Ichnofacies and Reservoir Properties of Shoreline Deposit in the Coastal Swamp Depobelt of the Niger Delta* O.C. Egbu 1 , G.C. Obi 2 , C.O. Okogbue 1 , and A.W. Mode 1 Search and Discovery Article #40412 (2009) Posted May 6, 2009 *Adapted from poster presentation at AAPG International Conference and Exhibition, Cape Town, South Africa, October 26-29, 2008 1 Department of Geology, University of Nigeria, Nsukka, Enugu State, Nigeria (mailto:sedogechy@yahoo.com) 2 Department of Geology, Anambra State University of Science and Technology, Uli, Anambra State, Nigeria Abstract Core samples from a shoreline deposit, which is one of the reservoirs of the Coastal Swamp Depobelt of the Niger Delta, were studied to assess the effect of burrowing on the reservoir quality. The abundance and diversity of trace fossil assemblages across the shoreline sediments were evaluated and integrated with known porosity and permeability values derived from core plugs to assess the effect of burrowing on permeability and porosity of the reservoirs. Results show that strongly burrowed reservoir intervals posses higher porosity and permeability values when compared with sparsely burrowed intervals. Whereas burrowed sediments of middle shoreface have permeability values between 177md and 967md, and porosity values within the range of 24% to 28.7%, sparsely burrowed middle sandstone units display permeability and porosity readings that range between 5.63md and 137md and 12.8% to 25.6% respectively. Similarly, burrowed sandstone units of the lower shoreface possess permeability values of 20md to 70md and porosity values of 20% to 23.7% while the sparsely burrowed lower shoreface sandstone units have permeability and porosity readings that range between 8.13md and 25.40md and 19.4 to 23.8% respectively. These findings suggest an important relationship between biogenic sedimentary structures and reservoir quality. Introduction Ichnology, the study of the ‘tracks, trails and burrows’ made by animals in various substrates, has grown tremendously in the last five decades as researchers have continued to expand its importance in sedimentologic studies. The utility of trace fossils is not limited to the interpretation of paleoenvironments, paleobathymetry, and paleoecological stress. Recent works have shown that ichnology can be applied to allostratigraphy (Pemberton et. al., 1992a) and sequence stratigraphy for delineation of key stratal surfaces (Bockelie, 1991;