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published_or_final_version / abstract / toc / Earth Sciences / Master / Master of Philosophy

published_or_final_version / abstract / toc / Applied Geosciences / Master / Master of Science

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In petroleum engineering and geophysics, it is often assumed that the rocks are completely rigid bodies with a totally interconnected pore space and that the fluid within the pores does not affect and are independent of the strains in the porous media. These assumptions are often not accurate and also unrealistic because the pore pressure effects are of great importance in all of the geomechanical processes occurring in the subsurface. The hydraulic and mechanical processes are coupled so that the rock deformation causes pore pressure changes and fluid flow (displacement relative to the solid). The time- dependent coupling of the hydraulic and mechanical processes can be described by the theory of poroelasticity. Application of this theory requires the availability of material parameters through experiments. In this work, the main poroelastic parameters are determined for some rock types of interest. The focus of this work is concentrated in low porosity rocks that are commonly encountered. Experimental procedures under drained, undrained and unjacketed conditions were initially completed in Berea Sandstone. Then, Indiana Limestone, Westerly Granite and Welded Tuff specimens were tested in order to obtain Skempton’s pore pressure parameter B, Biot’s coefficient of effective stress α, Bulk Modulus and Grain compressibility. Preliminary results suggest that the parameters B, K and α will change in accordance to the permeability and the porosity of the rock, while K_(S) would depend more on the mineralogy and deposition characteristics of the rock.

Size reduction represents one of the most energy-intensive and costly processes in the extraction of valuable minerals and rocks. Drilling and blasting, being the first operation in the size reduction chain, may have a significant downstream effect, influencing mine economics. This thesis investigates effects of blasting on subsequent size reduction operations. A series of small scale blasts have been conducted, and the fragments have been screened, drop weight tested, crushed and their Bond Work Index and breakage parameters have been determined. The process was repeated for 3 different types of granite blocks (Stanstead, Laurentian, and Barre granite) using samples not blasted previously and samples blasted with three different powder factors (0.391, 0.782, and 1.173kg/m3). As well, four types of different charge methods with the same powder factor were used to investigate the influence of blasting energy distribution on grindability in the case of Barre granite. Subsequently, stress wave collision blasting and the effect of delay timing were tested under the same powder factor conditions. Generally, powder factor resulted in the most significant changes in the breakage parameters as well as fragmentation. The Bond Work Index showed a small decrease as a function of powder factor, which can be considered to be material dependent. There is indication that distribution of charge resulted in better grindability while fragmentation seems to be similar in both cases and better than when air decking was used. The results from Barre granite showed clearly that stemming affected fragmentation by producing finer fragments. / Thesis (Master, Mining Engineering) -- Queen's University, 2010-04-23 12:49:29.244

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