The Trinidad data

The line acquired from the Trinidad region contains data with offsets that extend to 6 km. This 2-D line was acquired in the regional subsurface dip direction. The source-to-receiver spacing ratio is three, and the maximum fold in the data is 90. Because of the large size of offsets acquired, a nonhyperbolic inversion (Alkhalifah, 1997) was used on these data. Also, many wells exist along this line; one near CMP location 1100 and another near CMP 1220, see Figure 4. The gamma-ray measurements from these wells are reliable shale-sand discriminators, and thus can be used to calibrate our results. In a previous paper (Alkhalifah and Rampton, 1997), we showed some sparse $\eta$ estimates from this line. In this study, we have obtained more detailed estimates of $\eta$ in the same region, as well as included detailed estimates from another part of the line, not shown in the earlier paper.