鄂尔多斯盆地奥陶系顶面形成演化与储集层发育

从奥陶系顶面在不同地质历史时期的演化、反转入手,探讨构造演化对鄂尔多斯盆地奥陶系不同类型储集体发育的控制作用,研究碳酸盐岩储集层形成演化机理。鄂尔多斯盆地奥陶系顶面为一重要的层序界面,其既代表了下部海相碳酸盐岩沉积建造与上部碎屑岩沉积建造之间的构造沉积转换,又代表了加里东晚期—海西早期漫长风化剥蚀造成的区域性地层沉积间断。该界面在地质历史时期经历了3次重大的构造格局演变,直接影响了奥陶系储集层的发育及后期保存。盆地东、西部奥陶系顶部岩性差异控制了发育的储集空间类型,形成了不同类型的溶蚀孔洞储集体;而后期层序界面构造倒转则造成盆地东部地区岩溶孔洞型储集空间被充填,影响了有效储集层的空间展布范围。

Evolution of the Ordovician top boundary and its relationship to reservoirs' development, Ordos Basin

The control of structural evolution on the development of different types of Ordovician reservoirs in the Ordos Basin is discussed by studying the evolution of the Ordovician top boundary in geological times,and the mechanisms of formation and evolution of carbonate reservoirs are examined.The top boundary of the Ordovician is an important sequence boundary in the Ordos Basin.It represents not only the depositional change between lower marine carbonate rocks and upper clastic rocks,but also a depositional break caused by weathering and corrosion from the Late Calidonian to the Early Hercynian.It experienced three great structural changes in the geological history,which influenced the formation and conservation of the Ordovician reservoirs.Lithology difference of the Ordovician top sequence between the east and west of the basin controlled the type of reservoir space and caused the formation of different reservoirs of corrosive pores.However,the later reversal of the sequence boundary causes the filling of early formed pore space in the eastern basin,and affects the space distribution of effective reservoirs.