Lost Circulation Material Implementation Strategies on Fluid Loss Remediation and Formation Damage Control

Abstract The design of lost circulation remediation strategies is complicated in naturally fractured reservoirs. It has been a great challenge for engineers to balance between fracture plugging and formation damage. In this study, experimental investigations and statistical analysis were conducted to explore the effects of LCM implementation strategies in lost circulation remediation and formation damage control. Different combinations of granular and fibrous LCMs were tested in a permeability plugging apparatus with slotted discs. When LCM particles accumulated at the slots and formed a low-pressure-bearing plug, the injecting pressure was held constant to enable further establishment of the plug through filtration. The effects of LCM soaking time, soaking pressure, and injection rate on plug breaking pressure and total fluid loss volume were investigated. Full factorial experimental design and analysis of variance (ANOVA) were performed to study the statistical significance of each parameter. For granular LCM mixtures, the soaking pressure and time did not have a significant impact on the ultimate plug breaking pressure and the cumulative fluid loss. For mixtures blended with fibrous LCMs, longer soaking time contributed to increasing the plug breaking pressure and reducing fluid loss. A low LCM pill injection rate reduced the fluid loss volume comparing to a high injection rate upon the establishment of an effective seal. Incorporating fibrous LCMs enhanced the slot sealing effects since the dehydrated mud plug formed not only at the fracture mouth, but also inside the fracture. This prevented the plug from being washed down when drilling resumes. The results and conclusions from this study provide new insights on the identification of optimal LCM implementation strategy with better formation damage control.