Study on a Horizontal Well Productivity Equation

The pressure drawdown calculated with the calculation model in which wellbore pressure loss is considered is usually higher than it should be.Based on the study on the reservoir inflow performance with horizontal well wellbore couple flow and flow resistivity;and according to mass conservation law and permeable flow resistivity definition,the relationship between horizontal well wellbore pressure drawdown and production pressure drawdown is analyzed;and the prediction equation of steady state productivity of a horizontal well is derived by adopting the calculation of pressure loss stage by stage.The study shows that the main flow in a horizontal well is the inflow from reservoir to wellbore no matter it is at high speed or at low speed;and the flow at the toe takes on spherically radial flow.