Full-array waveform data processing of dipole sonic logging data can provide stable shear slowness logs; however, resolution is limited to array size. To better resolve smaller features, such as thin beds or formations with strong heterogeneity, multishot subarray waveform processing is performed. The method sorts recorded waveforms over multiple firings into subarrays that are aligned across their central depth midpoints. Each subarray is processed for coherence as a function of slowness and frequency. Then, all of the individual frequency semblance subarray maps are averaged to increase the signal-to-noise ratio (SNR) to resolve stable dispersion curves of the primary flexural mode. An adaptive weighting function is used to emphasize the dispersion curve portions that are reliable with good SNR and little dispersion effect. Processing of field data from a fast well demonstrates the effectiveness of this method at resolving shear slowness across thin beds.
Presentation Date: Monday, October 15, 2018
Start Time: 1:50:00 PM
Location: 212A (Anaheim Convention Center)
Presentation Type: Oral