The source and formation characteristics of the Zhujiadun gas reservoirs in the Yancheng Sag, Subei Basin

The Yancheng Sag is a favorable exploration area in the Subei Basin. However, the key geological understanding of the natural gas source and reservoir formation characteristics of the sag is still controversial. Based on a set of organic geochemical experiments conducted on natural gas and associated condensate oil of the first member of the Funing Formation (E1f1) in well YCh5 and well data analysis, the oil-gas resources and reservoir formation model in the Zhujiadun gas reservoir in the Yancheng Sag, Subei Basin, were investigated. The results of this study are as follows. (1) The natural gas in the Zhujiadun gas reservoir is dry gas with high methane content, low heavy hydrocarbon content, and high maturity. The characteristics of carbon and hydrogen isotopes in the natural gas indicate that the natural gas is oil-cracked gas, which mainly originates from the source rocks of the Permian Qixia Formation. (2) The condensate oil from well YCh5 with a high degree of maturity has a high pristane/phytane ratio, low gamma-paraffin abundance, and low tricyclic terpene abundance, indicating a mixture of the Upper Paleozoic condensate oil and Cenozoic crude oil. The saturated and aromatic hydrocarbons have similar δ13C values to the Cenozoic continental crude oil. These features suggest two sources of condensate oil. (3) Oils generated from the source rocks of the Qixia Formation were cracked into highly mature gas after deep burial, which migrated along large faults into the sandstones of the E1f1 and K1t1 members. This type of reservoir was effectively preserved beneath the overlying mudstone cap rocks. Therefore, it can be inferred that a play fairway might occur in the eastern zone of the faults connected to the Paleozoic source rocks in the Yancheng Sag since this zone has similar petroleum geological conditions to well YCh5. Therefore, this zone is a favorable area for further exploration.

Sedimentary Evolution and Transgressions of the Western Subei Basin in Eastern China since the Late Pliocene

Sedimentary sequences in the Subei Basin are complex and have been affected by interactions between the ocean and rivers since the Late Pliocene, including the Yellow River, Huaihe River, and the Yangtze River. This sedimentary evolution, in particular the timing of Pleistocene transgressions, has long been a matter of controversy owing to the lack of precise chronological evidence. The aim of this study is to explore the evolution of the sedimentary environment throughout the past 3.00 Ma in this region on the basis of a comprehensive analysis of particle size and foraminifera and ostracods collected in the TZK9 core from the Subei Basin combined with geochronological studies of magnetostratigraphy, AMS^(14)C and optically stimulated luminescence(OSL). The results show that fluvial facies in the sedimentary environment from 3.00 to 1.01 Ma. There were fluvial facies and reflects six sea-level high stands from 1.01 to 0.25 Ma. The study area was affected by four large-scale transgressions since 0.25 Ma. The four marine sedimentary layers known as DU7(buried at 48–52 m), DU5(buried at 35–41 m), DU3(buried at 16–23 m), and DU1(buried at 2–4 m) are recorded in the MIS7(210–250 ka), MIS5, MIS3, and Holocene, respectively. The magnitude of the DU5 transgression was identical to that of the DU3 transgression, both were larger than the DU7 transgression, and the DU1 transgression was the weakest. The variation of transgression strength reflects the influence of global changes in sea level, tectonic subsidence, shell ridges, and sand dams. In the TZK9 core, we found evidence of seven sea-level high stands from the Early–Middle Pleistocene, and the first one caused by regional rapid subsidence and could be traced back to 0.83-0.84 Ma. The sea-level high stands and the age of the first one recorded above was different from other cores in eastern China, this was caused by the lack of absolute age control and the differences in paleotopography during this period. This study reconstructs sedimentary evolution, determines the transgression and its age, establishes the chronology since the Late Pliocene, and provides a scientific framework for further paleoenvironmental and tectonic studies. The results of this study highlight the important role that local tectonics and global sea level play in the sedimentary evolution and transgressions that have occurred in the western Subei Basin.

