伊拉克中南部艾哈代布油田的中上白垩统生物碎屑灰岩构成两类储集层：中高孔渗储集层和中高孔低渗储集层。两类储集层的形成环境、储集空间、孔隙结构及孔渗性能等均不相同。前者主要发育在台内滩亚相颗粒灰岩类中，以铸模孔、非组构选择性溶孔、粒内溶孔和粒间孔为主，具有良好的孔喉配置关系，储渗性能较好，为本区最优质的储集层。后者主要发育在能量较低的泥晶灰岩类中，以体腔孔和晶间孔等孔隙为主，孔喉配置稍差，渗透性能较差。储集层受到沉积相和建设性成岩作用的控制。台内滩亚相是最有利的沉积相带，溶蚀作用、新生变形作用和白云石化作用是本区绝大多数次生孔隙形成的主控因素，其中同生期和表生期的溶蚀作用是本区有利储层形成的关键。

The Middle-Upper Cretaceous bioclastic limestone reservoirs can be classified into two types, one with high-porosity and high-permeability and the other with high-porosity and low-permeability, in Ahdeb Oil Field located in the central and southern parts of Iraq. These reservoirs are different in sedimentary environments, reservoir spaces and pore textures as well as porosity and permeability. The high-porosity and high-permeability reservoirs usually develop in grainstone in intra-platform shoal subfacies, in which the pore spaces are commonly composed of mouldic pores, non-fabric selective dissolution pores, intragranular dissolved pores and intergranular pores. This type of reservoirs belongs to the best reservoirs with good configuration of pores and throats, and high porosity and permeability. The high porosity and low permeability reservoirs mainly develop in the low-energy micrite limestone, in which the pore spaces are commonly composed of intrafossil pores and intercrystal pores. This type of reservoirs is of poor configuration of pores and throats and very low permeability. It is shown that the reservoirs are controlled by sedimentary facies and constructive diagenesis so that the intra-platform shoal is the most favorable depositional facies and the dissolution, neomorphism and dolomitization lead to the majority of secondary porosity. Besides, the syngenetic dissolution and supergene dissolution are the keys of forming favorable reservoirs.