The Shell Serrano Flowline and Riser Abandonment Project consisted of the abandonment of a 6x10 pipe-in-pipe (PIP) flowline system initiating with a PIP steel catenary riser (SCR) at the Auger TLP located in the Garden Banks 426 area of the Gulf of Mexico in 2,860 feet of water, and terminating with a pipeline end termination (PLET) located adjacent to existing Serrano subsea wells located in Garden Banks 516.

The project work scope included the removal of the existing flowline jumper from a subsea PLET assembly and the flushing of the entire flowline and riser system back to the Auger TLP. The project work scope also included the removal and transfer of the Serrano PIP SCR from the Auger TLP to a multi-purpose service vessel (MSV), followed by the recovery, wet tow and abandonment of two (2) one-mile segments of the Serrano riser and flowline system using MSV's to a designated abandonment site near the Auger TLP field located in approximately 3,200 feet of water. This project represented an industry first in the use of multiple MSV's in lieu of traditional marine installation and construction vessels to perform flowline and riser removal, transfer, recovery, abandonment and wet tow operations required for in-place flowline abandonment operations as approved by the BOEM/BSEE.


CTI project management and construction personnel were integrated into the Shell Serrano Flowline and Riser Abandonment Project Team to provide engineering and project management support, as well as construction management expertise during the concept selection, planning and execution phases of the project, successfully performing the following functions:

• Management and direct onshore supervision of equipment selection, design, refurbishment, preparation for offshore use and systems integration testing (SIT) of all SCR transfer equipment required for SCR removal and abandonment operations.
• Management and field supervision of all onshore structural fabrication and specialized equipment and rigging procurement and testing activities required to perform riser transfer and abandonment activities on the Auger TLP.
• Engineering, planning, management and coordination of all offshore SCR removal and transfer operations (including SIMOPS coordination), including direct responsibility for the development of detailed equipment mobilization, riser lifting and riser transfer procedures and safe work plans for all activities occurring on the Auger TLP.
• Assist with management, planning and procedure development activities performed by the selected marine installation contractors and vendors required to perform flowline and riser transfer, wet towing and abandonment operations.
• Assist with selection, design, fabrication and testing of all specialized subsea equipment and tooling required for flowline and riser recovery, abandonment, and wet towing operations, including selection and testing of all required subsea flowline and riser cutting, handling and plugging equipment and tooling.
• Direct offshore management, supervision, coordination and interface with Auger TLP Operations personnel required during all SCR removal and abandonment operations conducted on the Auger TLP.