Spatio-temporal variability of phytoplankton assemblages and its controlling factors in spring and summer in the Subei Shoal of Yellow Sea, China

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea.In the present study,the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea.Phytoplankton species composition and abundance data were accomplished by Utermohl method.Diatoms represented the greatest cellular abundance during the study period.In spring,the phytoplankton cell abundance ranged from 1.59×10^3 to 269.78×10^3 cell/L with an average of 41.80×10^3 cell/L,and Skeletonema sp.and Paralia sulcata was the most dominant species.In summer,the average phytoplankton cell abundance was 72.59×10^3 cell/L with the range of 1.78×10^3 to 574.96×10^3 cell/L,and the main dominant species was Pseudo-nitzschia pungens,Skeletonema sp.,Dactyliosolen fragilissima and Chaetoceros curvisetus.The results of a redundancy analysis(RDA)showed that turbidity,temperature,salinity,pH,dissolved oxygen(DO),the ratio of dissolved inorganic nitrogen to silicate and SiO4-Si(DIN/SiO4-Si)were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.

Estimation of the amount of erosion at unconformities in the last stage of the Eocene Sanduo period in the Subei Basin,China

Strata erosion is a widespread phenomenon in sedimentary basins. The generation, migration, and accumulation of hydrocarbon is influenced by the scale of erosion, so estimating the amount of erosion is essential in the analysis of oil and gas bearing basins. According to the geological features in the Subei Basin and the actual data, using the integrated method, we estimated the level of erosion at the unconformities caused by the Sanduo event. By using the mudstone interval transit time method and the vitrinite reflectance method on data from typical wells, it can be concluded that the Gaoyou, Jinhu, and Hongze depressions suffered strong strata erosion from the late Eocene to Oligocene, and the total strata erosion thickness was 300–1,100 m. Different tectonic units in the same depression have extremely uneven erosion intensity: the low convex regions have the maximum erosion thickness, amounting to 800–1,100 m; the slope regions have an erosion thickness of generally 600–800 m; the erosion thickness of the slope-hollow transition zone is 300–500 m. For the whole basin, we used the strata thickness trend analysis method combined with the interval transit time and vitrinite reflectance methods to estimate the erosion thickness in the Sanduo period. The results show that the most severe erosion of the Sanduo event in the Subei Basin is between 1,000 m to 1,200 m, mainly located in depressions around the Jianhu Uplift; the deep hollow area has the least erosion, generally about 300–600 m, and the erosion in the slope area is about 600–900 m. Compared with the northern part, the southern part has relatively little erosion. It is also proved that the Sanduo movement has heterogeneous intensity, and the western region has greater intensity than the eastern region.

Exploration Strategies for Complex Fault Block Reservoirs in the Subei Basin

The geological background of the Subei basin is that of small relief subsidence, low geothermal gradient, multi-sedimentary hiatuses, intense reconstruction of the basin, frequent magmatic activity, and a unique combination of source rock and reservoir. This geological background resulted in characteristics such as many small fault blocks, multiple oil-bearing formations, scattered oil distribution, mini- to small-sized reservoirs, and difficulties in exploration. Aimed at such characteristics, an effective exploration strategy was adopted, and the oil reserves, production and economic benefits of the Jiangsu oilfield were significantly increased. This exploration strategy included understanding the hydrocarbon generation mechanism of source rocks, progressive evaluation of oil resources, comprehensive research on the faulted systems, the distribution of oil reservoirs and their controlling factors. The techniques used included integration of acquisition, processing and interpretation with 3-D seismics as the core technology, trap description and evaluation, directional drilling and cluster drilling, integration of cuttings logging, gas chromatographic logging and geochemical logging, and integration of early reservoir description and progressive exploration and development. This strategy could be guidance for other complex fault blocks.

