A drilling technique that is increasingly being used for performance drilling purposes is Managed Pressure Drilling (MPD). MPD is typically considered a tool to mitigate drilling hazards, and reduce the resulting non-productive time due to encountering lost circulation zones, tight pore pressure/fracture gradient margins, and high pressure, low volume nuisance gas zones. MPD can also be applied as a tool to increase rates of penetration (ROP) in applications where techniques such as air drilling and underbalanced drilling may be unsuitable due to limitations such as borehole stability, water flows, coal seams, or environmental concerns such as flaring gas.

The subject well for this case study was drilled in the Bullmoose area of North Eastern British Columbia, by Shell Canada. Experience from numerous operators working in this area identified the Nikanassin as a very hard, slow drilling formation, which negatively impacts the drilling time and cost curves. The Nikanassin is a hard and abrasive formation, and ranges from 1000 to 1800m in thickness. Also, in certain instances, elevated mud weights are required to deal with high-pressure nuisance gas and/or water flows. This further impedes drilling performance.

In the offset wells that were examined, various mud systems and bits were used, resulting in average ROP's ranging from 1.4 to 2.4m/hr. The implementation of an MPD program allowed for the use of an unweighted flocculated water fluid system, which increased the average ROP to 4.0 m/hr. When compared against low fluid loss mud systems, such as invert, the improvement in ROP was notable, and resulted in considerable time and cost savings.

As with any advanced drilling technique, successful application of MPD technology requires a detailed understanding of the potential benefits as well as limitations.

This paper summarizes the process that was used to identify, plan, and implement MPD as a technology to increase ROP. Lessons learned while planning and executing the MPD operation are discussed, as well as enhancements that are being considered for future applications of MPD in the Bullmoose area.

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