Large diameter drilling performance modelling - experimental and empirical approaches

Abstract

Accurate modelling and optimization of large diameter drilling performance is critical in the efficient planning and delivery of large diameter drilling projects like tunnel boring and raise boring. A recently proposed application of large diameter drilling is narrow vein mining. This innovative technique results in continuous mechanized excavation of narrow vein deposits. This thesis presents experimental and empirical investigation into large diameter drilling performance. The research started with rock property characterization: shale volume prediction and rock mass mechanical properties evaluation. An extensive literature review shows no correlation has been developed in the Niger Delta Basin to accurately predict shale volume based on gamma-ray logs. Additionally, no published work shows the evaluation of the mechanical properties of the rock mass in the field site. From work conducted as part of this research, rock mass properties were evaluated for the site. Another contribution to be made by this research is the investigation of disc cutter drilling performance at small installation radii using a rotary cutting machine. This study complements several studies on disc cutting drilling performance using linear cutting. The final scope of the research was the modelling of large diameter drilling performance using results obtained from a Full Field Trial conducted on a steep quartz vein-host rock system. The different empirical models initially developed during the research were deterministic, however, probabilistic models were proposed to capture the existing aleatory and epistemic uncertainties. The thesis concluded with showing the implication of large diameter drilling as a new narrow vein mining method on the comminution energy requirements during mineral processing.