Preliminary estimates suggest the find contains between 9 and 19 million barrels of recoverable oil equivalents.
The resource estimate for the find was originally seen to contain between 125 and 400 million barrels of oil equivalent.
The well, combined with two follow-on development wells at Horn Mountain Deep, may be capable of producing an aggregate of 30,000 barrels of oil equivalents per day (boe/d).
Transerv executive director Stephen Keenihan described the results as outstanding because they extended the known parameters of the gas at Warro, both at depth and laterally.
The drilling campaign is being operated by VNG Norge AS using the Transocean Arctic semi submersible drilling rig with partners Spike Exploration Holdings AS, Pure E&P Norway AS and Faroe.
The Erha North Phase 2 project is a deepwater subsea development operated by ExxonMobil's subsidiary, Esso Exploration and Production Nigeria Ltd.
The Jacana Field is located southwest of the Tigana oil field, following the same fault trend, and appears to be a combination structural-stratigraphic trap, GeoPark said.
The discovery well, Zohr 1X NFW, was drilled to a total depth of about 4,131 m and hit 630 m (2,067 ft) of hydrocarbon pay.
Zohr 1X NFW was drilled to a total depth of about 4,131 m (13,553 ft)) and hit 630 m (2,067 ft) of hydrocarbon column in a carbonate sequence of Miocene age with excellent reservoir characteristics (more than 400 m of net pay), Eni said in a news release.
Wireline logs indicate a gross oil-bearing interval of about 23 meters at the top of the Ungani Dolomite section in the well, Buru Energy said.