Estimation of long-wavelength near-surface velocity and low-relief structural anomalies Part 2: A new near surface reconstruction method

In certain situations, velocity or structure anomalies in the near surface can cause a distortion in the structural interpretation of the deeper horizons. We present a tomographic approach, which tackles this problem by creating a detailed near surface depth-velocity model. The procedure uses three types of data; namely prestack depth migrated gathers, refraction delay times and refractor velocities, and zero offset travel times. The method is evaluated through tests on a synthetic data set where different combinations of input data are used. Results indicate that when all types of data are available, it is possible to resolve both the velocity and structure of the near surface horizons.