塔北地区黄山街组湖盆滩坝砂体沉积模式

Depositional Model for Lacustrine Beach Bars of Huangshanjie Formation in Tabei Area,Tarim Basin

查明陆相拗陷湖盆滩坝砂体发育特征及其主控因素,对该类型盆地岩性油气藏的勘探具有重要意义。综合利用钻井、测井和三维地震资料,对塔里木盆地塔北地区上三叠统黄山街组湖侵—高位体系域沉积时期发育的滩坝砂体进行了详细分析后指出,研究区滩坝砂体发育坝主体、坝侧缘、坝间、滩砂和湖湾泥5种微相,每种微相沉积特征差异明显。平面上滩坝砂体主要分布在研究区的西北部和东北部,其中西北部居主导地位,其他地区则零星孤立分布。滩坝砂体的形成与研究区特殊的地貌背景、水动力环境、湖平面变化以及沉积物供给条件密切相关。在对滩坝砂体沉积特征、分布规律及主控因素分析的基础上,建立了拗陷湖盆滩坝砂体沉积模式。

To find out characteristics and controlling factors of beach-bar sand bodies in a terrestrial down-warped lacustrine basin is ofgreat significance for lithologic reservoir exploration in it.In this paper,the characteristics of beach bars of transgressive systems tract andhighstand systems tract of Huangshanjie formation of the Upper Triassic in Tabei area（northern Tarim basin） were analyzed in detail,basedon the drilling,well log and 3D seismic data.The results show that five microfacies are identified in the beach bars,including bar body,baredge,interbar,beach sand and lake bay,with each microfacies having different sedimentary characteristics.The beach bars mainly developin the northwestern and northeastern Tabei,dominated by northwestern Tabei on the plane,and in other areas they are isolated distribution.The formation of beach bars is closely related to the special paleogeomorphology setting,hydrodynamic environment,lake level change andprovenance supply.Finally,based on the analysis of sedimentary characteristics,distribution and controlling factors of the beach bars,thedepositional model for such beach bars in the down-warped lacustrine basin is established.