Northeast Oil & Gas Branch of SINOPEC, Changchun 130062, China 

 Based on the core and thin section data, combined with the seismic and physical properties tests, the characteristics and development regularity of the volcanic rock reservoirs in the Huoshiling Formation of Chagan? hua subsag, Changling fault depression have been studied. The results show that the volcanic rocks were erupted at three stages with four types of lithology. Stage 1 is a subaerial eruption, mainly dominated by effusive facies and ex? plosive facies. Stage 2 is developed in a transitional eruption environment with a large number of volcanic?sedimen? tary facies. Stage 3 is a subaqueous environment eruption, which is dominated by subaqueous explosive facies. Volcanic rock reservoirs are mainly developed in tuffaceous sandstones of the volcanic sedimentary facies (stage 2) and medium?coarse grained tuffs of the subaqueous explosive facies ( stage 3). The reservoir space of middle? coarse grained tuff reservoir is dominated by a large number of devitrified pores, while the reservoir space of tuf? faceous sandstone reservoir is dominated by dissolution pores. Both types of reservoirs are microporous reservoirs, with a medium pore value of 3. 8% and a median permeability value of 0. 03 × 10 - 3 μm 2 . The tuffaceous sandstone reservoirs of stage 2 are widely distributed and stratified. The middle?coarse grained tuff reservoirs of stage 3 are de? veloped lenticular in space and developed near the volcanic eruption center.