Application of Horizontal Well Completion Techniques to Enhanced Geothermal Systems: Final Report; October 2015 - September 2016

The petroleum industry has had success in developing unconventional shale plays using horizontal drilling and multi-zonal isolation and stimulation techniques to fracture tight formations, thus enabling the commercial production of oil and gas. Wellbore similarity exists with enhanced geothermal system (EGS) proposals. The technologies and techniques from the petroleum industry are being stretched to accommodate the higher temperatures, high water flow rates, and large-diameter completions encountered in geothermal settings. In this study, we assess whether well completion techniques used in the unconventional shale industry to create multi-stage fractures can be applied to an enhanced geothermal system, focusing on the fracture construction and completion of the EGS production well. We reviewed technologies used in these systems to determine if commercially available equipment from the petroleum industry could be used at the temperatures, pressures, and sizes encountered in geothermal settings. Our study found no major technical barriers to employing shale gas multi-zonal completion techniques in a horizontal well in a geothermal setting for EGS development. Temperature limitations of equipment are a concern for all techniques considered. Equipment designed to operate at high temperatures encountered in geothermal systems is commercially available, but is generally unproven for geothermal applications. Based on our study, further evaluation is warranted on adapting oil and gas completion techniques to EGS. This project is a continuation of the FY14 Horizontal Geothermal Completion project sponsored by the U.S. Department of Energy through the National Renewable Energy Laboratory and the Colorado School of Mines.