Permeability Recovery and Enhancements in the Soda Lake Geothermal Field, Fallon, Nevada

Abstract

During the 1980s the apparently low permeability 77-29 and 84-33wells at the Soda Lake field were improved into useful long-term production or injection wells with standard perforation recompletions of cemented casings. In the early 1990s long term low pressure injection into well 81-33 either created or restored permeability that had not been recognized or had been damaged during drilling operations. Because of this historic response to stimulation, a technique that employs deflagration (the targeted ignition of a propellant to force a pressure wave into the surrounding formation) has been performed on 3 Soda Lake wells. In 2009 and 2010 relatively small charges had uncertain success in wells 45A-33 and 41B-33 due to the fact that other well modifications occurred at the same time. Charges 2.3 times larger became available in 2011 and three of these were used in the 25A-33 well. Immediately following the deflagration of the propellant charges, 5 days of low pressure (<150 psi) injection improved the injectivity by 20 fold from 30 gpm to over 600 gpm. Magma ignited the larger charges in three perforated sections of the well at 4153', 4575' and 4911'. Within two weeks of the stimulations using deflagrating materials the injection capacity of the well steadily increased from an initial 30 gpm to a steady flow over 600 gpm, with a maximum of about 750 gpm, all of this occurring at normal injection system pressures less than 150 psig.