Abstract: 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.

Key words: lacustrine facies, lithofacies, source-reservoir configuration type, source-reservoir coefficient, shale gas, Sichuan Basin