Shale Gas and Muddy Shelves: Comparing the Neogene-Quaternary Eridanos System (NW Europe) with the Devonian Catskill Delta (USA)
Moscariello, Andrea; Ventra, Dario; Zijp, Mart; ten Veen, Johan
The recent worldwide focus on gas- and oil-shales contrasts with our limited knowledge on the processes and geological context of environments dominated by fine clastic sedimentation. Development of such resources requires refined models that relate biogenic gas generation and storage to facies and architectural elements at depositional system scale, and to systems tracts and geotectonic setting at basin scale. A comparative research approach can relate paleoenvironmental conditions and allogenic forcing of well-studied depositional systems with those of shale prospects still under exploration.
We discuss sedimentological and architectural analogies and differences between the Neogene-Quaternary ‘Eridanos Delta' of northern Europe, which drained the Fennoscandian and Baltic shields westward through the present-day Baltic Sea, and the Devonian ‘Catskill Delta', which prograded into the Appalachian Foreland Basin (eastern USA) during the Acadian orogenic phase. In spite of their common denomination as ‘deltas', these clastic wedges actually consisted of fluvial to coastal environments linked to shallow-marine, mud-dominated shelves in a proximal-to-distal continuum. The Eridanos system hosts numerous productive shallow-gas plays in the southern North Sea offshore, whereas the Catskill system comprises important black-shale formations (Marcellus, Rhinestreet, Dunkirk, etc.) that charge the Appalachian hydrocarbon system.
Changes in base level and sediment supply, partly influenced by climate during the Plio-Pleistocene onset of glaciation, controlled the complex proximal architecture of the Eridanos Delta and are reflected by compositional and architectural changes in its mud-prone, basinal portion. The Eridanos Delta provides an example of well-constrained relationships between different forcing factors, sedimentary properties and the hydrocarbon potential of its shaly domain. These insights may support new predictive genetic models for black shales of the Catskill and other systems, especially if applied to high-order heterogeneities within and between shale bodies which were probably driven by allogenic factors at time scales of millions of years and shorter. The potential for future hydrocarbon production from such plays, especially in areas with surface footprint constraints (e.g. Europe), depends on the ability to unravel their internal variability, and thus to target intelligently the most productive stratigraphic intervals.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013