共查询到19条相似文献，搜索用时 390 毫秒
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磁异常的反演是地球物理勘探的重要手段,三维磁化率反演是磁异常定量解释中的一种重要方法.由于剩磁的存在使得磁化方向与地磁场方向产生偏差,从而影响了磁异常反演与解释的精度.本文基于磁异常模量反演和磁化强度矢量反演方法得到了一种新的磁化强度矢量反演方法.与以往的磁化强度矢量反演方法相比,该方法以磁异常模量反演得到的磁化率模型为约束,采用Lp范数正则化方法求解,提高了磁化强度矢量反演的精度和效率.本文通过模拟试验的反演计算,验证了这种磁化强度矢量反演方法的有效性.最后,将本文方法应用于新疆东天山卡拉塔格地区航磁数据的解释,获得了地下空间不同磁性差异的磁性体的空间分布特征,为进一步分析研究区隐伏矿床提供了重要信息. 相似文献
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强剩磁、强退磁改变了总磁化强度的大小和方向,给磁测资料解释带来困难.为此,本文利用二维井中磁测数据反演磁化强度矢量的二维分布.首先利用井中磁测的磁异常模量反演磁化强度大小的分布.然后,在已知磁化强度大小分布的前提下,拟合磁场分量,反演磁化强度方向的分布.其中,磁化强度大小和方向均用共轭梯度法求解,并通过预优矩阵改善磁化强度大小的反演效果.理论模拟说明,该方法能准确获得磁化强度矢量分布.磁化强度矢量反演结果包括感磁、剩磁及退磁的影响,这为研究强剩磁、高磁化率矿床提供了一种有效方法. 相似文献
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磁梯度张量系统姿态的变化将影响梯度场测量和数据解释的精度,使得具有坐标变换不变性特点的张量不变量成为磁梯度张量数据解释的研究热点.本文在对磁偶极子产生的磁梯度张量进行特征值分析的基础上得到了:测量点与磁偶极子位置形成的位置矢量、磁偶极子磁矩矢量与绝对值最小的特征值对应的特征向量垂直;位置矢量和磁矩矢量与最大及最小特征值对应的特征向量共面,且两矢量间的夹角可由磁梯度张量矩阵的特征值表示.最后,将本文所得磁偶极子梯度张量的几何不变量用于磁性目标的跟踪中,取得了较好的实时跟踪效果. 相似文献
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在地质体具有较强剩磁或自退磁效应的情况下,获得地质体总磁化方向对磁法勘探的数据处理、反演及解释具有重要意义.与传统航磁总场测量相比,航磁矢量(三分量)测量能够获得地磁场的矢量信息.基于三分量磁异常一阶矩与磁源磁矩的积分关系,我们实现了基于航磁矢量数据的磁源总磁化方向估算.针对该方法易受相邻异常影响,从而使多异常的估算难以确定磁源中心位置的问题,分析了在不同磁化倾角下,估算的磁化偏角、倾角与实际磁源中心位置的关系,并根据该关系采取了限定估算区域的方法,获得了多异常的估算结果.将该方法应用于东天山启鑫地区实测航磁三分量数据,估算了具有强剩磁的启鑫岩体总磁化方向,并将估算的方向应用于化极计算.化极结果显示,减少了启鑫岩体磁异常受斜磁化的影响,且与磁异常模量计算结果类似.该方法假设磁源均匀磁化,估算结果可视为地质体总磁化方向的整体体现,对强剩磁地质体磁异常的数据处理、反演及解释具有实际意义. 相似文献
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本文利用广州地磁台1961年4月至1963年3月记录到的连续磁扰变化,经过模数转换、谱分析和数字滤波,得到了大量不同短周期的磁变事件,再将周期相同的事件取三个月滑动组合求得转换函数。结果表明:广州台不同短周期的磁扰矢量△B在球极坐标上的投影均趋于同一水平面;转换函数A、B及帕金森矢量(Parkinson)长度CP随时间的异常变化与广东省河源县1962年3月19日Ms6.1级地震有关。本文还讨论了该台转换函数A、帕金森矢量长度CP及倾角I与地磁周期的关系,得到周期为9至40分钟时的A、CP、I之年均值与磁变周期呈线性相关。故认为研究广州台地磁周期小于40分钟的转换函数随时间的变化,可获得以电导率异常为标志的地震前兆信息。 相似文献
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磁尾电流片在磁尾动力学过程中起着重要作用.卫星观测表明磁尾电流片经常处于拍动状态.但磁尾电流片拍动的特性和产生机制至今仍然没有被完全弄清楚.本文主要利用欧洲空间局Cluster卫星数据,研究一个伴随高速离子流的电流片拍动事件.该电流片拍动事件具有很强的周期性.拍动的周期约是2min,磁场振荡幅度约为20nT.能量电子和离子的通量具有周期性增强和减弱的特征.电流密度X和Y分量也具有周期性的振荡,并且振荡周期与磁场振荡周期一致.通过对粒子流速矢量与电流矢量的分析,发现粒子运动具有涡旋的特征.因此可以推断,该磁尾电流片的拍动不是由磁尾等离子体片高速流产生的,而是与局地等离子体不稳定性有关. 相似文献
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菏泽地磁台距菏泽5.9级地震仅15km,是总结地磁转换函数异常变化的震例的极好机会,所以这项研究工作非常有意义.读完文献[1]后,我有一个很大的疑问:在一般情况下,菏泽地磁台的感应矢量是否会那么大?从图5及图6可以看出,虽然A_i,B_i不大,但A_r及B_r却很大.由A_r及B_r组成的实感应矢量(real induction arrow)的模大致上 相似文献
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菏泽地磁台距菏泽5.9级地震仅15km,是总结地磁转换函数异常变化的震例的极好机会,所以这项研究工作非常有意义.读完文献[1]后,我有一个很大的疑问:在一般情况下,菏泽地磁台的感应矢量是否会那么大? 相似文献
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计算分析了银川台１９８３年１月～１９９６年１０月的地磁周期Ｔ＝９～２００ｍｉｎ的复转换函数Ａ的模｜Ａ｜、总误差σｚ和帕金森矢量或韦氏矢量,并将其在银川台４００ｋｍ范围内８次中强地震发生时的变化进行了研究。结果表明：周期为１２、２０、２６、３５、４５、６０、７５、９０ｍｉｎ的｜Ａ｜、σｚ磁方位角αｐ及其方差Δαｐ在震前有明显的异常变化,帕金森矢量或韦氏矢量在震前指向震中。 相似文献
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导了磁化强度矢量层析成像方程,并与磁化强度标量层析成像方程进行了对比. 使该矢量层析成像方程既适用于三维的也适用于二维,既适用于使用磁场垂直分量资料,也适用于使用磁场总强度资料. 本文采用改进的高斯-赛德尔迭代求解磁化强度矢量层析成像方程,在求解方程中引进了与深度有关的权系数. 并对二维模型开展了正反演研究. 当模型层数为二层,且每层51个柱体时,采用零初始模型就能获得较好的磁化强度垂直分量和水平分量反演结果,除了异常体边部外,磁化方向比较可靠. 当模型层数为五层,且每层51个柱体时,采用零初始模型不能得到较好结果,改用接近背景值的均匀初始模型,反演的磁化强度垂直分量和水平分量大致接近真实,但不能刻划某些细节. 相似文献
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TAPIO RUOTOISTENMÄKI 《Geophysical Prospecting》1993,41(4):413-433
