Optimizing Sustainable Polysaccharide-Based Drilling Muds with Red Mud for Geothermal Applications

Abstract Geothermal drilling demands specialized drilling fluids to handle extreme high temperature high pressure (HTHP) environments. Conventional water-based muds (WBMs) utilize mined minerals like bentonite with toxic polymers, causing environmental harm. Produced water (PW) is an abundant byproduct of oil/gas production posing disposal issues. Red mud (RM) is an alkaline waste from aluminum refining that is landfilled. This research investigates formulating sustainable PW-based muds (PWBMs) with RM for geothermal drilling. RM was characterized and hot-rolled PWBMs were optimized evaluating rheology, fluid loss, and solids suspension capacity at HTHP conditions. PW displayed high salinity up to 224,937 ppm and hardness up to 15,932 ppm, presenting technical barriers including clay swelling, scale potential, and incompatible fluid chemistry. However, engineered PWBM formulations resolved these issues. Increasing polysaccharide concentrations enhanced yield point, gel strength, and low-shear rate viscosity of PWBMs. At 8 ppg polysaccharide dose, saline PWBMs achieved viscosity surpassing freshwater WBMs. RM inclusion further reduced fluid loss by 50% versus conventional calcite mud system (CCMS). PWBMs also demonstrated superior sag resistance, with 8 ppg polysaccharide enabling sag factors as low as 0.5-0.53 in vertical and inclined orientations. This pioneering research successfully developed sustainable PWBMs leveraging two waste streams. RM improved filtration control as a benign substitute for lignosulfonates. Demonstrated technical performance resolves produced water reuse limitations in geothermal drilling. Optimized PWBMs met drilling fluid specifications while utilizing only non-potable resources. This eliminates sourcing, water, energy for conventional WBM components with associated environmental and economic savings. Integrating green design principals, this study provides a sustainable technology pathway significantly reducing impacts for geothermal well construction. Field validation is recommended to facilitate commercial adoption. Overall, red mud is a promising new option for geothermal drilling fluid additives. It is more environmentally friendly, and it can improve the performance of drilling fluids under HPHT conditions. The possibility does exist for the red mud additive to be used as an inert additive to optimize various drilling fluid properties.