Patent ID: 8553493

Claim:
A method for estimating formation permeability using at least one attribute of Stoneley waveforms in a borehole under logging while drilling conditions of a drill string with a drill collar at a distal end, said method comprising: determining process parameters including a desired frequency band to increase signal-to-noise ratio, wherein the frequency band depends on formation type and drilling noise; determining model input parameters for a waveform model including properties of rock formation and the borehole, including a borehole fluid and the drill collar; modeling a Stoneley waveform based on the input parameters including the drill collar radius, the drill collar material density, the drill collar material shear velocity and the drill collar material compressional velocity, and a range of discrete values for permeability; processing the modeled waveforms corresponding to the selected input values of permeability to obtain Stoneley wave slowness or Stoneley wave attenuation; generating a model curve of the Stoneley wave slowness or Stoneley wave attenuation as a function of permeability by using the values of permeability; transmitting a sonic wave and receiving a sonic Stoneley wave with a LWD tool including the drill collar; processing the received waveform for Stoneley wave slowness or Stoneley wave attenuation using the same processing method and processing parameters used to process the modeled waveforms; and using the model curve that relates permeability to the Stoneley wave slowness or Stoneley wave attenuation, estimating formation permeability from the attribute of the Stoneley wave measured during LWD operations.