Palaeogene structural evolution of Dongying Depression,Bohai Bay Basin,NE China

Based on the new all-covering 3D seismic data and the drilling-logging data, we established the sequence stratigraphic framework for Dongying Depression and identified two kinds of structural systems in Palaeogene, i.e. the extensional structural system and the transtensional structural system. The extensional structural system consists of different normal faults that predominantly trend NE, EW, and NW. The attitudes of the normal faults vary in different tectonic settings. However, the transtensional structural system consists of some strike–slip faults and some normal faults. According to the analysis of the relationships between the faults and the sedimentary sequences of Dongying Depression, we considered that the extensional structural system was developed mainly from the Palaeocene to the middle Eocene, whereas the transtensional structural system was mostly developed from the middle Eocene to the Oligocene. In addition, we found that the structural systems had transformed since 43.5 Ma, when the subduction direction and activity rates of the Pacific Plate changed and the dextral strike–slip movement of the large-scale Tanlu fault zone started from eastern China. The extensional structural deformation was probably derived from the back-arc extension triggered by subduction rollback of the Pacific Plate under the Eurasian Plate, whereas the transtensional structural deformation was probably related to the regional dextral strike–slip movement induced by the subduction of the Pacific Plate and the continents’ collision between the Indian Plate and the Eurasian Plate.     

渤海湾盆地东营凹陷北带油包裹体成分特征

油包裹体成分在油源对比和流体包裹体PVT热动力学模拟具有至关重要的作用。本文采用常规荧光光谱、定量荧光技术和在线压碎群体包裹体成分分析方法对东营凹陷北带沙三段和沙四段砂岩储层样品中的油包裹体成分进行分析。荧光光谱分析结果表明油包裹体荧光颜色从黄色-黄白色-白色-蓝白色到蓝色呈现连续变化特征,主波长范围在445nm至550nm之间,指示了东营凹陷北带捕获的包裹体中油的成熟度从低到高呈连续变化。观察到的发蓝白色荧光的油包裹体荧光光谱主波长均小于500nm,黄色荧光的油包裹体荧光光谱主波长大于500nm。油包裹体荧光光谱参数主波长和Q值反映发蓝白色和黄色荧光的油包裹体中饱和烃、芳烃、非烃含量和API明显不同,发蓝白色荧光的油包裹体中的烃类具有密度相对较小、成熟度较高的特征。定量荧光和群体包裹体成分结果也表明由于发蓝白色和黄色荧光的油包裹体成分不同导致QGF光谱以及TSF参数都具有明显的区别,发蓝白色荧光的油包裹体甲烷含量偏高,而发黄色荧光的油包裹体C₇-C₉含量相对偏高。     

渤海湾盆地东营凹陷南坡东段孔二段烃源岩生排烃潜力分析

始新统孔店组是渤海湾盆地济阳坳陷东营凹陷油气勘探向深层转移的重要层系,受演化程度较高的制约,东营凹陷南坡东段孔二段（孔店组二段）烃源岩生排烃潜能存在争议,为探讨东营凹陷深层含油气系统,明确孔二段烃源岩生排烃潜能,笔者等从含油气检测结合烃源岩分析的角度进行讨论。通过孔二段沉积时期古地貌恢复,结合地震剖面,明确了孔二段沉积时期的古地貌,探讨了孔二段烃源岩发育的平面分布特征;通过地化及薄片观察,对孔二段烃源岩有机质丰度、类型和成熟度进行研究,且对高成熟孔二段烃源岩进行原始有机碳含量恢复,结合流体包裹体测试、冷阴极发光、荧光观察等系统分析,判识孔二段烃源岩生排烃潜能。研究认为,孔二段烃源岩展布范围较大,且在沉降中心发育较厚的孔二段烃源岩层;孔二段烃源岩原始有机碳含量较高,有机质来源以高等植物为主,属于Ⅱ1—Ⅲ型有机质,成熟度较高,烃源岩已进入生气阶段,综合评定为中等—较好烃源岩。孔店组主要发生两期油充注和一期天然气充注：第一期油充注发生在沙三段沉积时期;第二期油充注发生在东营组沉积时期;第三期天然气充注发生在平原组沉积时期,结合东营凹陷古近系烃源岩生排烃模拟结果,认为孔店组原油具有孔二段烃源岩的生排烃贡献。通过分析孔二段烃源岩发育特征结合生排烃研究,判识孔二段烃源岩生排烃潜能,为东营凹陷深部含油气系统研究鉴定基础。     

