A Middle-Term Power Output Prediction at the Hatchobaru Field by Coupling Multifeed Wellbore Simulator and Fluid-Gathering Pipeline Simulator to Reservoir Simulator

Abstract

A method has been developed to predict the response of a reservoir to exploitation using a new simulator that is the coupling of a reservoir simulator, a multi-feed wellbore simulator and a two-phase pipeline network simulator. This method was applied to the reservoir management of the Hatchobaru geothermal field in Kyushu, Japan. The operation of the three-coupled simulators was successfully tested. Results of a middle term forecasting of power output at the power plant indicated a constant power decline with the decline rate of about 4% per year due to the return of reinjected water into the production zones. The study on the problem using the newly developed simulation tool indicated that relocating the reinjection zone to the north of the field would mitigate the cooling of the production zones influenced by reinjection while maintaining pressure support to the reservoir. In the case of Hatchobaru the simulation results also indicated the need of drilling a make-up well every year for steadily maintaining the rated power output.