Continuous tight sand gas is a significant unconventional resource for natural gas. To understand the progress of geological research on this kind of gas reservoir

this paper summarized the criteria for identification of tight sand reservoirs

their classification

geological characteristics

elements of hydrocarbon accumulation

and trapping mechanisms. The current criteria for identivation of continuous tight sand gas reservoirs does not take accumulation conditions into consideration. The real critical conditions of tight sand gas change along with hydrocarbon accumulation conditions. The key elements of hydrocarbon accumulation in tight gas reservoir involve hydrocarbon source rock

tight sandstone close to source rock and stable tectonic environment. It should be noted that the nature of tight sandstone is nano-micro scale pore throat and the percentage of pore throats is about the same as that of pores

and that abnormal pressure is not an essential difference between tight sand gas reservoir and conventional gas reservoir. Several key issues concerning continuous tight sand gas accumulation are presented. The first is study on dynamic trapping mechanism for tight sand gas reservoir

i. e. the force balance between driving force（ gas pressure） and resistance（ capillary force

viscous force and formation water pressure） at the interface of gas water inversion. The quantitative description and simulation of evolution of these forces are particularly important. The second is the research on the mechanism and process of adjustment of tight sand gas reservoir as well as restoration of the original tight sand gas reservoir. The restoration of the original reservoir can be realized by means of force balance relation at the interface of gas water inversion. All of the late adjustment and modification were realized through changing the critical conditions of gas water inversion. The third is study of the control of sandbodies with relatively high porosity and permeability on gas accumulation in tight sandstone. The existence of these sandbodies changes the accumulation conditions and complicates the accumulation process.