PROSPECT OF PETROLEUM FRONTIER IN THE MID-SMALL SIZED MESOZOIC BASINS, NORTH CHINA：A VIEW OF PETROLEUM ACUMULATION CONDITION

The suitable paleoclimatic and paleogeographic condition in the Jurassic-Cretaceous period provided a favourable depositional environment for formation of hydrocarbon-bearing basins in the north of QinglinQilian-Kunlun orogenic belt.The Yanshanian tectonic activity was strong in the end of the Jurassic and the end of the Cretaceous,which resulted in inversion of basins and formation of two petroleum systems of the Early-Middle Jurassic and the Late Jurassic-Early Cretaceous.Accumulation was formed in late Yanshanian and Himalayan movement.It was pointed out that hydrocarbon was sourced from the Lower and Middle Jurassic coal-bearing sequence via vertical or lateral migration in the mid-small Mesozoic foreland basin in northwestern China,and hydrocarbon was sourced from the Upper Jurassic-Lower Cretaceous coal-bearing sequence in faulted basins in northeastern China.The related accumulations formed in those areas are the potential targets for exploration.