琼东南盆地深水块体流构成及其沉积特征

为了深化对琼东南盆地深水区沉积体系的认识,基于琼东南盆地深水区2D和3D地震资料,发现琼东南盆地深水区发育大量的块体流沉积.通过对块体流沉积进行精细刻画,识别出一些典型的块体流沉积特征:滑移体、陆坡陡崖、搬运块体、残余块体、挤压脊、逆冲断层以及块体流顶部的滞留沉积等.陡倾陆坡上块体流以杂乱反射为特征,地层变形剧烈,而宽...     

琼东南盆地崖北凹陷构造特征及其对油气成藏的影响

在对崖北凹陷地震资料精细解释的基础上,重新认识了凹陷结构和断裂发育特征。研究认为,受5号断裂控制,崖北凹陷整体呈北断南超的构造格局,凹陷可划分为陡坡带、深洼带和缓坡带。2号断裂控制的陵水低凸起对崖北凹陷崖城组煤系烃源岩发育有重要影响。继承性发育的伸展构造是崖北凹陷的主要构造样式,断层型圈闭是该地区发育的主要圈闭类型。崖北凹陷南部、东南部低角度缓坡带圈闭落实,并发育有匹配的煤系烃源岩,是崖北凹陷的有利勘探区域。     

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。     

构造因素对半地堑盆地的层序充填的影响

运用平衡剖面分析和构造物理模拟实验方法研究了典型铲式正断层模型上盘盆地的发育过程．研究表明，铲式正断层的产状以及断层上盘的变形方式直接影响上盘盆地的形态和沉积层序结构．简单铲式正断层的上盘发育相对简单的半地堑盆地，复杂铲式（坡坪式）正断层的上盘则发育包含有内部次级背斜凸起和向斜凹陷的复式半地堑，而且半地堑盆地的宽度与拆离断层面深度成正比．在沉积物补偿充填的情况下，渐进伸展将使半地堑的宽度也保持不变，从而使半地堑构造斜坡上产生“视水退”的层序结构现象，并且使盆地中“垂向加积”的沉积层序演变为宏观上“侧向加积”的沉积层序．这种由构造因素对半地堑盆地的层序充填的影响在渤海湾盆地的部分老第三纪断陷中得到印证．     

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。     

南海琼东南盆地气态烃地球化学特征及天然气水合物资源远景预测

天然气水合物研究覆盖了地球物理学、地球化学和地质学等多门学科,其中勘查地球化学方法可以从海底介质中直接获得与天然气水合物有关的地球化学信息,圈定水合物异常区域。近些年来大量的研究工作和陆续发现的地球物理和地球化学证据显示,南海北部海域是我国勘查天然气水合物最有潜力的区域之一。依据广州海洋地质调查局2005年第4航次获得的南海琼东南盆地沉积物酸解烃测试结果和高异常段位同位素分析数据,探讨了琼东南盆地气态烃地球化学分布特征和异常成因。结合西沙海槽已有的勘探资料和水合物成藏地质条件,分析南海北部西沙海槽—琼东南地区与天然气水合物有关的地球化学异常特征,并对水合物成藏远景进行了预测。研究成果为南海北部天然气水合物勘探提供地球化学证据。     

琼东南盆地中央峡谷天然气成藏特征及其主控因素

基于地震、测井、岩芯、岩屑和天然气样品分析化验等资料,研究了中央峡谷天然气成藏特征,探讨了成藏主控因素与成藏模式。研究结果表明,晚中新世—早上新世沿琼东南盆地中央坳陷发育一条大型海底峡谷,称之为中央峡谷,峡谷内充填了多期相互叠置的浊积砂岩,平均孔隙度为15%~33%,渗透率为11×10-3~971.3×10-3μm2,为较好的储层;发育了岩性和构造-岩性复合两大类圈闭。峡谷的气源来自于崖城组的煤系地层,属于煤型气。烃源岩的有机质类型为Ⅱ2和Ⅲ型,以Ⅲ型为主;热演化程度处于成熟—高成熟阶段,晚中新世—上新世达到生烃高峰。琼东南盆地中央坳陷是一个高温高压的坳陷,实测地温梯度平均值高达4.2~4.6℃/100m,实测压力系数为1.20~2.15。在高温高压的环境下,盆地内孕育众多的底辟构造,而峡谷下伏的底辟构造与谷内相互叠置的复合砂体在空间上有效的配置构成了天然气垂向与侧向运移的输导体系,成为峡谷天然气成藏的关键因素。     

