Reinjection Management in Balcova Geothermal Field

Abstract

Balcova geothermal system, which has two concealed out flow zones at 40-100 m (shallow) and 300-700 m (deep), is a defined fracture zone system. The temperature of the production wells is changing between 100 and 140oC. A district heating system has been operating since 1996. A large scale reinjection was applied to shallow zones up to 2001. Tracer and monitoring studies showed that reinjection to shallow zones is not efficient, causing environmental problems and severe cooling at shallow zones of the field. Thus, reinjection strategy has been changed. The main principles of the new reinjection strategy are: (1) reinjection is an integral part of the geothermal reservoir management, (2) full scale reinjection is needed for producing much energy, sustaining geothermal reservoir and environment properly, (3) new reinjection wells must be placed on the margins of the Balcova field, (4) effect of the new management strategy on the field must be monitored. For two years, half of the produced water has been reinjected in well BD8, in the eastern margin of the field. A new well, named BD10, is being drilled in the western margin, with the goal of reaching full scale reinjection target in the field.