The Use of Advanced Percussion Drilling to Improve Subsurface Permeability for Enhanced Geothermal Systems

GeoMechanics Technologies proposes to investigate the use of advanced percussion fracturing technology to stimulate and enhance permeability in hot rock for EGS development without large volume water usage-We will perform this Phase I investigation by executing the following work plan: (1) Building and expanding on our own and others’ past theoretical work to develop analytical descriptions of stress wave propagation induced by dynamic shear and compression loading at the bottom of a borehole- Develop and describe dynamic fracturing processes induced by shear, compression and tensile waves; (2) Develop and document numerical simulation of the percussion fracturing process, including dynamic stress wave propagation, fracture creation and fracture extension- Apply numerical modeling to consider alternative wellbore shear and compression loading scenarios and fracture extent for alternative rock properties; (3) Fabricate a laboratory system to test and demonstrate percussion fracturing in core samples- The system would include control and monitoring of axial stress and radial stress- It would also include a controlled percussion drilling motor and impact rod system; (4) Apply the laboratory apparatus to investigate percussion fracturing on rock samples under a variety of differential stress conditions; and (5) Comparing laboratory observations with numerical model results, providing confidence and validation to subsequently use numerical simulation modeling at the field scale-