Title: | Synchrotron-based pore-network modeling of two-phase flow in Nubian Sandstone and implications for capillary trapping of carbon dioxide | Authors: | Hefny, Mahmoud Qin, Chao Zhong Saar, Martin O. Ebigbo, Anozie |
Language: | eng | Keywords: | Carbon capture and storage;CO₂-plume geothermal;Nubian Sandstone (Egypt);Pore-network modelling;Residual trapping;Physics - Geophysics | Issue Date: | 1-Dec-2020 | Document Type: | Article | Journal / Series / Working Paper (HSU): | International Journal of Greenhouse Gas Control | Volume: | 30 | Abstract: | Depleted oil fields in the Gulf of Suez (Egypt) can serve as geothermal reservoirs for power generation using a CO₂-Plume Geothermal (CPG) system, while geologically sequestering CO₂. This entails the injection of a substantial amount of CO₂ into the highly permeable brine-saturated Nubian Sandstone. Numerical models of two-phase flow processes are indispensable for predicting the CO₂-plume migration at a representative geological scale. Such models require reliable constitutive relationships, including relative permeability and capillary pressure curves. In this study, quasi-static pore-network modelling has been used to simulate the equilibrium positions of fluid–fluid interfaces, and thus determine the capillary pressure and relative permeability curves. Three-dimensional images with a voxel size of 0.65 μm3 of a Nubian Sandstone rock sample have been obtained using Synchrotron Radiation X-ray Tomographic Microscopy. From the images, topological properties of pores/throats were constructed. Using a pore-network model, we performed a sequential primary drainage, main imbibition cycle of quasi-static invasion in order to quantify (1) the CO₂ and brine relative permeability curves, (2) the effect of initial wetting-phase saturation (i.e. the saturation at the point of reversal from drainage to imbibition) on the residual-trapping potential, and (3) study the relative permeability-saturation hysteresis. The results improve our understanding of the potential magnitude of capillary trapping in Nubian Sandstone, essential for future field-scale simulations. |
Organization Units (connected with the publication): | Hydromechanik | URL: | http://arxiv.org/abs/2004.06792v1 | ISSN: | 1750-5836 | Publisher DOI: | 10.1016/j.ijggc.2020.103164 |
Appears in Collections: | 3 - Publication references (without fulltext) |
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