Rational FPSO Hull Design – Why EGINA hull is different
∴ Alexandre Duran ∴
|| Project Management & Engineering || FLNG || FPSO || Naval Architecture & Offshore Structures ||
As a naval architect/marine engineer it's been extremely gratifying to work on a variety of offshore industry projects at forward thinking companies like TOTAL. ?This major IOC entrusted me to design and deliver a completely new, innovative, rational FPSO hull for EGINA project (#eginafpso).
My proudest achievement, EGINA project allowed us to develop an innovative FPSO hull from initial design stage (pre-FEED), literally starting from a blank sheet of paper, through all stages leading to her final delivery to the end client, the offshore operations team.?EGINA project lasted about 10 years – designing, engineering and delivering a new FPSO hull concept is quite a drawn-out task.?Along the way there were many haters, doubters and naysayers but also many lovers, supporters and optimists.?Whatever point of view one might have, everyone has something to say about EGINA FPSO Hull. Here’s a snippet of some of the comments:
However, people are more often curious about EGINA’s hull design concept, asking:
This essay strives to answer some of these questions and ultimately advise on rational engineering design, specifically rational design of FPSO hulls.
Traditionally, FPSO hulls’ have been converted tankers or new-built box shaped barges, each using the same basic design principles of traditional tankers; however, on EGINA we intended to break the mold and derive a hull design based on first principles.? The oil and gas industry has come to accept the acronym for FPSO to stand for Floating Production Storage and Offloading vessel.? In 2010 at the 11th Annual FPSO Congress in Singapore, I made a presentation that proposed that FPSO hull designs could be more rationally thought out, where for example, the O should instead stand for Operations – the end client of the FPSO. ?EGINA hull first considers the comfort, safety and technical requirements of the operators living and working aboard the FPSO.?
Most of the innovation of EGINA hull is not seen but is practical for daily operations and through the life of the FPSO.?EGINA was designed with net improvements that benefit hull stability, strength, storage, ballast, production, safety and even corrosion protection, where only part could be gathered from her hull shape.
Final phases of hull construction at Dry-Dock 3, SHI
We started with a functional hull design that considered reduced buoyancy at the ends.?Ship-shaped hull forms with smaller volumes Fore and Aft act to minimize hull-girder still water bending moments to effectively reduce the bare hull weight. A volumetrically balanced hull shape also offers steady hydrostatic behavior over the FPSO’s operating draft range.?
The stern of a spread moored FPSO can be, for all practical purposes, considered to be forward facing on site, meaning that the environment heads onto the FPSO mainly from the stern to the bow.?This is especially true in West-Africa where metocean conditions are regularly directional; that’s why accommodations are placed Aft and the flare-tower placed Fwd on a spread-moored FPSO.? Notwithstanding my Brazilian heritage, EGINA hull stern is specifically shaped for optimal on-site performance with respect to swell and waves – that’s why the “Brazilian tanga” or “string bikini”.
Calm water model tests revealed that the hull would fishtail under tow.?However, the eddy induced pressure variations were entirely dissipated when towing tests were conducted in an irregular seaway.?EGINA tow was entirely successful and went without a hitch. ?We received much praise from the crew aboard EGINA FPSO who told of enduring minimal motions during the tow and feeling more comfortable than on any other FPSO.
Model testing at MARIN, Netherlands
Critics argue that EGINA hull’s smaller volumes Fore and Aft take away from useful volume inside the hull.?However, replacing the lost volume as in a box-shaped hull would result in that volume still being lost internally to additional ballast required to maintain the required hydrostatic performance.?Furthermore, the added ballast in a box-shaped hull form would significantly increase hull steel weight, further detracting from available storage capacity.
EGINA is the world’s largest FPSO by capacity, able to hold a maximum of 2.3 million barrels of processed oil in its storage tanks. Besides the generous storage, EGINA hull boasts 4 large tanks that are dedicated to the production process, transferring much valuable volume and weight that would normally be topsides, to the hull, effectively improving the stability of the operational FPSO.
Where traditional FPSO hulls store oil parcels in rows (center row for one parcel and side rows for another parcel). In contrast, on EGINA hull, parcels are stored in a checkerboard pattern to allow for quasi-static load balancing between loading and offloading sequences.? Typically, large FPSO hulls are designed to store 2 MMbbl just like on a VLCC tanker. However, due to the dynamic nature of the production process, the same maximum cargo capacity is unnecessary for an operational FPSO because while one parcel is being produced, the other parcel is being temporarily stored or is being offloaded.?EGINA’s 2.3 MMbbl capacity came about due to a specific requirement for the storage segregation of two independent 1 MMbbl parcels while a third is undergoing production. ?An earlier concept of EGINA hull estimated that 2 parcels would require just under 1.8 MMbbl of total storage capacity to effectively produce and transfer 1 MMbbl parcels.?
