Abstract:Both in-line spread and broadside are used in 3-D seismic exploration. The two kinds of detection system lead to different CDP time-distance curves and different stacking velocities, thus resulting in their t moveout after stack. The moveout has to do with tre following factors: formation dip, the angle included between seismic line and formation dip direction, the angle included between seismic line and shot-receiver line, the angle included between shot-receiver line and formation dip direc lion, normal distance between shot point and broadside, and the maximum off-set, etc. Therefore, these factors should be taken into account in designing a 3-D detection system.