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四川盆地震旦系-下古生界具有三套泥质油系烃源岩,具有很好的生油潜力和生烃强度。受加里东隆升作用的影响,烃源岩有二次生、排烃的特征,三叠纪是主要圈闭形成期和二次生油的主峰期,大量的石油运聚至乐山-龙女寺古隆起范围内形成震旦系-下古生界古油藏。随着古油藏埋深的增加,温度和压力的增高,石油裂解成天然气,古油藏自身形成气源,在原地系统形成古气藏。这一过程持续到喜马拉雅期,之后受喜马拉雅运动的影响,强烈隆升和剥蚀,圈闭重新调整,气藏重新分配,最终形成现今气藏。因此,四川盆地震旦系-下古生界天然气的成藏过程是一个古油藏→古气藏→现今气藏的过程,具有生排差异、多期运聚、早聚晚藏的特征。
The Sinian-Lower Paleozoic in the Sichuan Basin has three sets of muddy oil source rocks with good potential for oil generation and hydrocarbon generation. Affected by the Caledonian uplift, the source rocks have the features of secondary generation and hydrocarbon expulsion. The Triassic is the main trap formation period and the secondary peak of secondary oil generation. A large amount of oil is transported to Leshan-Dragon Girl Formation within the Temple paleo-uplift Sinian - Paleozoic paleozoic reservoir. With the increase of burial depth of ancient oil reservoirs, the temperature and pressure increase, the oil is cracked into natural gas, and the paleo-oil reservoirs form gas sources by themselves to form ancient gas reservoirs in situ. This process continued into the Himalayan period, after the influence of the Himalayan Movement, a strong uplift and erosion, trapping readjustment, reservoir reallocation, and eventually the formation of today’s gas reservoir. Therefore, the gas accumulation process of the Sinian-Lower Paleozoic in the Sichuan Basin is an ancient reservoir → paleo-gas reservoir → present gas reservoir.