共查询到19条相似文献，搜索用时 812 毫秒
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烃类气体是海底渗漏烃的重要组分之一。它们在海底沉积物中主要以游离态和束缚态形式存在。测量海底沉积物烃类气体组成的方法有顶空气法、酸解烃法和热释烃法等。顶空气测量的是在海底沉积物中以游离态存在的烃类气体,酸解烃测定的是吸附在颗粒表面或存在内部包裹体中的束缚烃类气体,热释烃测定的是海底沉积物中被硅铝酸盐所吸附的束缚烃类气体。海底沉积物地球化学异常识别方法包括图解法和计算法等多种方法。海底沉积物地球化学异常成因主要包括有生物成因、热成因和混合成因等。利用烃类气体含量、组合及比值,结合同位素组成特征可以解释地球化学异常成因。 相似文献
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神狐海域天然气水合物的特征及其气源 总被引：1，自引：0，他引：1
我国天然气水合物首钻的钻探结果显示,南海北部陆坡神狐海域的天然气水合物呈分散浸染状分布在以粗粉砂、中粉砂、细粉砂和极细粉砂为主要组分的松散沉积物中。沉积物顶空气组成分析显示,神狐钻探区沉积物中的游离气体主要是烃类气体,另外也有微量的CO2,其中,甲烷含量界于62.11%~99.91%之间,平均含量达到了98.04%。而天然气水合物的气体同位素组成显示,神狐海域形成天然气水合物的烃类气体主要是微生物通过CO2还原的形式生成。在此基础上,进一步分析了神狐海域研究区上中新统上部和上新统微生物成因甲烷的生产力,认为神狐海域具备良好的适合微生物成因甲烷大量生成的地质条件。 相似文献
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我国渤海—东海表层沉积物中吸附气态烃的特征 总被引：2，自引：1，他引：2
崔秀荣 《海洋地质与第四纪地质》1983,(1)
吸附气态烃系指沉积物中有机物质转化为烃类气体被矿物颗粒吸附的甲烷及其同系物.吸附气态烃的研究,引起了国内外学者的极大兴趣,这是因为:气态烃类有良好的迁移性能,从地下深处或油气藏向上扩散运移时,导致了近地表沉积物中烃类浓度的增高和气体组合的改变.根据高对比度的烃类异常,可以追索和指示油气藏、评价生油岩、研究油气的分布规律.近年来,我国学者利用吸附气态烃研究现代沉积物的地球化学特征及其与油气藏的关系,取得了丰富的资料和可喜的成果.作者从1974年开始,对渤海、黄海及东海表层沉积物中的吸附气态烃进行了研究,大量的实验资料表明,吸附气态烃在表层沉积物中广泛发育,绝对含量之高可与内陆还原环境下的沉积物或生油岩相媲美,并有相同的气体组合.一、吸附气态烃的分布特征 相似文献
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南极布兰斯菲尔德海峡表层沉积物的酸解烃 总被引：1，自引：0，他引：1
本文研究了南极布兰斯菲尔德海峡表层沉积物的酸解烃分布特征，并佐以热释汞和蚀变碳酸盐的分析。从酸解烃中甲烷含量的低值和Ｃ１／（Ｃ２＋Ｃ３）比值，以及乙烯的存在等判断，布兰斯菲尔德海峡沉积物的烃类气体来自于生物成因。 相似文献
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利用海底烃类气体渗漏实验模拟装置对海底烃类气体渗漏过程进行了实验模拟。通过10个采样口样品采集和分析测试,探讨了各采样口在渗漏过程中烃类气体含量和分子组成变化。各采样口烃类气体含量和分子组成随时间具有明显阶段变化,总体显示了两阶段渗漏特征:第1渗漏阶段从7月13日到8月5日,第2渗漏阶段从8月6日到9月25日。根据各采样口烃类气体在两阶段渗漏强度可分为3类:第1类包括S1、S2、S5、S7和S8,表现为在第1阶段和第2阶段渗漏强度均不高,属于微渗漏类型;第2类包括S3、S4和S9,表现为在第1阶段渗漏强度低,属于微渗漏类型,在第2阶段渗漏强度高,属于宏渗漏类型;第3类包括S6和S10,表现为在第1阶段和第2阶段均属于宏渗漏类型。烃类气体渗漏主要受实验柱体内各种界面和沉积物粒度等因素控制,而且不同采样口渗漏烃类气体含量变化的控制因素也不尽相同。模拟结果为研究海底烃类气体渗漏过程中,断裂构造、地层不整合界面、岩性差异界面,以及沉积物粒度变化等对海底烃类气体渗漏控制机理提供了实验依据。 相似文献
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自然界中赋存的气体水合物在海底沉积物是处于半固结状态,具有储存大量的气体和水的潜能。当水合物的平衡条件被打破时,能释放出气体和水。因此,水合物能给巨大的沉积物搬运提供潜在的形成机制。在海底低水温和正常静水压力条件下,大部分陆坡和所有海隆、深海平原在靠近海底沉积物的孔隙不处在饱和或近饱和状态下,烃类气体将形成水合物。水合物的气体既可能是原地微生物成因气,也可能是来自较深部沉积物的热解气。稳定水合物沉积物的平衡条件可能遭到破坏,例如由连续沉积或者海平面下降所引起,其中任何一种情况出现使部分固体气－水混合物开始分解。释放出气体和水的体积超过水合物自身的体积,如果大量水合物分解,那么其内部压力能猛烈地骤增,原来部分稳定的沉积物转化为富含气体和富含水的低密度泥岩。当内部压力由于气体压缩或者浮力作用变得非常大时,其上覆沉积物隆起甚至破裂,而非致密的气侵泥岸可以向上运移。与水合物有关非常大时,其上覆沉积物隆起甚至破裂,而非致密的气侵泥岸可以向上运移。与水合物有关的这些现象可以引起泥底辟、泥火山、泥滑坡或浊流,这取决于沉积物的结构和海底地形。 相似文献
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The presence of large amounts of gas and/or liquid hydrocarbon seepage in near surface sediments can produce distinct features
including an irregular topography (on several scales, ranging from meters to kilometers); seismically transparent/chaotic
sediments; oil staining; gas plumes; sediments containing elevated concentrations of extractable organic matter, organic carbon,
and calcium carbonate; associated brine seepage and anoxic conditions; extensive bacterial mats; hydrate formation and decomposition;
and dense chemoautotrophic communities. Although no single characteristic is always uniquely associated with seepage, the
co-occurrence of several of these features is strongly suggestive of an area being exposed to non-indigenous upward migrating
