资源环境科技发展态势分析平台

Seismic monitoring of injected CO₂ plumes in fractured storage reservoirs relies on accurate knowledge of the physical mechansims governing elastic wave propagation, as described by appropriate, validated rock physics models. We measured laboratory ultrasonic velocity and attenuation of P‐ and S‐waves, and electrical resistivity, of a synthetic fractured sandstone with obliquely aligned (penny‐shaped) fractures, undergoing a brine‐CO₂ flow‐through test at simulated reservoir pressure and temperature. Our results show systematic differences in the dependence of velocity and attenuation on fluid saturation between imbibition and drainage episodes, which we attribute to uniform and patchy fluid distributions, respectively, and the relative permeability of CO₂ and brine in the rock. This behaviour is consistent with predictions from a multi‐fluid rock physics model, facilitating the identification of the dispersive mechanisms associated with wave induced fluid flow in fractured systems at seismic scales.