For unconventional reservoirs, the effect of adsorption on phase equilibrium cannot be neglected because the process occurs in extremely tight porous media. This work focuses on the adsorption prediction of multicomponent mixture systems in tight porous media with the oil–gas-adsorption three-phase equilibrium model to a gas sample in the literature. The revisited vacancy solution model of adsorption by Bhatia and Ding is introduced to study the adsorption behaviors of the mixture. The gas and adsorbed phases are assumed to be the solutions of adsorbates with a hypothetical solvent called “vacancy”, and the vacancy is treated as an additional component engaged in the phase equilibrium in this theory. Instead of using parameters extracted from the multicomponent adsorption data, this method takes advantage because it accurately predicts the gas mixture adsorption equilibrium with consideration of non-ideal behavior in the adsorbed phase from pure gas adsorption isotherms over wide ranges of conditions, which could be efficient in terms of cost and time. It can explain the competitive adsorption phenomenon, which is proven during the adsorption process of the gas mixture. The experimental data in the literature of CH₄–C₂H₆ binary gas mixtures of different compositions with a pressure ranging from 0 to 125 bar under the temperatures of 40, 50, and 60 °C are restudied in this work. The prediction results are compared to two other methods, including the extended Langmuir model and the multicomponent potential theory. This method shows an improved precision with less than 5% mean absolute percentage error in all cases. In addition to predications of desorption for the depletion process, the vacancy solution model has the potential in future work to give simulations for other production operations, such as CO₂ or N₂ injection for the displacement of hydrocarbons in shales.

中文翻译：

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油气吸附三相空位溶质模型预测致密多孔介质中多组分气体混合物的吸附等温线

对于非常规油藏，吸附对相平衡的影响不可忽略，因为该过程发生在非常紧密的多孔介质中。这项工作着重于多组分​​混合物系统在致密多孔介质中的吸附预测，并结合文献中的油气吸附三相平衡模型对气体样品进行了预测。引入了Bhatia和Ding的吸附空位溶液模型，研究了混合物的吸附行为。假设气相和吸附相是被吸附物与假设的溶剂（称为“空位”）的溶液，并且在该理论中，空位被视为参与相平衡的其他组分。而不是使用从多组分吸附数据中提取的参数，该方法之所以具有优势，是因为它可以在宽范围的条件下，根据纯气体吸附等温线准确地预测吸附相中的非理想行为，从而准确预测气体混合物的吸附平衡，这在成本和时间方面都是有效的。它可以解释竞争性吸附现象，这种现象在混合气体的吸附过程中得到了证明。CH文献中的实验数据在这项工作中，对在40、50和60°C下压力范围为0至125 bar的_{4 –} C ₂ H ₆二元混合气体进行了重新研究。将预测结果与其他两种方法进行了比较，包括扩展的Langmuir模型和多组分势理论。在所有情况下，该方法均显示出提高的精度，平均绝对百分比误差小于5％。除了对枯竭过程进行解吸的预测外，空缺解决方案模型还具有在将来的工作中为其他生产操作（例如注入CO ₂或N ₂注入以置换页岩中的碳氢化合物）进行模拟的潜力。