hydrocarbons. 相似文献
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Pockmarks are observed worldwide along the continental margins and are inferred to be indicators of fluid expulsion. In the present study, we have analysed multibeam bathymetry and 2D/3D seismic data from the south-western Barents Sea, in relation to gas hydrate stability field and sediment type, to examine pockmark genesis. Seismic attributes of the sediments at and beneath the seafloor have been analysed to study the factors related to pockmark formation. The seabed depths in the study area are just outside the methane hydrate stability field, but the presence of higher order hydrocarbon gases such as ethane and/or propane in the expelled fluids may cause localised gas hydrate formation. The selective occurrence of pockmarks in regions of specific seabed sediment types indicates that their formation is more closely related to the type of seabed sediment than the source path of fluid venting such as faults. The presence of high acoustic backscatter amplitudes at the centre of the pockmarks indicates harder/coarser sediments, likely linked to removal of soft material. The pockmarks show high seismic reflection amplitudes along their fringes indicating deposition of carbonates precipitated from upwelling fluids. High seismic amplitude gas anomalies underlying the region away from the pockmarks indicate active fluid flow from hydrocarbon source rocks beneath, which is blocked by overlying less permeable formations. In areas of consolidated sediments, the upward flow is limited to open fault locations, while soft sediment areas allow diffused flow of fluids and hence formation of pockmarks over a wider region, through removal of fine-grained material. 相似文献
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以曹妃甸邻近海域为研究区,利用生物标志化合物地球化学参数分析了表层沉积物中石油烃类的主要组成和分布特征,探讨了石油烃污染物的来源。结果表明,曹妃甸邻近海域表层沉积物中正构烷烃为混源,且陆源贡献小于海洋源。地质构型藿烷、甾烷在甾萜类化合物中为优势组分,且萜甾烷参数显示了有机质成熟度较高。饱和烃的多种地球化学参数显示了该区域表层沉积物可能受到成熟度较高的石油烃输入及其后期微生物降解的影响。该研究将为曹妃甸近岸沉积物输移研究提供基础资料,进而为曹妃甸围填海工程的科学决策提供相关科学数据。 相似文献
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1994～1995年间在东海外陆架获取370个柱状样,每个样长约为2～4m.对其底部沉积物作了磁性测试,发现局部地区存在SIRM异常高现象.由磁参数推断导致SIRM异常的矿物为硫复铁矿.将磁性异常地区沉积物作矿物磁选,对磁选所得矿物做扫描电镜、电子探针和能谱、X衍射及穆斯堡尔谱测试,证实了次生硫复铁矿的存在.结合本区新生代油气构造圈闭和残留沉积物可溶铁Fe3+/Fe2+比值异常的分布,用油气渗漏解释了SIRM异常及硫复铁矿的成因,从而认为SIRM异常对深部油气藏具有指示意义. 相似文献
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东海西北部陆架表层沉积物重矿物组合及其沉积环境指示 总被引：3，自引：0，他引：3
研究了东海陆架360个表层沉积物的碎屑矿物和粒度组成,利用R型聚类方法提取稳定重矿物和重矿物分异指数作为矿物分布规律的指示因子;根据快速聚类结果将重矿物组成分为3个区:东海陆架海侵体系域晚期残留砂体区、高位体系域晚期长江水下前三角洲和浙闽沿岸流泥质沉积区、高位体系域扬子浅滩沉积区。结合粒度参数和特征矿物分布、沉积物14C年龄对各区沉积环境进行讨论,确定陆架残留沉积和改造沉积的成因、长江水下三角洲和浙闽沿岸流泥质区的范围,以及对应不同海侵层序的矿物分异特征和物质"源-汇"关系。聚类分析虽能够指示同一物源碎屑矿物分布与沉积动力关系,但物源不同,聚类结果可能误导沉积环境分析。扬子浅滩表层砂体是在距今6~4和3~2 ka 的两个潮流沉积发育期形成的多期改造沙波沉积。 相似文献
