Discovery and inspiration of large-and medium-sized glutenite-rich oil and gas fields in the eastern South China Sea:An example from Paleogene Enping Formation in Huizhou 26 subsag,Pearl River Mouth Basin

Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.

Features of sampling stream sediments of large river valleys under cryolithogenesis conditions in the Balygychan-Sugoy trough,North-East of Russia

Comprehensive research has been implemented to raise the efficiency of the geochemical survey of stream sediments(SSs)that formed under the cryolithogenesis conditions.The authors analysed the composition,structure and specific features of the formation of exogenous anomalous geochemical fields(AGFs)identified through SSs of large river valleys of IV order.In our case,these were the valleys of Maly Ken,Ken and Tap Rivers.These rivers are located in the central and southern parts of the Balygychan-Sugoy trough enclosed in the Magadan region,North-East of Russia.The authors proposed a new technique to sample loose alluvium of SSs in the large river valleys along the profiles.The profiles were located across the valleys.The AGFs of Au,Ag,Pb,Zn,Sn,Bi,Mo and W were studied.Correlations between elements have been established.These elements are the main indicator elements of Au-Ag,Ag-Pb,Sn-Ag,Mo-W and Sn-W mineralization occurring on the sites under study.The results obtained were compared with the results of geochemical surveys of SSs.It is concluded that the AGFs recognized along the profiles reflect the composition and structure of eroded and drained ore zones,uncover completely and precisely the pattern of element distribution in loose sediments of large water flows.The alluvium fraction<0.25 mm seems to be most significant in a practical sense,as it concentrated numerous ore elements.Sampling of this fraction in the river valleys of IV order does not cause any difficulty,for this kind of material is plentiful.The developed technique of alluvium sampling within large river valleys is efficient in searching for diverse mineralization at all stages of prognostic prospecting.It is applicable for geochemical survey of SSs performed at different scales both in the North-East of Russia,as well as other regions with similar climatic conditions,where the SSs are formed under the cryolithogenesis conditions.

Impacts of Coastal Reclamation on Natural Wetlands in Large River Deltas in China

Little information is available on the impacts of coastal reclamation on wetland loss in large-river deltas at a regional scale.Using remote sensing data of coastal wetland and reclamation in four deltas in China from 1978 to 2014, we tracked their continuous area changes in four periods: 1978–1990, 1990–2000, 2000–2008, and 2008–2014. The areal relation between wetland loss and reclamation was quantified and used to identify coastal reclamation mode intensity coupled with another three indicators: reclamation rate,accretion rate and land-use intensity of coastal reclamation. The results showed that coastal reclamation driven by economic development reduced, or even reverse the original growth of delta which was determined by the offset between wetland acceleration rate and wetland loss rate. Generally, the area of reclamation showed a positive linear correlation with the area of wetland loss. The findings imply that human activities should control reclamation rate and intensity to alleviate total wetland loss and maintain wetland ’net gain’.Inappropriate coastal reclamation modes can magnify total wetland loss;therefore, coastal reclamation with a slow increment rate and low impervious surface percent is of great importance for sustainable development in future coastal management.

Damming of Large River by Debris Flow: Dynamic Process and Particle Composition

The frequency and extent of debris flows have increased tremendously due to the extreme weather and the Wenchuan earthquake on May 12, 2008. Previous studies focused on the debris flow from gullies damming the mountain streams. In this paper, an equation for the run-out distance of debris flow in the main river is proposed based on the dynamic equation of debris flow at different slopes given by Takahashi. By undertaking field investigations and flume experiments, a new calculation method of the volume of debris flow damming large river is obtained. Using the percolation theory and the renormalization group theory it was deduced that the large particles should comprise more than 50% for forming a stable debris flow dam. Hence, the criteria of damming large river by debris flow is presented in terms of run-out distance and grain composition which was then validated through the event of damming river by debris flow at Gaojia gully, the upper reaches of the Minjiang River, Sichuan, China, on July 3, 2011.

Theoretical analyses on bed topography responses in large depth-to-width ratio river bends with constant curvatures

Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-width ratio, a theoretical model is established with the coupling of Navier-Stokes （N-S）~ sediment transport, and bed deformation equations. The flow characteristics and bed response of river are obtained with the perturbation method. The research results show that, under the effect of two- dimensional flow disturbance, the bars and pools present the regular response. For a given sinuousness, the amplitude of the bed response can be used as a criterion to judge the bedform stability. The effects of the Reynolds number, disturbance wavenumber, sinuousness, and bed morphology gradient on the bed response development are described.

