A Review of Worldwide Experience of Reinjection in Geothermal Fields

Abstract

Worldwide experiences of reinjection in 92 electric-power producing geothermal fields are reviewed. The study shows that: a reinjection plan should be developed as early as possible and it should be flexible i.e. it is likely to change with time. The optimum reinjection strategy for liquid dominated systems (hot water, low enthalpy two-phase, medium enthalpy two-phase) is likely to involve a mix of infield and outfield injection with the exact details dependent on the type of system and the geological structure. The infield reinjection provides pressure support and thus reduces drawdown and the potential for subsidence, whereas outfield reinjection reduces the risk of cold water returning to the production area. Deep reinjection reduces the risk of groundwater contamination and ground surface inflation. The proportion of infield to outfield reinjection their location (deep or shallow) is case specific and typically the infield reinjection rate will vary with time as part of the steam field management strategy.