四川盆地中二叠统天然气成藏特征及巨大勘探前景

Natural gas accumulation characteristics and great exploration potential of the Middle Permian in the Sichuan Basin

近年来,在四川盆地中二叠统钻遇孔隙型白云岩储层,获得一批高产井,呈现出良好的勘探前景,但其勘探潜力如何,能否成为四川盆地继安岳气田之后又一个万亿方大气区亟待明晰。通过对烃源岩特征、沉积特征、储集特征以及成藏模式等方面的深入研究认为,中二叠统具备3套优质烃源岩供烃、孔隙型储层发育、封盖条件好的优越成藏条件,发育自生自储型和下生上储型两套成藏组合。中二叠统发育块状孔隙型白云岩储层和孔隙型灰岩岩溶储层,分布面积大,其储集性能和单井测试产量与安岳气田灯影组相当,勘探潜力巨大,是四川盆地下步寻找万亿方大气区的主要层系。

In recent years porous dolomite reservoirs are drilled in the Middle Permian of the Sichuan Basin,and several high-yield wells with good exploration prospects are obtained.However,the exploration potential of the Middle Permian is still unclear and it is critical to know if it beholds another trillion cubic meter-scale natural gas field in the Sichuan Basin,in addition to the Anyue natural gas field.Through in-depth analysis of the source-rock,sediment and reservoir characteristics as well as accumulation models,we find the Middle Permian possesses superior reservoir-forming characteristics—including high-quality hydrocarbon source rock,porosity reservoir development and good well-sealing conditions—and two source-reservoir configuration types—“self generation-self storage”and“lower generation-upper storage”.The Middle Permian develops massive porous dolomite reservoirs and porous limestone karst reservoirs over a large area,and its reservoir capacity and single-well testing production are equivalent to that of the Dengying Formation in the Anyue natural gas field indicating great exploration potential.We believe the Middle Permian is the main stratum to search for the next giant natural gas field in the Sichuan Basin.