川东南奥陶一志留纪之交全频斑脱岩特征及页岩气指示意义

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Characteristics of Full-frequency Bentonite of Ordovician-Silurian Transition in Southeastern Sichuan and Its Significance Indicator of Shale Gas

LI 1，2， SHAN Chang'an1，2*，LIANG Xing³， GU Xiaomin³， HE Fangyu³， SHI Hailong³

1.SchoolofEarthSciencesandEngineering，Xi'aniyouUniversity，Xi'an，Shaani7oo65，China 2.ShaanxiKeyLaboatoryofetroleumccumulationGeologyXi'nouUiversityXianaani，a 3. Zhejiang OilfieldCompany，PetroChina，Hangzhou， Zhejiang31iioo，China

Abstract： Intheshaleofthe Wufeng-LongmaxiFormationin thesoutheasten SichuanBasin，thereareseveralsetsofbentonite beds，which keeps records of key information about numerous geological events.In order toclarify the characteristics of bentonitedevelopmentanditssgniicanceforshalegas，oreobservation，thinsectionientification，SEMobservation，whole rockX-raydifractionhavebeencariedoutforthecoreofseveralshalegasevaluationexplorationwelsandtypicalsections in neighboring areasinsoutheasteSichuan，andthefolowingresultshavebeenobtained.1）Inthestandard wellofbentonite in southeasternSichuanProvine，59bentonitelayersareidentified，andwerefurthrdividedinto6setsofbentonitedevelopment segments.2）In the processof volcanic ash deposition，thealkaline water environment chemically destroys the hard protein structure ofgraptolite，resulting in thephenomenonthat graptolite does notdevelop in the surrounding rocks above and below the bentonite.3）There are alteration phenomenain the bentonite，andtheproductsare mostly pyrite.4）Low-frequency andhigh-intensitydevelopmentofbentoniteoftenindicatehighqualityshale，andhigh-frequencyandhigh-intensityig frequencyand low-intensitydevelopment of bentonite often indicatesubprime-qualityshale，whilelow frequency and low intensity development of bentonite is regarded as ordinary organic shale.

Keywords： southeasterm Sichuan Basin; Wufeng-Longmaxi Formation; bentonite; alterationoccurs;significance for shale gas

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引言

四川盆地在奥陶—志留纪之交沉积了一套富有机质（总有机碳含量大于 2.00% 的五峰组一龙马溪组暗色页岩，是中国海相页岩商业性开发的重要层位。（剩余31434字）