Magnetic anomalies of complicated 3D sources can be calculated by using a combination of analytical and numerical integration. Two surfaces and the magnetization parameters (the amplitudes of the induced and remanent components and the direction cosines) of the source can be defined by arbitrary functions or by discrete data points in a plane. When combined with a polynomial magnetization function in the direction of the third axis, 3D magnetization distribution can also be modelled. The method gives very general equations for anomaly calculation. It can be used for direct modelling of sources interpreted by seismic or other methods and also for interactive interpretation with fast computers. It is possible to calculate anomalies of, for example, intrusives or folded sedimentary beds whose surfaces are functions of horizontal coordinates and which have polynomial magnetization variations in the vertical direction due to gravitational differentiation and arbitrarily varying magnetization in the horizontal direction due to regional metamorphosis. If the distribution of magnetization parameters in the vertical direction cannot be described satisfactorily by polynomials, models can be used whose surfaces are functions of the vertical coordinate and which can then have any arbitrary magnetization distribution in the vertical direction. 相似文献
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We present a new method to estimate the direction of the magnetization vector of geological bodies based upon the correlation between the reduced-to-the-pole field for tentative values of the magnetization direction and the total magnitude anomaly, obtained by a transform of the measured magnetic field. The reduced-to-the-pole and the total magnitude anomaly are centred over the sources in the case of 2D anomalies or well-centred in the case of compact 3D sources and have similar patterns for the same source. The method has several important advantages over similar transform-correlation methods for estimation of the magnetization direction. It calculates only one transform for many tentative values of the magnetization direction. The method does not use derivatives of any order and relies on confident isolation of the target anomalies based on one of the compared transforms, the total magnitude anomaly. We studied the performance of the method on five 2.5D and compact 3D sources. We analysed possible inherent to the method errors, as well as errors due to interference from neighbouring sources. Finally, we estimated the magnetization-vector direction of the main sources causing the magnetic field in the Burgas region and the adjoining southeast Bulgarian Black Sea shelf. The sources in the Black Sea shelf show prevalently reverse magnetization, while the sources on land have normal or reverse magnetization. 相似文献
