Seismic Stratigraphic Interpretation of a Prolific Deep Water Reservoir Using High Quality 3D in the Rovuma Delta, Mozambique
David M. Jones
Senior Geophysical Advisor, Anadarko Petroleum
The Golfinho-Atum discovery is located in the central portion of the Rovuma Basin near the Mozambique-Tanzania border. It is entirely contained within the Area 1 Offshore Block of Mozambique. The Tertiary geology of the Rovuma Basin is characterized by a prograding clastic margin where sedimentation rates peaked during a period from the latest Eocene through the Miocene. Cratonic uplift associated with the onset of the East African Rift resulted in a high volume of siliciclastic sediments being delivered to the northern Mozambique continental margin. The Tertiary sediments were deposited as a tidal dominated outer shore-face delta on a relatively narrow continental shelf. The paleo-continental slope is highly dissected by submarine canyons which funneled the majority of the sediments carried by turbidity currents and debris flows to the deep water lower slope and basin floor environments. The deep water reservoirs of the Golfinho discovery are stratigraphically controlled, but the footwall cutoff of a major thrust fault serves as the up-dip trap.
Seismic interpretation with a high quality 3D survey, and calibration with 11 wellbores has been effective in defining the depositional elements of the Golfinho reservoirs. The deep water deposition can be classified as confined nested channels in large channel belts and unconfined sheet sands. The individual channel belts are highly variable in thickness, and reservoir quality appears to be controlled by the degree of amalgamation, overburden, and sorting. Differential compaction appears to be the primary bathymetric feature that directed subsequent channel belt position and reservoir deposition. The reservoir net-to-gross ratio of individual channel sands varies significantly depending on the location in the channel, and degree of channel belt confinement. The unconfined sheet sands exhibit a simpler seismic character with fan shaped geometries, and uniformly thinner interval thicknesses. Both Golfinho channel belt and unconfined sheet sand reservoirs contain a significant dry gas discovery with world class resource potential.
AAPG Search and Discovery Article #90204 © AAPG Geoscience Technology Workshop, Stratigraphic Traps and Play Concepts in Deepwater Settings, May 14-15, 2014, Rio de Janeiro, Brazil