Re-development drilling at Shell’s Ram Powell prospect in the Gulf of Mexico targets profitable delivery of remaining hydrocarbons present in lower-volume reservoir pockets. Marginal economics put a strong focus on efficient operations, which are complicated by the technical challenges posed by severely depleted reservoirs (up to 6,000 psi differential pressure) that can only be accessed by drilling extended reach (ERD) wells. Specific challenges that had to be overcome in drilling recent Ram Powell wells include negotiating very narrow drilling margins, preventing major non-productive time associated with well control, lost circulation and stuck pipe events, and drilling the wells at optimum efficiency and favorable economics. This paper discusses the integrated operational plan that the Ram Powell team employed to successfully drill four recent ERD development wells and two slim hole sidetracks through substantial depletion while becoming one of the best- performing offshore operational teams in Shell. Specific tactics discussed include: (1) a fit-for-purpose hole cleaning program for ERD and depleted wells; (2) a mud weight and ECD strategy that exploits the naturally existing stress cage; (3) an effective method to raise fracture propagation pressures in case of losses in induced or natural fractures; (4) the use of flat-rheology synthetic-based mud to minimize barite sag and reduce ECDs; (5) addressing the underestimated effects of temperature, annular pressure fluctuations and exposure time on wellbore stability and lost circulation; (6) contingencies to deal with well control issues during a catastrophic loss; (7) dealing with detrimental vibrations during depleted sand drilling.
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