Experimental study on the rock-breaking mechanism of disc-like hybrid bit

In order to solve the problems of low rate of penetration (ROP) and short service life of the bit drilling in hard formation, and further improve the performance of conventional hybrid bit, a hybrid bit, disc-like hybrid bit (DLHB) is put forward. The hybrid bit has the advantages of conventional Polycrystalline Diamond Compact (PDC) bit and disc-like roller bit. With analysis on the structural characteristics and rock-breaking mechanism of DLHB, comparison experiments on DLHB and conventional hybrid bit are conducted. The results show that prefracturing of the disc inserts is quite significant. The circumferential coverage of the grooved craters produced by disc insert-rows is 40% higher than conventional teeth-rows, and the dynamic load factor is much lower. Besides, ROP of DLHB is 30% higher and weight on bit (WOB) fluctuation is 15%-25% lower than the conventional one in hard formation. DLHB can make the PDC cutters and bearings more durable and it has longer service life compared with conventional hybrid bit.