Elastic (seismic) wave stimulation is considered one of the unconventional enhanced oil recovery (EOR) methods. Increasing water quantity in the high permeability layer of a mature oil reservoir is highly challenging and can significantly decrease the ultimate recovery due to the reservoir heterogeneity. Using seismic waves can be considered low-cost, environmentally friendly, and illuminates the entire reservoir size compared to conventional EOR methods. A numerical model is developed by extending the Quintal approach for seismic attenuation due to wave-induced fluid flow (WIFF) to incorporate capillary pressure in partially saturated porous media and shift undrained boundary conditions to exclude external flow stress for drained boundary conditions. Therefore, the fluid distribution due to the capillary effect makes the developed finite element method (FEM) u-p model more widely applicable for oil recovery in mature reservoirs. A two-layer partially saturated media was subjected to compressive seismic stress at low frequency (3 Hz). The results indicated that the vertical displacement gradients of the bottom and upper layers decline with excitation time for both fully and partially saturated media. On the other hand, partially saturated pore pressure gradients of both the upper and bottom layers have higher amplitudes with excitation time than fully saturated pore pressure gradients due to the influence of capillar pressure. The cumulative crossflow oil volume for 180 days of continuous stimulation was 1176 bbl, 1032 bbl, and 648 bbl in low permeability layers: 200 md, 100 md, and 50 md, respectively. Therefore, the developed model has the potential for field-scale EOR applications. The study also suggests coupling elastic EOR with CO2 flooding to recover more oil due to increasing fluid mobility and relative permeability to oil in low-permeability reservoirs or tight formations.

中文翻译：

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弹性波的耦合位移-压力模型在成熟砂岩储层中诱导流体流动


弹性（地震）波刺激被认为是非常规的提高石油采收率 （EOR） 方法之一。增加成熟油藏高渗透层中的水量极具挑战性，并且由于油藏非均质性，可能会显著降低最终采收率。与传统的 EOR 方法相比，使用地震波可以被认为是低成本、环保的，并且可以照亮整个储层大小。通过扩展波诱导流体流动 （WIFF） 引起的地震衰减的 Quintal 方法，将毛细管压力纳入部分饱和的多孔介质中，并移动不排水边界条件以排除排水边界条件的外部流动应力，从而开发了一个数值模型。因此，毛细效应引起的流体分布使得所开发的有限元法 （FEM） u-p 模型更广泛地适用于成熟油藏的采油。两层部分饱和介质承受低频 （3 Hz） 的压缩地震应力。结果表明，对于完全饱和和部分饱和介质，底层和上层的垂直位移梯度都随着激发时间而下降。另一方面，由于毛细管压力的影响，上层和底层的部分饱和孔隙压力梯度在激发时间内的振幅高于完全饱和的孔隙压力梯度。在低渗透层中，连续增产 180 天的累积错流油体积分别为 1176 bbl、1032 bbl 和 648 bbl：分别为 200 md、100 md 和 50 md。因此，开发的模型具有田间规模 EOR 应用的潜力。 该研究还建议将弹性 EOR 与 CO2 驱相结合，以回收更多的石油，因为在低渗透性储层或致密地层中，流体流动性和对石油的相对渗透性增加。