USING GEOPHYSICAL DATA TO EVALUATE THE POTENTIAL FOR CARBON SEQUESTRATION IN INDIANA, LANCASTER, AND LEBANON COUNTIES, PENNSYLVANIA

Previous studies (DCNR & MRCSP) have suggested that Pennsylvania may contain lithologic and structural features that are possible traps for carbon sequestration. The purpose of this study is to determine if gravity data, used in conjunction with other geophysical information, can be used to effectively model subsurface variations to determine the potential for carbon sequestration in Lebanon, Lancaster, and Indiana counties. While borehole and seismic data have been used to create a structure map in Indiana County, these data are limited to a portion of the county. However, extensive gravity data exists across the state of Pennsylvania. The existing structure maps, can be correlated with the gravity anomalies.

Work to date has shown that there is a strong spatial correlation between the long-wavelength negative gravity anomalies and the structural highs identified from the other geophysical data. This suggests that the structural highs may be cored by lower density sedimentary formations suitable for sequestration. Subsurface density models are being created that are constrained by both the gravity anomalies and the structure surfaces.

These models will be used to calculate specific storage potential and resulting carbon offsets. Indiana County is of interest due to the abundance of un-mineable coal beds and depleted oil and gas fields. Furthermore, specific formations (basal sandstones) within the county have been identified as suitable for sequestration. Lebanon and Lancaster Counties are of interest due to the presence of a deep and expansive saline formation.

Contour maps of the gravity data have been created utilizing ArcGIS. Polynomial fits were used to remove short-wavelength gravity variations caused by shallow lithologic variations and to remove longer-wavelength regional trends. The subsequent remaining negative long-wavelength anomalies may represent structures cored by low density sediments. Lithologic and structural data from both the surface and, where available, the subsurface will be used next to control models of structure and bed thickness. The models will then be used to make estimates on the potential volume available for sequestration. The potential will be summarized using subsurface structure maps, cross-sections and volume estimates for each region.