Seismoelectrical Method - Data Acquisition, Processing, and Interpretation

Data Acquisition, Processing, and Interpretation

Measurements are recorded using the instrument and system setup described above. Data processing consists of stacking repetitive hammer (or explosive) shots and removal of power line and other noise as described above. This processing is conducted on the computer-receiver while in the field. Depending upon field conditions, up to 20 soundings can be conducted in a day. It is expected that measurement time will increase proportionally with stacking times, and that long stacking times would be needed in the vicinity of power lines.

The signal files are processed to give a sounding plot of permeability and porosity against one-way seismic travel time. Values for a simple seismic velocity model are required to allow time-to-depth conversion. The resulting logs against depth are displayed in the field.

Output from the electroseismic inversion is typically a plot showing hydraulic conductivity versus depth. This interpretation assumes a one-dimensional layered earth. In theory, the inversion also can derive fluid conductivity and fluid viscosity from the rise time of the signal. Where many soundings are measured in close vicinity, a pseudo 2-D cross-section can be generated.

The maximum depth of penetration of electroseismic measurements is stated to be about 500 m depending upon ambient noise and water content. Lateral resolution is not stated in the literature but is expected to be on the order of the depth of exploration. No information was found regarding the vertical resolution of the method.