Ichnofacies and Reservoir Properties of Shoreline Deposit in the Coastal Swamp Depobelt of the Niger Delta
Ogechi C. Egbu, Gordian C. Obi, Celestine O. Okogbue, and A. W. Mode
Department of Geology, University of Nigeria, Nsukka, Nsukka, Nigeria
Core samples from 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 fossils assemblages across the shoreline sediments were evaluated and integrated with known porosity and permeability values derived from core plugs to asses 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 important relationship between biogenic sedimentary structures and reservoir quality.
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