Modelling the geoelectric and seismic reservoir response caused by carbon dioxide injection based on multiphase flow simulation: Results from the CO 2SINK project

Abstract

Results from crosshole geoelectric and surface seismic monitoring for geological storage of carbon dioxide (CO 2) were investigated by forward modelling within the framework of the CO 2SINK project. Selected geological and petrophysical parameters reflect the conditions of the CO 2SINK site. CO 2 saturation distributions were derived from multiphase flow modelling, whereas the alteration of geophysical rock properties by CO 2 was obtained from laboratory experiments. Crosshole geoelectric modelling was performed for three electrode combinations and three time-dependent CO 2 migration scenarios with different reservoir permeabilities. The magnitude and alteration of modelled resistances were analyzed in the pre-inversion domain. Time-lapse alterations were observable on the synthetic data, with diverse characteristics dependent on applied electrode configuration. Analysis of the alterations showed the opportunity to differentiate migration scenarios within the constraints of the ambient noise level. The synthetic time-lapse seismic reflection experiment was performed for the anticline used for CO 2 storage. The geological model incorporates the structural framework, as determined from the seismic interpretation, and velocities derived from seismic processing and velocity logs. Common depth point (CDP) processing of synthetic shot gathers of a baseline and repeat experiment provided the data for a difference stack section exhibiting a CO 2 induced time-lapse signature. Interpretation of the signature in conjunction with the underlying CO 2 distribution has shown that lateral extent of the plume may be accurately detected. The vertical plume extent is concealed in the waveform coda and is unlikely to be retrievable from standard seismic processing.