Atomic Layer Deposition (ALD) of Al2O3 on tall multiwalled carbon nanotube forests shows concentration variation with the depth in the form of discrete steps. While ALD is capable of extremely conformal deposition in high aspect ratio structures, decreasing penetration depth has been observed over multiple thermal ALD cycles on 1.3 mm tall multiwalled carbon nanotube forests. SEM imaging with Energy Dispersive X-ray Spectroscopy elemental analysis shows steps of decreasing intensity corresponding to decreasing concentrations of Al2O3. A study of these steps suggests that they are produced by a combination of diffusion limited delivery of precursors with increasing precursor adsorption site density as discrete nuclei grow during the ALD process. This conceptual model has been applied to modify literature models for ALD penetration on high aspect ratio structures, allowing several parameters to be extracted from the experimental data. The Knudsen diffusion constant for trimethylaluminum (TMA) in these carbon nanotube forests has been found to be 0.3 cm2s-1. From the profile of the Al2O3 concentration at the steps, the sticking coefficient of TMA on Al2O3 was found to be 0.003.

Zeolite membranes have great potential in gas separation applications because of their unique selective properties. The main challenge is in synthesizing defect-free zeolite membranes. In this study, we synthesized silicalite-1 zeolite membranes on ceramic supports composed of Al2O3 and TiO2 using the pore-plugging method. We investigated the effect of the fill-level in the autoclave during the synthesis on the membrane performance. In particular, we were interested in determining the conditions at which the defects' contribution to the total transport is minimized. We adopted and further developed the approach proposed by Carter (2019) to quantify the permeance contribution through defects. Comparing the membrane performance before and after calcination, we proposed several modifications to the original analysis of Carter (2019). Knowing the defect transport contribution, we determined the corrected diffusivity, an intrinsic property of zeolite crystals at a given temperature, of several adsorbed gases on silicalite-1 crystals. The defect's contribution decreased as the autoclave fill-level increased from 94 to 98%. A further increase in the autoclave fill-level introduced more defects and caused the autoclave lid to rupture. Despite the differences in the membranes' performance arising from the autoclave fill-level, the corrected diffusivities of CO2, CH4, and N2 in silicalite-1 showed minimal variation from membrane to membrane. This proves the validity of the proposed characterization method. Moreover, the reported corrected diffusivities are comparable to the literature's values, found using other characterization methods. However, none of the previously used methods is as simple and straightforward as the one we further developed in this study.

The main objective of this dissertation is to quantify petrophysical properties of conventional and unconventional reservoirs using a mechanistic approach. Unconventional transport mechanisms are described from the pore to the reservoir scale to examine their effects on macroscopic petrophysical properties in hydrocarbon-bearing organic shale. Petrophysical properties at the pore level are quantified with a new finite-difference method. A geometrical approximation is invoked to describe the interstitial space of grid-based images of porous media. Subsequently, a generalized Laplace equation is derived and solved numerically to calculate fluid pressure and velocity distributions in the interstitial space. The resulting macroscopic permeability values are within 6% of results obtained with the Lattice-Boltzmann method after performing grid refinements. The finite-difference method is on average six times faster than the Lattice-Boltzmann method. In the next step, slip flow and Knudsen diffusion are added to the pore-scale method to take into account unconventional flow mechanisms in hydrocarbon-bearing shale. The effect of these mechanisms is appraised with a pore-scale image of Eagle Ford shale as well as with several grain packs. It is shown that neglecting slip flow in samples with pore-throat sizes in the nanometer range could result in errors as high as 2000% when estimating permeability in unconventional reservoirs. A new fluid percolation model is proposed for hydrocarbon-bearing shale. Electrical conductivity is quantified in the presence of kerogen, clay, hydrocarbon, water, and the Stern-diffuse layer in grain packs as well as in the Eagle Ford shale pore-scale image. The pore-scale model enables a critical study of the [delta]LogR evaluation method commonly used with gas-bearing shale to assess kerogen concentration. A parallel conductor model is introduced based on Archie's equation for water conductivity in pores and a parallel conductive path for the Stern-diffuse layer. Additionally, a non-destructive core analysis method is proposed for estimating input parameters of the parallel conductor model in shale formations. A modified reservoir model of single-phase, compressible fluid is also developed to take into account the following unconventional transport mechanisms: (a) slip flow and Knudsen diffusion enhancement in apparent permeability, (b) Langmuir desorption as a source of gas generation at kerogen surfaces, and (c) the diffusion mechanism in kerogen as a gas supply to adsorbed layers. The model includes an iterative verification method of surface mass balance to ensure real-time desorption-adsorption equilibrium with gas production. Gas desorption from kerogen surfaces and gas diffusion in kerogen are the main mechanisms responsible for higher-than-expected production velocities commonly observed in shale-gas reservoirs. Slip flow and Knudsen diffusion marginally enhance production rates by increasing permeability during production. / text