New oil and gas exploration field:volcanic hydrocarbon reservoirs Enlightenment from the discovery of the large gas field in Songliao basin

Based on the new insight into the volcanic sequence coupled with associated theory and technique innovation,large volcanic gas fields were successfully found in the Songliao basin NE China.Volcanic rocks have thus been changed from the forbidden zone to the target in oil and gas exploration for the first time there.This has promoted the volcanic exploration of China and brought rapid growth of petroleum reserves in recent years.Compared with sedimentary rocks,volcanics in deep of the basin have three major advantages including large volume,little change of reservoir space with depth of burial,better porosity and permeability.Various volcanic rocks can become effective reservoirs.Volcanic successions developed mainly in early stage of the basin evolution and interbedded with noncompensated sedimentary sequence of rapid subsidence, which could form different kind of combination of petroleum system.In addition,volcanic reservoirs have more chance to receive gases from multi-sources.Therefore,deep basin volcanics will inevitably become favorable exploration targets for oil and gas.Although there are geologically the potential for forming the two trillion square sized volcanic gas regions in the eastern and western of China,a lot of work left to be done.Volcanic oil and gas exploration is just at the preliminary step globally.Their resource potential has been greatly underestimated up to now.We therefore believe that volcanic reservoirs will certainly become important field of oil and gas exploration in the near future.