东营凹陷不同超压成因的有效应力特征

利用实测流体压力(DST)测试结果,结合声波和密度测井资料,对超压段所识别的不均衡压实作用和生烃作用两种超压成因机制下的实测压力和有效应力随深度的变化特征进行了分析,结果表明:①两种不同成因机制下的实测压力和有效应力特征具有明显的差异性,不均衡压实作用在压实过程中导致流体排出受阻,地层流体承担上覆岩层压力形成超压,表现为阻止了地层有效应力增大,因此其实测压力增大段和静岩压力增大趋势大体一致,而有效应力随深度基本保持不变;生油作用在地层正常压实之后形成超压,发育程度不受上覆岩层压力的影响,因此超压的增大在深度上与上覆岩层压力增大不具有一致性,且超压对有效应力的影响要小于不均衡压实作用;②这两种不同的超压成因使得有效应力的变化随着声波速度而出现加载和卸载两种趋势,从而可以用来判断超压成因,利用实测资料计算的有效应力结果说明东营凹陷超压成因机制包括不均衡压实作用和生油作用,但不均衡压实作用形成超压的范围和规模较小,生油作用对深部大规模超压和强超压的形成至关重要.     

Lithology and formation conditions of paleogene rocks in the Dongying Depression (Bohai Bay Basin,China)

The Dongying Depression is one of the largest depressions in terms of hydrocarbon reserves not only within the Bohai Basin, but also in the whole Pacific region. This is related to the inherited pattern of geological evolution, as well as the optimal combination of oil source rocks, reservoirs, and caprocks, which alternate in both lateral and vertical directions. Diversity of the lithofacies composition of Eocene and Oligocene sediments in thick (proluvial, deltaic, fan deltaic, and deep-water) hemipelagic and gravitational deposits in the composition of various fans, predetermined the wide distribution of sandstone and gritstone beds with good filtration-capacity properties. The beds were filled with hydrocarbons that migrated from the adjacent layers of oil shales and clays. The role of the principal reservoirs was played by sandstones, which were deposited in distributary channels of Eocene deep-water fans. The detailed study of these underwater fans will make it possible to expand the reserves of hydrocarbons explored now in the Dongying Basin.     

Origin of Oils in “Subtle pools” in the Dongying Depression, Bohai Bay Basin, China

Subtle traps or oil pools have become an important exploration play in the Dongying Depression, Bohai Bay Basin, east China. Despite recent successes in exploration, the formation mechanisms of subtle traps are still not well understood. The majority of subtle oil pools in the Dongying Depression are developed in the middle interval of the Es3 Member of the Paleogene Shahejie Formation with the subtle traps being primarily of lenticular basin-floor turbidite sands encompassed in mudstones. Oil in the subtle traps was previously thought to have migrated directly from the surrounding source rocks of the same formation （Es3）. Detailed geochemical investigation of 41 oils and 41 rock samples from the depression now indicates that the oils from the subtle traps cannot be correlated well with the surrounding Es3 source rocks, which are characterized by high Pr/ Ph （〉1）, low Gammacerane/C30hopane, representing a freshwater lacustrine setting. In contrast the oils features low Pr/Ph （〈1） and relatively high Gammacerane content, showing a genetic affinity with the underlying Es4 source rocks, which also have the same qualities, indicating a brackish lacustrine setting. Oils in the Es3 subtle traps are probably derived from mixed sources with the contribution from the upper Es4 source rocks predominating. Therefore unconventional oil migration and accumulation mechanisms need to be invoked to explain the pooling of oils from the ES4 source rocks, which probably came through a thick low interval of the Es3 source rocks with no apparent structural or stratigraphic pathways. We suggest that the subtle oil migration pathway probably plays an important role here. This finding may have significant implications for future exploration and the remaining resource evaluation in the Dongying Depression.     

