Fluid Diversion in an Open-Hole Slotted Liner

Abstract

Achieving multiple zone stimulation in an open-hole section in an EGS well could potentially reduce the cost of EGS power production by 40% or more by increasing flow capacity and production on a per well basis. A first field operational step was taken towards proving this concept in an injection well in a geothermal field. The goal of this operation was to test the use of diverters in temporarily sealing off fractures in a geothermal reservoir and optimizing the injection profile of the given well. Success of this operation could be built upon to improve production of EGS and conventional geothermal reservoirs.
The test well had fluid exiting the wellbore behind both the blank and slotted portions of an un-cemented liner. Heat recovery for reservoir recharge could be improved by forcing injection deeper in the well. Therefore, the goal of the operation was to temporarily seal off the shallow fractures and direct injection deeper in the well. Achieving this goal was made more difficult by the presence of the slotted liner.
Positive indications were measured after pumping a diverter into the well. Both pressure increase and cooling of the wellbore below the deepest injection point were measured using a conventional PTS logging tool after diverter material was introduced into the injection stream. Results of this operation and subsequent injectivity tests will be presented along with analysis of the data showing the effectiveness of the diverter treatment. The operation was extremely successful at isolating the zones both above and below the top of the slots in the liner.