Fishermen know corvina (aka sea bass) as a feisty fighter found along the coasts of the southern Pacific. Foodies know corvina as a tasty ingredient in ceviche, a Peruvian delicacy. For Wison Offshore and Marine and Horton Wison Deepwater employees, Corvina is not a fish; it is the home of their newest design off the coast of northwestern Peru.

The BPZ CX-15 platform, according to Wison, is the world's first buoyant tower drilling and production facility. With a little creative thinking and some tweaking of their deepwater design principles, the team at Horton Wison Deepwater delivered to their client, BPZ Energy, this platform specifically suited for shallower water deployment.

Seen here is an artist’s rendering of the BPZ Energy CX-15 buoyant tower drilling and production facility. (Image courtesy of Horton Wison Deepwater)

"This design really comes into its own in water depths greater than 80 m (260 ft), where the buoyant tower needs much less steel than a conventional fixed jacket," said Chris Harding, vice president of business development for Horton Wison Deepwater. While the BPZ project is outside of this range at a water depth of 54 m (177 ft), the structure fit the bill in regard to Peruvian seismic criteria.

"It is a compliant structure and does need to move with the waves," said Lyle Finn, chief technology officer for Horton Wison Deepwater. "It is this feature that makes it impervious to earthquakes. The earth can shake, but the top part is buoyant, so it stays vertical."

The buoyant tower hull consists of four connected, ring-stiffened cells that measure 8.4 m (28 ft) in diameter and 60.1 m (197 ft) long. The cells surround a central suction pile, bringing the total hull length to 69.9 m (229 ft). The suction pile, similar to a spud can, is what moors the tower into the seabed.

Tower total weight is 2,500 tons, and it supports a three-level drilling and production topsides facility that weighs in at 2,300 tons. The topside is fully equipped to produce 12,200 b/d of oil and 12.8 MMcf/d of gas and inject 3,500 b/d of water, and it also is capable of supporting a drilling rig servicing 24 well slots.

Constructed in 11 months at Wison's fabrication facility in Nantong, China, both were loaded onto the Osprey, a heavy lift transport vessel, before departing for Peru in early August. Installation began shortly after the Osprey arrived in BPZ Energy's Corvina field in Block Z-1, approximately 1.6 km (1 mile) from BPZ's CX-11 platform, in early September.

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