威远构造气烟囱特征及其形成机理

发布时间：2018-05-21 12:46

本文选题：四川盆地 + 威远构造　；参考：《成都理工大学》2017年硕士论文

【摘要】：作为中国天然气工业的摇篮,威远构造灯影组气藏(威远气田)的勘探对新中国初期的现代化天然气工业的发展做出了重要的贡献。威远构造是四川盆地规模最大的地表构造,但其灯影组气藏充满度相对较低,含气高度244m,综合充满度仅26.3%。对其原因,相关研究较少且并未取得一致认识。经过近四十年的不断勘探,2011年邻区高石1井(高石梯-磨溪构造)灯影组获高产天然气;次年8月,在磨溪8井在寒武系龙王庙组同样获高产气流,从此揭开了四川盆地下古生界自1964年威远气田勘探成功后又一个重大发现,研究表明威远构造和高石梯-磨溪构造灯影组生储盖组合接近相似,高石梯-磨溪构造灯影组却为充满度近似100%的特大型整装气田。结合威远构造实际地质条件与国内外油气运移、气烟囱等相关研究实例,依靠地表与地腹资料,地质-地球物理-地球化学综合研究方法,对气藏低充满度做出了合理解释。(1)威远构造为现今四川盆地除川东高陡构造外灯影组最高点,广安→龙女寺→磨溪→高石梯→威远构造为喜马拉雅期在区域隆升过程中形成的圈闭闭合度、溢出点海拔逐渐抬高的灯影组系列圈闭。四川盆地灯影组天然气存在大范围长距离的差异聚集。(2)威远地区在40Ma左右抬升形成现今构造,为四川盆地内地表除川东高陡构造外唯一出露三叠系嘉陵江组、雷口坡组的区域。隆升剥蚀作用造成在威远构造核部形成了灯影组天然气逸散的“天窗”。气烟囱存在证据包括:(1)非烃气体组分含量:组分百分比自下而上呈缓慢递减趋势;(2)压力系数:威远构造底部灯影组气藏至最上部二叠系含气层均为常压;(3)同位素地球化学:最具深源无机成因特征的Ar气在上部二叠系其Ar~(40)/Ar~(36)比值仍高达2 855~5 222。气烟囱效应特征明显。威远构造气烟囱表明,现今盆地尺度内灯影组天然气长距离运移、调整和逸散过程仍在进行,四川盆地灯影组气藏仍处在动态成藏过程中。这一模式的关键是威远地区隆升剥蚀与挤压变形,在构造核部形成了天然气逸散的“天窗”,使威远构造成为四川盆地中西部区域灯影组天然气逸散的主要通道。
[Abstract]:As the cradle of China's natural gas industry, the exploration of Weiyuan structure Dengying formation gas reservoir (Weiyuan gas field) has made an important contribution to the development of modern natural gas industry in the early stage of New China. Weiyuan structure is the largest surface structure in Sichuan basin, but the gas filling degree of Dengying formation gas reservoir is relatively low, the gas bearing height is 244 m, and the comprehensive filling degree is only 26.3%. There is little research on the causes and no consensus has been made. After nearly 40 years of continuous exploration, the Dengying formation of Gaoshi No. 1 well (Gaoshitian-Moxi structure) in the adjacent area obtained high natural gas in 2011, and in August of the following year, in Moxi well 8, it also obtained high gas flow in the Cambrian Longwangmiao formation. From then on, another important discovery of the Lower Paleozoic in Sichuan Basin since the successful exploration of Weiyuan gas field in 1964 shows that the Weiyuan structure is close to the assemblage of source, reservoir and caprock of the Dengying formation of Gaoshitian-Moxi structure. The Dengying formation of Gaoshi-Moxi structure is a super-large gas field with a full capacity of about 100%. Combined with the actual geological conditions of Weiyuan structure and related research examples of oil and gas migration and gas chimney at home and abroad, based on the data of the earth's surface and the earth's web, the comprehensive research method of geology, geophysics and geochemistry is used. The Weiyuan structure is the highest point of Dengying formation except for the high and steep structure in Sichuan basin. The Kuang'an Longnu Temple is a series of traps of Dengying formation, which is formed in the Himalayan period during the regional uplift, and the overflow point is gradually elevated in the Dengying formation. The natural gas of Dengying formation in Sichuan basin has a large range and long distance differential accumulation. The Weiyuan area is uplifted around 40Ma to form the present structure, which is the only area of Triassic Jialingjiang formation and Leikoupo formation in the inland surface of Sichuan basin except for the high steep structure in eastern Sichuan. The uplift and denudation resulted in the formation of a "skylight" of natural gas dissipation in the Weiyuan tectonic nucleus. Evidence of existence of gas chimney includes: 1) content of non-hydrocarbon gas components: the percentage of components is decreasing slowly from bottom to top; pressure coefficient: gas reservoir of Dengying formation at the bottom of Weiyuan structure to upper Permian gas reservoir are atmospheric pressure Jiao 3) isotopes Geochemistry: in the upper Permian, the ar gas with the characteristics of the most deep-source inorganic origin is still as high as 2855 / 5222. The characteristic of gas chimney effect is obvious. The Weiyuan structural gas chimney shows that the gas of Dengying formation is in the process of long distance migration, adjustment and dissipation in the present basin scale, and the gas reservoir of Dengying formation in Sichuan basin is still in the process of dynamic reservoir formation. The key of this model is uplift, denudation and compression deformation in Weiyuan area. The "skylight" of natural gas dissipation is formed in the structural core, which makes Weiyuan structure become the main channel of natural gas dissipation of the Dengying formation in the central and western Sichuan basin.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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