Hydrothermal Spallation for the Treatment of Hydrothermal and EGS Wells: a Cost-Effective Method for Substantially Increasing Reservoir Production Flow Rates

Abstract

There is a need in many geothermal projects to greatly increase the productivity and/or injectivity of wells, with a direct impact on project economics. Flow testing in wells and associated modelling of EGS reservoirs has suggested that low productivity from EGS reservoirs can result from near-wellbore impedance, a restriction of fluid flow within the immediate vicinity of the borehole walls. Further modelling suggested that altering the geometry of an existing wellbore by longitudinally slotting the borehole wall could significantly decrease near-wellbore impedance. Hydrothermal spallation is an ideal technology to create slots in the hard rock found in these reservoirs. This paper describes the results of tests of hydrothermal spallation well enhancement technology in the laboratory and initial field trials as well as its application to increase production from geothermal wells.