临南洼陷南斜坡沙三段储层特征及控制因素

Reservoir Features and Controlling Factors of the 3th Members of Shahejie Formation in South Slope of Linnan Sag

针对临南洼陷南斜坡沙三段三大物源体系储层非均质性较强的问题,综合利用薄片鉴定、扫描电镜观察、X-衍射分析、图形分析处理等技术方法,对其储层特征及控制因素进行研究。结果表明,双丰辫状河三角洲、江家店三角州、瓦屋三角洲三大物源体系砂体均以岩屑长石砂岩为主,且储层物性依次变差。三大物源体系砂体均存在粒间孔、粒间溶孔、粒内溶孔、杂基内微孔和少量裂缝,但其孔隙结构存在明显差异,储集空间主要为次生溶孔。沙三段沉积微相中,三角洲和辫状河三角洲物性较好,浊积砂体较差。压实作用对物性的破坏主要与刚性颗粒的含量和埋深有关;碳酸盐胶结物含量低于5%时对物性影响不大,高于5%时,其含量与物性呈负相关关系;黏土胶结主要与其结晶形态(比表面)及在储层中的赋存状态有关。溶蚀作用和部分早期胶结作用对储层物性具有重要的改善作用。

Aiming at the reservoir heterogeneity of three sediment origins of the 3th members of Shahejie Formation in the south slope of Lingnan sag,the reservoir characteristics and controlling factors were studied by thin slice identification,SEM observation,X-ray diffraction analysis and graphic analysis.The results show that the sand bodies of the three sediment origins in the Shuangfeng braided river delta,Jiangjiadian and Wawu delta are dominated by lithic feldspathic sandstone,and the physical properties of the reservoir deteriorate in turn.There are intergranular pores,intergranular dissolved pores,intragranular dissolved pores,microporous intramatrix,and a few cracks in the sandstones of the three major source systems.However,there are obvious differences in their pore structure,and the main reservoir space is secondary dissolving hole.In the sedimentary microfacies of the 3th members of Shahejie Formation,the delta and braided river deltas have better physical properties and the turbidite sand bodies are poorer.Mechanical compaction is mainly related to the rigid particles and depth;when the content of carbonate cement is less than 5%,it has little effect on physical properties,and when it is higher than 5%,the content is negatively correlated with the physical properties.Clay cementation is mainly related to its crystalline form(specific surface)and its occurrence in the reservoir.Erosion and some early cementation play an important role in reservoir improvement.