The Sheikhan Limestone of Eocene age has been studied in detail covering its microfacies analysis, depositional setting, being a reservoir potential, and diagenetic sequence. For this purpose, two best exposed geological sections at Sheikhan Nala and Panoba section, Kohat Basin (Pakistan) have been selected. The techniques used for this research work are petrographic analysis, X-ray diffraction (XRD), cathodoluminescence (CL), pore plug porosity, and Scanning Electron Microscope (SEM) analysis. Typically, the Sheikhan Limestone is compacted, fossiliferous, and yellowish-grey in color, medium-thin bedded limestone with interbedded shale partings. The thickness of the studied limestone is 32 m to 44 m in the Sheikhan Nala and Panoba sections, respectively. A petrographic study reveals that calcite occurs in the form of micrite with a minor quantity of spare. Carbonate-filled fractures are common, as micro-veins. Detailed study reveals the diagenetic processes, and these include the imprints of micritization, neomorphism, cementation, compaction, dissolution, and fracturing. The dissolution and fractures enhance the reservoir characteristic, whereas clay minerals, micritization, compaction, and cementation reduces the reservoir potential of Sheikhan Limestone. The outcrop and petrographic studies have been used as a powerful tool to identify different microfacies. Based on all petrographic studies and microfacies analysis, it is suggested that the Eocene Sheikhan Limestone has been deposited under a shallow neritic inner shelf environment. Dissolution and fractures enhance the reservoir characteristics, whereas micritization, cementation, and compaction reduce the reservoir quality.

对始新世的谢汗石灰岩进行了详细的研究，包括其微相分析、沉积环境、储层潜力和成岩序列。为此，选择了位于科哈特盆地（巴基斯坦）的 Sheikhan Nala 和 Panoba 剖面的两个最佳暴露地质剖面。用于这项研究工作的技术是岩相分析、X 射线衍射 (XRD)、阴极发光 (CL)、孔塞孔隙率和扫描电子显微镜 (SEM) 分析。通常情况下，Sheikhan 石灰岩是致密的、化石的、黄灰色的、中等厚度的层状石灰岩，带有互层的页岩分界。Sheikhan Nala 和 Panoba 剖面研究的石灰岩厚度分别为 32 m 至 44 m。岩相学研究表明，方解石以微晶的形式存在，有少量的备用。碳酸盐填充的裂缝很常见，如微脉。详细研究揭示了成岩过程，其中包括微晶化、新形态、胶结、压实、溶解和压裂的印记。溶解和裂缝增强了储层特征，而粘土矿物、微晶化、压实和胶结降低了 Sheikhan 石灰岩的储层潜力。露头和岩相学研究已被用作识别不同微相的有力工具。基于所有岩相学研究和微相分析，表明始新世Sheikhan石灰岩沉积在浅浅海陆棚环境下。