东营凹陷王家岗孔店组油气成因解析

东营凹陷南斜坡东段王家岗地区孔店组原油特征明显不同于沙河街组为主的上部层系.孔店组原油具有高含蜡量、低含硫特征;多项生物标志物成熟度指标一致显示其成熟度高于上部层系,反映母源岩相对较高的成熟度.同区沙河街组原油具有相对低蜡、高硫、低熟-中等成熟等相反的特征,表明研究区内孔店组、沙河街组原油为不同成因原油.油-油、油源对比显示孔店组原油既有沙四段烃源岩的典型特征(如高含量伽玛蜡烷),也有沙四段烃源岩不具备而孔店组烃源岩具备的特征(如C29-规则甾烷优势).正构烷烃单体烃同位素δ13C值揭示孔店组原油与沙河街组原油有别,与深层孔店组烃源岩接近.综合研究认为,王家岗地区孔店组原油具有混源性,油气主要来自深层沙四段、孔二段烃源岩.研究区孔店组油气的发现及其与以往发现油气的不同表明深层另一套烃源岩的存在及广阔的深层油气勘探前景.     

Geological structure,history of development,and oil and gas bearing properties of the Dongying Depression (Basin of Bohai Bay)

The basin of Bohai Bay is formed by numerous large and small blocks of the earth’s crust submerged to different depths along large faults. Depressions occur along submerged limbs of the largest blocks, which are depocenters of sediment accumulation, mainly for deep water sediments. Eighty depressions are located in this territory, which measures 200000 km², and the Dongying Depression is one of the largest among them. During the Cenozoic age, the amplitude of submersion within the limits of this depression reached 6–9 km. Numerous deposits of oil and gas have been found in the sediments formed during this period, which are mainly gritstones, sandstones, clays, and pyroshales.     

王古1井奥陶系油气成因及其意义

首次在东营凹陷南斜坡王古1井奥陶系古潜山中获得深层高蜡油(含蜡量40．84％),其富含蜡质烃,甾、萜类等高分子量化合物含量甚微．采用分子筛络合技术对王古1井原油中的甾、萜类化合物进行了浓缩,并对碳酸盐岩储层中的方解石脉包裹体进行了化学成分分析．结果表明,王古1井奥陶系原油及储层包裹烃的组成与分布具有深层孔店组烃源岩的特征,与沙四段烃源岩相关性差,揭示奥陶系原油不同于以往发现的第三系沙河街组原油．正构烷烃单体同位素δ^13C值分析也表明,王古1井原油与孔店组烃源岩接近且变化趋势大体一致,反映孔店组为其可能的油源岩．王古1井奥陶系油气的发现表明东营凹陷存在一套迄今尚未发现的深层油源岩,该区具有深层油气勘探潜力．     

渤海湾盆地东营凹陷碎屑流主控型深水体系沉积过程及模式

【研究目的】碎屑流是深水环境沉积物搬运和分散的重要机制,其相关的砂岩储层是含油气盆地重要的勘探目标,然而,与经典浊流及浊积系统相比,对碎屑流主控型深水体系的发育规律目前仍知之甚少。【研究方法】本文基于岩心、测井及全三维地震资料,通过系统的岩心观察描述、测井及地震资料解释,对渤海湾盆地东营凹陷始新统沙三中亚段深水体系沉积过程及模式开展研究。【研究结果】结果表明,沙三中深水体系发育九种异地搬运岩相,可概括为四大成因类型,反映了块体及流体两种搬运过程。岩相定量统计表明,该深水体系主要由碎屑流沉积构成,浊流沉积很少,碎屑流中又以砂质碎屑流为主。重力流在搬运过程中经历了滑动、滑塌、砂质碎屑流、泥质碎屑流及浊流等5个阶段演变,发育5类主要的深水沉积单元,包括滑动体、滑塌体、碎屑流水道、碎屑流朵体及浊积薄层砂。从发育规模及储层物性上,砂质碎屑流水道、朵体及砂质滑动体构成了本区最重要的深水储层类型。【结论】认为沙三中时期充足的物源供给、三角洲前缘高沉积速率、断陷期频繁的断层活动以及较短的搬运距离是碎屑流主控型深水体系形成及演化的主控因素,最终基于沉积过程、沉积样式及盆地地貌特征综合建立了碎屑流主控型深水体系沉积模式。本研究将进一步丰富深水沉积理论,为陆相深水储层预测提供借鉴。     

