RU2386929C2 - Measuring section of gas-liquid flow metre - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention may find application in operation of gas wells, in plants of complex or preliminary preparation of gas for detection of water-gas and condensate-gas factors (WGF, CGF), which characterise amount of water and hydrocarbon condensate in products produced from gas-condensate wells. One measuring section 1 combines Doppler speed detector and two detectors of flow density, one of which - open cylindrical resonator (OCR) 6 - works on frequencies ~35 GHz (WGF~5-100 cm³/m³), and the other one - closed cylindrical resonator (CR) 16 - operates in frequencies ~1GHz (WGF-50-1000 cm³/m³). Measuring channel is arranged in the form of smooth-walled cylinder with diametre that equals inner diametre of OCR, which results in stabilisation of flow in channel.

EFFECT: expansion of registered WGF and CGF range from 1 to 1000 cm³/m³ and reduced time of measurement.

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Description

The invention relates to the field of measuring equipment and can be used in productive gas condensate wells, in gas treatment plants for transport, gas processing plants for determining gas flow rate, liquid flow rate, water fraction and condensate fraction in a liquid without separating the product into gaseous and liquid phases .

Known devices for determining the flow of gas and liquid in the flows of crude oil [1]. By placing a plurality of resonators on a pipe of dielectric material and measuring the change in their natural frequencies when a gas-liquid stream appears, the volume fractions of oil, water and gas flowing through the pipeline are calculated. Due to the sharp difference in the speeds of oil and gas condensate flows, this method is practically impossible to apply to solve similar problems in the gas industry.

Also known devices using ultrasonic vibrations [2-4]. The speed of sound in a water-oil emulsion depends on the volume concentration of oil and its temperature. By placing pairs of sensors (emitter-receiver) along the pipeline volume and measuring the amplitudes and phases of the ultrasonic (US) signals or their delay at individual points in the measuring section, we can draw conclusions about the speed and density of the medium, and from here calculate the flow rates of gas, oil and water.

The disadvantage of these flowmeters is the need to introduce rods supporting the ultrasonic sensors and receivers into the stream, which, when they are large (~ 10-20), introduce uncontrolled disturbances into the stream. In addition, the small amplitudes of the receiving signals and their small transit times from the emitter to the receiver impose high requirements on the electronics that register them.

Also known are devices for detecting gas-liquid flows using resonators in the microwave and extra-high frequency ranges, based on a change in the electrodynamic characteristics of the resonators as the well production products pass through them [5, 6, 7]. The device [5] uses the effect of the reaction of an open cylindrical resonator on a perturbation body that enters the region occupied by the resonator field under the influence of aerodynamic pressure and is designed to record low speeds or costs.

The device [6] also implements the principle of sensing the flow, but using waves of the decimeter range. It is a closed resonator whose diameter exceeds the diameter of a standard pipeline; the resonator runs on

TM ₀₁₀ type of oscillation in the frequency range ~ 1 GHz. To withstand high pressures in a standard pipeline, the resonator is housed in a special power housing and is designed as a separate measuring section.

However, the transition to such a resonator caused a deterioration in sensitivity: the region of low water contents (~ 10-50 cm ³ / m ³ ) began to be recorded with low accuracy. In addition, the placement of the decimeter wave resonator in a separate power package significantly increases the cost of the measuring section. This is a disadvantage of the device [6].

Closest to the proposed measuring section is the device described in the patent [7], which we will take as a prototype.

The device [7], which implements the principle of sensing the flow using electromagnetic waves of small (~ 8 mm) wavelength, is a narrowing device such as a Venturi nozzle, inside of which there are two concave mirrors of the Fabry-Perot microwave resonator, which radiates through the entire cross section of the gas-liquid flow. In addition, the transition from the standard narrowing to the measuring section is made in the form of a conical narrowing with a corrugated side surface and an annular protrusion. The flow rate is measured by a Doppler speed meter by shifting the frequency of the radio wave of the 8 mm range from the dropping liquid aerosol moving with the gas velocity.

The considered device has the following disadvantages.

1. Gas-liquid flow at high speed (~ 20-60 m / s), passing the region of the microwave cavity, due to the presence of concave mirrors in the cylindrical channel of the constricting device and the insert located there in the form of ribs of a triangular profile (installed for selection of non-working types of vibrations ) experiences a sharp change in geometry, which leads to the appearance of aerodynamic vortices and aerodynamic instability of the flow as a whole. The presence of a corrugated cone at the beginning of the narrowing device and the annular protrusion leads to the same. The consequence of this is the sharply turbulent nature of the flow in the measuring channel, which leads to a significant scatter in the readings of the density sensor and the need for a large set of statistics.