Paleoclimatic and provenance implications of magnetic parameters from the Miocene sediments in the Subei Basin

Thick sediments from foreland basins usually provide valuable information for understanding the relationships between mountain building,rock denudation,and sediment deposition.In this paper,we report environmental magnetic measurements performed on the Miocene sediments in the Subei Basin,northeastern Tibetan Plateau.Our results show two different patterns.First,the bulk susceptibility and SIRM,ARM,and HIRM mainly reflect the absolute-concentration of magnetic minerals;all have increased remarkably since 13.7 Ma,related to provenance change rather than climate change.Second,the ratios of IRM100mT/SIRM,IRM100mT/IRM30mT,and IRM100mT/IRM60mT,together with the redness and S ratio,reflect the relative-concentration of hematite,being climate-dependent.Their vertical changes correlate in general with the long-term Miocene climatic records of marine oxygen isotope variations,marked by the existence of higher ratios between 17 and 14 Ma.This may imply that global climate change,rather than uplift of the Tibetan Plateau,played a dominant role in the long-term climatic evolution of the Subei area from the early to middle Miocene.

Impact of climatic change on sea surface temperature variation in Subei coastal waters,East China

Sea surface temperature （SST） variation in the Subei coastal waters, East China, which is important for the ecological environment of the Yellow Sea where Enteromorphaprolifera blooms frequently, is affected by the East Asian winter monsoon （EAWM）, El Nifio-Southem Oscillation （ENSO）, and Pacific Decadal Oscillation （PDO）. In this study, correlations between climatic events and SST anomalies （SSTA） around the Subei （North Jiangsu Province, East China） Coast from 1981-2012 are analyzed, using empirical orthogonal function （EOF） and correlation analyses. First, a key region was determined by EOF analysis to represent the Subei coastal waters. Then, coherency analyses were performed on this key region. According to the correlation analysis, the EAWM index has a positive correlation with the spring and summer SSTA of the key region. Furthermore, the Nifio3.4 index is negatively correlated with the spring and summer SSTA of the key region 1 year ahead, and the PDO has significant negative coherency with spring SSTA and negative coherency with summer SSTA in the key region 1 year ahead. Overall, PDO exhibits the most significant impact on SSTA of the key region. In the key region, all these factors are correlated more significantly with SSTA in spring than in summer. This suggests that outbreaks ofEnteromorpha prolifera in the Yellow Sea are affected by global climatic changes, especially the PDO.

Radium-traced nutrient outwelling from the Subei Shoal to the Yellow Sea:Fluxes and environmental implication

The Subei Shoal is the largest sandy ridge in the southern Yellow Sea and is important source for nutrient loading to the sea.Here,the nutrient fluxes in the Subei Shoal associated with eddy diffusion and submarine groundwater discharge(SGD)were assessed to understand their impacts on the nutrient budget in the Yellow Sea.Based on the analysis of 223 Ra and 224 Ra in the field observation,the offshore eddy diffusivity mixing coefficient and SGD were estimated to be 2.3×10^(8)cm^(2)/s and 2.6×10^(9)m^(3)/d(16 cm/d),respectively,in the Subei Shoal.Combined the significant offshore decreasing gradients of nutrient in seawater of the Subei Shoal,the spatially integrated nutrient outwelling fluxes to the Yellow Sea were 262-1465μmol/(m^(2)·d)for DIN,5.2-21μmol/(m^(2)·d)for DIP and711-913μmol/(m^(2)·d)for DSi.Compared to the riverine input,atmospheric deposition and mariculture,nutrient outwelling from the Subei Shoal might play an important role in nutrient budget of the Yellow Sea.These nutrient fluxes could provide 4.1%-23%N and 1.3%-5.3%P requirements for the primary productivity,and the deviated DIN/DIP ratios have the potential to affect the growth of phytoplankton in the marine ecosystem of the Yellow Sea.

