琼东南盆地深水区主要构造因素与成盆机制分析-地震解释与物理模拟实验

Located at the northwest continental slope of the South China Sea, the Qiongdongnan Basin bears valley-shaped bathymetry deepening toward east. It is separated from the Yinggehai Basin through NW-trend...     

国内外深水区油气勘探新进展

深水区油气资源丰富，近年来深水油气勘探不断升温。在全球6大洲18个深水盆地中已发现约580亿桶油当量的油气资源。目前，巴西、美国墨西哥湾的深水油气田已经投入生产，而且产量不断增加，西非地区也已进入开发阶段，西北欧、地中海以及亚太地区的许多国家也都在积极开展深水油气勘探或开发。海上油气钻探不断向深水区和超深水区发展，探井数目也在继续增加，投资力度不断加强，储量每年也有很大的增长。深水油气勘探成功率平均达到30％，其中，西非的勘探成功率最高。深水区烃源岩生烃潜力较好，最好的烃源岩主要分布于侏罗系、白垩系和第三系的地层中，储层以浊积岩储层为主，盖层通常比较发育，大多数圈闭都与地层因素有关。我国南海北部陆坡深水区盆地属准被动边缘盆地，从烃源岩、储层、盖层、圈闭到运聚条件等都具备了形成大型油气田的基本地质条件，具有丰富的资源前景。     

Physical oceanographic conditions in the deepwater Gulf of Mexico in summer 2000–2002

The circulation and distribution of water properties in the water column of the Gulf of Mexico influence the flux of carbon to the benthic environment. The eddy field of the upper 1000 m creates environmental conditions that are favorable for biological productivity in an otherwise oligotrophic subtropical ocean. This eddy field results in the transport of nutrients and organic matter into the photic zone through cross-margin flow of shelf waters, upwelling in cyclones, and uplift from the interaction of anticyclones with bathymetry. These conditions then allow the productivity that becomes a possible source of carbon to the benthos.Data from four cruises during summers of 2000–2002 are used to describe the currents and water property distributions in the deepwater Gulf of Mexico, which consists of water depths greater than 400 m. Comparisons are made to historical data sets to provide an understanding of the persistence of the characteristics of the Gulf and the processes that occur there.The currents in the Gulf are surface intensified, have minimum in 800–1000 m depths, and also exhibit bottom intensification, especially near sloping topography. Historical time series records show current speeds near-bottom reach 50–100 cm s⁻¹. At basin scales, these currents tend to flow cyclonically (counter-clockwise) along the bathymetry. These near-bottom, episodic, high-speed currents provide a mechanism for the transport of organic material, in both large and small particle sizes, from one benthic area to another.The distributions of temperature, salinity, nutrients, and dissolved oxygen during the study appear to be unchanged from historical findings. The source waters for the deep Gulf are the water masses brought into the Gulf by the Loop Current system. The properties in the upper 100–200 m are the most variable of the water column, consistent with their proximity to wind mixing, river discharge mixing, and atmospheric influences. Below 1500 m, there are no major horizontal variations in these water properties.     

海盆沉积“源-汇”系统分析:南海北部珠江海谷-西北次海盆第四纪深水浊积扇

运用近年来采集的高分辨率地震资料和多波束测深数据,在珠江海谷及西北次海盆深海平原区发现大规模发育的第四纪重力流沉积体系,该沉积体系沿珠江海谷以北西-南南东方向贯穿整个北部陆坡,进入西北次海盆后呈扇形展开,形成珠江海谷-西北次海盆大型深水浊积扇系统。据沉积体系空间展布特征差异,将珠江海谷划分为北、中、南三段,北段为过路侵蚀和水道下切,中段以水道充填和天然堤沉积为主,南段以水道-天然堤和朵叶体沉积共存为特征,揭示出北部陆坡珠江海谷是珠江口外陆缘物质输送海盆深海平原的主要通道;海盆区总体以朵叶体发育为特色,呈扇形展布。深水扇系统可分为三期次沉积体,其区域结构记录了重力流沉积物从侵蚀、卸载到南海海盆作为限制性盆地接收陆源沉积物的全过程,为“源-渠-汇”的研究构建了一个完美的范例。本文以珠江海谷-西北次海盆第四纪深水浊积扇沉积体系为例,完整地揭示了水道-扇体的组构和特征,清晰呈现了陆坡-海盆砂体展布的规律,可为建立南海北部新近纪早期深水扇形成模式提供参考,有助于指导南海深水油气勘探工作。     

