The story began years ago, when the oil industry realized that efforts to reach new deposits of oil discovered in deeper and deeper water were constrained by the weight of the steel equipment in its offshore drilling rigs.
One area of significant weight limitation was the drilling riser systems—essentially very large tubes that go from the drilling platform to the ocean floor, at distances of approximately 3.6 kilometers (more than two miles). Drilling risers are essential because they contain not only the drill string, but also the drilling fluid that is continually circulated from the bottom of the well back to the drilling platform where it is filtered for reuse. “The steel riser system needed to reach these new depths would sink the ship,” said Peter Mamuzic, director of Global Market Development for Global Hard Alloy Extrusions. “But with a 30–40% weight savings, aluminum makes it much more economical to take existing ships to the deep water where new oil reserves are being found.”
Riser systems are safety-critical engineered structures that facilitate not only the transfer and use of the drill stem and drilling fluid, but also control the subsea blowout preventers, which are critical to the safety and security of the drilling platform and workers. “Creating an aluminum riser requires the technical sophistication of an airplane, only underwater,” said Eric Roegner, president of Global Hard Alloy Extrusions. “Environmentally and production-wise, the riser has to perform without failure,” said Mamuzic.
Unlocking Potential
What are the advantages of aluminum? “It’s all about sustainability, energy and getting further, deeper, faster,” said Roegner. “They can’t go any deeper with steel. But utilize aluminum and all of a sudden you can economically reach untapped reserves.” Beyond aluminum’s obvious performance advantages, it’s also an environmentally friendly and renewable resource that maintains its value far beyond traditional steel materials. Leveraging existing equipment and assets while going to greater depths could save a driller a hundred million dollars over investing in a new drill ship.
Alcoa's riser expertise has roots in Samara, Russia—which boasts the largest extrusion and forging presses in the world. “Generation I” set sail with four ship-sets—reaching depths of about 6,000 feet—successfully put into production in 2001 and 2002.
Alcoa’s expertise came into the picture with our 2005 acquisition of Smara Works from Rusal. “All of Alcoa’s global capabilities are needed to make this work,” said Roegner. The Russian team was joined by the Alcoa Technical Center in Pittsburgh, Pennsylvania, USA, which brought alloy, manufacturing and production technology such as friction stir welding into the solution.
Teams at Alcoa’s U.S. facilities in Lafayette, Indiana and Cleveland, Ohio shared their experience in meeting the exacting standards of the aerospace industry. “Technology, forgings, extrusions—all three need to work together with the customer in an environment where we’re constantly problem-solving, because this is a prototype application that’s never been done before,” said Roegner. The first ship-set of “Generation II” currently is in production, with all forgings and 60% of the extrusions made in Samara. The remaining 40% of extrusions are produced at Lafayette.
A single riser requires approximately 1,110 metric tons of aluminum; a typical ship-set is made of about 150 risers.
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