渤海湾盆地东营凹陷牛庄洼陷岩性油气藏平面富集主控因素

随着油气勘探程度的加深,岩性油气藏的重要性日益显现,而查明油气富集规律是岩性油气藏勘探的关键。渤海湾盆地东营凹陷牛庄洼陷沙三中亚段发育大量岩性油气藏,文章以此为研究目标,着重分析其平面上油气分布的主要控制因素。研究结果表明,牛庄洼陷岩性油气藏的分布受控于洼陷内流体性质、断层作用和沉积相展布3种地质因素。它们对洼陷区岩性油气藏富集规律的影响分别在于：洼陷内流体运聚单元控制着油气在平面上的富集区,牛庄洼陷南北两侧汇聚流发育区是油气聚集的有利地带,而洼陷北部平行流和东西两侧发散流发育区不利于油气成藏;同生断层泵吸作用使得油气在牛庄洼陷平行流和发散流发育区可形成局部汇聚流,从而聚集成藏,断层的侧向遮挡作用则使得牛庄洼陷生成的油气多富集在靠近边界断层的洼陷内侧;物性较好的浊积水道微相最有利于油气的富集,朵叶体和水道间次之,外缘最差。     

东营凹陷原油单体烃碳同位素特征及其在油源识别中的应用

为揭示东营凹陷部分复杂成因油气的来源,对该区原油、烃源岩单体烃碳同位素进行精细特征分析与油源追踪。东营凹陷不同成因原油具有不同正构烷烃单体烃碳同位素特征。沙三段淡水成因原油碳同位素曲线分别以nC₁₅、nC₃₂为主峰,碳同位素总体偏重、前峰极其富集13C;沙四段咸水成因原油一般以nC₂₃为分界线,近似呈对称的双峰分布,δ¹³C值较沙三段成因原油的轻。沙三段、沙四段成因原油碳同位素分别与沙三段、沙四段烃源岩的聚类相关。牛庄洼陷沙三中段透镜体岩性油气藏原油单体烃碳同位素值介于沙三段、沙四段烃源岩之间,与沙四段烃源岩及相关原油具有更好的相关性,验证以往关于牛庄洼陷沙三中段隐蔽油气藏原油为沙三段、沙四段成因的混源油观点。东营凹陷南斜坡孔店组原油碳同位素总体相对较轻、近直线型分布,与孔店组烃源岩、黄骅坳陷孔店组成因原油的碳同位素曲线聚类相关,指示其与孔店组烃源岩具有成因联系。在正常油窗范围内,成熟度对东营凹陷烃源岩及相关原油碳同位素的影响较小,后者主要受控于母源与古沉积环境。单体烃碳同位素可以很好地应用于东营凹陷油气成因与油源研究,该方法是对以往生物标志物地球化学研究的补充与深化。     

Dynamic Systems of Petroleum Accumulation in the Nanpu Depression,Bohai Bay Basin,China

<正>It is significant to distinguish the dynamic systems of petroleum accumulation(DSPA) for the understanding of petroleum accumulation and distribution.According to the formation pressure framework,genetic types of petroleum and characteristics of conduit systems,three dynamic systems of petroleum accumulation were identified in the vertical profile in the Nanpu depression,Bohai Bay basin.The deeper DSPA(including formations Es_3 to Es_2) is a sealed system with high-overpressure and high-mature self-sourced oil.Most of the crude oil in the system accumulated in the periods of late Oligocene(23.5 Ma) and late Pliocene(2.4 Ma).The middle DSPA(including formations Es_1 to Ed_1) is an overpressured half-sealed system with mature or lower-mature self-sourced oil.The accumulation of oil in the system also occurred in the late Oligocene(23.5 Ma) and late Pliocene(2.4 Ma).The shallower DSPA(including formations Ed_2 to Q) is a hydrostatic system with lower-mature aliensourced oil from the middle system.Oil within this system accumulated only in the late Pliocene period.The oil in the shallower system migrated vertically along the faults from the formerly accumulated oil in the middle system by lateral migration along the sandbodies,whereas petroleum accumulation in the deeper system was mainly derived from the system itself by lateral migration along the sandbodies and rarely migrated out of the system.In this case,it seems that the deeper system is a more potential exploration prospect in addition to the other two proved favorable systems.     

