Electroseismic and seismoelectric responses at irregular interfaces: Possible application to reservoir exploration

Seismoelectric and electroseismic interface responses resulting from the electrokinetic effect are useful to study the properties of subsurface medium. In this article, we investigate the characteristics of these interfacial signals generated at irregular subsurface interfaces considering hydrocarbon exploration scenarios. Adopting several typical models, the electroseismic and seismoelectric wavefields are calculated using the finite-difference frequency domain method. Besides the well-known electroseismic and seismoelectric signals created at a flat interface, the scattered seismic wave and scattered electromagnetic (EM) wave can also be generated by EM and seismic sources at subsurface scattering points, respectively. When an electric source is applied for excitation, the waveforms recorded by horizontally- or vertically-aligned receiver array indicate that electroseismic interface responses nearly do not change with the source locations and can directly delineate the shapes and morphologies of the corresponding interfaces. Simulations of seismoelectric wavefield show that both the interface seismoelectric responses and scattered EM waves display as flat events in the electric record. It is not easy to distinguish them if we do not know the realistic underground structure. Based on simulations, the electroseismic interface responses seem more promising than the seismoelectric interface responses for imaging the subsurface interfaces.