Abstract：Step-optimized inversion of seismic data leads to a new borehole-free LOG processing method.The method offers interval velocity informations by making steped optimizatiorf,without the use of borehole informations and man`s intervention.It involves in the steps:·Use Oldenburg's algorithm to preprocess seismic data before inversion.·Compute interval velocity and good low-frequency components by modeled annealing method.·Take the low-frequency components as initial guess values of inversion.·Do iterative operation for better interval velocity informations by using conjugate gradient method.Theoretical modeling and data processing show that this method is characterized by high accuracy,good stability,excellent adaptability and nice noise-resistant ability,and that it results in high-resolution synthetic seismograms.
