Abstract:

This paper summarizes the reservoiring patterns in Mahai Dahonggou salient in northern edge of Qaidam basin. Reservoiring pattern in the deeper part is of early primary accumulation with long period of hydrocarbon charging, which is characterized by multi stage (at least two stages) hydrocarbon migration and reservoiring. While Reservoiring pattern in the shallower part is of early expulsion and accumulation and late secondary reservoiring, which is characterized by late and once reserviring. Trap forming stages and reservoiring stages that are corresponding to the two major tectonic movements and two fault systems in the palaeo salient area are critical to the formation of these two different types of accumulations. Lunanshan piedmont structural zone, Mahai Huangnitan structural zone, Nanbaxian Donglingqiu anticlinal zone and the stratigraphic overlapping areas on the southwest and southeast limbs of Mahai structure are the major exploration targets in the future.

Key words: Mahai dahonggou salient, hydrocarbon accumulation, reservoiring pattern, exploration target, northern edge of Qaidam basin