Patent ID: 11960043
Assignee: SCHLUMBERGER TECHNOLOGY CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. A method, comprising:
obtaining a waveform from a sonic borehole device in a formation;
processing the obtained waveform from the sonic borehole device to obtain at least one value of a Stoneley, flexural, quadrupole and Pseudo-Rayleigh dispersion;
performing a computation to produce a theoretical dispersion of the Stoneley, flexural, quadrupole and Pseudo-Rayleigh dispersions for the waveform;
performing an initial estimate of mud slowness using both the processing of the obtained waveform and the theoretical dispersion;
calculating a first mismatch between the processed waveform obtaining the at least one Stoneley, flexural, quadrupole and Pseudo-Rayleigh dispersions and the theoretical dispersions of the Stoneley, flexural, quadrupole and Pseudo-Rayleigh dispersions;
estimating at least one DTmud value as a vertical depth profile;
calculating a second mismatch between the theoretical dispersion and the processed waveform using the at least one estimated DTmud value;
estimating at least one Thomson parameter for the formation by minimizing the second mismatch;
using regression, calculating at least one revised Thomson parameter over multiple depths;
calculating a third mismatch between the theoretical and measured dispersions based upon the updated values for Thomson parameter based upon the regression; and
estimating a final value of the at least one Thomson parameter by minimizing a mismatch between the theoretical and measured dispersions.