基于二维地震时深速度分析方法研究——以Bright盆地为例

The Velocity Analysis research of the Bright basin based on two dimensional seismic

Bright盆地是世界上最大的近海边缘盆地之一,资源潜力巨大;但是前期未能找到有效圈闭,钻遇有效储层,主要问题在于不能准确地换算出储层真实深度。影响时深转换的因素有很多,经过研究发现,主要的影响因素有以下几种:水深横向变化较大、构造发育复杂多样、工区横向的跨度较大、速度资料相对较少且没有深层速度资料,严重制约了时深转换的精度。为了准确找到有效圈闭,有必要重新开展全区精细构造解释和速度分析,通过纵向利用单井回归深层速度,横向利用层位约束速度建模的方法,计算不同层系速度网格速度,进而进行分层系变速度成图,大大提高了时深转换的精度,取得了很好的应用效果。

Bright basin is one of the world's largest offshore marginal basins,which has a huge resource potential.While effective pre-traps and effective reservoir failed to be found in the preliminary exploration,the main problem is what the true depth of the reservoir was not exactly converted.There are many factors which affect depth conversion.The main factors are the following,the changes of the sea water depth,complex structure,work area span and less velocity data.The most important factor was what there was no the deep velocity data,which severely restricted the time-depth conversion accuracy.In order to accurately find effective trap,it is necessary to re-launch the region's fine structural interpretation and velocity analysis.Through the use of a single well velocity data,the deep vertical velocity can be regression calculated.Then the velocity grid of the different layers can be calculated using the layers velocity modeling methods.At last,the variable velocity mapping can be done,which greatly improved the accuracy of the time-depth conversion and got a very good effect.