A petroelastic-based feasibility study of monitoring pressure depletion in a UKCS gas reservoir

The possibility of using 4D seismic for monitoring pressure depletion in the gas-bearing sands of the Rotliegend Group, Southern Gas Basin, is assessed. On the basis of the rock physics work done, the results suggest that production induced changes to unfractured sands are unlikely to be observed. However, the presence of clusters of fractures can render the 4D signature visible. A favorable response is especially likely for certain distinct facies distributions. The strongest signature of depletion occurs beneath the producing zone, and is due to a combination of reflectivity change and event time displacement.