MAIN MODELS AND DISTRIBUTION PATTERNS OF GAS-RESERVOIRS IN LARGE-MEDIUM GAS-FIELDS OF CHINA

Based on characteristics and trap types of gas reservoirs in large and medium gas fields in China, 4 gas reservoir models have been establis hed: (i) structural trap gas reservoir model I, formed earlier than or simutaneously with generating of gases; (ii) structural trap gas rese rvoir model II, formed later than generating of gases; (iii) fossil we athered residuum gas reservoir model; and (iv) mud diapir abnormal tem perature and pressure gas reservoir model. Distribution patterns of la rge-medium gas fields are described with the concept of ''sealed compa rtment'' It is concluded that the inner-compartment area, marginal are a of the compartment and the areas between two overlapped sealed compa rtments are the most favourable areas for discovering large-medium gas fields.