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Offshore Oil Production

In the beginning, oil simply welled up from the earth. Thousands of years ago, humans started using oil and its residues. In Mesopo- tamia, people applied naturally-occurring earth pitch to make their reed boats watertight. In modern times, the history of commercial oil production did not begin until the 1850s. Surprisingly, this hap- pened in several different regions simultaneously: in Dithmarschen in northern Germany, in the US. state of Pennsylvania, and in Poland. For roughly a century, oil was solely produced from inland wells. Then, in the 1950s, pioneers ventured out into the seas. Thus the history of offshore oil exploration is short by comparison.

For several decades, oil platforms were simply set down onto the bottom of the sea. In general, we associate offshore oil drilling and production with the concept of the jack-up rig, an oil platform sitting atop a lattice-type structure anchored to the seafloor. Jack- up rigs are a standard solution for water depths up to 130 metres even today. Other, more recent developments are platforms with a solid concrete base, or semi-submersible designs that can be de- ployed in deep water.

In 1995, the Norwegian enterprise Aker Kvaerner completed the world’s largest offshore drilling platform to date. Named Sea Troll, this concrete deep-water or “Condeep” structure is best de- scribed as a huge tank with four concrete pillars extending upwards. The drilling platform, nearly 500 metres in height, was anchored

ceptions from the rule. “Most FPSO solutions are converted tankers. After their decks have been cleared of all redundant parts, the required equipment is installed.”

The second most important feature for trouble-free, safe operation is the mooring system. An FSO or FPSO unit must be anchored in place reliably so its movements in the water remain predictable. The technology preferred today is a sin- gle-point mooring (SPM) system. Maritime engineers cate- gorize this technology as a “dual system” because it consists of anchoring and loading/unloading equipment. Advanced FPSO vessels feature an internal turret mooring system and an integrated anchoring system. The anchor cables are at- tached to the revolving turret located in the centre or bow of the ship. The FPSO is loaded through a riser coming from the wellhead that attaches to the underside of the turret.

The third main component is the production plant, which consists primarily of separators for separating oil, water and gas, treating the produced water, and separating the gas from the oil. But the work of Trident Consultants is by no means limited to offshore equipment and maritime ma- noeuvrability of FPSOs. The production facilities themselves,


Trident Consultants joined the Germanischer Lloyd Group in May 2008. The company has offices in London, Aberdeen and Kuala Lumpur. Established in 1982, Trident provides process planning and safety consulting services to the oil and gas in- dustry. The company describes its service portfolio summarily as “management of operational risks to operating systems, people, the environment, asset revenue and reputation.”



Photo: Statoil

GIANT. Nearly 500 metres tall, “Sea Troll” located off the Norwegian coast is the world’s largest drilling platform.

in waters over 300 m deep far off the Norwegian coast, where it produces gas.

A mobile solution suitable for deepwater that can be de- ployed even further away from the shoreline first appeared in 1977 when a Spanish shipyard built an FPSO vessel for the Shell Castel- lo field. 20 years later, the first FPSO system for liquefied gas was completed. One of the largest FPSO units ever built is “Kizomba A”. Designed to accommodate up to 2.2 million barrels, this behemoth is currently anchored 320 km off the Angolan coast.

which represent a substantial capital investment, are subject to risk management as well. “We also advise our customers on technical equipment they need in order to maintain the production plants and keep them in good operating condi- tion,” says Amin. An effect offshore operators dread is the so-called water hammer. It occurs when a flowing liquid is stopped abruptly by a rapidly closing valve. “Our customers want to understand it, control it, and be assured that their equipment can cope with these dynamic effects.”

Integrated Drilling Equipment

FSO and FPSO units offer many benefits in the current vol- atile situation on the energy markets. Oil prices have been fluctuating wildly in recent months, but will inevitably rise in the long term. Even in remote oil fields and challenging environments, mobile crude oil storage systems can make oil production economically feasible. Perhaps their most important advantage, says FPSO expert Amin, is their flex- ibility. Once an oil field has been exhausted, the oil com- pany can relocate the FPSO system to another field with relative ease. It is this benefit in particular that is causing the number of FSO and FPSO deployments to rise globally. Not only do these vessels offer volume storage, there are also technical innovations adding value to this concept.

The first-ever FDPSO units already left their shipyards. “D” is for “Drilling”: carrying drilling equipment on board, these innovative floaters can operate more or less in- dependently in offshore oil fields. A yard in Singapore is about to deliver one of the world’s first FDPSO ships for de- ployment in an oil field off the West African coast in waters 1,500 m deep, says Amin. Trident has developed a compre-

hensive risk management concept for this project.

  • JI

For further information: Raza Amin, Managing Director Trident Consultants Phone: +60 3 2161 0088, E-Mail: raza.amin@trident-consultants.com

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