The application of hydraulic and thermal stimulation techniques to create enhanced geothermal systems

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Title The application of hydraulic and thermal stimulation techniques to create enhanced geothermal systems
Publication Type dissertation
School or College College of Engineering
Department Chemical Engineering
Author Bradford, Jacob Thornley
Date 2016
Description Geothermal energy production requires temperature at depth, a working fluid to transport heat to the surface, and a network of fluid pathways connecting injection and production wells. These requirements constrain the availability of geothermal energy resources. Enhanced Geothermal System (EGS) development expands geothermal resource availability by artificially generating networks of fluid pathways in the reservoir. This is accomplished through hydraulic and thermal stimulation of the geothermal reservoir. Hydraulic and thermal techniques were applied at the Raft River geothermal field as part of a Department of Energy (DOE) EGS development project. The test well RRG-9 ST1 was hydraulically stimulated three times between February 2012 and April 2014. Since June, 2013 continuous injection of sub-reservoir temperature plant water has been used to thermally stimulate the well. The stimulation program has resulted in a large increase in the injectivity of the well, an increase from less than 20 gpm in June 2013 to nearly 1,000 gpm in April 2016. Wellbore imaging and temperature analysis identified a northeast striking fracture zone intersecting the well between 5,640 and 5,660 ft. measured depth (MD) that has nominally accepted all of the injected fluid. Microseismic activity, related to the stimulation program and plant activity, was used to track possible fluid pathways within the reservoir. The microseismic data indicate that the injected fluid moves primarily to the northeast through the Narrows Zone, a northeast striking fault structure that bisects the field. Tracers injected into RRG-9 ST1 and recovered at the production wells RRG-2 and RRG-4, located to the northeast of RRG-9 ST1, support this theory. It is hypothesized that water injected into RRG-9 ST1 moves through the intersecting fracture zone which connects into the Narrows Zone, and then moves along the Narrows Zone to the northeast. This conceptual model was numerical simulated using FALCON, a finite element reservoir simulation code developed by Idaho National Laboratory. The modeling suggests that both thermal and hydraulic fracturing mechanisms played an important role in improving the injectivity at RRG-9 ST1. The stimulation program at Raft River has successfully demonstrated the effectiveness of hydraulic and thermal stimulation techniques. RRG-9 ST1 is now in commercial use.
Type Text
Publisher University of Utah
Subject Enhanced Geothermal Systems; Hydraulic Stimulation; Raft River; Thermal Stimulation; Chemical engineering
Dissertation Name Doctor of Philosophy
Language eng
Rights Management (c) Jacob Thornley Bradford
Format application/pdf
Format Medium application/pdf
ARK ark:/87278/s6x10c8c
Setname ir_etd
ID 1345223
Reference URL https://collections.lib.utah.edu/ark:/87278/s6x10c8c
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