A new computation model for pressure drop of variable mass flow in horizontal wells

Wellbore flow in horizontal wells can be divided into two categories, the constant mass flow and variable mass flow, depending on the presence or absence of inflow through wellbore wall. Investigations of the constant mass flow can provide experimental methods and lay a theoretical basis for researches of the variable mass flow model, which is widely used in coupling models for reservoir seepage with wellbore flow in horizontal wells, multi-stage hydraulic fractured horizontal wells and branched horizontal wells. The accuracy and rationality of the pressure drop model profoundly can influence the prediction of well productivity and production performance. Through the literature review and analysis of the previous models, we developed a new regression model capable of calculating friction factors and pressure drop during ceaseless variation of the shooting density and phasing degree in perforated completion. The results from the previous models and the new one were compared and discussed, which may provide reference for model selection of the variable mass flow and improve studies on coupling models of wellbore flow with reservoir seepage.