Geological characteristics and main controls on enrichment and high yield of shale gas in Wufeng Formation-Long 11 submember,Luzhou area,Sichuan Basin
In recent years,high yield has been acquired from the Upper Ordovician Wufeng Formation-the first submem-ber of first member of the Lower Silurian Longmaxi Formation(Long 11 submember)in shale gas wells,Luzhou area,reveal-ing promising prospects in shale gas exploration and development.So,taking the organic-rich shales of Wufeng Formation-Long 11 submember in this area as examples,we discussed the extension of minor layers and microfacies together with the quality difference of shale reservoirs with different microfacies in an effort to better promote both efficient exploration and fine development in Luzhou area.And then,the predominant microfacies and the main controls on shale gas enrich-ment and high yield were made clear.Results show that,(i)Wufeng Formation-Long 11 submember can be subdivided in-to Wufeng Formation,Long 111,Long 112,Long 113 and Long 114,which individually represent their own characteristics in li-thology,electric property and fossil;(ii)totally,there developed 9 microfacies from Wufeng Formation to Long 11 submem-ber,among which,strongly reduced argillaceous siliceous shelf,strongly reduced silty siliceous shelf,and strongly reduced silty calcareous-siliceous shelf function as the most dominant microfacies,where shale features four highs in TOC,porosi-ty,gas content and brittleness.And it is mainly developed in Long 111,Long 112 and Long 113;and(iii)the strongly restrict-ed setting of deepwaters is the foundation for the extension of quality shale with high yield,abnormal pressure and rich gas content as the guarantee,and effective fracturing as the key,respectively.
Sichuan BasinLuzhou areaWufeng Formation—Long 11 submemberShale gasGeological characteristicsMain Control on enrichment and high yield
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