Thin Stacked Layers of CO2: Implications for Seismic Monitoring

Time-lapse seismic data for reservoir monitoring has traditionally been interpreted mainly using amplitude-based attributes such as normalised root-mean-square (NRMS). Amplitudes can however be affected by constructive and destructive interference where thin beds are involved. We demonstrate the pitfalls of traditional amplitude-based interpretation in the case of time-lapse seismic monitoring of thin stacked layers of CO2 using a wedge model. We apply our analysis to data from a CO2 storage site. Our results imply that if only traditional amplitude-based 4D attributes are employed, CO2 plume volume estimates from seismic monitoring can be significantly inaccurate. In addition, these inaccurate estimates can lead to misinterpretation of patterns of CO2 plume development over time.