Fluid Dynamic Field in Bozhong Depression, Bohai Bay Basin

The physical accumulation process of oil and gas, as thenatural nuids buried in the underground, follows the mechanism of fluid flow dynamics (Tao, 19831 Hubbert, 1953,1940). More and more lines of evidence show that the underground fluid dynamics not only controls hydrocarbon expulsionand accumulation directly, but also influences hydrocarbongeneration and preservation. Therefore, this research has beenpursued with great interests by worldwide petroleum geologists(GOng and Yang, 19993 Ye et…     

渤海湾盆地东营凹陷沙四下亚段地层压力演化与天然气成藏

通过实测压力、泥岩声波时差、流体包裹体古压力恢复,对东营凹陷民丰地区沙四下亚段地层压力的演化特征进行了分析。研究表明,民丰地区地层压力纵向上存在“常压-超压-常压”三段式结构;时间上,沙四下亚段地层压力具有“二旋回波动模式”,即存在“常压-弱超压-常压”和“常压-超高压-常压（弱超压）”的演化过程,其中两次地层超压的形成时间与中深层天然气藏的两期成藏时间相对应,为油气藏的形成提供了动力条件。研究区地层压力的动态演化过程是多因素作用的结果,第一次高压的形成是地层快速沉积产生欠压实的结果,生烃贡献相对较小;第二次超压的形成是烃源岩大量生烃和原油裂解成天然气造成的,沉积作用为辅。由于地温梯度降低、断裂-砂体泄压、饱和气藏深埋等作用的影响,现今民丰地区沙四下储层表现为以常压为主,伴生部分超压的分布特征。     

东营凹陷北部陡坡带稠油地球化学特征与成因

对东营凹陷北部陡坡带郑家—王庄地区稠油与相对稀油烃类组成进行了定性与定量分析。发现多数原油遭受不同程度的破坏 ,饱和烃、芳烃馏分呈有序缺失 ,于多数原油中检测到生物降解标志物 2 5 -降藿烷系列。地质与地球化学综合研究认为 ,以生物降解—氧化及相关的生化 /化学作用、以水洗—重力分异—轻质组分逸散为主的物理作用是郑家—王庄原油稠化的重要机理 ;东营凹陷北部“有限后退型”盆地边界发育的风化壳潜山、砂砾岩扇体储层孔渗条件好、油藏埋深浅、盖层条件差和不整合面等通道与外界的连通是郑家—王庄及邻区重质油形成的根本原因。提出生物标志物绝对定量可作为识别原油遭受次生改造作用程度、判断不同类型生物标志物抵抗降解能力大小的有效指标。利用生物标志物 ,发现郑家—王庄局部地区原油具有不同降解级别原油相混的混合现象 ,可能反映两次或多次充注。郑家—王庄及其邻区有望获得相对稀油新增储量。     

Delta-fed turbidites in a lacustrine rift basin: the Eocene Dongying depression,Bohai Bay Basin,East China

Sediment avalanche from delta ramp is one of the significant development mechanisms for a turbidite system in a lacustrine basin. To advance our understanding of deep-water sedimentary processes in a lacustrine delta ramp, delta-fed turbidites in the Eocene Dongying depression of the Bohai Bay Basin were studied using core data, 3-D seismic data and well log data. Sandy debris flows, muddy debris flows, mud flows, turbidity currents, slides, sandy slumps and muddy slumps were interpreted based on the identification of lithofacies. Data indicates that deep-water sedimentary processes in the study area were dominated by debris flows and slumps, which accounted for ～68% and 25% (in thickness) of total gravity flow deposits, respectively; turbidity-current deposits only accounted for ～5%. Mapping of turbidites showed that most were deposited after short-distance transportation (<20 km), restricted by the scale of deep-water areas and local topography. Channels, depositional lobes, debris flow tongues, muddy turbiditic sheets, slides and slumps were identified in a delta-fed ramp system. Slides and slumps were dominant at the base of slopes or at the hanging walls of growth faults with strong tectonic activity. Channels and depositional lobes developed in gentle, low-lying areas, where sediments were transported longer distances. Sand-rich sediment supply, short-distance transportation and local topography were crucial factors that controlled sedimentation of this ramp system. Channels generally lacked levees and only produced scattered sandstones because of possible hydroplaning of debris flow and unstable waterways. In addition to lobes, debris flow tongues could also be developed in front of channels. These findings have significant implications for hydrocarbon exploration of deep-water sandstone fed by deltas in a lacustrine basin.     

