The Effect of Thixotropic Additive on Cement Slurry Properties to Overcome Lost Circulation

Lost circulation during drilling poses serious operational challenges, including increased costs, non-productive time, environmental hazards, and safety risks. A viable mitigation strategy involves the use of specially formulated plugging slurries capable of sealing loss zones effectively. This study explores the role of thixotropic additives in enhancing the performance of cement slurries for such applications. Cement slurries were tested with thixotropic additive concentrations of 0.10%, 0.15%, and 0.18% by weight of cement to evaluate their impact on rheology, gel strength, and compressive strength. The results demonstrate that thixotropic additives significantly improve early gelation and static gel strength, essential for bridging fractures and reducing fluid loss. Formula 2(0.15%) was identified as the optimal concentration, offering a balanced improvement in structure-building capability and pumpability. Although higher concentrations, such as Formula 3 (0.18%), provide faster setting and higher gel strength, they may compromise pumpability and slightly reduce ultimate compressive strength. Nevertheless, all tested formulas maintained compliance with API standards and exhibited acceptable fluid loss and free water values. These findings support the application of thixotropic cement systems as an effective solution for lost circulation control in challenging wellbore conditions.