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A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Environmental Systems Engineering, University of Regina. xvi, 247 p. The Canadian Prairies has the highest water demand-to-availability ratio in Canada. The region is characterized by a scarcity of water resources because evaporation generally exceed precipitation. Evaporation is a complex phenomenon based on interactions between meteorological and physiological factors. The purpose of this research was to accurately determine evaporative flux from water and soil surfaces. The main research contributions of this research are summarized as follows: (i) a Bench-scale Atmospheric Simulator (BAS/BAS2) was developed to control artificially generated parameters for short time periods; (ii) a Controlled Photogrammetry System (CPS) using Structure-from-Motion (SfM) technology was developed for accurate and non-destructive measurement of dimensional changes during evaporation; (iii) high-quality evaporation datasets were developed for calibration of devices, validation of prediction equations and evaluation of theoretical frameworks; (iv) predictive models for evaporation from water were evaluated to select appropriate empirical equations for predicting potential evaporative flux from water; and (v) a theoretical framework for evaporation from soils was developed to correlate with soil behavior (water retention and soil shrinkage) for both fresh water and saline water. The findings of this research are useful for developing methods to minimize evaporation and for helping with devising water use policy. Student yes

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Geology, University of Regina. ix, * 216. Saskatchewan is home to world-class uranium (U) deposits associated with the unconformity between the Proterozoic Athabasca Basin and underlying Archean- Paleoproterozoic basement rocks. Many deposits exhibit a strong spatial association with post-Athabasca faults formed by the reactivation of basement-rooted structures. Deformation bands are products of localized strain in porous sedimentary rocks and are commonly associated with fault damage zones. They can significantly modify porosity due to grain rotation and granular flow. This study investigated deformation bands in sandstones of the basal Manitou Falls Group in eight drillhole fences that transect two fault corridors in the eastern Athabasca Basin: the NNE-trending C1 fault corridor that hosts the Gryphon deposit, and the WS shear zone, a splay of the former that hosts the Phoenix deposit. The deformation bands in the sandstone correspond to mainly shearenhanced compaction bands that increase in abundance toward post-Athabasca faults. The proportion of bands with visible signs of cataclasis increases with depth. Petrographic study places band formation relatively early in the host-rock paragenetic sequence, before introduction of drusy quartz veins and tourmaline associated with U mineralization. Paleo-stress analysis performed using basement- and sandstone-hosted structural orientation data identified two major stress regimes associated with each fault corridor. The first stress regime (A) groups strike-slip (cover) and thrust (cover and basement) solutions at both localities wherein the principal stress (σ1) lies in the horizontal plane roughly perpendicular to the fault; while the second regime (B) groups additional data, with the derived σ1 (~E–W) lying near-parallel to faults. Based on collective macroscopic to microscopic observations, deformation bands are inferred to have formed after Manitou Falls deposition in successive homogeneous stress regimes. It is contended that the bands initially formed in a strike-slip regime (A), characterized by subhorizontal NW–SE-trending σ1 that promoted reverse reactivation of moderately ESEdipping basement-rooted faults. A younger set of thrust-sense bands may have facilitated fault propagation through the sandstone cover, and potentially records the evolution of A to a fully contractional i.e., thrust regime. Most deformation bands thus appear to have formed early, under regional compression that preceded and accompanied basement fault reactivation that led to offset of the unconformity and influx of uraniferous fluids. The second regime (B, σ1 E–W) may mark younger sinistral strike-slip motion (basement and cover) which influenced the development of NW–SE transverse faults. The nature and timing of the bands in this study is compatible with the shallow basin model (

