Geologically speaking, "pre-salt" refers to a reservoir that was deposited prior to a layer of salt. In the Southern Atlantic, the salt layers were deposited more than 100 million years ago in a space formed by the geographical separation of the American and African continents.
Salt being a good sealing element, the source rocks – i.e. the organic matter or kerogen – deposited during the opening of the South Atlantic basin, also called the "rifting process", ended up enclosed in sealed, temperate, and pressurized formations, and were then later transformed into hydrocarbons (oil and natural gas).
Therefore, even though "pre-salt" operations were so far concentrated in the Gulf of Mexico and offshore Brazil along the western margin of the South Atlantic – making Petrobras and its partners, including Vallourec, precursors in "pre-salt" operations. A similar geological structure is expected offshore West Africa, in the conjugate eastern margin of the South Atlantic. In 2008, Brazil's proven reserves were up to 14 billion BOE, and it is considered to be up to 23 billion BOE thanks to pre-salt reservoirs by 2030, which is a lot at stake in spite of the technological challenges involved.
The potential pre-salt reserves, the experience acquired offshore Brazil, the latest technology developments, and the rising global demand in Oil & Gas thus made Oil companies and Vallourec already looking at salt-linked challenges to be overcome in offshore west-African countries, among them Gabon & Angola.
Regarding to tubular supplies, these extreme conditions must be studied thoroughly at a very early stage by both the operator and the OCTG tubular supplier in order to get the right metallurgy and connection chosen to meet efficient drilling & production objectives: enabling the well architecture to maximize production, avoiding casing collapse, enabling the surface or subsea equipment to withstand the weight of the whole casing column, and avoiding corrosion to set in.
Through its local production capabilities at Vallourec do Brasil (VB) in Belo Horizonte and by efficient coordination of local and worldwide R&D, Vallourec naturally became the key partner for pre-salt development. A dedicated organization was set through the VPP (Vallourec pre-salt Project) with the objective to reduce time to market.