CHARACTERISTICS OF VELOCITY FIELD IN THE HEFEI BASIN

Based on the results of well shooting and seismic pre-stack depth migration processing, the velocity field of sedimentary layers in the Hefei Basin showed complex difference. The velocity was mainly controlled by the buried depth and lithology of sedimentary layers. The Jurassic,especially the Lower Jurassic showed high interval velocity with 5 000-6 000m/s, indicating deep burying and compact lithology. The interval velocity in the Middle, the Upper Cretaceous and the Tertiary was lower, and the interval may be the target for petroleum exploration in the basin. The velocity field of the Paleozoic and the Neo-proterozoic underlying the Jurassic was very complex as a result of extensive thrust and overlap during the Indosinian movement.