Flow resistance in the channel-bar landscape of large alluvial rivers

Accurate approaches for estimating flow resistance in large alluvial rivers are fundamental for simulating discharge,sediment transport,and flood routing.However,methods for estimating riverbed resistance and additional resistance in the channel-bar landscapes remain poorly investigated.In this study,we used in situ river bathymetry,sediment,and hydraulic data from the Shashi Reach in the Yangtze River to develop a semi-empirical approach for calculating flow resistance.Our method quantitatively separates flow resistance into riverbed resistance and additional resistance and shows high accuracy in terms of deviation ratio(~20%),root-mean-square error(~0.008),and geometric standard deviation(~3).Additional resistance plays a dominant role under low-flow conditions but a secondary role under high flows,primarily due to the reduction in momentum exchange in channel-bar regions as discharge increases.Riverbed resistance first decreases and then increases,which might be attributed to bedform changes in the lower and transitional flow regimes as flow velocity increases.Overall,our findings further the understanding of dynamic changes in flow resistance in the channel-bar landscapes of large river systems and have important implications for riverine ecology and flood management.

Comparative research on integrated development of large river basins:a case study of the Yangtze and the Rhone

Since 2001, the French and Chinese researchers have done a cooperative research on the comparison of integrated development of large fiver basins. The Yangtze River was chosen as a crux of this research and linked with other older river experiments like the Rhone, the Nile and the Mississippi. This research includes not only the environmental issues but also economic and social issues. One special issue journal has been published in French for our research results. Other two collective and comparative books in French and Chinese will be finished at the end of this year. In the future, the comparison should be widened to Italy （the Po）, Egypt （the Nile development planning） and the United States （the Mississippi Basin） and we would like to enlarge our research group and want to link up different teams and research projects, in order to get a global understanding of large fiver regions phenomenon.

A mechanism for the origin and development of the large-scale dunefield on the right flank of the lower reach of Laoha River,Northeast China

By viewing satellite imagery, a striking large-scale dunefield can be clearly perceived, with a size of nearly 63 km long and 11 km wide, and trending NE-SW, on the right flank of the lower Laoha River, Northeast China. By means of remote sensing imagery analysis and field observation as well as a comparison with a small-scale dunefield on the right flank of the lower Xiangshui River, analogous to the case of the lower Laoha River, this paper presents a new mechanism for its origin and development. The results show that： （1） the large-scale dunefield bears a tile-style framework overwhelmingly composed of transverse barchanoid ridges perpendicular to the predominant winds, and inlaid diverse blowouts. （2） The small-scale dunefield, referred to as a primary structural unit of the large one, is typical of an incipient dunefield, following the same rules of evolution as the larger. （3） A succession of barchanoid ridge chains can steadily migrate downwind in much the same manner as surface wave propagation in air or water stimulated by an incised valley, and ultimately tend to bear roughly the same wavelength and amplitude under stable climate and hydrologic regimes. （4） The first ridge chain acquires its sand source substantially from the downwind escarpments exposing the loose Quaternary sandy sediments to the air, while the ensuing ridges derive their sands dominantly from in situ deflation of the underlain Quaternary loose sandy sediments in blowouts, partly from the upwind ridges through northern elongated horns. Theoretically, the sands from riparian escarpments can be transported by wind to the downwind distal end of a dunefield after sufficient long du- ration. （5） The lower Laohahe region experienced probably three significant climatic changes in the past, corresponding to the three active dune belts, suggesting that once a large-scale dunefield occurs, it is nearly impossible to be completely stabilized, at least in its central portions. At present, seasonal shrinkage and stagnation of the lower Laoha River, wide-spread farming and afforestation in the valley, and establishing windbreaks downwind of the valley as well as surrounding the dunefield, appear to have significantly modified local flow fields and sand sources, engendering significant degradation of the dunefield.

The second large hydropower station on Lancang River dammed successfully

ＴｈｅｓｅｃｏｎｄｌａｒｇｅｈｙｄｒｏｐｏｗｅｒｓｔａｔｉｏｎｏｎＬａｎｃａｎｇＲｉｖｅｒｄａｍｍｅｄｓｕｃｃｅｓｓｆｕｌｌｙＴｈｅｓｅｃｏｎｄｃａｓｃａｄｅｈｙｄｒｏｐｏｗｅｒｓｔａｔｉｏｎｏｎＬａｎｃａｎｇＲｉｖｅｒ，ｔｈｅＤａｃｈａｏｓｈａｎＨ...

