涪陵区块下侏罗统页岩气形成条件分析及有利层系优选

发布时间：2018-06-11 21:50

  本文选题：涪陵区块 + 大二段　； 参考：《成都理工大学》2015年硕士论文

【摘要】：经过近几年的努力,我国四川盆地海相页气已取得了重大勘探突破,而陆相泥页岩形成条件复杂,研究相对较少。四川盆地陆相烃源岩主要为中侏罗统千佛崖组和下侏罗统自流井组泥质烃源岩、上三叠统煤系烃源岩。具有稳定的泥页岩分布,高有机质丰度、厚度大等特点,具有良好的页岩气成藏条件和巨大的勘探潜力。本文以“涪陵区块下侏罗统自流井组页岩气形成条件分析及有利层系优选”为题,利用野外剖面观察、测量和岩心观察以及泥页岩有机地化分析、物性分析、X衍射分析、比表面分析、扫描电镜等资料对涪陵下侏罗统自流井组富有机质泥页岩进行详细的分析,对页岩气富集条件进行深入的研究,分析优选出涪陵地区下侏罗统自流井组页岩气富集有利区域和有利层系。通过对涪陵下侏罗统自流井组页岩气富集条件研究,推动四川盆地下侏罗统页岩气的研究和勘探。通过对对涪陵区块下侏罗统自流井组的研究,明确了涪陵区块下侏罗统有利的沉积微相为半深湖风暴滩和半深湖泥;半深湖风暴滩沉积微相岩性以深灰色泥页岩与泥晶介屑灰岩、介壳灰岩不等厚互层为特征,半深湖泥沉积微相以黑色页岩、泥灰岩为特征,主要代表为涪陵大安寨段和东岳庙段;大安寨段分为大一段、大二段和大三段三个亚段。从涪陵地区陆相页岩气井沉积相柱状图得知涪陵大二段和东岳庙段发育较厚的暗色富有机质泥页岩,因此,涪陵下侏罗统自流井组研究重点为大二段和东岳庙段。据涪陵地区有机地化分析资料,大二段TOC平均1.33%,Ro平均值1.27%,处于成熟阶段,生成湿气为主,干酪根以Ⅱ2型为主;东岳庙段TOC平均1.78%,Ro平均值1.64%,处于高成熟阶段,生成湿气为主,干酪根以Ⅱ2型为主。据涪陵地区物性分析资料,大二段和东岳庙段储渗空间主要由孔隙与裂缝构成。孔隙类型主要包括粒间孔隙、晶间孔及少量有机质孔。裂缝类型主要为微型裂缝,包括硬性矿物边缘缝。其中纳米级至微米级的微孔隙与微裂缝对于页岩的孔渗发育、气体的储集与吸附起了重要的作用。涪陵地区大二段脆性矿物含量平均值为43.75%,东岳庙段脆性矿物含量平均值为43.9%,脆性矿物含量较高,可压性好。同时,涪陵地区陆相页岩气分布区域大多位于复向斜区,具有构造简单、稳定,地层平缓,断裂不发育,构造、保存条件良好。根据页岩气形成条件与主控因素,涪陵大二段和东岳庙段生烃条件优越,有机质含量高,整个研究区分布广泛,埋藏适中。从生烃条件、储集条件、保存条件综合分析优选出涪陵区块东北部为页岩气勘探开发的有利区域,东岳庙段为最优层系,大二段次之。
[Abstract]:Through the efforts in recent years, great breakthrough has been made in marine gas exploration in Sichuan Basin, while the formation conditions of continental shale are complex and the research is relatively few. The source rocks of continental facies in Sichuan Basin are mainly shaly source rocks of Qianfoya formation of Middle Jurassic and Artesian well formation of Lower Jurassic and source rocks of coal series of Upper Triassic. It has the characteristics of stable shale distribution, high organic matter abundance and large thickness, and has good shale gas reservoir forming conditions and great exploration potential. Under the title of "formation conditions of shale gas and optimal selection of favorable strata in Lower Jurassic Artesian well formation in Fuling Block", field profile observation, measurement and core observation, organic geochemistry analysis of mud shale, physical property analysis and X-ray diffraction analysis are used in this paper. The specific surface analysis, scanning electron microscope and other data are used to analyze the organic matter rich shale of the Lower Jurassic in Fuling, and the enrichment conditions of shale gas are studied in depth. The favorable regions and strata of shale gas enrichment in the Lower Jurassic Artesian well formation in Fuling area are analyzed. Through the study of the accumulation conditions of shale gas in the Lower Jurassic of Fuling, the study and exploration of the shale gas of the Lower Jurassic in Sichuan Basin are promoted. The favorable sedimentary microfacies of the Lower Jurassic in Fuling block are semi-deep lake storm beach and semi-deep lake mud through the study of the Lower Jurassic Artesian well formation in Fuling block, and the results show that the favorable sedimentary microfacies of the Lower Jurassic in Fuling block are semi-deep lake storm beach and semi-deep lake mud. The sedimentary microfacies lithology of semi-deep lake storm beach is characterized by dark gray shale and shaly mesozoic limestone, interbedded with interlayer of meso-shell limestone of unequal thickness, while the sedimentary microfacies of semi-deep lake mud are characterized by black shale and marlite. The main representative is the Fuling Da-anzhai and Dongyemiao sections, which are divided into three subsections: the first, the second and the third. From the column map of sedimentary facies of continental shale gas wells in Fuling area, it is known that thick dark organic matter rich mud shale is developed in the Daxian member of Fuling and Dongyemiao section. Therefore, the research emphasis of the Artesian well formation of Lower Jurassic in Fuling is the Dag2 and Dongyemiao sections. According to the organic geochemical analysis data of Fuling area, the average value of TOC in the second stage of TOC is 1.33 and Ro is 1.27, and it is in the mature stage, mainly producing wet gas, and the kerogen is mainly type 鈪，

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