鄂尔多斯盆地大牛地气田上古生界致密气轻烃地球化学特征

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中文摘要：大牛地气田是鄂尔多斯盆地典型致密砂岩大气田之一.为了更深入了解该区天然气的成因和来源,揭示天然气运移相态,对大牛地气田上古生界致密气开展了轻烃地球化学特征分析.研究表明,该区上古生界致密气C5-7轻烃组成具有异构烷烃优势分布,C6-7轻烃组成中芳烃含量整体偏低(＜10%),甚至未检出芳烃,C7轻烃组成具有甲基环己烷优势分布特征,甲基环己烷相对含量均超过 50%.上二叠统下石盒子组天然气K1值、K2值均与二叠系山西组和石炭系太原组天然气一致,而δ13C1值则与山西组天然气一致,与太原组天然气有明显不同.与山西组天然气相比,下石盒子组天然气整体具有偏低的苯/正己烷、苯/环己烷和甲苯/正庚烷比值,以及明显偏高的正庚烷/甲基环己烷比值.轻烃地球化学特征及烷烃气碳氢同位素组成综合表明,大牛地气田上古生界天然气为典型煤成气,其中山西组和太原组天然气均为原地自生自储,而下石盒子组天然气为下伏山西组烃源岩生成的天然气经历了游离相垂向运移聚集形成,太原组烃源岩不具有显著贡献.受天然气运移和水溶等作用影响,庚烷值、异庚烷值、苯/正己烷比值等轻烃指标直接用于判识大牛地气田致密气成熟度会存在偏差.

外文标题：Geochemical characteristics of light hydrocarbons in Upper Paleozoic tight gas from Daniudi Gas Field,Ordos Basin

外文摘要：The Daniudi Gas Field is one of the typical tight sandstone gas fields in the Ordos Basin.In order to better understand the genetic types and source of natural gas and reveal the migration phase of natural gas,the geochemical analysis of light hydrocarbons in the Upper Paleozoic tight gas from the Daniudi Gas Field has been conducted in this study.The results indicate that,the C5-7 light hydrocarbons in the Upper Paleozoic tight gas are dominated by iso-alkanes,and the C6-7 light hydrocarbons display low contents of aromatics(＜10%),which are even undetectable.The C7 light hydrocarbons are dominated by methylcyclohexane(MCH)with the relative MCH contents exceeding 50%.The K1 and K2 values of natural gas from the Lower Shihezi Formation(P1x)are consistent with those from the Shanxi(P1s)and Taiyuan(C3t)formations,respectively.The δ13 C1 values of the P1x gas are consistent with those of the P 1s gas and significantly different from those of the C3t gas.Compared with the P 1 s gas,the P 1 x gas mainly displays lower benzene/n-hexane,benzene/cyclohexane and toluene/n-heptane ratios,as well as significantly higher n-heptane/methylcyclohexane ratios.Geochemical characteristics of light hydrocarbons and carbon and hydrogen isotopic compositions of alkanes indicate that,the Upper Paleozoic natural gas from the Daniudi Gas Field is typical coal-derived gas.The P1s and C3t gases were in-situ self-generated and self-accumulated,whereas the P1x gas was mainly derived from the underlying P 1s source rocks and accumu-lated via vertical migration in free phase,with insignificant contributions of the C3 t source rocks.Due to the effect of migration and water solution of natural gas,the deviation exists in the identification of thermal maturity for tight gas from the Daniudi Gas Field using the light hydrocarbon indexes such as heptane and isoheptane values and benzene/n-hexane ratios.

外文关键词：

light hydrocarbon compoundsthermal maturitynatural gas origingas-source correlationmigra-tion phase stateDaniudi Gas FieldOrdos Basin

作者：

倪春华、吴小奇、王萍、王付斌、贾会冲、朱建辉、张毅、姜海健

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作者单位：

中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡 214126

中国石化油气成藏重点实验室,江苏无锡 214126

中国石化华北油气分公司油气勘探管理部,郑州 450006

中国石化华北油气分公司勘探开发研究院,郑州 450006

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关键词：

轻烃化合物成熟度天然气成因气源对比运移相态大牛地气田鄂尔多斯盆地

基金：

国家自然科学基金国家自然科学基金中国石化科技部攻关项目中国石化科技部攻关项目中国石化科技部攻关项目

项目编号：

42172149U2244209P23230P22132P21077-1

出版年：

2024

DOI：

10.11781/sysydz202402366

石油实验地质

中国石油化工股份有限公司石油勘探开发研究院中国地质学会石油地质专业委员会

石油实验地质

CSTPCD北大核心

影响因子：2.409

ISSN：1001-6112

年,卷(期)：2024.46(2)

参考文献量44