With its giant DCV Balder and SSCV Thialf heavy-lift/pipe lay vessels, Heerema Marine Constructors brings more certainty to Spar deployment in ultra-deep water
When Shell Exploration and Production drew up the logistics timetable for the record-setting installation in summer 2008 of the Perdido Regional Development Spar in the deepwater Gulf of Mexico (GOM), the company could not have accurately anticipated that pre-installation operations would be confronted by not one, but two major hurricanes and at least two significant tropical storms. Such unsettled weather could have increased the potential for significant delays.
Fortunately, this was not the case, thanks to significantly detailed pre-planning, including comprehensive probability estimates of weather contingencies. The flexibility available from the offshore heavy construction and pipe lay equipment was crucial to Perdido operations, including mooring system setup, installation of seafloor production piping and equipment, and float out and installation of the spar. This flexibility also was evident in placement of the spar’s topsides and drilling and production equipment.
For that and other important reasons, Shell contracted early in the planning stages with Heerema Marine Constructors (HMC) for use of its Deepwater Construction Vessel (DCV) Balder and Semi Submersible Crane Vessel (SSCV) Thialf, along with a support vessel, the M/V Union Manta, for many of the never-before-attempted operations destined for Perdido.
Setting the records
HMC’s Perdido work scope included the following record-setting operations:
- Deepest ever installation of a spar in 7,820 ft (2,384m) of water.
- Installation of permanent suction mooring piles in world’s record water depth of 8,360 ft (2,630 m).
- Installation of production flow lines and pipeline end structures in world’s record water depth at 9,790 ft (2,984m).
- Installation of integrated topsides (new GOM record lift weight at 9,773 short tons (8,866 tonnes).
HMC also installed the spar’s steel catenary export risers (SCR), water injection system, manifold piles and manifolds, electrical submersible pump (ESP) caissons and inlet assemblies.
Because it can marshal the world’s largest dual-crane, heavy lift/pipe lay vessels to any offshore point in the world, HMC has been called upon for installation of more than half of all deepwater spars in the Gulf of Mexico alone. The Balder is adapted for deepwater pipe lay in the J-lay mode for installation of SCRs and flow lines. It also is equipped with the world’s largest mooring line winch for the safe deployment of all known types of mooring lines, including those made of ultra long, large-diameter polyester fiber, such as those used at Perdido. Both the Balder and Thialf boast extremely powerful dynamic positioning (DP) systems for work in the hostile loop currents and eddies found in the GOM and elsewhere.
Installation of the Perdido spar was scheduled to take place during the summer 2008 Gulf hurricane season, which called for meticulous logistical planning and a firm interface among all parties involved, including a number of regulatory agencies.
Heerema Marine Contractors’ semisubmersible crane vessel (SSCV) Thialf engaged in making Perdido spar’s Quarters lift.
The Balder was instrumental in ensuring that when floated out and upended, the Perdido spar hull could be brought to a “storm safe” mooring status in the shortest amount of time. This involved earlier installation of three of the mooring system’s nine-point polyester lines. In fact, the installation sequences for the entire mooring system was optimized by use of a proprietary mooring line hook-up software.
However, short delays were caused by approaching storms and tardiness in the spar’s arrival at the Perdido site, so the flexibility afforded by the multifunctional construction vessel Balder allowed Shell and HMC to interrupt certain flow line and seafloor component installation operations to handle the spar when it did arrive.
Paves way to higher safety awareness
The experience HMC has gained in installing deepwater floating production facilities shows that with the right equipment, the right tools and the right approach, critical installation windows, particularly for deepwater spar installation, can be minimized in duration and the associated risks actually reduced. The company’s flexible, problem-solving approach actually strengthens its uncompromising attention to safety. This was made clear in the fact no HMC lost-time injuries were recorded during the entire Perdido installation sequence.