Download the document - Global CCS Institute

The third variation of Figure 4.48 repeats the second variation but for a 1 km water column. With theexception of data in Figure 4.55, where the western edge of the target is fixed and the western edgevaries, responses show greater variation that for the equivalent 100 m water column cases. The ability todelineate a target’s extent depends on the survey configuration. If surveys straddle the injection well, andthe CO 2 plume expands symmetrically around that well, then mCSEM can only delineate targets whentheir length is greater than 4 km (Figure 4.56). However, if surveys are positioned some distance fromthe injection well so that in plume moves towards the transmitter, as in Figure 4.57, then as with a 100 mwater column in Figure 4.53, variations in target size can clearly be distinguished. The advantage of adeeper water column is that more confidence can be ascribed to an interpretation because all measuredcomponents show similar variation.| 107