松辽盆地主要断陷大中型油气田形成分布特征

FORMATION AND DISTRIBUTION FEATURES OF LARGE-MEDIUM OIL-AND-GAS FIELDS IN MAIN FAULT DEPRESSIONS IN THE SONGLIAO BASIN

在松辽盆地深部发育的30多个中生界断陷中,已发现的大中型油气田主要分布于贯穿盆地中央区域的北北东向孙吴—双辽岩石圈断裂两侧的徐家围子、十屋、长岭等3个富油气深断陷之中。这些深断陷的成油气地质条件和大中型油气田分布规律研究表明,大中型油气田分布在箕状深断陷生烃中心周缘发育的中央断垒带、缓坡坡折带、缓坡坡垒带、陡坡坡折带上的一批近东西向继承性鼻状隆起构造与地层超覆尖灭、岩性复合圈闭之中,其中,2个深断陷之间的中央隆起带往往是大型油气田的分布区域。为进一步发现大中型油气田,下一步应该围绕富油气深断陷的上述有利区带展开深度勘探。

More than 30 Mesozoic fault depressions develop in the center of the Songliao Basin. The discovered large-medium oil-and-gas fields mainly locate in the petroleum-rich deep fault depressions named Xujiaweizi, Shiwu and Changling on the two sides of the NNE oriented Sunwu-Shuangliao lithospheric fracture in the center of the basin. Study of the petroleum generating geologic condition of deep fault depressions and the distribution characteristics of large-medium oil-and-gas fields shows that, large-medium oil-and-gas fields mainly locate in the EW oriented inherited nose-like structures in the central fault horst zone, the gentle slope break zone, the gentle slope horst zone and the steep slope break zone around hydrocarbon generating center of half-graben deep faults and the lithospheric overlapping pinch and lithologic traps. The central uprising belts between two deep fault depressions are usually where large oil-and-gas fields can be found. The future exploration should be focused on the above-mentioned regions in deep fault depressions.