火山灰影响下的湖相富有机质页岩油成藏条件分析——以三塘湖盆地条湖-马朗凹陷芦草沟组为例  

Analysis of accumulation conditions of lacustrine organic-rich shale oil affected by volcanic ash: a case study of the Lucaogou Formation in the Tiaohu-Malang sag, Santanghu basin

作　　者：潘永帅 黄志龙[1,2] 郭小波 李天军 范谭广 徐雄飞 PAN Yongshuai;HUANG Zhilong;GUO Xiaobo;LI Tianjun;FAN Tanguang;XU Xiongfei(College of Geosciences,China University of Petroleum Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China;PetroChina Tuha Oilfield Company,Hami,Xinjiang 839009,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]油气资源与探测国家重点实验室,北京102249 [3]西安石油大学地球科学与工程学院,陕西西安710065 [4]中国石油吐哈油田分公司勘探开发研究院,新疆哈密839009

出　　处：《地质学报》2022年第3期1053-1068,共16页Acta Geologica Sinica

基　　金：国家自然科学基金重点项目(编号41702127)资助的成果。

摘　　要：三塘湖盆地条湖-马朗凹陷芦草沟组二段(芦二段)广泛发育一套火山灰与碳酸盐岩混合沉积的地层,但是芦二段页岩油的成藏条件和主控因素仍然不明确。本研究开展了有机/无机地球化学分析、岩芯常规分析(孔隙度、渗透率、含油饱和度)、全岩X射线衍射(XRD)、薄片、氩离子抛光-扫描电镜(FESEM)、高压压汞(HPMI)-核磁共振(NMR)联测等研究。结果显示:(1)芦二段发育一套湖相低熟—成熟的烃源岩,岩性以凝灰岩类为主,有机质类型以Ⅰ型为主,TOC平均可达5%,厚度大,品质好。(2)储层岩性复杂,各类岩性皆可作为储层,但物性较差,孔隙度介于1.1%-9.5%,渗透率总体低于0.1×10^(-3)μm^(2),储集空间类型以粒间孔,晶间孔和溶蚀孔为主。凝灰岩和白云岩的孔隙结构最好,含油饱和度较高,流体可动性较强,凝灰质白云岩次之,白云质凝灰岩最差。(3)优势的岩相,有利的源储组合,良好的断-缝系统控制芦二段页岩油富集成藏,具有“源储一体、优势相带控储、裂缝和溶蚀控制甜点”的成藏特征。A set of mixed sediments of volcanic ash and carbonate are widespread in the second Member of the Permian Lucaogou Formation(P_(2)l^(2)) in the Tiaohu-Malang sag, Santanghu basin. However, the conditions and main controlling factors of shale oil in the P_(2)l^(2)remain unclear. So, organic/inorganic geochemical analysis, core conventional analysis(porosity, permeability, and oil saturation), X-ray diffraction(XRD), thin sections, Ar-ion milled field emission scanning electron microscopy(FESEM), high pressure mercury injection(HPMI)-nuclear magnetic resonance(NMR),and other methods were used in this study. The results showed that:(1) The P_(2)l^(2)developed a set of low-mature and mature source rocks, which were dominated by tuff, with large thickness and high abundance of type Ⅰ kerogen, and an average TOC value of 5%.(2) The P_(2)l^(2)reservoir was characterized by complex lithology and poor physical properties, with porosity ranging from 1.1% to 9.5% and the permeability less than 0.1×10^(-3)μm^(2). Nanometer scale intergranular pores, intercrystalline pores, and dissolution pores were the main reservoir pore types. Tuff and dolomite have the best pore structure, higher oil saturation, and stronger fluid mobility, followed by tuffaceous dolomite and dolomitic tuff.(3) Advantage lithofacies, favorable source and reservoir combination, and good fault-fracture system control the P_(2)l^(2)shale oil accumulation, which has the characteristics of “source and reservoir integration, dominant facies belt control the reservoir, as well as fracture and dissolution control the sweet pot”.

关 键 词：页岩油 成藏条件 芦草沟组 条湖-马朗凹陷 三塘湖盆地 

分 类 号：P618.13[天文地球—矿床学]