Research of volcanic reservoir characters and hydrocarbon accumulation models

he history of volcanic reservoir exploration has been already 120 years,after the three development stages which are the accident found,the initial exploration and in-depth study,volcanic rocks have been important areas from the restricted area in the oil and gas exploration.Although volcanic reservoir is in a small proportion of the total oil and gas reservoirs in the world,volcanic reservoir has shown good prospects,and been the new growth point,attracted more and more attention in oil and gas exploration sector.Researching volcanic reservoir,the most important issue is the lithologies and facies.In this article,domestic and foreign classification schemes of volcanic facies is listed,and volcanic reservoir space has been divided into original porosity,original cracks,induced porosity and induced cracks four categories,13 small classes.The accumulation mode of volcanic reservoir has been divided into lithological accumulation mode,structural accumulation model,structural-lithological accumulation model,weathering crust accumulation mode.There are four key reservoir-forming factors of volcanic reservoirs:structural conditions control the volcanic activities that decide the distribution of volcanic rocks and structural movement can improve reservoir performance immensely;volcanic lithologies and volcanic facies controls the types of reservoir space and development degree of the fractures;space-time matching condition between reservoir formation and hydrocarbon expulsion is the key factor;weathering leaching play an important role on making better the reservoir space.Gravity prospecting and magnetic prospecting are taken much count at home and abroad owing to the characteristics of volcanic rocks on density and magnetic aspects.In volcanic reservoir interpretation,forward modeling,seismic attributes analysis,wave impedance inversion and coherence analysis are the most popular and useful techniques.For the complexity of volcanic reservoir,to establish a targeted research approach for volcanic reservoir,must be guided by the geological theory,combined with core,gravity, magnetic,logging and seismic data,so we can comprehensively assess the volcanic reservoir characteristics and spatial distribution,and guide the oil and gas exploration of volcanic reservoir.