楚雄盆地含油气系统分析及勘探目标选择

Petroleum System and Exploration Targets in Chuxiong Basin

楚雄盆地是在扬子板块西南大陆边缘上发育起来的晚三叠世—早白垩世前陆盆地与晚白垩世—第三纪陆内湖盆叠置的构造—沉积残留盆地。含∈_1、D_2、T_3、J_(2+3)四套有效烃源岩系,其中 T_3烃源岩为陆坡—滨岸型泥质岩和煤系地层,厚200～1690m,全盆地均有分布,为主力烃源岩。盆地有 T_3s、J—K_1和 K_2—E 三套区域盖层。存在晚燕山期和喜马拉雅期两个含油气系统,现今可划分出三类有效保存单元,共有保存型、次生型、晚生型、水溶气和深盆气等五种油气成藏类型。盆地北部次坳区属 I_1+I_2类保存单元,是找气的最有利区带;东部冲断区是找油的有利区带。其中,帽台山南缘、盐丰凹陷东斜坡、永仁凹陷西斜坡及云龙区带是油气勘探的首选区带,赵家店、昙华、双坝构造及乌龙口圈闭是钻探的有利目标。

Chuxiong Basin is a structural-depositional relict basin of Late Cretaceous-Tertiary intracontinental lake basin superimposed on Late Triassic-Early Cretaceous foreland basin which was developed on southwest margin of Yangzi plate.There are four sets of source rock,∈_1,D_2,T_3,J_(2+3),among them T_3 is the main one.It is a continental slope-shoreside argillaceous rock and coal measure strata,200～1690m thick,and distrituted in the whole basin.There are three sets,T_3s,J-K_1 and K_2-E,of regional caprock,and two petroleum systems of Late Yanshan and Himalayan stage in the basin.Four types of oil-gas preservation units and five types of pool-forming of preserved,secondary,Later generation,water-solube gas and deep basin gas may be classified at present.Type Ⅰ_1 + Ⅰ_2 preservation units in the secondary depression of northern part of the basin are most favorable for gas exploration,the eastern thrust zone is favorable for oil exploration.