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利用地震剖面获取海水层温度、盐度、密度等物理参数成为地震海洋学研究的一个重要问题.本文提出了以CTD(Conductivity-Temperature-Depth)温盐深剖面仪观测资料为约束的波阻抗、温-盐结构反演方法.该方法包括两个步骤:首先把少量的CTD作为"约束井"进行地震数据的波阻抗反演;然后利用从CTD资料获得的研究海区的温-盐关系式,结合波阻抗数据反演得到温度和盐度剖面.通过合成数据的试算表明,基于少量的CTD资料控制,利用地震数据可以反演得到高分辨率的二维温度、盐度结构.基于地震数据的温-盐结构反演方法有望弥补传统物理海洋学观测方法的不足,为海洋学研究提供大量的基础数据,有广泛的应用前景. 相似文献
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通过地震海洋学联合调查航次，获得了同时采集的高分辨率多道地震数据与水文数据（XBT）联合调查数据.通过针对性处理获得了清晰的海洋水体反射地震剖面，捕捉到南海东北部次表层涡旋，证明了该调查方法的有效性.利用背景场约束反演方法得到海水的波阻抗、声速、密度、温度和盐度剖面，揭示了涡旋具有相对低速、高密、低温与高盐特征.处理和反演结果表明，在浅部和部分噪声较强和无约束反演区域，结果误差较大，可靠性较低.调查结果说明，获得较高信噪比的原始高分辨率地震资料采集技术方法、联合约束数据的获取、针对性的特殊处理方法和有效的反演方法是地震海洋学资料有效分析利用的重要保证. 相似文献
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利用地震数据反演海水的温盐分布是地震海洋学研究的一个重要方向.本文分析了采集于伊比利亚半岛西南缘海域的GOLR12低频地震数据和同步观测的XBT(eXpendable BathyThermograph)、CTD(Conductivity-Temperature-Depth)资料,将叠后约束波阻抗反演方法应用到海水温度、盐度剖面的计算当中,计算结果显示这种反演方法可以提供水平分辨率为6.25 m的温度和盐度资料,温度的精度约为0.16 ℃,可以为物理海洋学研究提供高横向分辨率的基础数据. 相似文献
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本文利用地震海洋学新的反演结果,对地中海涡旋的温度、密度、声速以及波阻抗等物理性质进行了详细的分析与讨论,特别对地中海涡旋的一些细结构、混合过程进行了相关描述.研究分析取得以下认识:(1)涡旋具有涡旋核心水与涡旋混合水双层结构,这种结构特征可以在温度图、声速图和波阻抗图中识别出来;(2)涡旋核心水并不是均匀的稳定结构,内部有微弱的混合作用;(3)在涡旋上部以及周围边缘区域,海水的混合比较复杂;在涡旋下部边缘区域,除了有小尺度的盐指混合,内波也是非常重要的动力混合作用;(4)海水密度在涡旋核心水的分布比较稳定,成层性较强,在混合水区域由于不同的混合作用及其强烈程度不同,会发生波动甚至反转;(5)涡旋本身并不是一个严格对称的结构,涡旋与背景海水的上部以及周围边界比较模糊和复杂,而涡旋下部边界则比较明显.地震海洋学反演提供的涡旋物理性质数据能够为涡旋进一步的研究提供更为准确、更高精度以及更高分辨率的参考数据,同时对涡旋的运动学以及动力学研究提供了更进一步的研究方法和研究方向. 相似文献
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海洋中普遍存在的涡旋对全球海洋热、盐通量有重要贡献.一条于2000年6月在中美洲鹦鹉湾采集的地震剖面L115捕获到了一个海水次表层透镜状反射结构.透镜状反射的宽度约150 km,厚度约500 m,深度从100 m延伸到约600 m,核心深约200 m.结合和地震采集时间近同步的再分析数据中的流速和海水温度数据以及计算的Rossby数和Okubo-Weiss参数,将其解释为气旋涡,且可能是亚中尺度相干涡(SCV).由于地震剖面并未穿过涡旋核心水,涡旋顶底与核心水外层水团的双扩散作用使得剖面上的气旋涡中心表现为上下相邻的强反射双核结构.同航次采集的与L115大致正交的其他几条地震剖面也捕捉到了这个气旋涡.这些剖面整体的反射特征一致性较好,但和L115差异较大,涡旋内部普遍表现为近水平的中等强度反射.涡旋上边界为倾斜的强反射,这是气旋涡的等温线上凸引起的,这里也是亚中尺度锋面的发育区.这些地震剖面的涡旋反射特征的差异表明了该气旋涡空间结构的不对称性和时间演化特征. 相似文献
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地震海洋学是利用反射地震方法探测海水温盐结构的一门新兴交叉学科．其主要优势在于水平方向的分辨率较高，能够弥补传统物理海洋学观测在时空尺度上的缺陷，为研究温盐结构、海洋动力过程提供了一种可视化手段．本文将追溯地震海洋学的发展历程，详细阐述近年在地震剖面和海水温盐结构的关系、内波、地中海涡旋、潜流等海洋学现象研究以及在海水温度结构反演、地震波模拟等定量研究方面的最新进展．最后展望地震海洋学今后的发展，阐述了未来可能取得突破的7个研究领域，如混合，内波的3D波包等． 相似文献
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钠多普勒激光雷达利用中层顶区域的钠原子作为示踪物,探测中层顶区域大气风场和温度剖面.本文主要分析钠多普勒激光雷达的探测原理和大气参数反演算法.利用MSISE和HWM93等大气模型给出背景大气温度、密度及风场,并给定钠原子数密度剖面,从激光雷达方程出发,模拟计算了激光雷达的瑞利散射和钠共振荧光散射回波光子数.利用模拟的回波光子数剖面数据,反演得到大气温度、视线风速和钠原子数密度剖面,反演结果与模拟计算用的背景参数符合很好,验证了这一反演方法的正确性.分析了激光频率偏移和激光线宽变化对反演精度的影响. 相似文献
