DOT 2011: Dry Tree Alternatives for Drilling and Production in Ultra Deepwater Gulf of Mexico

Recently discovered ultra deepwater fields in the Gulf of Mexico face challenges to development from subsalt, drilling/completion, and well intervention complexities.

The following is an abstract of a presentation that will be featured at the Deep Offshore Technology International Conference & Exhibition in New Orleans, Oct. 11-13:

Dr. Ming-Yao Lee, Chevron

Recently discovered ultra deepwater fields in the Gulf of Mexico face challenges to development from subsalt, drilling/completion, and well intervention complexities. To deal with these challenges, operators seek cost-effective dry tree options to increase recovery and reduce subsea well intervention cost. In many cases, the depth of the reservoir means a large drilling rig and payload, resulting in the need for more deck space and heavy topsides.

Traditionally, Gulf of Mexico dry tree solutions have been dominated by spars and TLPs in water depths below 5,000 ft (1,524 m). For water depths beyond about 6,000 ft (1,829 m), a TLP becomes cost prohibitive. For large payload systems, especially those requiring large drilling payload, the size of a spar challenges construction, transportation and installation technologies; and requires offshore integration of the topsides with the hull. There is a clear business case to identify, select, and qualify technologies that will enable ultra deepwater field developments using a non-spar dry tree floater (e.g. semisubmersible) with moderate to large drilling and production capabilities.

This paper gives an overview of the ongoing industry efforts, mainly through DeepStar and RPSEA, to mature dry tree semisubmersible designs that are cost competitive with spars in most cases and overcome the size limitations on the spar in other cases. The presentation will discuss two promising hull forms with associated riser tensioning systems, which make use of conventional technologies to the extent possible.

The authors will focus on technically challenged areas and address promising new technologies that may require further qualification before being field application. 

This presentation will be featured at the Deep Offshore Technology (DOT) Conference & Exhibition in New Orleans. It is scheduled for 2 p.m., Tuesday Oct. 11, in Suite D Room 21 of the Hilton Riverside.

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