Estimation of upcoming problems in Alaşehir geothermal field using a numerical reservoir model

Alaehir geothermal area located in Alaehir Graben, West Anatolia, is the latest target for geothermal field development in Turkey. Seven different operators are developing the power capacity in this geothermal field on a strictly competitive and largely confidential basis without the significant exchange of resource information among them. Currently, eleven binary and combined flash-binary geothermal power plants with widely changing power generation efficiency between plants produce from the same reservoir. In order to identify upcoming problems for the complex and aggressive geothermal exploitation in Alaehir Geothermal Field, a highly populated numerical reservoir model was developed in TOUGH2 using different data sources such as geology, geophysics, pressure transient tests, tracer test, and geochemistry. The real-time power data are retrieved from the transparency platform of the Turkish energy exchange. The geothermal fluid is withdrawn from the field at a total production rate of 12,600 tons per hour. There are more than 100 wells in the field. The flow rate and wellhead flowing pressure of wells in the field central are used for calibration. The flow rate of wells changes between 100 and 450 tons per hour. The numerical model results are compared with a Monte Carlo simulation results in the field. Numerical reservoir simulation showed that more than 270 MWe production is not supported by artesian flow which is in agreement with Monte Carlo simulation results. The pressure decline of the field was found 3 bar per year. Using this model, power supply capability of the field is discussed considering economic and physical reliability. The best solution for maximizing energy exploitation from the field was found to produce with unitized reservoir management