共查询到18条相似文献,搜索用时 187 毫秒
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本文从大地电磁扬的色散关系出发,阐述了进行大地电磁资料一维联合反演的物理意义。论证了对于以色散关系相联系的一对大地电磁响应函数,特别是阻抗实部和虚部视电阻率进行联合反演的必要性和可能的应用前景。对比研究了大地电磁阻抗各单参量及其联合反演的效果。结果表明,在加快反演迭代速度,限定反演解的非唯一性、保证反演迭代的稳定进行等方面,联合反演比单参量反演具有明显的优越性;在大多数情况下,阻抗实部视电阻率和阻抗虚部视电阻率联合反演的效果要比通常所采用的常规视电阻率和阻抗相位的联合反演效果好。实际大地电磁资料的试验表明,各种不同平均阻抗的利用和综合反演解释将有助于获得更为可靠的结果。 相似文献
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为解决地球物理反演中多解性的问题,综合多种地球物理信息的联合反演受到了广泛的关注.本文依据不同地球物理响应可能由相同异常体引起,而不同地球物理分布参数之间存在相关性等特点,提出了一种基于局部Pearson相关系数约束的联合反演方法.该方法假设每个局部区域模型参数的分布具有线性相关特性,在拟合不同类型观测数据时,对局部模型参数施加相关性约束,进行联合反演以减少多解性.本文采用交替迭代联合反演流程,改善了同一目标函数下联合反演收敛性和速度问题.基于新的联合反演方法和流程,我们测试了三维大地电磁和重力仿真数据的联合反演.结果表明,本文提出的基于局部相关性约束的联合反演方法,能充分利用大地电磁和重力观测数据信息,有效改善单一地球物理反演收敛性和多解性的问题,反演效果得到明显提升. 相似文献
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为了准确的探测和描绘地下复杂的地质结构,同时克服地球物理单一方法反演的多解性和单一参数反演模型的不一致性等问题,近年来基于交叉梯度联合反演的综合地球物理解释已经得到了广泛的关注和应用.本文首先研究了两种地球物理方法的交叉梯度联合反演算法,在此基础上,推导并实现了多种地球物理方法(大地电磁,重力,磁法,地震初至波走时)的多交叉梯度约束的二维联合反演算法;其次,我们设计了结构不一致模型和复杂模型,针对多物性联合反演算法的准确性和有效性进行了模拟试算,并对复杂模型的单独反演结果和联合反演结果进行了交叉梯度值和物性交会图的对比;最后,本文将成熟的卫星资料多光谱综合分析技术应用到联合反演中,将多物性参数反演模型结果图通过RGB(红-绿-蓝)模式进行合成,得到融合的RGB合成图.结果表明:通过对结构不一致模型和复杂模型的联合反演结果和单独反演结果的对比分析,可以得出联合反演得到的结果更接近真实模型,并从得到的交叉梯度值进一步证明了联合反演模型相似度高,也从物性交会图中得到联合反演的物性相关性更好的结论,反向证明了算法的正确性.最终从得到的RGB合成图像,我们可以更直观的分析反演结果,更有利于准确划分地下模型结构. 相似文献
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对不同地球物理方法的数据进行联合反演,通过模型参数的相互约束可以减小反演的多解性.本文对电阻率法和重力勘探数据开展了基于电阻率和剩余密度梯度累加约束的二维联合反演研究.电阻率法采用数据空间Occam反演,重力勘探采用基于对数障碍法的正则化反演.通过在电阻率法和重力勘探反演的目标函数中引入电阻率和剩余密度梯度累加约束项,利用交替迭代方式实现了电阻率法和重力勘探数据的二维联合反演.对理论模型合成数据进行了单方法反演和联合反演,对比了反演效果.结果表明:联合反演结果优于单方法反演结果,联合反演结果对异常体的物性值恢复和形态刻画效果更好. 相似文献
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JAN HELGESEN 《Geophysical Prospecting》1991,39(3):313-336
Three methods for least-squares inversion of receiver array-filtered seismic data are investigated: (1) point receiver inversion where array effects are neglected; (2) preprocessing of the data with an inverse array filter, followed by point receiver inversion; (3) array inversion, where the array effects are included in the forward modelling. The methods are tested on synthetic data generated using the acoustic wave equation and a horizontally stratified earth model. It is assumed that the group length and the group interval are identical. For arrays that are shorter than the minimum wavelength of the emitted wavefield, and when the data are appropriately muted, point receiver inversion (first method) gives satisfactory results. For longer arrays, array inversion (third method) should be used. The failure of the inverse array filter (second method) is due to aliasing problems in the data. 相似文献
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探讨了使用台站接收函数反演得到上地幔速度结构和间断面深度的一种方法——剥壳遗传算法. 由地表至深部分成几个深度段,逐段反演速度结构,并在接收函数曲线上剥离浅处间断面的多次反射震相和反射转换震相对深部间断面的一次透射转换相的影响. 在每一深度段使用浮点编码、算术杂交和非均匀变异的遗传反演方法;在10次独立反演后,依据适应度选出50个优秀模型,对其加权平均得到该段的最终速度结构. 所形成的方法和程序,用iasp’91模型进行数值检验之后,又反演了海拉尔台的观测接收函数,给出台下深至700km的速度结构和主要间断面埋藏深度及速度跃变量. 相似文献
