The Mesozoic volcanic reservoirs in Songliao basin formed in the Late Jurassic to Early Cretaceous volcanic-sedimentary sequences. The vertical or lateral contacts between the deep lacustrine argillaceous rocks and volcanic rocks are the key factors of the formation of volcanic reservoirs during the volcanic-fault depression period—basin forming. Rock types of volcanic reservoirs include mainly lava and pyroclastic rock.The major volcanic reservoirs are mainly in the effusive facies

and the best reservoir belts are in the gas cavity belts on top and at base of the effusive facies. The reservoir spaces can be divided into primary pores

secondary pores and fissures. The volcanic reservoirs are mainly controlled by both NNE and nearly EW regional faults

most of them occur in active regional fault zones

basement uplifts or tectonic zones.