丽水-椒江凹陷月桂峰组湖相烃源岩的主控因素与分布预测

月桂峰组是丽水-椒江凹陷的主力烃源岩层系。丽水-椒江凹陷在月桂峰组沉积时期为强断陷期,构造分割性强,沉积环境相对封闭,内部多个次洼的湖相烃源岩发育特征不清。为明确丽水-椒江凹陷内各富烃次洼中月桂峰组烃源岩发育条件及空间展布规律,进一步指导该区的油气勘探,利用钻井、岩芯、地球物理、地球化学及古生物等资料,基于湖盆演化动态全生命周期过程,提出“早期断层活动速率、中期母岩性质和遮挡条件、晚期火山活动”联合控制丽水-椒江凹陷4个次洼优质烃源岩的发育。在地质认识约束下,基于多属性神经网络深度学习,对中-深湖相烃源岩的空间展布进行了定量刻画。结合优质烃源岩的发育机制和中-深湖相烃源岩分布范围,对4个主要次洼内烃源岩的发育情况进行综合评价。结果表明,椒江A洼为Ⅰ类富烃次洼,丽水A洼和丽水C洼为Ⅱ类次富烃次洼,丽水B洼为Ⅲ类生烃次洼。     

海相烃源岩发育的古海洋模式及对南海北部的指示意义

通过汇总全球几个主要的优质海相烃源岩的古海洋-古气候特征以及相应的沉积环境,从有机质的生产、来源和保存条件3个维度将海相烃源岩发育的古海洋模式概括为:①三角洲-陆源海相模式,如西非陆缘盆地发育的烃源岩;②强蒸发-上升流模式,如墨西哥湾中生界烃源岩;③滞留静海-湿润气候模式,如北海盆地钦莫里阶烃源岩。结合现有资料分析认为,南海北部深水区恩平-珠海组(始新统—渐新统)处于半封闭局限海环境,普遍发育三角洲沉积体系,陆源有机质供应充足,气候条件适宜,具备发育优质海相烃源岩的古海洋条件。     

低勘探海域中建南盆地烃源岩早期预测

烃源岩是油气生成的物质基础。利用最新采集的高品质二维地震资料和综合研究成果,在中建南盆地内划分出4套地震层序,识别了5个不整合地震反射界面。通过分析盆地沉积演化特征,推测中建南盆地发育3套烃源岩,分别为中始新统湖相烃源岩、上始新统—渐新统湖相和海陆交互相烃源岩以及下—中中新统海相烃源岩。通过对其周边盆地进行类比分析,厘定了3套烃源岩的地震相特征;对不同沉积相带泥岩百分含量进行赋值,最终判识推测了中建南盆地新生代3套烃源岩泥岩厚度及分布特征。本研究可为盆地下一步油气资源评价、有利二级构造带分析和勘探部署提供参考。     

珠江口盆地惠州凹陷恩平组源岩特征及勘探潜力

惠州凹陷是珠江口盆地已经证实的富生烃凹陷,存在文昌组和恩平组两套有效烃源岩,一直以来都是以文昌组中深湖相烃源岩为勘探重点。随着勘探的深入,惠州地区以恩平组为代表的浅湖-沼泽相烃源岩的贡献越来越明显,惠州凹陷东部新区基本都为浅湖-沼泽相烃源岩供烃,周边井钻探证实该套烃源岩已经成藏。通过构造-结构剖析、物源分析、地震相调研对比、沉积体系细致研究以及对浅湖-沼泽相烃源岩的特征分析,揭示了惠东地区浅湖-沼泽相烃源岩优势发育机理。经过计算,惠东新区浅湖-沼泽相烃源岩资源量为8.6亿t,占到惠东地区总资源量的3/4,具有较大的勘探潜力。在总结惠东新区浅湖-沼泽相烃源岩特征的基础上优选出惠东新区浅湖-沼泽相烃源岩最有利勘探区带。本次研究摆脱了惠州凹陷单一烃源岩勘探束缚,推动了新区勘探进程。     