琼东南盆地松东凹陷断裂发育特征

松东凹陷位于琼东南盆地东北部,是受琼东南盆地6号断裂控制、总体呈南断北超的新生代凹陷。松东凹陷断裂复杂,理清断裂的发育特征有助于加深对琼东南盆地区域构造演化的认识,具有重要油气地质意义。基于近几年新采集的地震资料,结合区域地质背景,从剖面上和平面上多方位对松东凹陷的各种类型断层进行了系统解释和厘定,分析了断裂的组合样式、活动期次、发育规律及展布特征。结果表明:松东凹陷单条断层剖面上多呈犁式、平直式,多条断层组合常呈复合"Y"字形、羽状、帚状和网状;平面上单条断层多为弧形、直线形,多条断层组合常呈帚状、斜交式和平行式;松东凹陷断层按期次可划分为始新世NE向、渐新世近EW向和中新世NWW向三组,NE向断层控制松东凹陷的边界及其内部次级构造,渐新世近EW向断层和中新世NWW向断层组合形成六组断裂带成排分布,并伴有多条近SN向走滑断层发育;松东凹陷不同期次断裂的发育是区域应力场伸展方向随时间发生顺时针旋转的结果。结合松东凹陷的断裂发育特征和成因机制分析,最终认为该区断裂对油气成藏起到控烃源、控运移和控圈闭的作用,SN向走滑断层周缘以及构造变换带是油气成藏有利位置。     

琼东南盆地断陷期层序地层模式

琼东南盆地断陷期指示了从陆相向滨海环境演化的完整序列,因而断陷期层序的形成和演化既受幕式裂陷作用控制,又受区域海平面变化的影响。盆地断陷期代表一个巨层序(或构造层序),由3个层序组和6个层序组成,其中层序组分别对应于断陷期3次构造幕,层序则与全球三级海甲面旋回吻合。层序内部体系域特征与幕式构造作用的演化阶段有关,根据沉积环境差异可以划分为冲积平原型和滨海湖盆型两种层序模式。在裂陷作用阶段,幕式构造作用是断陷盆地内层序形成和演化的主导因素,区域海平面变化仅相对加强或减弱构造作用的影响;而在裂后热沉降作用阶段,随着构造沉降作用减弱,海平面变化影响更显著,其层序样式与陆表海环境的层序相似。     

Characteristics of Overpressure Systems and Their Significance in Hydrocarbon Accumulation in the Yinggehai and Qiongdongnan Basins, China

Overpressure systems are widely developed in the central depression and paleo-uplift in the Yinggehai and Qiongdongnan basins. They can be divided into three types according to the origin of abnormally high formation pressure in the reservoirs, i.e. the autochthonous, vertically-transmitted and laterally-transmitted types. The autochthonous overpressure system results from rapid disequilibrium sediment loading and compaction. In the allochthonous overpressure system, the increase of fluid pressure in sandstone originates from the invasion of overpressured fluid flowing vertically or laterally through the conduit units. The autochthonous overpressure system occurs in the deep-lying strata of Neogene age in the central depression of the Yinggehai and Qiongdongnan basins. The vertically transmitted overpressure system is developed in the shallow strata of Late Miocene and Pliocene ages in the diapiric zone of the central Yinggehai basin, and the laterally transmitted overpressure system occurs in the Oligo     

