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Received: 3 April 2019 Accepted: 8 June 2019 To improve the drilling efficiency of impregnated diamond drill bit in strong abrasive rock layer, this paper introduces the theory of primary and secondary abrasives into the drill bit design, and explores the drilling efficiency and service life of diamond drill bits with six formulas of primary and secondary abrasives through indoor and field tests. The results show that the drill bits with primary and secondary abrasives had an 85% higher efficiency and a 46% longer service life than the conventional drill bit. In the course of drilling, the matrix of the ordinary drill bit was soon worn out due to the repeated grinding by a large amount of medium and coarse rock powder, losing the ability to hold the diamond in place. Then, the drill bit became less durable or efficient. These defects could be overcome by our diamond drill bit design. If applied to strong abrasive formations, the primary and secondary abrasives of our design can crush the medium and coarse rock powder into finer powder. The fine rock power can be discharged timely and rapidly through the bit end via the drilling fluid.

Design of Diamond Drill Bits with Primary and Secondary Abrasives