FAULTS AND HYDROCARBON RESOURCES IN THE APPALACHIAN BASIN OF NEW YORK STATE

This paper examines the relationships among hydrocarbon reservoirs and faults active during Rome Trough time, Trenton/Black River (TBR) time, Silurian and Devonian times, and Alleghanian times. The UB Rock Fracture Group integrated Landsat (Earthsat, 1998) and topographic lineaments, detailed structural and sedimentological/stratigraphical analyses at over 2500 outcrops, well log data, soil gas data, and seismic reflection data in order to identify and trace both surface and subsurface faults across the Appalachian Basin of New York State (NYS). We previously found common structural themes across the Appalachian Basin in NYS, including sets of reactivated fault systems with 3 differing orientations, as well as Alleghanian thrust flats and ramps. Additionally, we have now recognized the extent of reactivated Rome Trough-related faults. Fault influence on oil and gas plays includes: 1) fault controlled deposition of reservoir quality rocks, 2) fluid migration along fault systems resulting in vuggy porosity from dissolution and later precipitation, and 3) fracture porosity reservoirs related to fault systems. In contrast, some faults systems without good seals at high structural levels allowed shallow reservoirs to drain (such as the Clarendon-Linden Fault System which has no Medina production)

In central NYS (Finger Lakes region), the Trenton/Black River gas fields are found along reactivated faults. Shallow-level gas is a potential in the Alleghanian E-striking thrust/fold systems in the same area. In western NYS (Cattaraugus, Allegany, Chautauqua, and Erie counties), fault block motion interplay with sea level resulted in localized nearshore sands such as the Rushford, a correlative of the Bradford sands. Similarly, fault block motion controlled the pinchout of the Silurian salt, which in turn controlled the location of thrust ramps such as the Bass Island Trend, recognized as the most prolific fracture play in NYS. Deeper reservoirs occur along the ENE-trending Rome trough-related faults, along N-striking reactivated faults that follow Grenvillian trends, and along CSDs. In eastern NYS (Chenango and Otsego counties), Silurian reservoir-quality nearshore sand deposition was partly controlled by reactivated Grenvillian and TBR faults. Higher level fault-bend folds also have potential.