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Advancing underground drilling with particle rheology
Appleby, Benjamin A.
Appleby, Benjamin A.
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2023
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Abstract
This thesis addresses material processing and technological challenges in underground drilling. Material processing includes the breakdown and fluidization of soil materials primarily composed of clay and granular particles at low (≥16.7wt% Solids) and high (≤3wt% Solids) water content. In chapter 3, for low water content soils, a viscometer was developed with a calibration procedure used for complex fluid samples with granular particles. This procedure was modified with the Bingham Plastic constitutive relationship to include shear-thinning/shear-thickening and yield stress behavior. This work expands viscometer capabilities to measure samples with particles surpassing 4cm in size and captures additional viscometric material properties. In chapter 4, for high water content soils, a flow loop was built to measure the viscometric power-law parameters of bentonite drilling fluid slurry with soil cuttings, cuttings returns. Learned from this work, classifying soil cuttings and drilling fluids by clay type, clay to sand ratio, and water content was not enough to capture viscometric differences between cuttings returns samples from a drill site compared to a model sample made in the lab.
Fluid circulation loss, one of the largest problems in underground drilling, was addressed with technological work. In chapter 5, a contra-rotating propeller pump system was built to evaluate the efficacy of installing pumps along a drill string to reduce drilling fluid pressures and prevent a fluid circulation loss event. Learned from this work, the design principles of single propeller pumps could not be applied to contra-rotating propellers and the separation distance between propellers play a major role in their performance. In chapter 6, fluid circulation loss to porous media was addressed. A porous media cylinder was built to model this scenario and used to learn that adding sand to either water or a bentonite slurry would clog a gravel bed and allow drilling fluid pressure to rebuild, preventing fluid circulation loss.
In summary, this thesis provides methods and tools to measure and quantify viscometric material properties of soil materials to understand its processing and engineering suggestions to manage drilling fluid pressure and avoid fluid circulation loss events.
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