This paper discussed the forming conditions of large marine gas fields and gas field clusters in Sichuan Basin.Based on comprehensive analyses of structure and lithofacies

we discussed the control of the Indosinian and Caledonian paleouplifts on the marine petroleum accumulation.There are significant changes in exploitation targets in the Sichuan Basin

from anticlinal gas fields in the early stage to large gas fields correlated with porous reservoirs of bank facies

and to composite large gas fields related with peleouplifts now.In the first stage of exploration

small gas field clusters were found in Luzhou peleouplift.In the second stage

the Carboniferous porous gas reservoirs were discovered in eastern Sichuan Basin.In the third stage

the Wubaiti large gas field and gas field cluster were discovered in the Kaijiang paleouplift.In the fourth stage

medium-to-large gas field clusters represented by Puguang gas field were found in the Permian and Triassic reservoirs of reef-shoal facies.Recently

several highly-productive wells have been successfully completed in the Sinian Dengying Formation and the Lower Cambrain Longwangmiao Formation in the Leshan-Longnvsi paleouplift.The favorable superimposition of reservoirs

paleostructures and modern structures makes it possible to form giant gas field in this area.