Cal Dive Riser System Deployed in Decommissioning Project

Well Ops, Inc., a subsidiary of Cal Dive International, Inc., announced the successful first application of the company's purpose-built, open water intervention riser system. Cal Dive's well intervention vessel, the Q4000, deployed the system in 1,042 feet of water, where it was latched to a horizontal Cameron tree. The system includes a control umbilical, 2-inch annular line, 7 3/8-inch flowhead and swivel. The lower riser package design allows for sequential activation of the well control and emergency disconnect function while the swivel permits the dynamically positioned Q4000 to change headings during in-well operations.

The riser system was integral to a successful well decommissioning operation conducted for a major client in the Gulf of Mexico. The system remained at depth during through-tubing zonal and annulus abandonment operations. The tree was recovered with the system once the well had been safely plugged. The 7 3/8-inch through-bore system enabled all of the pressure control plugs to be retrieved safely and efficiently while the flexible annulus line maintained circulation throughout cementing operations.

The Well Ops flagship vessel, the Q4000, conveyed the riser system using 6 5/8-inch riser pipe. All other intervention riser systems now available on a rental basis in the Gulf of Mexico have a through-bore of 4 inches or less. That size limit effectively prevents access to horizontal trees, which typically have plugs measuring 4 1/2 inches or greater. Well Ops' commitment to this specialized equipment and vessel provides an array of options for clients to achieve significant cost savings in subsea intervention and well decommissioning operations.