PDC DRILL BIT HAVING CUTTING STRUCTURE ADAPTED TO IMPROVE HIGH SPEED DRILLING PERFORMANCE

摘要

A drill bit is disclosed which includes a bit body having a plurality of blades thereon. The blades have a plurality of cutting elements affixed thereon at selected positions. The cutting elements are disposed into at least two groups. A fir st one of the groups has at least 60 percent of the cutting elements therein disposed at a first mean backrake angle. A second group has at least 60 percent of the cutting elements therein disposed at a second mean backrake angle. The second backrake angle is at least about fifteen degrees more than the first backrake angle. A bottom ho le coverage of the cutting elements in the second group is at least about eight y percent.