Integrated Deposystem Analysis of Lower Pottsville Strata (Lower Pennsylvanian) in the Greasy Ridge Oilfield, Central Appalachian Basin, Southern Ohio, U.S.A.

Ronald L. Martino
Marshall University, Huntington, WV

The Greasy Ridge field is an anomalous area of shallow (550-800 ft) oil production. It was discovered by accident in 1985 during development of a Clinton gas field. It has produced over 600,000 bbls through primary and secondary methods which represent about 20 % of the original in place oil. Production occurs from cross-stratified to ripple-bedded, fine- to very fine-grained sandstones that range up to 30 ft thick, with porosities as high as 20 %. Initial production after hydro-fracturing averages about 5 bbls/day; and the highest IP reported is 15 bbls/day. Though these figures may not be considered to be that impressive, the low cost of drilling and completing such shallow wells provides for an attractive, cost-effective play.

Wireline logs from 63 wells in the roughly 1 square mile field are combined with data from 5 cores drilled nearby to provide high resolution facies identification and correlations. Additional insight is provided by outcrop analogs in lower Pottsville and equivalent Breathitt strata as close as 25 miles away. These outcrops contain cycles that reflect fluvial incision followed by aggradation of braided fluvial-to-estuarine sands, which are capped by coals and restricted marine shales. Recent advances in estuarine depositional models help facilitate a better understanding of stratigraphic traps in the Pottsville Formation.

The development of a comprehensive depositional model for the Greasy Ridge Field will facilitate further development and secondary recovery, and should be helpful in the discovery of similar Pottsville plays that may have been overlooked elsewhere in southern Ohio and vicinity.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005