Method for building stratum velocity model

The invention provides a method for building a stratum velocity model, which comprises the steps of (A) acquiring existing seismic data of a work area, (B) acquiring pre-stack time migration seismic data volume and pre-stack time migration imaging velocity of the work area, (C) acquiring seismic reflection stratum data of the time domain of each stratum in the work area and fault data of the work area, (D) acquiring pre-stack depth migration velocity volume of the work area, (E) determining a time-depth curve of well drilling in the work area according to an acoustic logging curve and the pre-stack time migration seismic data volume, (F) acquiring well seismic pseudo velocity of well drilling in the work area, (G) establishing a framework model of the work area, (H) establishing a stratum velocity model according to the pre-stack depth migration velocity volume, the time-depth curve of well drilling, the well seismic pseudo velocity of well drilling and the framework model of the work area, and (I) carrying out correction on the stratum velocity model by using while-drilling materials so as to acquire a while-drilling stratum velocity model. The precision of the stratum velocity model can be effectively improved according to the method provided by the invention.