准噶尔盆地油气成藏期次确定与成藏组合划分

Timing of petroleum accumulation and the division of reservoir-forming assemblages,Junggar Basin,NW China

叠合盆地油气成藏研究不仅需要确定成藏期次,而且还要结合垂向封隔层的分布,将不同成藏期的油气藏从垂向上划分为不同的成藏组合,以期更准确地反映油气成藏过程和描述油气空间分布。以准噶尔盆地玛湖—盆1井西复合含油气系统为例,基于储集层自生伊利石K-Ar同位素测年、包裹体光性特征与均一温度分析、埋藏-热演化史分析,确定该油气系统共有4个主要的成藏期(P2—3、T3J、2—K1和N)。在此基础上,结合垂向封隔层(T3b、J1s1、K1tg泥岩)的分布,划分出C—T3、T3—J1J、2—K1和K—N等4个成藏组合,不同的成藏组合在不同区带具有不同的勘探意义。

Timing of petroleum accumulations and the distribution of vertical basin-scale sealing beds are important in the study of superimposed basins.They can be used to divide petroleum accumulations of different times into different petroleum-forming assemblages vertically so as to reconstruct the petroleum accumulation process and distribution more accurately.The Mahu-West Well Pen 1 combination petroleum system in the Junggar Basin is taken as a case study.By isotopic K-Ar dating of authigenic illites,optical feature of organic inclusions,and fluid inclusion homogenization temperature,combined with burial and thermal history analysis,the timing of petroleum accumulations is defined,i.e.P2-3,T3,J2-K1 and N.According to the vertical sealing mudstones of T3b,J1s1,and K1tg,four petroleum-forming assemblages are divided including C-T3,T3-J1,J2-K1,and K-N.