In the Central Appalachian Basin, southwest Pennsylvania, recently collected high-quality 3D seismic data provide critical information vital to the delineation of basin structures and depositional facies. It is therefore important for the development and verification of ideas associated with structural architecture and growth history of the basin. Traditional wiggle trace imagery has a low dominant frequency and signal-to-noise ratio. The conventional seismic attributes extracted from this data set, such as amplitude, frequency, and phase, are not effective at defining structural details and relations between faults and folds. To overcome these limitations, we have applied waveform regression, jointly with variance, and ant tracking to increase the resolution of structural features, leading to enhanced observations and interpretations. Forethrust to backthrust patterns and small-scale, intrainterval shear zones or detachment faults were observed within the Devonian intervals in which the Marcellus Shale has been developed. From the trend of discontinuities, the primary stress orientation during the Devonian was defined at approximately 105°–120° azimuth, which may affect drilling orientations in the hydraulic fracturing process of the Marcellus gas shale reservoir. Initial observations of gas production data hint at a correlation between structural quiescence and increased productivity in this study area. This effort demonstrates the importance of innovative 3D seismic-attribute techniques and analysis to understanding the relationship of subsurface structural features that are fundamental to the success of future exploration for and production of oil and gas.
Regional Mapping and Reservoir Analysis of the Middle Devonian Marcellus Shale in the Appalachian Basin