RU38944U1 - DEVICE FOR DETERMINING THE VOLUME SHARE OF WATER IN A PIPELINE WITH A GAS-LIQUID MIXTURE - Google Patents

Abstract

The utility model relates to the field of measurement technology and can be used in the gas and oil industry to determine the volume fraction of water in a pipeline with a gas-liquid mixture without fractioning the products directly at the wells or in the collector sections of the primary processing of gas condensate and oil and gas fields in real time. EFFECT: increased accuracy of determining the volume fraction of water in a gas-liquid mixture flow in a pipeline by eliminating the influence of its salinity on the measurement results. In a device containing a piece of pipe made of dielectric material, passed through turns of two identical coils connected to a reference coil and the other to measuring oscillators, an electric screen with a longitudinal slot (Faraday screen) is placed inside the coil connected to a reference oscillator, covering the pipe.

Description

The utility model relates to the field of measurement technology and can be used in the gas and oil industry to determine the volume fraction of water in a pipeline with a gas-liquid mixture (GHS) without dividing into fractions of the products of production directly at the wells or in the collector sections of the primary processing of gas condensate and oil and gas fields in real time scale.

In the flow metering of GHS, separators are widely used, which provide periodic monitoring of the component flow rate of GHS. Recently, real-time flow metering of multiphase flows has been intensively developing, mainly for oil production. Meters have been created on the integrated use of classic single-phase flow meters, for example, turbine, diaphragm, Coriolis, Venturi nozzles and others. However, such measuring tools are not widely used, mainly due to low reliability, when operating in multiphase flows of oil and gas wells.

A device for determining the volumetric water content in the flow of GHS described in the work: Daisake Yamazaki, Shuichi Haruyama. Development of multiphase flowmeter without radioactive sourse. - Yokogava, Electric Corporation: Collected - BP Exploration Multiphase Mesurement Course, 1997, p. 69.

This device includes a built-in measuring section narrowed in cross section, speed, pressure and temperature meters, a control and computing unit. The measuring section is covered by two ring electrodes (sensitive elements) mounted parallel to each other and concentrically to the pipe. One electrode connected

with an AC voltage source, the other with the input of a capacitive current meter. The current value is determined by the capacitance between the electrodes, which depends on the dielectric constant of the stream, which, in turn, depends on the volumetric water content in the stream. The disadvantages of this device include the small length of the area of interaction of sensitive elements with the flow, which makes spatial integration of variables of density and flow velocity difficult, therefore, the measurement accuracy is reduced. In addition, the salinity of the water, which affects its conductivity, and, as a result, the measurement accuracy, is not taken into account.

Devices are known where a multi-turn coil is used as a sensitive element, for example, in conductivity probes (N. Hind, H. Horton. Microwave plasma diagnostics. - Atomizdat, 1968, p. 351). But conductivity probes that take into account the influence of salinity cannot be used to measure the proportion of water in the GHS stream.

Closest to the claimed is a device for determining the volume fractions of oil, gas and water in a liquid stream in a pipeline (US patent G 01 N 22/04 US 5389883 "Mesurement of gas and water content in oil" (prototype)).

The device contains a piece of dielectric pipe, passed through the turns of many coil resonators with different resonant frequencies. Coil resonators are combined into many groups, each of which includes many resonators having the same natural frequency. The resonant frequencies of the resonators depend on the dielectric constant and volumetric content of the materials flowing through the pipe. By measuring changes in resonant frequencies, the proportions of oil, gas, and water in the stream can be calculated.

The main disadvantage of this device is the low accuracy of measuring the volume fraction of water in the stream due to the impossibility of taking into account its salinity.

In addition, the measuring section of the device has a cumbersome design, requires complex and time-consuming settings and adjustments, including turning, moving and fixing the resonators along the pipe, calibrating the device at all positions of the resonators, etc.

The technical result of the claimed utility model is to increase the accuracy of determining the volume fraction of water in the GHS stream in the pipeline by eliminating the influence of its salinity on the measurement results.

The technical result is achieved by the fact that in a device containing a piece of pipe made of dielectric material, passed through the turns of two identical coils, one connected to a reference one, the other to a measuring self-oscillator, an electric screen with a longitudinal slot is placed inside the coil connected to a reference self-generated generator (screen Faraday) covering the pipe.

