Crosshole Seismoelectric Measurements in Borehole Models With Fractures

Abstract

A seismic wave propagating in a fluid-saturated porous media, moves ions in the double layer between the fluid and solid and induces an electric field. When there is discontinuity (such as a fracture), the seismic wave induces a radiating electromagnetic (EM) wave. In this paper, we investigate seismoelectric fields in media with vertical and inclined fractures using cross-borehole measurements in the laboratory. Our laboratory results show that an acoustic source in a borehole generates a radiating EM wave at a vertical fracture, which is recorded by an electrode in the second borehole. The position of the fracture can be determined by the arrival times of the EM wave and acoustic wave, and the velocity of formation. The position of an inclined fracture between two boreholes can be determined by placing the acoustic source at a different depth and recording with real or synthetic arrays of acoustic receivers in the second borehole.