Abstract:

The types of sandstone from Nantun and Tongbomiao Formation of Wuerxun depression in Hailaer basin are mainly debris-feldspar sandstone, sightly feldspar sandstone and feldspar-debris sandstone. The diageneses include compaction, cementation, metasomatism and dissolution, etc. With depth increasing, the porosity and permeability decrease. There are four relatively high porosity arears in about 1 500 m,1 850-2 050 m,2 300 m and 2 600-2 800 m. The reasons of relatively high porosity areas appearance are the preservation of primary porosity and the development of secondary porosity.The weakness of compaction and cementation, existence of clay coating and microcrystalline quartz are favor to the preservation of primary porosity；in the processing of thermal evolution of organic content and the conversion of clays, secondary porosity forming occurs.

Key words: Hailaer basin, sandstone, relatively high porosity areas, preservation of primary porosity, secondary porosity forming