开鲁盆地钱家店凹陷姚家组砂岩中烃类地球化学特征及来源探讨

GEOCHEMICAL CHARACTERISTICS AND ORIGIN OF INCLUSIONS AND ADSORBED HYDROCARBONS IN YAOJIA FORMATION SANDSTONES IN QIANJIADIAN AREA, THE KAILU BASIN

李宏涛 吴世祥 蔡春芳 罗晓容 宝日玛

Li Hongtao Wu Shixiang Cai Chunfang Luo Xiaorong Bao Rima

中国石油化工股份有限公司, 石油勘探开发研究院, 北京, 100083 2. 中国科学院, 地质与地球物理研究所, 北京, 100029 3. 中国石油大学, 北京, 102249

Exploration & Production Research Institute, SINOPEC, Beijing 100083, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 3. China University of Petroleum, Beijing 102249, China

对开鲁盆地钱家店地区下白垩统姚家组砂岩中吸附烃和包裹体烃类进行色谱—质谱测试,分析了它们的地球化学特征,并讨论其可能的来源。吸附烃和包裹体烃生物标志物成熟度参数,C29ααα甾烷20S/(S+R)、C31αβ藿烷22S/(S+R)比值基本达到平衡值,显示含矿砂岩中的烃类已接近成熟—成熟热演化阶段;物质来源及沉积环境参数,ααα20R甾烷百分含量C27>C28 29,C 25/C 26三环萜烷、规则甾烷/17αC 29-33藿烷比值显示相对低值,结合伽马蜡烷指数、C 35升藿烷指数等参数,综合反映了其来源应为弱氧化—还原环境下的腐殖—腐泥型湖相有机质。这些特征与该凹陷侏罗系九佛堂组烃源岩地球化学特征相似,因而,油源可能来自九佛堂组烃源岩。

Inclusion hydrocarbons and adsorbed hydrocarbons were observed under microscope and UV fluorescence in Lower Cretaceous Yaojia Formation sandstones in Qianjiadian area,the Kailu Basin.Subsequently,these sandstone samples were washed,crushed,extracted for hydrocarbons and analyzed by GC and GC-MS.The results showed that ratios of C29 ααα sterane 20S/(20S+20R) and C31 αβ hopane 22S/(22S+22R) of the hydrocarbons were closed to respective equilibrium values,suggesting that the hydrocarbons were marginally mature to mature.Among C27,C28 and C29 ααα20R steranes,C27>C28 29.Ratios of C 25/C 26 tricyclic terpane and regular steranes/17αC 29-33 hopanes were relatively low.The values together with those of gammacerane index and homohopane index consistently indicated that the inclusion oils and adsorbed hydrocarbons were derived from humic-sapropel type organic matter under poor reducing freshwater to semi-saline environment.The features were similar to those of organic matter extracted from the Upper Jurassic Jiufotang Formation source rocks in the Kailu Basin.Thus,it could be concluded that the inclusion oils were mainly derived from the Upper Jurassic Jiufotang Formation source rocks of lacustrine facies.

国家重点基础研究发展计划(973计划)项目(2003CB214605)

https://doi.org/10.11781/sysydz200804375