Events

Dr. Rouhi Farajzadeh, Senior Reservoir Engineer with Shell, and Part-time Assistant Professor of Reservoir Engineering at Delft University of Technology, the Netherlands, will give a talk entitled "Enhanced transport phenomena in CO₂ sequestration" as part of the Claude R. Hocott Graduate Seminar Series. 

Abstract: 
Efficient storage of carbon dioxide (CO₂) in aquifers requires dissolution in the aqueous phase. Indeed the volume available for gaseous CO₂ is less than for dissolved CO₂. The mass transfer between CO₂ and underlying brine in aquifers causes a local density increase, which induces convection currents increasing the rate of CO₂ dissolution. This system is gravitationally unstable and leads to unstable mixing enhancement in the aquifer. The efficiency of mixing in density-driven natural-convection is largely governed by the aquifer permeability, which is heterogeneous in practice. The character (fingering, stable mixing or channeling) of flow-driven mixing processes depends primarily on the permeability heterogeneity character of the aquifer, i.e., on its degree of permeability variance (Dykstra–Parsons coefficient) and the correlation length. We follow the ideas of Waggoner et al. (1992) to identify different flow regimes of a density-driven natural convection flow by numerical simulation.

Moreover, we extend Koval’s method to analytically model gravitationally unstable flow in porous media. We find that downstream of the diffusive layer, the solution of the convective part of the model, is a rarefaction solution that starts at the saturation corresponding to the highest value of the fractional-flow function. A comparison of the Koval model with the horizontally-averaged concentrations obtained from 2-D numerical simulations provides a correlation for the model parameters with the Rayleigh number. The obtained scaling relations can be used in numerical simulators to account for the density-driven  natural convection, which cannot be currently captured because the grid cells are typically orders of magnitude larger than the wavelength of the initial fingers. The method can be applied both for storage of greenhouse gases in aquifers and for EOR processes using carbon dioxide or other solvents.

Bio:
Rouhi Farajzadeh is a senior reservoir engineer with Shell and a part-time assistant professor of reservoir engineering at Delft University of Technology, the Netherlands. He holds PhD and MSc in Petroleum Engineering from TU Delft (both with Cum Laude) and a BSc in Chemical Engineering from Tehran Polytechnique. He has worked on variety of research projects including CO₂ sequestration, EOR processes (gas, chemical, solvents), flow and transport in porous media, and surface and colloidal chemistry. He is also a visiting scholar to Rice University since 2012. He is an associate editor of Journal of Petroleum Science and Engineering and serves as technical editor for more than 10 journals. He is also a member of CO₂ capture, utilization, and storage (CCUS) section of SPE.