Paragenesis of fluids under evaporates in the Volga-Ural Basin     

《Marine and Petroleum Geology》2015

To unravel the mystery of the relationship between evaporates, Ca–Cl brines and accumulations of oil and N₂ in the basins of ancient cratons, their N₂, CH₄ and He concentration ratios, as well as the isotopic composition (δ¹⁵N, δ¹³C and ³He/⁴He) were compared within the Volga-Ural basin. The study allowed subsalt fluids from Volga-Ural Basin to divide into two genetic groups. The first one is found within the basin's platform area. It includes Ca–Cl brines, high-viscosity heavy oil, bitumen and N₂, which has concentrations higher than that of CH₄ and positive values of δ¹⁵N. The second one is tied to the edge of the platform, the Ural Foredeep and Peri-Caspian Depression. In this group, only the oil and gas reservoirs, which have more CH₄ than N₂, and possibly negative values of δ¹⁵N, were discovered. Interaction of gas components in compared fluids indicates great role of degassing in the formation of their composition. It is suggested that the fluids of the first group (N₂ > CH₄) is what remains, and the second group (N₂ < CH₄) is what is disappears from the rocks during their metamorphism and degassing.  相似文献   

白云石化作用及白云岩储层研究进展   总被引：1，自引：0，他引：1  

黄擎宇  刘伟  张艳秋  石书缘  王坤 《地球科学进展》2015,30(5):539-551

白云石化作用和白云岩储层一直都是碳酸盐岩研究中的重要领域。近年来,随着实验分析技术的进步以及油气勘探的深入,对白云岩的研究也取得了诸多进展:1数值模拟技术逐步应用到白云岩研究中,实现了白云石化模式研究由定性到定量的转变;2对微生物白云石化的研究不断加强,识别出了微生物相关白云石的特殊显微形貌特征并对其生物矿化机制进行了分析;3对已有白云石化模式的重新审视:包括对混合水白云石化的修正、对回流白云石化的扩展以及对构造—热液白云石化模式的丰富;4在白云石化与孔隙相关关系的研究中,突破了白云石化增孔的传统认识,逐步强调白云石化在孔隙保存方面的作用;5注重研究白云岩结构、成岩环境、原始相带以及白云岩形成之后的溶蚀改造等因素对白云岩储层发育的控制作用。在未来的研究中,应加强3个方面内容,一是对白云岩结构演化规律的定量研究,二是在成岩流体示踪方面要加强对新技术手段(如二元同位素、Mg同位素)的使用,同时注意借鉴成矿流体研究中的成熟技术和方法,三是要加强对深部白云岩储层形成和保存机制的探索。  相似文献   

三峡水库运行初期的泥沙淤积特点   总被引：3，自引：0，他引：3       下载免费PDF全文

李文杰  杨胜发  付旭辉  肖毅 《水科学进展》2015,26(5):676-685

针对三峡蓄水运行后的泥沙淤积问题,基于实测资料,采用输沙率法和断面法分析了三峡水库运行初期的泥沙淤积特点.结果表明:三峡水库2003—2013年泥沙淤积总量为15.31亿t,平均排沙比为24.5%,均较论证阶段降低;库区泥沙淤积主要分布在常年回水区的宽谷和弯道河段,宽谷段全断面发生淤积、弯道断面流速较小一侧淤积、峡谷无累积性淤积;常年库区近坝段泥沙淤积速度逐年减小,而上段泥沙淤积速度则呈增大趋势;淤积物粒径沿程分选不明显,常年回水区淤积物中值粒径多在0.01 mm以下.库区峡谷段深泓线无明显变化、尚未出现泥沙淤积三角洲、库尾泥沙淤积上延和尾水抬高不明显,据此初步推断峡谷河段存在富余挟沙力而成为局部侵蚀基准面,整个库区将无统一平衡比降的趋势.  相似文献   

庆阳-合水地区长8油层组沉积物源分析     

杨梦辉  刘广锋  童明均  杨伟伟 《地下水》2015,(2)

