Cementing is essential for sealing. Oil wells, especially in those with high pressure and extreme heat, where problems like poor compressive strength and a short cement setting time arise. To overcome such problems, specific solutions are needed; in hostile environments, additives are used to raise the cement slurry's requirements. A range of chemical additives, like silica fume, metakaolin, and hybrid fibers, optimize the quality of the cement slurry when added to the mixture. Silica fume increases strength, lowers permeability, and reduces fluid loss when used with dispersants and fluid reduction agents. Type G cement is made more durable and resistant to corrosion by replacing a portion of the cement with a fraction of metakaolin. The cement slurry is supplemented with hybrid fibers to increase its durability and mechanical qualities. This study aims to show how additives can be utilized to achieve several key characteristics, such as extending the thickening time and providing adequate insulation of the casing from geological formations. To improve the slurry's compressive strength and guarantee adequate insulation and well safety, a number of studies should be conducted. This study addresses the challenge of optimizing oil well cement for high-pressure, high-temperature environments by incorporating supplementary cementitious materials (SCMs) and fibers. The key findings highlight improvements in compressive strength, reduced permeability, and enhanced durability, making the cement mix more resilient in extreme conditions.