塔里木盆地奥陶系层序地层格架及其对碳酸盐岩储集体发育的控制

在纵向上,塔里木盆地奥陶系中可识别出了18个三级层序、5个超层序和2个超层序组。平面上同,由西往东奥陶系沉积由碳酸盐台地依次过渡为斜坡相和盆地相,其层序的发育呈现由西向东的不断前积,一系列呈前积型的层序向东下超在一个较大规模的下超面上。不同级别的层序界面对塔里木盆地奥陶系碳酸盐岩储层的发育具有重要的控制作用。三级层序界面导致的短暂暴露及其同生期的成岩作用对台地边缘礁滩相储集体的改造具有重要的促进作用,而与高级别层序界面相对应的大型不整合面是控制塔里木盆地奥陶系碳酸盐岩岩溶储层发育的关键。

Sequence stratigraphic framework and its control on development of Ordovician carbonate reservoir in Tarim basin

Vertically,the Ordovician in Tarim basin can be divided into 2 supersequence groups,which can be further divided into 5 supersequences and 18 third-order sequences.Laterally,from west to east,the Ordovician deposits transit successively from platform facies to slope and basin facies,and the development of stratigraphic sequences ap- pear to be progressive progradation resulting in the downlapping of a series of prograded sequences onto a relatively large downlapping surface.Sequence boundaries of various orders have important control on the development of Or- dovician carbonate reservoirs in Tarim basin.The transient exposure caused by the third-order sequence boundaries and the synchronous diagenesis would have facilitated the modification of reef-bank facies reservoirs on the edge of the platform corresponding the large unconformities,which correspond to the sequence boundaries of higher levels might be the key factors that have controlled the development of the Ordovician carbonate karstic reservoirs in Tarim basin.