四川盆地高石梯—磨溪地区震旦系—寒武系天然气的地球化学特征及成因

发布时间：2018-08-13 13:04

【摘要】：根据天然气组分、稳定碳同位素和氢同位素等地球化学资料,对四川盆地高石梯—磨溪气田震旦系—寒武系天然气地球化学特征进行分析。结果表明:1震旦系、寒武系天然气均以甲烷为主,重烃含量偏低而非烃含量较高,为典型的干气;2研究区天然气热演化程度较高,震旦系天然气中部分乙烷发生裂解,导致残余天然气的δ13C2变重;3研究区天然气以正碳同位素序列为主,仅部分寒武系天然气的碳同位素序列发生局部倒转,可能是高热演化阶段下同源不同期气或同型不同源气混合所致;4氢同位素显示,震旦系沉积环境的水介质盐度高于寒武系,且震旦系天然气为震旦系烃源岩和寒武系烃源岩的混源气,而寒武系天然气母质来源为寒武系烃源岩。
[Abstract]:Based on the geochemical data of natural gas components, stable carbon isotopes and hydrogen isotopes, the geochemical characteristics of natural gas from Sinian to Cambrian in Gaoshiti-Moxi gas field in Sichuan Basin are analyzed. The results show that in the Sinian, the Cambrian natural gas is mainly methane, the heavy hydrocarbon content is lower than the non-hydrocarbon content, the thermal evolution degree of the natural gas in the typical dry gas study area is high, and some ethane in the Sinian natural gas has been cracked. In the 未 13C2 gravimetric area of residual natural gas, the natural gas is dominated by positive carbon isotopic sequence, only partial carbon isotope sequence of Cambrian natural gas is locally reversed. It is suggested that the salinity of water medium in the sedimentary environment of Sinian is higher than that in Cambrian, which may be caused by the mixing of homologous and heterogeneous gases or different homologous gases at high thermal evolution stage. Sinian natural gas is mixed source gas of Sinian source rock and Cambrian source rock, while Cambrian natural gas source rock is Cambrian source rock.
【作者单位】：中国科学院大学渗流流体力学研究所;中国石油天然气集团公司天然气成藏与开发重点实验室;甘肃省地质矿产勘查开发局第三地质矿产勘查院;中国石油华北油田勘探开发研究院;中国石油青海油田勘探开发研究院;
【基金】：国家科技重大专项“大型气田形成条件、富集规律及目标评价”(编号:2011ZX05007)
【分类号】：P618.13

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