Erosion and clogging mitigation in sandstone reservoirs through microbial carbonate precipitation: A microfluidic study

Erosion and clogging near CO₂ injection wells present significant challenges to reservoir stability and injectivity, especially in weakly consolidated sandstones containing carbonate minerals. In this study, microfluidic chips were used to construct synthetic porous media mimicking weakly cemented sandstone, followed by Microbially Induced Calcium Carbonate Precipitation (MICP) treatment to reinforce pore structure and improve resistance to acid-induced degradation. Systematic experiments were conducted under varying pH, flow rates, and treatment cycles to simulate CO₂-induced acidic flow conditions. Results demonstrate that MICP significantly enhances erosion resistance by forming multiscale CaCO₃ networks through particle bridging and interfacial cementation. A size-dependent buffering effect is observed during crystal dissolution, where smaller crystals dissolve first, locally increasing pH and delaying damage to larger structures. MICP also mitigates clogging by forming permeable crystal bridges at pore throats, restricting coarse particle transport while maintaining flow paths. The extent of erosion and clogging is strongly correlated with the initial cementation volume ($V_{{\mathrm{CaCO}}_3}/V_V$), showing a dual-threshold response: systems with ≥4 % CaCO₃ remain stable, while those with <2 % rapidly destabilize. MICP treatment raises the critical flow threshold and reduces sensitivity to acid flow, demonstrating its potential to improve injectivity and long-term storage reliability in CO₂ reservoirs.