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一、本文目的海水密度系海水的盐度、温度和压力的连续函数,而在海水的压力每增加1分巴值深度几增加1米的极近似情况下,海水密度即系海水的盐度、温度和深度的连续函数。在必须精确获知海水密度值的要求下,海水的密度是藉它与盐度、温度和压力三者的函数关系计算而得的。为了要使计算所得的海水密度值有一定的精确度,所以海洋盐度、温度和深度调查的精确度就必须有一定的要求。由於中国海皆系浅海,所以本文仅就浅海海洋盐度、温度和深度调查的精确度与海水密度计算的关系加以论述。 相似文献
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反射地震方法一般用于地下地质结构的探测.本文采用南海东北部的一条地震测线记录,通过对水体反射信号的处理,获取了该测线上海水的声速剖面,并获得了海水水体结构的直观图像.在反射地震剖面上,可以看出南海东北部上层海水结构较为稳定,没有明显的水体侵入痕迹,但中、深层海水中内波较为发育,这与物理海洋学上的研究结果是一致的.本文通过设计合理的数据模型说明了地震海洋学这种方法的可行性,并对地震海洋学的工作方法和方向上提出了一些意见和建议. 相似文献
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The influence of sea water velocity variation on seismic traveltimes, ray paths, and amplitude 总被引：2，自引：0，他引：2
The main factors affecting seismic exploration is the propagation velocity of seismic waves in the medium. In the past, during marine seismic data processing, the propagation velocity of sea water was generally taken as a constant 1500 m/s. However, for deep water exploration, the sound velocity varies with the season, time, location, water depth, ocean currents, and etc.. It also results in a layered velocity distribution, so there is a difference of seismic traveltime, ray paths, and amplitude, which affect the migration imaging results if sea water propagation velocity is still taken as constant for the propagation wavefield. In this paper, we will start from an empirical equation of seismic wave velocity in seawater with changes of temperature, salinity, and depth, consider the variation of their values, build a seawater velocity model, and quantitatively analyze the impact of seawater velocity variation on seismic traveltime, ray paths, and amplitude in the seawater velocity model. 相似文献
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We describe a linear Bayesian inversion method to estimate the relevant petrophysical properties of the media forming a reflecting interface from the observations of amplitude variation with incidence angle. Three main steps characterize the proposed approach:
– information from borehole logs are statistically analysed to estimate the empirical models that describe the functional relationship between petrophysical (e.g. porosity, saturation, pressure or depth) and seismic variable(P and S velocities and density);
– the pure-mode (PP) reflection coefficient is parameterized in terms of the relevant petrophysical variables and is linearized in order to implement the linear inversion;
– the sought petrophysical parameters are estimated from the seismic reflected amplitudes by applying the linearized inversion where a priori information, data and model errors and solutions are described by probability density functions.
