Development of a Hydrothermal Spallation Drilling System for EGS Geothermal Project

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Last modified on July 22, 2011.

Project Title Development of a Hydrothermal Spallation Drilling System for EGS
Project Type / Topic 1 Recovery Act: Enhanced Geothermal Systems Component Research and Development/Analysis
Project Type / Topic 2 Drilling Systems
Project Description Potter Drilling has recently demonstrated hydrothermal spallation drilling in the laboratory. Hydrothermal spallation drilling creates boreholes using a focused jet of superheated water, separating individual grains (“spalls”) from the rock surface without contact between the rock and the drill head. This process virtually eliminates the need for tripping. Previous tests of flame-jet spallation achieved ROP of 50 ft/hr and higher in hard rock with minimal wear on the drilling assembly, but operating this technology in an air-filled borehole created challenges related to cuttings transport and borehole stability. The Potter Drilling system uses a water based jet technology in a fluid-filled borehole and as a result has the potential to achieve similarly high ROP that is uncompromised by stability or cuttings transport issues.

Numerous tests of two different laboratory prototype drills, witnessed by industry experts at the Potter Drilling facility, have proven that hydrothermal spallation can be effective in a wide range of rock types from the surface to deep borehole conditions. Penetration rates approaching 30 ft/hr ROP, five to ten times higher than is achievable using conventional rotary contact bit technology, have been demonstrated. Potter Drilling is proposing to construct a complete prototype drilling system and to conduct field trials to determine the technology’s real world performance specifications.

State California
Objectives Potter Drilling will build a field-ready prototype drilling system using hydrothermal spallation, a revolutionary drilling method. This technology will overcome the cost and performance barriers of current conventional drilling methods in deep, hard rock applications. By establishing rates of penetration (ROP) many times higher than is possible with competing technology and eliminating bit wear and drill string fatigue, hydrothermal spallation drilling can transform the costs of geothermal well construction and enable widespread deployment of Enhanced Geothermal Systems (EGS).
Awardees (Company / Institution) Potter Drilling, Inc.
Awardee Website
Partner 1 Professor Jefferson Tester, Cornell University

Funding Opportunity Announcement DE-FOA-0000075
DOE Funding Level (total award amount) $4,999,999.57
Awardee Cost Share $2,479,243.00
Total Project Cost $7,479,242.57

Principal Investigator(s) Dr. Jared M. Potter, Potter Drilling, Inc.

Targets / Milestones The outcome of this portion of the project is expected to provide critical input to future development of full-scale hydrothermal spallation drilling systems, thereby serving as a bridge between basic research and commercial technology deployment.

Location of Project Raymond, CA

Impacts Five to ten times higher rates of penetration, approaching 30 ft/hour in hard rock is estimated if successful.
Funding Source American Recovery and Reinvestment Act of 2009
References EERE Geothermal Technologies Programs[1]


  1. EERE Geothermal Technologies Programs