January 2016
Oilfield Technology |
67
to the pipeline end termination, and tensioned
nearly vertical by a buoyancy can suspended in
the waterline (below the influence of waves and
currents), with a flexible jumper connecting the
rigid riser to a nearby floating production facility.
The invention of free standing hybrid risers,
in use primarily in West Africa and more recently
in offshore Brazil and the Gulf of Mexico, offers
distinct improvements over other riser systems,
such as reduced fatigue load on the riser (riser
decoupled from vessel motions), reduced load
transferred to the platform (lower payload),
and a construction and installation schedule
autonomous of the platform. Additionally,
FSHR are ideal for fields with severe metocean
conditions, sour service requirements, and a large
number of risers being tied-back to the facility.
While today’s FSHR designs may offer
many advantages over other riser systems for
deepwater fields, they too face challenges that
create an economic drawback, as the installation
requirements are time intensive, extremely costly
compared to other riser concepts, and require
three or more vessels to complete.
A recent paper presented at SPE Offshore
Europe compared the deepwater riser cost
breakdown for different riser systems for a
six riser development in water depths of 2000 m.
The comparative costs are:
Steel catenary riser: US$152 million.
Lazy wave steel catenary riser:
US$176 million.
Free standing hybrid riser: US$452 million.
The higher cost of FSHR is mainly due to three
factors:
Cost of material and fabrication for the
hardware.
Cost of transport and installation.
Cost of installation vessel mobilisation and
demobilisation.
GMC has developed a connected FSHR
solution that is designed to provide significant
Capex savings. A key part of this is the
development and qualification of the mechanical connector
product.
Making a connection
A mechanical connector product line for risers and
flowlines, called Intelligently Connected Pipe (ICP™),
has been developed to meet the emerging needs of the
deepwater SURF market, placing particular emphasis on
reducing the high costs of riser installation. By supplying
pre-manufactured riser joints with connectors on each end
of the rigid pipe it eliminates the need for offshore welding
and high cost installation and lay vessels.
The solution enables the operator to more quickly
and cost-effectively produce and manage well production
by allowing local assets to be used in SURF, rather than
waiting for the large international contractors to plan the
mobilisation of assets from distant shores. Traditional
welded lazy wave steel catenary riser (LWSCR), free
standing hybrid riser, and flexible riser technologies are
time consuming to manufacture as well as to install.
Figure 2.
GMC connector.
Figure 1.
Deepwater riser cost breakdown.
