On: “Comparison of P‐ and S‐wave seismic data: A new method for detecting gas reservoirs” by R. A. Ensley (GEOPHYSICS, 49, 1420‐1431, September, 1984).

Ensley’s paper was based on data of the Conoco Shear Wave Group Shoot of 1977–1978; hence, many companies besides Exxon, including my own, have the Putah Sink data he showed. The stacked sections he showed look identical to the Conoco brute stacks furnished to group shoot participants. The brute stacks had no residual statics or stacking velocity corrections. Those of us who have processed S-wave data often have been pleasantly surprised at how much improvement can come from careful application of residual statics and stacking velocity corrections. Our experience shows that it is unwise to interpret stacked S-wave data that have not had benefit of such refinements.