【作者】 李伟；

【导师】 周瑶琪； 吴智平；

【作者基本信息】 中国石油大学 ， 地质资源与地质工程， 2007， 博士

【摘要】 中生代渤海湾盆地区经历了复杂的地质发展史和严重的后期改造,且研究基础薄弱,在一定程度上严重制约了渤海湾盆地前第三系的油气资源评价与勘探。恢复中生代各构造期原型盆地格局,分析盆地的形成、演化及改造过程,并在此基础上研究不同构造期盆地的叠合关系是渤海湾盆地前第三系油气勘探的关键。依据不整合面的发育情况,将渤海湾盆地中生界自下而上划分为下-中三叠统、上三叠统、下-中侏罗统、上侏罗-下白垩统及上白垩统五个构造亚层,在此基础上对各构造亚层的发育及横向展布特征进行了研究。通过对中生代陆内周边造山带和深大断裂的形成演化以及深部动力学机制的研究,明确了中生代渤海湾盆地区发育演化的地球动力学背景。在此基础上,通过对地震测线的详细解释,采用断层活动速率方法对渤海湾盆地主要断裂的活动性进行了研究,确定了中生代主要活动的断层及其发育演化特征,并结合主要地震测线的平衡剖面恢复、伸展率分析及中生代不同构造期构造样式的研究,对渤海湾盆地区中生代构造发育特征进行了分析,进而将渤海湾盆地区中生代盆地演化划分为5个阶段:早-中三叠世为大型内陆沉积盆地;晚三叠世整体挤压抬升,遭受剥蚀;早-中侏罗世早期发育小型山间盆地,晚期为披覆式沉积;晚侏罗-早白垩世渤海湾盆地区以断陷盆地发育为主,并出现了分区性,发育有拆离断陷型、拉张断陷型、反转断陷型和走滑拉分断陷型四种类型的断陷盆地;晚白垩世盆地整体隆升剥蚀,仅在局部低洼地区接受沉积。在上述研究的基础上,结合新生代古近纪盆地的发育演化特征,对渤海湾盆地区中、新生代不同构造期盆地的叠合关系进行了研究,提出了盆地叠合单元的概念,将渤海湾盆地划分为3大类6小类叠合单元并进行了平面区划。在上述研究的基础上,对渤海湾盆地前第三系石油地质条件进行了分析,对不同类型叠合单元的典型区块进行了实例解剖,总结归纳了各类型叠合单元前第三系石油地质条件的差异性并从叠合单元区划的角度对渤海湾盆地前第三系有利勘探区块进行了预测:(1)古生界有利勘探区块,以Ⅱ2、Ⅱ4型叠合单元最为有利,若Ⅰ型叠合单元侏罗-白垩系沉积较薄且后期改造程度较弱也较为有利;(2)中生界有利勘探区块,以Ⅰ、Ⅱ2型叠合单元最为有利,若Ⅱ3型叠合单元在中生代末期已进入大量生排烃门限且后期改造程度较弱、中生界内部发育有良好的储盖组合也较为有利。更多还原

【Abstract】 The Mesozoic basin of Bohai Bay basin experienced complicated geological development and serious reconstruction, and the research foundation is unsubstantial, that restricts the resources assessment and the exploration of the pre-tertiary oil and gas of Bohai Bay basin to some extent. So the restoration of the prototype basin of each structural period in Mesozoic, and the analyzing of the forming, evolution and the reconstruction, furthermore making certain the superimposition relationship of each structural period basin is the key to the exploration of the pre-tertiary petroleum of Bohai Bay basin.According to the unconformities, the Mesozoic of Bohai Bay basin can be divided into five structural sub-layers: lower to middle Triassic, upper Triassic, lower to middle Jurassic, upper Jurassic to lower Cretaceous, upper Cretaceous, then the characteristics of the lithology and the distribution were ascertained. Through the research on the evolution of the terrestrial peripheral orogenes, the deep faults and the geodynamics mechanism in Mesozoic, the geodynamics background of the basin evolution in Mesozoic were ascertained. On the basis of above analysis, through the detailed interpretation of the seismic sections, the activities of the main faults in Bohai Bay basin were studied using the fault activity velocity, and the development characteristics of the Mesozoic faults were ascertained. Furthermore, combined with the analysis of balanced cross section, extension ratio and the structural style of each structural period in Mesozoic, the Mesozoic structural characteristics in the area of Bohai Bay basin were analyzed. On the basis of above research, the Mesozoic basin evolution in the area of Bohai Bay basin can be divided into five periods: early to middle Triassic, a large-scale interior basin; late Triassic, the area of Bohai Bay basin was extruded and uplifted undergoing denudation; early to middle Jurassic, some small intermontane basin developed in the earlier period, from the middle to later period the drape-like deposition developed; late Jurassic to early Cretaceous fault basin developed mainly, various types of basin developed in various area, such as detachment rift, extension rift, inversion rift and strike-slip and pull-apart rift; late Cretaceous, the area of Bohai Bay basin uplifted wholly, only deposited in few lower area. Combined with the evolution in Paleogene, the superimposition relationship of each structural period in Mesozoic and Cenozoic were ascertained, the superimposition unit were defined in this thesis. Bohai Bay basin can be plot out into three large kinds and six small kinds of superimposition units. On the basis of above research, analyzed the petroleum conditions of pre-tertiary, studied the petroleum conditions of different kinds of superimposition, the difference of petroleum conditions of pre-tertiary of different kinds of superimposition units were summarized. Finally, the advantageous exploration areas were brought out on the side of the plot of the superimposition units: for Paleozoic, the superimposition units ofⅡ2 andⅡ4 are best, the superimposition ofⅠis better in case the Jurassic and Cretaceous deposited thinly and the reconstruction later was weak; for Mesozoic, the superimposition units ofⅠandⅡ2 are best, the superimposition ofⅡ3 is better in case the source rocks had come into the hydrocarbon-generation threshold, the reconstruction later was weak and the combination of reservoir and cap rocks was good.更多还原