Micro-CT Imaging of Chemical Dissolution of Carbonate Rock

Micro-CT Imaging of Chemical Dissolution of Carbonate Rock

The microstructure of carbonate rocks experiences significant changes under reactive processes, in particular chemical dissolution and deposition including dissolution-released fines migration occurring during acidizing of petroleum reservoirs. A better understanding of such changes at the pore scale and their influences on rock properties is of great value for the effective design and implementation of reactive processes in reservoirs. In this paper, we demonstrate the use of X-ray micro-computed tomography (micro-CT) to non-destructively visualize local porosity changes in a microporous carbonate core sample during chemical dissolution. A dissolution experiment in a carbonate core sample by a non-acidic solution is designed such that changes in pore space from before to after the reactant injection could be imaged in exactly the same locations using micro-CT at resolution of less than 5 μm. The micro-CT images reveal a quasi-uniform dissolution pattern in the core sample and allow characterizing the accompanying migration of fines within the core sample. The results provide insight into pore scale characterization of reactive flow processes and their effects on the evolution of rock properties.

The microstructure of carbonate rocks experiences significant changes under reactive processes, in particular chemical dissolution and deposition including dissolution-released fines migration occurring during acidizing of petroleum reservoirs. A better understanding of such changes at the pore scale and their influences on rock properties is of great value for the effective design and implementation of reactive processes in reservoirs. In this paper, we demonstrate the use of X-ray micro-computed tomography (micro-CT) to non-destructively visualize local porosity changes in a microporous carbonate core sample during chemical dissolution. A dissolution experiment in a carbonate core sample by a non-acidic solution is designed such that changes in pore space from before to after the reactant injection could be imaged in exactly the same locations using micro-CT at resolution of less than 5 μm. The micro-CT images reveal a quasi-uniform dissolution pattern in the core sample and allow characterizing the accompanying migration of fines within the core sample. The results provide insight into pore scale characterization of reactive flow processes and their effects on the evolution of rock properties.