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四川盆地震旦系—下古生界位于叠合盆地底部,其保存条件和烃源条件均佳,优质储层的形成与保存是油气能否成藏的关键。通过岩石学、流体地球化学等手段研究了四川盆地震旦系—下古生界优质储层形成与保存机理。研究结果表明:震旦系—下古生界滩相沉积环境普遍有利于早期优质储层的形成,而膏溶作用与表生岩溶作用是该时期早期优质储层的主要形成机理。另外,适时的油气充注、适宜的构造位置、相对稳定的构造、较少的流体混合、弱的水—岩反应及较低的含油饱和度等是早期优质储层的保存机理。震旦系—下古生界后期优质储层的形成机理则主要有深埋岩溶作用及有机酸导致的重结晶和构造挤压破裂作用等。
The Sinian-Lower Paleozoic in the Sichuan Basin is located at the bottom of the superimposed basin with good preservation conditions and hydrocarbon source conditions. The formation and preservation of high-quality reservoirs is the key to whether hydrocarbons can accumulate. Through the methods of petrology and fluid geochemistry, the formation and preservation mechanisms of high-quality Sinian-Lower Paleozoic reservoirs in the Sichuan Basin were studied. The results show that the depositional environment of the Sinian-Lower Paleozoic beach facies generally favors the formation of early high-quality reservoirs, whereas the gypsum dissolution and epikarst karstification are the main formation mechanisms of high-quality reservoirs in this period. In addition, timely reservoir preservation, proper structural position, relatively stable structure, less fluid mixing, weak water-rock reaction and lower oil saturation are the preservation mechanisms of early high-quality reservoirs. The Sinian-Lower Paleozoic formation of high-quality reservoirs mainly includes deep-burial karstification and recrystallization and tectonic crushing caused by organic acids.