物源分析对砂岩储层的展布与分析预测具有重要的意义。通过对鄂尔多斯盆地西南缘庆阳-合水地区上三叠统延长组长8油层组的砂岩重矿物组合、轻矿物组合及砂岩岩屑组分的平面分布特征分析,判断了庆阳-合水地区的沉积物源方向。研究表明,庆阳-合水地区存在两大物源和古流沉积体系,即西南方向的庆阳沉积古流体系和南部方向的合水沉积古流体系;长82亚组沉积期以南部的沉积古流体系为主,而长81亚组沉积期以西南部的沉积古流体系为主;重矿物组合特征分析显示长81亚组沉积期合水区带混源现象明显。  相似文献   

小浪底水库淤积形态数值模拟          下载免费PDF全文

假冬冬  王远见  江恩惠  邵学军  张幸农 《水科学进展》2020,31(2):240-248

水库淤积形态是影响库容分布、水库排沙的一项重要因素。小浪底水库近坝段淤积泥沙粒径极细,具有流动性,针对其细颗粒泥沙淤积特点,揭示了水库细颗粒淤积物的流变特性与流型特征;通过引入水、淤积物、床面之间的界面受力分析,构建了细颗粒淤积物失稳流动描述模式,并与水沙输移模型相耦合,建立了考虑细颗粒淤积物流动特性的水库淤积形态模拟方法,在此基础上对小浪底水库淤积形态进行了验证分析。研究结果表明:低密度细颗粒淤积物为宾汉型流体,淤积平衡坡降较小,当其密度大于1.25 g/cm 3后,流动性快速减弱;考虑细颗粒淤积物流动特征的水库淤积形态模拟结果与实测结果吻合较好。研究成果可为水库淤积形态形成机理及其对水沙调控的响应研究提供技术支撑。  相似文献   

A method to estimate the longshore sediment transport at ebb-tidal deltas based on their volumetric growth: Application to the Guadiana (Spain–Portugal border)     

Erwan Garel  Alejandro López-Ruiz  Óscar Ferreira 《地球表面变化过程与地形》2019,44(13):2557-2569

Current techniques assessing longshore sediment transport rates have large uncertainties, pleading for the development of alternative and complementary approaches. The present study proposes a method to estimate the decadal average rate of longshore transport at modern ebb-tidal deltas based on a sediment budget analysis of the outer shoal growth. This transport is obtained as the balance of the other contributions to the shoal with the total sediment input rate obtained from an inverse application of the inlet reservoir model. The method is applied to the Guadiana ebb-tidal delta, yielding an average longshore sediment transport rate (~85 000 m3 year⁻¹) in good agreement with expectations for the region. It is exemplified that this decadal averaged rate can be used to improve longshore sediment transport expressions in order to study its variability over shorter time scales. At the Guadiana, the yearly longshore sediment transport from the improved formula ranges from ~25 000 m³ (westward) to ~245 000 m³ (eastward) and is related to the North Atlantic Oscillation index. Overall, the proposed method constitutes an alternative tool to constrain the average longshore sediment transport rate over decades in the vicinity of tidal inlets. It is applicable to ebb-tidal deltas where the outer shoal growth (from an early to a mature stage) is well documented by bathymetric maps, and where the main transport pathways towards the outer shoal can be specified. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.  相似文献   

Acoustic and petrophysical properties of mechanically compacted overconsolidated sands: Part 2 – Rock physics modelling and applications     

Sirikarn Narongsirikul  Nazmul Haque Mondol  Jens Jahren 《Geophysical Prospecting》2019,67(1):114-127

Part one of this paper reported results from experimental compaction measurements of unconsolidated natural sand samples with different mineralogical compositions and textures. The experimental setup was designed with several cycles of stress loading and unloading applied to the samples. The setup was aimed to simulate a stress condition where sediments underwent episodes of compaction, uplift and erosion. P-wave and S-wave velocities and corresponding petrophysical (porosity and density) properties were reported. In this second part of the paper, rock physics modelling utilizing existing rock physics models to evaluate the model validity for measured data from part one were presented. The results show that a friable sand model, which was established for normally compacted sediments is also capable of describing overconsolidated sediments. The velocity–porosity data plotted along the friable sand lines not only describe sorting deterioration, as has been traditionally explained by other studies, but also variations in pre-consolidation stress or degree of stress release. The deviation of the overconsolidated sands away from the normal compaction trend on the V_P/V_S and acoustic impedance space shows that various stress paths can be predicted on this domain when utilizing rock physics templates. Fluid saturation sensitivity is found to be lower in overconsolidated sands compared to normally consolidated sands. The sensitivity decreases with increasing pre-consolidation stress. This means detectability for four-dimensional fluid saturation changes can be affected if sediments were pre-stressed and unloaded. Well log data from the Barents Sea show similar patterns to the experimental sand data. The findings allow the development of better rock physics diagnostics of unloaded sediments, and the understanding of expected 4D seismic response during time-lapse seismic monitoring of uplifted basins. The studied outcomes also reveal an insight into the friable sand model that its diagnostic value is not only for describing sorting microtextures, but also pre-consolidation stress history. The outcome extends the model application for pre-consolidation stress estimation, for any unconsolidated sands experiencing similar unloading stress conditions to this study.  相似文献   