2. Due to the high sensitivity to water, the upper boundary of the water-gas factor - water-rich water (the number of cm ^{3 of} water in one m ^{3 of} gas under standard conditions) lies in the region of <100 cm ³ / m ³ , which is not enough when working with wells subjected to flooding (VGF> 100 cm ³ / m ³ ). When VGF> 100 cm ³ / m ^{3 the} density sensor reaches the upper limit of the operating range, the signal from it drops to the noise level.

The technical problem solved in the proposed device is the ability to measure VHF in the range of both small values (10-100 cm ³ / m ³ ) and large values (VGF ~ 100-1000 cm ³ / m ³ ), shortening the measurement time and decreasing cost of the diagnostic section.

These technical results are achieved by the fact that in the measuring section of the gas-liquid flow meter, consisting of a plot for measuring small VHF based on a millimeter wave resonator, a plot for measuring flow velocity and a plot for measuring large VHF based on a closed decimeter wave resonator, all three measuring sections are combined into one design - measuring channel, an open cylindrical resonator (OCR) is used as a millimeter wave resonator; the shape of the measuring channel through which the gas-liquid flow passes is made the same throughout the entire length of the measuring section: it is cylindrical and its diameter is equal to the internal diameter of the OCR, and the conjugations of the standard pipeline with the measuring channel are smooth with a gradual and smooth transition from one diameter to another and with by polishing both the transitions themselves and the inner diameter of the channel, and the outer diameter of the closed cylindrical decimeter wave resonator is made equal to or less than the inner diameter orpusa measuring section.

As a result of the fact that the measuring channel is made single-row and has polished walls and smooth transitions from the pipeline to the channel and vice versa, the gas-liquid flow does not experience noticeable resistance, this helps to stabilize its position in space and leads to the fact that there is no need to collect statistics when registering it parameters - speed and density, and parameters of diagnostic resonators.

EFFECT: absence of a power case for a closed decimeter wave resonator is achieved by varying the shape of the resonator and the dielectric constant of the dielectric filling it, it was possible to reduce the outer diameter of the resonator, which allowed the cavity to be inserted inside the measuring section and to abandon the special power case.

The drawing shows a diagram of the measuring section. On it are indicated: 1 - measuring section, made on the basis of a standard pipeline; 2 - its connecting flanges; 3 - smooth transition from a standard pipeline to a measuring channel; 4 - wall of the measuring channel; 5 - plot of the measuring channel, where the small-scale VHF measurement takes place; 6 - open cylindrical resonator (OCR), operating in the millimeter wavelength range; 7 - a waveguide for coupling the OCR to the EHF generator; 8 - a waveguide for coupling the OCR with an EHF detector; 9 - connecting flanges; 10 - radiotransparent window for input / output of millimeter radiation in the center; 11 is a plot of the measuring channel, where the flow velocity is measured; 12 - transceiver antenna of the Doppler speed meter; 13 - radiotransparent window for input / output of probing radiation of the speed sensor; 14 - a connecting flange; 15 - section of the measuring channel, where the measurement of large VGF; 16 - enclosure of a closed cylindrical resonator (ZCR) decimeter waves; 17 - communication cable ZCR with a microwave generator; 18 - communication cable ZCR with a microwave detector; 19 - bushing insulators; 20 - dielectric with a large dielectric constant.

разThe operation of the device is as follows. The gas-liquid flow flowing through the pipeline smoothly enters the measuring channel, while its speed increases in

time

выбирают в границах 2-3, так что скорость возрастает в 4-10 раз, достигая 20-80 м/с. (Стараются подобрать это соотношение таким образом, чтобы скорость газа при средних расходах газа составляла ~50 м/с). При такой скорости пленка жидкости с поверхности трубы и полированных переходов срывается и переходит в аэрозоль. Газожидкостный поток проходит через ОЦР; при этом измеряется смещение его частоты Δω₁ и изменение добротности

. На участке между ОЦР и ЗЦР измеряют доплеровский сдвиг частоты Δf₀. Далее поток проходит через ЗЦР, где также измеряется сдвиг его частоты Δω₂ и изменение добротности

