Evolution of Polycrystalline Diamond Compact Bit Designs for Rocky Mountain Drilling

Abstract

The Rocky Mountain region of the U.S. has proved to be a good area for polycrystalline diamond compact (PDC) bits in selected formations. Lower costs per foot as a result of higher penetration rates and longer bit lives have been realized in many applications. PDC bits are used routinely in Wyoming in the Green River and Powder River basins. Simply using a PDC bit in these areas does not necessarily ensure an economical run. Care must be taken in choosing the correct bit design for each application to obtain the lowest cost per foot. Since the first PDC bit run, there has been an evolution of designs to enhance penetration rates, and thus to lower drilling cost per foot. This evolution has included changes in bit profile, cutter density, cutter exposure, cutter side rake, and cutter shape. When optimally combined, these features have increased penetration rates by well over 100% in many formations.