【作者】 李洁；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 沉积学， 2008， 硕士

【摘要】 鄂尔多斯盆地是一个大型的多旋回克拉通叠合盆地,构造上处于中国沉积盆地分布的中带,是我国天然气勘探的重点和最具勘探潜力的盆地之一,亦是“西气东输”的骨干资源基地之一。本论文以沉积学、高分辨率层序地层学、石油地质学的理论为指导,以鄂尔多斯盆地西北部下石盒子组为研究对象,系统开展下石盒子组沉积体系、高分辨率层序地层学和层序—岩相古地理研究,为鄂尔多斯盆地下石盒子组的进一步油气勘探提供重要的基础地质资料。根据区域沉积格局和沉积作用特点,将下石盒子组沉积体系划分为大陆沉积体系组,及其相应的冲积体系、湖泊三角洲体系和湖泊体系。研究表明区内存在东、西部两大河流—三角洲系统,结合盆地区域构造背景和沉积演化特征,以及研究区河流类型、腹地地势（坡度）、湖盆水体深度等控制因素,将研究区的三角洲识别为辫状河三角洲(盒_8下段、盒_8上段)和曲流河三角洲（盒₇段、盒₆段、盒5段）两种类型,并指出该类三角洲具有河控浅水型的特征,三角洲分流河道和水下分流河道砂体为骨架砂体,而河口坝、前缘席状砂及远砂坝不太发育。运用层序地层学理论对鄂尔多斯盆地西北部下石盒子组进行了高分辨率层序地层学研究,提出了适合研究区的地层层序划分对比标志,将下石盒子组划分为1个超长期旋回、5个长期旋回、10个中期旋回,建立了下石盒子组的地层层序划分系统和层序格架。并研究了下石盒子组层序发育特征、层序界面类型、体系域结构、不同级次旋回的类型和成因特征。在上述研究的基础上,运用层序—岩相古地理编图方法,以长期和中期旋回层序系统编制了下石盒子组层序—岩相古地理图。就其古地理及砂体展布特征,及其时空演化规律进行了详细的研究,表明研究区下石盒子组具有冲积—三角洲—湖泊沉积的古地理特征。更多还原

【Abstract】 Ordos Basin is a large multicycle craton superimposed basin, in the middle tectonic strip of sedimentary basin of china, an important basin with strong potential for natural Gas exploration, and one of the backbone resource bases for " West to East Gas Pipeline Project" .In this thesis, the article apply the basic theories and methods of Sedimentology, High-resolution sequence stratigraphy and Petroleum Geology to research the sedimentary system , high-resolution sequence stratigraphy and lithofacies paleogeography characteristic of Xiashihezi Formation north-west of the Ordos Basin, and offer important basic data to further gas exploration in the Xiashihezi Formation of the Ordos Basin.Based on sedimentary pattern and Characteristic, Xiashihezi formation was indentified as the Continental sedimentary system including alluvial depositional systems , lacustrine-delta depositional system and lacustrine depositional system. Obviously, two river-delta systems developed in the east and west respectively. According to regional tectonic setting and evolution of sedimentary of Basin, Combining with the dominated factors of the fluvial types, hinterland topography (slope), depth of water body .etc. It is concluded that the delta in this area belongs to braided delta(member 8 of xiashihezi formation) and meandering delta(member 5,6,7 of xiashihezi formation) , noting that the deltas have characteristics of river-shallow lake delta. Reservoir sand-bodies are distributary channel deposition and underwater distributary channel deposition, the micro facies such as bayou sand bars and front matting shaped sand-bodie and far sand bars are not well developed.This thesis reseached the high-resolution sequence stratigraphy of the Xishihezi formation in the northwest of Ordos Basin, summarized the sound markers of stratigraphic division and correlation, and built the high resolution sequence stratigraphic framework of Xishihezi formation. Consequently, one Super Long-term Sequence Cycle(SLSC) was indentified , and then , subdivided into five Long-term. Sequence Cycle(LSC) and 10 Middle-term Sequence Cycle(MSC) respectively. Furthermore, it went to study the characteristics and genesis of sequence boundary, systems tracts and sequences.On basis of the above research, using of the sequence-based lithofacies paleogeography mapping methods, drawing the maps of sequence-based lithofacies paleogeography within the long-term and middle-term sequence cycle, disclosing the character and evolvement of the lithofacies paleogeography and sand body spreading regularity of Xiashihezi Formation, show it’s paleogeography composed by alluvial depositional systems, lacustrine-delta depositional system and lacustrine depositional system.更多还原