Patent ID: 6807487
Filing Date: 2004-10-19
Classification: G01V,Y10S

Abstract:
A new method for determining the in-situ Slow-wave or Drag-wave velocity, both these waves representing the same phenomenon, of permeable reservoir rock formations which are continuous between two wellbores, and from that determination, using the existing known mathematical relationship to calculate the bulk tortuosity of the interconnected pores of reservoir rock, and estimating the bulk permeability of a reservoir formation between seismic transmitters and seismic receivers, the method comprising:Transmit a mono-frequency signal generated by a seismic transmitter or seismic transmitters in a wellbore and received by a seismic receiver or seismic receivers in another or the same wellbore, spectrally analyzing said received signals, determining the presence of the Drag Wave by determining the presence of the frequency side lobes of the Primary seismic wave, of a selected discrete frequency, the frequency side lobes in the said spectrum of the received signals being created by the nonlinear elastic interaction of the Primary mono-frequency seismic wave with the Drag Wave, the Drag Wave being generated through solid/liquid coupling as the Primary Compressional Wave propagates through a permeable reservoir formation between two wells, and the said formation has fluid-filled interconnected pores.