The innovative cutting mechanism of multi-dimensional teeth presents a groundbreaking approach to drill bit design, particularly optimizing drilling efficiency in challenging geological formations such as interlayers and gravel-rich layers within the Changqing Oilfield. Nevertheless, compared to conventional flat-tooth PDC drill bits, several aspects of the cutting mechanism and design parameters for multi-dimensional teeth require further elucidation. This article employs a linear cutting finite element model to establish cutting models for traditional flat teeth and two distinct types of multi-dimensional teeth, designated as Ridge and Benz. It systematically investigates the influence of varying cutting parameters on the effectiveness of rock-crushing within the multi-dimensional tooth-cutting mechanism. This study conducts laboratory-based single-tooth rock-crushing experiments to validate the numerical simulation results. Furthermore, applying principles derived from soil plastic mechanics contrasts the stress states experienced by rocks during the rock-crushing process between multi-dimensional teeth and conventional flat teeth, shedding light on the rock-crushing mechanism employed by multi-dimensional teeth. This research categorizes PDC cutting teeth on the drill bit into two groups: those near the center and those near the outer shoulder. A linear cutting model for teeth positioned near the outer shoulder is developed to analyze the impacts of different rake angles, side clearance angles, and welding errors on the tooth helix angle and the rock-crushing efficiency of the Benz tooth. This comprehensive study is a valuable reference for tailored drill bit design and holds potential for publication in a prestigious scientific journal.

The increased overheating hazards of degraded batteries have become the predominant cause of thermal safety issues in energy storage devices. To address this issue, dynamic thermal management strategies are urgently needed for all-lifespan safe operations, especially under the growing demands for ultra-fast charging. This study proposes a multi-objective optimization framework of immersion cooling strategy for all-lifespan ultra-fast charging, considering the thermal control and energy cost. First, all-lifespan fast charging evolution mechanisms are revealed. Results indicate that degraded batteries generate more heat due to more significant side reactions. Module maximum temperature (Tmax) and temperature standard deviation (TSD) rise to 164.35℃ and 5.5 K under 4C charging (60% SOH), inducing nonuniform temperature distribution, and degradation. Moreover, module temperature can also be controlled within a desirable level (Tmax: 43.7℃, TSD: 2.3 K) under the most challenging operation (4C charging, 60% SOH), through immersion cooling. Furthermore, the coolant flow rate thresholds are optimized for all-lifespan cooling control under the harshest conditions, evaluated from temperature control and energy cost perspectives. Tmax, TSD, and energy cost (W) are decreased below 33℃, 6 K, and 180 kJ, respectively, with the threshold q1. This study guides all-lifespan thermal safety management for future energy storage devices.

This paper develops a finite element analysis model to investigate the seepage characteristics of cement sheaths, considering the flow properties of their porous medium. The model’s applicability under various conditions was evaluated through grid sensitivity tests and model validation, indicating that it effectively captures the seepage behavior of cement sheaths with a reasonable degree of reliability. Key parameters, including cement sheath length, permeability, gap structure, pressure differential, and fluid properties, were analyzed using finite element methods to determine their impact on seepage flow. The findings reveal that crack width, permeability, and cement sheath length significantly influence seepage flow in both liquid and gas media. These insights enhance the understanding and prediction of cement sheath seepage characteristics under diverse conditions.

In order to improve the cuttings transport ability and well hole purification effect of horizontal shale gas wells in the Sichuan and Chongqing area, a new type of aluminum alloy drill pipe is put forward, and the floatability is validated by theoretical analysis and actual parameter calculation. According to the cuttings migration mechanism, the cuttings cleaning simulation model of the new aluminum alloy drill pipe and the traditional steel drill pipe was established by Fluent, and the hexahedral mesh is used to divide the model. Thus, the mesh independence and convergence of the two models are verified. Then, the simulation model is verified by comparing the calculation results of the two simulation models with the experimental data of the indoor cuttings migration device. Finally, the rock-cleaning ability of the two drill pipes is analyzed under the conditions of changing the cuttings particle size, well inclination angle, displacement, and mechanical speed. Compared with the traditional steel drill pipe, the new aluminum alloy drill pipe can improve the borehole purification capacity by 13% on average. This research result is of great significance in reducing the quality of cuttings in the annulus and improving the borehole purification effect.

Through numerical simulation, this study investigates the flow field characteristics of the variable diameter stabilizer in drilling tools under various conditions. It analyzes the influence of different flow rates and speeds on axial velocity and pressure distribution. The results indicate that more significant flow rates correspond to higher average axial velocities across sections, facilitating the transport of drilling fluid and cuttings. Increasing rotational speed leads to greater pressure differences between adjacent sections, consequently elevating the overall pressure drop of the tool, which, to some extent, aids in transporting drilling fluid with cuttings. During rotation, the vortex zone on the backside of the stabilizer creates a hovering and accumulation of cuttings, causing mud agglomeration, thereby affecting tool performance. During structural optimization of the tool, priority should be given to a transitional design of the outlet area in the functional core zone, aiming to alleviate the impact of abrupt structural expansions on cuttings transport.

The built-in pulse impactor used in oil and gas drilling often suffers from erosion issues, which reduce mechanical drilling speed and significantly shorten the drill bit lifespan. To address this, this study employs computational fluid dynamics (CFD) with the discrete phase model (DPM) and DPM erosion model, combined with erosion theory, to simulate the erosion process. The computational domain includes the rotating body, housing, and internal flow channels of the impactor, with key structural parameters: external diameter 120 mm, internal flow height 23 mm, and flow channel angle 30°. Boundary conditions are set as follows: inlet velocity of drilling fluid ranges from 27.558 to 32 m/s, solid particle diameter varies from 0.074 to 0.11 mm, and particle mass flow rate (concentration) is 0.2–0.6 kg/s. The study analyzes erosion lifespan of different materials and identifies influencing factors. Results show that under high-pressure drilling fluid conditions, solid-phase particles cause significantly greater erosion than the liquid phase. Particle distribution is uneven, leading to accumulation in the rotating body, erosion damage intensifies over time, concentrating primarily at the flow channel outlet. CFD simulations indicate that 40CrMo has the longest erosion lifespan (525.47 h), outperforming 45 steel and Q235A. Regarding influencing factors: increasing fluid velocity (especially 30–32 m/s) and particle concentration (0.2–0.5 kg/s) significantly raises the erosion rate; larger particle diameters reduce the erosion rate, with the decreasing trend slowing when diameter exceeds 0.09 mm. The erosion rate is maximum at impact angle 30 °C. This study provides insights for reducing erosion and extending the service life of built-in pulse impactors.