【作者】 李兆丰；

【导师】 唐相路；

【作者基本信息】 中国石油大学(北京) ， 地质资源与地质工程， 2021， 硕士

【摘要】 页岩油气是非常规油气中的研究热点。中国陆相含油气盆地普遍分布,陆相页岩岩性变化快,沉积构造多变,储层非均质性强。传统的岩相划分方案很难准确反映陆相页岩岩石学特征,不利于表征其复杂的沉积变化规律,制约了页岩油气的甜点优选及有利区预测。因此需要建立有效的陆相页岩岩相划分方案,查明其微观储集空间特征。本次研究选取玛湖凹陷北缘风城组页岩作为研究对象,通过元素测井、有机地化测试、扫描电镜、高压压汞、氮气吸附等方法,建立风城组页岩岩相划分方案,明确风城组页岩储层发育特征,分析不同岩相对页岩储层微观孔缝系统的控制作用。玛湖凹陷北缘风城组页岩为半干旱气候,浅水高盐环境沉积;TOC普遍大于0.5%,整体处于低熟-成熟阶段,以Ⅱ₂型干酪根为主。基于矿物组成—沉积构造特征对玛湖凹陷北缘风城组页岩岩相进行划分,识别5种主要岩相:纹层状长英质页岩、块状含云长英质页岩、纹层状含长英云质页岩、纹层状含粘土长英质页岩以及块状粉砂岩夹层。通过MY1井岩心精细描述及测井响应特征,建立6种主要的岩相组合。长英质页岩多发育长英质条带、团块;含云长英质页岩、含长英云质页岩常见不规则云化,长英质与云质纹层、条带常伴生发育。玛湖凹陷北缘风城组页岩储层微观孔隙结构复杂多样,宏观裂缝、微裂缝均有发育。矿物组成是不同岩相页岩储层的孔缝系统差异发育的主要影响因素。长英质矿物的成孔能力相对较强,碳酸盐矿物次之,粘土矿物最差。粉砂岩和长英质页岩的宏孔孔隙、裂缝均发育,微裂缝与孔隙沟通较好,可形成宏观裂缝-微裂缝-宏孔的储集模式,是储集能力最好的两种岩相。更多还原

【Abstract】 Shale oil and gas is a hot topic in unconventional oil and gas research.The continental oil and gas basins in China are widely distributed,with the rapid change of the lithology,the changeable sedimentary structures and the strong heterogeneity of the reservoir.The traditional lithofacies division scheme is difficult to accurately reflect the petrological characteristics of continental shale,which is not conducive to the characterization of its complex sedimentary change law,and restricts the sweet spot optimization and favorable area prediction of shale oil and gas.Therefore,it is necessary to establish an effective scheme for lithofacies division of continental shale and find out the micro space characteristics.In this study,the Fengcheng Formation shale in the northern Mahu sag is selected as the research object.By means of element logging,organic geochemical testing,scanning electron microscopy（SEM）,high pressure mercury injection,nitrogen adsorption and other methods,the lithofacies division scheme of Fengcheng Formation shale is established,the development characteristics of Fengcheng Formation shale reservoir are clarified,and the control effect of different rock phases on the micro pore fracture system of shale reservoir is analyzed.The Fengcheng Formation shale in the northern Mahu sag is deposited in a semi-arid climate,shallow water and high salinity environment,and TOC is generally more than 0.5%,which is in the low mature stage.The type of organic matter is mainly typeⅡ₂kerogen.Based on the characteristics of mineral composition and sedimentary structure,the shale lithofacies of Fengcheng Formation in the northern Mahu sag are divided,and five main lithofacies are identified:laminated felsic shale,massive dolomitic felsic shale,laminated felsic dolomitic shale,laminated argillaceous felsic shale and massive siltstone interlayer.Through the fine description of core and logging response characteristics of MY1 well,six main lithofacies combinations are established:argillaceous felsic shale with argillaceous shale interlayer,dolomitic shale mixed with siltstone interlayer,felsic shale with dolomitic felsic shale interlayer,dolomitic felsic shale with felsic shale interlayer,interbedding of felsic shale and dolomitic felsic shale and interbedding of felsic shale and calcareous shale.The micro pore types of Fengcheng Formation shale reservoir in the northern Mahu sag are various,and the fractures are developed.Mineral composition is the main factor affecting the characteristics of pore-fracture systems in different lithofacies shale reservoirs.The pore forming ability of felsic minerals is relatively well,followed by carbonate minerals,then clay minerals.The siltstone and felsic shale,whose macropores and fractures are well developed and connected,can form a reservoir model as macrofracture-microfracture-macropore,which are the two lithofacies with the best reservoir capacity.更多还原