【作者】 吕宝凤；

【导师】 张晏华； 夏斌；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 构造地质学， 2005， 博士

【摘要】 四川盆地是我国大型含油气盆地,也是我国西南部重要的天然气产出基地。四川盆地东南地区下古生界为天然气勘探新领域,勘探和研究程度均较低,具有目的层埋藏深、多期改造、多期成藏、构造变形程度高、地质结构复杂及烃源岩高-过成熟演化等诸多特点,天然气藏的形成和分布主要受大地构造背景、盆地构造格架及断层控制。近年来的研究和勘探工作表明研究区具有很好的天然气勘探前景,可以作为四川盆地下一步天然气勘探的战略接替区。 本文以活动论、构造历史观作指导,运用大陆动力学、构造地质学及含油气系统理论和方法,以盆地构造-沉积分析技术为手段,通过研究川东南地区区域构造背景、大地构造演化特征、构造变形的方式和程度及其对油气成藏的控制,结合烃源岩、储集层、盖层及圈闭条件的研究,分析了川东南地区下古生界天然气藏形成和分布的基本规律,进而指出了有利勘探区带和下一步工作建议。 研究内容主要包括:(1)地层层序和沉积环境研究;(2)大地构造背景和构造演化阶段研究;(3)构造变形基本特征研究;(4)典型气藏剖析及天然气成藏条件研究;(5)含油气系统研究;(6)有利勘探区带优选。 本文以大量的勘探资料为依据,野外工作与室内工作相结合,通过对川东南地区的地质、地物、钻井及油气前景资料的综合分析研究,取得了以下重要成果: 川东南地区下古生界以海相沉积为主,纵向上可以划分为4个Ⅱ级层序、33个Ⅲ级层序,其中志留系8个Ⅲ级层序、奥陶系8个Ⅲ级层序、寒武系13个Ⅲ级层序、震旦系灯影组上段4个Ⅲ级层序; 加里东-海西期的伸展构造环境奠定了腹底断层的基础,印支运动以来,特别是在喜马拉雅运动期间,华南陆块受周围板块的强烈挤压所形成的强大的北西-南东向压扭性应力场是导致四川盆地构造格局形成和川东南地区“隔档式构造”产生的直接原因,并于喜马拉雅运动晚期将其最后定形; 川东南地区众多的局部构造都是在统一机理的作用下形成的,背斜幅度高低、强度大小、形态变化主要是受控于它们所处的区域构造位置、受力的大小和方式、纵向上地层组合、基底及边界条件等因素,多数是中生界褶皱构造与下古生界断块叠合而成的“双层花状构造’’的叠合体,其形成经过了褶前张裂、初期更多还原

【Abstract】 Sichuan basin is one of Chinese largest petroliferous basins, as well as a significant natural gas producing region in southwest China. As a new gas exploring field, the lower paleozoic of southeast Sichuan basin has almost not been studied, because its arming strata were deeply buried, and it is characterized by the multiphase deformation, the multiphase bed forming, the perplexing tectonic, the high-over evolution of petroleum, and the gas distribution and migration controlled by tectonic background, basin structure trellis and fault zones. In recent years, a lot of exploring work indicates that the studying area has such a capacious gas foreground that it can be chosen as an exploration-tactic superseding area of Sichuan basin in future.This paper deals with the study of the rules of accumulation and distribution of petroleum, which is based on the analysis of the tectonic background, the features of structural evolution, the types of the tectonization and their significant influences for the formations of gas pools. Then the promising areas were pointed out and some advices for next exploration work were given.The study includes: (1) the study of the strata order and the sediment environment; (2) the study of the tectonic background and the evolution stage; (3) the study of the tectonic deformation of the basin; (4) the study of the typical gas pool and the bed forming; (5) the study of the petroleum system; (6) the selection of the prospective areasAccording to sufficient practical data and the combination of open field work with indoor work, the article has achieved much, such as bellow:The lower paleozoic of southeast Sichuan basin is made of marine deposits, whichcould be divided into four grade- II sequences and thirty three grade-III sequences.The elongational environment from Caledonian to Hercynian caused the foundation of deep faults. It was the compresso-shear stress field towards NW in south China that caused ejective structures in southeast Sichuan, the transformation began in Indosinian movement, and their main tectonization happened in the late period of Himalayan orogeny.Local structures in southeast Sichuan are formed in the same tectonization mechanism. The differences of folding scale, the folding ships and the folding degrees are related closely to their tectonic locations, directions and patterns of the stress, and their vertical organizations of layers, and the conditions of basements and boundaries. Most of the founded anticlines can be regarded as superimposed bodies of two-level flower-structure borne in Mesozoic and lower Paleozoic, Their evolutionary history could be divided into three stages as pre-folding tension, primary folding and final forming.There are plenty of source rocks, reservoirs, and caprocks in lower Paleozoic, and the source-reservoir-caprock assemblages are abundant too, and different types of traps have been found in the studying area, most of which are structural traps.Almost all of the lower Paleozoic source rocks in south ease Sichuan basin are high-over evolved, which mainly produce gas. The complexity of petroleum system are indicated by the source providing, the bearing system, the pool-forming process, the system composition, the location of accumulation and other aspects. The petroleum system has characteristics of late accumulation and bulk sealing. The scale and location of gas pool are determined by geological structures, and the middle deformed areas are promising ones which should be regarded as targets of next exploration.更多还原