Search Results (3)

In order to study the breaking mechanism of rock of high-speed PDC drill bits, improve the cutting efficiency of cutting teeth, and reduce the wear of cutting teeth, the rock-breaking process of PDC cutting teeth is simulated based on mechanical theory knowledge and experiments in this paper. And the influence of changes in PDC tooth rake angle, cutting depth, and diameter of the cutting tooth was studied by changing the different structural and cutting parameters of the cutting teeth, as well as the changes in cutting force, frictional resistance stress, and contact pressure on PDC teeth during the cutting process. The simulated results show that the total energy of the system increases, and the total energy of the system is the largest when cutting at 45°, which coincides with the maximum contact pressure on the teeth at this time. At the same time, it also shows that the impact resistance of PDC teeth is the strongest when chamfered at 45°. The contact area is also smaller, so the cutting is more conducive to the cutting tooth eating into the formation and prolonging the service life of the cutting tooth when the tooth rake angle is 20°. The experimental results showed that, in the actual design of PDC drill bits, an appropriate smaller side angle is not only beneficial for chip removal, but also helps to prevent lateral vibration and does not have a significant impact on cutting load. Finally, obtaining the relationship curve between structural parameters and rock properties is of great significance for guiding the design of PDC drill bits, understanding the intrinsic mechanism of rock fragmentation, and revealing the macroscopic nonlinear mechanical behavior of rocks. Full article

Unconventional tight oil and gas resources, including shale oil and gas, have become the main focus for increasing reserves and production. The safe and efficient development of unconventional oil and gas is a crucial demand for the energy development strategy. Deep tight oil and gas resource development generally adopts horizontal well drilling methods. During drilling, especially in long horizontal sections, the high temperature frequently causes failures of downhole drilling tools and rotary steering tools. The temperature rises sharply during rock breaking with the drill bit. Existing wellbore heat transfer models do not fully consider the impact of heat generated by the drill bit on the wellbore temperature field. This paper aims to experimentally study the temperature rise law of the cutting tooth of the bottom polycrystalline diamond compact (PDC) bit during rock breaking. A set of evaluation devices was developed to study the temperature field distribution characteristics at the bottom of the PDC bit during rock breaking under different experimental conditions. The results indicate that the flow rate of drilling fluid, bit rotation speed, and weight on bit (WOB) significantly affect the distribution of the temperature field at the well bottom. This experimental research on the temperature field distribution characteristics at the bottom of the PDC bit during rock breaking helps reveal the heat transfer characteristics of the long horizontal section wellbore, guide the optimization of drilling parameters, and develop temperature control methods. It is of great significance for the advancement of efficient development technologies for unconventional resources in long horizontal wells. Full article

Drill bits are the main rock-breaking tools in the petroleum and gas industry. Their performance directly affects the quality, efficiency, and cost of drilling. Drill bit manufacturing mainly employs traditional mold forming processes such as milling molding and press molding, which have low production efficiency and long processing cycles and are not conducive to rapid responses to field requirements. Inadequate production accuracy makes it difficult to produce drill bits with complex structures. Three-dimensional (3D) printing technology has fast molding speeds and high molding accuracy. In this paper, 3D printing was applied for the first time to the manufacture of molds for carcass polycrystalline diamond compact (PDC) drill bits and PDC–cone hybrid drill bits. In comparison with forging and milling molding, 3D printing improved production efficiency. The manufactured molds had higher machining accuracy. The ability of 3D printing to make molds with complex surfaces enables the development of drill bits with complex structures. A field experiment was conducted on a PDC drill bit produced by 3D printing, which had a higher rate of penetration and was more efficient in breaking rocks than bits manufactured by traditional processes. The ROP of the drill bit increased by 20.1–25.8%, and the drilling depth increased by 7.7–29.5%. It is therefore feasible to apply 3D printing to the manufacture of petroleum drill bits. Full article