Identifying Important Reservoir Characteristics Using Calibrated Wellbore Hydraulic Models in the Salak Geothermal Field, Indonesia

Abstract

The performance of production wells in the Salak geothermal field is routinely evaluated using wellbore hydraulic models that have been calibrated to match the 15 year production history of each well. The calibrated models accurately represent well geometry, the location and productivity index of each permeable zone, and the historical evolution of pressure and enthalpy at each zone. The models are normally used to forecast the deliverability of individual wells as reservoir conditions continue to evolve. However, during the calibration process it is also possible to identify well and reservoir characteristics that are not apparent in production trends or downhole surveys. For example, evidences of scale deposition, the influx of cooler fluids, and interzonal flow were identified during calibration. In several wells; these phenomena were subsequently confirmed through more detailed well surveillance. The calibrated wellbore models were found to be accurate tools for forecasting steam and brine production over the medium term and powerful tools for diagnosing well performance issues and focusing surveillance efforts.