世界主要深水含油气盆地储层特征

世界深水盆地油气资源丰富,良好的储层是形成较大油气藏的必要条件.以大量调研资料为基础,对大西洋区域的墨西哥湾、巴西东部边缘、非洲西海岸、挪威中部陆架及新特提斯区域的澳大利亚西北陆架、中国南海、孟加拉湾、地中海(尼罗河三角洲)8个地区的24个深水含油气盆地储层特征进行了综合分析,归纳总结了这些深水含油气盆地中主力储层的形...     

Distribution, habitat use and ecology of deepwater Anemones (Actiniaria) in the Gulf of Mexico

The distribution of deepwater Actiniaria is poorly known. Rarely are these organisms identified to family, as this requires both well-preserved specimens and taxonomic expertise. Ecological information is similarly lacking. From the results of a comprehensive surveying program in the deep Gulf of Mexico, we report the occurrence of nine species of Actiniaria. For the most abundant four of these, we plot distributions and discuss habitat use, morphological variation, and feeding strategies. Actiniaria in the Gulf appear to have broad, basin-wide distributions with little depth preference. Faunal biomass is highest in the NE Gulf within submarine canyons or at the base of slope escarpments. Attachment mode is mostly opportunistic on various types of hard substrata, including trash. Sediment-dwelling forms are very abundant at an organically rich site within a large submarine canyon.     

Facies and sequential organisation of a mudstone-dominated slope and basin floor succession: the Gull Island Formation,Shannon Basin,Western Ireland

The lower part of the Carboniferous Shannon Basin of Western Ireland contains a deep-water succession which exceeds 1200 m in thickness that comprises five lithologically different units deposited within a confined, relatively narrow basin: (i) a calciclastic debris-flow and turbidite unit formed by resedimentation from nearby carbonate platforms, (ii) a siliciclastic black shale succession with former source potential which onlaps basin margins (Clare Shales), (iii) a sandstone-dominated turbidite formation, controlled by ponded accommodation and deposited axially in the basin (Ross Formation), (iv) a mudstone-rich turbidite-bearing succession, which onlaps basin margins (lower Gull Island Formation), and (v) a mudstone-dominated prograding slope succession (upper Gull Island Formation and lower Tullig Cyclothem), which grades transitionally upwards into deltaic deposits. The top unit records progradation at a time when basin differential subsidence had diminished significantly and local basin topography did not control deposition. The two upper mudstone-dominated units are different in terms of both sandstone content and their genetic significance within the overall basin-fill, and their potential relevance as reservoir analogues.The lower part of the Gull Island Formation contains three principal facies associations: (a) shallow turbidite channels and sheets representing channel margin and levee deposits, (b) mud-rich slumps, and (c) less than 1 m thick, rare, hemipelagic shales. More than 75% is deformed by soft-sediment deformation, but only to a smaller degree affecting sandstone units. The turbidites record transport to the ENE, along the axis of the basin, while the slumps were derived from an unstable northern slope and transported transversely into the basin towards the southeast. The distribution of turbidite sandstone and slumps is inversely proportional. Sandstones decrease in importance away from the basin axis as slumps increase in number and thickness. The lower part of the Gull Island Formation is interpreted to record progressive fill of a deep basin controlled by local, healed slope accommodation with onlap/sidelap of the basin margins. The instability resulted from a combination of fault-controlled differential subsidence between basin margin and basin axis, and high rates of sedimentation.The upper part of the Gull Island Formation is entirely dominated by mudstones, which grade upwards into siltstones. It contains rare, up to 15 m thick, isolated channels filled by turbidites, showing transport towards the east. The upper part records easterly progradation of a deep-water slope genetically tied to overlying deltaic deposits, and controlled by regional accommodation.The contrasts between the lower and upper parts of the Gull Island Formation show that onlapping/sidelapping turbidite successions have reservoir potential near basin axes, but that prograding deep-water slopes are less likely to have reservoir potential of significance. A suggested regional downlap surface between the two parts is a significant break and marker in terms of reservoir potential.     

