塔里木盆地塔中4石炭系油藏成藏过程再认识

Reassessment of the Carboniferous oil pooling in Tz-4 field,the Tarim Baisn

杨楚鹏 张宝民 王飞宇 卢玉红 肖七林 张海祖 廖泽文 耿安松

Yang Chupeng Zhang Baomin Wang Feiyu Lu Yuhong Xiao Qilin Zhang Haizu Liao Zewen Geng Ansong

在塔里木盆地下古生界含油气系统中,塔中4石炭系油藏成藏过程具有代表性.对该油藏原油的分子以及碳同位素地球化学特征进行了系统解剖,结合区域地质演化特征和烃类成藏过程中储集层沥青、包裹体的记录,对其成藏过程重新进行了评价.研究揭示塔中地区存在两类烃源灶的分布,分别为中、上奥陶统烃源灶和中、下寒武统烃源灶,它们在不同地质历史时期的复合供烃造就了塔中4石炭系油藏;其中C油组属于原生性一次充注成藏,油源单一,后期几乎没有遭受任何地球化学作用的改造;C属于典型多源、多期充注、后期改造型油气藏,经历了较多的地球化学改造作用;C油藏与C油藏关系密切,部分油气为C油藏调整、改造的产物.

The oil pooling process in the Carboniferous Tz-4 field is quite typical in the Lower Paleozoic petro-leum system,Tarim basin.The molecule and carbon isotope geochemical behavior of oil in the field was analyzed systematically and the pooling process was reassessed based on regional sedimentology and tectonics as well as geochemical data of reservoir bitumen and fluid inclusions.The results indicate that two kinds of source kitchens(i.e.the Middle-Upper Ordovician and the Middle-Lower Cambrian) with different thermal evolution history in the central Tarim basin might have contributed to the formation of the Carboniferous Tz-4 oil pool.The C reservoir is thought to be formed by one hydrocarbon charging from a single oil source and suffered almost no geochemical alteration,whereas the C reservoir is characterized by diversified hydrocarbon sources,multiphase charging,and late modification.The results also suggest that the C reservoir has a close relationship with C reservoir,and is partly the product of C reservoir adjustment and modification.

10.11743/ogg20080205