南海西部深水区崖城组煤系烃源岩的识别方法

琼东南盆地古近系崖城组海陆过渡相煤系烃源岩已被证实是该盆地的主要气源岩,但由于崖城组煤层具有层数多、单层薄、横向变化快的特点,而难以被识别和预测,尤其是勘探程度较低的深水区.本文利用综合种地质与地球物理法对煤系烃源岩进行更加准确的预测.首先,煤层可通过“三高,三低,一扩”的测井响应特征识别,而炭质泥岩可通过“四高,一低”的特征识别.基于该测井逻辑判断,煤系地层可通过测井曲线的聚类分析进行垂向的自动识别.在井震标的的约束下,煤层组可通过地震数据的“负相位,高吸收因子,低波阻抗和低频”等综合特征进行横向识别.然而,地球物理方法识别的煤系烃源岩分布范围不一定符合成煤的地质规律,因此本文从构造、层序和沉积的角度研究了煤系发育的主控因素约束其分布范围:①古地形及构造沉降控制了海陆过渡相煤系烃源岩在凹陷中的平面发育部位;②相对海平面变化通过控制可容空间变化以及海岸线迁移,从而控制烃源岩的发育规模以及垂向分布——具体的说,可容纳空间的增长速率和泥炭堆积速率的关系是控制煤层形成的最根本因素,在其平衡位置,煤层发育最厚、延伸最大;③原地碎屑的供应和沉积场所与古物源的距离,是制约高丰度烃源岩发育的关键因素,即距离古隆起海岸较近的沉积环境中陆源有机质较为丰富,便可形成高丰度煤系烃源岩.通过上述地质与地球物理联合识别方法,提高了煤系烃源岩发育的预测精度和可信度,为南海西部深水区的早期勘探提供了重要的参考依据.     

北部湾盆地海中凹陷流二段沉积体系及沉积模式

北部湾盆地北部涠西南凹陷多口钻井已获得高产油气流系列突破，其主力烃源岩层系为始新统流沙港组二段（流二段），但紧邻南侧的海中凹陷目前暂无商业油气发现。流二段既发育有深湖-半深湖相的烃源岩，同时在主力烃源岩段也发育有湖底扇储层，因此，研究海中凹陷潜在生烃层系（烃源岩、湖底扇储层）沉积体系发育规律对今后勘探开发具有指导意义。以高精度三维地震资料及测井资料为基础，通过岩芯相、测井相、地震相、地震属性的综合分析，探讨流二段沉积体系发育规律，建立沉积模式。研究表明：流二段主要发育滨浅湖、深湖-半深湖、湖底扇及辫状河三角洲4种沉积体系类型；在北陡南缓的半地堑构造样式控制下，北部陡坡带及洼槽带发育深湖-半深湖相，同时接受北部、东部2个物源方向的供源，分别在西洼、东洼发育湖底扇相，南部缓坡带发育滨浅湖及辫状河三角洲相。海中凹陷流二段好烃源岩主要发育在初始湖泛面层序位置（ts），湖底扇主要发育在湖泊扩张体系域内（TST），反映了在断陷湖盆背景下，构造沉降因素控制烃源岩发育程度强于湖平面变化因素。研究可为半地堑型断陷湖盆深湖-半深湖相烃源岩与湖底扇储层发育层序位置及共生模式的建立提供参考。     

南大西洋两岸盆地海相烃源岩特征与控制因素

南大西洋两岸盆地漂移期层系油气资源十分丰富,通过对两岸重点盆地漂移期主力烃源岩发育层位、生烃潜力、识别特征和分布范围对比分析,明确两岸发育早、晚两套主力海相烃源岩。其中,晚期的赛诺曼-土仑阶海相烃源岩分布范围较广。整体上,两岸北段和赤道段盆地漂移期主力烃源岩地化指标优于中段和南段盆地,西非一侧海域盆地烃源岩地化指标优于南美一侧盆地。在对重点钻井的矿物元素化验分析、沉积相和古地理分析基础之上,总结了局限海湾的古地理背景和沉积相带类型控制优质海相烃源岩发育程度和分布范围的规律,并进一步指出南大西洋两岸北段和赤道段盆地漂移期成熟生烃灶平面分布范围内的深水沉积砂体是主要有利勘探方向,以找油为主,中段含盐盆地内紧邻盐微盆的漂移期深水沉积砂体勘探潜力次之。     

渤海海域渤东地区烃源特征及资源潜力

为了客观评价渤东地区的油气资源潜力,利用钻井和地震资料,在地层、构造和沉积研究基础上,结合岩样与油样的有机地化分析,对该区烃源岩特征、油气来源、优质烃源岩分布、烃源岩热演化特征进行了系统分析,并在此基础上用盆地模拟法对该区资源潜力进行了预测。研究认为,渤东地区发育4套烃源岩,其中沙三段和沙一段烃源岩达到优质级别,沙四段和东三段烃源岩为中等-好级别;渤东地区已发现原油来源具有多样性,但总体上以沙三段来源原油为主;在渤东地区4套烃源岩中,沙三段优质烃源岩分布广、厚度大、热演化程度高,生烃潜力占总生烃量的74.8%,是该区主力烃源岩;在该区的4个洼陷中,渤东西洼生烃强度最大,庙西北洼其次,这2个洼陷是潜在富烃洼陷。     

