利用地震相识别优质烃源岩——以辽中凹陷沙三段为例

Identification of High-quality Source Rocks by Seismic Facies:Taking the third member of Shahejie Formation in Liaozhong Depression as an example

利用地震资料,在沙三段精细层位标定的基础上,进行辽中凹陷沙三段地震地层的追踪解释。根据优质烃源岩的定义及判识标准,即主要为一套富含有机质的中深湖相暗色泥岩沉积,识别出优质烃源岩地震相主要呈低频、连续、强反射特征。在地震相和沉积相分析的基础上,建立了辽中凹陷三个次洼优质烃源岩地震相—沉积相模式,并对辽中凹陷沙三段优质烃源岩进行了分布预测,研究表明辽中凹陷沙三段优质烃源岩在北洼分布范围较大,中洼次之,南洼分布最小;在辽中北洼,整个沙三段均有分布;在辽中凹陷中洼,优质烃源岩发育于沙三中亚段;在辽中凹陷南洼,主要发育于沙三段下部。

Based on fine horizon calibration of the third member of Shahejie formation in Liaozhong Depression,seismic stratigraphic interpretation is completed by seismic modeling.According to the definition and criterion of identification of high-quality hydrocarbon source rocks,mainly for dark mudstone with rich organic matter of semideep-deep lacustrine facies,features of seismic facies such as low frequency,continuation and strong reflection is identified.Based on the analysis of seismic facies and sedimentary facies,seismic-sedimentary facies models are established and distribution of high-quality hydrocarbon source rocks of Shahejie Formation in Liaozhong Depression is predicted.The results show that high-quality hydrocarbon source rocks is mainly distributed in the north sag of Liaozhong Depression,the range decreases gradually from north to south.In the north,high-quality hydrocarbon source rocks is well developed,but in the central area and south,It is only developed in the middle and lower part of the third member of Shahejie Formation,respectively.