川东北地区平安1井侏罗系凉高山组页岩油重大突破及意义

位于四川盆地东北部(简称川东北)古中央凹陷的平安1井在侏罗系凉高山组页岩获得百吨高产,实现了四川盆地凉高山组页岩油气勘探的重大突破。基于平安1井的勘探成果,系统分析了川东北地区凉高山组页岩油成藏条件和下一步勘探方向。研究结果表明:平安1井突破层系为凉高山组湖相富有机质页岩,其岩石类型为长英质页岩,孔隙度平均值为2.06%,以粒间孔、晶间孔为主,微裂缝发育;TOC值为0.64%~1.35%,有机质类型以Ⅱ型为主,R o为1.51%~1.66%,脆性矿物含量为50.4%~54.8%。综合评价认为川东北地区在前陆盆地背景下,广泛分布的半深湖相页岩富含有机质,有利于页岩油气富集成藏。其中凉上段发育3套页岩,生烃能力强,演化程度高,整体为一套高质量烃源岩;保存条件好、地层超压、孔—缝体系发育,既是有效储层又是高效产层。平安1井的突破,展示了四川盆地侏罗系湖相页岩巨大勘探潜力,对加快四川盆地页岩油勘探起到了积极的推动作用。

Major breakthrough and significance of shale oil of the Jurassic Lianggaoshan Formation in Well Ping’an 1 in northeastern Sichuan Basin

Well Ping’an 1,located at the paleo central sag in northeastern Sichuan Basin,achieved a high shale oil production of 100 tons from Lianggaoshan Formation,indicating a major breakthrough of shale oil and gas of Lianggaoshan Formation in Sichuan Basin.Based on the exploration results in Well Ping’an 1,the main controlling factors for shale oil accumulation and exploration orientation of Lianggaoshan Formation in northeastern Sichuan Basin are systematically analyzed.The results show that the shale oil reservoir in Well Ping’an 1 is lacustrine organic rich shale and the rock type is felsic shale.The average porosity is 2.06%,dominated by intergranular pores and intracrystal pores,with micro fractures developed;TOC ranges from 0.64%-1.35%,and TypeⅡorganic matter is dominant.R o is in the range of 1.51%-1.66%.The content of brittle minerals is 50.4%-54.8%.The comprehensive evaluation indicates that the widely distributed semi deep lacustrine shale is rich in organic matter in foreland basin in northeastern Sichuan Basin,which is conducive to shale oil and gas accumulation.Among them,three layers of shale are developed in the Upper Lianggaoshan Formation,with strong hydrocarbon generation capacity and high degree of thermal evolution,which is a set of high-quality source rock as a whole;In addition,it has good preservation conditions,formation overpressure and well-developed pore-fracture system,which enable to serve as an effective reservoir and a high-efficiency production layer.The breakthrough in Well Ping’an 1 shows the great exploration potential of the Jurassic lacustrine shale,and plays a positive role in accelerating shale oil exploration in Sichuan Basin.