Abstract
Deepwater drilling needs improved efficincy. Since well delivery cost is a major component of deepwater projects, a 20% reduction in well delivery cost may pull deepwater projects back over the economic threshold. However, sustainability requires looking beyond market cycle price consessions and focus on longer term technology and innovation to drive down the well duration and cost. Accordingly, the industry needs to apply engineered soultions to increase operational efficiency and safety as compared to existing 6th Gen drillship designs.
This paper introduces a next generation drillship design concept, featuring a factory-like approach to well construction, grounded with input from operators and third-party service providers. Capitalizing on Lean methodologies, the design combines improved safety with automation and robotics to reduce bottlenecks and minimize controllable flat time for the entire well life cycle with a reduction in well duration and cost by 15 to 30%.
The author examines the distinctive vessel layout including a large flat and un-obstructed work deck, a high variable load capacity of 27,500 short ton (ST), and increased personnel on board capacity to improve the off-line transition from the drilling to completion phases. In addition, the reorganized drill floor replaces the standard derrick and substructure with a Dual Multi-purpose Tower (DMPT), employing robotic pipe manipulators capable of handling 180-ft stands. To meet future well design requirements, the hoisting system is engineered for at least a 1,500 ST static hook load at the elevators. Further, independent mud and brine systems with 11,000-bbl and 17,000-bbl capacities, respectively, with off-line tank and suction line cleaning, improve well displacement safety and efficiency. Moreover, a unique power distribution network improves both thruster availability and also allows maintenance while operating efficiently in an open buss configuration, thereby stretching the dynamic positioning (DP) operating envelope.
The target of this efficiency and safety-centric initiative is to reduce the operator's well cost and allowing future optimization of 40,000-ft-plus well designs in 13,200-ft water depth.
