四川盆地湖相页岩气源-储配置类型及评价

四川盆地湖相页岩气勘探已在建南、涪陵和元坝地区中-下侏罗统获得良好的页岩气显示和工业气流，展示了良好的勘探前景。与海相富有机质页岩相比，湖相泥页岩具有沉积相变快、岩相类型多样（互层、夹层）、有机质丰度较低、储集非均质性强和源-储配置复杂的特点。依据不同的岩相类型，将湖相泥页岩划分为源夹储、源储互层2大类4亚类源-储配置类型。采用有机地化、微观储渗实验及纳米CT等方法技术，在对每一种源-储配置类型进行生烃、储集和可压性特征研究的基础上，将不同的源-储类型作为独立的“源储体”单元，创建了与湖相多类型源-储配置特征相适应的源储体系数进行评价。评价结果表明，碳酸盐湖泊沉积的页岩与介屑灰岩互层型具有良好页岩气生烃、储集、渗透和可压裂配置条件，有利于页岩气的形成和改造，是湖相最有利的源-储配置类型；页岩夹介壳灰岩源-储配置型具有良好页岩气生烃和储集条件，但渗透性和可压性较差，为较有利源-储配置类型，上述两种类型可作为湖相页岩气开发的优选层段。

Types and evaluation of the source-reservoir configuration of lacustrine shale gas in the Sichuan Basin

Exploration of the lacustrine shale gas in Sichuan Basin has discovered strong gas shows and/or commercial gas flow in the Middle and Lower Jurassic of Jiannan,Fuling,and Yuanba areas,east of Sichuan,which are prospective areas for petroleum exploration.Compared with organic-rich marine shale,the lacustrine shale is characterized by fast change of sedimentary facies,diversity of lithofacies(interbed and alternating beds),low abundance of organic matters,strong reservoir heterogeneity and complex source-reservoir configuration.According to the types of lithofacies,the lacustrine shale can be divided into two types of source-reservoir configuration,namely the type of “reservoir interbedded within source rocks” configuration and the type of “source-reservoir alternating” configuration,which can be further subdivided into four subtypes.Through such methods as organic geochemistry,microscopic storage and permeability experiments and nano CT,we stu-died the characteristics of hydrocarbon generation,storage capacity and fracturability for each type of source-reservoir configurations,and established the evaluation model for source-reservoir coefficients conformable to the characteristics of the lacustrine source-reservoir configurations of various types,with each type as an independent “source-reservoir” unit.The evaluation results show that the source-reservoir configuration of the alternating shale and shell limestone deposited in a carbonate lake has favorable conditions for hydrocarbon generation,shale gas storage,permeability and fracturability,beneficial to the formation and stimulation of shale gas reservoirs,thus functions as the most favorable type of source-reservoir configuration of the lacustrine facies.In comparison,the source-reservoir configuration with shell limestone interbedded within shale has favorable hydrocarbon generation and reservoir conditions,but poor permeability and fracturability,thus is fair in quality.The above two types can be taken as the preferred layer for the development of lacustrine shale gas.