Angola Pre-salt Development

New Wave Media

July 31, 2013

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Few people acknowledge this but the exploratory campaign that led to the 2006 discovery by Petrobras of the Tupi (renamed Lula) field, at the Santos Basin in Brazil was partially triggered by early pre-salt finds in West Africa and the knowledge that the petroleum systems on both sides of the South Atlantic were similar. With the experience gained from drilling Lula and other subsequent pre-salt discoveries in Brazil, interest returned to the pre-salt in Angola’s conjugate Kwanza-Benguela and Namibe Basins. The common origin of the reservoirs and similar tectonics increased the belief that similar plays should exist in Angola.

The Santos Basins is a major hydrocarbon basin along Brazil’s Atlantic coast. The oldest syn-rift (pre-salt) discovery underlying the extensive regional salt layers was 1978’s Linguado field in the Campos basin, which was not extensively explored at the time due to technological constraints and lack of economic viability. Not until 2006, and the discovery of the Lula field in the Santos Basin was the scale of the potential reserves appreciated. Since the success of the Lula field, exploration and production of pre-salt plays has tremendously increased Brazil’s offshore reserves. Other pre-salt discoveries followed in both the Campos and Santos basins, culminating with the recent discovery of the massive Libra field, with an estimated 8 to 12 billion barrels boe in reserves.

In comparison, the development of pre-salt plays along Angola’s offshore basins has only slowly taken off. Despite proven hydrocarbon potential, the pre-salt plays potential has hardly been explored, much less developed. In 1992, the Falcão-1 well reached the pre-salt reservoir, encountering reservoir-quality carbonates. In 1996, the Baleia-1 well also reached the pre-salt and discovered an estimated 1-billion-boe. Recently exploration campaigns increased in Angola with the 2011 discoveries of Cameia, by Cobalt, and of Azul by Maersk Drilling. As the potential for more pre-salt reserves was ascertained in Angola’s Kwanza-Benguela basins, and the Namibe basin, a major survey effort is being undertaken using the latest seismic acquisition technology to help locate more offshore deepwater reservoirs.It's also important to note that pre-salt reservoirs in Angola are not necessarily as far from shore and as ultra-deep as in Brazil.

The geological characteristic of the Kwanza-Benguela basin area is very complex. Angola’s offshore petroleum systems are part of the South Atlantic salt basin geological province. In West Africa, this extends from the southern margin of the Niger Delta in the north, to the Walvis Ridge volcanic high in the south. The offshore basins of other West African nations in this area share similar structural and stratigraphic characteristics, due to their common origin during Late Jurassic to Early Cretaceous rifting era. The common origin and development of these basins is also shared with those of the corresponding area in Brazil, on the opposite margin. The geological history of these basins is commonly divided by basin development stages, each characterized by particular petroleum systems.

Angola is racing to increase its oil production and maintain its position as Africa’s second largest oil producer, more than a year after it signed production sharing agreements for acreage offered in the limited international bidding round in December 2011 for access to pre-salt acreage in the Kwanza basin. Angola’s oil sector entered 2013 with a scenario with production close to record 2008 levels due to starting new exploration and overcoming technical difficulties at other plays. Twelve major and super-major oil companies such as Statoil, BP Angola, Eni Angola, Esso Angola, Galp Energia, Maersk Oil, Petrobras, Total Angola, Sonangol, Chevron, Cobalt International Energy , and ConocoPhillips participated in the pre-salt bidding round. Some of these have reported progress in exploration. The prospect for Angola’s pre-salt development is excellent and with new seismic,drilling and production technologies geared for the pre-salt already at hand, new and significant discoveries can be expected in the near future. An added benefit is that the pre-salt oil in Angola is not only light but also sweet (low sulphur content) and does not require much refining.

 

 

 

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Paschoa, Claudio
Claudio Paschoa is Marine Technology Reporter's correspondent in Brazil.
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