The Study of The Sealing Performance of Fibrous-Laden Drilling Fluid Over Simulated Lost Zone Under Overbalanced Pressure Conditions

Numerous studies have examined the sealing capabilities of fibrous-amended drilling fluid by measuring filtrate volumes and assessing how well the fibrous plant fragments close fissures. Limited studies have been conducted on the mechanical strength of these materials during the sealing process and their response to plastering pressure. Therefore, this study addressed this gap by providing new data on the relationship between the mechanical strength of fibres and the operating pressure of drilling muds, specifically in preventing lost circulation. The study was carried out using a new experimental methodology involving a high-precision universal tensile machine, which accurately measured the performance of plant fragments in the sealing varying diameters of simulated fractures. Furthermore, the simulated fractures with sizes commonly observed in the field were created to mimic real lost circulation scenarios. The sealing pressure of each fibrous-laden drilling fluid were also observed. The results showed that drilling muds without fibrous additives failed to prevent continued circulation loss, as it lacks the structural integrity necessary for forming a solid muds cake and inhibits infiltration. In contrast, adding plant fragments to drilling muds enables the formation of robust muds cake structures, effectively mitigating drilling fluid losses.