Application of ichnology in the paleoenvironmental reconstruction and reservoir characterization of the Avalon and Ben Nevis formations, Hibernia field, Jeanne d'Arc basin, Grand Banks of Newfoundland

Ichnology, the study of fossilized tracks, trails and burrows, greatly refines sedimentological and stratigraphic analysis within hydrocarbon-bearing strata. Because trace fossils represent the behavioral response of organisms to their physical and chemical surroundings, they provide unique insight toward the characterization of paleoenvironmental settings. Additionally, in highly bioturbated reservoirs, trace fossils represent heterogeneities that drastically alter production properties such as effective permeability, fluid flow paths, and petroleum saturation in comparison with non-bioturbated media.; The mid-Cretaceous Avalon/Ben Nevis interval comprises a variety of marginal marine and marine settings, making it a good candidate for illustrating the strength of high-resolution, integrated lithofacies and ichnofacies analysis. Trace fossil assemblages characteristic of brackish versus open marine depositional settings are easily recognized. As such, a paleoenvironmental framework within the Hibernia area is attainable, despite limited core and wireline log coverage. A range of sedimentary environments including arid coastal plain/marsh, barrier-island or micro- to mesotidal estuary, delta and offshore have been delineated. Ichnology also aides in the identification of an unconformity and a transgressive surface of erosion within this interval.; Although two sandstone bodies constitute the main producing units, substantial petroleum reserves are found within bioturbated muddy sandstones of the Ben Nevis Formation. Biogenic textural heterogeneity, manifested as mud-filled, mud-lined or meniscate-filled burrows within a sandy framework, is a major concern for enhanced recovery strategies. Probe permeameter analysis confirms that permeability is significantly lower in muddy burrows (herein interpreted as Pelosichnus mumorpha n. ichnogen., n. ichnosp.) than in the hosting sediment. Flow is therefore focused in the more permeable sandy framework with the burrows acting as baffles to flow, creating dispersivity and non-uniform saturation. New modeling software utilizing a modified invasion-percolation technique (MPath) can incorporate burrow morphology, connectivity, density, and burrow-framework permeability contrast to accurately predict fluid trajectories through bioturbated media. Using this method, flow properties at the burrow scale can ultimately be incorporated at the reservoir production scale.; This study represents the first sedimentological/stratigraphic analysis of the Avalon and Ben Nevis formations approached from an ichnological perspective. As a result of this integrated methodology, understanding of the facies architecture and reservoir properties of this interval is greatly improved.