The improved rock breaking efficiency of an annular-groove PDC bit

To solve a major problem faced by drilling technicians, that of how to improve rock breaking efficiency in complex strata, this paper introduces a polycrystalline diamond compact (PDC) drill bit with a special structure. Static-pressure breaking tests show that the breaking work ratio of a single tooth on a ridge is much smaller than that on flat rock samples, and the effect of ridge height on breaking work ratio is greater than that of ridge width. Single-tooth scrape tests show that the tangential force, axial force, and breaking work ratio of PDC teeth when scraping on a ridge are greatly reduced compared with flat rock samples, and the ridge width has a greater influence on the breaking work ratio than ridge height. A test bit with a diameter of 215.9 mm and the possibility of zero, one, or two annular grooves is designed and manufactured. Compared with the conventional, full-coverage PDC bit, the specific energy of the double-groove bit is reduced by 26.9%. The annular-groove PDC bits achieve large-scale cuttings when breaking the ridge created by the bit, and the rock breaking efficiency is greatly improved. At the same time, the raised ridges of the bottomhole increase the stability of the drill bit, providing a feasible solution for rock breaking when drilling complex strata.