Using time-lapse seismic monitoring to identify trapping mechanisms during CO₂ sequestration

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• 作者：Grace Cairns¹ ; ^{grace.cairns@uk.bp.com} ; Helmut Jakubowicz ^{h.jakubowicz@imperial.ac.uk} ; Lidia Lonergan ^{l.lonergan@imperial.ac.uk} ; Ann Muggeridge ^{a.muggeridge@imperial.ac.uk}
• 关键词：Sequestration ; CO2 ; Monitoring ; Modelling ; Fluid distribution ; Trapping mechanism
• 刊名：International Journal of Greenhouse Gas Control
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：11
• 期：Complete
• 页码：316-325
• 全文大小：1585 K

文摘

We show that it may be possible to distinguish between structurally and capillary trapped CO₂ using time-lapse seismic monitoring of geological CO₂ sequestration. Commercial reservoir simulation software is used to predict CO₂ saturation in a saline aquifer over time. The output is combined with a rock physics model to calculate the elastic and seismic properties of the aquifer. As the seismic response depends on both fluid content and distribution, appropriate end-member fluid-distribution models are used to predict the possible range of seismic responses. We propose that different fluid-distribution models should be used for capillary and structurally trapped CO₂ in a reservoir; the Hill average should be used for high, mobile CO₂ saturations found during structural trapping whilst the Gassmann-Reuss average should be used for low, immobile CO₂ saturations resulting from residual trapping. Far-offset seismic data is used to interpret reflections produced by the different trapping phases and cross-plotting is used to determine the trapping phase. Results indicate that structurally trapped CO₂ can be seismically imaged irrespective of fluid distribution and, importantly, a reflection may be generated off the interface between residually and structurally trapped CO₂.