An Evaluation of the Combination of Fibers and Granules for Lost Circulation Material Applications

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Summary To counter the issue of lost circulation, several types of lost circulation materials (LCMs), such as granules, fibers, and flakes, have been developed and tested in the laboratory and field. Ample research has suggested that the combination of two or more different LCMs instead of a single type leads to a better overall fracture-plugging capability. However, the design of these LCM combinations is more often aligned toward trial and error in an attempt to discover the best LCM properties rather than an in-depth and systematic engineering design that appropriately captures the physics of the problem. In this paper, a novel coupled computational fluid dynamics-discrete element method (CFD-DEM) numerical model is developed to closely assess the effect of the combination of granules and fiber LCMs for fracture plugging applications. For an effective LCM design, it is vital to take into consideration the innate particle properties of the fibers and granules as they are among the most important parameters in determining if the combination yields an improved plugging effect than if used separately. For this reason, the effects of important LCM properties such as fiber stiffness, granular particle-size distribution, and the concentration of each LCM type in the blend are investigated in a systematic parametric study. Often, due to a lack of information on the loss zone, the extent of the fracture sizes being dealt with remains unclear, and although granular LCMs by themselves portray good plugging capability in small fractures, due to size limitations, they fail to plug the wide fractures. Thus, the focus of this study is on the scenario when the fiber LCMs are the main drivers of the fracture bridging process. With the help of this study, we attempt to demystify the essential fiber and granular particle properties that in synergy would lead to the best fracture-plugging capability.