南海中建南盆地速度资料分析与应用

在大量速度谱解释的基础上,分别计算了南海中建南盆地的层速度、时深转换和砂岩百分含量,并对盆地5套地层的层速度平面图进行了分析。结果表明,中部坳陷的层速度最大,北部坳陷和南部坳陷次之,北部隆起的层速度最小,反映了地层的构造走势;利用砂岩百分含量资料进行岩性分析,发现西北部和西南部的砂岩百分含量大于75%,属于砂岩相沉积,推测盆地的物源主要来自西北和西南方向,为沉积相解释和油气资源评价提供了依据。

Velocity data analysis and its application to Zhongjiannan Basin in South China Sea

The interval velocity,time-depth conversion and sand content of the Zhongjiannan Basin in the South China Sea are calculated based on interpretation of velocity spectra.The analysis of the plane map of interval velocity from five sets of the strata in the basin indicates that the interval velocity of the middle sag is maximal,those of the north and south sags are the next in order,and that of the north rise is minimal,reflecting the structure trend of the strata.The lithologic analysis shows that the sand content of the sediments in the northwest and the southwest exceed 75 percent,suggesting that they belong to arenaceous lithofacies.So it can be deduced that the deposit in the basin is mainly from the northwest and southwest.This conclusion will provide a quantitative basis for lithofacies division and appraisal of petroleum and na-(tural) gas resources in the Zhongjiannan Basin.