Study On Structural Design And Rock Breaking Mechanism Of Bionic PDC Cutting

As China’s oil and gas drilling on marching to the deep and complex stratigraphic reservoirs, the drilling tool has confronted great difficulties and trials which come from the increasing complexity of downhole drilling conditions and difficult formations. At present practical drilling operations, PDC bits’ failure was largely attribute to the teeth collapse and broken. Cutting teeth is basic cutting unit of PDC bits and its structural property directly affects the drilling efficiency and PDC drill bit life.This paper applies the bionic principle to conduct the structural design of new bionic PDC cutter. Through systematic and careful research on the soil fauna claw of gryllotalpa and the scales structure of pangolin, then apply the biological principles contained in them to the structural design of new bionic PDC cutter, and eventually has made a shape which can stratified breaking rock and with lower vibration. The new bionic PDC cutter, which changes the way rock breaking and easier to eat into the formation, is different from the traditional cutting teeth in rock breaking mechanism, meanwhile, the stepped structure more conducive to rock stripping. Furthermore, contrastive analysis has been conducted between new bionic PDC cutter and conventional teeth in single-tooth and whole drill by using the finite element method. The results show that the performance of the new bionic PDC cutter is obviously superior to conventional cutting teeth. While carrying out experimental research related to a single rock breaking teeth. The main achievements of the paper:(1) Based on the shape of gryllotalpa’s claw and the structure of pangolin’s scale, a new bionic PDC cutter, which improved methods and improve the stress state compared to the traditional rock-breaking cutting teeth.(2) With classical elasticity and Hertz contact theory, the contact mechanical behavior of the conventional cylindrical cutter has been described, while derived their contact pressure distribution and contact parameter calculation formula. The result has been extended to the bionic teeth, which approximate to the theoretical study.(3) Comparative simulation analysis of different cutting teeth breaking rock show that many of the key indicators of bionic teeth are better than conventional cylindrical cutting teeth (under the same drilling parameters and conditions, the biggest rock breaking torque of bionic PDC bit decreases by about33.3%, while the rate of invasion energy up62.5%), which convincing indicates that the design of biomimetic tooth structure was correct, while evidence of the feasibility of using bionics to design bionic cutting tooth.(4)Single rock breaking experiments has studied on different cutting teeth tooth and results showed that:at the same eat depth, cutting speed and external conditions, the size of cutting force of bionic teeth account for50.94%of the counterpart of conventional cylindrical teeth.