Reinjection in geothermal fields: A review of worldwide experience

The worldwide experience of reinjection in geothermal fields is reviewed. Information from 91 electric-power producing geothermal fields shows that: a reinjection plan should be developed as early as possible in field development and it should be flexible as it is likely to change with time. The optimum reinjection strategy depends on the type of geothermal system. For vapour-dominated systems which can run out of water reinjection should be infield. While for hot water and liquid-dominated two-phase systems (low-enthalpy and medium-enthalpy) reinjection is likely to involve a mix of infield and outfield injection. In general 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 and the 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.