Abstract The huge reserves of Eagle Ford shale gas condensate reservoirs have drawn great attention. The well productivity analysis indicates that the leading Eagle Ford is in reservoir decline stage. Condensate banking effect induces severer adverse effect on ultra-low permeability reservoirs and shale gas production than conventional reservoirs. The objective of this paper is to investigate the effect of CO2 huff-n-puff injection on mitigating condensate accumulation surrounding the induced fractures. The nano-pore confinement effect on condensate and gas production performance is considered. The nano-meter scale of shale condensate plays exhibit different phase behavior than conventional condensate reservoirs. The influence of nano-pore confinement on liquid phase behavior in shales is similar to adding CO2 in admixture with reservoir fluids, which acts to suppress the phase envelope. The interaction of CO2 injection with reservoir oil at molecular scale was discussed. Two scenarios including a lean gas condensate and rich gas condensate were compared in order to study the CO2 huff-n-puff performance with different reservoir fluids. The simulation results indicated that CO2 is more favorable in improving the rich condensate recovery. Removal of condensate accumulation in rich condensate Eagle Ford shale reservoirs by CO2 huff-n-puff injection results in substantial recovery increment in comparison with the pressure depletion scheme. This paper focuses on studying the influences of nano-pore walls on CO2 injection phase behavior in shale gas-condensate reservoirs.

中文翻译：

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使用数值模拟研究使用具有纳米孔效应的循环 CO 2 注入方法提高 Eagle Ford 页岩气凝析油井采收率

摘要 伊格尔福特页岩气凝析气藏的巨大储量备受关注。井产能分析表明，领先的Eagle Ford处于储层递减阶段。凝析油淤积效应对超低渗透储层和页岩气生产的不利影响比常规储层更严重。本文的目的是研究 CO2 huff-n-puff 注入对减轻诱导裂缝周围凝析油积聚的影响。考虑了纳米孔限制对凝析油和产气性能的影响。纳米级的页岩凝析油储层表现出与常规凝析油储层不同的相行为。纳米孔隙限制对页岩液相行为的影响类似于在与储层流体的混合物中添加 CO2，其作用是抑制相位包络。在分子尺度上讨论了 CO2 注入与储层油的相互作用。为了研究不同储层流体的 CO2 huff-n-puff 性能，比较了包括贫气凝析油和富气凝析油在内的两种情况。模拟结果表明，CO2 更有利于提高富凝水回收率。与压力消耗方案相比，通过 CO2 huff-n-puff 注入去除富凝析油 Eagle Ford 页岩储层中的凝析油聚集导致显着的采收率增量。本文重点研究了纳米孔隙壁对页岩气-凝析油藏CO2注入相行为的影响。在分子尺度上讨论了 CO2 注入与储层油的相互作用。为了研究不同储层流体的 CO2 huff-n-puff 性能，比较了包括贫气凝析油和富气凝析油在内的两种情况。模拟结果表明，CO2 更有利于提高富凝水回收率。与压力消耗方案相比，通过 CO2 huff-n-puff 注入去除富凝析油 Eagle Ford 页岩储层中的凝析油聚集导致显着的采收率增量。本文重点研究了纳米孔隙壁对页岩气-凝析油藏CO2注入相行为的影响。在分子尺度上讨论了 CO2 注入与储层油的相互作用。为了研究不同储层流体的 CO2 huff-n-puff 性能，比较了包括贫气凝析油和富气凝析油在内的两种情况。模拟结果表明，CO2 更有利于提高富凝水回收率。与压力消耗方案相比，通过 CO2 huff-n-puff 注入去除富凝析油 Eagle Ford 页岩储层中的凝析油聚集导致显着的采收率增量。本文重点研究了纳米孔隙壁对页岩气-凝析油藏CO2注入相行为的影响。模拟结果表明，CO2 更有利于提高富凝水回收率。与压力消耗方案相比，通过 CO2 huff-n-puff 注入去除富凝析油 Eagle Ford 页岩储层中的凝析油聚集导致显着的采收率增量。本文重点研究了纳米孔隙壁对页岩气-凝析油藏CO2注入相行为的影响。模拟结果表明，CO2 更有利于提高富凝水回收率。与压力消耗方案相比，通过 CO2 huff-n-puff 注入去除富凝析油 Eagle Ford 页岩储层中的凝析油聚集导致显着的采收率增量。本文重点研究了纳米孔隙壁对页岩气-凝析油藏CO2注入相行为的影响。