Numerical Analysis And Experimental Validation Of Two-phase Flow In A Downhole Venturi Meter

After oil well is used for production, the mixing proportion of mixture of oil, water and g-as in this well will vary dynamically with mining process. The flow data located undergroundis an important foundation to indentify, determine the capacity abnormal spot and match prod-uction. The multiphase flowmeter can measure multiphase flow parameters online real-time,which is important for adjusting the oil well production process to adapt to current oil well sta-tus, and ensuring stable oil well production.In this thesis, combination of numerical simulation and the mature single-phase flow met-er-venturi flowmeter are applied to get the Phase Rate Model and achieve the measurement ofwater-oil two phase flowparameters. Due to the venturi flowmeter owns numerous advantage-s such as simple structure and easy installation, it is deeply studied on many application occasions, however, there is rare research related to liquid-liquid two phase flow of venturi pipe based on CFD. The main contents of this thesis are summarized as follows:(1)Three structure schemes of venturi pipe are designed, the unstructured tetrahedron gridfor them are meshed. Numerical simulation are carried out on condition of a variety of flow r-ate and oil-water ratio on ANSYS-CFX platform, and the computed results are analyzed as fo-llows: velocity of oil phase and water phase reach maximum in the throat and apparent velocity of them are equivalent numerically; pressure falls to lowest in the throat, which may causecavitation, the pressure difference between inlet and throat increases with the increase ofmixture viscosity; the power relationship between differential pressure and flow is furtherstudied, the differential pressure is that the different between inlet pressure and throat; phaserate, namely relation among water-oil ratio, flow and pressure difference, is drew. By compre-hensive consideration, optimal scheme is selected from the three schemes mentioned above.(2)Make experimental research of the venturi pipe, and comparison of simulation resul-ts,theoretical results and the experimental results. The result shows that simulation results ar-e almost equal to experimental results, which verified accuracy and feasibility of the model.(3)Based on replication experiment, the influence for measurement performance of water-oil two phase flow of venturi pipe caused by structure of venturi pipe is further researched. Inthe case of fixed pipe diameter, with no changing inlet diameter of venturi pipe, measurementsensitivity of venturi pipe’s flow can be improved by changing throat diameter ratio, and it represents that the measurement is influenced more significant with decrease during lowthroat diameter ratio. Due to numerous advantages of flow pipe, the influenced for measurement performance of venturi pipe’s flow caused by rectangular section is researched, the result i n-dicates that differential pressure increases with decrease of the inlet section area, meanwhile, measurement sensitivity of flow increases and resistance losses increases.