--> ABSTRACT: From Rodinia to Pangaea: Unconventional Petroleum Systems in the Appalachian Basin and Their Global Sequence Stratigraphic and Geodynamic Context, by Messer, Ailsa C.; Reynald, Mark A.; #90142 (2012)

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From Rodinia to Pangaea: Unconventional Petroleum Systems in the Appalachian Basin and Their Global Sequence Stratigraphic and Geodynamic Context

Messer, Ailsa C.*1; Reynald, Mark A.1
(1) Neftex Petroleum Consultants Ltd, Abingdon, United Kingdom.

Palaeozoic black shales were deposited on the eastern margin of the United States of America (New York to Alabama) from the Cambrian rifting of Rodinia until the amalgamation of Pangaea in the Carboniferous. Many of these black shales including, the Cambrian-aged Conasauga, Ordovician-aged Utica, Silurian-aged Rochester and Devonian-Mississippian aged Esopus, Marcellus, Dunkirk and Sunbury shales, are potential or economic shale gas/oil plays.

Published estimates of unconventional hydrocarbon resources are typically many times greater than proven conventional reserves, yet exploration campaigns for unconventional resources have met with variable levels of success since their widespread application began in 2003, with well production rates varying across the area of a play. A key control on success is regional geology, in particular the geographic and stratigraphic distribution of organic matter, silica, and carbonate. The distribution of these key elements has been qualitatively modelled using our sequence stratigraphic and palinspastic plate models.

The Appalachian Basin sedimentary record shows a cyclical stratigraphic organisation which, when compared with our global 3rd-order sequence stratigraphic Earth Model, suggests a prominent control on sedimentation by eustatic sea level change. The highstand systems tract (HST) to early transgressive systems tract (TST) is typically characterised by organically-lean fracable sediments, which are overlain by TST to maximum flooding surface (MFS) organic-rich black shale horizons. Drivers behind these organic-rich black shale pulses, while enhanced by local conditions, are often global in nature and include for example, oceanic circulation patterns and anoxic events. These processes are best illustrated using palinspastic Gross Depositional Environment maps.

Using our sequence stratigraphic and palinspastic plate models the unconventional shale gas/oil plays of the Appalachian Basin are put into a local, regional and global context. By understanding the key features that define the effectiveness of the well-explored Appalachian Basin, predictions can be made about sweetspots in other more frontier potential shale gas/oil basins.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California