Analysis of the Accumulation Conditions for Volcanic Gas Reservoirs: A Case from Deep Yingcheng Formation, Southern Part of Songliao Basin

Volcanic gas reservoir in deep Southern Songliao Basin has became source for incremental oil and reserves. Due to the low degree of exploration, study on the accumulation condition for volcanic gas reservoir is insufficient, to some extent, influencing the effectiveness of exploration. In this paper, the accumulation conditions for volcanic gas reservoir have been analyzed systematically including the source rock conditions, reservoir conditions, sealing conditions, conducting conditions and trap conditions. The study results show that large-scale coal-bearing strata in Shahezi Formation can provide sufficient gas for volcanic gas reservoir: the fracture systems in deep volcanic rocks can communicate with the earlier developed pores, fractures and caves, forming good reservoir and flow space; It contains multiple rock types with good preservation condition, the mudstone in first member of Quan Formation is better regional seal. Mudstone in third and fourth member of Denglouku Formation and Shahezi Formation are favorable local seals, with good seal capability for volcanic rocks gas accumulation in Yingcheng Formation. ontains three types of transporting pathways: permeable formation, unconformity and fault.