Reservoir-condition pore-scale imaging of dolomite reaction with supercritical CO2 acidified brine: Effect of pore-structure on reaction rate using velocity distribution analysis. (January 2018)

• Record Type: Journal Article
• Authors: Al-Khulaifi, Yousef; Lin, Qingyang; Blunt, Martin J.; Bijeljic, Branko
• Is Part Of: International journal of greenhouse gas control. Volume 68(2018)
• Page Start: 99
• Page End: 111
• Publication Date: 2018-01
• Subjects: Carbon storage -- Carbonate dissolution -- Dolomite -- Pore-scale -- Effective reaction rate -- Micro-CT; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2017.11.011
• Languages: English
• ISSNs: 1750-5836

Abstract

Highlights: Dolomite core effective reaction rates are 5-38 times lower than batch rate. Permeability changes differ dramatically with initial heterogeneity at low rates. No impact of initial rock heterogeneity on dissolved permeability at high flow rate. Higher heterogeneity give more stagnant regions at low flow rate slowing reaction. Higher flow rate dissolution results in a more homogeneous velocity distributions. Abstract: To investigate the impact of rock heterogeneity and flowrate on reaction rates and dissolution dynamics, four millimetre-scale Silurian dolomite samples were pre-screened based on their physical heterogeneity, defined by the simulated velocity distributions characterising each flow field. Two pairs of cores with similar heterogeneity were flooded with supercritical carbon-dioxide (scCO2 ) saturated brine under reservoir conditions, 50 °C and 10 MPa, at a high (0.5 ml/min) and low (0.1 ml/min) flowrate. Changes to the pore structure brought about by dissolution were captured in situ using X-ray microtomography (micro-CT) imaging. Mass balance from effluent analysis showed a good agreement with calculations from imaging. Image calculated reaction rates ( reff ) were 5-38 times lower than the corresponding batch reaction rate under the same conditions of temperature and pressure but without mass transfer limitations. For both high (Péclet number = 2600-1200) and low (Péclet number = 420-300) flow rates, an impact of the initial rock heterogeneity was observed on both reaction rates and permeability-porosity relationships.