鄂尔多斯盆地姬塬地区延长组下组合油源特征综合研究

Comprehensive Research of Oil-Source Rock Correlation of Lower Yanchang Formation in Jiyuan Field,Ordos Basin

在充分总结姬塬地区延长组下组合大量原油及烃源岩生物标志化合物资料的基础上,结合研究薄弱带的铁边城区块的原油样品族组分组成、饱和烃色质及烃源岩样品总有机碳、热解、族组分组成及饱和烃色质测试结果,系统分析了研究区目的层段的油源特征,并明确了原油与烃源岩在空间上的匹配特征。结果表明,C 30重排藿烷含量差异能够有效区分长7、长9烃源岩及生成烃类。长7油页岩为主力烃源岩,长7灰黑色泥岩次之。在姬塬地区东南部的铁边城区块存在长9烃源岩分布,且对长9油层组有一定程度的生烃贡献。空间上,姬塬地区延长组下组合的油源特征具有明显的分区性,大致以古峰庄东—红井子—姬塬西—樊学西南为分界,界限东北部区域的Ⅰ类原油为西南部长7油页岩长距离侧向运聚结果,东南端的ⅠⅡ类过渡型原油为长7油页岩与长9暗色泥岩混合贡献产物;界限西南部区域的ⅡⅢ类原油来自长7黑色泥岩。

On the basis of biomarker data for crude oil and source rock from Lower Yanchang Formation in Jiyuan area of Ordos basin,this paper systematically analyzed oil source characteristics and clarified the spatial matching characteristics of crude oil and source rock with reference to group component and saturated hydrocarbon chromatin of crude oil,and total organic carbon,pyrolysis,group component,saturated hydrocarbon chromatin of source rock from Tiebiancheng Field.The results showed that C30 diahopane can be used to effectively distinguish the source rock and related hydrocarbon of Chang 7 from those of Chang 9.In Chang 7,oil shale is the main source rock,followed by grayish black mudstone.In Chang 9 source rock develops in Tiebiancheng Field of southeastern Jiyuan Area,which also contributes some hydrocarbon generation.In space,the oil-source rock of Lower Yanchang Formation in Jiyuan area has an obvious boundary of eastern Gufengzhuang-Hongjingzi-western Jiyuan-southwestern Fanxue.In the northeastern region of the boundary,crude oil of TypeⅠderived from the long-distance lateral migration and accumulation of Chang 7 oil shale;in the southeastern end of the boundary,transitional crude oil of Type Ⅰ-Ⅱ is the mixture of Chang 7 oil shale and Chang 9 dark mudstone;in the southwestern region,crude oil of Type Ⅱ-Ⅲ is from Chang 7 black mudstone.