| Large scales of volcanic reservoir are developed in the middle section of the eastern depression of Liaohe Rift. Due to the unique and complex nature of volcanic reservoir, its quantitative evaluation and distribution prediction has become a difficult problem for the exploration and development of volcanic reservoir that seriously hinders the effectiveness of the exploration and development of reservoirs of the same kind. In view of the main geological issues that constrain the oilfield production, this paper conducted a comprehensive evaluation towards volcanic reservoir based upon core data, experimental analysis and with the help of modern electrical logging and it has been verified via production test. The major achievement includes:1. Through observation, description, slice identification of cores and chemical analysis of whole rock, it is determined that the central volcanic rocks of the Eastern Depression are classified as four major types, i.e. basalt, trachyte, tuff and cataclasite of sedimentary volcanic rocks, in which trachyte is of basic series and potassium rock type. Based on genetic analysis, the volcanic rocks in this area are divided into four lithofacies: explosive , overflow, intrusive and volcanic sedimentation facies, in which the explosive and overflow are favorable facies for reservoir development.2. Reservoir study shows there have been primary and secondary reserving pores developed in the volcanic rock reservoirs of this area, the secondary pore being dominant. The secondary reserving pores includes structural fissures as well as karren pores and fissures. Structural fissures are further divided into five sub-types, with mesh and high angles fissures being dominant. Generally speaking, volcanic rock reservoirs are characterized by double media of pores and fissures with average porosity of 9.5% and matrix permeability of 1+10-3 m2. Though matrix material from basalt is better than trachyte, the pore throats of trachyte reservoirs are betterdeveloped than basalt in respect of pore structures; the overflow reservoirs have the best petrophysical conditions in trachyte and then the expulsion facies is the next. The volcanic reservoirs of this area is divided into type I and II based on reservoir classification criteria.3. Through rock mechanics analysis, basalt has the most compression strength, while that of trachyte is relatively weaker. Generally speaking, extensional fractures are developed in the basalt while extensional and shear fractures are developed in the trachaye. From the view point of volcanic rock cracking fashion and occurrences, two sets of conjugated fracture are formed in the process of tectonic movement of volcanic rock in the Eastern Depression. The fracture that is perpendicular to the major axis of the Eastern Depression is better developed than the fracture that is parallel with the major axis of the Eastern Depression. Two sets of fractures that are due to different direction cut each other, which enables that the fractures in the volcanic rock are in good communication, providing effective storing space for hydrocarbon. The fractures in trachyte are better developed than that in the basalt. Multi-stage regional faulting activities and volcanic eruption with multi-times of forcing generate favorable conditions for the fracture development of the volcanic rock in the Eastern Depression.4. According to lithochemistry properties of volcanics, starting with logging evaluation mechanism, a method of identifying lithology by radioactive logging is set up; on basis of core analysis data, log response of reservoir petrophysical properties is analyzed, thus providing basis for evaluating reservoir using logging data; on basis of testing data, combining with log imaging around wells, comprehensive classification criteria of volcanic reservoirs and porosity interpretation model are established.5. Starting from petroleum geological conditions in Eastern Depression, based on structural and sedimentary evolution analysis, reservoir form...
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