渤中西洼东三段烃源岩特征与油气成藏模式
江涛;李慧勇;胡安文;王明春;赵书铮
【摘要】渤中西洼东营组烃源岩埋深较浅、成熟度相对较低,其生烃潜力一直未受重视.为了明确东营组烃源岩特征及其与油气成藏关系,对东营组烃源岩有机质丰度、类型、成熟度、油源对比及其对油气成藏的影响进行了一系列研究.结果认为:渤中
西洼东三段烃源岩有机质丰度高,在埋深大于3500m的东三段有机质成熟度Ro＞1.0％,达到了生油高峰,是渤中西洼重要的烃源层系.通过油源对比分析,认为东三段
烃源岩原油主要环绕渤中西洼主洼槽呈环带状分布.断层、砂体是渤中西洼东三段
烃源岩有效的输导体系要素,主要发育烃源岩-断层、烃源岩-砂体、烃源岩-砂体-断层复合接触型3种油气高效输导类型.根据烃源岩的发育特征,结合输导体系与烃源岩的配置关系研究,认为东三段主要为自生自储油气成藏模式.在渤中西洼的北部,东营组烃源岩可以作为浅层油气成藏的有效烃源岩,油气主要通过沟通东营组烃源岩
的大断裂垂向运移至浅层成藏,因而浅层油气具有较大的勘探潜力.东三段烃源岩生
排烃能力及油气成藏模式的重新认识,对该区深化勘探及目标区的优选有一定的指
导意义.%The source rocks in Dong3 Member of west Bozhong Sag is featured by shallow buried depth and relatively low maturity and the corresponding hydrocarbon generation potential has been neglected in
the past.The effects of organic matter abundance,type,maturity and oil-source are researched to characterize the source rocks in Dongying Member and identify their correlation with hydrocarbon
accunulation.Research demonstrates that the source rocks in west Bozhong Sag is featured by high organic matter abundance.The organic matter maturity (Ro) of source rocks with buried depth exceeding 3 500 m
is greater than 1.0％,which has reached oil generation peak and can be considered as an important source rock series.Oil-source comparison indicates that the oil within Dong3 Member source rocks mainly distributes in a zonal pattern around the main subsag of west Bozhong Sag.Fault and sandbody are considered as the effective pathway systems in the Dong3 Member source rocks of west Bozhong Sag.There are three efficient pathway patterns,including source rock-fault,source rock-sandbody and source rock-sandbody-fault with conpound eontaction.It is concluded that the Dong3 Member is self-generation and self-preservation pattern according to the characterization of source rocks and the configuration patterns between path system and source rocks.The source rocks of Dong3 Member in the northern part of west Bozhong Sag can be taken as effective source rocks for shallow hydrocarbon accumulation.The hydrocarbon mainly migrates from source rocks to shallow reservoirs vertically by large-scale faults,whieh results in a great exploration potential.The re-understanding of hydrocarbon generation,expulsion and accumulation pattern could provide certain guidance for the further exploration and target-area selection.
【期刊名称】《特种油气藏》
【年(卷),期】2017(024)006
【总页数】6页(P12-17)
【关键词】烃源岩;成藏模式;勘探潜力;东三段;渤中西洼
【作者】江涛;李慧勇;胡安文;王明春;赵书铮
【作者单位】中海石油(中国)有限公司天津分公司,天津300452;中海石油(中国)有限公司天津分公司,天津300452;中海石油(中国)有限公司天津分公司,天津300452;中海石油(中国)有限公司天津分公司,天津300452;中海石油(中国)有限公司天津分公司,天津300452
【正文语种】中文
【中图分类】TE122.1
烃源岩是形成大中型油气田的物质基础，优质烃源岩的确定，对揭示油气生成、运移、聚集及富集规律具有十分重要的意义。渤中西洼广泛发育沙三段、沙一段和东三段3套烃源层[1-5]，其中，沙三段、沙一段是主要的烃源层系，在勘探初期，
认为东营组烃源岩埋深浅、成熟度低，忽略了东营组烃源岩对围区油气成藏的贡献。渤中西洼发育多个洼槽，表现为洼隆相间，结构复杂，有关各洼槽烃源岩特征及其油气成藏模式尚不明确，尤其是东三段烃源岩。随着勘探的深入，在渤中西洼周边发现了典型的以东营组烃源岩贡献为主的油藏，东营组烃源岩的生油意义逐渐被重视，但针对东营组烃源岩及其与油气成藏关系研究成果较少。尽管渤中西洼东营组地层埋深相对较浅，但烃源岩厚度大，东营组烃源岩能否作为渤中西洼主要的烃源岩，将对下步勘探部署有重要影响。因此，在系统研究渤中西洼东三段烃源岩特征的基础上，探讨其成藏作用，以期为该区下一步勘探目标的优选提供指导。
渤中西洼位于渤海海域西部，为渤中凹陷向西北延伸部分。南北分别与沙垒田凸起和石臼坨凸起相邻。内部可划分出石南洼槽、沙北洼槽和渤中西洼主洼槽3个亚
二级构造单元(图1)。
地震资料和钻井揭示，渤中西洼新生界地层发育齐全，从下至上依次发育古近系沙
