Numerical investigation on seismoelectric wave fields in porous media: porosity and permeability

Compared with the seismic wave fields, the influence of porosity and permeability to seismoelectric coupling may be more significant. The seismoelectric effect mainly forms the coseismic signals (CS) and interface response (IR). The influences of the porosity and permeability on the two types of seismoelectric field are still not clear. In this paper, we numerically analyze the response characteristics of the CS and IR with the dependency of porosity and permeability, respectively. The differences in the sensitivity of the CS and the IR fields to porosity and permeability are also determined. The results show that the change of permeability is mainly sensed by the IR field, while the CS has almost no obvious response to it: both the CS and IR fields are sensitive to the change of porosity, but the sensitivity of the IR field is higher and with the increase of porosity, the discrepancy between the sensitivity of the CS and IR fields to porosity changes increases. The signal amplitude anomaly will be caused in both P-wave fields and seismoelectric fields (IR and CS) at the geological body where the porosity changes, but the change of permeability has little impact on the P-wave and only induces an obvious IR amplitude anomaly in seismoelectric fields. This indicates that the seismoelectric effect can better reveal the connectivity characteristics of the geological body than the seismic wave. This investigation can help to distinguish the sensitivity of seismoelectric response to porosity and permeability more clearly.