Stratigraphic Analysis of Natural Gas Bearing Strata, Steuben County, New York

Natural gas production in western New York has an almost 200 year history. Due to recent surges in prices, there has been renewed interest in the region. The Onondaga limestone and the Marcellus shale are targets of interest in Steuben County. In particular, paleo-reefs within the Onondaga formation have been found to have sufficient porosity and permeability to be large gas producers. Initial studies of the local stratigraphy using geophysical logs shows two types of structures commonly associated with natural gas. Paleo-reefs show thicknesses in the Onondaga increasing from approximately 3 to 8 meters along reef margins to in excess of 35 meters within the reef. In the same locations, deposition of the Marcellus shale results in beds that thin from approximately 4 to 6 meters thick along the paleo-reef highs to less than 3 meters, occasionally absent, over the reefs. Another common gas-bearing environment appears to be tectonic controlled. Some thickening is seen in the Onondaga formation, bordered by offsets in the Onondaga-Marcellus contact. In these situations, the overlying Marcellus shale does not thin over the thicker portions of the Onondaga. Ongoing analyses are evaluating boring logs and limited core data to connect the detailed information analyzed near paleo-reef structures to develop a model for the region.