From Houston (BN): While OTC bubbled along as usual, two Gulf of Mexico projects with multibillion-barrel potential enlivened the scene here last week.
Shell announced plans to install the GoM’s second fpso at its Stones development (~2bboe), while ExxonMobil and Statoil said they will move forward with the Julia subsea tieback project (6bnbbls).
Stones (SEN, 29/19), in 2,896m, will be the world’s deepest production facility and the second fpso in the GoM following the one at Petrobras’ Cascade-Chinook project, which started up last year.
Julia (28/11), in waters just short of 2,200m, will tie back to Chevron’s Jack-St Malo floater which will send production ashore through new pipelines - 245km for gas and 220 km for oil.
Shell and ExMob plan development drilling to start next year and expect first production in 2016. Shell has not disclosed Stones’ price tag. ExMob said Julia will cost $4bn.
Down deep
Both Stones and Julia are Lower Tertiary discoveries, the former in Walker Ridge 508, the latter in WR627. The projects are 42km apart about 350km southwest of New Orleans. The Stones unit covers eight blocks, while Julia five.
The Shell project will start with two subsea production wells to be followed by six more producers. This first phase is expected to have annual peak production of 50,000b/d. Shell operates (60%) for Petrobras (25%) and Eni (15%).
Julia’s initial development phase is targeted for 34,000b/d from six wells.
ExMob has contracted FMC to supply the supbsea hardware - xmas trees, and a manifold - for the six well project. It had said in regulatory filings that it would use FMC-RLSD wellheads unless long lead times forced a switch to GE/Vetco’s MS-700. Shell has a subsea hardware framework agreement with FMC.
Stones is a technological advance, involving the world’s first use of lazy wave steel catenary risers in conjunction with a disconnectable fpso.
‘A key technical challenge for the project will be the integration of the turret and disconnectable buoy with the lazy wave risers,’ a Shell spokeswoman said.
SCR lazy wave risers (SLWR) were a topic of interest at OTC, where technical papers described the approach as a way to support the weight of dynamic pipe or umbilical sections and to isolate the motion of floaters from ultra-deepwater equipment on the seafloor.
SLWR do present design challenges, however, because of their susceptibility to currents pushing against the buoyant subsea wave segment that provides partial support and isolates the motion of the fps from trees. Connecting and disconnecting from a moving fpso turret will be particularly challenging.
Shell said it chose to go the fpso route for Stones because of ‘lack of infrastructure (pipelines), seabed complexity and unique reservoir properties.’ It is more economical to offload oil by shuttle tanker, but a gas pipeline will need to be built, Shell told SEN.
Stones straddles the Sigsbee Escarpment, an 800m dropoff from the Outer Continental Shelf to the Abyssal Plain with strong currents and a soft furrowed seafloor. Shell has not disclosed the ‘unique reservoir properties’ and the spokeswoman declined to elaborate.
ExMob’s push to develop Julia has faced its own challenges, but mostly in the legal arena. Regulators briefly refused to extend development rights before a federal court ruled the government had overreached and ordered the project to proceed.
