High-fidelity slowness values
BestDT automated sonic waveform processing for best slowness addresses the problems inherent in the semblance technique. Parameter selection is based on job information, tool configuration, and the external environment.
Integrated semblance processing manages dispersive and nondispersive waveforms. The improved multishot technique enhances the vertical resolution.
Labeling is replaced with a statistical tracking technique that generates consistently good-quality results. The easy-to-understand error bars are part of quality control. The finalization process selects the best curve automatically to output for each wave component analyzed.
For cased hole applications and very slow formations, BestDT processing has specific techniques and parameters that produce optimum results.
Automated parameter selection
The sonic logging tool configuration and well environment determine the waveform output characteristics and the selection of processing parameters. Factors that influence selection include the tool type, borehole size, mud slowness, and formation type. There are procedures for special circumstances, such as logging through casing or where the formation compressional slowness is less than that of the borehole fluid.
Zoning
For large intervals, BestDT processing uses a preliminary estimate of the compressional delta-t log. This detects major changes in log conditions separating macrozones where processing parameters can be kept constant. Zoning also indicates the bed boundaries to use as a guide for tracking slowness results.
Slowness determination
The integrated slowness determination process includes the semblance computation with dispersive and multishot processing. This allows uniform processing of all waveform types and allows adjustment of the vertical resolution.
Benefits
- Improved reliability and accuracy of results
- Quick turnaround from data acquisition to interpretation
- Standardized answers with minimum user intervention
- Better evaluation of layered reservoirs
- Improved computation of compressional and shear slowness behind casing
- Compressional slowness in very slow formations
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