Experimental Study on the Lab Test of Annular-Grooved Polycrystalline Diamond Compact Bit

Abstract

In order to study the rock breaking efficiency of the annular-grooved PDC bit, a test bit with adjustable diameter of 241.3 mm was designed and manufactured. The test bit was used for bench test with adjustable parameters such as width, height, number and radial position of annular groove in two rock samples of sandstone and granite. The results show that compared with conventional PDC bit, the rock-breaking mechanical specific energy (MSE) of the annular-grooved PDC bit is reduced by 33%, and the more the number of the annular groove is, the smaller the rock-breaking mechanical specific energy is and the faster the mechanical bit is; The annular groove is disposed outside and in the core of the bit. The smaller the rock-breaking mechanical specific energy of the bit is, the faster the mechanical drilling speed is; In the sandstone and granite samples, there is an optimal annular groove size (height and width), and the bit’s mechanical drilling speed has been increased. Among them, the speed increase is the most obvious in the sandstone, and the mechanical bit is increased by 27% to 160%. The rock mechanical specific energy is reduced, indicating that annular-grooved PDC bit is suitable for both soft and hard lithology, and has a speed-up effect on both types of strata.