Growth kinetics of Bacillus pasteurii in Xanthan gum solid-free drilling fluid at different temperatures

Abstract

During drilling operations, broken strata may contribute to borehole-wall instability. Improving the cementation forces between broken blocks and forming a complete hole-wall are crucial for maintaining hole-wall stability in broken formations. Microbe-induced calcite precipitation technology provides a useful technical approach; however, changes in the temperature of the formation affect microbial growth. Therefore, studying microbial growth in drilling fluid at different temperatures is necessary. We detected the growth of Bacillus pasteurii in Xanthan gum (XG) solid-free drilling fluid at 2 °C intervals from 30 to 50 °C and analyzed its growth kinetics. Kinetics models were constructed to accurately describe the growth of B. pasteurii in XG solid-free drilling fluid at different temperatures. The results show that B. pasteurii grows under various temperature conditions. The logistic model best described the growth of B. pasteurii in XG solid-free drilling fluid at 30–48 °C, while the Gompertz model best described its growth at 50 °C. Moreover, the Arrhenius model best described the influence of temperature on the maximum specific growth rate of B. pasteurii in XG solid-free drilling fluid. These results lay a theoretical foundation and provide a scientific basis for successfully applying microbial solid-free drilling fluid.