Tight gas reservoir sandstones are generally defined as gas-bearing and-yielding sandstones with porosity of less than 10% and permeability to gas less than 0.1md.Tight gas reservoir sandstones are characterized by high capillary entry pressures

high irreducible water saturations and predominance of secondary pores.This paper suggests that tight reservoir sandstones be classified into four types in terms of the origin:1)tight sand formed by sedimentation of large amount of authigenic clay minerals;2)tight sand resulted from crystallization and precipitation of cements altering primary pores;3)tight sand caused by compaction of large amount of ductile clasts;4)tight sand formed by filling of intergranular pores by detrital clay matrix.To explain the origin of se-condary pores in these sandstones

researchers have developed many theories.However

none of the theories are capable of clearing all the doubts due to the complexity of this kind of reservoirs.As a result

the issue is still in debate.Despite their complex burial history of tight reservoir sandstones and diagenesis being determinant in tightening of sandstones

original depositional environment is still a basic factor controlling the formation of tight sandstone reservoir.Deeper understanding of their depositional environment and the diagenetic history is critical to the prediction and evaluation of tight reservoir sandstones.