Measurements and Theory

A Stoneley wave propagating in a borehole generates a flow of pore fluid in permeable zones intersected by the borehole. In turn, this flow of pore fluid induces a streaming electrical field. This thesis is an experimental and theoretical investigation of the electrical fields induced by Stoneley waves. The main emphasis of this thesis is to understand the electroseismic phenomena that are observed in the field. In the first experiment described in this thesis, we measured Stoneley-wave-indu-ced electrical fields in a borehole drilled through fractured igneous rocks. Analysis of field data confirms that the electrical fields that we measured were induced by fluid flow in fractures. The normalized amplitude of these electrical fields correlated with the fracture density log. In the second experiment, we measured Stoneley-wave-induced electrical fields in several boreholes in vuggy dolomite. In dolomite, the normalized amplitude of the Stoneley-wave-induced electrical field correlates with the porosity of the forma-tion around the borehole. Further, the Stoneley-wave-induced electrical fields hav