Validating the Runoff from the PRECIS Model Using a Large-Scale Routing Model

The streamflow over the Yellow River basin is simulated using the PRECIS （Providing REgional Climates for Impacts Studies） regional climate model driven by 15-year （1979-1993） ECMWF reanalysis data as the initial and lateral boundary conditions and an off-line large-scale routing model （LRM）. The LRM uses physical catchment and river channel information and allows streamflow to be predicted for large continental rivers with a 1°×1° spatial resolution. The results show that the PRECIS model can reproduce the general southeast to northwest gradient distribution of the precipitation over the Yellow River basin, The PRECIS- LRM model combination has the capability to simulate the seasonal and annual streamflow over the Yellow River basin. The simulated streamflow is generally coincident with the naturalized streamflow both in timing and in magnitude.

Large-scale Migration of Fluids toward Foreland Basins during Collisional Orogeny: Evidence from Triassic Anhydrock Sequences and Regional Alteration in the Middle-Lower Yangtze Area

The middle-lower Yangtze area underwent a series of complex tectonic evolution, such as Hercynian extensional rifting, Indosinian foreland basining, and Yanshanian transpression-transtension, resulting in a large distinctive Cu-Fe-Au metallogenic belt. In the tectonic evolution, large-scale migration and convergence of fluids toward foreland basins induced during the collisional orogeny of the Yangtze and North China continental blocks were of vital importance for the formation of the metallogenic belt. Through geological surveys of the middle-lower Yangtze area, three lines of evidence of large-scale fluid migration are proposed: (1) The extensive dolomitic and silicic alteration penetrating Cambrian-Triassic strata generally occurs in a region sandwiched between the metallogenic belt along the Yangtze River and the Dabie orogenic belt, and in the alteration domain alternately strong and weak alteration zones extend in a NW direction and are controlled by the fault system of the Dabie orogenic belt; it might record the locus of the activities of long-distance migrating fluids. (2) The textures and structures of very thick Middle-Lower Triassic anhydrock sequences in restricted basins along the river reveal the important contribution of the convergence of regional hot brine in restricted basins and the chemical deposition or their formation. (3) Early-Middle Triassic syndepositional iron carbonate sequences and Fe-Cu-Pb-Zn massive sulfide deposits alternate with anhydrock sequences or are separated from the latter, but all of them occur in the same stratigraphic horizon and are intimately associated with each other, being the product of syndeposition of high-salinity hot brine. According to the geological surveys, combined with previous data, the authors propose a conceptual model of fluid migration-convergence and mineralization during the Dabie collisional orogeny.

Sampling-Based Approaches to Estimating Two-Dimensional Large Wood Area from UAS Imagery

Large in-stream wood (LW) is a critical component of riparian systems that increases heterogeneity of flow regimes and provides high quality habitat for salmonids and other fishes. We present four sampling-based methods to estimate two-dimensional LW for a 61-hectare river restoration project on the South Fork McKenzie River near Rainbow, OR (USA). We manually delineated LW area, from unoccupied aircraft systems (UAS) multispectral imagery for 40 randomly selected 51.46 m2 hexagonal plots. Seven auxiliary variables were extracted from the imagery and imagery derivatives to be incorporated in four estimators by summarizing spectral statistics for each plot including Random forest (RF) classification of segmented imagery (Cohen’s kappa = 0.75, balanced accuracy = 0.86). The four estimators were: difference estimator, simple linear regression estimator with one auxiliary variable, general regression estimator with seven auxiliary variables, and simple random sample without replacement. We assessed variance of the estimators and found that the simple random sample without replacement produced the largest estimate for LW area and widest confidence interval (17,283 m2, 95% CI 10,613 - 23,952 m2) while the generalized regression approach resulted in the smallest estimate and narrowest confidence interval (16,593 m2, 95% CI 13,054 - 20,133 m2). These methods facilitate efficient estimates of critical habitat components, that are especially suited to efforts that seek to quantify large amounts of these components through time. When combined with traditional sampling methods, classified imagery acquired via UAS promises to enhance the temporal resolution of the data products associated with restoration efforts while minimizing the necessity for potentially hazardous field work.

