Wang Xinrui, Zhang Hui, Dong Zhuoxin, Li Jun, Qin Cheng, Yang Boyuan, Zhou Yuting
Petroleum College, China University of Petroleum at Karamay, Karamay, 634000, China.
Petroleum Engineering College, China University of Petroleum (Beijing), 102249, Beijing, China.
Sci Rep. 2024 Oct 15;14(1):24159. doi: 10.1038/s41598-024-76293-1.
As oil production increasingly transitions from shallow to deep formation, the need for efficient PDC cutters to drill through deep hard rock becomes paramount. Currently, there is a lack of effective methods for optimizing cutter shapes and their cutting parameters. This study addresses this gap by developing a rock-breaking mechanism model for PDC cutters and proposing a Stability Index (SI) based on cutting force variations during the cutting process. Using the FDEM method, we simulated the rock-breaking processes of planar, stinger, and machete cutters under various cutting depths and angles. SI and Mechanical Specific Energy (MSE) were employed as evaluation metrics to analyze the rock-breaking characteristics and determine the optimal cutting parameters for each cutter type. The results indicate that at shallow cutting depths, cutting force changes are minimal, predominantly causing plastic damage to the rock, resulting in lower stress and reduced wear on the PDC cutters. Conversely, at greater cutting depths, significant fluctuations in cutting force occur, leading to brittle failure and the generation of large cuttings. This sudden increase in cutting force can accelerate rock breaking but also increases the risk of cutter wear. Our findings suggest that the planar cutter offers stable performance with high cutting force requirements, optimal at a cutting depth of 1.5 mm and an angle of less than 20°. The stinger cutter, requiring lower cutting forces, performs best at a cutting depth of 2 mm and an angle of 20°. The machete cutter exhibits characteristics similar to the stinger cutter at shallow depths and the planar cutter at deeper depths, making it suitable for drilling at a depth of 2 mm and an angle of less than 10°. By balancing SI and MSE, this study provides a comprehensive approach to optimizing PDC cutter performance, enhancing drilling efficiency while minimizing cutter wear.
随着石油生产越来越多地从浅层地层向深层地层转变，使用高效的聚晶金刚石复合片（PDC）刀具钻穿深部硬岩变得至关重要。目前，缺乏优化刀具形状及其切削参数的有效方法。本研究通过建立PDC刀具破岩机理模型并基于切削过程中切削力变化提出稳定性指数（SI）来解决这一差距。使用离散元法（FDEM），我们模拟了平面、阶梯和弯刀刀具在不同切削深度和角度下的破岩过程。采用SI和机械比能（MSE）作为评价指标，分析破岩特性并确定每种刀具类型的最佳切削参数。结果表明，在浅切削深度下，切削力变化最小，主要导致岩石发生塑性破坏，导致应力降低和PDC刀具磨损减少。相反，在较大切削深度下，切削力会出现显著波动，导致脆性破坏并产生大块岩屑。切削力的这种突然增加可以加速破岩，但也增加了刀具磨损的风险。我们的研究结果表明，平面刀具性能稳定，但需要较高切削力，在切削深度为1.5毫米且角度小于20°时最佳。阶梯刀具所需切削力较低，在切削深度为2毫米且角度为20°时性能最佳。弯刀刀具在浅深度时表现出与阶梯刀具相似的特性，在深深度时表现出与平面刀具相似的特性，使其适合在切削深度为2毫米且角度小于10°时进行钻进。通过平衡SI和MSE，本研究提供了一种优化PDC刀具性能的综合方法，提高钻进效率同时最小化刀具磨损。