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Aft end of Egina in Dry-Dock 3, SHI, Korea
But the initial design process to determine the size of a new FPSO hull doesn’t come from stability or storage requirements, we start with what could be called “real estate” properties.? Simply put, we look at the process demands on topsides so that we can fit all the production equipment on the hull deck – we study the surface area requirements as a starting point in a top-down design process.?Transferring the aforementioned process-tanks from topsides to the hull also served to release some valuable topsides “real estate”.?EGINA hull’s “real estate” premise also takes into consideration safe passage of personnel and equipment on the hull deck while also allowing space for material handling and maintenance as well as future expansion considerations for topsides.
Inside the hull we look to extend the life of the FPSO by mitigating corrosion.?The “dry belt” is probably the least known yet most unique feature of EGINA hull.?EGINA’s “oil ballasting philosophy” ties in with the “dry belt” because we forgo the traditional wing ballast tanks along the cargo zone for void spaces along the double-sided hull.?Cofferdams at the ends of the cargo area delimit this “dry belt” so that corrosion is inhibited all around the cargo tanks. ?Traditional FPSO’s have early onset of severe corrosive degradation at internal longitudinal bulkheads due to temperature gradients between cold seawater in wing ballast tanks and hot crude in the adjacent cargo tank.?The ultimate corrosion protection is to avoid a high temperature seawater environment that stimulates corrosive attack through an increased rate of electrochemical reactions and diffusion processes.?These two unique developments, the “dry belt” and the “oil ballasting philosophy”, allowed us to increase the cargo carrying capacity of EGINA FPSO because we are storing less ballast as deadweight.
Egina hull tank construction at SHI with DGM Philippe Allet and EM Jean Basili
Put in a nutshell, the rational design of an FPSO hull should ultimately be based on first-principles of engineering with respect to:
Getting back to comments on EGINA hull, I'm deeply grateful to Total and to my managers who entrusted me with this beautiful task and also thankful to all who’ve made positive comments and contributions.?Hopefully, this brief article on EGINA hull will squash negative thoughts on EGINA hull, however, do feel free to leave constructive remarks. ?
So, why is EGINA hull so different from the other FPSOs in TOTAL's fleet? Perhaps each naval architect that designs an FPSO hull does so based on his/her own personality, philosophy and vision; after all, engineering design is indeed a creative endeavor.
Furthermore, although not patented nor copyrighted, we can only be delighted and honored that major FPSO contractors are copying the basis of this original hull design concept.?
Please leave your comments bellow, tell us what you like about EGINA hull or ask anything.? If you work aboard EGINA FPSO, do tell us how everything is working out and what you think of the hull.
Egina FPSO as seen from the top of the flare tower
N.B.:? Alexandre Duran was the lead Naval Architect on EGINA project, managing many aspects of the FPSO hull design, engineering and construction from start to finish.?After successfully delivering AKPO FPSO hull, Total contracted him to work in France, in early 2009, to develop the EGINA hull concept and was entrusted with the responsibility to manage FEED subcontractors Technip and STX, then onto Nigeria to develop the project specifications and CFT with subcontractor CresTech. Two and a half years later, EGINA project went on stand-by while awaiting the necessary approvals to go forward with the EPCI, a hiatus that led me to work on TEN FPSO project for Tullow Oil in Singapore and then finishing that FEED in time to go open the EGINA project office for the EPCI at Samsung Shipyard (SHI) in Korea in early 2013.?We conducted model testing of EGINA FPSO in Denmark (FORCE Technology), the Netherlands (MARIN) and Korea (Samsung Ship Model Basin), fabricated a third of the hull modules in China (SHRC) and integrated the final topside modules at SHI Nigeria.?
In late 2017, POSH did a fantastic job of towing EGINA from Korea to Nigeria also performing the final tow from SHI-MCI yard in Lagos in late 2018.
On December 29, 2018, Total started up production of EGINA Field, located 150km off the Nigerian coast at about 1,600 m water depth. Today EGINA FPSO proudly boast a daily production rate of 200,000 barrels of oil, contributing about 10% of Nigeria’s daily output.
EGINA FPSO project was truly an international endeavor with amazing
professionals composing a beautiful and complex masterpiece.
Key words:?#TotalEnergies?#Total?#totalupstreamnigeria #Egina?#Petrobras?#NNPC
#EginaFPSOTeam?#oilandgas?#eginafpso?#SHI #SHIMCI #SamsungHeavyIndustries
Lead Structural Designer / Engineer (Engineering/Construction) Looking for new opportunity.
2 年Congrats Alex...
Very interesting paper to avoid some pit falls in FPSO design and follow good engineering practice. I note though, that it requires a few years of development, which is a luxury in the industry we live in.
Managing Director, Zaxpec Energy Ltd
3 年Lovely article Alex.
Project Management
3 年Hi Alex, great write-up. Reading and seeing these photos brought back the wonderful memories of times at SHI yard, Geoje! I also remember how hard you worked to ensure this 'bikini-shaped' hull is a big success. Well done.
Energy Technical Director - SOMWS No.199
3 年Congratulations Alex, very good article. Thank yiu for taking the time to provide more insights on the design. In deed this was greatest FPSO design achivement I have worked with so far. I really enjoyed working with you on this project. Stay in touch