南黄海盆地南五凹阜宁组“广湖咸水”烃源岩及其油气勘探意义

通过对南五凹钻井所揭示的阜宁组进行岩性、地球化学、古生物及地震相等综合分析证实,南五凹阜宁组发育中深湖相泥质烃源岩,且该套烃源岩形成于"广湖咸水"沉积环境。"广湖"即湖盆分布广泛,中深湖相泥质烃源岩在凹陷深洼处和缓坡带均有发育,平面上面积大,纵向上厚度大,具备生成油气的物质基础。"咸水"即烃源岩形成时期湖盆受到了海侵影响,致使水体性质偏咸。南五凹与中国东部古新世—始新世期间曾遭受海侵影响的其他湖盆类似,其形成的咸化烃源岩具有"排烃早"的特征。南五凹阜宁组湖相烃源岩"广湖咸水"沉积特征对于油气勘探具有重要意义。     

渤海海域庙西北洼烃源岩特征与勘探潜力

利用最新的三维地震、钻井、测井、烃源岩和原油分析化验等资料,对庙西北洼烃源岩地球化学指标、分布特征及成因环境进行了分析,借助盆地模拟和油源对比结果,明确了庙西北洼的主力烃源岩层系和勘探潜力。研究认为:庙西北洼发育东营组和沙一二段2套烃源岩,其中沙一二段烃源岩有机质类型好、丰度高、有机质成熟度高,为好—很好烃源岩,其排烃量占洼陷总排烃量的56%,是庙西北洼的主力烃源岩。油源对比结果表明,PL15-2亿吨级大油田的原油来自沙一二段烃源岩,进一步佐证了沙一二段为主力烃源岩,也预示了庙西北洼具有良好的勘探潜力。     

The effect of river-delta system on the formation of the source rocks in the Baiyun Sag,Pearl River Mouth Basin

Source rock formation influenced by river-delta system, especially in continental margin basins, is still poorly understood. This article aimed to reveal the effect of river-delta system on the formation of the source rock by taking the Baiyun Sag of the Pearl River Mouth Basin for example. Paleo-Pearl River began to develop since the Enping Formation, providing abundant organic matter beneficial for the formation of the source rocks in the Baiyun Sag. The main controlling factor of source rock formation in the Baiyun Sag is terrestrial organic matter supply rather than the paleoproductivity or redox conditions. Low Al/Ti and P/Ti ratios suggest low marine productivity, which may be associated with a large number of terrigenous detritus input, occupying about 43.04%–94.91%. There is a positive correlation between the oleanane/C₃₀hopane ratio and the TOC value, showing that terrigenous organic matter controls the source rock formation. The size of the delta below Pearl River estuary determines the extent of terrestrial organic matter supply. Source rocks with high organic matter abundance mainly formed in delta environment, and those in neritic environment in Enping and Zhuhai Formations also have high TOC values as a result of adequate terrestrial organic matter supply.     

Geochemistry and zircon U-Pb ages of the Oligocene sediments in the Baiyun Sag,Zhujiang River Mouth Basin

In this study, element geochemistry and zircon chronology are used to analyze the Oligocene sediments in the Baiyun Sag, Zhujiang River Mouth Basin. The experimental results are discussed with respect to weathering conditions, parent rock lithologies, and provenances. The chemical index of alteration and the chemical index of weathering values of mudstone samples from the lower Oligocene Enping Formation indicate that clastic particles in the study area underwent moderate weathering. Mudstone samples exhibit relatively enriched light rare earth elements and depleted heavy rare earth elements, "V"-shaped negative Eu anomalies, and negligible Ce anomalies. The rare earth element distribution curves are obviously right-inclined, with shapes and contents similar to those of post-Archean Australian shale and upper continental crust, indicating that the samples originated from acid rocks in the upper crust. The Hf-La/Th and La/Sc-Co/Th diagrams show this same origin for the sediments in the study area. For the samples from the upper Enping deltas, the overall age spectrum shows four major age peaks ca. 59–68 Ma, 98–136 Ma, 153–168 Ma and 239–260 Ma. For the Zhuhai Formation samples,the overall age spectrum shows three major age peaks ca. 149 Ma, 252 Ma and 380 Ma. The detrital zircon shapes and U-Pb ages reveal that during Oligocene sedimentation, the sediments on the northwestern margin of the Baiyun Sag were supplied jointly from two provenances: Precambrian-Paleozoic metamorphic rocks in the extrabasinal South China fold zone and Mesozoic volcanic rocks in the intrabasinal Panyu Low Uplift, and the former supply became stronger through time. Thus, the provenance of the Oligocene deltas experienced a transition from an early proximal intrabasinal source to a late distal extrabasinal source.     

