Pengbo Huo

During drilling in complex formations, the sliding bearings of roller cone bits are continuously subjected to low-speed, heavy-load, and boundary lubrication conditions, under which adhesive failure readily occurs, severely limiting drilling efficiency. To enhance their wear resistance, a bionic texture inspired by shark denticles was designed and compared with conventional rectangular and circular textures. An equivalent pin–disk contact model was established based on Hertzian contact theory, and tribological experiments were conducted under typical formation conditions using a friction and wear testing machine. The friction coefficient, friction torque, and wear volume of different textures were measured under both lubricated and dry contact conditions, and the underlying mechanisms were elucidated through three-dimensional surface morphology analysis. The results show that the shark denticle-inspired texture reduced the friction coefficient and wear volume by 33.3% and 35%, respectively, under lubrication, while suppressing debris intrusion at the frictional interface under dry contact, thereby providing a degree of surface protection. This study offers theoretical guidance and experimental evidence for advancing the engineering application of bionic tribology in the petroleum industry.

In oil and gas field development, the highly mineralized formation water environment often leads to casing corrosion, significantly reducing its collapse strength and service life. To investigate the corrosion characteristics and mechanical degradation of casings in formation water, this study combines high-temperature high-pressure (HTHP) corrosion experiments with finite element analysis to examine the influence of corrosion pit geometry and volume loss on casing collapse strength. Based on experimental data and simulation results, the safe service life of casing under various conditions is also predicted. The results show that greater material loss due to corrosion leads to lower collapse strength. Under the same volume loss, cylindrical pits cause the most severe reduction in collapse strength, while semi-ellipsoidal pits result in the least degradation. Elevated temperature and pressure significantly accelerate corrosion and further reduce mechanical performance. Under service conditions of 20 MPa–80 °C, 11 MPa–50 °C, and 2 MPa–20 °C, the predicted safe service life of the casing is 4.84, 7.57, and 11.61 years, respectively. The approach proposed in this study provides a reference for the evaluation of collapse resistance and service life prediction of casings exposed to formation water environments.