Numerical Model of Transient Steam-Water Two-Phase Flow in Geothermal Production Wells

Abstract

Geothermal production wells sometimes show fluctuation of wellhead pressure and flow rate when they are completed with multiple feed zones. This instability of the production leads to important problems for power plant operation such as a lack in steam supply and an unstable turbine inlet pressure. In the worst case it may lead to a stoppage of steam production. Its mechanism, however, is not well understood. In this study, we developed a numerical model of transient steam-water two-phase flow in a geothermal production well. This wellbore model is coupled with the reservoir model so we can treat the flow rate change with time from the reservoir into the wellbore and also deal with a well with multiple feed zones. We use a homogeneous model for wellbore flow and the related conservation equations. We present results of numerical simulations to demonstrate the capabilities of the techniques.