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川西地区侏罗系为一套巨厚陆相红色碎屑岩沉积，不具备生烃能力，但相继发现了一批储量丰富、分布广泛的侏罗系气藏。按烃类来源，这些侏罗系气藏可分为：以上三叠须五段生油岩为气源的近源型气藏和以须二气藏为气源的远源型次生气藏。前者按储层性质则又可细分为致密型和常规型两亚类气藏。气藏类型制约各自的规模、储量和勘探方法。类型划分明确了该区侏罗系气藏的成因。从形成机制出发，认为以须五段为气源的近源型气藏是川西南部、中部的主要侏罗系气藏，是本区今后寻找大中型浅层气藏的主要方向；并提出了对已知侏罗系气藏的扩大勘探，评价出名山－百丈－大塘铺一带是川西地区寻找近源型气藏最有利地区。

TYPES OF THE JURASSIC GAS RESERVOIRS IN WEST SICHUAN AND THEIR PROSPECTS

The Jurassic in West Sichuan is composed of a series of reddetrital deposits with a giant thickness，having no source potential．However，a lot of wildspread Jurassic gas reservoirs with abundant reserves were found one by one in this region．According to hydrocarbon sources，the Jurassic gas reservoirs may be divided into the near-source gas reservoirs in which the natural gas came from the fifth member of Xujiahe Formation of Upper Triassic and the secondary far-source gas reservoirs in which the natural gas came from the Xu-2 gas reservoirs．The near-source gas reservoirs may be also subdivided into two subtypies of gas reservoirs，as the tight ones and the conventional ones．The scale，reserves and exploration method are dependent upon the type of the gas reservoir．Through the division of the types，the geneses of the Jurassic gas reservoirs in the region are defined．On the basis of the formation mechanism，it is considered that the near-source gas reservoirs are the principal Jurassic gas reservoirs in the south and central parts of West Sichuan，being the major targets of prospecting for large- and medium-sized shallow gas reservoirs and it is suggested to expand the exploration on the basis of the known Jurassic gas reservoirs．Through evaluation it is proposed that the Mingshan-Baizhang-Dantanpu areas are the most beneficial regions of prospecting for the near-source gas reservoirs in West Sichuan．