Mariner And Eni Make Deepwater Discovery

Mariner Energy, Inc. and its partner Agip Petroleum Company Inc., the U.S. upstream division of Eni SpA, announced a discovery at the Yosemite prospect in Green Canyon Block 516, located in the Deepwater Gulf of Mexico approximately 150 miles southeast of New Orleans.

The discovery well was drilled by Transocean Sedco Forex’s drill ship, Deepwater Millenium in 3,900 feet of water to a total depth of 11,745 feet and encountered multiple hydrocarbon bearing zones. The well was temporarily suspended after casing was run. Mariner, as the operator, holds a 44 percent working interest in the discovery with Agip Petroleum Company holding a 50 percent interest and Noble Drilling Exploration Company holding the remaining 6 percent.

The successful Yosemite exploratory well is adjacent to and will be developed in conjunction with Mariner's previously announced King Kong development project located in Green Canyon blocks 472, 473 and 517, which is owned 50 percent each by Mariner and Agip. A joint development plan is in progress and includes a 16 mile subsea tieback of two King Kong wells and the Yosemite well to Agip's Allegheny mini-TLP. Mariner is operating the development and start-up phases of the project then Agip will become the operator. Production from the three wells is expected to commence by December 31, 2001 at an initial rate of approximately 150 million cubic feet of natural gas per day.