南海西北次海盆深水扇系统沉积演化特征

基于高品质二维地震资料的分析解释,在南海西北次海盆深海平原区识别出大规模深水扇系统。深水扇系统上扇为限制性水道复合体发育区,中扇为多期扇体垂向叠置区,下扇则以水道-朵体沉积为主。琼东南中央峡谷-水道是本区深水扇系统的主要物源通道,沉积物主要来源于红河、北部陆架-陆坡以及中西沙隆起区。本区深水扇系统可基本划分为晚中新世（Ⅰ）、中新世（Ⅱ和Ⅲ）以及第四纪（Ⅳ和Ⅴ）五期。各期深水扇的空间展布受到先存地形和物源供给强度的控制,双峰海山将深水扇系统分隔为南北两部分,早期沉积的扇体改变了后期扇体沉积地形。在丰富物源供给下,水道的冲溢频率较高,各个深水扇之间存在明显的侧向上叠迁移特征。沉积物源和南海北部“三段式”陆坡地形控制着整个南海北部深水扇系统的发育和演化。     

琼东南盆地深水区构造格局和幕式演化过程

基于大量琼东南盆地深水区高精度的地质-地球物理和钻井资料解释, 确立了该盆地"南北分带, 东西分块"的基本构造格局; 通过构造-地层、沉降史和沉降中心厘定等方面的综合研究, 在琼东南深水盆地中深入描述和分析了T70重要的构造变革界面特征, 该界面之下发育了一系列分散的、NE向展布的小型断陷盆地群, 该界面之上一直到T60界面发育时期, 盆地的沉降中心逐渐迁移到位于琼东南盆地中央坳陷区的、呈NE-WE-NWW弧形展布的大型断坳式盆地内, 该断坳盆地与下伏小型断陷盆地群构成显著的叠加关系; 以控盆边界断层的性质和几何学分布, 确定下伏的NE向展布的小型断陷盆地群受控于NW-SE向拉伸应力场, 而上覆的断坳盆地由近SN向拉伸应力作用所形成; 区域对比表明该界面广泛分布于南海北部大陆边缘盆地中, 具有区域性分布的特征; 生物地层和区域对比表明该界面年龄为32 Ma, 与南海初始扩张的年龄一致.因此, 该界面是一个发育于南海北部的、代表了南海扩张开始的一个区域性构造变革界面.该界面的发育导致了琼东南盆地深水区盆地结构和构造演化的复杂性, 以该界面为基础, 结合盆地充填序列中的其他重要界面和盆地的沉降史分析, 将盆地的构造演化划分为断陷、断坳、裂后热沉降和加速沉降4个构造演化幕, 从而确定了该盆地具有典型的幕式演化特征; 详细讨论了盆地周缘板块运动学重组事件和岩石圈深部活动对琼东南盆地幕式发育过程的控制机制.      

琼东南盆地古近纪幕式裂陷及构造、层序和沉积的综合响应过程

通过对区域性角度不整合、构造沉降阶段性演化以及断裂幕式活动和古构造格架变化等信息的识别与厘定,揭示了琼东南盆地古近纪构造活动的幕式演化过程及其特征。进一步结合层序地层与沉积充填综合分析,系统论述了幕式裂陷作用对沉积层序形成与演化的控制。研究表明：琼东南盆地古近纪经历了3个裂陷阶段,即裂陷Ⅰ幕（S₁₀₀-S₈₀）、裂陷Ⅱ幕（S₈₀-S₇₀）和裂陷Ⅲ幕（S₇₀-S₆₀）,分别对应盆地的初始断陷期、主断陷期和断坳转换期。裂陷活动早期以强烈的差异性块断作用为主导,而晚期逐渐被区域性坳陷作用和少量断裂活动共同控制的均一化沉降作用所取代,整体呈现出弱-强-弱的演化特征。裂陷作用的幕式过程及不同裂陷幕同沉积构造活动的差异性通过对可容纳空间、沉降速率、同沉积断裂活动和古构造格架的深刻影响,进而控制了盆地内层序地层单元与沉积旋回的整体发育、沉积与沉降中心的时空展布以及层序地层格架下沉积体系域的构成样式。     

Filling History and Post-Breakup Acceleration of Sedimentation in Baiyun Sag,Deepwater Northern South China Sea

