塔里木盆地东部古城地区奧陶系碳酸盐岩微相特征和沉积环境

Microfacies Characteristics and Sedimentary Environment of Ordovician Carbonate Rocks from Gucheng Region in Eastern Tarim Basin

对塔里木盆地东部的勘探程度较低,是塔里木盆地未来油气勘探的新远景区,对其沉积微相类型及沉积演化认识较薄弱。采用碳酸盐岩微相分析的方法,以沉积学理论为指导,充分利用岩心、录井、测井、地震及岩石薄片等资料,分析了塔里木盆地东部古城地区中—下奥陶统碳酸盐岩微相类型、沉积特征及分布规律。研究表明,塔里木盆地东部古城地区中—下奥陶统碳酸盐岩发育8种微相类型,根据微相类型组合特征,尝试建立了研究区碳酸盐岩微相的空间展布模式,同时将研究区划分出局限台地、开阔台地、台地边缘和台缘斜坡等4个沉积相带;探讨了古城地区早-中奥陶纪沉积环境的演化,认为广泛发育的台地边缘浅滩形成了奥陶系碳酸盐岩是最为有利的储集相带。

The eastern Tarim Basin is a new field of petroleum exploration because the Ordovician carbonate reservoir hosts abundant oil and gas resources. However, researches on depositional microfacies and evolution are inadequate with a low exploration degree. Using the microfacies a- nalysis method and making full use of core, logging, well logging, seismic and rock slice, the mi- crofacies, sedimentary characteristics and distribution of Middle-Early Ordovician carbonate rocks in Gucheng region, eastern Tarim Basin have been analyzed. The results have shown that 8 mi- crofacies are recognized in these carbonate rocks, and the spatial distribution pattern of carbonate microfacies are established with different microfacies associations. Combining with macro geolog- ical background, the Middle-Early Ordovician Formation in Gucheng region can be divided into limited platform, open platform, platform margin, and carbonate ramp. And then, the evolutionof Early-Middle Ordovician sedimentary environment has been discussed, it＇s believed that the transgressive platform margin shoals formed favorable reservoir facies belts for Ordovician car- bonate rocks, because the sea is relatively shallow and gradually deepened.