The Impact of High Noncondensible Gas Concentration on Well Performance: Kizildere Geothermal Reservoir, Turkey

Abstract

Noncondensible gas is a major factor affecting the reservoir pressure in the deep liquid-dominated Kizildere geothermal reservoir which is currently by developed by ZORLU ENDÜSTRİYEL VE ENERJİ TESİSLERİ İNŞ.TİC.A.Ş.(Zorlu Enerji) as the Kizildere II Geothermal Power Project. Under static conditions, the pressure within the production zone ranges from 130-230 bar. Temperatures are 220 to 240oC. Based on gas pressures estimated from applying Henry’s law constants, approximately 70 bar (at 0.024 kg NCG/kg reservoir brine) to 100 bar (at 0.030 kg NCG/kg reservoir brine) is dissolved noncondensible gas pressure. The noncondensible gas is over 98% carbon dioxide. The reservoir fluids at Kizildere are known to produce calcite scale in the wellbores at the depth of gas breakout. Given the high gas pressure, the gas breakout pressures (the pressure below which the fluid will begin transform from 100% liquid to two-phase) are between 80 bar (at 0.024 kg NCG/kg reservoir brine) and 100 bar (at 0.030 kg NCG/kg reservoir brine). At the flow rate (