Success In Geothermal Development

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Journal Article: Success In Geothermal Development

Success in geothermal development can be defined as the ability to produce geothermal energy at compatible energy prices to other energy sources. Drilling comprises usually the largest cost in geothermal development, and the results of drilling is largely influencing the final price of geothermal energy. For 29 geothermal fields with operating power plants, the ratio between installed capacity and the total number of wells in the field is 1.90 MWe/well. The drilling history in 30 geothermal fields are analysed by plotting the average cumulative well outputs as function of the number of wells drilled in the field. The range of the average well output is 1-10 MWe/well with the mean value 4.2 MWe/well for the 30 geothermal fields studied. A learning curve is defined as the number of wells drilled in each field before the average output per well reaches a fairly constant value, which is characteristic for the geothermal reservoir. The range for this learning time is 4-36 wells and the average is 13 wells. In general, the average well output in a given field is fairly constant after some 10-20 wells has been drilled in the field. The asymtotic average well output is considered to be a reservoir parameter when it is normalized to the average drilling depth. In average, this reservoir parameter can be expressed as 3.3 MWe per drilled km for the 30 geothermal fields studied. The lifetime of the resource or the depletion time of the geothermal reservoir should also be considered as a parameter influencing the success of geothermal development. Stepwise development, where the reservoir response to the utilization for the first step is used to determine the timing of the installment of the next step, is considered to be an appropritate method to minimize the risk for overinvestment in a geothermal field.

Valgardur Stefansson

Published Journal 
Geothermics, Date Not Provided

Not Provided
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Valgardur Stefansson. . Success In Geothermal Development. Geothermics. (!) .