OTC, May 2009
Authors: Roger van Noort, SPE; Rob Murray, James Wise, Shell; Mark Williamson, Bob Wilde, John Riggs, InterMoor.
This paper presents the requirements that led to the successful implementation of a subsea hydraulic hammer for installation of conductors offshore Brazil.
The Parque das Conchas development required conductors both for wells and for the two Artificial Lift Manifolds (ALM). For the 36 inch well conductors it was important that the conductors were installed off the rig critical path and for the 48 inch ALM conductors the critical issue was the accuracy of the conductor height for subsequent manifold placement. The solution was to install the respective conductors using a subsea hammer deployed from an Anchor Handling Vessel (AHV).
The ALM templates were transported offshore vertically on the AHV’s A-frame, submerged and rotated to a horizontal position, and deployed to the seafloor. Once the templates were correctly positioned, the well and ALM conductors were transported offshore on a specially outfitted barge. The conductors were launched from the barge while connected by a line to the anchor handler. Then they were lowered and allowed to self-penetrate into the seabed.
Once all the conductors were installed, they were hammered to depth using a subsea hydraulic hammer. Both ALM templates were placed accurately in position within 1.5 deg heading and 0.5 m in the horizontal plane and all conductors were successfully installed within verticality and height tolerances.
The campaign included many industry firsts, in water depths ranging between 1650 and 1920m in relatively harsh met-ocean conditions. The industry firsts include:
• Vertical template transportation/insertion through water plane followed by horizontal lowering from AHV
• Deepwater hydraulic hammer spread deployed and operated from AHV
• A new depth record (1920 m water depth) for deepwater hammering.
With the installations in Brazil the operating envelope of deepwater conductor installation with a hydraulic hammer has been significantly increased and provides a viable alternative to conductor installations with a deepwater drilling rig.