【作者】 刘喜顺；

【导师】 郭建华；

【作者基本信息】 中南大学 ， 矿物学、岩石学、矿床学， 2009， 博士

【摘要】 海相碳酸盐岩地层油气资源非常丰富,自然界中有近50%的油气资源富集于碳酸盐岩地层中。中国南方陆上有近200×104km2的碳酸盐分布区,具有碳酸盐岩分布面积大、层系多、厚度大、分布广的优势和广阔的勘探前景,是实现我国“能源战略”的重要战略接替区。针对湘中拗陷高演化的特点,本文以油气成藏理论为基础,应用层序地层学、构造地质学、碳酸盐岩沉积学、岩石学、储层地质学及地球化学等多学科的理论为指导,深入研究了泥盆-石炭系油气成藏及保存条件,初步理顺了区内构造与沉积演化、烃源岩热演化、油气藏的形成、破坏、再次成藏及晚期成藏的配置关系,以油气藏保存条件为重点,应用含油气保存单元的评价体系对湘中拗陷进行有利区带划分,提出了下步有利勘探目标区,为后继油气勘探工作提供决策依据。以涟源凹陷为重点,深入分析了油气成藏条件。研究了“下组合”的成藏优势。认为构造变形的强度、幅度及沉积相的组合关系是控制天然气富集的主要因素。湘中地区勘探成果和典型气藏解剖结果表明,构造变型较弱、幅度较小的地区天然气保存条件较好,在这些地区槽、台相区之间的斜坡带及滩礁沉积相带是油气藏形成和保存最有利的区域。在综合考虑构造样式和油气的生成、运移、成藏的各个条件基础上,划分出Ⅰ、Ⅱ、Ⅲ级远景区,涟源凹陷中部为Ⅰ级远景区,邵阳凹陷中东部、涟源、零陵凹陷东部为Ⅱ级远景区,其它地区为Ⅲ级远景区,在Ⅰ级远景区优选了杨家山区块、桥头河区块为近期突破靶区。与前人认识相比,本文在以下几个方面显示出一定的特色与创新：(1)应用Vail的经典层序地层学原理和方法,通过野外剖面踏勘和钻井资料的详细研究,首次在泥盆系识别出1个Ⅰ型层序界面和9个Ⅱ型层序界面,结合前人石炭系层序地层学的研究成果,将湘中地区泥盆-石炭系划分为三个Ⅱ级层序和21个Ⅲ级层序。(2)对湘中拗陷生物礁与台盆相的发育规律及相互关系做了深入研究,首次提出泥盆系棋梓桥组与佘田桥组中的生物礁是成带分布的,台盆可能是由于生物礁的快速生长而形成的礁间洼地(礁间槽)。因此,礁间槽的形成、发展与消亡和生物礁带的形成演化关系密切相关。这一模式与现代澳大利亚大堡礁具有很好的可比性。(3)湘中坳陷发育在汇聚型板块边缘,是两个大的陆块碰撞结合部位,构造样式较为复杂。从整体上看,整个工区的关键性构造要素是犁式叠瓦状逆冲断层、紧闭线性褶皱和隔挡式褶皱。结合遥感、航磁、重力等资料,重点对涟源凹陷做了深入研究,将凹陷进一步划分为西部断褶带(西部构造带)、中部褶皱带(中部构造带)和东部褶断带(东部构造带),并探讨了不同构造带的构造样式和形成机制。(4)提出对圈闭有效性研究的方法,指出构造样式、生储盖组合的配置关系及圈闭形成与烃源岩演化的匹配性都是影响圈闭有效性的主要因素,认为保存条件是决定圈闭有效性的首要条件,是决定其勘探价值的首要因素。湘中海相地层经历了印支期后多期、多方式构造运动的改造,具有隆坳相间、背向斜相间出现的特点,稳定的负向构造单元及测水煤系地层的分布区是油气保存的有利地区,在相对稳定的负向构造单元的有效区域盖层分布区主要寻找两类圈闭,即：台滩或台坪相岩性或岩性与构造复合圈闭和断背斜构造圈闭两大圈闭类型。(5)结合流体包裹体均一温度分析和构造演化研究的认识,对湘中拗陷烃源岩的演化和生烃模式的认识取得突破。流体包裹体均一温度分析研究表明,湘中拗陷烃源岩有3次主要的生排烃过程,并建立了“三段生烃”及裂解生气的“四段式”生烃模式。更多还原

