Greater Plutonio - Progressive Subsurface Management in a High Cost, Subsea Environment

Abstract

Greater Plutonio is BP's largest subsea development with an initial plan to drill and complete 43 high tech, high cost, high rate subsea development wells. A relatively low level of classical field appraisal was possible because of high industry costs coupled with the fast pace of the project. Innovative subsurface management has therefore been required to reduce substantial uncertainty during the development phase. Full use has been made of excellent HiRes seismic data. An optimised well order has been crucial to reduce depth uncertainties and facilitate a focused, early data acquisition programme - while incrementally tackling more and more complex drilling and completion challenges. Extensive learnings have been possible from reservoir interference data resulting from rig-based production and injection tests. The application of some specific technologies has been key to the success of the project: widespread use of a Subsea Acoustic Monitoring System to interrogate downhole pressure data from multiple offset wells prior to subsea system installation; 100% reliance on Subsea MultiPhase Flowmeters during initial ramp-up and subsequent operations; Extensive use of remote sensing technologies relayed real time to office desktops and fully integrated with well models to facilitate immediate well and reservoir management. This has enabled significant reservoir learning and therefore reservoir management not only in the early ramp-up phase but actually before field start-up, which was achieved on 1st October 2007. In turn this has allowed the on-going development drilling order to be honed to maximise early production and injection. The successful subsurface and wells management of Greater Plutonio has been demonstrated by the delivery of sufficient production potential to allow field rates of 200mbd in January 2008 (after just over 3 months of operations) and over 300mmscf/d of injection potential at the time of first gas injection less than 2 months after first oil. In addition, by early 2008 water injection had reached 120mbwd into 4 wells, with potential for a further 40mbwd already completed and tested. Establishment of full voidage replacement in 2008 to allow sustainable plateau production is ahead of plan. The enhanced reservoir understanding from the pre-first oil and ramp-up data has reduced subsurface uncertainties while the Greater Plutonio development has progressed and will play a crucial part in increasing ultimate field recovery.