The Baiyun (白云) sag in the southern Pearl River Mouth basin is the largest and deepest sag in deepwater northern South China Sea.Researches and exploration in this sag have revealed many distinct features of the sag.This article reports its filling history through backstripping of depth data of interpreted sequence boundaries.Maps of sediment rates of 10 sequences from 49 Ma to the present were constructed,showing the spatio-temporal variation of the sediment rate.Three stages of sediment infilling,49-17.5 Ma,17.5-10.5 Ma,and 10.5-0 Mn,were divided by abrupt changes of sedimentary patterns.If the breakup of the South China Sea took place at ～30 Mn,significant pint-breakup acceleration of sedimentation was observed at 17.5-15.5 Ma and 13.8-12.5 Mn,indicating acceleration of subsidence at these times.We propose that the onset of strong post-breakup snbsidence at ～17.5 Ma was an important tectonic event that changed the pattern of sedimentation from discrete and medium-rate depmition centers in both main and south snbsags to restricted but high-rate deposition in the main snbsag.The cause and implications of this newly recognized event need tobe investigated.     

Gravity Flow on Slope and Abyssal Systems in the Qiongdongnan Basin, Northern South China Sea

The study of new seismic data permits the identification of sediment gravity flows in terms of internal architecture and the distribution on shelf and abyssal setting in the Qiongdongnan Basin (QDNB). Six gravity flow types are recognized: (1) turbidite channels with a truncational basal and concordant overburden relationship along the shelf edge and slope, comprising laterally-shifting and vertically-aggrading channel complexes; (2) slides with a spoon-shaped morphology slip steps on the shelf-break and generated from the deformation of poorly-consolidated and high water content sediments; (3) slumps are limited on the shelf slope, triggered either by an anomalous slope gradient or by fault activity; (4) turbidite sheet complexes (TSC) were ascribed to the basin-floor fan and slope fan origin, occasionally feeding the deep marine deposits by turbidity currents; (5) sediment waves occurring in the lower slope-basin floor, and covering an area of approximately 400?km2, were generated beneath currents flowing across the sea bed; and (6) the central canyon in the deep water area represents an exceptive type of gravity flow composed of an association of debris flow, turbidite channels, and TSC. It presents planar multisegment and vertical multiphase characteristics. Turbidite associated with good petrophysical property in the canyon could be treated as a potential exploration target in the QDNB.     

Characteristics and Origin of Yacheng Gas Field in Qiongdongnan Basin, South China Sea

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＹｉｎｇｇｅｈａｉａｎｄＱｉｏｎｇｄｏｎｇｎａｎｂａｓｉｎｓａｒｅｔｗｏｏｆｔｈｅｆｏｕｒｍａｊｏｒＴｅｒｔｉａｒｙｂａｓｉｎｓｄｅｖｅｌｏｐｅｄｉｎｔｈｅｎｏｒｔｈｅｒｎｃｏｎｔｉｎｅｎ－ｔａｌｓｈｅｌｆｏｆｔｈｅＳｏ...     

南海北部陆坡白云深水区深水沉积结构要素

在回顾深水沉积结构要素研究的基础上,结合白云深水区的勘探实践,对白云深水区深水沉积的结构要素进行了研究。将白云深水区深水沉积划分为4种结构要素,分别为水道、天然堤-溢岸沉积、席状砂和块体搬运沉积。水道是白云深水区深水沉积的主要组成部分,也是重要的储层;水道按成因可分为侵蚀型、侵蚀/加积型和加积型;水道充填沉积物的岩性变化较大,有砾岩、砂岩、泥岩以及几种岩性的混合。天然堤-溢岸沉积主要以泥岩、粉砂岩为主,平面上,天然堤-溢岸沉积与水道走向平行,横向上远离水道扩散,侧向连续性好但垂向连续性差。席状砂位于水道末端,具有朵叶状外形,分为层状和合并状2种类型：层状席状砂具有相对低的砂岩体积分数,泥岩和砂岩互层;而合并状席状砂岩体积分数高,砂层和砂层接触,夹有少量的泥。块体搬运沉积包括滑塌、滑块、块体流、碎屑流、坡身失稳复合体、块体搬运复合体等;块体搬运沉积常直接位于层序界面上,对下伏地层侵蚀明显,分布广泛,可作为良好的油气封盖层。     

南海北部大陆架莺琼盆地新生代海平面变化

南海北部大陆架莺琼盆地是建立西太平洋新生代海平面变化的关键地区之一。基于有孔虫和钙质超微化石资料所建立的莺歌海盆地和琼东南盆地新生代相对分辨率较高的年代地层格架,通过南海海域表层建立的浮游有孔虫含量与水深的定量关系,辅以古生态、成因相及特征沉积构造分析和反射地震剖面的海岸上超分析,编制了海平面变化曲线。识别出包含三个完整二级海平面变化旋回和半周期的海平面上升旋回。海平面变化幅度在0～200 m之间。海水最深的时期在早中新世晚期至中中新世早期以及上新世早期,与Haq曲线较为吻合。     

