银额盆地居延海坳陷钻井地层对比及对油气层时代的约束

Stratigraphic correlation of the wells of Juyanhai depression of Yingen-Ejin Basin and age constraints on oil and gas layers

【研究目的】银额盆地居延海坳陷具有良好的油气勘探前景,但钻井揭示的主要岩石地层单元时代及主要含油气层时代认识存在一定争议,因此系统开展地层划分对比,明确主要岩石地层单元与油气层的时代,对盆地构造沉积演化、油气地质条件评价与研究,以及勘探部署具有重要意义。【研究方法】对居延海坳陷不同凹陷钻井地层岩石学及岩性组合特征、古生物特征等综合研究,结合区域地层特征,建立钻井地层对比标志。并结合地震剖面确定不整合界面,以及侵入岩LA-ICP-MS锆石U-Pb年龄对地层时代的约束等,开展地层划分对比。【研究结果】居延海坳陷钻井揭示了白垩系与石炭系—二叠系2个构造层,各凹陷钻井地层对比标志显著,主要含油层系为下构造层的中—下二叠统及上石炭统—下二叠统干泉组。【结论】银额盆地为石炭纪—二叠纪与白垩纪的叠合盆地,石炭系—二叠系油气地质条件有利,应作为油气勘探的方向。

This paper is the result of oil and gas exploration engineering.[Objective]There is a good prospect of oil and gas exploration of Juyanhai depression of Yingen-Ejin Basin,but there are some controversies on the understanding of the age of the main petrostratigraphic unit and the age of the main oil-bearing reservoir revealed by wells,so it is great significance to the evaluation and study of oil and gas geological conditions,and the exploration and deployment by systematic stratigraphic division and correlation,and define the ages of the main petrostratigraphic units and oil and gas layers for the tectonic and sedimentary evolution of the basin.[Methods]Based on the comprehensive study on the petrology,lithologic association and paleontological characteristics of wells in different sags,,the formation correlation mark established by regional formation characteristics,unconformity interface determined by seismic profile,constraints on stratigraphic age of LAICP-MS zircon U-Pb and so on,the conclusion of stratigraphic division and correlation is formed.[Results]There are two structural layers of Cretaceous and Carboniferous and Permian of wells in Juyanhai depression,the correlation marks of strata in each depression are significant,and the main oil-bearing strata are the middle-Lower Permian and Ganquan formation of Upper Carboniferous and Lower Permian.[Conclusions]Yingen-Ejin Basin is a superimposed basin of Carboniferous-Permian and Cretaceous,and the geological conditions of Carboniferous and Permian are favorable,so it should be used as the direction of oil and gas exploration.