High Resolution Seismic Inversion for Characterization of Reservoir Lateral Heterogeneity
Recent developments in spectral decomposition and sparse layer seismic inversion methodologies have greatly improved both the resolution and the accuracy of seismic attributes, inverted impedances, elastic moduli, and inferred rock properties. These, in turn, lead to improved thin bed resolution and reservoir characterization for both conventional and unconventional reservoirs. Combining pre-stack seismic elastic inversion, seismic attribute analysis, and geostatistical constraints, leads to the direct calculation of rock property reservoir volumes that tie well control and realistically capture lateral variations. These are computed in a format that can be directly input into flow and geomechanical models. These same methods can be used to help land laterals and improve frac programs. What is perhaps surprising is that improved resolution has been accompanied by more realistic indications of lateral changes in rock properties. Conventional seismic attributes and sparse-spike inversion results frequently show lateral discontinuities when the geological layering is, in fact, continuous. Apparently paradoxical, the improved temporal seismic resolution from sparse-layer inversion is accompanied by more spatially stable inversion results; these reflect the true underlying geological continuity, while simultaneously better revealing actual discontinuities caused by faults, channel boundaries, etc. These improvements in seismic determinations are simply the consequence of better collapsing of the seismic wavelet by the sparse-layer inversion process due to a better parameterized earth model. These concepts are illustrated with numerous examples from a wide variety of reservoir types, with an emphasis on unconventional reservoirs.
AAPG Datapages/Search and Discovery Article #90214 © 2015 Southwest Section AAPG Annual Convention, Wichita Falls, Texas, April 11-14, 2015