Unocal Extends Mad Dog Field with Appraisal Well

Unocal said that an appraisal well drilled on the deepwater Mad Dog Southwest Ridge in the Gulf of Mexico encountered significant hydrocarbon pay. The discovery was further delineated by three sidetracks.

The original hole was drilled to a total measured depth of 22,890 feet from Green Canyon 826 to downdip targets in the adjacent Green Canyon 825 block. The blocks are located in approximately 5,000 feet of water.

The well and sidetracks were designed to test the previously undrilled southwest flank of the field. The penetrations individually encountered up to approximately 300 feet of net oil pay in the early Miocene section and found hydrocarbons some 700 feet deeper on the west flank of the structure than previously encountered.

The resources associated with these appraisal wells could either be produced through spar development wells or future subsea tie-backs.

"We are pleased with the results of this appraisal program which has extended the limits of the Mad Dog field," said Joseph H. Bryant, Unocal president and chief operating officer.

The Mad Dog field began production in January 2005 from Green Canyon block 782. Gross field production is currently about 30,000 barrels of oil per day from two wells.

Unocal owns a 15.6 percent working interest in the Mad Dog unit, with net interest after royalty of 13.3 percent. BP is the operator with a 60.5 percent working interest, and BHP Billiton owns a 23.9 percent working interest.

The Mad Dog appraisal was drilled from the Discoverer Spirit drillship, which is under contract to Unocal. The ship has moved to drill the Knotty Head prospect on Green Canyon block 512. The ship is then scheduled to drill the St. Malo #3 appraisal well on Walker Ridge block 677. At the completion of the St. Malo well, the ship will be subleased to another company for the remainder of its lease term. Unocal's commitment to the Discoverer Spirit terminates in September 2005.

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