东濮凹陷北部沙三段泥页岩微观储集空间特征及其主控因素

Microscopic Characteristics and Main Controlling Factors of Shale Reservoir Space of Es3 Formation,Northern Dongpu Depression

东濮凹陷北部沙三段盐湖沉积体系泥页岩具有良好的页岩油气潜力,本文通过多口钻井岩芯泥页岩全岩矿物X衍射、粘土矿物X衍射、氩离子抛光及能谱、扫描电镜等测试数据,研究了东濮凹陷北部沙三段陆相泥页岩微观储集空间特征及其主控因素。认为储集空间以微-纳米级孔隙为主,包括无机原生粒间孔、无机原生晶间孔、无机次生溶蚀孔、有机孔及微裂缝等孔隙类型。其中,无机孔隙,特别是次生孔隙,对页岩油气储层具有明显的建设作用,有机质孔发现较少。矿物成分、岩相类型、成岩作用、有机质丰度及成熟度是储集空间发育的主要影响因素,其中矿物成分是影响储集空间类型的内因;不同岩相类型对应的储集空间类型不同;成岩过程中易溶物质的溶蚀对储层物性的改善起到重要作用,垂向上粘土矿物成分演化与孔渗高值有较好的对应关系。

The shale in salt lake facies of Es3 formation in northern Dongpu depression has good potential of shale oil resources.By taking samples from shale wells and based on the experimental data of whole rock mineral X-ray diffraction,clay mineral X-ray diffraction,Ion beam polishing,and energy spectrum and scanning electron microscopy,the microscopic characteristics and main controlling factors of shale reservoir space were studied.Results show that the main type of reservoir space is micro-nanoscale pore,including inorganic primary inter-granular pore,inorganic primary inter-crystal pore,inorganic secondary dissolution pore,organic pore and micro-cracks.Inorganic pores,especially dissolution pores,play an important role in reservoir construction,and only few organic pores are discovered.The main controlling factors are mineral constituent,lithofacies,diagenesis,organic matters abundance and maturity.Mineral constituent is the endogenous factor;lithofacies and reservoir space type have a good match;the dissolution of the soluble matters during diagenetic process plays an important role in improving the physical properties of reservoir;and the upward clay mineral constituent and pore permeability have a good match.