Drilled in water depths around 2,684m, the well exceeded a total depth of 8,406m, encountering a gross hydrocarbon column of 188m with 79m of net oil pay.

Steve Bell, President of Exploration and Business Development for BHPB Petroleum, said today: "This is a very encouraging result on a large structure. Of course, it is early days and the result must be seen in perspective. While this is the deepest penetration to date on Chinook, we must have more appraisal data before we can be definitive about the scale of resource.

"Importantly, this strengthens our inventory of BHPB-operated discoveries in the area. With Shenzi, Cascade, Neptune, and Vortex, we have a full appraisal program in place to evaluate and, if successful, create more value by ultimately commercialising these hydrocarbon accumulations."

The Chinook discovery is located more than 300km from the Louisiana coast in Walker Ridge Block 469, 30km south of the Cascade discovery. Drilling began mid January 2003, with the BHPB operated drillship C R Luigs. BHPB owns a 40% interest and is the operator of Chinook with Petrobras owning a 30% interest, with Total and Amerada Hess each holding a 15% interest.

BHPB holds interests in more than 340 blocks in the Gulf of Mexico, where the company is actively exploring for oil and gas. Deepwater projects sanctioned for development include the Atlantis and Mad Dog oil and gas fields, in addition to producing assets at Typhoon and Boris.