Houston, TX – Cal Dive International’s (CDI) Multi-Service Vessel (MSV), UNCLE JOHN has completed its first well intervention project undergoing a derrick retrofit in February. Combining an innovative approach with technologically advanced equipment, this successful project confirmed the viability of CDI’s new service capability to operators of subsea wells. The project was the first of its nature involving wireline intervention from a non-drilling vessel on dynamic positioning in the Gulf of Mexico. The DP semi-submersible UNCLE JOHN was outfitted with support equipment from Schlumberger Oilfield Services, an alliance partner of CDI. Schlumberger supplied surface control and testing equipment for through-tubing wellbore intervention. Also providing equipment were Vetco, Halliburton and Kvaerner FSSL.
The task included repairs to a velocity valve and a chemical injection valve under the supervision of representatives from Shell deepwater Development, Inc.’s drilling and subsea systems group. The Minerals Management Service was also on board.
The UNCLE JOHN mobilized under its own power from Galveston, Texas to Viosca Knoll Block 783, where the water depth is 1,494 feet. After ballasting down to its operating draft of 50 feet below mean sea level and engaging the Cegelic 902 DP system to coordinate the eight thrusters for maintaining precise positioning over the sub sea well, the UNCLE JOHN was ready to commence operations. Safety equipment and redundant systems were put in place for maintaining a precise position over the well and safeguards were developed to ensure the pressure containment system functioned properly. The riser tensioning system was tested several times and Emergency Shut Down – Emergency Disconnect – Gas Detection Systems were extensively tested prior to departure and again on site.
Working without guide wires through a five inch riser and work over control system, the UNCLE JOHN team made 11 successful wireline runs into the well and in the end re-established production to the nearby platform. Total time on site was six days, confirming the cost effectiveness of this technical approach to well intervention.
Houston based Cal Dive International, Inc. is a leading subsea service contractor and operates the largest fleet of dynamically positioned diving support and subsea construction vessels in the gulf of Mexico.