Abstract: Xushen gas field is a typical tight volcanic gas reservoir located in Songliao Basin.With the development of gas reservoir in depth,water breakthrough in wells appears,and the intensive water invasion and rising gas-water ratio have severely restricted the efficient development of volcanic gas reservoir.Therefore,the understanding of inner gas-water distribution,along with its major controlling factors,has becoming a key in enhancing gas well productivity.In the study area,the gas-water distribution is complex in the volcanic gas reservoir,and characterized by "gas on top and water at bottom" overall.Besides,volcanic edifice is the elementary cell of gas-water distribution; there is no unified gas-water interface throughout the study area,while more than one gas-water systems may exist in the same volcanic edifice; and different gas-water systems may share a gas-water interface.Based on the description of volcanic edifices in the Yingcheng Formation,we systematically analyzed the gas-water distribution characteristics of,and clarified the major factors controlling the gas-water distribution in the tight volcanic gas reservoir in Xushen gas field,using production test,as well as some static data in terms of physical property,mercury intrusion porosimetry (MIP) and thin section.The results show that the source rock distribution controls the macroscopic gas-water distribution in the volcanic gas reservoir in the Yingcheng Formation,while the volcanic edifice and structure have jointly had an influence on the accumulation and adjustment of gas,and the complicated microstructure of volcanic rocks is a key to gas-water fractionation in the reservoir.

Key words: gas-water distribution, volcanic edifice, volcanic gas reservoir, Yingcheng Formation, Xushen gas field, Songliao Basin