The Sichuan Basin is the biggest petroliferous basin in southern China and also one of the most impor-tant superimposed basins in China.Its specific petroleum geologic conditions of marine facies can be expounded in the following three aspects:(1) superimposed basin

(2) carbonate reservoir

and(3) natural gas.The Basin is a superimposed basin.Its basement can be divided into three parts.The sedimentary cover had undergone three evolutionary stages

including platform (marine facies)

basin (continential facies)

and folding& uplifting.Based on the basement and its structural features

the present basin can be divided into four divisions with eleven blocks.The basin contains marine carbonate reservoirs characterized by low porosity and permeability

highly-de-veloped fractures and strong heterogeneity.The basin is rich in natural gas

most of which is cracked gas from oil and is characterized by multiple sources

migration phases

and occurrences.In summary

the controlling factors and their functions for the marine oil & gas distribution in the basin can be boiled down to the following three points:1) hydrocarbon source rocks control the favorable areas of gas occurrence;2) reservoir quality controls the layers of gas accumulation;and 3) traps control the structural locations of gas accumulation.A diversified explo-ration strategy is therefore required to deal with the great variety of carbonate oil and gas pools in Sichuan Basin.