Microbially Induced Calcite Precipitation (MICP) Improved Drilling Fluid Optimization for Gravel Stratum

During the exploration of the gravel stratum, incidents such as wellbore leakage, stuck drilling, and unstable wellbore walls frequently occur. These issues lead to diminished drilling efficiency and prolonged construction timelines, ultimately adversely affecting the core recovery rate, resulting in a significant waste of manpower and material resources. To address the issue of hole collapse during drilling, the microbially induced calcite carbonate precipitation (MICP) technique was employed to enhance the properties of bentonite mud drilling fluids. This study analyzed the effects of three factors, i.e., bentonite, biological solution, and barite powder, on the bentonite mud bio-cementation effectiveness through an orthogonal experiment and response surface methodology (RSM). The biological mechanism was examined using scanning electron microscopy (SEM). The experimental results indicated that optimal formulation was achieved when the mass fraction of bentonite was 13.96%, the biological solution comprised 0.6% xanthan gum and 0.4% carboxymethyl cellulose, and the mass fraction of barite was 25%. This research explores the application potential of MICP in enhancing the rheological properties of bentonite mud drilling fluids, which provides new insights and technical references for optimizing their performance.