Balancing deformation in NW Borneo: Quantifying plate-scale vs. gravitational tectonics in a delta and deepwater fold-thrust belt system

Recent GPS measurements demonstrate that NW Borneo undergoes 4–6 mm of plate-scale shortening a year, which is not accommodated by plate-scale structures. The only geological structure in NW Borneo described to accommodate on-going shortening is the Baram Delta System located on the outer shelf to basin floor. Delta toe fold-thrust belts are commonly thought to be caused by margin-normal compressional stresses generated by margin-parallel upslope gravitational extension.     

Structural features and hydrocarbon-bearing potential of gulf of Mexico continental slopes adjacent to the United States

With respect of its structure, the Gulf of Mexico basin is heterogeneous. The following individual basins and subbasins can be distinguished; (1) Mississippi-Louisiana; (2) Gulf Coast within the boundaries of Texas and New Mexico; (3) Mexican Gulf Coast and adjacent system of foredeeps; (4) Yucatan subbasin; (5) Cuba-Bahamas system of foredeeps. Regional seismic studies reveal a close relationship between salt movements and sedimentation. Salt bodies represent excellent cap rocks for hydrocarbon fluids. Anticline folds termed “turtle” structures forming a system of belts appear in the deep parts of the gulf. These structures host large reserves of hydrocarbons, which are concentrated in the Paleogene-Miocene turbidite reservoirs with a porosity approximately 30% overlain by excellent cap rocks (salt, clay) with permeability exceeding 3 darcy. Three productive zones are defined: (1) the folds of the Mississippi River fan; (2) the Perdido belt of anticline folds; (3) Florida. The Paleogene and Miocene-Pliocene-Pleistocene sediments developed on the continental slopes of the Gulf of Mexico basin are the areas most promising with respect to hydrocarbon deposits. On January 1, 2006, the offshore oil production was 53 million tons and the gas production 40 billion cubic meters. Total prospective oil and gas reserves are estimated to be 5.5 billion tons and 4.7 trillion cubic meters, of which over 50% of oil and 1/3 of gas are expected to be discovered on the continental slope.     

The shape of deep-water siliciclastic systems: A discussion

Deep-water siliciclastic systems are classified primarily on their shape as: submarine fans with well developed or poorly developed morphology, slope drapes, for example, over relatively stable basin margins, fault-scarp aprons, canyons and large channels, under-supplied sheet systems such as abyssal plains, non-fan ponded systems such as over-supplied perched basins, and fan deltas. Collectively, or separately, these systems may form sedimentary basin fills that can be over or under-supplied with respect to the sediment input although most systems will tend toward over-supply/overflow with time. Finally, the sum total of the siliciclastic systems and basins can be used to define the tectonic milieux such as passive, strike-slip and convergent margins.     

