Tests have indicated “that future production well deliverability will be in excess” of 20,000 barrels of oil a day, the company said in a statement.
The Hyedua-2 appraisal well, which lies in the Deepwater Tano license, was drilled to appraise the Jubilee field, the company said.
Tullow plans to invest about $3.2 billion to develop Jubilee and produce the first oil there in 2010.
Tullow is targeting about 4 billion barrels of oil and gas resources in the Gulf of Guinea off Ghana and Ivory Coast.
Kosmos Energy LLC, Ghana National Petroleum and Anadarko Petroleum also hold stakes in the project.