Abstract: Wolonghe Gas Field is the first gas field discovered in China and has the multiple source rocks,multiple reservoirs and multiple traps.According to the component and carbon isotopic compositions of gases from three main reservoirs including the Lower Triassic Jialingjiang Formation,the Middle Carboniferous Huanglong Formation and the Lower Permian,the origin of natural gas and the main source rocks were determined in combination with the distribution of source rocks.The gases in the Lower Triassic Jialingjiang Formation are mainly composed of coal-formed gases from the Upper Permian humic source rocks and a slight mixture of oil-type gases from Silurian sapropelic source rocks.The gases in the Middle Carboniferous Huanglong Formation are mixture of gases from Silurian sapropelic source rocks with different maturity.The gases in the Lower Permian are dominated by oil-type gases,which derived from Silurian source rocks mixed with a little gas from the Lower Permian carbonates.Besides,there are a lot of oil-cracked gases in Wolonghe Gas Field.Moreover,the main controlling factors of Wolonghe Gas Field include the high quality source rocks lying in the gas-generating center and surrounding area,the excellent reservoirs,traps related to the paleo-uplifts,and late-period accumulation.

Key words: Wolonghe Gas Field, origin of natural gas, source rock distribution, oil-cracked gas, gas reservoir, main controlling factors

摘要： 对卧龙河气田3套主要产层下三叠统嘉陵江组、中石炭统黄龙组和下二叠统的天然气组分及同位素组成特征进行了分析,结合烃源岩分布规律,确定了各层系天然气成因及主力气源。其中下三叠统嘉陵江组天然气主要以上二叠统龙潭组腐殖型烃源岩生成的煤成气为主,以志留系腐泥型源岩生成的油型气为辅;中石炭统黄龙组天然气主要由志留系烃源岩生成的不同期次的油型气混合而成;下二叠统天然气除了志留系源岩生成的油型气外,还有少量下二叠统碳酸盐岩生成的油型气。另外,卧龙河气田还存在大量原油裂解气。卧龙河气田的形成与该区多套优质烃源岩发育、处于生气中心及其周缘、优质储层发育、古隆起构造背景和晚期成藏等多种因素密切相关。

关键词: 卧龙河气田, 天然气成因, 烃源岩分布, 原油裂解气, 天然气藏, 主控因素