Geothermal energy represents a renewable and sustainable solution to global energy challenges, offering a pathway to meet energy demands while reducing carbon emissions. The Williston Basin in North Dakota, characterized by extensive sedimentary layers, presently holds significant geothermal potential, with subsurface temperatures ranging from 60°C to 150°C at depths of 2–3 kilometers (Gosnold et al., 2015). However, current geothermal well operations face critical challenges, including high temperatures, pressures, and corrosive environments, which can compromise well integrity. This explores the use of industrial by-products, such as pumice and eggshell powder, in improving the durability and efficiency of geothermal well cement under thermal stress. It highlights the environmental and economic benefits of utilizing waste materials for developing advanced cement technologies in geothermal energy production. The research addresses critical challenges in geothermal well integrity under extreme temperature conditions (150-300°C). Through systematic experimentation and analysis, we evaluated four cement formulations: a control sample and three blends with different pumice/eggshell powder (PMC/ESP) ratios (75%/25%, 50%/50%, and 25%/75%). The optimal PMC/ESP (75%/25%) blend demonstrated exceptional performance, exhibiting a 341% increase in compressive strength (12.96 MPa vs. 2.93 MPa for control) at 300°C, significantly lower porosity (0.53% vs. 13.07%), and enhanced permeability resistance (0.0019 mD vs. 0.01 mD) compared to conventional cement. XRD analysis revealed that this superior performance correlates with reduced C-S-H formation and increased thermal stability through the formation of xenotolite phases. The findings present a novel approach to enhancing geothermal cement stability, offering a sustainable solution for improving well integrity in high-temperature geothermal applications by utilizing industrial by-products such as pumice and eggshell. The optimized cement formulation offers extended well lifespans, reduced maintenance costs, and improved economic viability while addressing environmental concerns associated with traditional cementing practices.

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