【作者】 隆轲；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 沉积学， 2010， 硕士

【摘要】 近年我国的海相油气勘探在四川、塔里木等取得了一些重要突破和发现。黔南桂中地区石炭系为中国南方海相地层发育最好的地区之一,为了弄清研究区到底有不有勘探潜力以及勘探方向,因此本论文通过对黔南桂中地区石炭系地层系统、沉积体系特征、层序地层、层序岩相古地理特征及演化和层序格架中的储层特征的研究,为勘探提供依据,取得了以下几点认识:根据最新的岩石地层和区域地质志,按不同坳陷和不同沉积区厘定了研究区石炭系地层,并进行了对比。在沉积学和岩相古地理工作方法的理论的指导下,通过基干剖面的实测、辅助剖面的观测和钻井资料的研究,根据岩石类型、岩性组合、剖面结构和沉积构造,在研究石炭系共识别出了4种沉积体系,分别是海岸沉积体系、碳酸盐台地沉积体系、台盆沉积体系和陆棚沉积体系,同时划分了相应的沉积相、亚相和微相。总的来看,研究区表现出由北到南为古陆→滨岸→陆棚→碳酸盐台地→台盆与台地相互交错的沉积相带变化趋势,并建立了沉积模式。对黔南桂中地区石炭的层序界面特征及成因类型进行了详细研究,共识别出古风化壳、大气淡水作用面、岩性岩相转换面、最大海泛面等层序界面。在层序界面识别的基础上将石炭系划分出2个超层序,11个三级层序,详细讨论各超层序及三级层序的体系域特征及层序特征,并对研究区的三级层序进行了对比,三级层序在研究区皆可以对比。在层序划分和对比的基础上,以超层序体系域为编图单元,采用体系域压缩法编制了5张黔南桂中地区石炭纪构造—层序岩相古地理图,揭示了黔南桂中地区石炭纪岩相古地理特征。SS1低位期,紫云运动造成研究区大部分地区暴露,黔南主要发育陆棚和局限台地,桂中地区为台盆和台地相间的沉积格局;SS1海侵期,海平面快速上升,黔南发育滨岸沉积,桂中地区台盆范围扩大;SS1高位期古地理格局变化不大,由于海水下降,台地扩大,台盆缩小;SS2构造运动减弱,古地理格局发生明显变化,海侵期仍以台地和台盆沉积为主,台盆被充填萎缩,变得狭窄,台地范围变大,SS2高位期由于石炭世末的黔桂运动造成黔北和黔中地区隆起成陆,海水向南退缩,台盆范围继续变小,呈现台包盆格局。基于储层孔隙类型和物性分析,研究区储层为上石炭统大埔组和黄龙组台地相的白云岩和生物碎屑灰岩,均属于低孔低渗储层,其中大埔组的物性好于黄龙组。储层主要发育于高位体系域中,高位期海平面下降,引起台地相中的白云岩、生物礁灰岩的暴露和溶蚀形成大量的溶蚀孔洞。更多还原

【Abstract】 Recent years China’s marine hydrocarbon exploration has achieved some significant breakthrough and discoveries in Sichuan Basin and Tarim Basin. Carboniferous of South Guizhou and Middle Guangxi is one of best developed areas for marine stratum, to figure out whether there is exploration potential or not and the exploration direction, so this thesis focuses on Carboniferous stratum system, depositional system characteristic, sequence stratigraphy, characteristic and evolution of sequence lithofacies paleogeographic and reservoir characteristic within sequence framework in South Guizhou and Middle Guangxi, which can provide some exploration proofs. Several achievements have gained as follow.According to the latest rock stratigraphic and regional geology, the Carboniferous stratum has been regularized in different sedimentary area of different depression, and they has been contrasted.Guided by the theories of sedimentology and the work methods of lithofacies paleogeographic, and based on measurement of main field geological sections, observation of supplementary field geological sections and data of drilling, according to types of rock, combination of rock, section character and sedimentary structure, four depositional systems are distinguished in Carboniferous of study area, they are coastal depositional system, carbonate platform depositional system, platform basin depositional system and shelf depositional system, meanwhile the depositional facies, subfacies and microfacies were divided. Taking one with another, the depositional facies belts was kind of old land-shore-shelf-carbonate platform-platform basin interleaved with platform. The depositional models have also been established. After detailedly study on Carboniferous sequence boundary characteristic and genesis types in South Guizhou and Middle Guangxi, the sequence boundaries, paleocrust of weathering, atmospheric water effect surface, lithology and lithofacies transitional surface and maximum flooding surface, were identified. Based on the sequence boundary identification, Carboniferous can be divided into 2 super sequence and 11 third-order sequence, the system tracts and sequence characteristic of each super sequence and third-order sequence were carefully discussed, and the third-order sequence was contrasted in study area, which are comparable in study area.Based on sequence division and contrasting, taking system tracts of super sequence as compilation unit and using system tracts compression method, five Carboniferous tectonic-sequence lithofacies paleogeographic in South Guizhou and Middle Guangxi were drew, which can show the Carboniferous paleogeographic character of study area. During SS1 lowstand period, Ziyun movement caused the exposure of most parts of study area, shelf and restricted platform developed in south Guizhou, and it showed the sedimentary pattern of platform basin interleaved with platform in Middle Guangxi, then to transgression period, sea level rose quickly, shore developed in South Guizhou, platform basin expanded in Middle Guangxi, during highstand period, the paleogeographic pattern changed little, platform expanded, platform basin shrunk. Then in SS2 stage tectonic movement became weaken, the depositional facies pattern changed a lot. During transgression period, the sedimentary facies mainly were platform and platform basin, platform basin was filling and shrunk continuously, and platform range continued to expand. Finally during SS2 highstand period, due to the Qiangui movement in late of Carboniferous, north and middle Guizhou rose to be land, sea retreated forward south, platform basin shrunk continued, it showed the depositional pattern of basin surrounding by platform.By analysis of pore type and physical property of reservoir, the main reservoir of study area is dolomite and biodetritus limestone in platform of Dabu Formation and Huanglong Formation, which all are reservoir of low porosity and low permeability, the physical property of Dabu Formation is better than the one of Huanglong Formation. Reservoir mainly developed in highstand system tracts, as the fall of sea level, the exposure and erosion of dolomite and biodetritus limestone in platform formed a large number of solution cave.更多还原