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Fine-grained sediments from the Late Triassic Yanchang Fm. in the Ordos Basin (central China) were studied by core analysis and geophysical logging. Part of the mudstones in this formation are stratified, part of them are unstratified; the various mudstones can be subdivided into eight types on the basis of their structures and textures. They represent a variety of environments, ranging from delta fronts and subaqueous fans to deep-water environments. Part of the sediments were reworked and became eventually deposited from subaqueous gravity flows, such as mud flows, turbidity currents and hyperpycnal flows that easily developed on the clay-rich deltaic slopes. The sediments deposited by such gravity flows show abundant soft-sediment deformation structures. Understanding of such structures and recognition of fine-grained sediments as gravity-flow deposits is significant for the exploration of potential hydrocarbon occurrences. Because fine-grained deposits become increasingly important for hydrocarbon exploration, and because the sediments in the lacustrine Yanchang Formation were deposited by exactly the same processes that play a role in the accumulation of deltaic and prodeltaic fine-grained sediments, the sedimentological analysis provided here is not only important for the understanding of deep lacustrine sediments like the Yanchang Formation, but also for a better insight into the accumulation of fine-grained prodeltaic deep-marine sediments and their potential as hydrocarbon source rocks and reservoir rocks. 相似文献
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Petroleum hydrocarbon concentrations (PHC) of surface sediments along the Chennai coast, India, were measured by UV-Fluorescence (UVF) Spectroscopy and the results are expressed in terms of Chrysene equivalents. The concentration of PHC in sediment varies widely (from 1.88 ppm to 39.76 ppm) as compared to the baseline (1.88 ppm) with higher values obtained in the northern part of the study area. The highest magnetic susceptibility (96.8 × 10−8 m3kg−1) value was determined from the Chennai harbour area. The magnetic parameters show that the Chennai coastal sediments are dominated by ferrimagnetic minerals. The positive correlation (r2 = 0.86; p < 0.05) between petroleum hydrocarbon concentrations and magnetic susceptibility suggests that the magnetic minerals and petroleum hydrocarbons along the Chennai coast are derived from the same sources. Factor analysis shows that the magnetic concentration dependent parameters (χ, χARM and SIRM) covary with the petroleum hydrocarbon concentration, suggesting that large amounts of magnetic minerals originate from anthropogenic activities. It is evident that using magnetic measurements may be considered a simple, rapid, cheap and non-destructive method to determine petroleum hydrocarbon concentrations in coastal sediments. Furthermore, this technique may be applied to petroleum exploration studies. Magnetic susceptibility measurements in sediments have been proposed as complementary or alternative means of exploration and assessment of hydrocarbon reservoirs. 相似文献
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东海陆架北部表层细粒级沉积物的级配及意义 总被引：3，自引：3，他引：3
本文依据东海陆架北部 2 3个表层沉积物样品的粒度分析资料 ,就东海陆架北部表层细粒级沉积物的级配及意义进行了研究。结果表明 ,研究区表层沉积物中细粒级部分以 <0 .0 16 mm为优势粒级 ,可占到总细粒级沉积物的 75 %以上。济州岛西南泥质区以细于 0 .0 0 8mm粒级的沉积物占据优势 ,长江口泥质区则以 <0 .0 16 mm粒级的沉积物为主 ,两泥质区细粒级沉积物的级配很不相同 相似文献