四川盆地西南缘五峰组-龙马溪组页岩气形成条件与有利区优选

利用四川盆地西南缘志留系龙马溪组最新钻井、露头资料及样品分析结果,从富有机质泥页岩区域分布、岩性、有机地球化学特征、储层特征、含气性、地层压力等方面,重点研究四川盆地西南缘龙马溪组页岩气形成条件与有利区优选。研究发现,五峰组—龙马溪组页岩具有有机质含量高(TOC 0.12%~6.49%,平均2.06%)、有效厚度大(普遍大于30m)、热演化程度高(Ro2.62%~2.80%)、脆性矿物含量高(56%~92%)、孔隙度较高(0.50%~11.36%,平均3.85%)等特征,钻井岩心现场解析气量最大值达3.38 m3/t、埋深适中(浅于3500m),这些条件均有利于页岩气的形成与富集。综合对比研究结果表明,云南云荞、木杆、高桥地区是四川盆地西南缘页岩气勘探的3个有利区。

Genetic conditions of the shale gas and delineation of the favourable areas in the Wufeng Formation-Longmaxi Formation on the southwestern margin of the Sichuan Basin

The genetic conditions of the shale gas and delineation of the favourable areas in the Wufeng Formation-Longmaxi Formation on the southwestern margin of the Sichuan Basin are dealt with in detail on the basis of distribution, lithology, organic geochemical signatures, reservoir physical properties, gas contents and stratigraphic pressures of organic matter-rich shales indicated by the new data of outcrops and core samples. The Wufeng Formation-Longmaxi Formation on the southwestern margin of the Sichuan Basin are characterized by high organic carbon contents (TOC=0.12%-6.49%, an average of 2.06%), great thickness (> 30 m), highly thermal evolution (R₀=2.62%-2.80%), high brittle mineral contents (56%-92%), high porosity (0.50%-11.36%, an average of 3.85%), high gas contents (> 3.38 m³/t), and shallow burial depths (< 3500 m), which are favourable for the generation and enrichment of the shale gas. The Yunqiao, Mugan and Gaoqiao areas in Yunnan are delineated as the favourable areas for the exploration of the shale gas on the southwestern margin of the Sichuan Basin.