塔中Ⅰ号坡折带顺西区块顺7井油气地球化学特征及来源

Geochemical characteristics and origin of hydrocarbons in the Well Shun-7 of western Shuntuoguole Block,Tarim Basin

马安来 金之钧 李婧婧 朱秀香

Ma Anlai Jin Zhijun Li Jingjing Zhu Xiuxiang

在塔中Ⅰ号坡折带顺西区块顺7井的中、下奥陶统鹰山组获得了凝析油与天然气。凝析油具有饱和烃含量高、芳烃含量低、非烃沥青质含量低的特点,饱芳比和非沥比分别为13.51和18.50。凝析油Pr/Ph比为1.16,庚烷值和异庚烷值分别为33%和3.8,为高成熟凝析油。在生物标志物组成上,由于成熟度较高,藿烷系列基本消失,三环萜烷以C三环萜烷为主峰。凝析油具有较重的碳同位素,全油碳同位素值为-29.6‰,与公认的寒武系生源的塔东2井原油具有相近的碳同位素值,因而凝析油可能来源于寒武系烃源岩。顺7井天然气为湿气,天然气甲烷碳同位素值仅为-51.7‰,与TZ45井奥陶系天然气甲烷碳同位素值相近;天然气组分同位素值分布呈现正碳同位素序列。该天然气的来源可能为上奥陶统烃源岩。

Condensate oil and natural gas were tested in the Yingshan Formation of the Lower-Mid Ordovician in well Shun-7 of western Shuntuoguole Block in Tazhong-Ⅰ faulted-slope-break zone,Tarim Basin.The condensate oil features in high content of saturate hydrocarbon and low content of aromatic hydrocarbon and non-hydrocarbon asphaltene.The ratio of saturate hydrocarbon to aromatic hydrocarbon and non-hydrocarbon to asphaltene are 13.51 and 18.50,respectively.The Pr/Ph value is about 1.16 and the heptane and isoheptane values are 33% and 3.8 respectively,indicating high maturity of the condensate oil.As the maturity is high,hopanes series basically disappear and tricyclic terpanes is dominated by C-tricyclic terpanes.The carbon isotope of the condensate oil from well Shun-7 is -29.6‰ and is similar to that of the Cambrian-sourced oil from well TD-2,indicating the condensate oil of well Shun-7 might originated from the Cambrian source rocks.The wet gas of the well Shun-7 has a methane carbon isotope value of -51.7‰,which is similar to that of the gas from the Ordovician in well TZ-45.The distribution of carbon isotopes of the gas components shows a normal carbon isotope sequence (i e,δC<δC<δC) indicating the gas may come from the Upper Ordovician source rocks.

10.11743/ogg20120602