Void Fraction Measurement of Oil-Gas-Water Three-Phase Flow Using Mutually Perpendicular Ultrasonic Sensor

Flow Pattern Identification of Oil-Water Two-Phase Flow Based on SVM Using Ultrasonic Testing Method

A flow pattern identification method combining ultrasonic transmission attenuation with an ultrasonic reflection echo is proposed for oil-water two-phase flow in horizontal pipelines. Based on the finite element method, two-dimensional geometric simulation models of typical oil-water two-phase flow patterns are established, using multiphysics coupling simulation technology. An ultrasonic transducer test system of a horizontal pipeline with an inner 50 mm diameter was built, and flow pattern simulation experiments of oil-water two-phase flow were carried out in the tested field area. The simulation results show that the ultrasonic attenuation coefficient is extracted to identify the W/O&O/W dispersion flow using the ultrasonic transmission attenuation method, and the identification accuracy is 100%. By comparison, using the ultrasonic reflection echo method, the echo duration is extracted as an input feature vector of support vector machine (SVM), and the identification accuracy of the stratified flow and dispersed flow is 95.45%. It was proven that the method of the ultrasonic transmission attenuation principle combined with the ultrasonic reflection echo principle can identify oil-water two-phase flow patterns accurately and effectively, which provides a theoretical basis for the flow pattern identification of liquid-liquid multiphase flow.

Modelling of ultrasonic method for measuring gas holdup of Oil-Gas-Water three phase flows

In oil-gas-water three-phase flow, the presence of two physically distinct dispersed phases leads to complex interfacial effects and relative velocities between the phases, which poses a significant challenges for gas holdup measurements. In this paper, a novel gas holdup measurement based on flow structure detection is realized. Firstly, the effect of gas bubble diameter on ultrasonic attenuation was studied, and a gas bubble diameter-based ultrasonic gas holdup measurement model was proposed. According to the model's specifications, a combined measurement system consisting of pulse transmission ultrasonic sensor and bi-optical fiber probe sensor was built. The dynamic experiment of oil-gas-water three-phase flow was conducted on a simulated well installation to measure the gas holdup using the combined measurement system. The results suggest that the proposed ultrasonic-optical measurement system can attain a high level of measuring precision.

Behavior of the Free Surface of Two-Phase Fluid Flow Near the Taphole in a Tank

The present study numerically investigated the deformation of the free-surface of two-phase fluid flow in a tank which is considered as a simplified blast furnace hearth. Actually, the fluids existing in a blast furnace hearth are gas, slag and hot metal from top to bottom. However, the present study considered only gas and cold molten iron in the tank. The porosity is considered as a substitute for void volume formed by the packed bed of the particles such as cokes. The single-phase flow and two-phase fluids flow without the porosity are analyzed for comparison. The porosity contributed the free surface to forming a viscous finger near the taphole. The axi-symmetry nature of the interface of two-phase fluids flow in the cylindrical tank is broken by viscous finger as the interface instability by the gas entrainment into taphole, which has been identified by the visualization of the free surface formation. The acceleration of the free surface falling velocity and the outflow near the taphole are associated by the viscous finger by the gas entrainment. The dimensionless gas break-through time is linear with respect to the porosity magnitude.