USGS Science⌕ Search

Geology topics

Research about Ohio, Pennsylvania

Source-linked reports with geographic coverage including Ohio, Pennsylvania.

4 recordsLinked to original sources
USGS2014

Composition of natural gas and crude oil produced from 14 wells in the Lower Silurian "Clinton" Sandstone and Medina Group Sandstones, northeastern Ohio and northwestern Pennsylvania

The geochemical processes that control the distribution of hydrocarbons in the regional accumulation of natural gas and crude oil in reservoirs of Early Silurian age in the central Appalachian basin are not well understood. Gas and oil samples from 14 wells along a down-dip transect through the accumulation in northeastern Ohio and northwestern Pennsylvania were analyzed for molecular and stable isotopic compositions to look for evidence of hydrocarbon source, thermal maturation, migration, and alteration parameters. The correlation of carbon and hydrogen stable isotopic composition of methane with thermal maturation indicates that the deepest gases are more thermally mature than independent estimates of thermal maturity of the reservoir horizon based on the conodont alteration index. This correlation indicates that the natural gas charge in the deepest parts of the regional accumulation sampled in this study originated in deeper parts of the Appalachian basin and migrated into place. Other processes, including mixing and late-stage alteration of hydrocarbons, may also impact the observed compositions of natural gases and crude oils.

Ohio, Pennsylvania↗
USGS2001

Subsurface correlations and sequence stratigraphic interpretations of lower Silurian strata in the Appalachian Basin of northeast Ohio, southwest New York, and northwest Pennsylvania

Significant quantities of recoverable natural gas resources are estimated to be in the regionally extensive Lower Silurian Medina Group and “Clinton” sandstone of the Appalachian Basin (Gautier and others, 1995; Ryder and others, 1996; Ryder, 1998). In order to assess these accumulations of natural gas more accurately, the U.S. Geological Survey (USGS) has investigated the Silurian stratigraphy along six lines of cross section located in New York, Pennsylvania, Ohio, and West Virginia (fig. 1). Cross section A–A' extends about 375 mi from northeast to southwest and is oriented approximately parallel to the nearby paleoshoreline of the Silurian epeiric sea. The remaining cross sections extend about 100–200 mi from northwest to southeast and are oriented nearly perpendicular to the paleoshoreline. Stratigraphic investigations along A–A' were reported by Ryder (2000), correlations along D–D' were reported by Keighin (1998), and investigations along E–E' and F–F' were in progress at the time of this publication. This report provides correlations for Silurian strata along cross sections B–B' and C–C', which are located in the northern part of the Appalachian Basin (figs. 1 and 2). Cross section B–B' extends about 140 mi from Chautauqua County, N.Y., to Clinton County, Pa., and C–C' extends about 200 mi from Lake County, Ohio, to Clinton County, Pa. Correlations are made along B–B' and C–C' for the Lower Silurian Medina and Clinton Groups, Lower Silurian Tuscarora and Rose Hill Formations, and Lower and Upper Silurian Lockport Group and Mifflintown Formation (lower part). Emphasis is placed on the Medina Group because it is the principal natural gas reservoir in the Silurian deposit.

Ohio, Pennsylvania↗