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本文根据含油气系统理论 ,采用气藏地球化学方法 ,研究了四川盆地东部石炭系天然气成藏的地球化学模式。应用储层沥青中的芳香烃馏份进行了川东石炭系与志留系和下二叠统碳质页岩的特征对比 ,证实了石炭系的储层沥青与下志留统亲缘关系密切。石炭系地层水和储集岩经历了沉积、暴露剥蚀和深埋藏三个演化时期 ,天然气主要经历了大致相同的两次成藏过程 ,印支—燕山期为古油藏的主要成藏期 ,喜山期为天然气的主要成藏期。应用天然气地球化学特征探索了石炭系天然气的运移方向 ,提出了川东地区注入时间较早的气藏有大池干井、高峰场、相国寺和大天池等 ,其他气藏相对较晚 ,其中大池干井构造天然气的注入顺序依次为万顺场、吊钟坝、龙头和磨盘场。目前研究表明 ,石炭系天然气存在 3个运移方向 ,即开江古隆起西部由南西向北东和由西向东两个方向 ,开江古隆起东南部则可能有石柱复向斜方向运移来的天然气。指出石炭系天然气的聚集受开江印支—燕山期古隆起的控制 ,喜山运动形成的圈闭对天然气成藏具有调整作用 ,从气藏地球化学角度提出了下步勘探较为有利的区块 ,对深化石炭系勘探具有指导意义
Based on the petroleum system theory and geochemical method of gas reservoir, this paper studies the geochemical model of hydrocarbon accumulation in the Carboniferous natural gas in the eastern Sichuan Basin. The characteristics of Carboniferous in eastern Sichuan and Carboniferous shale in the Silurian and the Lower Permian are compared using aromatic hydrocarbon fractions from reservoir bitumen, confirming that the Carboniferous reservoir bitumen is closely related to the Lower Silurian. Carboniferous formation water and reservoir rocks have undergone three evolutionary stages of sedimentation, denudation and deep burial. Natural gas mainly underwent roughly the same two processes of accumulation. The Indosinian-Yanshanian period was the main accumulation period of paleo-oil reservoirs, Himalayan period is the main period of gas accumulation. The gas migration direction of Carboniferous is explored by using the geochemical characteristics of natural gas. It is proposed that the reservoirs with the earlier injection time in East Sichuan include Dachi dry well, Gaofeng field, Xiangguosi and Daytianchi, and other gas reservoirs are relatively late, in which Dachi dry well structure of natural gas injection sequence, followed by Wanshunchang, bell dam, tap and mill market. The current study shows that there are three migration directions of Carboniferous natural gas, that is, the westward of Kaijiang paleouplift from southwest to north and east to west, and the southeast of Kaijiang paleouplift may have the direction of the syncline migrating to Gas It is pointed out that the accumulation of natural gas in Carboniferous is controlled by the paleo-uplift of the Kaijiang-Indo-Yanshanian Period. The traps formed by the Himalayan movement play an adjusting role in the gas accumulation. From the gas geochemistry of the reservoir, the favorable blocks for further exploration are proposed , Which is instructive for deepening exploration of Carboniferous