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通过对烃源条件的研究,认为四川盆地加里东古隆起下古生界震旦系气藏的天然气具有烃类组成差别小、非烃组成差别大、甲烷碳同位素值差别大的特征.储层沥青和烃源岩中生物标志化合物如正构烷烃、三环萜烷、五环三萜烷、10-脱甲基藿烷和甲基藿烷等,均具有较高的一致性,确证了震旦系的油气主要来自下寒武统筇竹寺组的泥质岩.烃源岩厚度大、丰度高、类型好、生烃强度大、供烃时间长,可以为古隆起带大中型圈闭提供充足的天然气.震旦-寒武系的储层以古岩溶型为特征,古岩溶作用强烈,存在着两种类型的古岩溶发育模式、八种次生孔隙、三种洞穴及五种裂缝.储层基质具有低孔低渗特点,储集类型主要是裂缝-孔洞型,储层在纵横向上的分布较稳定.古隆起天然气具有早、晚期聚集的特征,其成藏也可划分成早期成藏和晚期成藏两种类型.综合分析认为,古隆起天然气成藏需要具备“三高一强一联系”的控制因素:“三高”是指圈闭的高封存能力、较高的构造部位、较高的圈闭隆起幅度;“一强”是指圈闭要有较强的构造形变程度;“一联系”是指现今圈闭与早期形成的古油气藏具有密切联系.“,”Through a research on the conditions of hydrocarbon sources,it is considered that the natural gas in the Sinian reservoir,Lower Paleozoic,of the Caledonian ancient uplift in Sichuan Basin is of the properties of a little difference in hydrocarbon components,a great difference in nonhydrocarbon components and a vast difference in methane carbon isotope ratios.The biomarkers as the normal alkane,tricyclic terpane,pentacyclic triterpane,10 demethylhopane and methylhopane,etc.,in reservoir bitumen and hydrocarbon source rocks are all of high consistency,which surely indicates that the oil and gas mainly came from the argillaceous rocks in Qiongzhusi Formation of Lower Cambrian.Sufficient natural gas may be provided for the large and medium sized traps in the ancient uplift zone because of the large thickness,high abundance,ideal type,great hydrocarbon generating strength and long time hydrocarbon supply of the hydrocarbon source rocks.The reservoirs in Sinian Cambrian are characterized by palaeokarst type with strong palaeokarstification,being of two kinds of palaeokarst development models,eight kinds of secondary pores,three kinds of cavities and five kinds of fractures.The matrix of the reservoirs is possessed of the properties of low porosity and low permeability,the type of the reservoirs is mainly the fracture pore type and the distribution of the reservoirs is relatively stable in both vertical and lateral.The natural gas in the ancient uplift is of the properties of the early accumulation and late accumulation and correspondently two types of reservoir formation,i.e. early reservoir formation and late reservoir formation may be divided.Through comprehensively analyzing it is thought that the gas reservoir formation in the ancient uplift must be possessed of the controlling factor of “Three High,A Strong and A Relationship”.“Three High” means the high seal capacity of trap,relatively high structural portion and the relatively high uplifted height of trap;“A Strong” means a relatively strong structural deformation of the traps;and “A Relationship” means that a close relationship was found between the existing traps and the ancient reservoirs formed in the early stage.