Friday 8 February 2019

GeoPartners, in partnership with the Petroleum Directorate of Sierra Leone, announced a new 2D seismic survey offshore Sierra Leone to support the 4th Offshore Petroleum Licensing Round planned for later this year. The survey will comprise of over 9000km of new data and cover the full extent of the offshore area available in the Licence Round. Acquisition is planned to commence after completion of the necessary regulatory approvals and a subset of the data will be available for companies participating in the Licence Round.

Jim Gulland, Director, GeoPartners, said: “We are proud to have been awarded this contract by the Petroleum Directorate to support their ongoing exploration efforts and specifically the forthcoming Licence Round. The new survey is the first to cover the entire offshore area from shallow to ultra- deep water, providing ties to all existing wells and allowing a complete evaluation of the available acreage. Sierra Leone has proven oil discoveries and this new long offset survey will highlight the potential of this underexplored area”.

Geological Summary

The continental margin of Sierra Leone developed during Cretaceous extension and early opening of the equatorial Atlantic. The shallow water shelf and deep-water basins define distinct hydrocarbon provinces, bisected by the Sierra Leone Transform Zone (SLTZ); a major strike-slip system associated with complex structures including rotated fault blocks and local inversion.

Four out of five exploration wells drilled in the southern deep-water basin encountered light oil (34-42° API), condensate or gas in the Upper Cretaceous section. Reservoirs include stacked, high net / gross channelised turbidite sands, with good porosity, located in slope apron fan systems of the Cenomanian and Turonian. Interbedded marine shales are organic-rich, oil-prone and mature. Equivalent source / reservoir facies are prospective on the French Guiana conjugate margin (with the Zaedyus-1 well proving 72 m net of oil pay in high quality Cenomanian and Turonian fan sands). Untested, large slope apron and basin floor fan plays are recognised on the Sierra Leone margin with potential mature sands sourced from the South American and West African margins.

Thick sequences of Apto-Albian and Cenomanian fluvio-deltaic to marginal marine sandstones, proven by wells on the southern shelf, are interbedded with oil-prone lacustrine shales. This play could prove prospective on the broad, unexplored shelf north of the SLTZ.