--> Abstract: The Marcellus of New York through Time, by J. E. Leonard, C. P. James, V. Leighton, H. C. Samuel, and G. G. Lash; #90090 (2009).

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The Marcellus of New York through Time

Leonard, Jay E.1; James, Charles P.1; Leighton, Van 1; Samuel, Heidi C.1; Lash, Gary G.2
1 Platte River Assoc., Inc., Boulder, CO.
2 Department of Geosciences, SUNY - College at Fredonia, Fredonia, NY.

The renewed interest in the Middle Devonian Marcellus Shale formation has stimulated interest in the evaluation of shales not just as source rocks, but now as productive plays. A better understanding, and more thorough application of the thermal and burial history to calculation of the rock and kerogen properties is more vital than ever to the high grading of current and future holdings. An integration of the complex depositional and structural history with the timing and behavior of methane adsorption in kerogens can provide a tool to delineate areas of enhanced retained and adsorbed gas preservation. In the Northern Appalachian basin the Marcellus kerogen undergoes transformation into hydrocarbons from as early as Late Devonian to Early Jurassic.

The methane adsorption potential is at minimums in the Mid-Carboniferous and at the end of the Triassic. As the temperature and pressure vary across the state the effect of the fracturing or reactivation of existing faults can be very significant on a local basis. The temperature maximum coincides with initiation of the breakup of Pangea. There are periods of excess pressure beginning in the Early Carboniferous and extending into the Permo-Triassic.

The critical predictive elements are the interplay between saturation, gas adsorption and fracturing. As the methane adsorption potential changes with temperature and pressure over time, the fracture timing can cause greater loss of gas reserves; if the methane adsorption potential is at a minimum during periods of increased stress. These periods of stress occur in the Late Pennsylvanian and Early Permian with periodic uplift and fault movement through the Cenozoic: typified by events like local volcanism, the Chesapeake Bay impact, the Adirondack uplift and the Pleistocene glaciation.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009