Identification of lithology and fluids of acid volcanic rocks:A case study of volcanic reservoirs in Xushen gas field

This paper presents many difficulties in logging evaluation on volcanic reservoirs,such as complicated lithology,complex and uncertain fluids and the impact of lithology even greater than that of reservoir fluids on logging curves.Taking the volcanic reservoir in the Xushen gas field,Songliao Basin,as a study case and through a deep investigation into the relationship among lithology,petrophysical properties,gas production and logging parameters of volcanic rocks by logs,mud logging,testing and core data analysis,this study identified rock components by conventional logging as well as rock structures by imaging logging and discriminated volcanic lithology in combination with the ECS log.Based on this,the conventional logging in combination with the specific logging was established to identify the fluids,which had good effects on evaluating the proved reserves of natural gas in this gas field and this will be a reference for evaluating the similar volcanic reservoirs in other areas.