Different types of volcanic rocks are developed in Songliao Basin.Exploration activities revealed that oil/gas shows occur in all the volcanic rocks.In order to further understand the characteristics of favorable volcanic reservoirs,a comparative study for reservoir space,pore structure and physical property is conducted by using core,thin section and test data.The distribution of primary voids are extremely uneven in different types of volcanic reservoirs,that of secondary pores and fractures is better,and that of primary micropores and fractures is relatively even.Five throat types are identified,including coarse throat,medium-coarse throat,fine throat on the high side,fine throat and very fine throat.There are 6 types of porosity distribution,including high porosity with single peak,high porosity with double peak,medium porosity,medium-low porosity,lower porosity and low porosi-ty.Permeability distribution can be grouped into five types,namely high permeability,medium-high permeability,medium permeability,medium-low permeability and low permeability.Based on the four parameters mentioned above,it is believed that vesicular rhyolite,rhyotaxitic rhyolite,spherulitive rhyolite,ignimbrite,brecciated lava and breccia reservoir have good poroperm characteristics,while tuff,massive basalt,tuffaceous breccia and sedimentary tuff are poor in reservoir quality.
