Study on Micropore Structure Characteristics of Longmaxi FormationShale Gas Reservoirs in the Southern Sichuan Basin

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  • 1.State Key Laboratory of Coal Resources and Safe Mining,China University of Mining andTechnology (Beijing),Beijing 100083,China;
    2.College of Geoscience and Surveying Engineering,China University of Mining andTechnology (Beijing),Beijing 100083,China;
    3.State Key Laboratory of Petroleum Resource and Prospecting,China University ofPetroleum(Beijing),Beijing 102249,China;
    4.College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China

Received date: 2013-11-06

  Revised date: 2014-03-22

  Online published: 2014-06-10

Abstract

Based on the scanning electron microscopy,high pressure mercury-injection,N2 and CO2 gas adsorption methods,the micropore characteristics and structures of shale samples from the Lower Silurian Longmaxi Formation marine shale gas reservoirs in the southern Sichuan Basin were studied,and their influencing factors of pores development were also discussed.The results showed that there are various types of micropores in the Longmaxi Formation marine shale samples in the southern Sichuan Basin,mainly including clay inter-granular pore,pyrite crystal particle pore,bioclast inter-granular pore,carbonate grain dissolved pore,particle edge pore and organic pore.The main pore types in these shale samples are micropores and mesopores.A large amount of micro-nano scale pores are developed in the organic-rich shales,which provided storage space for shale gas.The structure of shale pores is dominated by the parallel-plate pores,cylinder pores and mixed pores.The sizes of these pores mainly occur in a range of 0.4-1nm and 3-20nm.In the Longmaxi Formation marine shale,the micropore and mesopore account for 78.17% of the total volume of pores and 83.92% of the total specific surface area.Both micropore and mesopore are the main contribution of storage space for shale gas.The organic carbon content,maturity (RO) of organic matter and mineral component content all influence pore development of the marine shale gas reservoirs.In general,the pore volume of shale increases with the increase of organic carbon content.The porosity of shale reduces as the vitrinite reflectance (RO) increases.The content of clays and brittle minerals in the organic-rich shale also has a certain influence on the development of shale pores.


Cite this article

ZHAO Pei,LI Xian-qing,TIAN Xing-wang,SU Gui-ping,ZHANG Ming-yang,GUO Man,DONG Ze-liang,SUN Meng-meng,WANG Fei-yu . Study on Micropore Structure Characteristics of Longmaxi FormationShale Gas Reservoirs in the Southern Sichuan Basin[J]. Natural Gas Geoscience, 2014 , 25(6) : 947 -956 . DOI: 10.11764/j.issn.1672-1926.2014.06.947

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