Methane Oxidation in the Water Column of Xiangxi Bay,Three Gorges Reservoir     

Dan Lei  Jia Liu  Junwei Zhang  Andreas Lorke  Shangbin Xiao  Yuchun Wang  Wei Wang  Ye Li 《洁净——土壤、空气、水》2019,47(9)

Four field campaigns are carried out to quantify the methane (CH₄) oxidation rate in Xiangxi Bay (XXB) of the Three Gorges Reservoir (TGR), China. The water depth of the sampling site varied from 13 to 30 m resulting from the water level fluctuation of the TGR. The CH₄ oxidation rates are measured in situ as the decline of dissolved CH₄ concentration versus time in incubated, and those rates. The CH₄ oxidation rates range from 1.18 × 10^?3 to 3.69 × 10^?3 µmol L^?1 h^?1, with higher values and stronger variation during summer. A static floating chamber method is used to measure CH₄ emitted to the atmosphere resulting in an annual mean flux of 4.79 µmol m^?2 h^?1. The CH₄ emission rate is significantly negatively correlated with the water level. The results show that a large fraction of CH₄ is consumed in the water column with a range of 28.97–55.90 µmol m^?2 h^?1, accounting for ≈69–98% of the total CH₄ input into the water column, and more than 90% is consumed outside the summer, when the water level is lowest. Water depth, which is dominated by water level of the TGR, is a potentially important driver for CH₄ oxidation and atmospheric emission in the tributary bay.  相似文献   

Phosphorus fractions and sorption dynamics in the sediments of two Ca-SO4 water reservoirs in the central Argentine Andes     

Jos&#; Gabriel Le&#;n  Fernando Luis Pedrozo  Pedro F&#;lix Temporetti 《国际泥沙研究》2017,32(3)

  相似文献   

2014年鲁甸M_S6.5地震前后地震活动性          下载免费PDF全文

侯金欣  王宝善 《地球物理学报》2017,60(4):1446-1456

2014年 8月3日在云南省鲁甸县发生M_S6.5地震，造成了巨大的人员伤亡和财产损失.关于鲁甸地震的起因，特别是鲁甸地震与溪洛渡水库之间的关系存在一些争议.分析中强地震前后地震活动性的变化可以为判断主震起源提供一定的依据.然而，由于鲁甸地震震中附近固定台站数目少、台站距离震中远及主震后尾波干扰等因素的影响，会造成地震目录的缺失，从而可能影响地震活动性的可靠分析.为了获得更加完备的地震目录，本文采用模板匹配方法对鲁甸地震前后小地震进行了搜索和识别.以台网目录中的541个事件作为模板，在主震之前33天到主震后5天的连续波形中识别出991个未在目录中列出的地震，使余震的完备震级从1.8降低到1.3.根据检测目录得到主震前33天内的b值为1.04±0.18，余震的b值在震后5天内由0.5左右逐渐上升至0.9附近并保持稳定；根据2009年到主震发生前的台网目录得到该区域的背景b值为0.93±0.04.即鲁甸地震前后区域地震活动b值均与背景b值接近，这与典型水库诱发的中强震具有的b值特征不相符.同时通过进一步分析台网目录，未发现溪洛渡水库蓄水前后研究区域内的地震活动性存在明显变化，这也与典型水库诱发地震区域的地震活动性特征不相符.综合以上结果，我们认为2014年鲁甸M_S6.5地震不具有典型水库诱发地震的特征.  相似文献