Injection Rehabilitation at Kizildere Geothermal Field: Use of Flow Rate Weighted Average Production Wellhead Pressure for Reservoir Management

Abstract

By commissioning of Kizildere-III geothermal power plant (GPP), an additional 165 MWe put on production, thus total installed power plants’ capacity operating by Zorlu Energy reached 260 MWe in Kizildere geothermal field, in 2018. Tripled production from the field created substantial changes in the reservoir dynamics. Although new production wells are located at the outer part of the existing production zone, such an increase in the total depletion rate needed to be treated accordingly. For this reason, before the commissioning of the Kizildere-III GPP, several wells that are located at inner and outer parts of the planned production zone, used as observation wells to quantify the effects of the depletion created by new production wells. After a while of production, a gradual pressure decline was monitored at all the observation wells and wellhead producing pressures. To identify the exact reason for the decline, a comprehensive tracer test was designed and implemented for the new injection wells. The tracer test showed that pressure support from the existing injection wells to Kizildere-III production wells would not be sufficient at the current operating conditions. With this diagnose, an injection rehabilitation plan was immediately adopted and implemented in the field. It was found that the new reinjection strategy provides good pressure support and the pressure decline rate is in the acceptable ranges. In this study, we present a practical approach that was used to identify new candidate wells for reinjection. Correlation of flow rate weighted average wellhead pressure with reservoir pressure was used to identify hydraulic connection between wells.