Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

Sadighian, Ardalan; Becerra, Mildred; Bazyleva, Ala; Shaw, John M.

doi:10.1021/ef101435r

Cited by 15 publications

(18 citation statements)

References 26 publications

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“…Athabasca bitumen derived samples:Athabasca bitumen + pentane11 ; Athabasca atmospheric residue + pentane14 , Athabasca vacuum residue + pentane 14 ; ■ Athabasca bitumen + toluene 13 ; Athabasca bitumen + toluene (this work) , 273 K, ► 298 K and ◄ 313 K.…”

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confidence: 88%

Fickian and Non-Fickian Diffusion in Heavy Oil + Light Hydrocarbon Mixtures

Alizadehgiashi

Shaw

2015

Energy Fuels

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Diffusive mass transfer is expected to play a key role in existing and proposed solvent-added processes for heavy oil production. Composition-distance profiles arising during free diffusion scale as a function of the joint variable (distance/time^n w ). Simple fluids are governed by Fickian diffusion, where n w = 0.5. For nanostructured fluids the value of n w can be as low as n w = 0.25, known as the single file limit but more typically the value for the exponent falls between these two limits and is composition dependent. In this work, five published data sets comprising free diffusion composition profiles for Athabasca bitumen fractions and for Cold Lake bitumen + light hydrocarbons obtained using diverse apparatus, are probed from this perspective.Additional experimental results are provided for Athabasca bitumen + toluene mixtures over the temperature range 273 to 313 K, and results from positive and negative control experiments for two well-defined mixtures: (0.25 mass fraction carbon nanotubes + polybutene) + toluene, and polybutene + toluene, are also provided. The value of n w for the negative control experiment remains at 0.50 +/-0.05 over the entire composition range and for the positive control experiment, the value drops to n w = 0.30 +/-0.02 at low toluene mass fraction. While the quality of the diffusion profile data in the data sets analyzed is variable, the values of the exponent n w are shown to be light hydrocarbon dependent and increase from n w ~ 0.25 at low light hydrocarbon mass fraction up to n w ~ 0.50 at high light hydrocarbon mass fraction. Secondary convective effects are also noted in free diffusion experiment outcomes at long times. The industrial applications of these finding are currently being evaluated but it is clear that the time for light hydrocarbons to penetrate a fixed distance into nano-and micro-structured hydrocarbon resources is greater than the value anticipated for unstructured fluids.

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confidence: 88%

Fickian and Non-Fickian Diffusion in Heavy Oil + Light Hydrocarbon Mixtures

Alizadehgiashi

Shaw

2015

Energy Fuels

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“…The phase behavior of propane + Peace River bitumen was studied using a custom X-ray view cell developed specifically for opaque mixtures such as bitumen and heavy oil. The equipment, used in numerous studies, ,− is described in detail elsewhere . Only a brief description is provided here.…”

Section: Methodsmentioning

confidence: 99%

Phase Behavior and Thermophysical Properties of Peace River Bitumen + Propane Mixtures from 303 K to 393 K

2016

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Propane and mixtures including propane as a principal component are among the leading potential candidates for co-injection along with steam for improving the process and environmental efficiency of oil sands bitumen production processes. Phase diagrams and thermophysical property data enable technologies for the development and optimization of such processes. In this work, phase behavior, phase composition, and phase densities of propane + Peace River bitumen mixtures are reported in the temperature range 303 to 393 K at pressures ranging from 1 to 6 MPa. The phase behavior of this pseudobinary mixture can be categorized as Type III according to the van Konynenburg–Scott nomenclature. Pressure–temperature at fixed composition, and pressure–composition at fixed temperature phase diagrams, and pressure–temperature phase projections are presented, along with saturated compositions and densities of the coexisting bitumen-saturated propane liquid (L1) and propane-saturated bitumen liquid (L2) phases. Saturated L1 and L2 phases are both significantly less dense than liquid water phases at the same temperatures and pressures, and the volumes of mixing, particularly for the L1 phase, are large and negative. This data set provides a benchmark for process development and process design calculations for ongoing bitumen production and deasphalting applications.

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“…For example, liquid-phase mutual diffusion coefficients for solvents in heavy oils and bitumen are bounded by theory and for specific cases best obtained from the direct measurement of local composition profiles within a liquid phase. − Reported mutual diffusion coefficient values, under ambient conditions, are low (∼10 –10 m 2 /s), and the corresponding measured solvent penetration rates, over durations exceeding days, where the solvent is above and the bitumen or heavy oil is below the interface, are also low (∼0.01 μm/s). With forced convection, leading to high shear at a solvent–heavy oil or bitumen interface, penetration rates up to 3 orders of magnitude greater than those obtained for diffusive penetration alone can be realized (∼10 μm/s). While such enhanced penetration rates are consistent with conventional liquid–liquid and liquid–solid mass transfer predictive models and theory, the required shear rates cannot be realized without mechanical agitation and cannot be produced in a micro porous medium.…”

Section: Introductionmentioning

confidence: 94%

Discontinuous Displacement at Solvent–Immobile Hydrocarbon Interfaces

2020

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Concerns over the environmental impacts of thermal production methods for bitumen and heavy oil have led to the exploration of alternative technologies including solvent-assisted production methods. While solvent-assisted production methods have been studied extensively, the apparent diffusion coefficients of the penetrating solvent 1–2 orders of magnitude greater than those predicted for Fickian diffusion applicable to liquid mixtures are required to match production histories. “Surface renewal” and “sloughing” mechanisms have been advanced to explain these higher solvent penetration rates into reservoirs during production but have not been observed directly or included in physical models. In this work, we use high-resolution X-ray videography to investigate solvent penetration at interfaces between a model solvent (n-pentane) and model immobile reservoir fluid (octacosane) over time to observe “surface renewal” and “sloughing” directly for the first time. We show that for horizontal interfaces (octacosane below), interface displacement arises solely from diffusion and rates of displacement are slow (∼10–2 μm/s). For vertical pentane–octacosane interfaces and horizontal pentane–octacosane interfaces (pentane below), steady displacement rates, an order of magnitude greater than for diffusion alone, are punctuated by a rapid detachment of ∼30 μm layers of octacosane-enriched liquid from the interface at ∼150 s intervals. For vertical interfaces that dominate production processes especially in thin reservoirs, average interface displacement rates around 0.5 μm/s are realized. Our findings highlight the impact of interface orientation on interface displacement rate and provide quantitative insights into the kinetics of solvent-assisted bitumen and heavy oil production processes in high permeability reservoirs. Further experimental and theoretical study is required to understand and quantify interfacial displacement effects in low permeability reservoirs.

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Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

Cited by 15 publications

References 26 publications

Fickian and Non-Fickian Diffusion in Heavy Oil + Light Hydrocarbon Mixtures

Fickian and Non-Fickian Diffusion in Heavy Oil + Light Hydrocarbon Mixtures

Phase Behavior and Thermophysical Properties of Peace River Bitumen + Propane Mixtures from 303 K to 393 K

Discontinuous Displacement at Solvent–Immobile Hydrocarbon Interfaces

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