Cal Dive International (CDI) recently completed the deepest riser installation in the Gulf of Mexico on Amerada Hess Baldpate compliant tower in Garden Banks block 260.
CDI installed a 16-inch oil riser and 12-inch gas riser in 1,650 feet of water on the 1,900-foot compliant tower project. The tower is the tallest freestanding structure in the world. This was the first time that risers of this size were installed at such depths in the Gulf while utilizing a dynamically positioned vessel as the workstation.
CDI utilized Coflexip Stena Offshores dynamically positioned diving support vessel (DPDSV) Constructor. For the installation, CDI mounted a 250-ton winch amid ship with a 2-inch anchor fairlead on the center of the stern to lift the end of each pipeline off the bottom with the aid of a CDI remotely operated vehicle (ROV).
A joint effort between Amerada Hess, CDI and other engineering firms developed a customized rigging system that was mounted on the compliant tower to transfer the risers from the DSV-mounted winch to the platform-based rigging. CDI used saturation divers and an ROV to secure the risers in clamps at depths of 360 feet and 290 feet.
CDI deployed five vessels in support of the deepwater installation and was responsible for all subsea tie-ins, pigging, testing and commissioning of the pipelines as well as the installation of a future side tap in 750 feet of the 16-inch oil line.
CDI is a leading provider of innovative offshore construction, maintenance and decommissioning services to the Gulf of Mexico oil and gas industry.