The Onyina-1 well was drilled to explore a large, high-risk, Campanian prospect between the Tweneboa and Jubilee fields in the northeast of the Deepwater Tano Licence. It intersected 49 metres of good quality sandstone reservoir, on prognosis, however they were water bearing at this location.
The Sedco-702 dynamically positioned semi-submersible rig drilled Onyina-1 to a total depth of 2,730 metres in water depths of 828 metres. On completion of operations, the rig will move to the Jubilee Unit to assist in the preparations for first oil later in 2010.
Tullow (49.95%) operates the Deepwater Tano licence and is partnered by Kosmos Energy Ghana (18%), Anadarko Petroleum (18%), Sabre Oil & Gas (4.05%) and the Ghana National Petroleum Corporation (GNPC) (10% carried interest).
Commenting today, Angus McCoss, Exploration Director, said:
"The negative test of the Campanian reservoirs in the Onyina prospect enables further refinement of our exploration and relinquishment strategy offshore Ghana. Good quality Campanian reservoir sands were found as predicted, however the lack of hydrocarbons at this location highlights the high risks of charging and trapping oil in this secondary play.
Our main focus remains on the lower risk primary play, the deeper more prospective Turonian reservoirs, where we have had such outstanding success with Jubilee, Tweneboa and Owo."