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Taking the Utica to its Depositional Limits: Through Facies Changes and Across the Entire Appalachian, Illinois and Michigan Basins

Williams, Ralph A.; Leighton, Danielle L.

Approximately 13,000 digital wells logs penetrating the Utica were interpreted and correlated in order to visualize the Utica to its extinction or outcrop within the USA. A visualization or pictorial representation of the Utica Shale is presented which highlights relationalities between the Utica play and the depositional system of approximately 450 million years ago which was responsible for depositing it. These relationships will be displayed, understood, and transmitted through concise graphic visualizations across the Appalachian, Illinois and Michigan Basins.

One hundred thirty thousand wells were initially digitized across the 3 basins, of which it was determined that 13,000 wells or 10% of the wells penetrated the Trenton/Black River. The procedure to construct a digital stratigraphic framework of the Utica Play was as follows: (1) a detailed digital stratigraphic framework of the underlying Trenton/Black River was constructed to bring a reliable set of chronostratigraphic correlations up to the base of the Utica Shale; (2) the gamma ray shale baseline of the Queenston/Reedsville Shale was meticulously normalized to allow a reliable set of very detailed chronostratigraphic correlations above the Utica which would not have been possible with analog or raster well logs; (3) a detailed digital stratigraphic framework of the Utica/Point Pleasant was constructed based upon normalized gamma ray LAS and density LAS.

From this process, it was determined that 10 to 15 subdivisions of the Utica/Point Pleasant system should be individually mapped and analyzed to provide the fabric by which all types of geologic and engineering data can be subdivided by concise geologic time and to understand the facies changes which result in reservoir rock.

The results of the detailed correlation of the Utica and overlying and underlying formations are presented in both isopach maps and cross section views with hundreds of wells with lines of section connecting the three northeastern USA basins from St. Louis to New York and Tennessee to Canada. The cross sections also visualize the relationship of low density log measurements to organics.

The gross isopach of the Utica defines the extent of the area of northeastern USA where the Utica was deposited and will contain the entire Utica time slice including all facies (not limited to the shale facies).


AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013