伊犁盆地伊宁凹陷二叠系与三叠系主要烃源岩特征对比研究

CHARACTERISTICS OF PERMIAN AND TRIASSIC SOURCE ROCKS IN YINING SAG OF YILI BASIN

重点对伊利盆地伊宁凹陷二叠系与三叠系主要烃源岩的有机质丰度、有机质类型、有机质成熟度特征进行分析与对比。盆地二叠系主力烃源岩为铁木里克组,三叠系主力烃源岩为小泉沟群。该盆地二叠系铁木里克组烃源岩机质丰度较好,已处于成熟—高熟阶段,有利于油气的形成,是好的生油岩;盆地三叠系小泉沟群烃源岩表现为有机质丰度高,成熟度较低,生油能力较二叠系差,属于中等生油岩。二叠系铁木里克组烃源岩干酪根碳同位素δ13C介于-23.55‰~20.85‰,指示有机质母质类型为Ⅱ—Ⅲ型有机质。三叠系小泉沟群烃源岩δ13C介于-26.51‰^-20.45‰范围内,代表Ⅱ型有机质。通过镜质体反射率Ro、最高热解峰温、饱和烃轻重比、OEP值研究表明伊宁凹陷二叠系铁木里克组烃源岩有机质成熟度高,三叠系小泉沟群烃源岩成熟度相对低。总体评价认为二叠系铁木里克组烃源岩是伊犁盆地伊宁凹陷的主力烃源岩,生烃能力强,是盆地油气勘探的重点层位。

Focus on the organic matter abundance, organic matter type, organic matter maturity characteristics of Permian and Triassic source rock were analyzed and compared from Yining Sag of Yili Basin. The source rocks organic matter abundance of good, in advanced high-mature stage, is conducive to the formation of oil and gas, is a good source rocks; Xiaoquangou Th source rock showed high organic matter abundance, low organic matter maturity, lower oil generation capacity than the Triassic check belonging Average-oil rocks. Permian source rock kerogen carbon isotope δ13C between-23.55‰～-20.85‰, indicating Ⅱ-Ⅲ organic matter type. Tri assic source rocks within the range of δ13C-26.51‰～-20.45‰ range, representing the type Ⅱ organic matter. By Ro, the highest pyrolysis peak temperature, saturated hydrocarbons weight ratio, OEP value studies show organic matter maturity of Permian source rocks is more upper than Triassic source rock maturity. Overall assessment is that the Permian source rocks is main source rocks, is high hydrocarbon generation ability, is the focus of Basin oil and gas exploration horizon in Yining Sag of Yili Basin.