Abstract: With the development of technologies for geological exploration, the structural maps with higher accuracy have been needed, and the higher requirements for developing seismic velocity fields and structure-mapping methods with variable velocities have been proposed. In this paper, studies on combination of stack velocity field with t₀ horizon field, picking up t₀ time varied rate in different blocks and segments of all controlling horizons are conducted, based on the 2D seismic data, conventional hori-zon control approach for developing seismic velocity field and using optimized horizon control method. Also, by developed 3D model, the interval velocity is calculated, base-level selection and correction is made, time-depth conversion is performed with re-fracted tracing method; by well log input data, quick corrections of interval velocity and depth maps by using drilling individual-layei data are discussed. Hence,the mapping accuracy could be improved,obtaining satisfied effects of mapping structures.

Key words: interval velocity, base-level correction, control, 3D, accuracy