内河中游区大型沉管隧道建造关键新技术——以襄阳鱼梁洲隧道为例

为解决内河中游区沉管隧道建造面临的河床冲刷强、强透水地层深厚、防洪要求高等问题,依托襄阳鱼梁洲沉管隧道工程,通过工程调研、理论分析、物模试验、数值模拟、现场测试等手段,对内河沉管隧道建造关键技术进行创新及应用,首次形成如下创新成果:1)提出沉管隧道冲刷安全量化评价方法,给出沉管结构横向稳定性安全系数等5项评价指标及其评价标准体系,填补了沉管隧道防冲安全量化评价方法的空白;2)研发利用管周摩擦力抵抗止水带回弹力的摩擦止推型最终接头,解决常规陆域接头需设置大型圬工结构的问题;3)研发并量产可满足0.3 MPa外水压水密性、100年设计使用寿命的沉管接头外侧止水带国产化产品,其百年应力松弛衰减率仅25.5%,预测使用寿命144年,使中国实现沉管隧道全产业链技术的国产化;4)提出整体式管节不设后浇带全断面顺浇预制工法,实现沉管结构预制工效提高52%、结构接缝减少61%、浇筑裂缝减少60%;5)在内河沉管隧道中采用先铺卵石垫层基础,并研发出全浮式高精度先铺卵石基床整平船;6)研发应用沉管无焊接装配式端封门和柔性水袋压载水系统,可实现舾装设施的便捷循环使用和施工效率的提升。

南海东部富砂砾型大中型油气田发现与启示——以珠江口盆地惠州26洼古近系恩平组为例

基于珠江口盆地惠州凹陷油气勘探实践,通过烃源岩地球化学指标测定、储集体发育形貌恢复及镜下岩矿表征、圈闭封盖指标实测比对、原油生物标志化合物提取、凝析气成因判别及成藏条件解剖,系统分析惠州26洼古近系恩平组油气资源潜力、大型砂砾岩优质储集层发育特性、断裂圈闭有效性及油气运聚成藏模式,总结南海东部古近系富砂砾型大中型油气田的形成条件及勘探方向。研究表明:(1)洼内古近系文昌组发育“面积广、厚度大”的半深湖—深湖亚相优质烃源岩,具有“早期大量生油、晚期大量排气”的典型倾油型烃源岩排烃特征,为恩平组油气成藏提供了充足的物质基础;(2)洼内断裂陡坡带与转换带联合控制下近源规模性砂砾岩体储集层非均质性强,具有“有利相带-颗粒组分-微裂缝”三元分级控储特性,等粒、低泥质(含量小于5%)、高含量长石组分及近断裂组合的(水下)分流河道有利于甜点储集层发育;(3)稳定湖泛泥岩封盖下的走滑增压型圈闭是油气保存的必备条件,斜交主应力的北东及近东西向断裂控圈效果最优;(4)优质烃源岩-断裂输导/封堵-砂砾岩储集层时空配置共同控制油气富集程度,自上而下划分为低充满带、过渡带和高充满带3个油气聚集单元,且近增压型通源断裂带河道主体区利于规模性油气富集。研究成果为珠江口盆地恩平组规模性富砂砾型油气藏勘探指明了新方向,并实现了油气勘探重大突破。

长江和西江大型船闸通航运行关键技术研究与展望

保障长江和西江大型船闸通航枢纽的畅通、安全、高效意义重大。针对闸-船-航道三要素影响因素多、耦合性强,航道水流非定常,水位变幅高、变率快等难题,研究大型船闸通过能力多维分析建模与仿真、非恒定流下船闸航道水动力学特性分析、多约束非定常船-闸水动力学精细化建模等方法,攻克了复杂多变条件下船闸中间航道通航、新标准船型与船闸协同下快速过闸、大型船闸扩能建设工程设计等船闸通过能力提升关键技术,以及大型船闸联动安全控制、关键设备运行智能监测、通航安全风险防控等联动运行安全控制关键技术,构建长江和西江大型船闸高效安全通航工程技术体系,并建立通航调度与安全一体化管控平台。从多尺度动力学、数字孪生、智能化与国产化和绿色生态技术等方面,展望大型船闸通航运行科技发展的方向。

两类阈值法识别的东江流域水文干旱形成与演化过程差异

基于东江流域上、下游控制断面龙川站和博罗站1956—2010年逐月流量及流域内枫树坝、新丰江和白盆珠水库逐月入库和出库流量数据,采用水库调控流量还原法,结合动态阈值法和固定阈值法识别水文干旱,系统分析了两类阈值法识别的水文干旱形成与演化过程的差异及其对大型水库调控的响应规律。结果表明:两类阈值法针对的干旱本底概念不同,识别的水文干旱年内分布和干旱开始、峰值和终止月份差异显著;动态阈值法识别的水文干旱在年内各月均匀分布,固定阈值法识别的水文干旱集中分布在枯水季(10月至次年3月),干旱峰值多出现在11月至次年2月,干旱终止月份以汛前期3、4月为主,干旱开始、峰值和终止月份与研究区水文丰枯转换月份较吻合;两类阈值法均能较好地表征水文干旱的发展和恢复过程及其对大型水库调控的响应特征,即水库调控在缩短干旱历时、降低干旱烈度、延后水文干旱开始和峰值月份以及提前干旱终止月份等方面发挥重要作用。

