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Dynamic hydraulics modeling and multi-phase kick tolerance analysis on a narrow margin deepwater well in offshore Malaysia created realistic and accurate pressure predictions, enabling the well to be drilled safely and efficiently and ultimately gave access to additional potential reserves. If conventional modelling alone had been used in the well design, then the well would have been deemed un-drillable, with a predicted drilling window as low as 0.46 ppg. Dynamic modeling delivered greater insight into the pressure and temperature transients throughout the drilling, tripping, casing, cementing and well killing operations. The well planning process took into account pore pressure and wellbore stability predictions and the drilling risks identified in offset wells, but also included dynamic ECD/ESD simulations and dynamic multiphase kick tolerance modeling to evaluate the drill-ability of each casing seat design. The operational effects of frictional pressure losses through the RCD and MPD lines, mud properties, booster pump rate management and detailed mud rollover plan were also included. The transient analysis increased the drillers’ confidence in accessing this challenging horizon safely. The dynamic simulations included many drilling input parameters, such as pump rates, mud weight schedules, tripping rates, well control events and cementing schedules, giving greater insight to the operations team, allowing for smoother well construction activities. Operational decision trees and a pore pressure communication protocol established during the well planning stage helped optimize overall performance. During execution of the drilling operations, the pre-drill models were continually updated based on the actual parameters observed, including real time pore pressures, leak off tests and mud temperatures, to ensure wellbore pressures were well managed, thereby minimizing drilling risks related to wellbore stability and pore pressure. Pre-section modeling and real-time monitoring assisted the operations team in decision making, saving costs and allowing the well to reach maximum drillable depth safely. Overall two casing strings were eliminated, which translated to 21% drilling cost reduction and 9.5 days saving. This narrow margin well pushed the well engineers to look beyond the traditional methods of well planning using steady state modeling, which is inherrantly conservative. Through the use of dynamic modeling, replicating the real drilling operations more accurately, increased operational margins were identified, allowing the well to be drilled safely and efficiently. |
