The Potential Of Shale Gas Resources And Geochemical Characteristics In Longmaxi Formation Of Fuling Area

With the increasingly prominent contradiction between supply and demand of energy,oil and gas exploration and development fields gradually towards the direction of coalbed methane,shale gas,tight sandstone gas and other unconventional oil and gas development.The lower Silurian Longmaxi formation have developed a high quality marine source rock in Jiaoshiba area of Sichuan Basin.As long as the deep for exploration and development,shale gas exploration wells have been gaining industrial gas flow and showing a good shale gas exploration prospect in South-East Sichuan Basin of the lower Paleozoic.This paper takes the organic geochemistry,sedimentology,logging geology theory methods and so on to system reach the marine shale gas geology characteristics and resource potential for Longmaxi formation in Jiaoshiba area,and preliminary estimates shale gas resource and comprehensive evaluation of shale gas resource potential of the Longmaxi group.Through core observation and well logging data analysis,the Longmaxi group are mainly muddy shallow shelf facies and has a large set of dark grey,film of mudstone,carbonaceous mudstone clip a thin layer of argillaceous siltstone,further in Jiaoshiba area.shelf can be divided into the deep,and the shallow shelf subfacies and microfacies,such as mud flat,sand flat.Stable formation deposition,shallow buried and effective shale has large thickness,distribution is quite stable either,It's helpful for the preservation of shale gas.According to the geochemical data of core shale rock in Jiaoshiba area,the Longmaxi group has high residual organic carbon content and kerogen type is given priority to with?type,shale thermal evolution of organic matter in high-over mature stage and have good ability for hydrocarbon generation;Siliceous brittleness and mineral content is high.So it has a good brittleness.Clay mineral content is priority to illite and montmorillonite layer,along with the times of chlorite,excluding montmorillonite.Illiteand kaolinite is advantageous to the formation of inorganic microporous or intergranular hole,and with the increase of depth,clay mineral content is lower,reservoir pressure can be good.Combined with well logging,mud logging and core analysis,the Longmaxi shale has a better hydrocarbon showings,free gas and adsorbed gas are existing in same time.There are two main kinds of microscopic pore structure,high pore and low permeability,low porosity and low permeability.Reservoir types are mainly composed of micro pore and fracture,logging interpretation found that bedding joint development also can be used as reservoir space for shale gas.Finally considering various geological parameters by the volumetric method and volume method to calculate the longmaxi group shale gas resource inJiaoshiba area,a set of shale gas resource is(750.11~869.07)×10~8m~3,resource abundance(4.32~4.91)×10~8m~3/km~2,it is the main objects for shale gas efficiency exploit and develop.