Abstract：In 3-D seismic data processing,NMO-correction velocities far dipping-interface CMP trace gathers change with not only the 3-D positions and t0 times but also the observation directions of source-receiving lines.In order to get satisfactory NMO correction effect,we must do three-parameter velocity analysis(dip directian,dip angle,mean-square root velacityta get three-parameter velocity informatians of seismic reflectors before 3-D NMO correction.Additional double scanning is not feasible far getting dip direction and dip angle of formation because the computation is very tediously fang.Worldwide geophysicists'painstaking effarts(many attempts an three-parameter velocity analysis)have made the technique nearly feasible.Because of geophysicists'hard work,the saftwares far three-parameter velocity analysis came out one by one and bring initial effect.Nevertheless,the three-parameter velocity analysis is less perfect and less satisfactory than other usual velocity analysis techniques in seismic data processing;therefore,it needs further improvements so as to meet the technical requirements of high resolution and fidelity in 3-D seismic exploration.
