Abstract
Subsea7 have designed, fabricated, and installed Bundles (towed pipeline production systems) for over 33 years, with 69 installed to date.
Over the previous 3 decades operators choice of Bundles as a field development option has been steady but intermittent. However over recent years Bundles have been embraced by field developers as a technically and commercially attractive solution to allow difficult fields to be developed, they are now being proposed by operators and design houses at concept selection phase.
Subsea7 is currently experiencing the busiest period of Bundle design/installation activity ever; a record 8 bundles installed during 2011/2012 and further 8 confirmed installations by the Q2 of 2015. A number of the installed or currently in-design Bundles are firsts for Subsea7.
The paper will discuss the benefits of Bundle technology for rejuvenating and extending existing facilities or new developments. A number of case studies to demonstrate the technical and commercial advantages will be discussed;
Apache Bacchus – Active Heating of Production Fluid using produced water,
BP Andrew – Longest tie-back utilising Bundles, 4 bundles connected in series totalling 27.8km,
COP Jasmine – Highest Temperature Bundle 155°C (to PD8010),
Total West Franklin – Highest Design Temperature 160°C (to DNV) & Largest Diameter Carrier Pipe,
BG Knarr – Deepest Water Depth 410m, and integrated flow assurance design,
Shell FRAM – First Bundle with two midline structures.
The technical benefits driving the increased interest in Bundle Technology for field development will be discussed;
Highly efficient insulation systems, heated bundles utilising Hot-Water or Electrical Trace-Heating,
Design/construction method allows full system integration testing onshore allowing fast hook up and commissioning offshore, low stress installation method by CDTM (Controlled Depth Tow Method) minimizes stress and fatigue on internal flowlines,
Design of bundle cross-section/system allows expansion at both ends, reducing build-up of axial forces, reducing the need for intermediate expansion spools, and allowing efficient design for HP/HT field developments,
Eliminate requirement for specialised installation vessels (Reel-lay, S-Lay, J-Lay, and Heavy Lift) by utilising readily available vessels, and incorporating subsea structures within the towed Bundle System.
