A challenging deepwater application required enlarging a 121/4-in. pilot hole to 141/2 in. through hard and abrasive interbedded sands, and the customer needed to complete the job without sacrificing penetration rates or drilling performance. They also needed to drill and ream the section to total depth (TD) in a single run—eliminating the rathole without having to trip out for a second hole-opening assembly. After analyzing offset well data, it was evident that conventional under-reamers using standard polycrystalline diamond compact cutters couldn’t complete this application in one run. This is because traditional reamers/cutting structures often cannot withstand abrasive, highly interbedded formations, resulting in the need for complex bottom hole assemblies and m

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