Seismoelectric signals produced by mesoscopic heterogeneities: Spectroscopic analysis of fractured media

MARINA ROSAS-CARBAJAL; DAMIEN JOUGNOT; RUBINO J. GERMÁN; LEONARDO MONACHESI; NIKLAS LINDE; HOLLIGER KLAUS

Seismoelectric Exploration

Wiley

Año: 2018;

In fluid-saturated porous rocks, the presence of mesoscopic heterogeneities such as, forexample, fractures, can produce measurable seismoelectric signals. The conversion of mechan-ical energy into electromagnetic energy is related to wave-induced fluid flow (WIFF) betweenthe heterogeneities and the embedding background. This physical mechanism is a well-knowncause of seismic attenuation, which exhibits a strong frequency dependence related to rock phys-ical and structural properties. Consequently, seismoelectric signals arising from WIFF are alsoexpected to depend on various material properties, such as the background permeability andfracture characteristics. We present analytical and numerical approaches to study the effectsof mesoscopic heterogeneities on seismoelectric signals. We develop an energy-based approach to quantify the total energy converted to seismoelectric signals at the sample scale. In partic-ular, we apply our theoretical framework to fractured rock sample models and study the spec-tral signature of the resulting seismoelectric signals. This study highlights the influence of themechanical and hydraulic properties, as well as the geometrical characteristics, such as degreeof fracture connectivity, of the probed medium on the resulting seismoelectric signal.