琼东南盆地陆坡体系发育特征及其控制因素

琼东南盆地位于南海北部大陆边缘,是发育于前古近系基底之上的裂陷盆地,自中新世以来进入裂后沉降期。10.5Ma以来,随着盆地演化进入加速沉降阶段,盆地水深迅速增大,陆坡体系开始发育。根据陆坡体系的外部形态及其内部沉积构成特征,在空间上自西向东可以将其划分为3段,盆地西部陆坡以快速进积的陆坡楔状体为主要特征;盆地中部陆坡以陡倾的陆坡角度,大量的陆坡峡谷、沟谷和大规模的沉积物重力流等陆坡沉积为特征;盆地东部陆坡以宽缓的陆坡形态为主要特征。研究表明,沉积物供给和断裂活动对陆坡体系的发育都具有重要的控制作用;同时,陆坡发育时期所经历的沉积过程、古地貌形态和相对海平面变化对陆坡体系的发育也具有一定的控制作用。     

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

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＹｉｎｇｇｅｈａｉａｎｄＱｉｏｎｇｄｏｎｇｎａｎｂａｓｉｎｓａｒｅｔｗｏｏｆｔｈｅｆｏｕｒｍａｊｏｒＴｅｒｔｉａｒｙｂａｓｉｎｓｄｅｖｅｌｏｐｅｄｉｎｔｈｅｎｏｒｔｈｅｒｎｃｏｎｔｉｎｅｎ－ｔａｌｓｈｅｌｆｏｆｔｈｅＳｏ...     

琼东南盆地现今地层温度分布特征及油气地质意义

温度状态是决定油气形成与保存的关键因素，精准的深部地层温度预测对盆地油气资源战略评价和勘探开发具有重要意义。琼东南盆地是我国当前深水油气资源勘探的重点区块，揭示盆地深部地层温度分布格局及主控因素是深水油气勘探研究的一项基础工作。结合钻孔实测温度和系统的岩石热物性参数，文章揭示了琼东南盆地现今深部地层温度分布特征。研究表明，琼东南盆地的优势储层温度为90~150℃ （数据占比>70%），高于国外学者提出的储层“黄金温度带”（60~120℃），推测与南海北部大陆边缘盆地高地热背景有关。此外，盆地T30—T70 界面处的估算温度均表现为“西高东低”的特征，高温区域位于西部的崖南凹陷；深部温度分布格局与地层的埋深、热导率结构以及因区域拉张程度不同引起的基底热流差异等诸因素有关。成果为琼东南深水油气勘探开发及钻井工艺设计提供了坚实的地热学依据。     

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.     

琼东南盆地现今地层温度分布特征及油气地质意义

温度状态是决定油气形成与保存的关键因素,精准的深部地层温度预测对盆地油气资源战略评价和勘探开发具有重要意义。琼东南盆地是我国当前深水油气资源勘探的重点区块,揭示盆地深部地层温度分布格局及主控因素是深水油气勘探研究的一项基础工作。结合钻孔实测温度和系统的岩石热物性参数,文章揭示了琼东南盆地现今深部地层温度分布特征。研究表明,琼东南盆地的优势储层温度为90~150℃ （数据占比>70%）,高于国外学者提出的储层“黄金温度带”（60~120℃）,推测与南海北部大陆边缘盆地高地热背景有关。此外,盆地T30—T70 界面处的估算温度均表现为“西高东低”的特征,高温区域位于西部的崖南凹陷;深部温度分布格局与地层的埋深、热导率结构以及因区域拉张程度不同引起的基底热流差异等诸因素有关。成果为琼东南深水油气勘探开发及钻井工艺设计提供了坚实的地热学依据。     

Features of Late Cenozoic Deepwater Sedimentation in Southern Qiongdongnan Basin,Northwestern South China Sea

