175 / 2022-02-27 23:44:33

基于元素的混积细粒岩甜点储层沉积微环境分析 ——以吉木萨尔凹陷二叠系芦草沟组为例

Elements; Micro environment; Dessert; Lucaogou Formation; Jimsar Sag

The study of the depositional microenvironment of the mixed fine-grained rocks of the Permian Luchaogou Formation in the eastern Jimsar Sag of the Junggar Basin and its controlling factors on the dessert reservoir is not clear. The elements data were obtained by XRD/F on the basis of systematic observation of cores, and the paleoclimate, paleosalinity, palaeobathymetry, redox environment and paleoproductivity during its deposition period were analyzed and studied. The results show that. (1) the elemental contents of the upper sweet spot are more Mg and Ca, and the main elements of the lower sweet spot are Si, K and Al. Due to the variability of the sedimentary microenvironment, the upper sweet spot is dominated by feldspathic clastic sandstone, and the lower sweet spot is dominated by dolomitic siltstone and long-ingrained dolomite. (2) Elemental ratio analysis of Sr/Cu, Mg/Ca and Fe/Mn shows that both the upper and lower sweet spots were in hot and dry climatic environment during the deposition period, and the paleoclimate of the lower sweet spot was more arid and higher salinity than the upper sweet spot; the upper sweet spot is mainly saline lakes, relatively moist, with abundant rainfall and more development of feldspathic dolomite, mud crystal dolomite and lacustrine mudstone, which is more conducive to the development of shallow lakes . (3) The sedimentary period was dry and hot environment, due to the difference of rainfall and evaporation, which influenced paleosol depth, paleosalinity, redox environment and paleoproductivity, so that the Si, K and Al elements representing terrestrial debris and Mg and Ca elements representing carbonate rocks were distributed in the plane.