UK-based Ophir Energy has encountered a 182m gas bearing column in mid-Miocene aged sands at the Tonel-1 well in Block R, offshore of Equatorial Guinea.
The company encountered 117m of net pay when drilling the well, using the Eirik Raude semi-submersible rig, to 3,072m in a water depth of 1,599m.
This is the first in a three-well drilling programme at Block R, which is due to be completed in September.
Ophir said the discovery has an estimated mean in-place resource of 177 million barrels of oil equivalent and a recoverable mean resource of 133 million barrels of oil equivalent.
Nick Cooper, Ophir Energy CEO, said: "Tonel represents the fifth and largest gas discovery on Block R to date and importantly represents a significant step towards the commercial threshold volumes required for a second train of LNG from Equatorial Guinea," said Cooper.
"The drilling programme will now return to the vicinity of our earlier Fortuna-1 discovery."
The Tonel discovery can now meet the minimum commercial threshold for a second LNG train on Bioko Island.