【Abstract】 Hydrocarbon resources are very rich in marine carbonate rocks. In nature, about 50% hydrocarbon resources accumulated mainly in carbonate rocks. In the southern land of China, there are almost 200x104km2 carbonate rocks distribution area, with a great predominance of large carbonate rocks area, multiple layer systems, great thickness, widespread distribution and abroad exploration prospect, which is a very important base of energy strategic in China.According to the high evolution characteristics in Xiangzhong basin, the article was based on the hydrocarbon accumulation theory, in pride of multiple theory, such as the sequence stratigraphy, structural geology, carbonate sedimentology, lithology, reservoir geology and geochemistry, and thoroughly studied the reservoir-forming mechinsm and preservation conditions of Devonian-Carboniferous, preliminarily straightened evolution of tectonics and sediments, thermal evolution of source rocks, match relations among reservoir formation, destruction, second accumulation and late accumulation, emphasized reservoir preservation conditions, applied evaluation system of hydrocarbon-bearing preservation units to divide expect area in Xiangzhong basin, proposed favorable exploration target area which provides decisions referenec for subsequent exploration works.Especially in the Lianyan depression, reservoir forming conditions have been analysized intensively. The article investigated reservoir forming advantages of "low combination" system. It was considered that the main factors of controlling gas enrichment area are tectonic deformation intensity, scope and sedimentary system. Exploration results and analysis on typical gas reservoir shows that the area where the tectonic deformation is weak, and movement is slightly, gas preservation conditions are fairly good; and that reef-shoal sedimentary belts and ramp region between geosynclinal and platform areas are favorable areas of oli and gas reservoir forming and preservation.Based on general study, inclouding structural patterns and conditions of hydrocarbon generation, migration, accumulation,Ⅰ,Ⅱ,Ⅲprospects area are divided:I-the middle Lian Yuan depression,Ⅱ-the middle and east of ShaoYang depression, the east of Lian Yuan and Ling Ling depression,Ⅲ-other regions. In prospect I, the block of Yang Jia mountain and QiaoTou river are recently targets for breakthrough of petroleum exploration.Compared with predecessors’ cognitions, the article has some characteristics and innovations in the following aspects:(1).Applying the principles and methods of Vail prime sequence stratigraphy, and in pride of profile exploration out-door and well drilling data,one sequence interface of I type and 9 sequence interfaces ofⅡtype were marked out first time in Devonian. Referening to the sequence stratigraphy of predecessors’ cognitions in Carbonate,Devonian-Carbonate in the Xiangzhong basin was divided into 3 sequences of II degree and 21 sequences ofⅢdegree.(2). Development rules and interrelation of reefs and platform basin facies in Xiangzhong basin are studied thoroughly. And the viewpoints was proposed firstly that reefs of Devonian Qiziqiao and Shetianqiao formation are distributed in belts and platform basin may be inter-reef synclines formed by rapid growth of reef. In sequence, the formation, development and extinction of inter-reef synclines was closely correlate with formation and evolution of reef belts. This pattern has good comparability with modern Australian Great Barrier Reef. (3).The Xiangzhong basin developed in convergent plate boundary which is the binding site of two large collision blocks. And its structural patterns are very complex. As a whole, the key structural elements of the whole section are plough imbricate thrusts, closed linear folds and ejective folds. Connected with data of remote sensing, aeromagnetic and gravity, Lian Yuan depression was studied and divided into the west fold belt, the middle fold belt (the middle structural belt) and the east fold belt (the east structural belt). And the structural patterns and formating mechanism of different structural belts were discussed in the article.(4). The article proposed methods of trap efficiency study, and pointed out that match relations between source-reservoir-cap assemblage and structural patterns and the matching of trap formation and source rocks evolution are the firstly conditions of trap efficiency and dominate factors in determining exploration value. Marine layers in Xiangzhong basin experienced polyphase, multimode structural movements of late Indosinian. And their had features of inter-appearance of rise-and-depression, anticline-and-syncline. The stable negative elements and distributed area of hydrometric coal measure strata are favorable areas of oil and gas preservation. In the caprock distributed area of favorable areas of the stable negative elements, two kinds of traps are searched:traps of platform beach or platform terrace or complex lithology and structure,fault anticline structural traps.(5). Connected with analysis on homogeneous temperature of fluid inclusion and study of structural evolution, cognition on evolution of source rocks and hydrocarbon generating patterns has obtained the important breakthrough. The analysis on homogeneous temperature of fluid inclusion shows that, the source rocks in Xiangzhong basin had 3 major hydrocarbon generation and expulsion processes, and the "four-section hydrocarbon generation" model was set up, served as "triple-section hydrocarbon generation" stage and cracked gas generation stage.更多还原