Abstract:Conventional hydrocarbon indication(HCI)technique is based on the variations of amplitude,frequency and velocity of seismic wave。It aims at locating the abnormal area in a seismic section where velocity and fre-quency drop,but amplitude enhances.Drilling data in SZ area show that seismic velocity in sandstone is lower than that in mudstone。ThLTs,the velocity difference between hydrocarbon-saturated sandstone and mud-stone will increase to result in amplitude enhancement,and this is just the requirement with which HCI technique can be used。By using HCI technique,reservoir reflections in SZ area were graded into four levels,Drilling discovered good hydrocarbon shows in the formations which are correlated with I and II level strong reflections.Detailed interval velociiy analysis(DIVA)is a hydrocarbon indica-tion method which is based on the fact that seismic velocity in a porous or hydrocarbon-saturated formation declines relatively.This method is easy,and it brings higher success rate than others because it avoids many noisy factors.