深层-超深层缝洞型漏失通道堵漏浆驻留机制与材料协同设计：CFD-DEM研究进展

Retention mechanisms and collaborative material design of lost-circulation-control slurry in deep and ultra-deep fractured-vuggy loss channels： A CFD-DEM review

摘要:

深层-超深层缝洞型漏失通道具有开度突变、粗糙壁面、局部扩容和远端强连通等特征，堵漏材料易发生入口封门、深部耗散或封堵层冲刷失稳。为阐明堵漏浆由输运向驻留转变的控制机制，重点评述近十年CFD?DEM及相关颗粒尺度模拟，比较计算域、网格尺度、时间步长、边界条件、接触模型、流体本构与验证方法，并将定量结果用于材料协同设计分析。结果表明：在特定粗糙裂缝模型中，当颗粒直径/裂缝宽度（d/W）=0.4、壁面摩擦系数为0.5、入口速度为0.1 m/s时，颗粒体积分数8%，在3 s内未形成封堵，而10%和20%分别在2.6和2.2 s形成封堵；另一三维裂缝研究得到粒径0.50~0.67 W、浓度8%、载液黏度50 mPa·s及壁面摩擦系数0.7~0.9的较优组合。针对2~5 mm裂缝的形状记忆颗粒模拟中，裂缝由3 mm×2 mm增至5 mm×4 mm时，封堵时间由0.11 s增至0.25 s、漏失率由4.6%增至12.3%。绝对架桥加量与补差紧密堆积设计使3组对比体系的承压能力提高100%~229%，累计漏失量降低31%~38%，材料用量降低28%~76%。上述阈值均受通道几何、材料形状和边界条件约束，不能作为通用配方。基于此，提出以通道参数化、几何级配、载液流变、高温功能保持和多尺度验证为主线的协同设计流程，为堵漏材料由经验复配向可计算、可验证设计转变提供依据。

Abstract:

Deep and ultra-deep fractured-vuggy loss channels are characterized by abrupt aperture variation， rough walls， local expansion and strong distal connectivity， which may cause premature entrance sealing， deep material loss or erosion-induced failure of the plugging zone. To clarify the governing mechanism for the transition of lost-circulation-control slurry from transportation to retention，this review examines particle-scale CFD-DEM and related simulations published mainly during the past decade， with emphasis on computational domains， mesh size， time steps， boundary conditions， contact laws， fluid constitutive models and validation， and quantitative results are adopted for synergistic material design analysis.The results show that in a specific rough-fracture model with a ratio of particle diameter and fracture width （d/W）=0.4， a wall-friction coefficient of 0.5 and an inlet velocity of 0.1 m/s， an 8% particle volume fraction did not seal within 3 s， whereas 10% and 20% sealed at 2.6 and 2.2 s， respectively. A separate three-dimensional fracture study identified a model-specific favorable combination of particle size of 0.50~0.67 W， concentration of 8%， carrier-fluid viscosity of 50 mPa·s and wall-friction coefficient of 0.7~0.9. In a shape-memory-particle simulation for 2~5 mm fractures， increasing the inlet-outlet dimensions from 3 mm×2 mm to 5 mm×4 mm， increased sealing time from 0.11s to 0.25 s and loss ratio from 4.6% to 12.3%. A design combining absolute bridging dosage with gap-filling dense packing increased pressure-bearing capacity by 100%~229%， while reduced cumulative loss by 31%~38% and material consumption by 28%~76% in three comparative cases. These thresholds are conditional on channel geometry， particle shape and boundary settings and should not be treated as universal formulations. Based on this， a collaborative design workflow integrating channel parameterization， geometric gradation， carrier-fluid rheology， high-temperature functional retention and multiscale validation is therefore proposed， which provides support for the lost-circulation-control material transportation from empirical compounding toward computable and verifiable design.