天池铺构造石炭系油气地球化学特征与成因  

THE GEOCHEMICAL CHARACTERISTIC & ORIGIN OF CARBONIFEROUS IN TIANCHIPU STRUCTURE

作　　者：李延钧[1] 蒲洪果[1] 付晓文[1] 邓柳萍[1] 冯青平[2] 

机构地区：[1]西南石油大学资源与环境学院,四川成都610500 [2]中石油西南油气田分公司重庆气矿,重庆400021

出　　处：《西南石油大学学报（自然科学版）》2008年第3期50-54,共5页Journal of Southwest Petroleum University(Science & Technology Edition)

摘　　要：四川盆地东部天池铺构造天然气为干气,具有原油裂解气的特征,同时存在少部分后期高演化干酪根裂解气的贡献,原油为轻质油,油碳同位素偏重,是以汽油烃为主的凝析油,没有受到生物降解。通过对油气碳同位素、轻烃及油岩生物标志化合物等的综合研究,指出天池铺构造石炭系油气为腐泥型成因,成熟度高,均来自下伏志留系源岩。天然气与上二叠统煤系气具有明显的区别,凝析油碳同位素偏重主要与原油热蚀变(热裂解)和反凝析作用有关。成藏地球化学方法研究表明天池铺构造石炭系存在印支期古油藏,根据埋藏与热演化生烃史及古地温梯度计算可知石炭系已聚集的原油在白垩纪末期发生热蚀变(裂解)而转化为含油气藏。系统阐明了川东地区石炭系气藏属于古油藏裂解成因,并为川东地区寻找原油裂解气提供了科学依据。The natural gas of Tianchipu in the east Sichuan Basin is dry gas,with the characteristic of thermal cracking petroleum gas,meanwhile it consists of a little higher evolution kerogen cracking gas.It is a kind of higher carbon isotope,condensed oil,made up by light hydrocarbons almostly.This kind of oil hasn't been bio-degraded.By researching carbon isotope,light hydrocarbon,petroleum and source rocks biomarkers.It is pointed out that the gas and oil of carboniferous are sapropel-type with a higher maturity index,all are from lower Silurian source rocks.The study shows that natural gas is different from the coal gas from late Permian epoch.The formation of higher carbon isotope is petroleum thermal cracking and retrograde condensation.The geochemistry analysis of oil reservoir demonstrates that in the Carboniferous beds in Tianchipu,there exist the ancient reservoirs of Indo Chinese epoch.According to bury,thermal cracking history and geothermal gradient,it is known that the oil accumulated in Carboniferous changed to gas-oil reservoir at late Cretaceous period.This research systematically describes that gas reservoirs of Carboniferous in the eastern Sichuan basin belong to paleo-reservoir cracking origin,and provides a scientific basis for exploring oil cracked gas in the east Sichuan Basin.

关 键 词：热蚀变 油气轻烃 碳同位素 生物标志化合物 石炭系 

分 类 号：TE122[石油与天然气工程—油气勘探]