Importance

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Abstract

A rotary drill bit comprises a bit body having a shank for connection to a drill string, a plurality of cutter assemblies mounted on the bit body, and a passage in the bit body for supplying drilling fluid to the surface of the bit. Certain cutter assemblies on the bit body are adapted to exhibit a volume factor which is significantly greater than the volume factor of other cutter assemblies on the bit body, with increase of rate of penetration, and at least the majority of said cutter assemblies of higher volume factor are better adapted for cutting softer formations than at least the majority of said other cutter assemblies. The bit therefore tends to act as a 'heavy set' drill bit at lower rates of penetration in hard formations, and as a 'light set' drill bit at higher rates of penetration in softer formations, and therefore tends to drill each formation more efficiently.

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First Claim