Gyrfalcon: World's First 15K Subsea Development
Authors: Byers Robert L. , Trevitt Richard E. , Philliber William R. 
Published: October 2008

The recently completed Gyrfalcon subsea development project in Green Canyon Block 20 is the world's first 15,000 (15k) psig subsea system and had many industry firsts associated with its development. Among those were manufacture and installation of the worlds first 15k subsea tree, a record 12,200 psig rated 6" (nominal) flexible riser, a 15k rated umbilical and 12,200 psig rated flying leads. Other firsts included the first 15k rated continuous methanol injection system, a dome charged 15k subsurface safety valve and the first 15k subsea frac-pack completion conducted in the Gulf of Mexico. What is perhaps even more unique is that these firsts were accomplished by a small independent operator, on a marginal field, under very tight budget restraints.

Overview

The project was a 2.9-mile single well tie back of a known discovery in 880' of water. Bottom hole pressure had been recorded at 14,700 psig at a depth of 17,850'. Based on this data, the design SITP of the well at the tree was 12,200 psig. What made the project unique, besides the technical firsts associated with it, was that it was undertaken by a small independent operator with limited staff. This problem was managed through the use of just three key contractors for the project; Total Offshore Production Systems (TOPS), which provided all of the subsea hardware, installation, project management and engineering on a fixed-price basis, Applied Drilling Technology, Inc. (ADTI), which provided engineering and project management for the completion, and Shell Offshore Inc., which managed all host platform process modifications.

Technical and commercial risk on the subsea equipment was taken by TOPS. This allowed the operator more comfort with the technical challenges of the project, as well as permitting aggressive schedule and cost goals. Shell Offshore Inc. managed process modification to the platform on a cost-shared basis, which helped to manage interface issues and maintain cost control on the facilities side.

The project was initiated in February of 1998 and first production was streamed on December 10, 1999. Actual first production could have been in August 1999, approximately twenty days behind schedule, but drill rig blow out preventer (BOP) problems and loop currents forced a move of the original completion rig off the well. A rig did not return to the field until November 1999. Subsea hardware and installation costs were on budget and on time. The original turnkey budget was $18.0 mm and final cost, including scope changes, was approximately $18.3 mm. Completion costs were higher than anticipated due to high rig rates, rig BOP failures and loop current issues. Final completion costs are estimated at $19 mm. At the time of this writing, the well has been on production for approximately 70 days.

Project Management and Contracting Philosophy

Gyrfalcon was originally drilled in March, 1997 by Shell. The GC-20 #1 discovered high-pressure gas (14,700 psig Bottom Hole Pressure) in a single sand at approximately 17,850' in 880-ft water depth.