High-resolution crosswell seismic with reflected waves.

Crosswell seismic data, acquired from two 100m deep, 80m apart boreholes, using sparker and hydrophones, are discussed. The data include in total more than 2000 seismic traces of high signal/noise ratio in the frequency range of 200-1800Hz. A velocity tomogram is produced by traveltime inversion of first breaks. Special processing, including common reflection point stacking of data, is applied for separation of reflected waves. The final stacked depth section is similar to that of field seismic, but the resolution of the first is 10-20 times higher.