The making of an FDPSO In October, 2006, Murphy Oil Corp. subsidiary Murphy West Africa Ltd. issued Prosafe a letter
of intent for the conversion and operation of the world’s first FDPSO. The US $400 million
contract that was signed in November 2007 gave Prosafe responsibility for converting the very
large crude carrier M/T Europe into the Azurite FDPSO.
The vessel underwent conversion between July 2007 and February 2009 at the Keppel Shipyard
in Singapore.
After awarding the conversion project to Prosafe, Murphy selected drilling contractor Nabors
Industries Ltd. for the drilling component of the system. Nabors, which supervised the rig
fabrication, was to provide and erect the drilling rig on the FDPSO such that the completed
vessel would be equipped with a modular drilling package that could be removed and reused
elsewhere when the drilling work on the Azurite field was completed.
Murphy’s decision to go with a new type of floating production system was based in part on the
fact that Azurite would be a fast-track project. With high rig rates and limited availability of
suitable mobile offshore drilling units, the company was in a position to consider less traditional
options that would allow it to achieve first oil in 2009.
After evaluating a number of production concepts, including a spar/FPSO arrangement like the
one used on the Kikeh field offshore Malaysia and a production semisubmersible option like the
one being used on Thunder Hawk in the Gulf of Mexico, Murphy decided that the most suitable
solution was the FDPSO.
Murphy remained schedule-driven throughout the project and worked closely with the other
companies involved to make sure the schedule was kept. One of the keys to success on the
project was the focus on interfaces — interaction between operator and contractors and among
the contractors working together on the project.
Communication and cooperation were critical.
This project marked the first time an FPSO would be developed with a mobile drilling rig.
Because no such project had been undertaken before, the construction of the FDPSO brought
with it a number of significant challenges.
Dealing with those challenges became the purview of William Jacob Management (WJM) Inc. of
Houston.
The company’s initial involvement was straightforward — to determine loading limits for the
deck and hull for Prosafe. When the time came to place the drilling rig on the deck, however,
WJM’s role changed.
According to Trevor F. Smith, technical director at WJM, the unique nature of the project
brought together two specialized groups (an FPSO operator and a drilling contractor) that had
no experience working together. That lack of experience led to construction and installation
challenges when it came time to place the rig on the deck.
“The first concept was to put the rig and all of its equipment directly onto the deck of the vessel,”
Smith explained, “which wouldn’t work because the deck is cambered and can’t support the
drilling structure that way. The rig also needs to have clearance underneath the drilling decks
because the tanker is storing petroleum at the surface, and a buffer is required to allow for foam
firefighting capability. We proposed some concepts, layouts, and ideas that we eventually ended
up building.”
The most critical component of the solution was the concept of a support structure for the rig.
“We took the deck, moved it up three meters (10 ft), and built another deck to support the
drilling structure,” Smith explained. “That was our first work scope, but as the project
progressed, the scope of work continued to change.”
Michael Duffy, president of WJM, said the work his company did addressed what he called the
“gap scope” — “the work that fell clearly under neither the drilling scope nor the vessel scope.”
Running piping throughout the drilling area and into the rig substructure was the next
challenge.
“We took the vessel specification and the rig specifications and had to build almost a cross-breed
between the two to make it work,” Smith said. “It was a bit of trial and error, and there were
challenges because there were schedule concerns, and the inspection authorities had to class the
vessel.”
In the end, WJM designed the rig decks and piping and oversaw their construction in the PT
Citra yard in Indonesia. The rig installation and commissioning were done in Keppel’s Benoi
facility under the supervision of Murphy and Nabors. In a class by itself
DNV’s Singapore Offshore Class Centre carried out the classing exercise. The life extension
program involved assessing global and local strength, fatigue life analysis for critical
connections, and replacement of structural steel as well as preparations for periodical in-water
surveys.
Problems that required solutions during the conversion and classification processes included the
physical arrangement of adjacent process and utilities modules with their associated structures,
such as piping and cabling. Mitigating the effect of motions was also necessary.
DNV also assisted Prosafe in creating a coherent safety philosophy when combining two ongoing
activities that are subject to different regulations. The society examined topics such as defining
accidental loads, shutdown logic, area classification, and fire fighting. These issues were
addressed within the framework of existing DNV offshore specifications and standards with a
certain amount of interpretation and prioritizing.
DNV verified the process plant design guided by the company’s Offshore Standards and Rules as
templates that had been modified according to Prosafe’s specification. The majority of the
topsides equipment also required DNV certification.
In mid-December 2008, the vessel underwent commissioning in the Keppel Shipyard before
beginning its journey to Republic of Congo.
The completed vessel is a spread-moored FDPSO with a storage capacity of 1.4 MMbbl of oil and
a processing capacity of 60,000 b/d of total liquids and 40,000 b/d of oil.
Another in the works In early September 2008, Brazil’s Petroserv SA awarded Sembcorp Marine subsidiary
Sembawang Shipyard Pte Ltd. a contract to convert a 111,567-dwt tanker into a dynamically
positioned FDPSO with extended well testing drilling capability.
When the new FDPSO is completed, it will have a drilling and storage capacity of 300,000 bbl.
The vessel, to be named Dynamic Producer, is to be delivered to the owners in 4Q 2009.
Dynamic Producer Inc. will operate the new DP FDPSO on a long-term charter to Petrobras. The
vessel will work in the Espírito Santo, Campos, and Santos basins off Brazil.