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本文对大地电磁阻抗相位资料的性质及其意义作了总结和评述。文中述及的阻抗相位资料正则化反演方法,是在文献〔1〕的基础上进行了改进,笔者就此给出了实际算例和概要分析 相似文献
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LUIGI ZANZI 《Geophysical Prospecting》1990,38(4):339-364
The aim of refracted arrivals inversion is the computation of near-surface information, i.e. first-layer thicknesses and refractor velocities, in order to estimate the initial static corrections for the seismic data. The present trend is moving towards totally automatic inversion techniques, which start by picking the first breaks and end by aligning the seismic traces at the datum plane. Accuracy and computational time savings are necessary requirements. These are not straightforward, because accuracy means noise immunity, which implies the processing of large amounts of data to take advantage of redundancy; moreover, owing to the non-linearity of the problem, accuracy also means high-order modelling and, as a consequence, complex algorithms for making the inversion. The available methods are considered here with respect to the expected accuracy, i.e. to the model they assume. It is shown that the inversion of the refracted arrivals with a linear model leads to an ill-conditioned problem with the result that complete separation between the weathering thickness and the refractor velocity is not possible. This ambiguity is carefully analysed both in the spatial domain and in the wavenumber domain. An error analysis is then conducted with respect to the models and to the survey configurations that are used. Tests on synthetic data sets validate the theories and also give an idea of the magnitude of the error. This is largely dependent on the structure; here quantitative analysis is extended up to second derivative effects, whereas up to now seismic literature has only dealt with first derivatives. The topographical conditions which render the traditional techniques incorrect are investigated and predicted by the error equations. Improved solutions, based on more accurate models, are then considered: the advantages of the Generalized Reciprocal Method are demonstrated by applying the results of the error analysis to it, and the accuracy of the non-linear methods is discussed with respect to the interpolation technique which they adopt. Finally, a two-step procedure, consisting of a linear model inversion followed by a local non-linear correction, is suggested as a good compromise between accuracy and computational speed. 相似文献
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利用线性化的技巧及G.Beylkin引进的奇性反演的概念,使波动方程非均匀背景场的反演问题有了实质性的进展,但在进行线性化简时,往往会将数值小但奇性高的项略去,因而使反演结果失真,本文利用小波变换这一工具,在化简时保留了奇性的主要部分,从而使反演所得的结果从奇性分析的观点看来更为。 相似文献
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本文将反演理论用于由体波观测走时反演匀速水平层的地壳模型参数,探讨了基本原理,提出了两种反演地壳结构的方法,同时还对假设的模型进行了验算,表明所用方法是有效的。 相似文献