--> ABSTRACT: Shallow Seismic Reflection Confirmation of Berea Gas Pool Structure and Faulting, Portage County, Ohio, by Alexandros Sergoulopoulos, Alan H. Coogan, and Donald F. Palmer; #91041 (2010)

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Shallow Seismic Reflection Confirmation of Berea Gas Pool Structure and Faulting, Portage County, Ohio

Alexandros Sergoulopoulos, Alan H. Coogan, Donald F. Palmer

The Mississippian Berea Sandstone is a reservoir for shallow gas in Suffield Township, Portage County, Ohio, in the informally named St. Joseph's Church field. Production of natural gas from the Berea reservoir is from sandstone up to 60 ft (18 m) thick with porosity in the 15-25% range. The field, which is at about 400 ft (720 ft above sea level), lies updip from the Akron-Suffield fault zone and more or less along strike from the Berea gas field in Randolph Township to the southeast. The trap for the gas is anticlinal and the overlying Sunbury Shale (so-called "Coffee shale") is the seal. Initial field pressures were about 80-100 psi (552 kPa).

A shallow seismic survey of 6 refraction and 26 CDP reflection lines was made, using a six-channel Bison recording unit. Reflections were obtained from depths down to 800 ft through well-documented formations of known lithology, including glacial till (kame and non-kame), Sharon shale, Sharon Sandstone, Sunbury Shale, Berea Sandstone, Bedford Shale, and Ohio Shale. Correlation of the seismic data with logs from three separate wells drilled with cable tools was used to derive interval velocities for depth control.

Seismic reflections from the top of the Berea Sandstone were consistent over the area with depths from wells. Unexpectedly high elevations of the Berea Sandstone on the southern crest of the anticlinal dome lay in a straight line trending east-west. This suggests the presence of a fault with a general east-west strike and vertical displacement of 15-18 ft.

Marginal gas production was encountered just north of the plotted fault on a line between the best producing wells on 450-500 ft centers. Better gas-producing wells lie on the downthrown side of the small east-west fault and close to the fault. The fault is probably one of many in the area and may be a splinter fault of the Akron-Suffield fault zone.

AAPG Search and Discovery Article #91041©1987 AAPG Eastern Section Meeting, Columbus, Ohio, October 7-10, 1987.