  An optimization procedure for sealing leakage paths in field-scale
application of microbially induced calcite precipitation (MICP) is develop and
applied to CO$_2$ storage. The procedure utilizes a recently developed
field-scale MICP mathematical model implemented in the industry-standard
simulator Open Porous Media (OPM) Flow. The optimization problem is solved
using the ensemble-based optimization (EnOpt) algorithm where the objective
function is defined such that maximizing calcite precipitation is done in the
shortest possible MICP operational time. An injection strategy is developed to
efficiently produce calcite in and around the leakage paths, and to avoid
clogging unwanted areas of the reservoir, e.g., the near-well area. The
injection strategy consists of combined injection of growth and cementation
solutions in separate well segments to initiate the MICP process after
establishing a biofilm in the leakage paths with an initial injection phase.
The optimization procedure is applied to three synthetic CO$_2$ leakage
scenarios. The numerical results show that the leakage paths in all scenarios
are effectively sealed while keeping the total MICP operational time low.