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Petroleum Systems Engineering, University of Regina. xxix, 267 p. With the hydrate development stepping into the field trials, technical challenges and operational concerns arise at the same time including the risk of geological disasters, unstable/discontinuous gas production rates, low energy efficiencies, and high sand influxes. To safely, economically, and efficiently develop a natural gas hydrate (NGH) reservoir in the future, it is of fundamental and practical importance to determine its physical properties, characterize the dynamic attributes along with hydrate extraction, and design and optimize the operational parameters for different dissociation techniques at both laboratory- and field-scales. An equivalent resistance model is proposed and validated to determine hydrate saturation based on the experimentally measured resistivity with consideration of sandstone skeleton, brine salinity, and formation tortuosity. Compared to the classic Archie formula, such an equivalent resistance model shows a better agreement with the experimental measurements and has a less dependence on the accuracy of porosity. Experimental and theoretical techniques have been developed to determine the dissociation front (i.e., the boundary where hydrate saturation is decreased to 0) for hydrate development by combining depressurization and hot brine stimulation. Simulation techniques are employed to determine the decay rate and relative permeability by fitting the experimental measurements and then extended to field applications by applying two different development methods. Two dissociation fronts are found to form separately near the producer and the injector for the combination method. Then, hydrate dissociation behaviour in a brine system by reducing the pressure below the quadruple point is both experimentally and numerically quantified. By approximating the energy contributions, it is found that sensible heat is supplied for hydrate dissociation at the initial stage and that heat conduction from boundary and ice fusion accelerates hydrate dissociation at the final stage. The fluid flow and hydrate dissociation kinetics are found to play a dominant role above the freezing point, while, below the freezing point, the significance of heat conduction from boundary and ice fusion are enhanced during the experiments. Experimentally, sand detachment, migration within matrix, invasion to gravel packing, and production are microscopically observed for openhole gravel-packing with the clayey-silt sediments collected from the Shenhu area of the northern South China Sea. Fractures, wormholes, and fluidized channels are successively developed with a large amount of sand production as well as variations on inlet pressure. Subsequently, the experimental techniques are further modified and improved to eliminate the associated uneven strain-stress effect to microscopically depict sand failure dynamics, sand flow paths, and sand production for wormholes. Theoretically, a wormhole growth model has been proposed to reproduce the sand production for both hydrate-free and hydrate-bearing sandpacks by considering a pressure-gradient-based (PGB) sand failure criterion as well as the porosity and permeability alteration models. The experimental measurements show that a predesigned hydraulic slotting after well completion would decrease the hydraulic gradient near the wellbore and thus decrease the possibility of sand failure. Similar to hydrate production, sand production is also divided into three stages, i.e., before hydrate dissociation, during hydrate dissociation, and after hydrate dissociation. Student yes

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Petroleum Systems Engineering, University of Regina. XXIX*, 240 p. Imbibition pervasively exists in many natural and industrial processes, such as oil/gas recovery, hydraulic fracturing, the postinjection stage of CO2 sequestration, printing processes, diagnostic tests in biomedicine. As a dominant mechanism in tight formations, imbibition has been extensively studied across scales to support world energy demands and environmental requirements of carbon neutrality. Many studies indicate that macroscale performances, like the displacement front instability and residual saturation of the non-wetting phase, highly depend on flow behaviors at the pore-scale level. Despite the importance of pore-scale imbibition processes in tight rocks, many previous studies have been conducted lack considering typical pore-throat features in tight rocks or single-phase flow systems. In this thesis, we employ the analytical, experimental, and numerical methods to study pore-scale imbibition behaviors in pore-throat structures with tight rock features for both liquidgas (L-G) and liquid-liquid (L-L) systems. The analytical portion focuses on imbibition behaviors in microcapillaries with varying cross-sections, emphasizing the effects of viscosity ratios on the equivalent capillary radius and different fluid systems. A modified imbibition equation with an equivalent straight capillary is developed for complex capillaries. The results indicate that at the early stage of imbibition (Zx≤0.12Ψ/(Ψ-1)), the modified imbibition equation can be reduced to a power-law correlation, i.e., Zx∝ 1/Ψα t, where α≈1.025. After that stage, the accuracy of using the power-law correlation begins to decrease. In general, it is more suitable to express the imbibition equations in a quadratic equation, especially for liquid-liquid imbibition systems. In the experimental portions, we quantitively investigate imbibition dynamics in single pore geometries that consider 2D pore-scale characteristics of tight rocks with