Abstract: Lunnan buried hill reservoir is a super large carbonate reservoir, with the relative height 1000~1500m, the acreage 10000km2, and the buried depth 4100m. The main reservoir is the Ordovician carbonate karst weathering crust cracks-cave system. Above the hill, there is a giant thick Ordovician or Carboniferous mudstone onlapped on the slopes as a capping formation, but an area of more than 80km2 in the top is covered by thick Triassic waterbearing sandstone, so a top-window area comes into being. It is just because of the top window that a special type of reservoir is formed, i.e. the topopening buried hill reservoir. In this type of reservoir, oil and gas are mostly accumulated in the slopes surrounding the hill. The upper area near the top is water area or oil/water bearing area. The oil-water interface in the reservoir is tilting, and the oil-gas accumulation has unique hydrodynamic features.

Key words: Tarim Basin, Lunnan buried hill, top-opening buried hill reservoir, top window, hydrodynamic trap, dynamic accumulation