Advanced Drilling and Its Impact on Heat Mining

Abstract

Given today's energy prices and optimistic projections of abundant oil, gas, and coal supplies, a significant improvement in the reservoir development costs for heat mining in hot dry rock systems is needed before mid- to low-grade resources can be exploited for electric power production. Higher fluid productivity and/or lower well drilling costs are needed. This paper focuses on drilling technology requirements and possible new developments that could achieve substantial reductions in drilling costs. Such revolutionary change could shift the drilling cost versus depth relationship from its current exponential dependence to a more linear dependence. Improvements discussed include: systems integration with advanced "lookahead geophysical characterization of the rock coupled to online control of key drilling parameters, and advanced penetration concepts involving thermal spallation, erosion, and cavitation with and without coupling to rotary methods. A new national initiative on advanced drilling and excavation technology is reviewed as an example of what would catalyze the development of such improvements.