Many factors can influence the productivity of shale resource plays. In the Allegheny National Forest area, in Pennsylvania, the development of the Marcellus shale has increased rapidly due to the vast quantities of natural gas within this formation. Although, the reasoning behind the spatial variation of good producing wells is under heavy investigation, it is yet unclear. We believe that basin architecture is critical for the understanding of the Marcellus shale production.
NEOS GeoSolutions undertook a multi-measurement, geological and geophysical study in the Allegheny National Forest area. This comprehensive interpretation involved the integration of newly acquired airborne gravity, magnetic, magneto-telluric, electromagnetic, radiometric, and hyperspectral datasets, with seismic and well data and public domain datasets. The airborne gravity and magnetic data provided an understanding of the basin architecture and structural framework from the basement to the surface. These data were integrated with well and seismic data in 2-D profiles to provide a more detailed understanding of the basin stratigraphy and structure. A 3-D inversion model was created based on the 2-D profiles. These results, combined with the magneto-telluric and electromagnetic data provided insight of the basement depth and lithological variation, and its relationship to the sedimentary basin and the production of the Marcellus shale. A high susceptibility region found at the basement level, suggesting lateral lithological variations within the basement unit, show correlation with Marcellus shale production. It is likely that areas of localized granitic intrusions agree with higher thermal gradient, higher hydrocarbon maturity, better hydrocarbon migration and areas of enhanced production. Additionally, the integration of hyperspectral and radiometric data revealed a correlation between surface hydrocarbon seeps and the presence of radioactive elements. Ultimately, we evaluated the unconventional resource potential carrying out a static uncertainty analysis of the Marcellus shale and provide quantitative risk maps. The analysis indicated that the Marcellus interval in the area contains significant natural gas resources with some liquids, with an average of 20 BCF/mi2, and as much as 40 BCF/mi2 when including adsorbed gas.
This multi-measurement interpretation approach can be used in any basin and unconventional resource around the world, and cannot only help provide insights of specifics to the basin and its natural resources, but it can also be done in an environmentally friendly way and in areas were seismic data may not provide all the answers needed.