Development of a Transient, Multi-Feed Geothermal Wellbore Simulator

Abstract

Simulation of the flow in a geothermal wellbore is an important reservoir engineering task, but most existing geothermal wellbore simulators can only deal with steady-state conditions. This paper discusses the theoretical background of a transient geothermal wellbore model that is currently under development. The simulator is capable of modelling transient single and two-phase flow in wells with multiple feed-zones. A geothermal wellbore simulator solves the conservation of mass, momentum and energy equations governing the flow in a geothermal wellbore. These, along with the additional equations required for model closure, are presented. These governing equations are discretised and solved numerically using the Newton-Raphson procedure. The simulator is tested using analytical solutions for simplified single-phase flow situations. Steady-state validation cases are presented for both single-feed and multi-feed wellbores and a simulation of the transient behaviour of a geothermal production well is presented as a test case. Finally, further applications of the simulator are discussed.