SEISMIC ATTRIBUTE ASSISTED CHARACTERIZATION OF THE PENNSYLVANIAN UNCONFORMITY

The Pennsylvanian aged unconformity, which is a detrital surface, separates the beds of Permian age strata from the Lower Paleozoic in the Central Basin Platform. Seismic data interpretation indicates that the Pennsylvanian unconformity is an angular unconformity, with multiple normal faults beneath it, as well as a thrust fault which add to the complexity of the region. The goal of this study is to characterize these complex faults, unconformity, and any other geologic features that may influence hydrocarbon production and CO₂ sequestration.

The Pennsylvanian aged angular unconformity creates pinch-outs between the beds above and below of the unconformity. We computed the spectral decomposition and reflector convergence attributes and analyzed them to characterize the angular unconformity and faults. The spectral decomposition attribute divides the broadband seismic data into different spectral bands to resolve thin beds and show thickness variations. On the other hand, the reflector convergence attribute highlights the location and direction of the pinch-outs as they dip south at angles between 2˚ - 6˚. After reviewing findings from RGB blending the spectrally decomposed frequencies along the Pennsylvanian unconformity, we observed channel-like features and multiple linear bands in addition to the faults and pinch-outs. We suspect that the identified linear bands could be the result of different lithologies associated with the tilting of the beds and, in turn influence hydrocarbon accumulation. Further research is needed to confirm this hypothesis and further characterize the channel-like features.

This project highlights the essence of 3D seismic attributes in delineating geologic structures.