Preliminary Reservoir Design and Screening for a Commercial Hot Dry Rock Geothermal Prospect

Abstract

A preliminary commercial reservoir design was completed for a promising hot dry rock (HDR) prospect in central Utah. The conceptual design included well trajectory plans, well designs, and a novel completions approach for creating the multilevel subsurface reservoir. Modeling results obtained early in the study emphasized the economical importance of creating a large heat transfer area per well pair and maximizing the target temperature consistent with technical constraints. The investigation adhered to the following ground rules concerning technology: (1) Currently available geological, geophysical, and reservoir production data were used; no additional geotechnical field work was performed, and (2) Current technology or reasonable extensions were used of well and reservoir designs. These ground rules limited the technology base to the current state of the art so that commercial development can proceed if the project economics are favorable and the technical risks are acceptable. In addition, use of these ground rule emphasized some important technology gaps for which additional HDR data are needed before expected project performance and economics can be adequately evaluated.