UTILIZING PSEUDO-3D SEISMIC DATA TO EXAMINE INTERNAL HETEROGENEITY OF STACKED RESERVOIRS FOR FUTURE CO2 STORAGE AT PROJECT ECO2S, KEMPER COUNTY, MS

The Geological Survey of Alabama (GSA) is completing interpretation of a pseudo-3D seismic survey acquired in July 2021 for Phase 3 of the project “Establishing an Early CO₂ Storage Complex in Kemper County, Mississippi: Project ECO₂S.” An earlier phase of the project utilized a limited series of pre-existing 2D seismic lines in order to investigate risks associated with cross-cutting faults from deep below the proposed injection intervals. While no seismic-scale faults were observed above the Paleozoic unconformity, the established lower boundary of the stacked reservoirs of interest, the quality of the data did not allow for examination of potential internal heterogeneity of the reservoirs. Thus, Phase 3 aims for a more detailed interpretation of the internal stratigraphy of the three targeted stacked reservoirs utilizing optimally processed multi-2D and pseudo-3D data. The seismic survey is a multi-2D survey and is referred to as pseudo-3D because all channels were alive during all shots. This allowed the creation of pseudo-3D data from a relatively high fold set of interstices where 3D seismic can be interpolated.

These newly acquired seismic lines create an opportunity for in-depth modeling of CO₂ injection and plume migration that was not possible with the previous seismic surveys. The Lower Cretaceous Paluxy Formation and Washita-Fredericksburg interval contain a series of stacked sand bodies interbedded with shales. The saline reservoirs are overlain by thick shales acting as regional seals. Within the Upper Cretaceous interval, the Tuscaloosa Group contains the Lower Tuscaloosa Massive Sand member reservoir with the overlying Tuscaloosa Marine Shale as a regional seal. An additional major regional confining unit, the 900-foot-thick Selma chalk, overlies each of the potential target reservoirs. The lateral continuity and internal stratigraphy of the individual sands within these formations is a focus of this study.

A future benefit of this pseudo-3D survey will be the potential for 4D studies of the CO₂ plume post-injection, as the acquisition parameters can be replicated.