The results of a multiproxy study on Mishrif carbonates from the margins of the Central Mesopotamian Basin of Iraq display a wide range of rock fabrics and diagenetic features, all affecting reservoir quality and flow properties in a complex manner. Based on petrographic and facies analyses of the Mishrif Formation in the AD oilfield, the model of a homoclinal ramp geometry with twelve characteristic microfacies types is proposed. A relevant observation is that the ramp, judging from the core data of the AD oilfield studied here, reflects low-energy conditions as documented by an abundancy of fine-grained carbonates in nearly all microfacies types. This notion is perhaps best understood in the context of an intrashelf basin with significant wave-seafloor interaction leading to wave degradation and a shallow effective wave base. In contrast to the rudist bioherms that typify the more basin-marginal settings, we find mainly evidence for small, low-relief buildups characterized by green algae. The Mishrif reservoir properties are shaped by two main diagenetic features: (i) early diagenetic, aquifer-related marine-meteoric mixing zone dissolution inducing abundant fabric selective porosity and (ii) the preferential cementation of Thalassinoides burrows leading to low-porosity concretionary carbonate nodules with reservoir properties that differ significantly from those of the host carbonate. Given the somewhat more distal position of the AD oilfield, the effects of prolonged stages of subaerial exposure related to sea-level fall, as reported from more basin marginal settings, are not recognized. The bending and splaying of seams around nodules and the well-preserved skeletal material within these concretionary carbonates demonstrate that the onset of nodule cementation was early diagenetic/pre-compactional in nature. Based on integrated microfacies and reservoir properties, seven rock types (i.e., Rock Type I-VII) with distinctive reservoir qualities are recognized. Nodular concretions are mainly developed in the Rock Type I lithology and result in distinctive cm-to dm-scale heterogeneity. The contrast between small, poorly-connected pore systems in nodules and medium-sized, well-connected pore systems in the host rock are best described as an inconspicuous, dual permeability system. Data shown here and evidence from other studies dealing with the Mishrif in the Central Mesopotamian Basin are important to understand and predict reservoir properties in other carbonate fields with similar properties.

对伊拉克美索不达米亚盆地中部边缘的 Mishrif 碳酸盐岩的多代理研究结果显示，岩石结构和成岩特征范围广泛，所有这些都以复杂的方式影响储层质量和流动特性。基于 AD 油田 Mishrif 组的岩相和相分析，提出了具有 12 种特征微相类型的同斜斜坡几何模型。一个相关的观察是，从这里研究的 AD 油田的核心数据来看，斜坡反映了低能量条件，正如几乎所有微相类型中大量细粒碳酸盐所记录的那样。在具有显着的波浪-海底相互作用导致波浪退化和浅的有效波浪基础的陆架内盆地的背景下，这个概念可能是最好的理解。与代表更多盆地边缘环境的原始生物礁相比，我们发现的主要证据是以绿藻为特征的小而低地势的堆积物。Mishrif 储层性质由两个主要成岩特征塑造：(i) 早期成岩、与含水层相关的海相-大气混合带溶解导致丰富的结构选择性孔隙度和 (ii) 优先胶结海藻导致低孔隙度胶结性碳酸盐结核的洞穴，其储层性质与主体碳酸盐的储层性质显着不同。鉴于 AD 油田位于更远的位置，与海平面下降相关的长期地下暴露阶段的影响（如更多盆地边缘环境所报告的那样）尚未得到承认。结核周围接缝的弯曲和张开以及这些胶结碳酸盐中保存完好的骨架材料表明，结核胶结的开始本质上是早期成岩/预压实作用。根据综合微相和储层性质，识别出具有独特储层性质的七种岩石类型（即岩石类型 I-VII）。节状结核主要发育在 I 类岩石岩性中，导致明显的 cm 至 dm 尺度的非均质性。结核中连接不良的小孔隙系统与主岩中连接良好的中型孔隙系统之间的对比最好被描述为不显眼的双渗透系统。此处显示的数据和其他研究中美索不达米亚盆地中部 Mishrif 的证据对于理解和预测其他具有类似特性的碳酸盐岩油田的储层特性非常重要。