The current situations of green macroalgae and micro-propagules in Pyropia aquaculture of the Subei Shoal in spring of 2013

To discover the distribution of green algal micro-propagules in the Subei Shoal and clarify the growth of green macroalgae attached on Pyropia aquaculture rafts,an integrated investigation in Pyropia aquaculture area and one cruise in the coastal area of the Subei Shoal were carried out from March to May in 2013.The results showed that green algal micro-propagules were discovered in seawater and sediment during March to May.The average quantity of micro-propagules was 267 ind./L in surface seawater and 43 ind./g in sediment.The biomass of attached green macroalgae increased in Pyropia aquaculture from March to May.Three species,including Ulva prolifera,Ulva linza and Blidingia sp.were found in Pyropia aquaculture rafts.The dominant specie was Blidingia sp.and the second was U.prolifera in spring.This study indicated that the micro-propagules and macroalgae were existed in the coastal area of the Subei Shoal at the early stage of green tide.This was the key point to the governance of green tide in China.

Analysis on Vegetation Succession Model and Process under Groundwater Exploitation in Subei Lake Watershed

[Objective] The study aimed to analyze vegetation succession process under groundwater mining conditions in Subei Lake watershed. [ Method] A succession model for vegetation and burial depth of groundwater level was constructed based on field survey, and it was used to pre- dict the vegetation succession rules and process according to the changes in burial depth of groundwater level in Subei Lake watershed under groundwater exploitation. [ Result~ In Subei Lake watershed, aquatic vegetation was most closely related to burial depth of groundwater level, fol- lowed by mesophytic vegetation, while psammophilous and xerophytic vegetation did not have obvious relation with burial depth of groundwater lev- el. When burial depth of groundwater level was small, dominant plants grew well, but they grew worse or died with the increase in burial depth of groundwater level. As the groundwater level fell constantly, burial depth of groundwater level went up, and vegetation succession would occur grad- ually from aquatic vegetation to mesophytic and xerophytic vegetation, from Carex L. and Iris ensata Thunb shoaly land to Achnatherum splendens shoaly lands, from Salix psammophila shrubs to Artemisia desterorum Spreng and Caragana korshinskii shrubs, and from Populus simonii to Salix matsudana. [Condusion] The research could provide scientific references for studying the relationship between groundwater resources and ecological environment in Subei Lake basin.

Evaluation on Ecological Vulnerability of the Vegetation in the Subei Lake Watershed Based on Analytic Hierarchy Process

[ Objective] The research aimed to evaluate ecological vulnerability of the vegetation in the Subei Lake watershed based on analytic hierarchy process （AHP）. [ Method] From actual situation of the vegetation ecology in the Subei Lake watershed, by the established evaluation index system of vegetation ecology, based on AHP, indicator weight at each layer was determined. Comprehensive index method was used to calculate ecological fragility degree of the vegetation in each evaluation unit to evaluate ecological vulnerability of the vegetation. [ Result] Ecological vulnera- bility of the vegetation was divided into four levels, such as extremely fragile, highly fragile, moderately fragile and lowly fragile in the Subei Lake watershed. The extremely fragile area, where buried depth of the groundwater level was generally less than 1.0 meter, distributed in beach zones near the Subei Lake, and its relationship between vegetation and groundwater was close. The lowly fragile areas scattered in the ridge zone around the Subei Lake watershed, where buried depth of the groundwater level was 10.0 -40.0 meters, and their relationship between vegetation growth and groundwater depth was not obvious. Buried depth of groundwater had the most sensitive influence on vegetation ecology, and it was the key factor between utilization of groundwater resources and eco-environment protection in the study area. E Conclusion] The researches provided scientific evidence for regional eco-environment protection, rational development and utilization of water resources, and coordinated development of economy and society.

