However, the vessel’s Beaufort Sea design required some changes due to the Sea of Okhotsk wave regime, the Far East region’s seismic environment and deeper water depths offshore Sakhalin. All of these issues were addressed during the conversion process.

The only platform of its kind, the ABS-classed Molikpaq has been redesigned to withstand the Sea of Okhotsk environment, including storm winds, high waves during open-water season, icing, snowfalls and poor visibility. Broken rubble ice may build ridges up to 25 meters thick in the shallow water. Wave heights can reach as high as 19 meters from peak to trough during a 100-year storm.

The Molikpaq was refitted for both drilling and production service in Russia’s arctic waters. The converted Molikpaq provides all of the required facilities for early production in this remote location, including accommodations, the ability to drill and produce up to 32 wells, an oil export system and gas injection.

A significant new component of the Molikpaq is its unique substructure, incorporating the "Spacer," which was designed and built in Russia. The Spacer is necessary for the Molikpaq’s operation in waters deeper than its initial 15-to 20-meter Beaufort Sea design.

ABS had the added advantage of its ability to work with the Russian Maritime Registry (RMRS) due to the reciprocal relationship existing between these two bodies. This arrangement proved valuable during the fabrication of the Spacer, particularly relative to codes, standards and material specifications. SE, therefore, benefited from the consensus reached by the two Classification Societies on a number of specification issues.

When built in the early 1980s, ABS classed the Molikpaq as a Mobile Caisson Drilling Unit. Economic advantages from both an insurance and lenders’ perspective encouraged the Sakhalin II team to maintain the Molikpaq’s status as a classed vessel. Following a review of classification alternatives, ABS continued as the Classification Society because of its familiarity with the vessel. As an independent third party, the ABS review instilled assurance to lenders and confidence among Russian authorities that Molikpaq meets quality standards in construction and is a suitable drilling/production platform.

ABS carried out a full design review for the Molikpaq conversion and its substructure to ensure its stability. ABS also verified SE’s free-floating mating procedure of the Molikpaq and Spacer. The mating took place during May 1998 in deep waters near Okpo, South Korea, where Daewoo Heavy Industries completed the Molikpaq conversion activities. The combined Molikpaq and Spacer weight is 51,600 metric tons, with the Molikpaq covering an area that includes two football fields.

Molikpaq maintains its class as an A1 Mobile Offshore Drilling Unit, now inclusive with production facilities, which also are ABS classed. During the conversion process and throughout the hook-up and commissioning phase, ABS assisted Sakhalin Energy in optimizing the Molikpaq’s performance as a production/drilling platform in a cold weather environment.

ABS activities included checking all process components to ensure that SE’s expectations for rating pressures and production volumes were achieved. Inherent in this review process was the certification of the vessel’s safe operation according to ABS Rules and Panama Flag Administration regulations. ABS acted on behalf of the Panamanian government, also certifying tonnage and load line issues for the tow from Okpo to the P-A site.

Because schedule was so essential to the project’s success—given weather windows for the Molikpaq’s transport from Okpo to the P-A site—ABS remained flexible, reviewing critical path components without loss of days or downtime to the project.

The second significant component in the Vityaz Production Complex is the FSO. The "Okha," named after a city on the northern end of Sakhalin Island, is designed for tanker offloading for six months of the ice-free season, from July through December. "Okha" took first oil from the Molikpaq on July 7. Built at Daewoo in Okpo, "Okha’s" dual capability as a tanker allows the vessel to deliver its last production load directly to market.

"Okha" is one of the few vessels worldwide with this dual capability, and as such, retains its ABS class as a trading tanker. The owners of "Okha," therefore, requested ABS’ SafeHull analysis for tankers, without obtaining special consideration and reduced scantlings for on-site, benign operations in the FSO mode. ABS’ SafeHull technology assesses a vessel’s hull structural strength in terms of yielding, buckling and fatigue.

The vessel is ice-classed "D0" for its reinforced bow, allowing it to push through "young" or "light" ice. This capability allows the vessel to remain on site into the early winter to maximize oil production, without risking its ability to reach open water. The vessel’s reinforced shell plating provides additional protection for the arctic environment.

