Discoverer Spirit Sets New World Record

Transocean Sedco Forex Inc. (NYSE:RIG) said it has set a new world record for ultra-deepwater drilling when the company's Discoverer Spirit drillship spudded an exploration well in 9,687 feet of water in the Gulf of Mexico for Unocal Corporation (NYSE:UCL).

Blowout prevention equipment was installed and tested after the May 2 spudding, and drilling operations are under way.

The exploration well, on Unocal's Trident prospect in Alaminos Canyon block 903,Discoverer Spirit surpasses the previous claimed industry record of drilling in 9,157 feet of water set offshore Gabon earlier this year.

The Discoverer Spirit utilizes Transocean Sedco Forex's proprietary dual-activity drilling process. Along with Unocal's unique approach to low-cost drilling, dual activity is designed to reduce by approximately 15% the time required to drill exploration wells and up to 40% for production wells. Dual-activity time savings are achieved by performing drilling tasks in parallel steps instead of sequentially with conventional offshore drilling rigs. To date, the Discoverer Spirit has drilled three deepwater exploration wells in the Gulf of Mexico for Unocal, resulting in significant time savings.

Unocal and Transocean Sedco Forex use internal benchmarking to develop a detailed plan for each well to achieve optimal drilling results. Drill site supervisors and contractor personnel aboard the Discoverer Spirit receive the tools and authority they need in order to perform and an incentive to plan rigorously and execute with high efficiency.

Transocean Sedco Forex Inc. is the world's largest offshore drilling contractor with more than 170 full or partially owned, chartered and managed mobile offshore drilling units, inland barges and other assets utilized in the support of offshore drilling activities worldwide. The company's mobile offshore drilling fleet is considered one of the most modern and versatile in the world with 50 semisubmersible drilling rigs (including two in the final stages of construction), 16 drillships and 55 jackup drilling rigs. Transocean Sedco Forex Inc. specializes in technically demanding segments of the offshore drilling business, including industry-leading positions in deepwater and harsh environment drilling services. With a current equity market capitalization in excess of $15 billion, the company's ordinary shares are listed on the New York Stock Exchange under the symbol "RIG."

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company's principal operations are located in North America (Gulf of Mexico region, Alaska and Canada) and in Asia (Thailand, Myanmar, Indonesia, and Bangladesh). The company is also pursuing exploration programs in West Africa and Brazil.