加权断层泥比率法(WSGR)定量判别断层封闭性——以苏北盆地高邮凹陷永安地区为例

断层封闭性评价是断块圈闭成藏条件分析的重要内容,在改进断层泥比率法基础上,提出了一种新的断层封闭性评价方法——加权断层泥比率法(WSGR)。首先,通过不同的地质模型开展断层泥比率法计算参数及影响因素分析,明确了断层断距、泥质含量及泥岩分布特征是泥岩涂抹的重要影响因素;并认为断层断距范围内,滑过目标位置的对置盘所有泥质含量都具有涂抹贡献,但不同点的涂抹贡献不同,距离目标位置越近泥质含量越高的对置盘泥岩点,其涂抹贡献越大。为此引入了一个新的表征参数——距离系数,定义为断层断距与各泥岩点到目标位置距离的差与断层断距的比值,来表征泥岩分布对泥岩涂抹的影响作用;在此基础上,构建了加权断层泥比率计算方法,定义为各点的泥质含量与距离系数的乘积之和再与距离系数之和的比值。利用加权断层泥比率法对苏北盆地高邮凹陷上含油气系统已知的油水层进行封闭性验证,认为当加权断层泥比率值大于0.6时,断层具有较好的封闭性,从而确定了该方法的封闭性判别标准。在高邮凹陷永安等地区始新统戴南组断层封闭性评价中取得了较好应用效果。

陆相页岩油储层可动油含量测井评价方法——以苏北盆地古近系阜宁组二段页岩油为例

近年来中国东部陆相盆地页岩油勘探开发取得重大进展,但制约页岩油产能评价的关键因素是油可动性。研究苏北盆地页岩油提出了二维核磁共振法和常规测井法2种测井评价页岩可动油含量的方法。建立了二维核磁共振测量纵向弛豫时间(T1)-横向弛豫时间(T2)可动油识别图版,评价吸附油及束缚水等流体类型,通过游离烃含量(S1)与沉积环境、沉积构造的关系及测井响应的关联性,分析常规测井电阻率及声波时差对游离烃含量、有机质含量响应灵敏度,建立了游离烃含量测井定量评价模型。提出了测井资料评价游离烃含量的方法,计算可动油饱和度及含油量。咸化环境和纹层状构造有利于有机质成烃和运移,游离烃含量高。

苏北盆地古近系阜宁组二段页岩油储集空间特征及甜点段评价——以溱潼凹陷QY1井为例

苏北盆地古近系阜宁组二段是常规油重点产层,同时也是中国东部陆相页岩油勘探开发的优选层位。对溱潼凹陷QY1井岩心样品进行分析测试表明,该套页岩具有低有机质丰度、较低镜质体反射率(R_(o))、矿物组分均衡及孔隙网络复杂的特点;运用岩石学及地球化学方法等对该页岩油储层的岩相特征、储集空间特征、含油性与可动性、脆性指数与可压性特征等进行研究,指明了生产甜点段。阜二段是一套混积页岩纹层型储层,矿物组成以黏土、长英质和碳酸盐矿物为主,有机碳含量平均值为1.32%,R_(o)为0.9%~1.1%;平均孔隙度中下部为4%,上部为2.2%。根据“有机质丰度+构造特征+岩性”将阜二段页岩划分为6种岩相,其储集性具有明显差异,纹层发育特征的差异是导致不同岩相具有不同储集空间特征的重要原因。除低有机质纹层/层状灰云质页岩外,其他岩相都具有较好的含油性;高有机质层状灰质页岩的有机碳含量最高。纹层数量与油气可动性具有较好的对应性,从中有机质纹层状含灰云页岩到高有机质块状泥岩,平均含油饱和度指数从202.62 mg/g降至77.83 mg/g。高有机质块状泥岩由于存在大量塑性矿物,造缝效果是6种岩相中最差的。中有机质纹层状含灰云页岩是最优岩相,中有机质层状含灰云页岩和中有机质纹层/层状灰云质页岩略差,但也可以作为优势岩相成为勘探开发的重点。根据优势岩相在纵向上的分布,优选阜二段Ⅰ亚段③—⑤小层和Ⅱ亚段②—④小层为该区地质甜点段。

