Summary of Hot-Dry-Rock Geothermal Reservoir Testing 1978-1980

Abstract

Abstract Experimental results and reevaluate the Phase I Hot Dry Rock Geothermal Energy reservoir s at the Fenton Hill fields ite are summarized. This report traces reservoir growth as demonstrated during Run Segments 2 through 5 (January 1978 to December 1980). Reservoir growth was caused not only by pressurization and hydraulic fracturing, but also by heat extraction and thermal contraction effects. Reservoir heat- transfer area grew from 8000 to 50 000 m2 and reservoir fracture volume grew from 11 to 2663m. Despite this reservoir growth, the water loss rate increased only 30%, under similar pressure environments. For comparable temperature and pressure conditions, the flow impedance (a measure of the resistance to circulation of water through the reservoir ) remained essentiallyunchanged, and if reproduced in the Phase I1 reservoir under development, could result in "self pumping." Geochemical and seismic hazards have been nonexistent in the Phase I reservoirs. The produced water is relatively low in total dissolved solids and shows little tendency for corrosion or scaling. The largest microearthquake associated with heat extraction measures less than -1 on the extrapolated Richter scale.