Characteristics of faults and their implications for oil and gas enrichment in the Liaoxi Depression,Bohai Bay Basin,eastern China

The faults that developed in the Liaoxi Depression can be classified into three types according to their extent and connectivity with the source and reservoir rocks (i.e. type I faults, type II faults and type III faults). These faults played different roles in controlling the basin geomorphology; the formation and evolution of the source rocks, reservoir rocks, cap rocks and traps; and the migration and accumulation of hydrocarbons in the Liaoxi Depression. Extending from the basement to the Neogene strata, type I faults, which are the largest in the basin, mainly controlled the development and basin-scale geomorphology; type II faults mainly controlled the sub-tectonic zones; and type III faults mainly controlled the formation and evolution of the traps. The movements of type I and type II faults during the hydrocarbon expulsion period were closely related to oil and gas migration. The rates of fault activity varied among the different sags of the Liaoxi Depression. Type I faults in both the northern and southern sags appear to have moved considerably during the hydrocarbon generation and expulsion stages, which strongly promoted hydrocarbon migration, whereas weakly active type I faults in the central sag made limited contributions to hydrocarbon migration. The sealing behaviour of the faults controlled the hydrocarbon migration directions and locations, and the good lateral sealing ability of the type I faults in the northern and southern sags confined the accumulation of hydrocarbons within the sags independently. However, the type I faults in the central sag partially opened laterally, which increased the likelihood of hydrocarbon migration from the sag centre to the uplift and reduced the likelihood of hydrocarbon accumulation within the sag centre. Therefore, the oil- and gas-enrichment patterns in the Liaoxi Depression are closely related to the characteristics of the faults, with traps near types I and II faults showing an increased likelihood of oil- and gas-field formation, as observed with the JZ9-3, LD4-2 and LD5-2 wells, and traps located in the sags remote from types I and II faults showing a reduced likelihood of oil and gas accumulation.     

渤海湾盆地冀中坳陷石油地质条件、资源潜力及勘探方向

渤海湾盆地冀中坳陷最主要的烃源层是古近系的沙三段、沙一段,新生古储和自生自储是发现储量最多、石油资源最丰富的2种成藏组合。近年来,冀中坳陷在富油洼槽区地层-岩性油藏、隐蔽型潜山油藏以及致密油领域勘探不断取得重要突破与发现,展现了良好的勘探前景。通过冀中坳陷常规与非常规油藏形成条件解剖,分析成藏主控因素,构建多类型油藏成藏模式并总结富集规律,完善建立不同类型油藏资源评价参数,优选评价方法,开展了新一轮资源潜力评价。结果表明:冀中坳陷常规石油地质资源量为24.4×108t,资源探明率为46%,致密油地质资源量为5.19×108t。由于剩余石油资源依然丰富,未来要持续深化富油洼槽区及斜坡带的构造-岩性及隐蔽型常规油藏勘探,稳步推进束鹿凹陷泥灰岩致密油勘探,加强致密油甜点区综合评价。     

渤海湾盆地东营凹陷示烃成岩作用及其演化特征*

富含有机酸的烃类流体在由泥质烃源岩进入储集层后将发生一系列的示烃成岩反应。研究发现有6类成岩现象与烃类活动密切相关,即酸性烃类流体的溶蚀作用、蒙脱石脱水与伊利石化、碳酸盐矿物的铁离子浸染、沥青—铁核的轨迹、自生高岭石的形成以及耗水、底积碳酸盐胶结层的隔层分布。这些特殊的成岩现象是含油气盆地内特有的标识,对指示油气初次侵入程度、运移的方向与轨迹、工业聚集度以及最终成藏场所的确定具有重要的参考价值。基于所发现的示烃成岩矿物而建立的“含油气盆地碎屑岩成岩演化规律”,对胜利油区复杂油气藏勘探起到了指导作用,也可为今后含油气区储集层的有效性确定提供借鉴。