The Underexplored Shelf-Edge Plays of the West Africa Transform Margin: A Play Opening Case Study on Merged 3-D Seismic and Well Datasets Through Togo, Benin, and Western Nigeria

Abstract

Introduction Mesozoic and Tertiary paleo-shelf edges have long been identified by Africa oil explorers as offering the opportunity for shallow marine reservoir facies, combined with structural trapping styles and sealing transgressive muds. In addition to this shelf-edge play, pro-platform talus slope and mass-flow fan deposits, shed off the platform top or front and deposited to onlap the shelf edge, provide a secondary exploration target, typically within the same license area. Through the Transform Margin of Togo, Benin and NW Nigeria these plays are present but noticeably under-explored. In Nigeria, Mesozoic age mixed clastic and carbonate shelf-edge plays host the Aje and Ogo Fields, whilst in offshore Benin, the shelf edge play that lies distally to the Seme fields was the target for the Gbenonkpo-1 exploration well drilled in 2014. In the waters of western Benin and Togo, multiple leads in stacked Mesozoic and Tertiary shelf-edge plays are imaged but to date are untested by drilling. Recent merged 3D and 2D seismic datasets over Togo, Benin and Nigeria now provide for the first time a continuous image of the shelf-edge and pro-platform plays across 3 countries and some 10 blocks, supported by well data. The opportunity thus presents itself for oil companies to interpret, explore and de-risk this multi-country play and high-grade available acreage and farm-in opportunities. A new shelf-edge play opener in the WATM? Recent prospectivity and play fairway work across these three countries has identified considerable prospectivity within four shelfal sequences; Albian-Cenomanian, Turonian, Santonian-Campanian and Maastrichtian and a number of exciting leads have been identified, mapped and risked. The application of a sequence stratigraphic framework has helped to predict facies distribution and sequence constrained facies maps show where the best shelf-edge reservoir qualities and pro-platform fan deposits may be. Basin modelling work indicates that charge is low risk whilst rock physics work has constrained litho-fluid facies and has modelled elastic properties to further de-risk the identified leads. Conclusions There is significant overlooked shelf-edge and pro-platform prospectivity through Togo, Benin and Nigeria. The presentation will show examples the shelf edge and pro-platform play concept and a number of leads and prospects associated with these plays, located in both open acreage and farm-in opportunities, will be presented and explained.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018