Dataset supporting publications: "Discrete Element Modelling of Rock Drilling" and "Towards Discrete Element Modelling of Rock Drilling"

Dataset supporting publications: Paper - “Discrete Element Modelling of Rock Drilling” and Thesis - “Towards Discrete Element Modelling of Rock Drilling” (both publications available in Zenodo: paper, thesis) Dataset used: Wear test datasets as described in T2.3.1 for the improvement of drilling efficiency via the selection of optimal drill bits (D5), Mechanical properties rock/soil (D29), Datasets resultant from numerical simulations of the drilling operation in T7.2-5 (D33) Percussive rotary drilling is recognized as the most efficient method for hard rock drilling. Despite clear advantages over conventional rotary methods, there are still some uncertainties associated with percussive drilling. For geothermal applications, drilling accounts for a large portion of the total cost. Specifically, the wear of drill bits when drilling in hard rock is a predominant cost factor and drilling parameters are often based on the experience of the field operator. Within the framework of the H2020 project GEOFIT, numerical simulations of percussive drilling are performed in order to evaluate the rock drilling process and gain insight about the trade-off between wear and Rate of Penetration (ROP). In the simulations, the rock material was represented by the Bonded Discrete Element Method (BDEM), the drill bit by the Finite Element Method (FEM), the drilling fluid by the Particle Finite Element Method (PFEM) and the abrasive wear on the surface of the drill bit was represented by Archard’s wear law. The drilling simulations were conducted for two rock materials; a sedimentary rock material corresponding to what was found when drilling at the GEOFIT pilot site in Aran Islands, Ireland, and a harder reference rock similar to granite. The results show that, at a drill bit impact force of 10 kN, the ROP in the sedimentary rock was 6.3 times faster than for granite. When increasing the impact force to 40 and 50 kN, however, the ROP for the sedimentary rock is only 1.9 and 1.6 times faster, respectively. Furthermore, the wear rate decreased with increased impact force when drilling in the granite rock. For the sedimentary rock, however, the loading resulting in the best trade-off between abrasive wear and ROP was the second highest loading of 40 kN, which suggests that an increase in impact energy may increase the rate of penetration but may not be economically motivated.

本数据集支撑以下发表成果：学术论文"Discrete Element Modelling of Rock Drilling"（《离散元建模在岩石钻进中的应用》）与学位论文"Towards Discrete Element Modelling of Rock Drilling"（《面向岩石钻进的离散元建模研究》），两篇成果均已在Zenodo平台公开：论文链接、学位论文链接。
本数据集包含如下内容：T2.3.1中描述的磨损测试数据集（用于通过优选最优钻头提升钻进效率（D5））、岩土力学特性数据集（D29），以及T7.2-5章节中针对钻进作业开展数值模拟所得到的数据集（D33）。
冲击回转钻进（percussive rotary drilling）被公认为硬岩钻进领域效率最高的方法。尽管相较于常规回转钻进方法具备显著优势，但冲击钻进仍存在诸多待解决的不确定性。在地热开发应用中，钻进成本占项目总成本的极高比例，具体而言，硬岩钻进过程中钻头磨损是最主要的成本驱动因素，而当前钻进参数的选取往往依赖现场操作人员的经验。
在欧盟地平线2020（H2020）计划GEOFIT项目框架下，本研究开展冲击钻进数值模拟，旨在评估岩石钻进过程，并深入探析钻头磨损与机械钻速（Rate of Penetration, ROP）之间的权衡关系。
本次模拟中，岩体采用粘结离散元法（Bonded Discrete Element Method, BDEM）进行建模，钻头采用有限元法（Finite Element Method, FEM）建模，钻进流体采用粒子有限元法（Particle Finite Element Method, PFEM）建模，钻头表面的磨粒磨损则通过阿查德磨损定律（Archard’s wear law）进行表征。
本次钻进模拟针对两种岩体开展：一种为对应爱尔兰阿兰群岛GEOFIT试验场址钻进工况的沉积岩，另一种为性质类似花岗岩的高硬度参考岩体。
研究结果显示，当钻头冲击力为10 kN时，沉积岩的机械钻速为花岗岩的6.3倍。然而当冲击力提升至40 kN与50 kN时，沉积岩的机械钻速仅分别为花岗岩的1.9倍与1.6倍。此外，在花岗岩钻进过程中，磨损速率随冲击力增大而降低；但对于沉积岩而言，实现磨粒磨损与机械钻速最优权衡的载荷为第二高的40 kN冲击力，这意味着提升冲击能量虽可提高机械钻速，但未必具备经济可行性。