Forecast of Injectivity for a Well with a Constant Bottomhole Pressure

Abstract

A semi-theoretical equation is used to approximate the dimensionless flow rate. This equation is utilized to forecast the injection fluid rate for a well with a constant bottomhole pressure (BHP). The advantage of fluid injection at BHP is that fluid injection can be easily controlled (at constant flow rate injection the BHP and wellhead pressure are changing with time). It was observed that during long term reinjection of water into geothermal reservoirs the well injectivity decreases as result of formation damage. To evaluate the skin factor in these cases a new method is proposed. It is assumed that the instantaneous injection flow rate and time data are available for a test at a constant bottomhole pressure. A simulated example of forecasting the injection flow rate for four values of the skin fhctor is presented.