The Horn Mountain field is a deepwater Gulf of Mexico development in 5420 ft water depth located 100 miles south of New Orleans in Mississippi Canyon Block 127. BP is the operator with 67% interest, and Occidental owns 33%. The field was developed with a dry tree spar installed in June of 2002, at that time the world’s deepest dry tree production platform.  Alliance Engineering of Houston was the topsides engineering contractor responsible for engineering, design, procurement and construction support. The platform is a full processing facility with 14 dry tree wellslots, accessed by workover/completion rig with sidetrack capability. Platform nameplate capacity is 65,000 BOPD and 70 MMscfd, together with 40,000 BPD water injection.

The project made use of lightweight design technology to improve project economics and enhance schedule, and was successful on both counts. Topsides loadout was accomplished 19 months after project sanction, enabling first oil to be achieved 18 months ahead of the original project schedule, and 39 months after initial discovery. The topsides incorporated lightweight design practices to enable the process facility to be installed as a single module 4450-ton lift within the capacity of Heerema’s Balder SSCV. The single-module topsides design minimized fabrication costs and offshore construction, enabling platform hookup to be completed within 28 days after offshore mating. Despite moderate reservoir reserves and the record-setting water depth, the combination of capex savings and accelerated schedule enabled Horn Mountain to achieve total project payout 11 months after startup.