The Heidelberg appraisal well in Green Canyon block 903 is located about 2km from the Heidelberg discovery well was drilled to a total depth of approximately 30,440ft in water depths of about 5,260ft.
Eni found the oil water contact 213m deeper than the previous well, indicating a larger field extent than previously considered.
Estimated recoverable resources could reach 200 million barrels of oil, Eni said.
The group is evaluating well data to accelerate the overall sanctioning process for the project.
Anadarko operates Green Canyon block 903 with a 44.25% working interest.
Co-owners in the block include Apache Deepwater LLC, a subsidiary of Apache Corporation (12.5%), Eni (12.5%), Statoil (12%), ExxonMobil (9.375 percent) and Cobalt International Energy (9.375%).
