valve (13) opens on the pipeline (9). The liquid level drops below the lower set point until a certain free volume is obtained to stabilize the process of subsequent liquid filling. Then the controller stops the piston-piston block, closes the controlled valve (13) on the pipeline (9), the liquid again begins to accumulate in the measuring chamber. As the level of inflow increases, when it reaches the lower set point, the controller starts, and when it reaches the upper set point, it ends the countdown of the filling time, calibrated during the previous cycle of emptying part of the measuring chamber.

The process of measuring the flow rate of the liquid ends and the process of measuring the flow rate of the gas-liquid mixture begins again as described above.

The flow rate of the gas-liquid mixture is calculated by the average speed of the piston separator through a calibrated pipe with a known capacity between the detectors.

The liquid flow rate is calculated by the filling speed of the calibrated (when draining the liquid) part of the measuring chamber.

The gas flow rate is calculated as the difference between the flow rates of the gas-liquid mixture and liquid.

Under the condition of stability of the discharge process, i.e. the presence of gas in the production of wells, after performing a series of measurements to determine the capacity of the calibrated section of the measuring chamber, the installation can be switched to normal operation.

Information sources

1. RF patent No. 2125651 OZNA-MICRON

2. Copyright certificate SU 1553661 A1, publ. 03/30/90

3. Patent No. 1777446, registered in the State Register of Inventions 05/18/93

Claims (2)

1. A method of measuring the flow rate of a gas-liquid mixture and its constituent components, which consists in cyclically filling the measuring calibrated chamber with liquid and emptying it when filling with gas, determining the capacity of the calibrated chamber under the operating conditions of the installation in the operating mode of the well, measuring the flow rate of the gas-liquid mixture and its gas and liquid namely, oil and water, characterized in that the capacity of the calibrated chamber and the flow rate of the gas-liquid mixture are measured simultaneously in each empty cycle Ia calibrated chambers or through a predetermined number of cycles the capacity of the carrier via, for example, of pipe block. 2. A device for measuring the flow rate of a gas-liquid mixture and its constituent components, comprising a horizontal separator and a calibrated measuring chamber made in the form of a vertical storage tank, connected to the separator, equipped with one or two liquid level sensors, and also a pipeline discharge the gas-liquid mixture, characterized in that the separator and the calibrated chamber are connected according to the principle of interconnected vessels by pipelines of a liquid and gas line, and the pipeline discharging gas-liquid cm Here, it is equipped with a capacity carrier, for example, a piston-piston block.