RU2439316C2 - Measurement method of oil and associated gas flow rates in oil wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: measurement method of oil and associated gas flow rates in oil wells involves supply of extracted products from tubing string to separator. Products are separated in the separator into gas and oil. Oil and gas are extracted subsequently from separator and they are measured by means of a float and flow switch as to the time of filling and emptying of the separator measuring part respectively. At that, during measurement periods there performed is extraction of gas separated at the bottom-hole pump inlet from annular space of the well and it is supplied directly to gas cavity of separator.

EFFECT: improving measurement accuracy of oil and associated gas flow rates.

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Description

The invention relates to the oil industry and can be used to measure the production of oil wells.

To measure the gas-liquid flow of an oil well, a method is known according to which the flow direction of the measured flow is periodically changed into a metering chamber made of two vertically mounted tight cylinders interconnected in the upper part by a pipeline, the filling time and the emptying time of the cylinders are determined, by which the liquid flow rates are determined and gas / 1 /. The disadvantage of this method is the low accuracy of the measurement of flow rates due to mixing of the gas-liquid mixture when it enters the sealed cylinders and the deterioration of the separation of free gas from oil in the same period.

Closest to the proposed invention is a method of periodic selection of oil and water from a separation tank using the device described in / 2 /.

The oil-gas mixture entering the separator is stratified into gas, oil and water. At the oil-water interface is a spherical float of intermediate density. With the accumulation of the aqueous phase in the separator, the oil-water separation level rises and the oil flows through the upper discharge line to the pressure network. When the upper preset position is reached, the float closes the oil access to the bypass line and the pressure immediately increased in the separator will switch the two-sided piston of the flow switch to another position at which the discharge from the water phase separator through the lower bypass line will begin. The accumulation of oil in the separator will lead to a decrease in the oil-water level, and when the float reaches its lowest position, the two-sided piston switches to pumping oil, etc.

The disadvantage of this method is the difficulty of achieving a clear level of phase separation with simultaneous processes of the mixture entering the separator and dividing it into phases, which leads to disruptions in the operation of the flow switch.

The aim of the invention is to increase the accuracy of the measurement of oil and gas production wells.

This goal is achieved by the fact that in the known method of measuring oil and gas production, including the flow of produced products from the tubing string into the separator, the separation of products in the separator into gas and oil, sequential selection from the oil and gas separator and their measurement in time, respectively filling and emptying the measuring part of the separator, carried out using a float and a flow switch, during the measurement period, the gas separated from the annulus ostrantsva well and send it directly to the gas space of the separator.

Figure 1 and 2 presents a diagram of the implementation of the method. A pump (not shown) was launched into the well 1, the pressure part of which is in communication with the tubing string 2.

At the exit from the well, the tubing string 2 has a valve 3, which is connected to a line 4 connecting it to the separator 5. The annular space of the well 1 through the valve 6 and line 7 is communicated with the upper part of the separator 5. Inside the separator, a vertical the perforated pipe 8 with the float 9 inside and the seat saddles 10 and 11. The upper part of the pipe 8 is connected to the right side of the flow switch 13 using the upper branch line 12, and the lower part of the pipe 8 is connected to the left side using the lower branch line 14 the flow switch 13. The flow switch 13 is made in the form of a cylinder, inside of which there is a double-sided piston with the left 15 and right 16 parts with through holes in them and a blank partition 17. Permanent magnets 18 and 19 are ring-shaped in the end parts of the switch 13. The flow switch 13 using a line 20 is connected through a valve 21 with a flow collector 22 of the well. In front of the valve 3, a valve 23 is installed on the pipe string 2, which communicates the tubing with the collector 22 through the pipe 24. A burst valve 25 is located between the valves 21 and 23.

The method is as follows.

In the absence of measurement of production oil and gas production rates, the product is directly pumped to the collector 22 through tubing (2), open valves 23, 25 and line 24. At the same time, valves 3, 6, 21 remain closed.

In the mode of measuring the flow rates of liquid and gas, the product from the tubing 2 through the open valve 3 and line 4 enters the separator 5. The valves 6 and 21 open and the burst valve 25 closes. In the separator 5 from the reservoir oil, the residual amount of free gas is separated. In this case, the main part of the free gas phase, separated at the pump intake, is simultaneously fed into the gas part of the separator through the open valve 6 and line 7. The accumulation of oil in the separator leads to an increase in the oil-gas level in the separator. This level is followed by a float 9. During this period, the gas phase passes through line 12, the hole in the right-hand side 16 of the two-sided piston of switch 13 enters line 20 and then into manifold 22. During this period, the time for filling the measuring part of the separator 5 with liquid is measured, which further transferred to the flow rate of the well by fluid.

After the float 9 reaches the upper extreme position and blocks the landing seat 10, the gas access to the line 12 will stop and the pressure in the separator 5 will increase stepwise. This pressure will cause the two-sided piston to move to the extreme right position, allowing fluid to enter line 20 through the lower outlet 14 and the left part of the piston 15. At the same time, the separator emptying cycle begins and the well gas flow rate at the collector pressure is calculated from the emptying time of the separator measuring part. The float 9, having reached its lowest position, will block the seat 11 and stop the fluid from accessing line 20. The resulting pressure in the separator through line 12 will cause the double-sided piston to move to its extreme left position, etc.

The supply of the switch with permanent magnets allows the two-sided piston to be fixed in only two extreme positions.

The receipt of a significant (more than 50%) amount of already-associated associated gas from the annulus into the gas part of the separator 5 allows to reduce the gas separator load, i.e. facilitate and improve the separation of well production into liquid and gas, obtain a clearer interface, ensure the accuracy of the flow switch and increase the accuracy of flow rates measurement.

The technical and economic advantage of the method is the possibility of reducing the volume of the separator in connection with a decrease in gas load.

Literature

1. RF patent No. 1777446, cl. G01F 3/18, 1993

2. USSR author's certificate No. 1725955, cl. B01D, 19/00, 1987

Claims (1)

A method for measuring oil and associated gas production rates of oil wells, including the input of produced products from the tubing string into the separator, separation of the products in the separator into gas and oil, sequential selection from the oil and gas separator and their measurement by time, respectively, of filling and emptying the measuring part separator, carried out using a float and flow switch, characterized in that, in order to improve the accuracy of measuring the flow rate of oil and associated gas, during the measurement period p at reception of separated downhole pump gas from the annular space of the well and send it directly to the gas space of the separator.

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