  Microbially induced calcite precipitation (MICP) is a new and sustainable
technology which utilizes biochemical processes to create barriers by calcium
carbonate cementation; therefore, this technology has a potential to be used
for sealing leakage zones in geological formations. The complexity of current
MICP models and present computer power limit the size of numerical simulations.
We describe a mathematical model for MICP suitable for field-scale studies. The
main mechanisms in the conceptual model are as follow: suspended microbes
attach themselves to the pore walls to form biofilm, growth solution is added
to stimulate the biofilm development, the biofilm uses cementation solution for
production of calcite, and the calcite reduces the pore space which in turn
decreases the rock permeability. We apply the model to study the MICP
technology in two sets of reservoir properties including a well-established
field-scale benchmark system for CO$_2$ leakage. A two-phase flow model for
CO$_2$ and water is used to assess the leakage prior to and with MICP
treatment. Based on the numerical results, this study confirms the potential
for this technology to seal leakage paths in reservoir-caprock systems.
