Pre-Salt Geology & Exploration History

What is Pre-Salt?

"Pre-salt" refers to geological formations that lie below the salt layer in sedimentary basins along the South Atlantic margins of Africa and South America. These formations were deposited during the Aptian age (approximately 113-125 million years ago) when the supercontinent Gondwana was rifting apart, creating shallow-water environments where carbonate rocks accumulated. As the South Atlantic opened, thick evaporite (salt) sequences were deposited on top, sealing the underlying carbonates.

In Brazil, the pre-salt play has been transformational — discoveries like Tupi/Lula (2006, estimated 8-12 billion barrels recoverable) and Búzios in the Santos Basin made Brazil a top-10 global oil producer. The geological premise for Angola's Kwanza Basin exploration was that the same pre-salt system should exist on the conjugate African margin — and Cobalt International Energy's 2012 Cameia discovery proved this thesis correct.

Kwanza Basin Pre-Salt Characteristics

The pre-salt reservoirs in Block 20/11 are Aptian carbonate mounds that formed over basement highs, creating a "string of pearls" fairway along structural ridges. The reservoir quality varies across the fairway — some accumulations are oil-dominated (like Cameia), others gas-condensate dominated (like Zalophus), reflecting variations in burial depth, thermal maturity, and hydrocarbon migration pathways.

Cobalt estimated 1.3 billion barrels of gross resources across Blocks 20 and 21 from 7 discoveries in 8 wells (88% success rate). Sonangol's estimates for individual accumulations indicated in-place resources of 813 MMboe, 313 MMbc, and 2.8 Tcfg. The Kaminho development targets the two most commercially attractive accumulations — Cameia and Golfinho — for the initial 70,000 bpd development.

Seismic Imaging Challenges

A persistent challenge in the Kwanza Basin pre-salt has been sub-salt seismic imaging. The thick, deformed salt layer distorts seismic waves, making it difficult to image the underlying carbonate reservoirs with precision. This was a contributing factor to the mixed commercial results during Cobalt's exploration campaign — some wells encountered good reservoir quality, others were disappointing. Modern seismic technologies including broadband acquisition, reverse time migration, and full-waveform inversion have progressively improved imaging quality, supporting TotalEnergies' ongoing exploration on Block 20/11 (including the Grenadier-1 well).

For the future potential of pre-salt exploration in the Kwanza Basin, production context, and strategic outlook, see our dedicated pages.