GULF OF MEXICO

David Paganie • Houston

Shell has made an oil discovery at the Appomattox prospect in Mississippi Canyon block 392. Transocean's semisubmersibleDeepwater Nautilus drilled the well.

The discovery was drilled in 2,200 m (7,217 ft) of water depth to TD of 7,643 m (25,077 ft) and encountered 162 m (530 ft) of oil pay. A follow-up appraisal well was drilled to 7,910 m (25,950 ft) and encountered 116 m (380 ft) of oil pay. A second sidetrack was undertaken and further drilling in the area is planned for later this year to confirm the field's resource potential. Partner Nexen says the well results exceed pre-drill estimates.

Appomattox is the third discovery in the area following early discoveries at Shiloh (Shell 80%, Nexen 20%) and Vicksburg (Shell 75%, Nexen 25%), which were drilled in 2003 and 2007, respectively. Development planning for Appomattox is under way, and may include Vicksburg located about 10 km (6 mi) east of the discovery in DeSoto Canyon block 353. Shell operates Appomattox with an 80% working interest and Nexen holds the remaining 20%.

Meanwhile, delineation of the Vito discovery continues, with the first appraisal well encountering more than 600 net ft (183 m) of "high-quality" oil pay in subsalt Miocene sands, partner Anadarko says. The sidetrack, drilled to 31,000 ft (9,449 m) TD in 4,050 ft (1,234 m) of water, is in Mississippi Canyon block 940, more than 1 mi (1.6 km) from the discovery well in Mississippi Canyon block 984. The discovery well was drilled in mid-2009 and encountered more than 250 net ft (76 m) of oil pay, Anadarko reports.

A second appraisal well is planned for later this year. Vito, estimated to hold greater than 200 MMboe, could be developed as a stand-alone project, pending further resource evaluation.

Anadarko holds a 20% working interest in the block and was the initial operator of the Vito discovery. Shell operates Vito with a 55% interest and Statoil holds the remaining 25%.

In other GoM deepwater news, Chevron has signed a letter of intent with Pacific Drilling for the drillshipPacific Santa Ana. The vessel will apply dual gradient drilling technology, Pacific Drilling says.

The vessel, under construction in South Korea, is to be capable of drilling in 12,000 ft (3,658 m) of water and to more than 35,000 ft (10,668 m) of well depth.