Directly imaging steeply-dipping fault zones in geothermal fields with multicomponent seismic data

Abstract

For characterizing geothermal systems, it is important to have clear images of steeply-dipping fault zones because they may confine the boundaries of geothermal reservoirs and influence hydrothermal flow. Elastic reverse-time migration (ERTM) is the most promising tool for subsurface imaging with multicomponent seismic data. However, conventional ERTM usually generates significant artifacts caused by the cross correlation of undesired wavefields and the polarity reversal of shear waves. In addition, it is difficult for conventional ERTM to directly image steeply-dipping fault zones. We develop a new ERTM imaging method in this paper to reduce these artifacts and directly image steeply-dipping fault zones. In our new ERTM method, forward-propagated source wavefields and backwardpropagated receiver wavefields are decomposed into compressional (P) and shear (S) components. Each component of these wavefields is separated into left-and right-going, or downgoing and upgoing waves. The cross correlation imaging

Ambient Noise Surface Wave Reverse Time Migration for Fault Imaging

“…Faults are basic components of subsurface structures that represent discontinuities in physical properties. In addition to being the controlling factor of major tectonic earthquakes (e.g., Angelier, 1990; Martin et al., 2016; Sibson, 1983), subsurface faults also play an essential role in natural resources, including hydrocarbon accumulation and formation of oil and gas reservoirs (Aydin, 2000), aggregation of metallic ore deposits (e.g., Goldfarb et al., 2005; Spencer & Welty, 1986), and generation of geothermal reservoirs (Chen & Huang, 2015). Therefore, detailed characterization of subsurface faults is crucial for understanding tectonic activities and for exploring natural resources.…”

Characterizing shallow fault zones by integrating profile, borehole and array measurements of seismic data and distributed acoustic sensing

“…Tomographic imaging of steep, shallow fault zones is an essential part of geothermal studies (Chen & Huang, 2015). Permeable fault zones are suitable as reservoir targets as they are pathways for high‐temperature fluid flows (e.g., Corbel et al., 2012; Chen & Huang, 2015; Goyal & Kassoy, 1980). Earthquakes can also occur at fault zones when the stress field changes during exploration or production of a geothermal field.…”