Petroleum System in Deepwater Basins of the Northern South China Sea

The northern South China Sea margin has experienced a rifting stage and a post-rifting stage during the Cenozoic.In the rifting stage,the margin received lacustrine and shallow marine facies sediments.In the post-rifting thermal subsidence,the margin accumulated shallow marine facies and hemipelagic deposits,and the decpwater basins formed.Petroleum systems of deepwater setting have been imaged from seismic data and drill wells.Two kinds of source rocks including Paleogene lacustrine black shale and Oligocene-Early Miocene mudstone were developed in the deepwater basin of the South China Sea.The deepwater reservoirs are characterized by the deep sea channel fill,mass flow complexes and drowned reef carbonate platform.Profitable capping rocks on the top are mudstoues with huge thickness in the post-rifting stage.Meanwhile,the faults developed during the rifting stage provide a migration path favournble for the formation of reservoirs.The analysis of seismic and drilling data suggests that the joint structural and stratigraphic traps could form giant hydrocarbon fields and hydrocarbon reservoirs including syn-rifting graben subaqueous delta,decpwater submarine fan sandstone and reef carbonate reservoirs.     

南海北部深水西区石油地质特征及勘探前景

南海北部深水西区是一个前瞻性的油气勘探新领域,包括神狐隆起西南端、永乐隆起及琼东南盆地中央坳陷带大部分区域,属于南海北部被动人陆边缘的一部分,构造演化上经历了裂陷和裂后两大阶段。本次研究通过对南海北部深水西区及邻区大量地震和钻井资料研究认为,该区不仅具有优越的基本石油地质条件,而且具有有利的成藏条件,其特点为：①三套烃源岩、五大富牛烃凹陷,资源潜力巨大;②陵三段扇三角洲或滨海砂岩与陵二段海侵泥岩储盖组、三亚、梅山滨浅海相砂岩或低位扇砂体与浅海-半深海相泥岩储盖组合、黄流组低位扇砂体与半深海相泥岩付盖组合、梅山组台地边缘礁灰岩与莺黄组深海相泥岩的储盖组合等4套储盖组合;③构造、低他体和礁圈闭成群成带发育;①各种垂向和侧向运移通延发育齐全,存在超压-常压突变模式、超压-常压过渡模式和强超压区的构造与岩性圈闭成藏模式。南海北部深水西区具有与国外获得巨大成功的深水勘探地区类似的石油地质条件,因此,勘探前景良好,资源潜力巨大。但是深水勘探是一个高风险、高技术、高投入的领域,应当“由浅及深,循序渐进”地推动该区深水勘探。     

南海北部陆坡深水曲流水道的识别及成因

深水水道是深水沉积体系中重要的组成单元,其作为潜在的油气储集体也被油气行业所关注。深水水道多处于深水环境下的沉积地层中,因此对于其直接的观测和研究都比较困难。基于近年新采集的多道2 D和3 D地震资料,利用相干时间切片、RMS均方根振幅、3D振幅可视化等地球物理手段对南海北部陆坡深水水道进行了识别和研究。该水道为更新世深水曲流水道,与来自中南半岛的浊流侵蚀有关,水道呈SW—NE向展布,侧向侵蚀特征明显。3D振幅可视化图显示该水道轴部为强振幅反射,推测为富砂充填,其余部分为弱振幅反射,推测为富泥充填,这点与世界已钻水道特征一致。深水曲流水道的形成过程和内部结构复杂,其内部砂体与泥岩常互层出现,泥岩的封堵作用会阻碍流体的流动或形成超压,同时也可起到良好的盖层作用,因此对于深水曲流水道的勘探和开发要重视这个问题。      

