塔中地区志留系砂岩中孔隙游离烃和包裹体烃对比研究及油源分析

Comparative study of free hydrocarbons in pores with inclusion hydrocarbons and oil-source rock correlation for Silurian sandstone in Tazhong area

朱东亚 金之钧 胡文瑄 张学丰 姚素平

Zhu Dongya Jin Zhijun Hu Wenxuan Zhang Xuefeng Yao Suping

对塔里木盆地塔中地区6个志留系沥青砂岩样品中的孔隙游离烃和包裹体烃,做了分离并分别进行了色-质分析。色-质分析表明孔隙游离烃和包裹体烃具有显著不同的特征:前者表现为前峰型轻质烃特点,主峰碳较小(为C或C),无奇碳优势,多伴有生物降解现象;而后者多表现出双峰分布特征,主峰碳数较大(为C或C),有一定奇碳优势。在生物标志物上,孔隙游离烃三环萜烷和孕甾烷含量都较高,C,C和C甾烷呈不对称"V"字型分布;而包裹体烃的三环萜烷和孕甾烷含量都较低,C,C和C甾烷呈斜线上升型分布。油源对比表明,沥青砂岩包裹体中捕获的烃与中-下寒武统烃源岩有关,而孔隙游离烃则与中-上奥陶统烃源岩有关。

Pore free hydrocarbons and inclusion hydrocarbons in 6 Silurian bituminous sandstone samples from the Tazhong area of Tarim basin are separated and analyzed with GC and GC-MS.The analysis results show that pore free hydrocarbons and inclusion hydrocarbons have different characteristics.The pore free hydrocarbons are represented by light hydrocarbons of pre-peak distribution and peak carbon number at C or C,without odd carbon number predominance,which are usually associatee with significant biodegradation.The inclusion hydrocarbons are represented by heavy hydrocarbons of bimodal distribution and peak carbon number at C or C,with odd carbon number predominance.In respect of biomarker,the pore free hydrocarbons have a relatively high concentration of tricyclic terpanes and pregnane,with the C,C and C steranes of asymmetrical "V" distribution;whereas the inclusion hydrocarbons have a relatively low concentrations of tricyclic terpanes and pregnane,with the C,C and C steranes of oblique-ascending distribution.Oil-source correlation indicates that the hydrocarbons entrapped in the inclusions of bituminous sandstone might be sourced from the Middle-Lower Cambrian source rocks,while the pore free hydrocarbons might be generated by the Middle-Upper Ordovician source rocks.

10.11743/ogg20070104