Abstract: In response to the problem that the unclear lower limit of the physical properties of the effective reservoir in He 7 - He 8 Members of Linxing Area, based on the physical properties data, logging interpretation results, gas test data, sedimentary phases, casting thin section and other information, the analysis of the main controlling factors for the development of effective reservoir was carried out by combining the cumulative frequency method, the gas recovery index method, and the rendezvous chart analysis method. The study shows that the lower limits of porosity for He 7 - He 8 Members are 6.0% and 5.5%, respectively, and the lower limits of permeability are 0.05 mD and 0.04 mD, respectively. Effective reservoirs are controlled by the combination of sedimentation, diagenesis and tectonics, and the sedimentation controls the spatial spreading and development scale of reservoirs, which is the main factor affecting the physical properties of reservoirs; the diagenesis has a more complicated influence on the physical properties of reservoirs, among which, the compaction intensifies the degree of densification of reservoirs, secondary pores produced by dissolution and erosion are conducive to the formation of effective reservoirs, and the cementation has two sides to the development of effective reservoirs; late tectonics facilitates the formation of microcracks of tectonic origin and promotes the mineral dissolution, which is of positive significance to the improvement of local reservoir connectivity. The above understanding is instructive for effective reservoir prediction as well as oil and gas exploration in coal seams in the Linxing Area.

Key words: effective reservoir, lower limit of physical properties, main controlling factors, lower Shihezi Formation, central Linxing Area