Abstract: According to eruptive scale illustrated by drilling lithology, facies characteristics and seismic data, early Cretaceous volcanic edifices of Yingcheng Formation in Xujiaweizi faulted depression, Songliao Basin were classified into pyroclastic volcanic edifice, lava volcanic edifice and compound volcanic edifice. The facies composition of pyroclastic volcanic edifice was listed as fellows: 9.3% for volcanic vent facies, 55.3% for explosive facies, 29.2% for effusive facies, 1.4% for extrusive facies and 4.8% for volcanic sedimentary facies. The pyroclastic volcanic edifices is 0.5-1.5 km wide and 50-220 m thick. The facies composition of lava volcanic edifice was 8.1% for volcanic vent facies, 23.4% for explosive facies, 62.6% for effusive facies, 5.1% for extrusive facies, and 0.8% for volcanic sedimentary facies. The lava volcanic edifices is 1-2 km wide and 200-300 m thick. The facies composition of compound volcanic edifice was 4.9% for volcanic vent facies, 34.4% for explosive facies, 56.8% for effusive facies, 2.6% for extrusive facies and 1.3% for volcanic sedimentary facies. The compound volcanic edifices is 2-4 km wide and 300-450 m thick. The scale of reservoir flow unit is controlled by subfacies of volcanic edifices. So the scale of reservoir flowing unit is various for each volcanic edifice, pyroclastic volcanic edifice is 0.3-1.5 km in width and less than 60 m in thickness, lava volcanic edifice is 1-2 km in width and less than 80 m in thickness, compound volcanic edifice is 1.5-3.0 km in width and less than 100 m in thickness. So the distance of wells and hydraulic fracturing plan are different in each kind volcanic edifice during the development.

Key words: Songliao Basin, Yingcheng Formation, volcanic edifices type, facies model, reservoir flow unit