Crude oil-natural gas-water three-phase flow meter and its measuring method

Abstract

A three-phase flow meter of crude oil-natural gas-water is prepared as forming two paths at device inlet after flow pattern collator, setting one path in sequence with pressure transmitter, vortex precession flow meter, temperature transmitter and gas-liquid drag balance valve connected in parallel; setting another path in sequence with inverted ''U '' form tube, water content sampling and analyzing device, static mixer and Venturi tube.

Description

1. Technical field [0001] The invention relates to a crude oil-natural gas-water three-phase flow meter and a measuring method thereof. 2. Background technology [0002] With the development of oilfield mining and gathering and transportation technology, especially since the late 1990s, the demand for three-phase flowmeters of crude oil-natural gas-water in oilfields has become increasingly urgent, especially in the development of offshore oilfields. There are more urgent needs. At present, the three-phase flowmeter mainly uses the Venturi tube to measure the three-phase total flow, and the gamma ray to measure the phase ratio (gas-liquid ratio and oil-water ratio). Because this method uses γ-rays, it has high requirements for safety protection, which greatly limits the scope of use of this type of product, and when γ-rays are used to measure the water content (oil-water ratio), the density of oil and water is used as a characteristic quantity. The difference in water dens...

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Problems solved by technology

Because this method uses γ-rays, it has high requirements for safety protection, which greatly limits the scope of use of this type of product, and when γ-rays are used to measure the water content (oil-water ratio), the density of oil and water is used as a characteristic quantity. The difference in water density is used to measure the water content. Since the density of oil and water is relatively close (the density ratio is 0.83:1 to 0.93:1), the accuracy is limited, especially in the state of heavy oil (its density is more than 90% of water) It is difficult to accurately measure the moisture content when

In addition, the dielectric constant is used as the characteristic quantity, and the water content is measured by the capacitance method. Although this method avoids the safety problems caused by gamma rays, and the difference between the dielectric constants of oil and water is very large, oil and water can be easily distinguished. However, the dielectric constant of water is greatly affected by the degree of salinity, which greatly affects the measurement accuracy.

According to the principle of heat transfer, the thermal conductivity of oil and water is used as a characteristic quantity to measure the water content, but this method is affected by the viscosity change of oil (the viscosity of oil changes greatly with temperature), and due to the flow and heat transfer process Complexity (currently all rely on empirical formulas to calculate the heat transfer process), its range is limited, and the complexity of the debugging process limits the application. It is seriously affected by the flow pattern, especially when the flow pattern is annular flow, it is difficult to accurately measure the gas-liquid ratio, and the debugging is more complicated

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