阿姆河右岸中下侏罗统沉积相及平面展布

Sedimentary Facies and Its Lateral Distribution of the Middle-lower Jurassic in Amu Darya Right Bank Area

通过对阿姆河右岸中下侏罗统的岩石学、测井相与地震相特征进行分析,结合区域构造–沉积背景,对阿姆河右岸中下侏罗统的沉积相进行了研究,认为该套地层主要为陆相碎屑岩沉积体系,在顶部相变为海陆过渡层系,共识别出了三角洲前缘、滨湖、浅湖和潮下4类沉积亚相以及12类沉积微相。通过对沉积相纵向演化和平面分布特征的分析,揭示出研究区在早中侏罗世经历了两次水进沉积演化过程,研究区的主体沉积环境为滨—浅湖亚相,三角洲前缘亚相仅在早中侏罗世早期的B区东部及A区有小范围发育。这种湖泊—三角洲的滨岸沉积使研究区中下侏罗统不仅发育有机质含量丰富且广泛分布的优质烃源岩层,也发育具有一定储集能力的油气储集层。

The aim of this paper is to study the characteristics of sedimentary facies of the Middle-lower Jurassic in Amu Darya Right Bank Area according to the analysis of lithology,logging facies,seismic facies as well as regional structural and sedimentary background. The research shows that the Middle-Lower Jurassic stratum consists predominately of continental clastic deposits with small amount of marine-continental transitional sediments at the top. On this basis,four sedimentary subfacies including delta front,lakeshore,shallow lake,subtidal zone and twelve microfacies are identified. By studying the sedimentary evolution and lateral distribution characters,we identified two transgressive sequences in this stratum. The dominate sedimentary environment is shore-shallow lacustrine subfacies,while delta front subfacies are only present in limited areas of A block and the eastern B block in the early Middle-lower Jurassic. The lacustrine and deltaic environment contributes not only to the development of high quality source rocks,which are wide-spreading,but also to the development of reservoirs in the study area.