Abstract: The weathering crust of Kalagang formation of Lower Permian in Malong sag, Santanghu basin is characterized by vertical weathered clay layer, highly weathered detritus, weakly weathered block layer and non-weathering rock interval. This paper analyzes the geologic conditions of the weathering crust formation and structural evolution feature, and then discusses the relationship between the weathering crust and the possible reservoir types. It is concluded that the favorable targets for petroleum exploration are in areas within denudation lines between the Tiaohu formation and Kalagang formation as well as area in east of denudation line of Kalagang formation.

Key words: Santanghu basin, Malang sag, weathering crust, structure, reservoir, target