苏北盆地古近系阜宁组二段页岩油储层岩石力学特征及其控制因素

为查明苏北盆地页岩油储层可压性特征及压后孔、缝变化规律,以古近系阜宁组二段(阜二段)为研究对象,对岩石力学特征、压裂效果及其影响因素进行研究。用计算机高分辨断层扫描成像技术(多尺度CT扫描)对岩样进行三维重构,获取孔、缝结构参数;开展地层围压下三轴力学实验,获取岩石力学参数;将压裂后的岩样按相同位置和方向再次进行多尺度CT扫描,获取压裂后三维孔、缝结构图像。根据应力-应变曲线特征,将本区页岩划分为3种类型。①1型页岩,为破裂曲线波浪下降,压后形成复杂网状缝页岩。②2型页岩,为破裂曲线类型多样,具波浪下降和垂直下降形状,压后缝网较发育的页岩。③3型页岩,为破裂曲线垂直下降,破裂后整体较完整,压后多形成纵向劈裂缝、缝网不发育的页岩。这3种类型页岩压后孔隙变化特征是:1型和2型页岩直径10~50μm孔隙占比减少,直径50~100μm孔隙增多,直径300μm以上孔隙孔容贡献增大;3型页岩压裂前、后孔径分布及孔容贡献变化不明显。研究表明,抗压强度与弹性模量、剪切模量具有正相关关系,与泊松比具有V型曲线关系;碳酸盐和黏土矿物含量是控制本区页岩力学性质的主要因素,石英和有机碳含量为次要因素。孔隙度及纹层发育特征是页岩储层可压性特征的重要影响因素。

苏北盆地溱潼凹陷阜宁组二段页岩油测井评价研究

如何利用常规测井资料对储层含油性、储集性及可压性进行有效评价,是苏北页岩油规模化开发亟需解决的生产难题。利用常规测井资料与岩心实验资料,采用最优化、拟合、正反演数值模拟等数学手段,建立起总有机碳含量、有效孔隙度、层理缝密度、矿物组分含量等参数的计算模型,对页岩沉积构造和岩相进行分类研究。研究表明:溱潼凹陷阜宁组二段(以下简称阜二段)泥页岩以富有机质层状或纹层状泥岩、富有机质块状泥岩为主,有利岩相为富有机质层状或纹层状泥岩,有利岩相纵向上与非有利岩相交互出现。采用文中所导出的模型识别的“甜点”层段与采用特殊测井分析的层段位置具有良好的一致性,且现场应用效果良好。该方法和技术已应用于苏北盆地页岩油储层地质工程“甜点”段的选定工作,对苏北页岩油效益开发具有重要意义。

高邮凹陷花庄地区页岩油二维核磁测井评价应用

苏北盆地高邮凹陷古近系阜宁组二段泥页岩具有孔隙结构复杂、层理发育、非均质性强的特点,应用常规测井系列难以准确评价孔隙及流体类型,二维核磁共振测井在流体识别方面具有独特优势。应用“盲源分离”信号处理技术进行数据聚类分析,通过花庄地区流体分区模型识别出地层中不同赋存状态的流体及含量。研究结果表明:二维核磁测井提高了储层流体评价精度,提供较为可靠的总孔隙度、有效孔隙度、含油饱和度、可动油含量等参数,通过与岩心实验分析对比,有效孔隙度平均绝对误差为0.4%,含油饱和度平均绝对误差为7.3%。通过阜宁组二段泥页岩主要岩性中流体性质分析,表明长英质灰云质混积页岩在物性、含油性、可动性方面最优,是页岩油优质“甜点”层。花庄地区应用二维核磁测井能够有效地解决页岩油孔隙度、饱和度评价的难题,也能为页岩油“甜点”优选、储层产能预测提供参考。