汉江流域夏季降水演变的水汽输送驱动机制

为应对气候变化下愈加频繁和剧烈的干旱事件,保障跨流域调水工程水源及当地用水安全,亟需对汉江流域这一国家重要战略水源地的降水过程变化进行研究。汉江流域夏季降水占全年降水的40%~50%。本研究利用拉格朗日混合单粒子轨道模型对汉江流域1959—2022年夏季降水的水汽输送过程及其大气环流背景进行分析,以揭示汉江流域夏季降水变化的原因。研究发现,历时72 h以上降水占夏季总雨量的44.6%,在过去半个多世纪中其频次和雨量均呈现显著下降趋势,是汉江流域降水减少的主要原因。对水汽输送过程的模拟分析表明,中国南海、西太平洋、中国东部是流域夏季降水的水汽来源,贡献率分别为:34.7%、28.7%、27.2%。对比不同历时降水的水汽输送过程,发现降水历时越长,来自中国南海和西太平洋的水汽贡献率越高。尽管来自西太平洋的水汽呈现显著增加,但来自中国南海的水汽显著下降,使得72 h以上降水仍然呈现下降趋势。分析大尺度气候指数与各水汽输送路径贡献率的相关性,发现中国南海水汽贡献减小与西太平洋副热带高压面积、强度增加呈显著负相关。这证实了近年来西太副高的增强和扩张对汉江流域夏季降水减少起到促进作用。

东江流域控制性水工程联合调度策略与机制探讨

近年,东江流域旱涝事件并存,防洪与供水安全形势严峻,三大水库和干流梯级电站是东江流域水旱灾害防御中的重要水利工程。收集流域水工程多年运行经验、案例、数据,综述东江流域控制性水工程联合调度在管理体制、防洪调度、水量调度等方面的研究、实践现状,通过数学模型、统计等方法,对现状调度体制与机制中存在的问题进行分析。从管理、技术、研究等角度提出建议与对策。

基于分布式水文模型的水源涵养不同功能评估方法——以渭河涵养区为例

为了实现水源涵养量计算和不同功能的综合评估,基于分布式水文模型(WEP-L)提出了一种新方法,即利用WEP-L模型计算次降水过程中降水量和地表产流、冠层截留量的差值作为水源涵养量,并分别评估削洪(地表径流量)、补枯(地下径流量)、维持植被生态系统用水(植被蒸腾量)等不同水源涵养功能的评估方法。为了验证该方法的合理性,以渭河流域咸阳站以上区域为例,对比了该方法和InVEST模型方法的计算结果,由于两种方法在评估内容和使用模型上都存在差异,为了保证计算结果的可比性,先对比了基于相同评价内容的WEP-L模型法I和InVEST模型方法,再对比了基于不同评价内容的WEP-L模型法I和WEP-L模型法II,结论如下:基于相同评价内容的WEP模型法I和InVEST模型法计算结果数值接近,研究区2000—2018年水源涵养量年均值分别为12.43 mm(5.76亿m~3)和12.08 mm(5.6亿m~3),两种方法所得结果空间分布特征相似,稍有差异之处与InVEST模型的参数没有经过本地化处理有关;基于不同评价内容的WEP-L模型法Ⅰ和WEP-L模型法II计算结果数值相差较大,研究区2000—2018年水源涵养量均值分别为12.43 mm和432.57 mm,空间分布特征上有差异的地方分布于研究区的北部、东部及东北部,主要与两种方法评价时是否考虑蒸散发有关。WEP-L模型法II评估结果中削洪、补枯、维持植被生态系统用水等功能多年变化趋势分别为:2006—2010年期间增加、2012年以后下降以及增加。2012年后补枯功能和维持植被生态系统用水功能之间可能存在权衡关系。通过不同方法计算结果差异原因分析,证明了基于WEP-L模型的不同涵养功能评估方法的合理性,其结果也可为渭河涵养区水资源和生态保护策略的制定提供更多依据。