辽东凹陷南洼斜坡型源-汇系统发育特征及控砂作用

Characteristics of slope source-to-sink system and its control on sand body in southern Liaodong sag,Bohai sea

渤海海域辽东凹陷南洼东部斜坡带古近系沙二段沉积时期发育典型的斜坡型源-汇系统,明确砂体优势发育区是储层预测的难点。运用源-汇系统控砂理论,综合开展了古地貌恢复与层序地层学分级研究,对研究区源-汇系统各要素特征及其配置关系进行了刻画与分析,明确了斜坡型源-汇系统的控砂机制。研究表明:物源体系-沟谷体系-坡折体系的源-汇配置关系控制了砂体优势汇聚方向,二级层序发育特征控制了砂体发育时期,时空关系的有效耦合控制了沉积体系的宏观分布规律;沉积区微古地貌与高频层序共同控制了斜坡型源-汇系统的多期砂体精细发育模式。本文研究结果为薄地层内砂岩储层分析与预测以及海上少井条件下的油气藏勘探评价提供了技术支撑。

The eastern slope of southern Liaodong sag is a typical slope source-to-sink system in Es2, and the favorable sand converging area is difficult to predict. Based on the controlling sand principle of source-to-sink, the paleotopography restoration and multi-level sequence stratigraphy study are carried out, each element of source-to-sink system and their coupling relationship are characterized and the controlling mechanism on sand converging of slope source-to-sink system are concluded. The studies show that effective matching of provenance, valley and slope controls the favorable directions of sand converging; the second-order sequences control the periods of sand deposition; the coupling relationship of the two factors above controls the macroscopic distribution regularity of sedimentary system; the features of micro- paleotopography and high frequency sequences control the subtle distribution characteristics of multi-stages sand body. The research provides technical support for sand reservoir analysis and distribution prediction in thin strata and the exploration and evaluation of offshore reservoirs with sparse wells.