四川盆地陆相碎屑岩油气圈闭分布特征及成因机制

Distribution Characteristic and Genetic Mechanism of Hydrocarbon Traps of the Terrestrial Clastic Rock in Sichuan Basin

通过对四川盆地典型陆相碎屑岩油气田的统计分析,认为四川盆地陆相碎屑岩气田圈闭类型主要有构造圈闭、岩性圈闭和构造-岩性复合型圈闭,构造圈闭主要类型为背冲断块圈闭,岩性圈闭主要为泥灰岩中的多层砂岩透镜体相互叠置。四川盆地陆相碎屑岩层系油气田的圈闭分布自西向东可以划分出3个构造带,即背冲断块构造圈闭带、构造-岩性复合型圈闭带、岩性圈闭带,形成这种分布模式的主要原因为四川盆地构造特征的分带性,从龙门山冲断带的马角坝-通济场-双石断裂带到川东地区,可以划分为4带,分别为冲断带、凹陷带、隆起带、高陡褶皱带。此外圈闭分布在南北向上具有明显的分段性,这种分段模式同样是由构造变形的差异性以及构造演化的差异性所决定。

Based on the statistical analysis of terrestrial clastic hydrocarbon fields in Sichuan basin, this study concludes that the traps in Sichuan basin can be classified into three types： structural trap, lithologic trap, and structural-lithologic compound trap. The type of structural trap is back thrusting block one. Lithologic trap is defined chiefly by superimposition of multi-layer sandstone lens. Traps of the terrestrial clastic hydrocarbon fields in Sichuan basin can be divided from west to east into three structural belts： pop-up trap belt, structural-lithologic compound trap belt, and lithologic trap belt. The pattern of such kind attributed to zoning of the structural features of Sichuan basin. From Majiaoba-Tongjichang-Shuangshi faulting zone in the Longmengshan thrusting zone to northeastern Sichuan, four belts can be recognized： thrust belt, depression belt, uplift belt and steep folding belt. Besides, trap distribution manifests distinct segmentation from south to north, the mode of which, in the same way, depends on deformation and evolvement differences of structures.