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大港油田上古生界煤系烃源岩地球化学特征与二次成烃

大港油田上古生界煤系烃源岩地球化学特征与二次成烃

第38卷 第6期

OIL&GASGEOLOGY2017年12月 收稿日期:2016-12-26;修订日期:2017-10-11。

第一作者简介:周立宏(1968—),男,教授级高级工程师,油气综合勘探。E-mail:zhoulh@prtrochina.com.cn。 基金项目:中国石油重大科技专项(2014E-06-01)。文章编号:0253-9985(2017)06-1043-09doi:10.11743/ogg20170604大港油田上古生界煤系烃源岩地球化学特征与二次成烃

周立宏,滑双君,孙超囡,代 昆,牟智全

(中国石油大港油田分公司,天津300280)

摘要:大港油田上古生界煤系地层主要分布于中南部,分布面积近10000km2

。烃源岩包括煤层、碳质泥岩和泥岩3种类型,总厚度100~450m,纵向上主要分布在太原组和山西组,本溪组少量发育。煤层有机质丰度高,85%以上属于好-极好烃源岩类型,而泥岩丰度各地区之间差异较大。烃源岩显微组分构成中以镜质组含量占优势,50%以上,成熟阶段具有良好的生气条件,同时受成煤环境的影响,主要成煤中心的煤系地层也富含一定的富氢组分,在低熟-成熟阶段具有良好的生油能力。上古生界在地史演化中经历了多期构造活动的改造,煤系源岩也随之经历了两次生烃过程,其中二次生烃范围分布广,资源规模大,是潜山勘探的重要区域。按照构造演化分类,油田内发育4种埋藏史类型,即早埋晚抬型、早抬晚埋型、持续深埋型与稳定埋藏型。除早埋晚抬型之外,其他3类均具有二次生烃条件。经多年的勘探,在二次生烃范围内,相继在孔西“古生中储型”和乌马营潜山、埕海潜山、王官屯潜山“古生古储型”原生油气藏实现了潜山勘探的重大突破。

关键词:二次生烃;煤系烃源岩;原生油气藏;大港油田

中图分类号:TE122.1 文献标识码:AGeochemicalcharacteristicsandsecondaryhydrocarbongenerationofcoal-measuresourcerocksinUpperPaleozoicofDagangoilfield

ZhouLihong,HuaShuangjun,SunChaonan,DaiKun,MuZhiquan

(DagangOilfieldCompany,PetroChina,Tianjin300280,China)

Abstract:Coal-measureformationsintheUpperPaleozoicmainlydistributesincentral-southpartofDagangOilfieldand

coversanareaofnearly10000km2.Sourcerocksthereconsistofcoalbeds,carbonaceousmudstoneandmudrock,andhaveagrossthicknessof100to450m.Vertically,theydistributemainlyintheTaiyuanandShanxiFormationswithsomedevelopedintheBenxiFormation.Thecoalbedsarerichinorganicmatter(morethan85%)andarehightoveryhighqualitysourcerocks,whiletheorganicmattercontentinmudstonevariesgreatlyfromplacetoplace.Vitrinitedominatesthemaceralofthesourcerockswithacontentofmorethan50%,indicatingfavorableconditionsforgasgenerationduringthematurestageoftherocks.Meanwhile,affectedbycoal-formingenvironment,thecoal-measurestratainthemaincoal-formingcentersarealsocontainsomehydrogen-richmacerals,hintinglargeoilgenerationcapacityduringlowmaturitytomaturestage.TheUpperPaleozoicstrataexperiencedmultiplephasesoftectonicactivities,sowerethecoal-measuresourcerocks,whichwentthroughtwostagesofhydrocarbongeneration.Thesecondaryhydrocarbongenerationwascha-racterizedbylargeareaandhighresourcepotentialandhasbeenthefocusofstudyduringtheburiedhillexploration.Fourtypesofburialhistorycanberecognizedintheoilfieldbasedonthetectonicevolution:theearly-burialandlate-lifttype,theearly-liftandlate-burialtype,thecontinuousdeep-burialtypeandthesteady-burialtype.Exceptforthefirsttype,alltheotherthreetypespossessedfavorableconditionsforsecondaryhydrocarbongeneration.Yearsofexplorationintheareaofsecondaryhydrocarbongenerationyieldedprimaryoilandgasdiscoveriesinburiedhillsoneafteranother:Kongxi,Wumaying,ChenghaiandWangguantun,tonamejustafew.Keywords:secondaryoilgeneration,coal-measuresourcerock,primaryoilandgasaccumulation,DagangOilfield

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