Abstract Shale barrier distributes widely in heavy oil reservoirs. However, the influence mechanism of shale barrier on heavy oil recovery is still unclear. For this reason, the influence mechanism in physics was first proposed. Then, the influence mechanism in mechanics was concluded from the steam migration velocity decreasing and the heat conduction rate enhancing. Especially, it was obtained by theoretical analysis that shale barrier has a positive effect on heavy oil recovery under the reasobale condition. To validate the influence mechanism, a numerical model containing the shale barrier was established. The numerical results validated the influence mechanism in physics from two aspects of steam chamber shape and migration behaviors of steam and oil. In addition, the numerical results showed that it has the higher cumulative oil volume and the lower residual oil saturation for the heavy oil recovery when considering reasonable distribution of shale barrier, validating the conclusion that shale barrier has a positive effect on heavy oil recovery. Additionally, the reason behind positive effect caused by the shale barrier was analyzed, including the longer production period, the higher steam injection volume and the lower heat loss. Especially, economic feasibility for heavy oil recovery was evaluated by calculating net present value (NPV) and the ratio of the produced energy to the consumed energy. Finally, the parametric analysis was performed to investigate effects of geometric properties of shale barrier on heavy oil recovery, including the barrier location, the barrier length, the barrier thickness and the number of barrier. The results show that: (1) the reasonable distribution of barrier location far away from the injection well is advantageous for the heavy oil recovery; (2) the reasonable increasing of barrier length, thickness and number is beneficial for the heavy oil recovery.

中文翻译：

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基于理论和数值分析的页岩屏障对SAGD稠油采收的影响机制

摘要 页岩屏障在稠油油藏中广泛分布。但页岩屏障对稠油采收率的影响机制尚不清楚。为此，首先提出了物理学中的影响机制。然后，从蒸汽运移速度的降低和热传导率的提高推断了力学上的影响机制。特别是通过理论分析得出，在再平衡条件下，页岩屏障对稠油采收率有积极影响。为了验证影响机制，建立了包含页岩屏障的数值模型。数值结果从蒸汽室形状和蒸汽和油的运移行为两个方面验证了物理学上的影响机制。此外，数值结果表明，考虑合理分布的页岩屏障对稠油采收具有较高的累积油量和较低的残余油饱和度，验证了页岩屏障对稠油采收有积极影响的结论。此外，分析了页岩屏障产生积极影响的原因，包括生产周期更长、注汽量更大、热损失更低。特别是，通过计算净现值 (NPV) 和生产能源与消耗能源的比率来评估重油采收的经济可行性。最后，通过参数分析研究了页岩屏障几何特性对稠油采收率的影响，包括屏障位置、屏障长度、屏障厚度和屏障数量。结果表明：（1）远离注入井的屏障位置合理分布有利于稠油的采收；(2)屏障长度、厚度和数量的合理增加有利于稠油的采收。