中国南海礼乐盆地新生代断裂体系的发育与演化

断裂体系发育特征是礼乐盆地新生代构造演化的重要表现形式。运用研究区丰富的二维地震资料,在详细刻画主干断裂和次级断裂的几何学特征基础上,厘定了断裂体系各时期的活动规律,明确了断裂体系演化的时空差异性：古新世-早渐新世断裂体系以NNE向和NEE向主干断裂为主,早期整体断裂活动速率低且NNE向断裂占主导,后期NNE和NEE向断裂活动均大幅增强;晚渐新世-早中新世断裂体系表现为NNE和NEE向主干断裂继承性活动、NW向主干断裂和NEE-近EW向次级断裂形成;中中新世以来断裂体系活动微弱、消亡。响应于太平洋板块、欧亚板块和印澳板块交汇碰撞、古南海消亡以及新南海扩张的区域地质背景,礼乐盆地的新生代演化过程可分为陆缘裂陷(包括陆缘初始裂陷和陆缘强烈裂陷)、漂移裂陷及前陆拗陷三个阶段;古新世至早中新世拉张应力场由NWWSEE到SN向的顺时针转变和中中新世以来拗陷背景下来自东、南侧的挤压控制了礼乐盆地断裂体系的发育与演化。     

Thermodynamic Modeling of Fluid-Bearing Natural Gas Inclusions for Geothermometer and Geobarometer of Overpressured Environments in Qiongdongnan Basin, South China Sea

It is a very difficult problem to directly determine fluid pressure during hydrocarbon migration and accumulation in sedimentary basins. pVt modeling of coupling hydrocarbon fluid inclusion of its coeval aqueous fluid inclusion provides a powerful tool for establishing the relationship of formation pressure evolution with time. Homogenization temperature of fluid inclusion can routinely be measured under microthermometric microscopy. Crushing technique has been employed to obtain the composition of fluid inclusions, and the commercial software VTFLINC easily and rapidly completes the construction of p-t phase diagram. The minimum trapping pressure of hydrocarbon fluid inclusion would be then determined in the p-t space. In this paper, three samples of YC21-1-1 and YC21-1-4 wells at YC21-1 structural closure, Qiongdongnan basin, South China Sea, were selected for the pVt modeling practice, and the formation pressure coefficient (equals to fluid pressure/hydrostatic pressure) changing trend with time has primarily been established. The modeling results also indicate that the reservoirs of Lingshui and Yacheng formations in YC21-1 structure are within a very high potential system and would have undergone a discharging of thermal fluids through top seal rupture, which depicts that there is a very high risk for natural gas exploration in this area.     

琼东南盆地断裂活动性定量计算及其发育演化模式

在地震剖面解释的基础上,运用断层活动速率法和位移-距离法对琼东南盆地主要断裂系统的活动性进行了定量计 算。结果表明,断裂的活动性与盆地的演化阶段相对应,同时可以在同裂陷阶段划分出始新世-早渐新世裂陷幕和晚渐新 世断坳转换幕,这两幕裂陷控制了盆地深部的基本构造格局。单条断层在早渐新世至晚渐新世期间断裂主要活动中心存在 由东向西迁移的过程,盆地断裂系统活动中心在晚渐新世至早中新世也存在由东向西迁移的过程,盆地内规模较大的复合 断裂带具有区段式活动的特征。将盆地内断裂系统发育模式总结为两种：以6号和11号断裂带为代表的简单生长模型,断裂 系统发育演化过程中表现为单一区段断层独立生长的特征,断层简单地由中间向两侧生长,断层位移距离曲线自始至终为 半椭圆型,且最大位移大致位于断层中部;以2号和5号断裂带为代表的生长连通型生长模式,断裂带由多条区段式活动的 断层生长连接形成,其生长发育过程表现为沿断层面纵向上最大滑移量由各个区段的中心向各个区段交汇处迁移,由此各 个区段断端破裂扩展,最终相互连接而形成一条大型断裂带。     

南海北部琼东南盆地岩石热物性特征

岩石热物性是盆地模拟和预测深部温度时不可或缺的参数。琼东南盆地是当前我国海洋油气资源勘探开发的重点区 块，揭示该盆地的热状态和烃源岩热演化历史均离不开真实可靠的岩石热物性参数。前人虽然对南海北部地区的岩石热物 性开展过相关研究，仍存在实测数据偏少、代表性不足和相互矛盾等问题，亟需新增一批新的实测数据来弥补该区基础地 热参数的不足。文章对采自琼东南盆地19口钻孔的32块岩心样品开展了热导率、生热率以及密度和孔隙度等物性参数测 试，揭示了它们的空间展布特征、相互关系及其主控因素，建立了琼东南盆地新生界地层平均热导率和生热率，据此估算 出盆地沉积物的放射性生热贡献约占地表热流的33%。这些实测的岩石热物性参数为南海北部海域沉积盆地的盆地模拟和 地热相关研究提供了坚实的基础数据。     

