| Abstract |
As with other energy forms, assessment of the capacity and cost of a geothermal field suffers from a number of major uncertainties. These include field extent and temperature, permeability, presence of gases and other dissolved chemicals, reinjection costs, steam deliverability per well, and recharge rate. This paper assesses the exploration histories of all New Zealand and some overseas fields.. Effective strategies for coping with uncertainty, and reducing risk, are discussed, based on this experience. Exploration drilling patterns conditional on the results from previously drilled wells, are recommended. More important, because some uncer tainties, such as recharge, cannot be adequately determined, without some exploitation, a multi-staged construction of power stations is necessary to cope with the major economic risk of oversizing. |