There are a number of sets of source rocks, a number of hydrocarbon source area, multistage hydrocarbon generation and multistage hydrocarbon accumulation in the middle part of the West Sichuan Depression and it also experienced a number of tectonic stages adjustment and havoc. On it’s vertical,  multiple sets of sourcereservoir-cap assemblages gave birth to multilayer gasbearing series. According to the results of gas carbon isotopic analyses, part of upper Triassic series Xujiahe Formation’s gas ethane carbon isotopic have obvious negative skewness characteristics in this area. Through the analysis of core observation,  micrograph,  elements,  pyrolysis and so on, the authors see reservoir asphalt fillings have many characteristics such as multitude types,  several shapes of distribution,  a more clear boundary and so on.