Pressure drop of variable mass flow in perforation completion of horizontal wellbore

There are many factors that affect the productivity of horizontal wells and the inflow profile of directional wells,one of which is the pressure drop along the path of horizontal wellbore.Based on the practice of horizontal wellbore production and Daqing multiphase flow test loop,a test section of wall injection system and variable mass flow is designed.Single-phase and two-phase variable flow experiments are conducted to research the variable mass flowing rule of perforated horizontal wells.Research results show that the pressure drop along the path of the single-phase horizontal wellbore changes with the injection ratio and there is a critical injection ratio.When the injection ratio surpasses the critical injection ratio,pressure drop increases dramatically.The cause is illustrated with further numerical simulation research.When the injection ratio exceeds the critical injection ratio,flow separation occurs nearby the perforation,as well as the mixing pressure drop works.As a result,the pressure drop rises dramatically.Besides the injection ratio,the two-phase oil/water variable flow is influenced by the change of water percentage.Under high flow conditions,the pressure drop is the highest when the water percentage is 40%,as well as the flow pattern is dispersed.Under low flow conditions,the pressure drop changes little with the water percentage,as well as the flow pattern is stratified.The research result may be a good reference to well completion design.