Reservoir characteristics of deep volcanic rocks and prediction of favorable areas in Changshen gas field In the south of Songliao basin

With the successful exploration for volcanic rock reser- voir in Changling fault sag,the research on deep-buried volcanic reservoir is an important new field of oil and gas ex- ploration in south Songliso Basin.At first,the characters of petrology,reservoir space types and the characters of physi- cal property are analyzed.And then,the characters of seis- mic reflection and velocity are also analyzed,which is a premise of reservoir prediction.Volcanic rocks at the inter- est area can be classified into two classes as lava and volca- noclastic rock and eight kinds.The reservoir space of volca- noclastic rock is complicated,of which the emposieu or the fissure is the most important reservoir space.Comprehensive analysis on regional geology,well drilling and testing data and seismic data shows that the gas pool of the third stage in Changshen gas field is a structural--lithologic pool,whose formation is subject to many factors as the structure,physi- cal property,lithology and lithofacies.It is pointed out that the top volcanic rock explosion facies and the band of gas pore growing on the top volcanic overflowing facies are the favorable facies in the forth eruption stage.At last,the dis- tribution of favorable zone basing on seismic attribute and in- version is predicted,which provides directions for explora- tion and development of deep volcanic reservoir at the area.