Exploration first started in Senegal in the 1950s with over 140 wells drilled to date.
Previous offshore wells by ExxonMobil, which used to be called Esso, demonstrated there was oil on the continental shelf when it was there between 1968-72.
Deep sea drilling further offshore in the 1970s indicated Cretaceous source rocks, seen extensively elsewhere on West African margin, but for all this there is currently no oil production in Senegal.
In March 2013 Cairn (LON:CNE) farmed-in as operator to three contiguous blocks offshore Senegal (Rufisque Offshore, Sangomar Offshore and Sangomar Deep Offshore) with joint venture partners State-owned Société des Pétroles du Sénégal (PETROSEN) and ASX-listed junior FAR Limited.
The other notable explorer active offshore Senegal is Oslo-quoted African Petroleum.
As operator during 2014, Cairn drilled two wells offshore Senegal, the SNE-1 and FAN-1 wells, discovering oil in both and opening a new hydrocarbon basin on the Atlantic Margin.
The first exploration well, FAN-1 located in 1,427 metres (m) water depth and around 100 kilometres offshore in the Sangomar Deep block, reached a target depth of 4,927 metres and was targeting multiple stacked deep water fans.
The well encountered a substantial oil bearing interval that materially upgraded the prospectivity of the block with a proven petroleum system and a number of deep fan and shelf prospects established.
The second exploration well, SNE-1, located in 1,100 metres water depth and around 100 kilometres offshore in the Sangomar block, was targeting the Shelf Edge Prospect.
Wire line logging of SNE-1 confirmed hydrocarbons in the Cretaceous clastics objective, which is of similar age to oil-bearing sands found 24 kilometres away in FAN-1.
According to Cairn investor relations spokesperson, Linda Baines, the SNE-1 discovery has been recognised as “potentially the largest global oil discovery in 2014”.
In May 2015 a forward programme was submitted to the government of Senegal.
The three-well programme is currently planned to include two appraisal wells on the SNE-1 discovery, which will core and test the reservoir, as well as one shelf exploration well.
Planned also is a 2,000 square-kilometre 3D seismic data acquisition campaign over the Sangomar Offshore and Rufisque Offshore blocks to help fully map the prospectivity of the contract area.
Cairn estimates that the existing two discoveries and the currently identified prospects and leads have a mean risked resource base of more than a billion barrels.
If nothing else investors should be provided an interesting, news-heavy few months as the three planned wells are completed and tested.