Compressional waves are sensitive to the type of pore fluid within rocks, but shear waves are only slightly affected by changes in fluid type. This suggests that a comparison of compressional- and shear-wave seismic data recorded over a prospect may allow an interpreter to discriminate between gas-related anomalies and those related to lithology. This case study documents that where a compressional-wave 'bright spot' or other direct hydrocarbon indicator is present, such a comparison can be used to verify the presence of gas. In practice, the technique can only be used for a qualitative evaluation. However, future improvement of shear-wave data quality may enable the use of more quantitative methods as well.