RU2466356C1 - Method of measuring flow rate of two-phase three-component medium - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of measuring flow rate of two-phase three-component medium involves calibrating a multiphase flow metre, processing calibration results, synthesis of a mathematical model of the motion of the two-phase three-component medium, determining the flow interval of liquid and oil gas for which the permissible error in calculating flow rate of oil, water and oil gas holds. Calibration is carried out to obtain training experimental points. Several models of the motion of the two-phase three-component medium with different maximum errors when determining flow rate of liquid are synthesised. Calibration is carried out to obtain calibration experimental points, from which flow rate of liquid is calculated using the model of the motion of the two-phase three-component medium with different maximum errors. The model for calculating component-by-component flow rate of the two-phase three-component medium is selected based on the minimum absolute error on the calibration experimental points.

EFFECT: high accuracy of measuring flow rate of a two-phase three-component medium.

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Description

The invention relates to the oil industry, and in particular to methods for determining the production rate of oil wells without prior separation of gas from well products.

A known method for determining the content of components of a multiphase medium, including sounding a stream with acoustic pulses, recording pulses transmitted through a medium by a receiver in a limited controlled volume of a stream formed by a pair of "radiation source - receiver", fixing the time it takes for pulses to pass through a controlled volume, and calculating the flow rate of components based on the laws of motion two-phase three-component medium [1]. However, this method leads to significant errors in determining the flow rate of a two-phase medium due to the neglect of the effect of oil gas dissolved in oil and water at pressures and temperatures in the measured flow.

Closest to the proposed solution is a method of measuring the flow rate of a two-phase three-component medium, including calibrating a multiphase flow meter, processing the results of calibration work, synthesizing a mathematical model of the movement of a two-phase three-component medium, determining the interval of flow rates of liquid and oil gas, in which there is a permissible error in calculating the flow rates of oil and water and gas [2].

However, this method leads to errors in determining the component flow rate of oil well production due to the incorrect selection of a mathematical model for calculating the component flow rate.

The objective of the proposed technical solution is the development of such a method of measuring the flow rate of a two-phase three-component medium, in the implementation of which it would be possible to eliminate errors caused by the incorrect choice of the mathematical model of motion of a two-phase three-component medium.

The technical result of the invention is to increase the accuracy of measuring the flow rate of a two-phase three-component medium by selecting a mathematical model of motion of a two-phase three-component medium with a minimum average absolute error from an alternative list of models.

The technical result is achieved by the fact that in the method for measuring the flow rate of a two-phase three-component medium, including calibrating a multiphase flow meter, processing the results of calibration work, synthesizing a mathematical model of the movement of a two-phase three-component medium, determining the interval of flow rates of oil, water and oil gas, in which there is an allowable calculation error expenses of oil, water and oil gas, carry out calibration work to obtain training experimental points for training exp At the experimental points, a number of models are synthesized with various maximum errors in determining the fluid flow, carry out calibration work to obtain test experimental points, and test the fluid flow using test experimental points using motion models of a two-phase three-component medium with various maximum errors, and to minimize the average absolute error for test experimental points choose a mathematical model to calculate the component flow rate vuhfaznoy three-component medium.

The method is implemented as follows. A multiphase flow meter is calibrated to obtain training experimental points. In the table of calibration results for an acoustic Doppler flow meter, the liquid consumption corresponds to the readings of Doppler frequency shift, water cut, gas saturation, pressure and temperature sensors. Using these experimental data, a number of mathematical models of the motion of a two-phase three-component medium with various maximum errors are synthesized. Moreover, the number of models can vary from 5-6 to 8-10. The maximum error of the model synthesized based on training points can exceed the permissible error by a factor. By removing a number of points with a maximum error, the latter must be reduced to a value 2-3 times less than the permissible error. Thus, a number of models are synthesized. The first of them has the largest maximum error, the second, due to the removal of the point with the maximum error, has the maximum error with a smaller value. The third model has a maximum error with a smaller value compared to the second model. And the latest model has a maximum error of the lowest. Conduct calibration work to obtain test experimental points. Using these test points, using the readings of Doppler frequency shift, water cut, gas saturation, pressure and temperature sensors as input indicators, the liquid flow rate is determined using the above models. The error in determining the flow rate of liquid is fixed for models with various maximum errors. For the optimal model, take the one that has a minimum average absolute error at the test experimental points.

An example of a specific implementation of the method is illustrated by the materials of the results of the calibration work on the pouring installation of the UltraFlow device. Six models were synthesized from the training experimental points, the maximum error and standard deviation of which are given in the table.

Table Model one 2 3 four 5 6 Maximum absolute error 0.1157 0,0498 0,0406 0.0185 0.0113 0.0071 Standard deviation of error 0,0488 0.0260 0.0160 0.0069 0.0048 0.0039

Models have the form:

Y = b ₀ + b ₁ * X ₁ + b ₂ * X ₂ + b ₃ * X ₃ + b ₄ * X ₄ + b ₅ * X ₅ + b ₁₃ * X ₁ * X ₃ + b ₁₁ * X ₁ ² + b ₃₃ * X ₃ ² ,

where Y is the fluid flow rate;

X ₁ - Doppler frequency shift;

X ₂ - water cut well production;

X ₃ - gas saturation;

X ₄ - pressure in a controlled volume flow;

X ₅ - temperature in a controlled volume flow.

Using these models of motion of a two-phase three-component medium, fluid flow calculations were performed for eighteen test experimental points. The calculation results are shown in the drawing. As can be seen from this drawing, the fourth model has the smallest average absolute error. This model is recommended for calculating the component flow rate of oil well production.

The proposed technical solution will significantly reduce the error in determining the component flow rate of a two-phase three-component medium.

Information sources

1. RF patent No. 2138023 “Method for determining the flow rate of components of a multiphase medium. // Melnikov V.I., Drobkov V.P. - 1999.09.20.

2. Pismarov M.N. Calculation of the flow of a three-component medium during the calibration of a multiphase flow meter. Innovations and current problems of engineering and technology: materials of the All-Russian scientific and practical conference of young scientists in 2 volumes / M.N. Pismarov, K.Yu. Plesovskikh; under the editorship of A.A. Bolshakova. - Saratov: Saratov State Technical University, 2009. - T.1. - 360 p. - S. 110-112.

Claims (1)

A method of measuring the flow rate of a two-phase three-component medium, including calibrating a multiphase flow meter, processing the results of calibration work, synthesizing a mathematical model of the motion of a two-phase three-component medium, determining the interval of flow rates of liquid and oil gas, in which there is a permissible error in calculating the flow rates of oil, water and oil gas, characterized in that they carry out calibration work to obtain training experimental points, a number of the motion of a two-phase three-component medium with different maximum errors in determining the flow rate of the liquid, carry out calibration work to obtain test experimental points, from the test experimental points calculate the fluid flow rate using models of the movement of a two-phase three-component medium with different maximum errors, and at the minimum average absolute error for test experimental points choose a model for calculating the component flow rate of a two-phase rehkomponentnoy environment.