Natural Gas from Oriskany Formation in Central New York and Northern Pennsylvania

Abstract

The recent discovery of two large gas fields producing from the Oriskany formation has been responsible for much leasing and drilling activity in central New York and northern Pennsylvania. The geologic section consists of an almost complete series of Devonian rocks, which, because of the general southwest dip, are all exposed from the outlets of Seneca and Cayuga lakes to the Pennsylvania state line. The Devonian section of this region is plentifully supplied with black bituminous shales, but the lack of suitable reservoir rocks has probably been the cause of the comparatively restricted area in which gas is produced from these rocks. The Oriskany sandstone, which is the producing horizon of both the Tyrone and Farmington fields, is a very erratic formation because of ex raordinary conditions of deposition. It is the basal Devonian formation throughout the greater part of central New York, but it overlaps progressively older formations westward from the Hudson Valley. The folds of the area, in general, parallel the great mountain folds of central Pennsylvania, but the structures of central New York are regarded as en echelon folds which are due to a change in the direction of strike of the main system of folding. Most of the structures are believed to be the surface expression of underthrust faults. Closures occur along the anticlines where the direction of strike locally changes and where the Appalachian folds intersect the axes of what is believed to be an Ordovician system of folding. Other gas fields may be expected from the Oriskany, but the success of exploratory drilling will depend not only on the location of favorable structures, but also on the occurrence of the sandstone.