Experimental Analyses of Pore‐Size Dependent Biomineralization in Porous Media Under Various Flow Rate and Bacterial Density Scenarios
Ze Yang, Zhi Dou, Alberto Guadagnini, Xiaoteng Li, Chaoqi Wang, Jinguo Wang
Abstract
Abstract We document results of a set of laboratory experiments aimed at exploring impacts of injection rate and bacterial density on biomineralization across water‐saturated porous media. The study relies on a Low‐Field Nuclear Magnetic Resonance technology and the ensuing transverse spin‐spin relaxation time distributions. The latter is documented to provide a robust quantification of temporal histories of pore size distributions during biomineralization. As such, our work explores and quantifies pore‐size dependent biomineralization across the three‐dimensional pore space. The study also provides a quantitative analysis of alterations in porosity and permeability induced by biomineralization, together with a quantification of (time‐averaged) rates of pore volume change. A plugging ratio efficiency index is introduced to quantify the strength of pore‐size‐related biomineralization. Our results reveal that biomineralization induces significant alterations in the pore size distribution within a porous medium, these changes being modulated by bacterial density and injection rate. We find that CaCO 3 mainly precipitates in macropores, consistent with the presence of favorable local hydrodynamic conditions and large surface areas therein. Precipitated CaCO 3 volume is found to increase with bacterial density. High bacterial densities amplify rate of pore volume change within macropores and adequate plugging ratio of biomineralization and contribute to a significant permeability reduction. Otherwise, a diminished strength of biomineralization in mesopores and micropores is documented for the highest injection rates considered.