We test the method on synthetic and real data relative to reflections from a shale/gas-sand interface where the amplitude versus angle response, besides the lithological contrast, is mainly controlled by the saturation and porosity of the sand layer. The outcomes of the linearized inversion are almost identical to those obtained by a previously developed non-linear inversion method demonstrating the applicability of the linear inversion. It turns out that the gas-sand saturation in the range 0%–95% is a poorly resolved parameter while the porosity is the best resolved parameter. The issues of robustness and resolution of the inversion are discussed either through singular value decomposition analysis or the observation of the a posteriori probability density functions.
The linear inversion algorithm, compared with the previously developed non-linear method, reduces significantly the computation time allowing for more extensive applications. 相似文献
– information from borehole logs are statistically analysed to estimate the empirical models that describe the functional relationship between petrophysical (e.g. porosity, saturation, pressure or depth) and seismic variable(P and S velocities and density);
– the pure-mode (PP) reflection coefficient is parameterized in terms of the relevant petrophysical variables and is linearized in order to implement the linear inversion;
– the sought petrophysical parameters are estimated from the seismic reflected amplitudes by applying the linearized inversion where a priori information, data and model errors and solutions are described by probability density functions.
We test the method on synthetic and real data relative to reflections from a shale/gas-sand interface where the amplitude versus angle response, besides the lithological contrast, is mainly controlled by the saturation and porosity of the sand layer. The outcomes of the linearized inversion are almost identical to those obtained by a previously developed non-linear inversion method demonstrating the applicability of the linear inversion. It turns out that the gas-sand saturation in the range 0%–95% is a poorly resolved parameter while the porosity is the best resolved parameter. The issues of robustness and resolution of the inversion are discussed either through singular value decomposition analysis or the observation of the a posteriori probability density functions.
The linear inversion algorithm, compared with the previously developed non-linear method, reduces significantly the computation time allowing for more extensive applications. 相似文献
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南海东北部及邻区，特别是洋陆转换带地区的复杂地壳结构特征一直是南海岩石层结构研究的热点.本文在Pn波地震层析成像结果和深部地震探测剖面的约束下，利用重力数据建立该区两条剖面的密度模型.两条重力剖面二度半密度正反演的拟合结果支持琼粤隆起至吕宋岛弧区一带的地壳结构中存在下地壳高速层的观点，同时认为台西南盆地的拟合结果表明南部凹陷区仍属于过渡型地壳.本文认为剖面AA′和剖面BB′的构造属性虽然均总体倾向于火山岩型，但二者的地质结构并不完全一致，表明了北部陆缘深部结构的横向差异与构造属性的复杂. 相似文献
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G.G. Buffett B. Biescas J.L. Pelegrí F. Machín V. Sallars R. Carbonell D. Klaeschen R. Hobbs 《Continental Shelf Research》2009,29(15):1848-1860
Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts). 相似文献
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常规声波波阻抗由于缺乏横波的信息，使得它对于流体的变化很不敏感，而弹性波阻抗反演，除了与纵波速度，密度有关之外，还与横波速度、入射角度有关，由于考虑了AVO(Amplitude Variation with Offset)效应，使得对流体和岩性的预测能力增强.本文将弹性波阻抗反演应用于时移地震中，采用AVA(Amplitude Variation with Angle)约束稀疏脉冲反演来进行弹性波阻抗反演，得到纵横波阻抗等弹性参数，通过交会图分析，将弹性参数转换为油藏参数，如预测含水饱和度的变化，通过本方法可增强对储层流体的预测，提高储层管理能力. 相似文献