Case study: Non-Rigid Matching

A Q-Marine survey was acquired for DONG within which 4D differences were identified. Statics were applied in the processing sequence to align both datasets to the correct time. This however caused a movement of data at the chalk reservoir target interval. When a difference cube was taken this movement caused a misalignment of seismic events, and 4D effects were seen above the reservoir. The miss-alignment indicated a possible gas chimney above the reservoir, which was known not to exist.

Non-Rigid Matching was applied to re-align the events, so that any 4D change seen would be due to changes within the reservoir resulting from the gas injection. The lower figure on the right shows the final difference section after Non Rigid Matching, and the residual statics are no longer present. The use of Non-Rigid Matching removed the misalignment caused by the static corrections and allowed the 4D effects caused by the gas injection to be mapped.