Offshore staff
HOUSTON -- John Murray, director of technology development for FloaTEC, presented a comparison of deepwater production systems at the Deep Offshore Technology conference Tuesday, Nov. 28.
The presentation included an analysis of three deepwater production options, including a tension-leg platform (TLP), spar, and semisubmersible. "It's really just a matter of choice when you're looking at water depths less than 5,000 ft," Murray said of production system selection, but he cautioned that in deeper waters, an in-depth analysis of the limitations and benefits of each system is critical.
Facts and figures aside, Murray said, "In my experience, it seems the propensity of a company is to choose a production system based on personal experience."
Murray explained why sticking to a standard choice can be an unwise move. The analysis he presented evaluated production systems based on performance, not propensity.
For the comparison presented, Murray said, design tools were used to optimize each type of production system so as to make a direct comparison. For this analysis, Murray introduced a dry-tree semi concept called the ESEMI II, which is a semi with a heave plate underneath the platform. The hydrodynamic model is still under development, Murray said, but the concept was evaluated for the purpose of conducting this comparative study using a dry-tree semisubmersible.
The comparison used a Gulf of Mexico operating environment with 60 MMb/d of oil production and with 20-person accommodations. The rigs were outfitted with hydropneumatic tensioners on top tensioned risers. Parameters also included the ability to work in 4,700 ft water depth.
Extensive analysis builds a case for the dry-tree semi, Murray said. The semi yields small in-place motions, provides a large open deck, allows for dockside hookup and commissioning, offers water depth insensitivity, requires minimal at-sea commissioning, and offers ready redeployment.
11/29/2006
