吉尔吉斯阿莱依盆地含油气远景分析

Hydrocarbon perspective of the Alay Basin, Kyrgyzstan

阿莱依盆地是特提斯北缘盆地群中的一个,晚三叠世—古近纪与相邻的塔吉克盆地、塔里木盆地西南坳陷基本连通,中新世以后才成为分隔的周缘前陆盆地。该盆地现今面积约5500km^2,推测沉积岩最厚达8km,地层北薄南厚,推测南侧出露的地层为外来的推覆体,北侧出露的是原地体,其形成与帕米尔北地块由南向北俯冲有关。根据与相邻盆地的类比,结合该区十分有限的资料推测,阿莱依盆地可能存在2套成熟烃源岩(古近系暗色泥岩,白垩系灰岩、泥灰岩和泥岩),可能发育的合煤侏罗系也是可能烃源岩;至少存在2套成藏组合(白垩系和古近系),新近系也可能形成次生油气藏;油气藏类型主要是被断层复杂化的背斜油气藏,以带气顶的油藏或凝析气藏为主。1991年在盆地内阿莱依1号构造钻探的阿莱依-1井未发现油层,认为该井钻在油水过渡带,阿莱依1号构造可能是一个背斜油藏。

Along with Tajik Basin and the Southwest Southwest Depression of Tarim Basin, Alay Basin was one of the remnant basins on the north rim of the Tethys during the Late Triassic to Paleogene, it became a peripheral foreland basin in Miocene. It is estimated that the maximum thickness of sediments is approximately 8000 m in the south. The sediments become significantly thiner to the north. Based on correlation with other nearby basins, it is predicted that the Cretaceous limestone and the Paleogene black shale/mustone are present in the subsurface of the basin. The coal-bearing Jurassic is likely the source rock. The reservoirs should be developed in faulted anticlines of Cretaceous and Paleogene rocks, and possibly Neogene sediments. However, no reservoir was found in Well Alay-1 which was drilled in 1991. It is probably due to penetration of the oil-water transition zone. The Alay Basin possesses considerable hydrocarbon potential.