合肥盆地速度场特征

通过地震测井及地震叠前深度偏移处理,合肥盆地沉积岩速度场表现出复杂的空间差异性。总体上看,埋深及岩性是控制速度的主要因素,中、新生界以侏罗系特别是下侏罗统的层速度高,普遍达5000～6000m/s以上,反映其岩性致密及埋深较大;以中、上白垩统及第三系层速度较低,成为合肥盆地油气勘探的主要目的层。侏罗系下伏的古生界—上元古界遭受了印支期强烈的冲断叠覆改造,其速度场异常复杂。综合分析认为,大桥凹陷是合肥盆地油气勘探的主要有利地区,以勘探白垩系低幅度背斜—半背斜圈闭及岩性圈闭天然气藏为主,因此,进行深入细致的地震速度分析处理及地质-地球物理一体化综合解释、有效地识别这些圈闭就成为当前勘探工作的关键。 

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.