FIELD DATA EXAMPLES

Anisotropic tomography was performed using a field data set. This data set was acquired jointly by Amoco and Stanford University at the Gulf Coast, on shore, in Southeast Texas. The overall survey geometry is illustrated in Figure , and it is similar to the one used in the synthetic example of 2-D inversion. More details about the site and geometry are found in Harris et al. (1990b).

 

geometry
Figure 9 Overall survey geometry illustrating the shooting pattern. Receivers are spaced at dr = 10 ft between 2688 and 3996 ft Sources are spaced at ds = 10 ft interval in primary target zone and ds = 20 ft. above and bellow the target zone.

Nearly 5000 P-wave first arrival times were picked form the data. In general, we found that the traveltimes corresponding to the near horizontal rays (near offsets) were more difficult to pick than those at far offsets.