. Эти данные поступают в электронно-вычислительное устройство (не показано), где используя алгоритмы, описанные в [6] и [7], находят расходы газа Q_г, углеводородного конденсата Q_к, воды Q_в и вычисляют водогазовый, конденсатогазовый факторы (ВГФ, КГФ).(and ₁ is the diameter of the standard pipeline, and ₂ is the diameter of the measuring channel). Ratio

choose between 2-3, so the speed increases by 4-10 times, reaching 20-80 m / s. (They try to choose this ratio so that the gas velocity at an average gas flow rate of ~ 50 m / s). At this speed, the liquid film from the surface of the pipe and polished transitions breaks off and passes into an aerosol. The gas-liquid flow passes through the CRO; in this case, a shift of its frequency Δω ₁ and a change in the quality factor are measured

. In the section between the center-closed center and the center-center, the Doppler frequency shift Δf _{0 is} measured. Further, the flow passes through the ZCR, where the shift of its frequency Δω ₂ and the change in the quality factor are also measured

. These data go to an electronic computing device (not shown), where, using the algorithms described in [6] and [7], they find the flow rates of gas Q _g , hydrocarbon condensate Q _k , water Q _c and calculate the gas-water, gas-condensate factors (VGF, KGF).

A prototype device was tested in laboratory conditions on gas-liquid mixtures; compressed gas from cylinders was used as gas at pressures from 1 to 10 atm and a temperature of 10-25 ° C; as a liquid, water and an oil-water emulsion.

The experiments performed have confirmed a significantly higher level of stability of the measuring section. When working with small HCFs (1-50 cm ³ / m ³ ), data on the density of the gas-liquid mixture came from both resonators OCR and ZCR (the latter was at the beginning of the operating range); at large VGF (100-1000 cm ³ / m ³ ), the readings were taken only from the CCR, since the signal from the CCR due to the large attenuation was not recorded.

Thus, the full range of measurement of the hepatitis A was from ~ 1 to 1000 cm ³ / m ³ .

Literature

1. US patent US 1155389883, G01N 022/04, from 14.02.1995. Measure-ment of gas and water antentinoil. Posted by Harper R.

2. Patent 2393727 Canada, Intem. C1 Golf 1/74, dated 05.03.01. Simultaneos determination of multiphase flowrates and concentration from 03/05/01. Melnikov V., Drobkov V., Shustov A.

3. RF patent 2126143, MKH G01F 1/74. Ultrasonic flowmeter of components of a multiphase medium. / V.I. Melnikov, V.P. Drobkov, A.V. Shustov.

4. Drobkov V.P. Development and research of ultrasonic methods and information-measuring system for measuring the flow of oil and gas flow. Abstract for the degree of Doctor of Technical Sciences

5. RF patent №2286546 C2, dated 23.11.2004. Method and device for measuring gas-liquid flow rate. / Embroidered I.G., Kostyukov V.E., Moskalev I.N. and etc.

6. RF patent No. 2289808 dated 12/20/2006. Method and device for determining volume fractions of liquid hydrocarbon condensate and water in a stream of a gas-liquid mixture of natural gas. / Embroidered I.G., Kostyukov V.E., Moskalev I.N. and etc.

7. RF patent №2164340 dated 03.20.2001. A method for determining the component flow rate of a gas-liquid mixture of gas and oil products in a pipeline and a device for its implementation. / Orekhov Yu.I., Moskalev I.N., Kostyukov V.E. and etc.

Claims (2)

1. The measuring section of the gas-liquid flow meter, consisting of a plot for measuring small water-gas factors (VGF) based on a millimeter wave resonator, a plot for measuring flow velocity and a plot for measuring large VGF based on a closed decimeter wave resonator, characterized in that all three measuring sections are combined into one design - a measuring channel, an open cylindrical resonator (OCR) is used as a millimeter wave resonator, the shape of the measuring channel through which the gas-liquid passes the rest of the flow is made the same throughout the entire length of the measuring section: it is cylindrical and its diameter is equal to the internal diameter of the OCR, and the conjugations of the standard pipeline with the measuring channel are smooth with a gradual and smooth transition from one diameter to another and polishing both the transitions and the inner diameter of the channel. 2. The measuring section according to claim 1, characterized in that the outer diameter of the closed cylindrical resonator is made equal to or less than the inner diameter of the housing of the measuring section.