Estimation of anisotropy parameters in application to Blackfoot seismic data

Chunyan (Mary) Xiao, John C. Bancroft, R. James Brown

Anisotropy parameters are obtained by anisotropic velocity analysis performed on Blackfoot P-wave reflection-seismic data, in combination with sonic-log data. First, the line was processed with ProMAX seismic data-processing software using a sequence of conventional algorithms without taking anisotropy into account, in order to choose proper analysis points and horizons with confidence. Then, at selected analysis points, we correlated well logs, synthetic data, Blackfoot seismic data, and interpreted formation tops, to obtain the vertical interval velocities. Four seismic intervals were chosen for estimation of Thomsen's anisotropy parameters. The results show that estimated values of and seem reasonable only if the time intervals are larger than about 200 ms. When the lower three layers are combined as one target layer, it exhibits relatively high values of and of about 0.37 and 0.20, respectively.