Reinjection in Geothermal Fields: A Worldwide Review Update

Abstract

Reinjection is a very important part of any geothermal development and it may become the key factor in the success or failure of the field. In 2010, we conducted a review of the worldwide experiences with injection in geothermal fields, based on information from 91 electric-power producing geothermal projects. In the present review, we have extended the database to include 126 field projects and added an additional five years of experience. In this updated review, various past and current reinjection strategies practised in the geothermal fields and the response of different types of geothermal reservoirs to these strategies were investigated. The location and amount of reinjection, as well as, problems and benefits associated with production were taken into consideration. This study shows that the design of reinjection is most often empirical and site-specific, because the effect of injection on production depends on the structure of the individual system. However, there are some generic similarities depending on whether the system is vapour-dominated, liquid dominated or hot-water. Experience has shown that reinjection should be planned as early as possible in field development and it should be flexible, as it is likely to change with time. An optimum reinjection design should balance the requirements to sustain the reservoir pressure and to prevent early breakthrough of cold reinjected water. Also, the effects of reinjection on the natural hot recharge and, therefore, on energy recovery from the system may be important.