S. George Pemberton¹, T. Saunders¹, Andrew Pulham², Murray K. Gingras³, Floyd Henk¹

(1) University of Alberta, Edmonton, AB
(2) University of Colorado, Boulder, CO
(3) University of New Brunswick, Fredricton, NB

ABSTRACT: Using Trace Fossils in Reservoir Characterization: Ichnogenera and Ichnofacies and their influence on Permeability Fabrics and Reservoir Performance

The application of trace fossil analyzes in reservoir studies has advanced enormously over the past decade. Gone are the days when degree of bioturbation was the only recorded facet of Ichnology. Outcrop and subsurface investigations by the authors have shown that a detailed understanding of the specific trace fossil genera and species, their diversity and morphology and their relationship with other physical and biological fabrics can lead to a much improved, and often a dramatic, re-evaluation of reservoir architecture and distribution of permeability/porosity trends.

At a bed scale, it was assumed that ichnofossils had an adverse effect on permeability and porosity trends. Recent work, however, indicates that certain ichnofabrics can enhance the vertical and lateral transmissibility of important reservoir boundaries. These are often surfaces that may have sequence stratigraphic significance, but can be higher order surfaces typically not recognized by more traditional reservoir description techniques. At a reservoir zonation scale, ichnofacies and specific ichnogenera can provide important clues about the genesis of important architectural elements within reservoirs and their spatial relationships. The improved understanding of these elements, their scale and inter-connectivity, is critical to successful reservoir management strategies.

We will present case studies from siliciclastic and carbonate reservoirs in which ichnofacies analyzes have resulted in improved reservoir understanding. In the past, it was thought that ichnofossil studies were soley for exploration projects but they are proving to be even more important in exploitation. This can be manifested and measurable in net present values or in improved reserve calculations.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado