Disk cutter drilling performance and optimization methods, rock strength correlation and field data analysis

Mafazy, Salum (2023) Disk cutter drilling performance and optimization methods, rock strength correlation and field data analysis. Masters thesis, Memorial University of Newfoundland.

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Abstract

Drilling a rock near the ground surface has an increasing demand for natural resources exploration, such as the recovery of minerals or crushed rock, the application of tunneling in civil engineering, etc. A recent field mine drilling at Baie Verte, located in the North of Newfoundland, Canada, involved a diamond drilling hole (DDH) for core recovery, which was intended for lithology analysis and as a pilot hole and a large diameter hole drilling (LDH) for ore excavation. This thesis includes an investigation of mining drilling on the LDH to determine abnormal drilling low rate of penetration (ROP) performance at a specific depth interval, where drilling data was analyzed based on each lithology. Also rock material characterization was conducted on granite rock to introduce a new method of Semi-Point Load Strength Index (Semi-PLSI) for estimation of the rock strength, and a detailed analysis of the effect of microwave irradiation on rock properties as one of the influencing technology of an increasing ROP. The above studies involve several laboratory tests, which include detailed rock core logging, mechanical tests, cutting size analysis, and mineral liberation analysis (MLA). The study of drilling performance at specific interval was influenced by high rock strength which was caused by a variation of rock micro-structure determined by MLA technology. Also, the rock characterization study of a new approach of Semi-PLSI shows excellent correlation and strength estimation with standard PLSI and other strength tests. Additionally, microwave irradiation (MI) analysis shows a decrease in strength, ultrasound wave velocities and elastic constants of the rock after the rocks are exposed to MI. Also, the effects of MI observed to increase drilling rate of penetration (D-ROP) of the rocks.

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