Structure, Evolution, and Petroleum Systems of the Tano Basin, Ghana
Published:January 01, 2014
Stuart Lake, Aram Derewetzky, Neil Frewin, 2014. "Structure, Evolution, and Petroleum Systems of the Tano Basin, Ghana", Sedimentary Basins: Origin, Depositional Histories, and Petroleum Systems, James Pindell, Brian Horn, Norman Rosen, Paul Weimer, Menno Dinkleman, Allen Lowrie, Richard Fillon, James Granath, Lorcan Kennan
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The West Africa Equatorial Margin has recently become a focus area for petroleum exploration, because of recent material success in the deep-water Cretaceous clastic play. The discovery of the Jubilee Field in 2007 has been the catalyst for more intense exploration scrutiny, and the Tano basin has yielded a number of new discoveries. The Tano basin, located on the equatorial margin off the south coast of Ghana, is a prolific petroleum province defined by the Romanche fracture zone to the southeast and the St. Paul fracture zone to the northwest. The break up on this portion of the south Atlantic, of which the Tano basin is a part, initiated during the Aptian. A series of rift basins developed, eventually connecting to the evolving South Atlantic Ocean. Each of the rift segments has a unique structural and depositional history characterized by the interaction of pull apart and lateral shear motions of rift and transform boundaries, respectively. Asymmetrical rifting dictates alternating narrow and wide margins and, as a consequence, has an enormous influence on the petroleum potential of the basins being created. Deposition of turbidites began during the early drift phase (Cenomanian-Turonian) and continues to this day. Early Cretaceous source rock deposition was strongly influenced by synrift tectonic activity while the postrift marine source rocks were primarily controlled by global oceanic anoxic events. The environments of deposition for these source rocks are evident in the molecular composition of discovered hydrocarbon fluids in the Tano basin and are testimony to the complexity and differentiation between each different basin along the margin. The quality of discovered fluids is further controlled by maturation, migration, and reservoir transformation.