深水褶皱冲断带的构造变形和油气地质特征

深水褶皱冲断带是目前全球油气勘探的重要领域,其构造变形和油气地质特征是勘探研究的主要内容。通过对不同地区深水褶皱冲断带的地震剖面解释和综合分析,结合沉积特征对其构造样式、变形特征和石油地质特征进行了研究。研究表明,在主动大陆边缘和被动大陆边缘存在4种不同构造样式的深水褶皱冲断带,即:主动大陆边缘型深水褶皱冲断带;被动大陆边缘背景下的泥岩滑脱型、盐岩滑脱型和重力垮塌滑动型深水褶皱冲断带。由于他们具有不同的驱动机制、构造特征和演化特征,导致了其含油气性差别较大。主动大陆边缘背景下发育的深水褶皱冲断带主要发育倾向陆地的逆冲断层、叠瓦构造以及相关的褶皱构造,缺乏有效的烃源岩和储层。被动大陆边缘背景下发育的深水褶皱冲断带可以划分为伸展区、过渡区和挤压区3部分,并发育相关构造,其中泥岩滑脱型和盐岩滑脱型深水褶皱冲断带已经有大量的油气发现。     

Some faulting patterns along the continental slope off Israel and their tectonic significance

A high resolution seismic survey was carried out on the continental slope of Israel, NW of Caesarea. The area was studied in order to map the tectonic elements of the Dor structure, and to extrapolate and suggest a structural model of the tectonics of the continental slope of the SE Mediterranean since the Late Miocene. It was found that the continental slope was affected by two faulting systems—NW trending strike-slip faults and NNE trending normal faults. Faults of both systems are associated with numerous slumps along the slope. However, the NW trending faults belong to a faulting system of similar trend that abounds in the adjacent continent and extends northwestwards across the continental shelf and slope to the continental rise. The NNE trending faults form the shelf-edge faulting system that was associated with the subsidence of the eastern Mediterranean basin since the Pliocene. Thus the continental slope is not only a morphological transition zone but also a tectonic one, showing the influence of both the continental and the oceanic structural regimes in the SE Mediterranean region.     

南海北部白云深水区水道与朵体沉积序列及演化

近年来,深水水道、朵体已成为油气勘探的重要目标,南海北部白云深水区发育大量深水水道-朵体沉积体系。研究现今陆坡深水沉积过程有助于揭示深海沉积分布、沉积演化规律。在回顾深水层序地层研究的基础上,利用近地表高分辨率三维地震资料所揭示的地震反射(下超点和上超点迁移)特征研究深水沉积序列,初步探讨不同时期深水水道-朵体体系沉积动力机制,深水水道-朵体体系具有垂向的前积、加积和退积特征,并提出一种深水水道-朵体体系沉积层序模式,低位体系域早期,发育碎屑流或滑块为主的水道-朵体体系,后期则转化为浊流为主的水道-朵体体系。在深水等时地层格架内研究现代深海沉积过程及其产物,对深水储层预测具有十分重要的意义。     

Interactions between the Laramide Foreland and the passive margin of the Gulf of Mexico: Tectonics and sedimentation in the Golden Lane area,Veracruz State,Mexico

This paper focuses on the analyses of the clastic sedimentary infill of the Coastal Plain of Eastern Mexico, which initiated synchronously with the Laramide orogeny in the vicinity of the Golden Lane. Results of these analyses are used as boundary conditions for calibrating/interpreting seismic profiles across more distal depocenters in the offshore of the Gulf of Mexico, from the sea shore and continental slope in the west to the abyssal plain in the east. The objective of the study is to better predict the reservoir distribution in the Deep offshore Basin of the Gulf of Mexico (DBGM), in order to explore for petroleum.     

Impact of oil and gas vents and slicks on petroleum exploration in the deepwater Gulf of Mexico

Active petroleum vents and slicks have been identified in the deep water of the northern Gulf of Mexico using numerous techniques. The occurrence and distribution of these petroleum vents are strongly influenced by the local geological framework—especially the presence of vertical migration pathways into shallow sediments. Oil and gas vents may be more useful for establishing the existence of petroleum generation on a regional scale and for evaluating the gross properties of oil migrating in the subsurface than for appraising the exploration value of individual prospects. Knowledge about petroleum venting in the deepwater Gulf of Mexico has proven to be an important element of the successful exploration activities there.     

