THE RELATIONSHIP OF STATE-WIDE SOIL GAS SURVEYS TO FRACTURE DATA AND LINEAMENTS: DELINEATION OF SUBSURFACE STRUCTURES RELATED TO HYDROCARBONS

Since 1991, the UB Rock Fracture Group has conducted soil gas, fracture mapping and lineament analysis research throughout New York State. Data from over 18,000 soil gas analyses integrated with structure data and lineaments have resulted in the successful delineation of subsurface structure. Open fractures can provide preferential pathways for the migration of thermogenic gases, primarily methane and ethane, to the surface. The work is based upon this concept that thermogenic gas will seep upward on fractures, resulting in higher abundances in overlying soil. By correlating fracture mapping and lineaments with the soil gas anomalies, a detailed subsurface structural map can be compiled and evaluated. The results from the following studies have demonstrated the effectiveness and applicability of soil gas analyses in locating and characterizing faults and fractures related to oil and gas prospects as well as to environmental concerns across New York State. 1). Bass Island structural trend in Western New York. The resulting data delineated seven cross-strike discontinuities in and around an underground natural gas storage facility. 2). Cuylerville (Akzo-Nobel Mine). Soil gas anomalies successfully outlined the collapse of a portion of the mine and predicted areas of potential subsidence. 3). Faults that affect the Ordovician Trenton-Black River section. Narrow zones in which anomalously high methane and ethane concentrations (ethane indicates the gas is thermogenic, not biogenic) were found along strike with zones of intense fracturing (FIDs) around Seneca and Cayuga lakes. 4). Clarendon-Linden Fault System in the Finger Lakes region. Soil gas surveys also traced the CLF farther South into Allegany County. 5). Bath region (Bath Petroleum Storage Inc). Soil gas investigation provided evidence that surface rocks at the B.P.S.I. facility have not been affected by an ENE-trending fault and that the facility is not leaking stored gases (propane and butane). 6). Devonian fractured shale reservoirs in Chenango County. The research in this region shows positive results in characterizing fractured shale reservoirs and shows areas with the greatest potential for future exploration.