Abstract When drilling through naturally fractured reservoirs, the remediation of drill-in fluid loss needs to be designed by taking both fracture plugging and formation damage into account. Lost circulation materials (LCMs) should be implemented efficiently to minimize the solid-laden fluid invasion into the fractures during the development of fracture plugs. This study investigated the effects of three LCM deployment factors: injection rate, soaking time, and soaking pressure, on the total fluid invasion volume and plug breaking pressure. Full factorial experimental design and statistical analysis were conducted to study the statistical significance of each factor. Scanning Electron Microscope (SEM) and Micro Computed Tomography (MicroCT) were applied to visualize the plug structures for the understanding of the soaking effects. Different combinations of LCMs were tested in a permeability plugging apparatus with a slotted disk. For granular LCM mixtures, the soaking pressure and time did not have a significant impact on total fluid invasion volume or ultimate plug breaking pressure. For mixtures blended with fibrous LCMs, longer soaking time contributed to reducing fluid loss and increasing plug breaking pressure. A lower LCM pill injection rate led to less fluid invasion upon the establishment of an effective seal. The SEM and MicroCT images indicated that a longer soaking time could lead to a less porous and strengthened plug structure. The results and conclusions from this study provide new insights into the identification of optimal LCM implementation scheme with better formation damage control.

中文翻译：

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裂缝封堵LCM浸渍工艺流体损失修复和地层损害控制研究

摘要 钻探天然裂缝性储层时，需要兼顾裂缝封堵和地层损伤设计，对钻井液漏失进行修复。应有效实施堵漏材料 (LCM)，以最大程度地减少裂缝塞开发过程中载有固体的流体侵入裂缝。本研究调查了三个 LCM 部署因素：注入速率、浸泡时间和浸泡压力，对总流体侵入体积和塞子破裂压力的影响。进行全析因实验设计和统计分析，研究各因素的统计显着性。应用扫描电子显微镜 (SEM) 和显微计算机断层扫描 (MicroCT) 来可视化插塞结构，以了解浸泡效果。LCM 的不同组合在带槽盘的渗透性封堵装置中进行了测试。对于粒状 LCM 混合物，浸泡压力和时间对总流体侵入量或极限塞破裂压力没有显着影响。对于与纤维状 LCM 混合的混合物，较长的浸泡时间有助于减少流体损失并增加塞子破裂压力。在建立有效密封后，较低的 LCM 丸剂注射率导致较少的流体侵入。SEM 和 MicroCT 图像表明，较长的浸泡时间可能会导致更少的孔隙和加强的塞结构。本研究的结果和结论为识别具有更好地层损伤控制的最佳 LCM 实施方案提供了新的见解。