Date of Graduation
Eberly College of Arts and Sciences
Geology and Geography
The Upper Devonian Bradford Group of west-central Pennsylvania is a commonly targeted natural gas reservoir. The Greater Punxsutawney area covers parts of Jefferson, Indiana, and Clearfield counties, and within this area the Bradford Group is composed of nine separate drillers' sandstones. These sandstones are interpreted in outcrop to have been deposited in a range of depositional environments from sandy turbidites of the prodelta to muddy shoreface and sand-ridge complexes of the delta front. This study referenced gamma ray and bulk density e-logs from 269 wells to generate a data base from which maps and cross sections were generated for these beds in the subsurface, and allow for the application of sequence stratigraphic principles.;In this study, the Bradford Group is interpreted to be composed of two fourth order sequences. These sequences are subdivided into individual systems tracts based upon both the sequence stratigraphic surfaces observed in cross section and trends seen in map view. Porosity maps within the study area show that reservoir quality is generally influenced by the proximity of the sandstones to shoreline and dependent on the volume of lithic fragments which controls both the volume of primary porosity that was preserved during compaction as well as the volume of secondary porosity that might have been created by the dissolution of these lithic grains.
Johnson, Anthony G., "Subsurface stratigraphy of the Upper Devonian Bradford Group in the Greater Punxsutawney area, Pennsylvania" (2008). Graduate Theses, Dissertations, and Problem Reports. 4386.