The tectonic evolution of the Qiongdongnan Basin in the northern margin of the South China Sea

Qiongdongnan Basin is a Cenozoic rift basin located on the northern passive continental margin of the South China Sea. Due to a lack of geologic observations, its evolution was not clear in the past. However, recently acquired 2-D seismic reflection data provide an opportunity to investigate its tectonic evolution. It shows that the Qiongdongnan Basin comprises a main rift zone which is 50–100 km wide and more than 400 km long. The main rift zone is arcuate in map view and its orientation changes from ENE–WSW in the west to nearly E–W in the east. It can be divided into three major segments. The generally linear fault trace shown by many border faults in map view implies that the eastern and middle segments were controlled by faults reactivated from NE to ENE trending and nearly E–W trending pre-existing fabrics, respectively. The western segment was controlled by a left-lateral strike-slip fault. The fault patterns shown by the central and eastern segments indicate that the extension direction for the opening of the rift basin was dominantly NW–SE. A semi-quantitative analysis of the fault cut-offs identifies three stages of rifting evolution: (1) 40.4–33.9 Ma, sparsely distributed NE-trending faults formed mainly in the western and the central part of the study area; (2) 33.9–28.4 Ma, the main rift zone formed and the area influenced by faulting was extended into the eastern part of the study area and (3) 28.4–20.4 Ma, the subsidence area was further enlarged but mainly extended into the flanking area of the main rift zone. In addition, Estimates of extensional strain along NW–SE-trending seismic profiles, which cross the main rift zone, vary between 15 and 39 km, which are generally comparable to the sinistral displacement on the Red River Fault Zone offshore, implying that this fault zone, in terms of sinistral motion, terminated at a location near the southern end of the Yinggehai Basin. Finally, these observations let us to favour a hybrid model for the opening of the South China Sea and probably the Qiongdongnan Basin.     

南海北部琼东南盆地岩石热物性特征

岩石热物性是盆地模拟和预测深部温度时不可或缺的参数。琼东南盆地是当前我国海洋油气资源勘探开发的重点区 块,揭示该盆地的热状态和烃源岩热演化历史均离不开真实可靠的岩石热物性参数。前人虽然对南海北部地区的岩石热物 性开展过相关研究,仍存在实测数据偏少、代表性不足和相互矛盾等问题,亟需新增一批新的实测数据来弥补该区基础地 热参数的不足。文章对采自琼东南盆地19口钻孔的32块岩心样品开展了热导率、生热率以及密度和孔隙度等物性参数测 试,揭示了它们的空间展布特征、相互关系及其主控因素,建立了琼东南盆地新生界地层平均热导率和生热率,据此估算 出盆地沉积物的放射性生热贡献约占地表热流的33%。这些实测的岩石热物性参数为南海北部海域沉积盆地的盆地模拟和 地热相关研究提供了坚实的基础数据。     

南海南部深水多次波模拟分析与压制处理

南海南部陆缘构造复杂多变,海底崎岖不平,造成该区多道地震资料多次波十分发育且混杂复杂绕射波。为了识别深层有效反射信息、压制多次波,首先通过正演模拟分析深水条件下多次波的传播规律和特征,然后对复杂理论Pluto模型进行详细处理并试验了几种典型多次波压制方法,寻找到一套有效的多次波压制处理思路:通过表面相关多次波衰减(SRME)法降低多次波能量级别,运用τ-p域预测反褶积压制周期规律的近中道多次波,再在此基础上灵活运用高分辨率抛物线Radon变换对共反射点道集(CRP)进行中远道多次波压制。理论模型和礼乐盆地海区的实际资料处理结果表明,该方法能够较大程度上压制深水资料多次波并增强对深部有效信息的识别。     

南海北部古俯冲带的位置及其对南海扩张的控制

为了确定南海北部古俯冲带的具体位置,作者利用美国LCT综合反演软件对收集到的重磁数据进行处理解释,结果显示在南海北部从台湾西南部到一统暗沙隆起,即沿南海海盆北部陆坡为一条布格重力异常水平梯度峰值带,指示了古俯冲带的具体位置;其北部的高磁异常代表了与之对应的古火山弧。深反射地震资料也验证了南海北部陆坡位置存在古俯冲带,钻井资料显示俯冲带存在的时代为晚侏罗世到早白垩世。据此绘制了南海地区晚中生代到现今的构造古地理演化图,指出南海的扩张应与晚中生代俯冲带这个先存的软弱带有关,南海海盆正是从古俯冲带的位置开始扩张。