NEW ORLEANS – Lessons learned from the Cascade/Chinook deepwater Gulf of Mexico development range from planning to polyester, according to César Palagi, Walker Ridge Asset Manager, Petrobras Americas.
Speaking at the 2011 Deep Offshore Technology Conference, Palagi reviewed the current status of the project and pointed out some of the technological advances that resulted. Cascade/Chinook has applied a number of technologies new to the Gulf of Mexico, Palagi said, and that made the biggest difference in the project.
Because of the project development scheme, his first message was to “work with the authorities from minus day one.” While Petrobras had experience applying many of the techniques used at Cascade/Chinook, many of them required federal approval before implementation. However, because they were new to the GoM, there were no fixed regulations to follow and approvals required a back-and-forth between Petrobras and the agencies involved.
Among the approaches new to the Gulf were the following:
• Polyester moorings. The requirement for a disconnectable turret in case of a hurricane was new to Petrobras. The water depth of 8,250 ft made traditional moorings too heavy, bringing the polyester ropes into play, and accounting for stretch needs to be studied, Palagi said.
• Timing of equipment delivery prompted some novel approaches, too. The FPSO was late arriving on location and the buoy and umbilicals were installed ahead. That meant a first of subsea pull-in of the umbilicals to the buoy rather than to the FPSO as would have been the usual.
• The free-standing riser was a first for the GoM, too, and the way those are engineered will be changed in the future based on the experience at Cascade/Chinook.
• Subsea boosting was selected because of the expenses involved with workovers in that water depth. Palagi said the cost could reach $50 million per well and that meant an alternative had to be used.
• Planning for simultaneous operations in such a complex scenario requires much more attention than usual.
On the positive side, Palagi said that “Cascade and Chinook will pave the way for future Lower Tertiary play developments.”