Figure 1 shows a device built into the pipeline.

The device for determining the volume fraction of water in a pipeline with a gas-liquid mixture, shown in figure 1, contains a piece of pipe 1 made of a dielectric material, placed in a durable housing 2 between the input 3 and output 4 diffusers. The inner cross section of the pipe 1 in order to create a homogenized (uniform cross-section) GHS flow over the area is much smaller than the cross-section of the pipeline 5. A coil 6 is wound on the pipe 1, connected to a reference oscillator 7, and a coil 8, connected to a measuring oscillator 9. In this case, coil 6 wound directly on the electric screen 10 with a longitudinal slit 11 (Faraday shield), covering the pipe 1 and preventing the interaction of the electric field of the coil with the flow of GHS. Autogenerators 7 and 9 for receiving short connections with coils are placed in a removable block 12 mounted on the housing 2.

The device is built into the pipeline in the immediate vicinity of the well. Before operation, the device is configured, adjusted and calibrated.

Using self-oscillators, a magnetic field inside the coil 6 and an electromagnetic field inside the coil 8 are excited, the self-oscillators are tuned to the same frequency and its value F _o is measured in the absence of the GHS flow in the pipe 1.

During calibration, the frequencies of the reference F _op and the measuring F _{ISM of the} oscillators are measured during the flow of the GHS with a known volumetric water content. The change in the frequency of the reference oscillator ΔF _op equal to

ΔF _op = F _op -F _o = ΔF _magn

where F _o - the frequency of the reference oscillator in the absence of flow;

F _op - the frequency of the reference oscillator during flow;

ΔF _magn - change in the frequency of the reference oscillator due to a change in the magnetic field during flow, due to the influence of the conductivity (salinity) of water on the magnetic field of coil 6, and a change in the frequency of the measuring oscillator ΔF _ISM equal to

.DELTA.F _{ism ism} -F = F = ΔF _{of the mag} + ΔF _electric,

where F _o is the frequency of the measuring oscillator in the absence of flow;

F _ISM - frequency measuring oscillator during flow;

ΔF _magn - change in the frequency of the measuring oscillator due to changes in the magnetic field during the flow,

ΔF _electron is a change in the frequency of the measuring oscillator due to a change in the electric field during the flow, due to the influence of both the conductivity of the water on the magnetic field of coil 8 and the dielectric constant of the GHS flow on the electric field of this coil. When the coils are identical in the difference in frequency changes

_Edited -ΔF _op ΔF = ΔF + ΔF _{magn RE} -ΔF _magn = Δ _Felektr

changes caused by the influence of conductivity cancel each other out, therefore the frequency difference

(F _meas -F _o ) - (F _op -F _o ) = F _meas -F _op = ΔF _electron

is determined by the influence of only the dielectric constant of the GHS stream, proportional to the volume fraction of water in the stream Θ _in , on the electric field of coil 8. The proportionality coefficient k (changing the frequency difference by one percent of the volume fraction of water in the stream) is set when the device is calibrated while the GHS stream passes through it with a known volumetric water content according to the formula:

k = (F _meas -F _op ) / Θ _c .

During operation, the volume fraction of water © in the GHS stream is calculated by the formula:

Θ _in = (F _meas -F _op ) / k,

where F _ISM is the frequency of the measuring oscillator during the flow of the GHS;

F _op - the frequency of the reference oscillator during the flow of the GHS;

k is the coefficient of proportionality established during calibration of the device. The value of the coefficient k does not depend on the salinity of the water in the stream.

Improving the accuracy of determining the volume fraction of water in the pipeline with GHS contributes to lower costs in the collector sections of the primary processing of gas condensate or oil and gas fields, as well as more accurate prediction of well life.

Claims (1)

A device for determining the volume fraction of water in a pipeline with a gas-liquid mixture, containing a pipe segment of dielectric material, passed through the turns of two identical coils connected: one with a support coil and the other with a measuring oscillator, characterized in that inside the coil connected to a reference oscillator , placed an electric screen with a longitudinal slit (Faraday screen), covering the pipe.