| The serious sand production in horizontal wells of sandstone heavy oil is a common problem in the reservoirs mining process.The sand in the wellbore is deposited at the bottom of the pipeline,causing friction between the pipeline and the equipment.When the sand particles turn into sand bed,it will affect the mining rate.In severe cases,the oil well will stop production.The sand particles of oil layer are carried to the ground by the foam fluid as a sand washing liquid.The design of foam generator's structure is a key device of developing foam,but there are currently few foam generators which suitable for oil wells.Based on the foam generation mechanism and the situation of heavy oil reservoirs,the design idea of disturbing foam generator with multi-baffle was proposed,and analyze the performance of the foam generator,which provides a powerful technical support for the work of loose sandstone resevoirs and sand washing in old oil field in low pressure.Firstly,according to the characteristics of the small working space and application conditions of heavy oil reservoirs in horizontal wells,the foam generator with disturbing device of multi-baffle was designed,combined with the principle of the venturi device and the baffle eddy current disturbance to improve foam stability.Secondly,through numerical simulation analyzed multi-baffle disturbing foam generator and optimized key structural parameters,such as the baffle angle,the baffle density and the baffle spacing.The results indicated that the larger the angle of the baffle inside,the better the gas-liquid mixing effect in the foam generator,and the more severe the current disturbance,the higher the bubble content of the mixing chamber,the better the foaming effect.A stable foam flow can be formed when the structure of the baffles is arranged at equal intervals.Therefore,the foam generator achieved its best performance with the baffle angle of 90°and the baffle distance was L=50 mm,the volume distribution of the gas phase in the mixing chamber was uniform and the velocity was large,which is favorable for generating a large number of dense and stable foam.Finally,through the experimental research on factors affecting the foaming performance of the foam generator,obtained that the lager the gas and liquid flow rate,the lager the foam flow rate,the gas inlet pressure and the concentration of foaming agent reached a certain level,then the foam flow did not change much.When the liquid flow rate is 22 L/min,the gas flow rate is 30 m~3/h,the gas inlet pressure is 1 engineering pressure,and the concentration of 1%,the foam flow reaches the maximum value of 621 L/min.In addition,the paper conducted a experimental study on the change of foam flow rate under the different angle pipelines,when the pipeline was close to horizontal,the pipeline angle ranges from 85°to 90°,the rate of foam flow was large and stable.The results of the above research,which provided a powerful theoretical support for gas-liquid two-phase flow research and optimization of foam generator structure,were significant to instruct field application. |
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