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Inferring Geothermal Reservoir Processes at the Raft River Geothermal Field, Idaho, USA, Through Modeling InSAR ‐Measured Surface Deformation
Author(s) -
Liu Fang,
Fu Pengcheng,
Mellors Robert J.,
Plummer Mitchell A.,
Ali Syed Tabrez,
Reinisch Elena C.,
Liu Qi,
Feigl Kurt L.
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2017jb015223
Subject(s) - geology , geothermal gradient , interferometric synthetic aperture radar , poromechanics , deformation (meteorology) , groundwater related subsidence , pore water pressure , petrology , fault (geology) , geotechnical engineering , subsidence , seismology , geomorphology , synthetic aperture radar , geophysics , remote sensing , oceanography , porous medium , structural basin , porosity
Ground surface deformations detected with interferometric synthetic aperture radar provide valuable information for inferring subsurface reservoir processes that are difficult to observe directly. This study aims at building a reservoir model that honors the available geological, hydrological, and geomechanical data and also produces ground surface deformation consistent with interferometric synthetic aperture radar measurements at the Raft River Geothermal Field. In the thermo‐hydro‐mechanical coupled model developed, the reservoir deforms as a result of the rock's poroelastic response to changes in hydrologic pressure and thermal expansion/contraction. The results indicate that the observed deformation is the result of pressure decrease in the deep production reservoir and pressure increase in a shallower reservoir that accommodates the injected fluid (likely in the Salt Lake Formation). The combination of the uplift around injection wells with subsidence around the production wells, affected by the Bridge Fault as a flow barrier, creates a complex pattern of surface deformation in which the center of subtle subsidence significantly deviates from the location of the production wells. A parametric study suggests that (a) the Bridge Fault Zone is likely a flow barrier, (b) the surface deformation appears to be insensitive to the presence of the Narrows Structure, and (c) additional flow barriers likely exist to shape the flow system. This case study demonstrates the utility of a high‐fidelity forward model that honors available known information and thermo‐hydro‐mechanical coupled processes in understanding geothermal reservoir characteristics.