Preliminary Review: Production Decline Anomaly in Reservoir Dry Steam, Patuha Geothermal Field Indonesia

Abstract

An abnormal production decline in one of the production wells in Patuha Geothermal Field, PPL-7, has occurred since the beginning of production where the wellhead pressure (WHP) & steam rate versus time plot showed an extreme slope of the regression curve. There are two suspected factors causing this anomaly behavior: the low permeability issue and the calcite scaling in wellbore. Based on geological review and drilling evidence, PPL-7 penetrated the microdiorite dike and thin andesite layer which is predicted to cause low permeability rocks inside the reservoir drainage reservoir (Re). To overcome calcite scaling problem, chemical stimulation and mechanical cleaning have been performed: acidizing and high-pressure injection, to reduce skin at main feed zones. In order to maintain well production, well washing program periodically applied following the decline WHP profile. Even though the decline behavior is different after each well washing program, well washing program is selected as temporary solution during deep investigation process.