The interpretation of time-lapse seismic monitoring of CO₂ sequestration has typically focused on mapping the saturation and pressure changes. However, elastic wave velocity and associated seismic attribute variation also depend on the poroelastic response to CO₂ injection. In this study, we investigated the impact of effective stress changes on elastic wave velocity responses during CO₂ storage within a carbonate reef of the Michigan basin. The geomechanical multiphase flow modeling combined with the experimental measurements were used to investigate the impact of effective stress on changes in velocities. We measured the ultrasonic compressional (V_p) and shear (V_s) wave velocities in cores acquired from the carbonate formations under different stress-pressure scenarios. Experimental scenarios were applied by changing the effective stress and pore pressure conditions simulating injection into the depleted reservoir. Experimental results show that incorporating stress changes of injection avoids overestimation of changes in velocities due to considering only pore pressure effects. Coupled multiphase flow – geomechanical simulations were performed to assess stress and saturation change during CO₂ injection. We discussed expected changes in elastic wave velocities using combined simulation results with experimental ones. The simulation results show that both effective stress and saturation changes contribute to changes in velocities in the main reservoir. Effective stress is the dominant parameter that contributes to changes in velocities in the upper formations. Results of this work show that quantifying the poroelastic effect of stress on elastic wave velocities changes can lead to a better interpretation of changes in seismic attributes during CO₂ injection. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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量化有效应力对由于二氧化碳注入枯竭碳酸盐礁而引起的弹性波速度变化的影响

_{对 CO 2}封存的延时地震监测的解释通常集中在绘制饱和度和压力变化图上。然而，弹性波速度和相关的地震属性变化也取决于对 CO ₂注入的孔隙弹性响应。在这项研究中，我们研究了在密歇根盆地碳酸盐礁内CO ₂储存期间有效应力变化对弹性波速度响应的影响。地质力学多相流模型与实验测量相结合，用于研究有效应力对速度变化的影响。我们测量了超声压缩 ( V _p ) 和剪切 ( V _s) 在不同应力-压力情景下从碳酸盐地层获得的岩心中的波速。通过改变模拟注入枯竭储层的有效应力和孔隙压力条件来应用实验场景。实验结果表明，结合注入的应力变化避免了由于仅考虑孔隙压力效应而高估速度变化。耦合多相流 - 进行地质力学模拟以评估 CO _{2期间的应力和饱和度变化}注射。我们使用结合模拟结果和实验结果讨论了弹性波速度的预期变化。模拟结果表明，有效应力和饱和度变化都有助于主储层中的速度变化。有效应力是影响上部地层速度变化的主要参数。这项工作的结果表明，量化应力对弹性波速度变化的孔隙弹性效应可以更好地解释 CO ₂注入过程中地震属性的变化。© 2021 化学工业协会和 John Wiley & Sons, Ltd.