Calibrating Theoritical Sandstone Reservoir Models with Realistic Bedding Structures on Outcrops; Applications in Thin Bedded Fans and Heterolithic Tidal Reservoir Sands, Examples from the Sedimentary Basins of Nigeria

Anyadike, Emeka. A.¹, Efosa. Arthur², Samuel. J.L Coker³ (1) University of Benin, N/A, Nigeria (2) University of Benin, Benin City, (3) University of Benin, Benin City, Nigeria

Reservoir properties which affect fluid flow and distribution such as porosity,permeability and mud/sand volumes are governed by small scale (mm-scale to cm-scale) geometries occurring below the conventional well log or seismic resolution.The effect of low resistivity pay zones or reservoir sand bodies caused by sand layers with varying grain-size distribution and /or sorting that create electrical anisotropy due to variations in water saturations,morphology and distribution of fluid phases has given some concern. Simulating, scours and channels, sand geometries and all aspects of crossbedding including parallel bedding, ripple marks, epsilon bedding, flaser and lenticular crossbedding,hummocky and swaley crossbedding, trough bedding, herringbone cross-stratification, massive bedding ,bioturbation , fractures and dip orientations of these structures from outcrops is invaluable in calibrating the Geophysical, Petrophysical and Geological (core) data and is quite useful in upscaling when integrating well to seismic data set. Outcrop studies of Cretaceous to Recent aged sediments across some sedimentary basins of Nigeria revealed a high diversity of associated sedimentary structures recognized as predepositional, syndepositional, and post depositional across the stratigraphic successions. These structures with their associated facies and facies associations, simulated processes which led to their formation, permeability and porosity estimations across them,geometries and their dip orientations were useful in making to make realistic models which will help address the problems caused by permeability anisotropy,low resistivity reservoir sand bodies thereby improving hydrocarbon reserve volume and to accelerate production profiles in frontier prospects.