Noble Energy has said it could be sitting of a resource base of up to 100 million barrels of oil equivalent after a deep-water US Gulf of Mexico wildcat came up trumps.
In what was a double score for the US independent, it has also unearthed more pay at another well in the region, an appraisal probe on the Dantzler find.
At the Katmai exploration well on Green Canyon Block 40, Noble hit 154 feet of net crude oil pay, it said on Thursday.
The discovery was made in multiple reservoirs, with 117 net feet found in the Middle Miocene and 37 net feet in the Lower Miocene, it said.
Noble has estimated the size of the find at this well alone to be between 40 million and 60 million barrels of oil equivalent. The Katmai play now has estimated gross resources of between 40 million and 100 million boe, it continued.
The well was drilled to 27,900 feet in 2100 feet of water, Noble said.
"Additional exploration and appraisal drilling will be required to test the remaining upside potential," the company continued.
Noble operates Katmai where it is joined by Ridgewood Energy, with each on 50%.
Noble also said it has hit 122 feet of net oil pay in two high-quality Miocene reservoirs at the Dantzler-2 appraisal probe on Mississippi Canyon Block 782.
The well was drilled to 18,210 feet in 6600 feet of water.
"Gross resources at Dantzler have increased to between 65 million and 100 million boe," Noble said.
"Dantzler has been incorporated into the company's plans in the Rio Grande development area, which also includes discoveries at Big Bend and Troubadour.
"The Rio Grande development remains on schedule, with first production from Big Bend expected in the fourth quarter of 2015 and Dantzler in the first quarter of 2016."
Susan Cunningham, vice president, Gulf of Mexico, West Africa, and frontier region, commented: "Our appraisal programme at Dantzler has exceeded our expectations and enhances the value of the development."