“进源找油”:论四川盆地非常规陆相大型页岩油气田

“Exploring petroleum inside source kitchen”:Jurassic unconventional continental giant shale oil &gas field in Sichuan basin,China

源岩油气规模快速发展,是中国能源结构转型的重要战略选项;陆相页岩油和气是中国源岩油气最具潜力的组成类型,是中国陆上未来"进源找油"最重要的突破对象。本文首次研判提出四川盆地侏罗系油和气发展,应尽快由常规构造-裂缝石油、致密灰岩与砂岩油向孔隙型页岩油气转变,重点阐述了大安寨段页岩油气4项新进展:①评价侏罗系4套富有机质页岩总生油量245×10^8t,石油总资源量172×10^8t,还有相当规模的天然气资源,既富油又富气,其中67%的油气资源集中在大安寨段;②大安寨段二亚段是侏罗系页岩油和气的"甜点段",黑色页岩厚度一般20~80m,TOC平均值大于2%,Ⅱ1~Ⅱ2型干酪根,Ro主体1.1%~1.4%,处于轻质油-凝析油气窗口,页岩储层孔隙度4%~6%,页理裂缝发育,脆性矿物含量一般在50%以上,压力系数1.2~1.8,滞留烃量多为100~200mg/g·TOC,油质较轻,地层埋深较浅,具备与北美页岩油气媲美的地质工程条件;③优选出页岩油气"甜点区"评价的3项核心参数(Ro、富有机质页岩厚度、埋藏深度),评价出大安寨段二亚段页岩油"甜点区"主要分布在盆地中北部地区,页岩厚度20~50m,面积约2×104km2;④提出了加快页岩油和气以水平井体积压裂为核心的风险勘探和开发试验、加强全层系资源评价、加速准备先导试验技术方案等建议,力争推动侏罗系孔隙型页岩油和气突破发现。四川盆地侏罗系陆相页岩油和气新认识,可能为真正开启侏罗系源岩油气"进源找油"、规模开发新征程提供重要的理论依据。

The rapid and scale development of source rock oil & gas is an important strategic option for the transformation of energy structure in China. Continental shale oil & gas is the most potential component type of source rock oil & gas in China, and the most important breakthrough target of "exploring petroleum into source kitchen" in the future. For the first time this paper puts forward the riewpoint that the development of Jurassic oil and gas in Sichuan Basin should be transformed from conventional structure-fractured oil and tight limestone and sandstone oil to porous shale oil & gas as soon as possible. Four new developments of shale oil & gas in Daanzhai Member are emphatically expounded.(1) The total oil production of four sets of organic-rich shale in Jurassic system is 245×10^8t, the total oil resources are 172×10^8t, and there are also considerable natural gas resources, and 67% of the oil and gas resources are concentrated in Daanzhai Member.(2) The second sub-member of Daanzhai Formation is the sweet section of Jurassic shale oil & gas. The thickness of black shale is generally 20~80 m, the average TOC value is more than 2%, the kerogen type is Ⅱ1~Ⅱ2, the Ro is mainly 1.1%~1.4%, is in the light oil-condensate oil window, the porosity of shale reservoir is generally 4%~6%, the shale fracture is developed, the brittle mineral content is generally more than 50%, the pressure coefficient is 1.2~1.8, and the residual hydrocarbon amount is more than 100~200 mg/g·TOC, with light oil and shallow burial depth, has geological engineering conditions comparable to North American shale oil and gas.(3) Three core parameters(Ro, organic-rich shale thickness and burial depth) for evaluation of shale oil & gas sweet area were optimized. The sweet area of shale oil in the second sub-member of Daanzhai Member was mainly distributed in the north-central part of the basin, with shale thickness of 20~50 m and area of about 2×104km2.(4) Three suggestions are put forward, including speeding up the implementation of risk target exploration and development testing by horizontal drilling and stimulated reservoir volumn fracking, strengthening the resource evaluation of the whole strata and speeding up the preparation of pilot test technical schemes, to promote the breakthrough discovery of oil and gas in Jurassic porous shale. The new understanding of Jurassic continental shale oil & gas in Sichuan Basin will provide an important theoretical basis for truly opening up the new journey of Jurassic source rock oil & gas "exploring petroleum into source kitchen " and large-scale development.