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Title: Anisotropic Elastic-Waveform Modeling for Fracture Characterization in EGS Reservoirs

Enhanced geothermal systems (EGS) contain newly created fractures in addition to possible existing fractures. Accurate characterization and monitoring of EGS reservoirs are crucial for optimal placement of new wells and effective extraction of geothermal heat. The fractured reservoirs behave as anisotropic media where seismic waves propagate with different velocities along different directions. In addition, the anisotropic properties of fluid-filled fracture zones could be different from those of dry fracture zones. We develop an optimized rotated staggered-grid elastic-wave finite-difference method for simulating seismic-wave propagation in heterogeneous, anisotropic media. Our new method uses a few extra grid points and optimized finite-difference coefficients based on the space-time dispersion relation, and reduce numerical dispersion of the conventional rotated staggered-grid finite-difference scheme. We validate our new method using synthetic vertical-seismic-profiling (VSP) data for an anisotropic geophysical model built with geologic features found at the Raft River EGS reservoir. This improved and optimized rotated staggered-grid finite-difference method provides an essential tool for analyzing VSP data, reverse-time migration, and elastic-waveform inversion in anisotropic, fractured reservoirs.
 [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
LA-UR--15-20435; SGP-TR--204
DOE Contract Number:
Resource Type:
Technical Report
Resource Relation:
Conference: 14. Workshop on Geothermal Reservoir Engineering, Stanford, CA (United States), 26-28 Jan 2015
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Geothermal Technologies Office (EE-4G)
Country of Publication:
United States
58 GEOSCIENCES anisotropy; elastic; fracture characterization; optimized finite-difference method; staggered-grid; rotated coordinates