鄂尔多斯盆地中部气田奥陶系风化壳混源气成藏分析  

Formation of source-mixed gas reservoir in Ordovician weathering crust in the central gas-field of Ordos Basin

作　　者：程付启[1] 金强[1] 刘文汇[2] 陈孟晋[3] 

机构地区：[1]中国石油大学地球资源与信息学院,山东东营257061 [2]中国石化石油勘探开发研究院,北京100083 [3]中国石油勘探开发研究院,北京100083

出　　处：《石油学报》2007年第1期38-42,共5页Acta Petrolei Sinica

基　　金：国家重点基础研究发展规划(973)项目(2001CB209102)资助

摘　　要：鄂尔多斯盆地中部气田奥陶系风化壳具有同时捕集上古生界煤成气和下古生界油型气的地质条件，为煤成气和油型气混源成藏。为了确定中部气田混源气的混合比例，并探讨其成藏特征，将上古生界煤成气和下古生界油型气作为2个端元，利用甲烷、乙烷碳同位素组成和体积分数与母质成熟度的经验关系式，建立了两源混合比例动态判定模型。由该模型可知，不同井中两端元气的混合比例相差很大，煤成气和油型气比率分别为22％～84％和16％～78％。这一结果表明，奥陶系风化壳气藏是由多个相互分隔的小气藏组成的；上古生界煤成气进入风化壳的方式，早期以整体顶渗为主，后期转为从侵蚀沟侧向侵入。The Ordovician weathering crust of the central gas-field in Ordos Basin could capture the Upper Paleozoic coal-typed gas and the Lower Paleozoic oil-typed gas and was proved as a source-mixed gas reservoir. The volume content and stable carbon isotopic compositions of methane and ethane have the quantitative relationship with the maturities of their source rocks. By using these rela- tionships, a model for calculating the ratio of source-mixed gas was established. According to the model, the percentages of the Upper Paleozoic coal-typed gas and the Lower Paleozoic oil-typed gas are in the range of 22% to 84% and 16% to 78%, respectively. The large ranges of ratio between the two kinds of gases suggest that the gigantic weathering crust reservoir was made up of several isolated small gas pools. It is also shown that the main way for coal-typed gas entering the crust reservoir was eroded channel.

关 键 词：鄂尔多斯盆地 中部气田 风化壳气藏 混源气 成藏过程 

分 类 号：TE112.1[石油与天然气工程—油气勘探]