Dissolution mechanism of a deep-buried sandstone reservoir in a deep water area: A case study from Baiyun Sag,Zhujiang River (Pearl River) Mouth Basin

Dissolution mechanism and favorable reservoir distribution prediction are the key problems restricting oil and gas exploration in deep-buried layers. In this paper, the Enping Formation and Zhuhai Formation in Baiyun Sag of South China Sea was taken as a target. Based on the thin section, scanning electron microscopy, X-ray diffraction, porosity/permeability measurement, and mercury injection, influencing factors of dissolution were examined, and a dissolution model was established. Further, high-quality reservoirs were predicted temporally and spatially. The results show that dissolved pores constituted the main space of the Paleogene sandstone reservoir. Dissolution primarily occurred in the coarse- and medium-grained sandstones in the subaerial and subaqueous distributary channels, while dissolution was limited in fine-grained sandstones and inequigranular sandstones. The main dissolved minerals were feldspar, tuffaceous matrix, and diagenetic cement. Kaolinization of feldspar and illitization of kaolinite are the main dissolution pathways, but they occur at various depths and temperatures with different geothermal gradients. Dissolution is controlled by four factors, in terms of depositional facies, source rock evolution, overpressure, and fault activities, which co-acted at the period of 23.8–13.8 Ma, and resulted into strong dissolution. Additionally, based on these factors, high-quality reservoirs of the Enping and Zhuhai formations are predicted in the northern slope, southwestern step zone, and Liuhua uplift in the Baiyun Sag.     

Three-dimensional facies architecture analysis using sequence stratigraphy and seismic sedimentology: Example from the Paleogene Dongying Formation in the BZ3-1 block of the Bozhong Sag,Bohai Bay Basin,China

The Bohai Bay Basin is a classic non-marine rift basin in eastern China. The Paleogene Dongying sequences are the main hydrocarbon-bearing stratigraphic unit in the basin. Using three-dimensional (3-D) seismic data and one well control in the BZ3-1 Block in the western slope of the Bozhong Sag, we analyzed 3-D facies architectures of the Dongying sequences. The Dongying Formation, a second-order sequence, can be subdivided into four third-order sequences (from base to top: SQ1, SQ2, SQ3, and SQ4). The facies architecture was analyzed by using the seismic sedimentology approach based on 3-D seismic data. Sediment of the Dongying sequences was derived from the northern Shijiutuo Uplift via four major configurations of incised valleys, namely “V”, “U”, “W”, and composite shaped incised valleys. Seismic stratal slices reveal branching and converging characteristics of the channels from upstream to downstream. On the basis of an integrated analysis of well log, core data, seismic facies based on multi-seismic attributes, three sedimentary facies (e.g., “delta”, “fan-delta”, and “shore” or “shallow lacustrine” facies) have been recognized. The four types of incised valleys and their evolution control the sedimentary systems in the sedimentation area. The numbers and sizes of the fans are controlled by the sedimentary systems at various scales. Incised valley-fill and deltaic sand bodies are excellent hydrocarbon reservoirs and potentially good exploration targets for the study area. The reservoir quality of sequences SQ1, SQ2, and SQ3 become better gradually from base to top. The proposed sediment dispersal patterns may aid in the prediction of potential reservoir distribution. This study also demonstrates that facies architecture analysis using sequence stratigraphy and seismic sedimentology may serve as an effective approach for constructing 3D facies models for petroleum exploration in areas lacking of well or outcrop data.     

