南堡凹陷老爷庙构造陡坡带沙河街组扇体结构及油气意义

Fan-body Structures and Hydrocarbon Significances of Shahejie Formation in Steep Slope of Laoyemiao Areain Nanpu Depression

南堡凹陷老爷庙构造沙河街组钻井资料少、勘探程度及地质认识程度低。基于钻井及地震资料,开展地震层序分析,明确沙河街组扇体结构:北部西南庄断裂控制沙河街组沉积,断层倾角为30°~35°;识别出两个地震层序,层序由湖侵及湖退旋回构成,未见明显坡折带;平行物源方向(NS向)上,在两个湖退旋回中前积层延伸距离分别达到7.4 km及8.2 km,为加积-弱进积叠置;垂直物源方向上(WE向),见叠置的透镜状反射;下部层序前积扇体宽度为8.5~11.2 km,上部宽度为10.7~12.8 km,前积体在垂向加积的同时向东部侧向迁移。湖泛面厚层泥岩与下伏扇三角洲砂体叠置,加之扇三角洲前积砂体与沙三1段成熟烃源岩良好对接,构成有利生储盖组合。该认识对老爷庙构造深层天然气勘探提供有价值的参考。

The drilling data,exploration and geological understanding of Shahejie Formation of Laomiao Structure in Nanpu Depression arerare.Based on the drilling seismic data,the seismic sequence analysis was carried outand the fan body structures of Shahejie Formation were determined.The analysis results show that the Shahejie Formation sediments are controlled by Xinanzhuang Syn-Fault in North,and the fault dip angle is 30°~35°.Two seismic sequences are composed of transgression of regression cycles without obvious break slope.In the parallel provenance direction(NS direction),the extension distance of the forebody bed in the two regression cycles is 7.4 km and 8.2 km respectively,which is aggradation-weakly progradation stacking pattern.The overlapped lentoid reflections are recognized at vertical proven ancedirection(WE direction).The width of lower sequence forest fan body is 8.5 km to 11.2 km,and the upper width is 10.7 km to 12.8 km.The forebody migrates to the east side while accreting vertically.The overlying mudstone and the underlying fan body form two seal-reservoiras semblages,and the grogradational fan bodies and the mature source rocks in Shahejie31 section are well connected,forming a favorable hydrocarbon-reservoir-seal assemblage.This understanding providesa valuable reference for the deep gas exploration of Laoyemiao Structure.