BRANNOCK, MICHAEL C., Quaker State Corporation, Belpre, OH

ABSTRACT: The Starr Fault System of Southeastern Ohio

The Starr fault system is a series of east-west-trending faults located in southeastern Ohio. This fault system was discovered by mapping the anomalous sedimentary sequence of the "Big Lime." The Big Lime is a driller's term for the stratigraphic section that includes the Lower Devonian Onondaga through Middle Silurian Lockport formations. The use of trend-surface analysis identified the probable fault orientation, which was then verified by seismic.

The system is a series of high-angle faults, originating in the Precambrian, that occur along a narrow corridor traversing several townships. Analysis of the sedimentary section preserved by faulting indicates fault movement after the deposition of the Bass Islands Formation, which was followed by a regional unconformity that removed the Bass Islands and a part of the upper Salina Formation. The Onondaga subsequently was deposited, masking fault movement evidence in the shallower formations. Some minor movement occurred later, as is evidenced by expansion in the Devonian shale sequence. The geometry of the fault system and other data suggest a pattern similar to the Albio-Scipio field of southern Michigan.

A group of wells were drilled to test the Ordovician Trenton and Black River formations to determine the existence of secondary dolomite, which could be a potential reservoir. Secondary dolomite was encountered, but no commercial hydrocarbons were found in either the Trenton or Black River. Other formations produced hydrocarbons and water from fractured zones that were not known for this behavior. Other probable fault systems in southern Ohio, identified by using the same mapping techniques, may provide deeper targets for future drilling.

AAPG Search and Discovery Article #90995©1993 AAPG Eastern Section Meeting, Williamsburg, Virginia, September 19-21, 1993.