One well watcher said the probe was thought to be “a smallish heavy oil find”, although a Statoil source would not confirm a find had been made, pointing out that the well is still drilling ahead.

If confirmed, Harpoon would be Statoil’s second find in the frontier Flemish Pass basin after Mizzen to the north-west, which holds 100 million to 200 million barrels of recoverable oil equivalent.

Statoil is evaluating the commerciality of Mizzen, and any nearby discovery would add vital critical mass to a development in 1100 metres of water, though a heavy oil find would likely complicate development plans.