Determination of porosity and permeability out of dispersion analyses of borehole wall displacements

During reservoir stimulation by hydraulic fracturing, shear and elongation fractures are induced in the vicinity of the borehole. The radiated seismic energy results not only in a direct propagation of waves to a seismic receiver positioned in the borehole, but also to a displacement in the borehole along the borehole axis. The same displacement can be achieved by the application of controlled sources. A detailed knowledge of the wave forms created will make it possible to distinguish the waves carried in the borehole from the seismic waves running in the rock. In addition a method is obtained that allows to determine the porosity and permeability of the rock.