College of Earth Sciences��Jilin University��Changchun 130061��China

The pore structural characteristics of Devonian Donghetang Formation reservoir in Bachu--Maigaiti area of Tarim Basin has been studied combined with mercury analysis testing and SEM observation of drill cores�� The results show that the pores of reservoir sands are mainly primary pores ( residual intergranular pores) in type�� followed by a few secondary pores ( dissolution pores) �� The reservoirs are characterized by very low porosity and ultra- low permeability��belonging to ultra-low porosity and ultra-low permeability reservoirs with thin pore throat and poor porous condition�� The pore structure can be divided into three types��in which the type �� is the main one ( 75%) �� The pore structural characteristics are influenced by the diagenesis and sedimentation��in which diagenesis is the main influencing factor��