Abstract
Volcanic oil and gas reservoirs are generally buried deep, which leads to a high whole-well coring cost, and the degree of development and size of reservoirs are controlled by volcanic facies. Therefore, accurately identifying volcanic facies by logging curves not only provides the basis of volcanic reservoir prediction but also saves costs during exploration. The Songliao Basin is a ‘fault-depression superimposed’ composite basin with a typical binary filling structure. Abundant types of volcanic lithologies and facies are present in the Lishu fault depression. Volcanic activity is frequent during the sedimentary period of the Huoshiling Formation. Through systematic petrographic identification of the key exploratory well(SN165C) of the Lishu fault-depression, which is a whole-well core, it is found that the Huoshiling Formation in SN165C contains four facies and six subfacies, including the volcanic conduit facies(crypto explosive breccia subfacies), explosive facies(pyroclastic flow and thermal wave base subfacies), effusive facies(upper and lower subfacies), and volcanogenic sedimentary facies(pyroclastic sedimentary subfacies). Combining core, thin section, and logging data, the authors established identification markers and petrographic chart logging phases, and also interpreted the longitudinal variation in volcanic petro-graphic response characteristics to make the charts more applicable to this area's volcanic petrographic interpretation of the Huoshiling Formation. These charts can provide a basis for the further exploration and development of volcanic oil and gas in this area.
