冀中坳陷奥陶系层序古地理及储层特征

ORDOVICIAN SEQUENCE PALEOGEOGRAPHY AND RESERVIOR QUALITY IN JIZHONG DEPRESSION

冀中坳陷在奥陶纪为华北陆表海的一部分,形成了一套碳酸盐岩地层。下奥陶统分为冶里组和亮甲山组,中奥陶统仅存马家沟组,可分为6段,上统缺失。早奥陶世本区以潮坪和局限台地沉积为主,中奥陶世呈现局限台地和开阔台地相间分布的格局。奥陶系储层受岩性、沉积相、成岩作用、断层、裂缝作用等多种因素控制,可分为白云岩晶间(溶)孔型、裂缝型和古岩溶型3种类型,总体上属较好—差储层。其中饶阳凹陷、文安斜坡带、廊固凹陷、武清凹陷和晋东斜坡区为较好储集岩分布区。

In the Ordovician,the Jizhong depression was one part of the Huabei epicontinental sea,in which a set of carbonate formations deposited.The Lower Ordovician consists of the Yeli Formation and Liangjiashan Formation,and the Middle Ordovician only contains the Majiagou Formation,which is further divided into six members.The Upper Ordovician is missing.In the early Ordovician,the study area was mainly occupied by tidal flats and restricted platforms.During the middle Ordovician,however,the area was characterized by open platforms and restricted platforms.The formation of reservoirs depends upon various factors,such as lithology,facies,diagenesis,faults and fractures.They are classified into three main types,i.e.fracture type,karst cave type and the type of intercrystal pores of dolomite,with relatively higher or lower capacities.Relatively good reservoirs are distributed in Raoyang,Wenan,Langgu,Wuqing and Jindong regions.