Browsing by Author "Etemad, Sahand"

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    Micro-Scale Simulation of Evaporation, Condensation and Transport in Porous Media
    (2016) Etemad, Sahand; Kantzas, Apostolos; Hejazi, Hossein; Maini, Brij; Dong, Mingzhe
    Sub-pore scale modeling of flow in porous media is gaining momentum. The concept of Digital Core Analysis deals with measurements of virtual core and the purpose of such modeling is to replace conventional and special core analysis when the latter are not feasible. One of the challenging concepts in micro-scale simulation of porous media is consideration of phase change phenomena. Mass and heat transfer equations have to be considered simultaneously to capture complexities involved in the evaporation and condensation processes. Therefore, a numerical scheme based on the Volume-of-Fluid method was implemented using the OpenFOAM open-source CFD package along with four phase change models. The aforementioned approach is extended in the modeling of phase change within a porous medium. Surface roughness is introduced by the incorporation of wedges of variable density and amplitude on the grain surface. A further introduced complication is that the individual grains are of different mineralogy and thus of different wettability. It is observed that steam condenses first in the smallest of wedges, which act as nucleation sites. A condensate film was generated around high roughness density areas and the amount of condensate being generated in the roughened medium was significantly larger than the generated condensate in smooth surface. Water spreads on water-wet surfaces. Snap-off is observed in several cases leading to temporary trapping of vapor. Grid size effects are also addressed. The application of this modeling effort is the condensation of steam in thermal recovery methods. The effect of temperature on bitumen viscosity reduction during steam flooding operation as well as steam condensation, trapping of the oil behind the steam front and finally countercurrent flow of steam and condensate-bitumen due to gravity effects.
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    Mobility Control Using CNC Stabilized Carbon Dioxide Foams
    (2022-09) Etemad, Sahand; Kantzas, Apostolos; Bryant, Steven; Shor, Roman; Trifkovic, Milana; Yarranton, Harvey
    CO2 enhanced oil recovery is considered a practical technique to improve oil production, but also an option to alleviate carbon emission problems through CO2 capture and storage in deep geologic formations. Use of CO2 foam is a solution to poor gas sweep efficiency by reducing the gas phase mobility. The efficiency of the conventionally surfactant stabilized foams is jeopardized under reservoir conditions. Using biomass-derived materials to fortify foam is new for oil production. The application of biomass-derived materials such as Cellulose Nanocrystals (CNC) as the basis for generating foams will open a new market for Alberta’s forestry and bio industries. InnoTech Alberta is producing CNC from wood pulp and paper processing waste, the most common feedstock for CNC. There is a lack of research and technology demonstrating the advantage of biomass-derived nanomaterials at reservoir conditions for CO2 EOR processes. We experimentally investigate the performance of a foam system consisting of a surfactant with the addition of CNC for operation at up to 2.8MPa pressure and 115℃ temperature. Experiments are conducted under static and dynamic conditions. Foam volume, V(t), shows early linear and the later nonlinear drainage rate dependence with time. CNC in the continuous phase stabilize the CO2 in water foams by enclosing the droplets and reducing the collision. During a foam flood, oil in water emulsion stabilized by CNC, which initially appeared in the foam structure. Stable foam is generated via interactions of inexpensive CNC and cationic surfactants with concentration as low as 0.05wt%. Foamability defines as the initial capacity of the foaming solution to form foam. Half-lives and mobility reduction factors for the CNC foams were higher than the surfactant foams. Gas-water interfaces and liquid films within the foam structure showed more stability by adding CNC to surfactant solutions. CNC fortified the liquid films by blocking the liquid flow and increasing the viscosity. Additionally, CNC-stabilized foam had lower liquid drainage rate. The results of this work will provide baseline information for other research on CNC based fluids for underground applications. The target of this study is CO2 storage and flooding in conventional, hot conventional and viscous oil reservoirs.