济阳坳陷不同岩相页岩油赋存机理

Occurrence mechanism of shale oil with different lithofacies in Jiyang depression

通过大量岩心观察、薄片鉴定、X-射线衍射全岩矿物分析和扫描电镜分析,将济阳坳陷古近系泥页岩划分为10余种岩相并分析了主力岩相的特征和形成环境。在岩相划分的基础上,结合氩离子抛光和环境扫描电镜技术,分析了不同岩相的储集空间和页岩油赋存状态。济阳坳陷泥页岩的储集空间主要包括各类基质的孔隙和裂缝。富有机质纹层状泥质灰岩/灰质泥岩储集空间是方解石晶间孔、黏土矿物晶间孔、层间缝,孔隙最大,裂缝最发育;富有机质层状泥质灰岩/灰质泥岩储集空间是方解石晶间孔、黏土矿物晶间孔、(微)裂缝;含有机质块状灰质泥岩储集空间是黏土矿物晶间孔,孔隙最小,裂缝不发育。不同岩相有不同的赋存状态,富有机质纹层状灰质泥岩相/泥质灰岩相和层状灰质泥岩相/泥质灰岩相以游离态为主,含有机质块状灰质泥岩相以吸附态为主。建立了富有机质纹层状-层状岩相和含有机质块状岩相2种页岩油赋存模式。

According to massive core observations,thin section identification,X-ray diffraction whole-rock mineral analysis and scanning electron microscopy,the Paleogene mud shale in Jiyang depression can be divided into more than 10 kinds of lithofacies to analyze the characteristics and formation environment of chief lithofacies.On the basis of lithofacies division,the reserving spaces of different lithofacies and shale oil occurrence states were analyzed in combination with argon ion polishing and environmental scanning electron microscope.The reserving spaces of mud shale in Jiyang depression mainly include various matrix pores and fractures.The reserving spaces of organic-rich laminated argillaceous limestone/calcareous mudstone are intercrystaline pores of calcite and clay minerals as well as interbedded fractures,characterized by the largest pores and the most developed fractures.The reserving spaces of organic-rich layered argillaceous limestone/calcareous mudstone are intercrystaline pores of calcite,intercrystaline pore of clay minerals and（micro）fractures.Those of organic massive calcareous mudstone are intercrystaline pores of clay minerals,characterized by the smallest pores and nondevelopment of fractures.Different lithofacies have different occurrence states.The organic-rich laminated argillaceous limestone facies/calcareous mudstone facies and organic-rich layered argillaceous limestone facies/calcareous mudstone facies are dominated by free state,while organic massive calcareous mudstone is dominated by adsorption state.Two occurrence modes of shale oil have been established,i.e.,organic-rich laminated-layered lithofacies and organic massive lithofacies.