| Title | Implications of Drilling Technology Improvements on the Availability of Exploitable EGS Resources |
|---|---|
| Authors | Thomas S. LOWRY, Adam FORIS, John T. FINGER, Stephen PYE, Douglas A. BLANKENSHIP |
| Year | 2017 |
| Conference | Stanford Geothermal Workshop |
| Keywords | Drilling costs, enhanced geothermal systems, EGS, LCOE, GT-Mod, GeoVision |
| Abstract | This study uses an inverse modeling approach to quantify how improvements in technologies that reduce well drilling costs can increase the national occurrence of economically viable EGS sites. To provide context to the potential technology improvements, we group well costs into four general categories; 1) drilling costs, 2) non-drilling costs, 3) trouble time, and 4) additional time. Results from the DOE’s GeoVision study has produced four cost curves for geothermal well drilling that describe the drilling cost as a function of depth with each curve representing a different level of technology that helps reduce drilling costs. This study examines how those advances in drilling technology can change the spatial area where EGS can be economically exploitable. To do this, we simulate a hypothetical 50 MW EGS system with an initial reservoir temperature of 200 oC and then calculate the drilling costs required to achieve LCOE’s of 8, 10, 12, 14, and 16 ¢/kW-hr. The costs curves are used to calculate the attainable depth for each required cost. The attainable depths are then cross-referenced against the SMU temperature-at-depth maps to determine the economically exploitable area for each cost curve and LCOE. Results show that LCOE’s of 8 and 10 ¢/kW-hr are nearly unattainable without other cost reductions; however 10 ¢/kW-hr is attainable for the Ideal case for depths of 3400 m. At higher LCOE’s, the exploitable area increases exponentially above a threshold as a function of the decrease in drilling costs. |