四川盆地大中型气田形成的主控因素及勘探对策

作为世界上最早开发利用天然气的地区，四川盆地油气资源丰富，已经发现了28个工业油气产层，建立起了我国第一个完整的天然气工业体系。在对四川盆地大中型气田形成的主控因素分析的基础上，进一步明确盆地大中型气田的勘探有利领域与方向。四川盆地具有裂陷槽控烃、古隆起控藏、侵蚀面控储、盖层控保、断裂控储的天然气富集特点。近源供烃、大型古隆起聚集、侵蚀不整合面溶蚀碳酸盐岩有效储集、区域稳定盖层保存、深大断裂输导等是天然气得以富集的主控因素，大中型气田的勘探重点应该围绕三大古隆起、两个裂陷槽以及基底断裂展开，通过优选，认为海相碳酸盐岩领域中震旦系—下古生界、二叠系—三叠系高能相带及三叠系雷口坡组，陆相致密碎屑岩，二叠系火成岩以及页岩气等领域是下步大中型油气田的有利勘探领域。

Controlling factors and countermeasures for exploring large and medium-sized gas fields in Sichuan Basin

The Sichuan Basin has been known to be rich of oil and gas resources, and after the exploration and development for more than 70 years, oil and gas reservoirs (mainly gas reservoirs) have been widely discovered in 28 strata, and the first complete gas industrial system has been built in this basin. The main constraint factors for the formation of large and medium-sized gas fields in the Sichuan Basin were discussed in this paper, and some favorable exploration targets were proposed. The enrichment of natural gas in the Sichuan Basin has several characteristics including the generation, accumulation, reservoir, preservation and migration of natural gas which were controlled by rift troughs, paleo-uplifts, erosion surfaces, cap rocks and faults, respectively. Near-source hydrocarbon supply, hydrocarbon accumulation in paleo-uplifts, effective reservoirs caused by the dissolution of carbonate rocks at the erosion surface of unconformity, regional stable preservation by cap rocks and migration through deep and large faults were the main controlling factors for natural gas enrichment. Therefore, the exploration activity for large and medium-sized gas fields was suggested to focus on 3 paleo-uplifts, 2 rifted troughs, and the basement faults in the Sichuan Basin. Through optimization, it was concluded that the Sinian to Lower Paleozoic strata, the high-energy phase band of Permian-Triassic and the Leikoupo Formation of Triassic in the marine carbonate area, the tight continental clastic rocks, the volcanic rocks in Permian and the shale gas areas are the favorable fields for further exploring for large and medium-sized gas fields.