Evaluation and remediation techniques for barite sagging: A review

Heavy-weight materials such as barite (BaSO₄) is used in mud formulations to increase density. In deeper formations where a higher hydrostatic pressure of the mud column is required to overcome the pore pressure, the use of heavy-weight mud systems is indispensable. Unfortunately, these heavy-weight particles tend to settle under both static and dynamic conditions, resulting in density variations, a phenomenon known as sagging or barite sagging due to the dependence on barite as a heavy-weight agent. There is extensive knowledge in the literature on the mechanism and remediation of sag. The current work is a critical review of research conducted on this subject. The purpose is to identify knowledge gaps and improve future developments through the compilation of recommended solutions and best practices. Several important findings have been made from this review. It was found that sagging is more common in oil-based mud compared to other mud formulations. Additionally, sag was found to be more of a dynamic challenge where the deposition of particles occurs most commonly in 60–70 ° inclined wellbores. The development of mud systems using stabilizers such as clays, polymers, and other agents, the use of unconventional weighting systems such as micronized particles and the combination of weighting materials have been proposed as plausible mitigation options. We recommend the deployment of machine learning algorithms for real-time sag evaluation. The implementation of unconventional weighting systems in field mud formulations could also help to mitigate sagging.