东海陆架盆地瓯江凹陷古近系层序地层学与沉积特征研究

应用层序地层学方法,通过钻井、测井、地震反射等标志,识别出层序界面和最大海泛面,将东海陆架盆地瓯江凹陷古近系划分为3个层序,层序界面分别为T20、T40、T42、T50,并以地层叠置样式、岩性、岩相的变化为依据在单井上将每个三级层序细分为低位、湖侵和高位3个体系域;在层序格架内利用钻井和古生物资料分析了沉积体系在瓯江凹陷的平面展布：月桂峰组主要是三角洲相和湖泊相沉积,灵峰组和明月峰组是三角洲相和滨海相沉积,瓯江组和温州组为三角洲相和滨海相沉积,其中瓯江凹陷东次凹为浅海相沉积;沉积物源主要以西向东注入和西北方向向东南注入,同时揭示了古近系两次大规模海侵分别是古新世中期灵峰组沉积时期和始新世中期瓯江组沉积时期。     

珠江口盆地中部珠海组—珠江组层序结构及沉积特征

南海北部珠江口盆地珠海组分为SQ32、SQ25.5两个三级层序,珠江组划分为SQ23.8、SQ21、SQ17.5和SQ16.5四个三级层序,其中前3个层序分为水进域、高位域,后3个层序分为低位域、水进域和高位域。珠江组初期的白云运动使珠海组的浅水陆架环境变更为珠江组的陆架-陆坡沉积环境,造就了古地貌的更迭、层序界面的形成和沉积相的突变。层序界面在陆架主要为粗粒沉积物形成的侵蚀界面、浅水暴露界面,而陆坡为下切水道、丘状扇体底部侵蚀界面和滑塌层。层序的更迭使古珠江三角洲物源供给强度呈现强-弱-强-弱的特点,即珠海组时期的三角洲为陆架三角洲,沉积规模大;之后珠江组物源变弱,珠江组各层序低位域形成陆架边缘三角洲,水进域、高位域演化为陆架三角洲。低位期的三角洲前缘带越过坡折带沉积,并与陆架外的峡谷水道相连,三角洲进积、加积的碎屑沉积物向上陆坡内的白云凹陷内沉积,形成深水扇。因此,相对海平面变化、构造升降和沉积物供给强度控制着层序结构和沉积体展布。     

珠江口盆地文昌A凹陷油气差异分布特征

在烃源岩分布特征、有机质丰度、类型和成熟度分析的基础上,运用含油气盆地数值模拟技术,定量恢复了烃源岩热成熟演化史,探讨了油气差异分布特征。研究表明,文昌A凹陷各层系烃源岩分布广,厚度大,有机质丰度高;有机质类型文昌组偏Ⅱ1型,恩平组偏Ⅲ型,二者现今多处于高成熟—过成熟阶段。凹陷内烃源岩成熟时间早(文昌组约45.5Ma),现今成熟度高,以干气生成为主;凹陷边缘烃源岩成熟时间较晚(文昌组约30.0Ma),现今成熟度相对较低,以石油生成为主。凹陷现今油气差异分布的格局受制于有机质类型差异和热演化史不同,且下一步油气勘探方向,凹陷内以天然气为主,凹陷边缘以石油为主。     

珠江口盆地白云凹陷陆坡区10.5 Ma以来的沉积体系

通过对珠江口盆地白云凹陷陆坡区10.5Ma以来的地震相分析,共识别出席状平行亚平行地震相、透镜状前积地震相、深切河谷地震相、帚状地震相和杂乱地震相,不同的地震相分别代表不同的沉积体系类型。综合所识别的地震相类型,分析了陆架边缘下切谷、浊积扇和陆架边缘三角洲3种主要的沉积体系及其配置关系。物源供给是影响陆坡区沉积体系发育的最重要因素,是沉积体系发育的物质基础,海平面变化和构造运动为沉积体系发育提供了可容纳空间,3种影响因素共同影响了陆坡区沉积体系的发育。     

渤中凹陷西斜坡BZ3-8区块东营组东二下高分辨率井震层序及地震沉积学

渤海海域凹陷由于资料的限制,其沉积相研究多为宏观的区域性研究,制约了储层的精细解释。基于最新采集的高精度地震三维资料,结合地震地层学、层序地层学、地震沉积学等理论方法,开展渤中凹陷西斜坡BZ3-8区块东营组重点目的层,东二下层序高分辨率井震层序分析及其地震沉积学研究。结果表明,研究区南北两侧具有不同的物源体系和沉积相模式。低水位体系域(LST)和高水位体系域(HST)时期,研究区北部物源均形成扇形、朵形的地震多属性及振幅切片异常,对应于扇三角洲沉积;南部物源均形成NE向展布的条带状地震多属性及振幅切片异常,对应于辫状河三角洲沉积。海进体系域(TST)时期,湖平面快速上升导致扇体不发育,仅在研究区北部局部发育小规模的扇三角洲沉积。东二下层序LST(富砂)-TST(富泥)-HST(富砂)的岩相演化规律,充分反映了经典层序地层学理论层序格架中的地层岩相组合分布规律,对储层和烃源岩的预测具有指示意义。