an etching depth higher than the critical geometric criteria for including 3D features. The typical pore/throat features in tight rocks are summarized and guide for designing the 2D micromodel. The combined effects of the capillary number, fluid properties, and pore-throat structures on imbibition performances are comprehensively discussed. The results demonstrate that with the pore-throat aspect ratio increasing, combined effects of the capillary number, pore shape, outlet throat width (i.e., the flow direction in this work) on non-wetting phase entrapments become more significant. After a critical capillary number, the pore-filling fractions are linearly positive related to the capillary number regardless of the pore shape or outlet throat width, especially for tested macropores. Moreover, attempts, challenges, and recommendations for imbibition studies in 2D and 2.5D micromodels are also documented to guide future researchers. For the numerical simulation portions, we investigate the feasibility of the phase-field method (PFM) in reproducing the strong imbibition dynamics in microcapillaries with typical pore-throat features in tight rocks. In general, the results demonstrate that the PFM simulations can successfully match the imbibition behaviors (such as piston-like movement and wetting film flow) in most micro and mesopores. However, they are challenging to simulate pore-throat structures with an aspect ratio higher than 100 because of convergence problems. The simulation results also agree with the critical contact angle for precursor film flow and find a new type of capillary barrier related to pore shapes in strong imbibition processes. Student yes

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Petroleum Systems Engineering, University of Regina. xlii, 363 p. In addition to conventional enhanced oil recovery (EOR) technologies, extensive efforts have been made to explore new approaches to sustain the increasing global oil and gas consumption while lowering the operational costs. In recent decades, nanoparticles (NPs) have seen their promising potentials in recovering hydrocarbons from numerous laboratory experiments and field pilots. Also, hydraulic fracturing techniques have unlocked a significant quantity of hydrocarbon resources from unconventional reservoirs. Solid particle transport including NP transport, dispersion, and distribution in hydrocarbon reservoirs, proppant placement within hydraulic fractures, and sand production is critical to the efficient and effective hydrocarbon exploitation. Considering the petrophysical complexity as well as the intricate interactions among particles, fluids, and rock matrix, it is, therefore, an extremely challenging task to accurately predict the associated transport and placement behaviour of solid particles in a hydrocarbon reservoir. Theoretically, a robust and pragmatic method has been developed and validated to analytically determine the dynamic dispersion coefficients for particles flowing in a parallel-plate fracture with instantaneous point source as well as uniform and volumetric line sourcess, in which particle gravity settling effect has been considered. It is found that the point source and the uniform line source are respectively the most and least sensitive to the gravity effect. An increase of particle size larger than its critical value decreases the asymptotical dispersion coefficient for all the source conditions, while gravity settling promotes the dispersion phenomenon during the early-stage of point source condition. Particle-tracking simulations have been performed and validated on polydisperse dense particle transport in a randomly-orientated fracture with spatially variable apertures. The simulated results indicate that the mass breakthrough efficiency of particles and particle plume distribution in a randomly-orientated rough fracture are significantly influenced by different factors when particle gravity settling occurs. In addition, particle attachment consisting of reversible and irreversible adsorptions on an aperture surface is quantified applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) kinetics. With sensitivity analysis performed, the impacts of different factors on particle attachment are found to vary with each other through non-unique patterns. By integrating the Perkins-Kern-Nordgren-Carter (PKN-C) fracture propagation model and the particle tracking algorithm, a novel Eulerian-Lagrangian (E-L) model has been developed and validated to simulate field-scale proppant transport during hydraulic fracturing operations. Such an E-L model incorporates pertinent empirical correlations determined from regressing experimental measurements regarding the proppant settling velocity and the drag/lift forces, which is applicable to both the Newtonian and non- Newtonian fluid conditions. The non-Newtonian fluid is usually found to yield a less “heel-biased” pattern of proppant distribution in a hydraulic fracture, e.g., a larger slurry coverage together with a longer proppant dune, while distinct patterns of the dominant factors are observed and evaluated. Student yes