Based on high resolution 2D and 3D seismic data acquired in recent years,using sequence stratigraphy analysis and geophysical methods,we discuss the features of Late Cenozoic deepwater sedimentation in the southern Qiongdongnan (琼东南) basin.The study area entered a bathyal slope environment in the Miocene.The channel developed in the Sanya (三亚) Formation was controlled by a fault break,and its shingled seismic characteristics represent multiple erosion and fill,which may indicate that turbidite current developed in the slope environment.The polygon faults found in mudstone of the Meishan (梅山) Formation represent the deepwater hungry sedimentary environment.The large-scale channels developed on the top of HuangUu (黄流) Formation could be the result of a big sea level drop and an increase of sediment supply.The fantastic turbidite channel developed in Late Quaternary in the slope environment has "fan-like" body and long frontal tiny avuision channel The analysis of these features suggests that the sediment supply of the study area in the post-rifting period was dominant from the Vietnam uplift in the southwest.These deepwater sedimentary features could be potential reservoirs or migration pathways for deepwater petroleum systems.     

琼东南盆地西南部新生代裂陷特征与岩浆活动机理

琼东南盆地是南海西北陆缘上一个北东走向的伸展裂陷带,向西与北西走向的莺歌海盆地相接,因此其西南部的构造演化包含了较多红河断裂走滑活动的信息。综合地质分析,我们发现琼东南盆地的发育既受控于南海北部陆缘的南东-南南东向伸展作用,又受到红河断裂左行走滑作用的控制和影响。盆地西南部裂陷带内发育了复式裂陷结构,由复式半地堑和复式地堑构成;裂陷带边缘的斜坡带和隆起上,以半地堑样式为主。始新世-早渐新世岩浆活动较多,主要表现为顺层充填的火山活动;中中新世后的岩浆活动分布较广,主要沿北西走向大断裂分布,在地震剖面上主要表现为尖锥状火山式活动特点。海盆扩张期,凹陷内缺乏岩浆活动。推测复式裂陷特点和较多的岩浆活动与陆坡区地幔上涌较高,具有较高的地温梯度,导致岩石圈弹性厚度降低有关。     

The deep mantle upwelling beneath the northwestern South China Sea:Insights from the time-varying residual subsidence in the Qiongdongnan Basin

Deep hot mantle upwelling is widely revealed around the Qiongdongnan Basin on the northwestern South China Sea margin.However,when and how it influenced the hyper-extended basin is unclear.To resolve these issues,a detailed analysis of the Cenozoic time-varying residual subsidence derived by subtracting the predicted subsidence from the backstripped subsidence was performed along a new seismic reflection line in the western Qiongdongnan Basin.For the first time,a method is proposed to cal-culate the time-varying strain rates constrained by the faults growth rates,on basis of which,the pre-dicted basement subsidence is obtained with a basin-and lithosphere-scale coupled finite extension model,and the backstripped subsidence is accurately recovered with a modified technique of backstrip-ping to eliminate the effects of later episodes of rifting on earlier sediment thickness.Results show no residual subsidence in 45-28.4 Ma.But after 28.4 Ma,negative residual subsidence occurred,reached and remained ca.-1000 m during 23-11.6 Ma,and reduced dramatically after 11.6 Ma.In the syn-rift period(45-23 Ma),the residual subsidence is ca.-1000 m,however in the post-rift period(23-0 Ma),it is positive of ca.300 to 1300 m increasing southeastwards.These results suggest that the syn-rift sub-sidence deficit commenced at 28.4 Ma,while the post-rift excess subsidence occurred after 11.6 Ma.Combined with previous studies,it is inferred that the opposite residual subsidence in the syn-and post-rift periods with similar large wavelengths(＞102 km)and km-scale amplitudes are the results of transient dynamic topography induced by deep mantle upwelling beneath the central QDNB,which started to influence the basin at ca.28.4 Ma,continued into the Middle Miocene,and decayed at ca.11.6 Ma.The initial mantle upwelling with significant dynamic uplift had precipitated considerable con-tinental extension and faulting in the Late Oligocene(28.4-23 Ma).After ca.11.6 Ma,strong mantle upwelling probably occurred beneath the Leizhou-Hainan area to form vast basaltic lava flow.