Experimental Study on Microbial-Induced Calcium Carbonate Precipitation Repairing Fractured Rock under Different Temperatures

Microbial-induced calcium carbonate precipitation (MICP) technology mainly uses carbonates produced by the reaction of microbial activities to repair rocks and soils. Temperature influences microbial metabolism and the kinetics of chemical reactions. In this study, microbial repair experiments on fractured sandstone under different temperatures are carried out. The repair effects are tested with nuclear magnetic resonance (NMR), an X-ray automatic diffractometer (XRD), uniaxial compressive strength (UCS), and a scanning electron microscope (SEM) test. The influence of the temperature on the restorative effects of MICP was discussed. The results show that the repair effect of the Sporosarcina pasteurii is significantly better as the temperature increases. When the temperature reaches 33 °C, the porosity and permeability of fractured sandstone can be reduced by 55.174% and 98.761%, respectively. The average uniaxial compressive strength can be restored to 6.24 MPa. The repair effect gradually weakens with the increase in temperature. However, the Sporosarcina pasteurii can still maintain relatively good biological activity at temperatures from 33 °C to 39 °C. The main form of CaCO 3 produced in the process of MICP is calcite. It can fill in the rock pores, and result in reducing the size and number of large pores and improving the impermeability and strength of fractured yellow sandstone.