苏北盆地黄桥地区盐城组氦气成藏地质条件及富集规律

苏北盆地黄桥地区新近系盐城组天然气中He含量介于1.05%~1.40%,普遍高于工业品位,为壳—幔复合型氦气资源。目前,对于这种来源的氦气富集主控因素以及勘探目标评价的研究较为薄弱,为此,系统剖析了黄桥地区典型富氦气藏氦气成因、来源及圈闭特征,重点分析了幔源断裂对富氦气藏输导作用、盐城组圈闭条件的影响,提出了黄桥地区盐城组富氦气藏富集模式。结果表明:(1)黄桥地区南新街深大断裂在盐城组沉积时期持续活动,导致幔源物质上涌,伴随着火山活动及CO_(2)、N_(2)以及氦气沿断裂运移至浅层;(2)黄桥地区盐城组埋深为370~400 m,盐城组底部砂岩厚度约为40 m,上覆10~40 m泥岩,储盖组合有利,富氦气层由东往西尖灭;(3)黄桥地区盐城组整体为单斜构造,盐城组底部界面与下伏地层呈角度不整合,通过地震标定及解释,刻画出了富氦气层岩性—地层复合圈闭面积。黄桥地区盐城组富氦气藏具有断裂沟通地幔输导、砂岩储集、泥岩作为盖层、岩性—地层复合圈闭富集等特征,该认识对黄桥地区氦气有利目标评价具有重要意义。

Eutrophication of Jiangsu Coastal Water and Its Role in the Formation of Green Tide

Since 2007,the large-scale green tide caused by Ulva prolifera(U.prolifera)have occurred as a recurrent phenomenon in the southern Yellow Sea of China.Field surveys and satellite remote sensing showed that the small scattered patches of green tide algae were first observed along the Porphyra agriculture area of the Subei Shoal in late April.In this study,we attempted to identify the role of eutrophication in the origin of the green tide in the Subei Shoal and its adjacent area.Subei Shoal and its adjacent area are characterized by rich nutrients,especially NO_(3)^(-)-N,NH_(4)^(+)-N,PO_(4)^(3-)-P,and other bioavailable components(such as urea-N and amino acids).In the spring of 2017,the average concentrations of NO_(3)^(-)-N were 19.01±11.01μmolL^(-1),accounting for 86.68%of the dis-solved inorganic nitrogen(DIN).In addition,the average concentration of NH4^(+)-N was 2.51±1.60μmolL^(-1).PO_(4)^(3-)-P had an average concentration of 0.14±0.13μmolL-1.The average concentrations of urea-N and total hydrolyzed amino acids(THAA)were 1.73±1.36μmolL^(-1)and 1.33±0.80μmolL^(-1),respectively.Rich nutritive substances play a key role in the rapid production of U.prolifera and make the Jiangsu coastal water an incubator for green tide.

苏北盆地高邮凹陷花页1井古近系阜宁组裂缝脉体流体演化及其对页岩油充注过程的指示意义

苏北盆地页岩油勘探开发取得重大突破。高邮凹陷花页1井岩心观察发现,古近系阜宁组二段富有机质页岩中天然裂缝发育,脉体内保存了大量页岩油气流体活动迁移的信息。以阜二段页岩裂缝充填的方解石脉体为研究对象,综合运用矿物学、元素地球化学、地质年代学以及地质流体技术,聚焦页岩裂缝脉体的古流体来源、脉体形成时间以及流体包裹体特征开展深入研究,提出页岩含油层埋藏、抬升剥蚀过程中古温度条件与对应地质时间。阜二段页岩裂缝主要产状类型为层理缝、滑脱缝、剪切缝、收缩缝和张性缝,裂缝内主要充填一期纤维状方解石脉体,方解石脉体表现为偏还原环境热液流体的来源;始新世中期阜二段裂缝脉体捕获原生绿色荧光油包裹体、始新世晚期捕获次生蓝色荧光油包裹体和第四纪晚期捕获次生绿色荧光油包裹体,分别指示了富有机质页岩主要存在三期页岩油的充注过程。页岩油的充注主要在页岩最大埋深时期形成,三垛构造运动对于该地区页岩油的调整运移具有重要作用。