Seismic characteristics, morphology and formation of the ponded Fangliao Fan off southwestern Taiwan, northern South China Sea

Using bathymetry and reflection seismic profiles this study reveals the nature of the modern ponded Fangliao Fan within a framework of sediment infilling of an intra-slope basin on a tectonically active margin off southwestern Taiwan. The Fangliao Fan begins at the mouth of Fangliao Canyon at a water depth of 900 m and terminates down-slope at the escarpment of a linear ridge north of the Kaoping Slope Valley at a water depth of about 1,100 m, sediment gravity flows being prevented from farther down-slope transport due to ponding against this bathymetric high. The fan appears as a distinct basinward-opening triangular depocenter confined by ridges on both sides and the NW–SE trending ridge aligned normal to the elongation of the fan. These topographic ridges were formed by mud-diapiric intrusions. The external form of the ponded Fangliao Fan is characterized by a fan-valley fill pattern that has a concave cross-sectional morphology, in contrast to typical mounded fans deposited on slope-basin plains having a smooth topography. Sediment episodically funneled through the Fangliao Canyon from upslope areas and derived from the flanks of the mud-diapiric ridges are mainly transported by mass movement before being re-dispersed by unconfined channels to infill the intra-slope basin, thereby building up channelized fan complexes with poorly developed levees. The sediment flows from the mouth of Fangliao Canyon flow down-slope along the west flank of the Fangliao Ridge. In the process, a feeder channel has been eroded into the seafloor along which sediment is transported to the distal parts of the fan. Sediment west of the feeder channel is mainly redistributed by mass movement and/or fan channels to fill up the irregular topographic low in the slope. Due to a very low sediment supply, Fangliao Fan represents a starved ponded slope fan. As such it provides insights into the processes by which ponded fans develop and can therefore serve as an analog for similar fans developed on topographically complex slopes elsewhere. The morpho-structural features of the Fangliao Fan resulted from the interplay between sediment supply, uplift of the mud-diapiric ridge, mass movements, and alternating incision and deposition.     

美国墨西哥湾海上油气发现与生产评述

评述了美国墨西哥湾深海油气储量、墨西哥湾原有的油气发现、墨西哥湾浅水和深水的油气发现统计、深水钻井重获许可后开发的新进展、墨西哥湾油田原油生产数据以及新发现开始生产石油的情况.     

Movement of sediment on the Gulf of Mexico,continental slope and upper continental shelf

Abstract

Grain size, coarse fraction analyses, and depositional environment as interpreted from microfauna are related to the character of sparker reflections at the location of core holes drilled by Exxon, Chevron, Gulf, and Mobil on the continental slope of the northern Gulf of Mexico. Continuous sparker reflections are correlated with slowly deposited, evenly bedded sediments containing bathyal faunas. The coarse fraction is dominated by the tests of foraminifera. Discontinuous, discordant reflections and diffractions are correlated with sediments more rapidly emplaced in the bathyal environment of the continental slope by slumping and sliding from the continental shelf. Their coarse fraction is dominated by terrigenous sand grains. A large portion of the volume of continental slope sediments appears to consist of these “displaced”; sediments, including an area 3–24 km wide and 80 km long, southeast of Corpus Christi, Texas. Comparable processes of movement of sediments are interpreted on the continental shelf south of the Southwest Pass of the Mississippi River. Bathymetry in this area is characterized by a series of subaqueous “gullies”; radiating from the river mouth and leading to terraces at their southern extremities. Side‐scan sonar and PDR surveys show a rough bottom in these “gullies”; and terraces, as contrasted with a relatively smooth bottom elsewhere. The rough bottom is interpreted as indicative of slump and creep of the sediments from shallower water. Some foundation soil borings in this area south of Southwest Pass find a low‐strength material gradually increasing in strength with depth. Other borings find a “crust”; of anomalously strong material 8–15 m below the mudline. The microfauna recovered from the “crust”; has moved to its present position by slump or creep from shallower water along a pattern comparable to the gullies shown in the present‐day bathymetry.