Abstract: Both lower Cretaceous Yingcheng Formation and upper Jurassic Huoshiling Formation are partially composed of volcanic rocks in southern Songliao Basin. In Dongling area, most volcanic rocks of Yingcheng Formation are acidic and 73% of them belong to explosive facies while most volcanic rocks of Huoshiling Formation are basic. The volcanic rocks in Huoshiling Formation were divided into upper and lower series. 67% volcanic rocks of upper series are explosive facies and 59% volcanic rocks of lower series are explosive facies. Lenticular and mound shape, mid-strong or weak amplitude, low frequency, chaotic-bad continuity and diachronous phenomenon are the characteristics of seismic reflection for acidic rocks. The top boundary of acidic rocks shows a strong reflection. Eyeball and mound shape, weak reflection, worm like, low frequency, chaotic and bad continuity are characteristics of seismic reflection of basic rocks. Volcanic rocks were recognised by using inversion of simulated AC curve. The results showed that fault F₁ controlled the thickness of volcanic rocks and thicker in the west and thinner in the east. The thickest was around well SN109. Cones of volcanic edifices were recognised by using trend surface of structure and 3D slice methods. Two conedeveloped areas have been found in Huoshiling Formation. The cones distributed in 56 km² with structural amplitude of 547 m. Volcanic vent facies and extrusive facies were recognised with dip angle method based on the geophysical model of volcanic edifices. Explosive facies and effusive facies were recognised with waveform classification method. Integration of the dip angle method and waveform classification method recognises volcanic facies. The upper subfacies of effusive facies and volcanic vent facies well developed in the middle area of Huoshiling Formation. The cone-developed area is the first-rank target of volcanic prospect because of the thickest volcanic reservoirs and perfect permeability and porosity.

Key words: Southern Songliao Basin, Huoshiling Formation, Yingcheng Formation, volcanic reservoirs, inversion of simulated AC curve