渤海海域中部古近系湖相碳酸盐岩储层成岩演化特征

渤海海域中部石臼坨凸起沙河街组优质储层分布是决定油气藏分布的关键要素，而成岩作用是控制沙河街组湖相碳酸盐岩储层发育的关键因素，准确分析成岩作用是提高该地区沙河街组储层预测的重要保障。利用偏光显微镜、荧光显微镜、扫描电镜、阴极发光、电子探针等实验分析技术，确定储层特征和成岩演化序列；利用黏土矿物X-射线衍射确定成岩阶段；利用气液两相包裹体均一温度和氧同位素地质温度计分析碳酸盐自生矿物的形成时期。沙河街组碳酸盐岩储层的岩石类型主要是生屑云岩，其次为砂屑云岩；储集空间以残余粒间原生孔和生物体腔孔为主；成岩作用主要特征为发育不同产出形态、多期次的自生白云石；建立了成岩演化序列，最终成岩阶段为中成岩B期；对储集物性有利的成岩作用是早成岩阶段形成的衬垫状白云石和同生期形成的包壳状白云石，其早期形成减弱了随后的压实作用对储层孔隙的破坏强度。

Diagenetic evolution characteristics of Paleogene lacustrine carbonate reservoirs in the central Bohai Sea area

High-quality reservoirs' distribution in the Shahejie Formation of the Shijiutuo Uplift in the central part of the Bohai Sea is a key factor in determining the distribution of oil and gas reservoirs,and the formation of rocks is a key factor in controlling the development of the lacustrine carbonate reservoirs.Accurate analysis of diagenesis is an important guarantee for improving the reservoir prediction of the Shahejie Formation.The experimental analysis techniques such as polarized light microscopy,fluorescence microscopy,scanning electron microscopy,cathodoluminescence,and electron probes were used to determine reservoir characteristics and diagenetic evolution sequences.The diagenetic stage was determined using X-ray diffraction of clay minerals.The period of formation of carbonate authigenic minerals was analyzed using gas-liquid two-phase inclusion homogenization temperature and oxygen isotope geological thermometers.Bioclastic dolostone is the main rock type in Shahejie Formation and the doloarenite is the minor;Reservoir space is dominated by residual primary intergranular pores and visceral cavity pores;The authigenic dolomites with different occurrences and different stages are the critical character of diagenesis.Diagenetic evolution sequence is established and the latest diagenetic period is the phase B of the middle diagenetic stage.The pore-lining dolomites of the early diagenetic stage and the coating dolomites of the syndiagenetic stage which reduce the destruction strength of the mechanical compaction to the porosity are the most effective products of the diagenesis.