This paper addresses the first phase (Phase 1) of a JIP formed for the development of emergency repair capability for pipelines and flowlines in water depths in the 1,000-10,000 ft range, in the US Gulf of Mexico. Stress Subsea (SSI) conducted a Failure Mode and Effects Analysis, conducted interviews with suppliers and operators and, included input from the JIP's Steering Committee, to make recommendations for two different repair methods to support the emergency repair of larger diameter pipelines and flowlines, respectively.
For larger diameter pipelines the recommendation is to use two "structural" leak clamps to make spool piece repairs, or use one of the two to clamp a pinhole leak. The use of the same clamp design for either application avoids needing multiple tools. For flowline repair, the recommendation is to cut the flowline on bottom, lift the ends to the surface to add fittings, then lay the flowline ends on bottom to join them with a vertical jumper system containing twin collet connectors. Major pipe damage and pinhole leaks would be repaired the same way.
The JIP consisted of a number of US Gulf of Mexico and International Operators, as well as U.S. Government agencies.
Starting with a collection of operator/participants pipe "dedications", the JIP prepared a Design Basis which served as guidance for various equipment inquiries and requests for quotes. These pipe dedications defined, among other things, size, length, wall thickness, grade and the MAOP of the dedicated pipelines. Interviews where conducted with key deepwater products manufacturers, installation and repair contractors, as well as operators with experience in developing deepwater repair methods.
Throughout the project, the JIP held 5 project meetings, met with international operators which already have developed similar systems, for their views and lessons learned, and met with other industry leaders to get their input and advice. The intent of the interview process was to sum up the most recent knowledge and experience, thus avoiding "reinventing the wheel" [1,2], and allowing for a fast decision making on what would be a low CAPEX, cost effective solution for deepwater pipeline repairs.
Based on information obtained from the MMS database, a Failure Mode and Effects Analysis (FMEA) was prepared to predict what failure modes would be more likely in the deep water environment. The results of the FMEA where used in selecting the candidate repair methods for DW RUPE.
Recommendations contained in this paper are thought to be an up-to-date, comprehensive discussion of the deepwater repair scenarios, and provide cost effective solutions to meet the requirements set forth by the JIP's Steering Committee.
The objectives of the Phase 1 project were as follows:
To identify pipeline and flowline size ranges of participants, including insulated and non-insulated conventional pipe, as well as pipe-in-pipe options, as applicable.
Identify and evaluate the likely pipeline and flowline damage conditions, using the damage categories outlined in the MMS database of Gulf of Mexico pipeline leaks.