In December, "Okha" will disconnect from its SALM Buoy, leaving the field for the winter and returning when the ice departs in late spring. In the interim, the SALM will be ballasted and laid into a dredged recess in the seabed.

SE will use the FSO for the duration of Phase I production, after which it will return to its owners for future trading as a conventional tanker. "Okha," a Suezmax double-hull tanker, has 12 cargo tanks with storage capacity of 1 million barrels. The 157,200 DWT tanker can accommodate tandem offloading from the stern and is equipped with a double-carcass offloading hose. The vessel also features a 15-metric ton offshore crane and one of the world’s largest offshore metering skids: three 25,000 barrel/hour turbine meters for a total capacity of 75,000 barrels/hour.

The ABS class notation for "Okha" is A1 Circle (E) Oil Carrier Ice Class DO, FSO, meaning the vessel is disconnectable. The Circle-E notation addresses temporary mooring aspects while operating as a tanker; the FSO notation covers mooring during FSO operations. The ABS process for assigning class on a vessel of this nature includes technical plan review for structural issues, including a SafeHull analysis, stability, structural fire protection, machinery, surveys during construction and periodic surveys during the life service.

In addition to the technical aspects of certifying "Okha," ABS coordinated discussions between the Daewoo shipyard, which was responsible for securing vessel classification, and Sakhalin Marine, the owner of "Okha" and responsible for obtaining the FSO notation.

The certification process called for extensive interface and flexibility in scheduling to conduct vessel tests and to resolve outstanding issues without duplication of work. Further, ABS could not recommend the FSO notation until the vessel was on site. To facilitate this approval without unnecessary delays to the July 1999 production start-up, ABS verified as many issues as possible, including testing of piping systems and use of the FSO mode oily water separator, prior to the vessel’s departure from Daewoo.

In addition to class, ABS provided statutory certification such as Safety of Life at Sea (SOLAS), load line and tonnage certificates on behalf of the Bahamas Flag Administration. The SOLAS certification includes the availability of foam for the cargo hold and main deck as a fire protection measure. Load line issues for "Okha" address its operations as an FSO. "Okha" is certified to maintain a draft of up to 17 meters during loading and unloading crude.

The Molikpaq was installed on the P-A Field in September 1998 and development drilling began in November 1998. The SALM and a two-kilometer pipeline from the Molikpaq to the SALM were installed during 1998, and "Okha" was on site in June 1999.

Sakhalinmorneftemontaz (SMNM) completed the process hook-up and commissioning onboard the Molikpaq in July 1999. The SALM, measuring 38 meters tall and 6 meters in diameter, and the two-kilometer pipeline to the SALM, ties in to the FSO. Molikpaq production flows through the subsea pipeline to the SALM riser piping and swivel. The oil then passes through a submerged flexible loading hose to the bow of the FSO.

An ice-breaking support vessel assists "Okha" and the entire Vityaz Production Complex. The multiservice vessel—essential to efficient operation of the FSO—also carries supplies to the Molikpaq during the winter.

SE is a company established for implementation and development of the Sakhalin II Fields. The shareholders in SE are: Marathon Sakhalin Limited, Mitsui Sakhalin Holdings B.V., Shell Sakhalin Holdings B.V. and Diamond Gas Sakhalin B.V. (Mitsubishi).

ABS classed the Molikpaq and "Okha" vessels according to the ABS Rules, as developed by ABS with assistance from experienced professionals worldwide. The ABS Rules and their application are designed to support industry safety and innovation. Industry dialogue in the early design phase, such as on the Sakhalin II project, facilitates flexibility for compliance, while ensuring optimum performance in frontier waters.

In addition to the platform, FSO and tanker classifications, ABS offers classification for floating production units, including tanker-based production storage and offloading vessels; and other floating production systems without storage, such as semisubmersibles, spars and tension leg platforms. Independent third-party classification services during design, fabrication, installation and ongoing periodic surveys represent an investment in the operational life of offshore facilities.

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