Searching High and Low: Correlating Shallow (Drift Phase) and Deep (Rift Phase) Structural Trends with Surface and Subsurface Geochemistry in the Niger Delta, West Africa
Published:December 01, 2015
William Dickson, Craig Schiefelbein, 2015. "Searching High and Low: Correlating Shallow (Drift Phase) and Deep (Rift Phase) Structural Trends with Surface and Subsurface Geochemistry in the Niger Delta, West Africa", Petroleum Systems in “Rift” Basins, Paul J. Post, James Coleman, Jr., Norman C. Rosen, David E. Brown, Tina Roberts-Ashby, Peter Kahn, Mark Rowan
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We began with three views of the same region of the Niger Delta: as seen by the geochemist in the nearsurface data; as seen by the prospect mapper in published subsurface seismic detail and well control; and by the regional structural interpreter in a crustal view from potential field data. We combine these shallow, intermediate, and deep views to illuminate the hydrocarbon plumbing system. Specific basement features, including the deep basin framework, were correlated to detailed published interpretations within the objective sedimentary section. We then showed hydrocarbon access to these features via evidence of leakage to surface with piston cores and correlated these results with oils geochemistries.
We built on an earlier tectonic-structural and geochemical interpretation (Dickson and Schiefelbein, 2011) of a transform/passive margin without the complications of salt-related deformation. Gravity data provided primary control for tectonic-structural interpretation, augmented by magnetics, depth, thickness, and published literature to define the deep rift-phase structure. Active hydrocarbon exploration meant that broad coverages of detailed 3D seismic and surface geochemical exploration programs have been acquired and presented in a half-dozen recent cited papers. From a non-exclusive study used here by permission, characteristic oil geochemistry of the Niger Delta was matched to the surface geochemical exploration results. This published and non-exclusive material facilitated the correlation between basement features and shallower drift-phase intrasedimentary structuring with inferred hydrocarbon leakage pathways terminating at the surface.