Rotary cutting tests and rock-breaking characteristics of triple-ridged PDC cutters in tight hard sandstones from Xujiahe Formation in Sichuan Basin in China

The Upper Triassic, particularly the Xujiahe Formation in the Sichuan Basin, exhibits significant exploration potential. However, reservoir characteristics such as low permeability, deep burial, and strong heterogeneity, limit the rock-breaking efficiency and service life of PDC bits. This study conducted experiments on the penetration and cutting of tight hard sandstone under drilling motion conditions, and compared the characteristics of triple-ridged PDC cutters (TRC) and planar PDC cutters (PLC) penetrating and cutting tight hard sandstone. Research results indicate that the optimal rock penetration effect is attained when the penetration angle of the PLC is 30° and that of the TRC is 25°. Under drilling motion conditions, the TRC exhibit superior stability during rock fragmentation and induce greater damage to the rock bottom. As the penetration velocity rises while the rotational speed drops, the extent of rock fragmentation diminishes; however, the fragmentation efficiency improves. Under these circumstances, the rock-breaking volume increases, and the mechanical specific energy (MSE) decreases. In the process of drilling in highly abrasive sandstone formations, it is advisable to adopt high bit weight and medium-low rotational speed in engineering parameters. This research offers theoretical underpinnings for the design of drill bits and the selection of engineering parameters within highly abrasive formations.