拟声波地震反演在三角洲前缘河道砂体预测中的应用

Application of quasi-acoustic seismic inversion to predict sandbody in delta front channel

大港油田南部滩海地区主要含油层系为沙河街组沙二段,沙河街组地层形成于黄骅坳陷的扩张期,也是下第三系的首次大规模湖侵期,湖岸附近地形高差大,岸上斜坡陡窄,物源近,碎屑物质供应充足,河道砂岩薄互层发育,储层纵向厚度变化大,平面分布复杂。本区域内砂、泥岩声波速度差异小,常规声波反演预测砂岩效果差,不能达到生产需要。本次研究重构拟声波曲线,突出储层与围岩差异,较好地完成对厚层砂岩边界预测的同时,对薄层砂岩边界也能精确识别,实现了对三角洲前缘河道薄互层砂砾岩储集层预测的目的。

The main oil-bearing stratum in the south shallow water area of Dagang oilfield is located in Sha-2 zone of Shahejie formation.Shahejie formation is deposited in the spreading period of Huanghua depression and also the first large scale lacustrine transgression period of Eogene system,and the characteristics are large topographic height difference near the lake bank,steep slope in the bank,nearby provenance,abundant fragments supply,thin interbed development in channel sandbody,large vertical thickness change in reservoirs,complex plane distribution.Because the difference of acoustic wave velocity between sandstone and mudstone in this area is small,the effect of sandstone prediction with conventional acoustic wave inversion can't meet the productive need.This study rebuilds the quasi-acoustic curve,highlights the difference between reservoir and surrounding rock,and preferably completes the prediction of thick sandstone boundary,at the same time,this boundary of thin sandstone is recognized precisely in this study.Finally the purpose of glutenite reservoir prediction in the thin interbed of delta front channel is realized in this study.