Abstract Developed fractures are important storage space and permeable channel in hydrocarbon reservoirs. However, they will lead to drill-in fluid loss and induce severe formation damage. Fracture plugging with granular lost circulation material (LCM) is most commonly used to control drill-in fluid loss. To our best knowledge, traditional research about LCM bridging mainly performed by the trial-and-error method. However, the behavior of granular LCM migration and bridging in a fracture on mesoscale is still unclear. In this paper, the coupled CFD-DEM approach is used to simulate the flow of granular LCM in a vertical fracture. The effects of particle size distribution (PSD) and concentration on the fracture plugging process are studied by a series of controlled numerical experiments. The research suggests that: (1) When Wf/D50<1.5, the critical particle concentration softly increases with particle size distribution (PSD), but the area with Wf/D50>1.5 the critical particle concentration sharply increases with PSD. (2) The plugging process can be divided into two distinct stages from pressure drop rate: particle bridging and particle accumulation. (3) The drill-in fluid loss rate is affected by the plugging process, the structure of plugging zone and PSD.

中文翻译：

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裂缝中颗粒 LCM 桥接的耦合 CFD-DEM 模拟

摘要 裂缝发育是油气藏重要的储集空间和渗透通道。然而，它们会导致钻井液流失并导致严重的地层损坏。用粒状堵漏材料 (LCM) 封堵裂缝最常用于控制钻井液漏失。据我们所知，关于 LCM 桥接的传统研究主要通过试错法进行。然而，中尺度裂缝中颗粒 LCM 迁移和桥接的行为仍不清楚。在本文中，耦合 CFD-DEM 方法用于模拟颗粒 LCM 在垂直裂缝中的流动。通过一系列受控的数值实验研究了粒度分布（PSD）和浓度对裂缝封堵过程的影响。研究表明：（1）当Wf/D50<1.5时，临界粒子浓度随粒度分布（PSD）缓慢增加，但在 Wf/D50>1.5 的区域，临界粒子浓度随 PSD 急剧增加。(2) 堵漏过程从压降速率上可分为颗粒架桥和颗粒堆积两个阶段。(3) 钻井滤失率受封堵工艺、封堵带结构和PSD的影响。