3D seismic attribute-assisted stratigraphic framework and depositional setting characterization of frontier Miocene to Pliocene aged Agbada Formation reservoirs, deep offshore Niger Delta Basin

Abstract

In the Freeman Field, located about 120 km (75 miles) offshore southwestern Niger Delta at about 1300 m (4260 ft) water depth, 3D seismic attributes-based analyses and stratigraphic based geometric models enhance and constrain the characterization of the stratigraphic framework and depositional setting of Miocene-Pliocene Agbada Formation reservoirs in the deep offshore Niger Delta Basin for improved oil and gas exploration and exploitation. An integrated approach was employed involving 3D seismic interpretation, prospectivity mapping, subsurface modelling, as well as spectral decomposition and amplitude attributes analyses. Attribute-assisted seismic interpretation and mapping results reveal a massive northwest-southeast trending shale-cored detachment anticline containing numerous associated normal faults. Strata in the Freeman Field are interpreted to have been deformed by extension in the crestal region of a compressional fault-related fold and secondarily by inflation of the anticline by flow of the ductile, undercompacted, and overpressured Akata Shale. The Mid-Miocene to Pliocene Agbada Formation reservoirs occur as part of a channelized fan system, mostly deposited as turbidites in an unconfined distributary environment on a massive northwest-southeast trending shale-cored detachment anticline containing numerous associated normal faults, except a reservoir sand that occurs as channel fill in a confined depositional environment within a submarine canyon that came across and eroded a previously deposited distributary fan complex, suggesting likely presence of prospective areas for hydrocarbon exploration southwest of the Freeman Field.