| The fracture-cavity carbonate reservoir is rich in reserves and has broad prospects for mining.In order to improve the remaining oil recovery of the reservoir high reservoir,the oil is mixed by gas and water to increase the sweeping area and achieve the purpose of enhanced oil recovery.The two-phase flow in the gas-water mixed wellbore is complicated,the flow pattern of each well section is unclear,and the parameters such as downward flow pattern and pressure are not predicted,which brings great difficulties for the construction optimization design.At present,the two-phase flow research is mainly aimed at the rise of the gas-liquid two-phase lift state in the production process of oil and gas wells.There are few theoretical and experimental studies on the gas-liquid two-phase down-flow in the gas-water mixing process.We lack a relatively complete functional experimental device for simulating a gas-liquid two-phase down-flow.In this paper,based on the research of gas-liquid two-phase flow in laboratory,a set of gas-liquid two-phase down-flow simulation experimental device with relatively complete functions is established for the gas-liquid two-phase down-flow,and the experimental scheme is developed,and the following work is mainly carried out.(1)Data such as production and construction parameters and well structure of on-site gas-water mixed wells are compiled,combined with the main parameters of gas-liquid two-phase flow research(gas-liquid flow rate,surface tension and density,etc.),using Duns&Ros dimensionless speed as a method of similarity and geometric similarity,the number of experimental parameters is determined,which provides a basis for the design of subsequent instrumentation and the design of experimental scheme.(2)The functional development requirements of the experimental device are analyzed.According to the characteristics and experimental requirements of the parameters,the measurement methods of the experimental parameters and the optimal measuring instruments are selected according to the main parameters of gas-liquid two-phase downward pipe flow research.(3)On the basis of the original two-phase flow study,a gas-liquid two-phase down-tube experimental device with vertical section(4m),inclined section(3m)and horizontal section(4m)was built,and each pipe section was photographed by high-speed camera.Characteristic flow pattern and its changing law,use the fast closing valve method to measure the liquid holding rate of each pipe section,and use the paperless recorder to collect and record the experimental parameters such as pressure and flow in real time.At the same time,the experimental safety operation rules applicable to the experimental device and the maintenance and repair methods of each instrument are developed.(4)According to the actual construction conditions and the range of parameters after similar conversion,a reasonable experimental scheme was designed.With air and water as the experimental medium,a total of 280 sets of experiments were carried out under four tilt angles and different gas-liquid flow rates,and the gas-liquid two were summarized.The characteristic flow pattern observed in the downward tube flow simulation experiment is compared and analyzed.The influence of the main factors of the flow pattern change(inclination angle,gas-liquid flow)on the characteristic flow pattern is analyzed.In this paper,the research on the construction of gas-liquid two-phase down-tube experimental device can provide data support for the subsequent theoretical research.The design ideas and schemes have certain reference for the construction of similar experimental devices. |
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