| Abstract |
With an increasing demand for renewable energy, dispatchable geothermal power presents a reliable solution to balance intermittent solar and wind generation. Enhanced geothermal systems (EGS) are a robust solution as they are applicable in a greater range of locations compared to traditional geothermal systems. Granite, a silica rich rock, is a common target layer for EGS given the depth necessary to reach the target reservoir temperature. With the cyclical changes in pressure and temperature during dispatchable production, the near wellbore area is prone to silica scaling, requiring costly interventions if not adequately predicted. This paper addresses the effects of silica scaling in the near wellbore area during dispatchable production for EGS. A transient reservoir model using Eclipse to couple thermal and pressure cycling and their effects on the geochemistry of the geofluid was established. The model solves time-dependent flow and heat transport equations to capture transient behaviour. It was applied to various dispatchable scenarios with varying production to assess the effect of the silica precipitation. The simulation revealed that silica scaling in granite reservoirs cannot be neglected in dispatchable EGS. Specific timeframes and operational thresholds were identified to prevent drastic remediation methods that require shut ins of the wells. This study offers one of the first dispatchable EGS modelling approaches to account for silica scaling during operations. Actionable insights and operational thresholds are defined, improving reliability and reducing downtime in future dispatchable geothermal energy developments. |