Temporary sealing of porous media through bio-clogging

Abstract

Ensuring the safe abandonment of a hydrocarbon or geological carbon storage reservoirs requires plugging the wells by installing fluid barriers within the wellbore. A pressure rise due to reservoir fluid flow poses a significant challenge. To prevent the fluid flow, temporary sealing of the porous medium surrounding the wellbore is essential. A promising approach for clogging the porous medium is the bio-mineralization technique. This study employs a large-scale model to simulate the permeability reduction patterns through microbially induced caclite precipitation (MICP). The focus is to provide realistic predictions by verifying the simulation with the results of batch and core-scale experimental analysis. The simulation domains include different systems with heterogeneous porosity and permeability distributions. This study characterizes the different biofilm development patterns in porous medium depending on the fluid velocity (up to 200 cm/h in this study), bacterial concentration and ionic strength of the bacterial solution. Additionally, the study analyses the uncertainties associated with bacterial growth and encapsulation. The simulation results show a significant variability in urea conversion factor during sequential treatment cycles, which ranged from 8 % to 83 % depending on the bacteria concentration, flow rate, and urea concentration. The results underscore the importance of estimating the critical pore diameter to more accurately predict clogging behavior in porous media with both high and low permeability values. This, in turn, enhances the reliability of treatment plan designs, which reduces the costs and material consumption.