We thank Dina Simin for his perceptive reading of our paper (Madiba and McMechan, 2003) in which he detected a well-tie error. As one of us mentioned to him when he first drew this to our attention, we only wished he had been able to read it before it was published! Initially, his comment seemed unlikely to be true, but a query to Larry Mewhort of Husky Energy confirmed the problem and also the source of the discrepancy. This data set was originally provided by Husky and Talisman for a 1995 SEG workshop on imaging in complex structural areas and included auxiliary information on two-way traveltimes to formation tops. Although our results were consistent with these times, we did not realize that the times were referenced to a datum at 431 m below the top of the well; hence the shifted tie. This fact was noted elsewhere in the auxiliary information, so we accept responsibility for the error. Basically, our identification of the Turner Valley was about 0.2 seconds too shallow; the reflection we labeled as Wabamun is really the Turner Valley.

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