Utilizing Historic Borehole Acoustic Data for Sub-Seismic Imaging and Advanced Reservoir Properties

Abstract Existing historic full waveform borehole acoustic data can be utilized to obtain formation information previously overlooked or unavailable, due to new processing methods or updated reservoir management requirements, without the need for new data acquisition. While seismic data is often reprocessed due to new developments in processing algorithms, full waveform borehole acoustic data from array acoustic tools are often overlooked as a source of additional reservoir information. Full waveform monopole and dipole waveforms contain a wealth of information beyond the basic compressional and shear slowness results typically provided. Slowness resolution enhancement, stoneley permeability profile calculation, azimuthal anisotropy, transverse anisotropy, and deep shear wave imaging are all viable additional processing outputs from existing datasets. Multiple additional results can be extracted from existing data, without drilling a new well, or in order to optimize drilling or logging programs for new wells. Resolution enhancement of compressional and shear slowness may be used to better delineate thin bedded environments. Stoneley Permeability provides a continuous permeability profile to compliment known mobility points from formation testing, or to provide a baseline to assess the long term production performance. Anisotropy processing gives valuable input into the geomechanical setting, and can enhance seismic processing by fine tuning the velocity field into three dimensions. Deep Shear Wave Imaging can be performed on existing cross-dipole datasets to give sub-seismic imaging of acoustically reflective surfaces such as bed boundaries or faults more than 50ft away from the wellbore, increasing the reach of the acoustic logs far from the wellbore. Reprocessing of historically recorded full waveform borehole acoustic data is a cost effective way to obtain additional formation information to enhance reservoir models or plan future field developments.