【作者】 曾春林；

【导师】 姜波；

【作者基本信息】 中国矿业大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 本论文在前人对柴达木盆地北缘石油地质综合研究的基础上,系统整理和分析区域地质及柴北缘相关地质资料,剖析柴北缘侏罗系沉积分布和演化与区域构造背景的耦合机理,确定了侏罗系烃源岩在燕山期和喜马拉雅期的构造-沉积格局和埋藏特征。结合测试分析和前人资料,揭示了柴北缘中生代以来古地温梯度的总体演化趋势,研究了柴北缘侏罗系烃源岩生烃作用演化历史,分析和研究不同性质的构造演化及其组合特征对沉积和油气的控制作用,揭示了侏罗系烃源岩有利生烃的地域、时域、深度和相态,为油气地质勘探提供依据。柴达木盆地北缘(以下简称柴北缘)位于柴达木盆地东北部,红山以西是此次工作的研究范围,即柴北缘西段。柴达木盆缘的构造发育、组合型式、空间展布、规模大小和变形特征等虽然各有差异,但具有许多相似之处,其中最显著的特征是以压性或压剪性构造为主。从基底的形态来看,柴北缘主要受到NWW-NW、NE-NNE和近NS向三组断裂的控制,形成了东西分段、南北分带且隆凹相间的构造格局。盆地边缘的阿尔金造山带、祁连造山带和东昆仑造山带,其构造演化在成因机制上与周边板块构造运动具有有机的联系,同时又对盆地构造的演化具有极其重要的控制作用。经过研究区主干地震测线的构造解释及实验测试结果分析,结合区域构造背景,将柴北缘的构造演化分为早-中侏罗世的断坳盆地、晚侏罗世-白垩纪的坳陷盆地、白垩纪末期的挤压抬升剥蚀、古近纪坳陷盆地和新近纪挤压坳陷盆地5个大的演化阶段。柴北缘侏罗系主要是在造山期后的伸展作用及自身的沉积载荷下沉积的,其构造的复杂性主要是后期构造旋回叠加和改造的结果。受构造活动的控制,柴北缘侏罗系沉积中心具有由SW向NE迁移且沉积范围不断萎缩的特点。柴北缘侏罗系烃源岩自沉积以来,经历了2期构造-深埋作用,分别发生在燕山期和喜马拉雅期。在平面上,各构造带之间埋藏时代和埋藏深度存在一定差异,致使烃源岩成熟演化存在明显不同,多数地区普遍只发生一次生烃演化,仅有少部分地区发生二次生烃。喜马拉雅期(E3-N1),烃源岩埋藏深度大,成熟度高,是最主要的生烃期。燕山期和喜马拉雅期构造活动控制了侏罗系烃源岩的沉积、圈闭形成、油气运移通道的形成,这些因素在时间和空间上的合理配置,便形成了柴北缘现有的油气藏。通过研究,认为控制柴北缘油气成藏的关键因素是生烃中心和构造活动。生烃中心确定了油气田的分布范围;构造活动也能破坏油气藏,使浅部油气藏会沿着破碎带逸散到地表。故应在生烃中心附近寻找构造相对稳定的区域作为勘探的目标。更多还原

【Abstract】 Based on the comprehensive research on petroleum geology in the northern margin of Qaidam basin, this paper analysed the regional geology, the coupling mechanism between Jurassic strata and regional structure, and established the tectonic-sedimentary and buried characteristics. Combining with tests and data, the paper revealed the trend of temperature gradient, and the hydrocarbon generation evolution of Jurassic source rocks; at the same time, we studied the tectonic evolution and its control over sedimention and oil-gas, revealing the region, time, depth and phase which were benefical to hydrocarbon generation. All these can be considered in oil and gas exploration.Research area is located in the northeast of Qaidam basin, that is, west of Hongshan. The tectonic development, combination form, distribution, scale and deformation characteristics are various in different areas, but there are some common grounds, compressional structure (compression-shear) is the main character. The area formed the tectonic framework of uplift and depression interphase from the basement, which was controlled by the three groups of faults with strike of NWW-NW, NE-NNE and nearly NS. The evolutions of Altyn fault belt, Qilian orogenic belt and east Kunlun orogenic belt are related to surrounding plates movement, and all the 3 orogenic belts controlled the evolution of the basin.Based on the analysis of seismic sections, results of tests and regional tectonic setting, tectonic evolution of Mesozoic and Cenozoic is divided into five stages: fault sag stage in early- middle Jurassic; depression stage in late Jurassic– Cretaceous; uplift-erosion stage in late Cretaceous; depression stage in Paleogene; squeezed sag in Neogene. Controlled by the extension of and postorogenic phaseand self sedimentary loading, the Jurassic was formed, but the complexty of structure was the result of later activities and reformation. The depocenter atrophied and transferred from SW to NE controlled by structure activities.Since deposition, Jurassic source rocks have experienced two stages of tectonic and burial history, which were Yanshan stage and Himalayan stage. Different buried stage and depth lead the difference of hydrocarbon generation evolution in various structure belts, most of areas have one hydrocarbon generation stage, and only some have two. The Himalayan stage (E3-N1) with great depth and high maturity of source rocks is the main hydrocarbon generation stage.The activities of Yanshan stage and Himalayan stage controlled the sedimention of Jurassic sourcks, formation of traps and migration channels, which formed the reserviors based on the rational allocation of time and space. Based on the research, we can see that hydrocarbon generation center and structure avtivities are the key factors which control the reservoirs. Hydrocarbon generation center determined the scale of oil field; structure avtivities can destory the reservoirs and lead the oil-gas dissipation. Therefore, the relatively stable structure area near the Hydrocarbon generation center could be the best exploration target.更多还原