Adaptive Viscoelastic-Waveform Inversion Using the Local Wavelet Transform for Geothermal Reservoir Characterization at the Blue Mountain Geothermal Field

Abstract

Seismic attenuation is a key parameter for geothermal reservoir characterization. Viscoelastic-waveform inversion has potential to reconstruct both subsurface velocities and attenuation coefficients. However, the strong trade-offs between velocity and attenuation parameters make it difficult to invert for the attenuation parameters reliably. We develop a novel adaptive viscoelastic-waveform inversion method based on the local wavelet transform for velocity and attenuation inversion. We first use a multi-scale elastic-waveform inversion scheme to invert for the velocity models, and then employ a spectral amplitude-ratio misfit function based on the local wavelet transform of seismic traces for attenuation inversion. We verify the method using synthetic seismic data, and validate it using a field seismic dataset acquired at the Blue Mountain geothermal field. Our preliminary results demonstrate that the regions with high-attenuation coefficients may be associated with fluid-filled fracture/fault zones in geothermal reservoirs.