Local capillary trapping (LCT) is the trapping of CO₂ by local capillary barriers. It occurs during buoyancy-driven migration of bulk phase CO₂ within a saline aquifer exhibiting spatially varying properties (permeability and capillary entry pressure). The benefit of LCT, in the context of CO₂ sequestration, is that local capillary trapped CO₂ is not susceptible to leakage through failed seals. However, it is unclear how the petrophsyical/geological properties and flow dynamics influence LCT. Thus, the objective of this work is to evaluate the degree to which potential local capillary traps are filled and quantify the extent of immobilization persisting after loss of seal integrity. This paper presents a systematic and thorough study of the influential parameters of LCT. Fine-scale capillary pressure fields are generated by using geostatistical permeability realizations and applying the Leverett j-function. Multiple factors are examined, including injection rate, anisotropy, formation dip, aquifer types, residual gas saturation, and capillary hysteresis. Leakage representative of wellbore failure is simulated, and LCT after leakage is evaluated and compared to other trapping mechanisms. The results show that local capillary traps in the near-well region can be fully filled during injection. Moreover, they remain filled after post-injection buoyancy-driven flow ends. The filling efficiency of local capillary traps increases with the decrease in gravity number (ratio of buoyant force over viscous force). As a result, maximizing LCT in carbon sequestration in porous reservoirs may be achievable with the implementation of appropriate injection strategies.

局部毛细管捕集（LCT）是通过局部毛细管屏障捕集CO ₂。它发生在浮力驱动的散装相CO ₂在盐水层中的迁移过程中，表现出空间变化的特性（渗透率和毛细管进入压力）。在螯合CO ₂的情况下，LCT的好处是局部毛细管捕获了CO ₂不易因密封失效而泄漏。但是，尚不清楚岩石/地质特性和流动动力学如何影响LCT。因此，这项工作的目的是评估潜在的局部毛细血管陷阱被填充的程度，并量化失去密封完整性后固定的持续程度。本文对LCT的影响参数进行了系统而全面的研究。精细尺度的毛细管压力场是通过使用地统计渗透率实现并应用Leverett j函数生成的。检查了多个因素，包括注入速率，各向异性，地层倾角，含水层类型，残余气体饱和度和毛细管滞后。模拟了代表井眼泄漏的泄漏量，并评估了泄漏后的LCT并将其与其他陷井机制进行了比较。结果表明，在注入过程中，近井区域中的局部毛细管阱可以被完全充满。此外，在注入后浮力驱动的流结束后，它们仍保持填充状态。局部毛细管捕集器的填充效率随重力数的减少（浮力与粘性力之比）的增加而增加。因此，通过实施适当的注入策略，可以实现最大化LCT的碳固存能力。