Single-well imaging using full-waveform sonic data

Louis Chabot

I am proposing a processing and imaging flow to image acoustic impedance contrasts away from the borehole wall using full-waveform data acquired with a conventional acoustic well-logging tool in an open-hole environment. The proposed flow adapts known surface-seismic processing steps and optimizes them for the borehole environment. Improvements over past flows include the use of radial filtering for linearno ise attenuation and equivalent-offset prestack time migration for imaging. 2D finitedifference and raytracing methods were used to create and test the flow on synthetic data. The flow was next applied to a full-waveform sonic dataset, recorded over a section of the 8-8-23-23W4 well, Blackfoot, Alberta, intersecting three coal seams obliquely. Although the three targeted coal seams were not very well imaged, the final composite sonic image showed promising indications of dipping interfaces elsewhere. The principal cause for this fair result was the large angle between the borehole axis and the dipping beds.