Deep-water drilling: efficiency gains

THREE UNIQUE drill-ships can provide up to a 40% improvement in deep-water well construction efficiency, according to their owner, Transocean Sedco Forex. The three identical vessels, Discoverer Enterprise, Discoverer Spirit and Discoverer Deep Seas, are fitted with the firm's dual-activity drilling equipment, described as two complete drilling systems within one derrick. This allows the vessels to carry out some well-construction tasks simultaneously, instead of consecutively. In a typical operation last year, the Discoverer Enterprise attached a blow-out preventer at one well at BP's Thunder Horse field, in the Gulf of Mexico (GoM), while simultaneously cementing a wellhead at another well