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This paper describes application of a fast inversion method to recover a 3D susceptibility model from magnetic anomalies. For this purpose, the survey area is divided into a large number of rectangular prisms in a mesh with unknown susceptibilities. Solving the full set of equations is substantially time consuming, and applying an algorithm to solve it approximately can reduce the time significantly. It is shown that the Lanczos bidiagonalization method can be an appropriate algorithm to solve a Tikhonov cost function for this purpose. Running time of the inverse modeling significantly decreases by replacing the forward operator matrix with a matrix of lower dimension. A weighted generalized cross validation method is implemented to choose an optimum value of a regularization parameter. To avoid the natural tendency of magnetic structures to concentrate at shallow depth, a depth weighting is applied. This study assumes that there is no remanent magnetization. The method is applied on a noise-corrupted synthetic data to demonstrate its suitability for 3D inversion. A case study including ground based measurement of magnetic anomalies over a porphyry-Cu deposit located in Kerman providence of Iran, Now Chun deposit, is provided to show the performance of the new algorithm on real data. 3D distribution of Cu concentration is used to evaluate the obtained results. The intermediate susceptibility values in the constructed model coincide with the known location of copper mineralization. 相似文献
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井间电磁测量的2．5维层析成像方法 总被引：1，自引：0，他引：1
利用正则化最小二乘反演方法实现了井间电磁测量数据的层析成像,对井间地层电阻率进行了重建。在成像算法中,我们假设了井间电磁的激发与接收采用电磁偶极子源,井间介质仅在二维（xoz）平面内变化。在数值模拟中,通过对构造走向（y方向）的Fourier变换,将三维电磁场问题转化为一系列二维问题,用等参有限元方法在波数域求解,使实际地层模型的处理得以实现。对于波数域中每个波数对应的电磁场方程采用等参有限元求解,并用高斯积分将波数域解变换为空间域电磁场。利用源与接收器电磁场的互易原理,实现了电磁场响应对电导率分布灵敏度的快速计算。针对正演模拟中源点的奇异性,我们采用具有一定面积的伪艿函数表达源电流分布,使数值解精度得到提高。用层状介质的解析解与数值计算结果的对比,验证了模拟算法的精度。用介质扰动产生的电磁场变化检验互易性定理计算灵敏度的有效性。对简单块状模型、斜向裂缝带模型及“大”字模型的模拟数据成像结果表明,本文介绍的层析成像方法是正确有效的。 相似文献
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Zsuzsanna Nyári Ali Ismet Kanlı János Stickel Axel Tillmann 《Journal of Applied Geophysics》2010,70(3):255-265
The spatial distribution of the electrical resistivity data provides useful information for investigating and modeling the fluid transport processes. 3D electrical resistivity distribution provides information about water flow and changes in electrical resistivity of the pore fluid.Therefore, to assist in understanding and modeling of the fluid transport process, 3D spatial distribution of the electrical resistivity data with the corresponded 3D geological section were mapped and interpreted in the test site located in western Germany. A process of deriving electrical resistivity values from the mechanical and radioactive parameters of cone penetration tests (CPT) and geological information of boreholes was presented. A reliable method which gives accurate resistivity values in cases of near surface sediments was introduced. Then a field test was executed where the calculated resistivity values were compared with the measured CPTe resistivity data. The CPTe (cone penetration test with electrical extension) data were also used in correlating to the ERT (electrical resistivity tomography) data. Consequently, obtained dense CPT surveys give us the possibility to determine a high resolution resistivity distribution of the investigated area. 相似文献
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高精度、快速有效的正演模拟算法是三维电磁正反演的前提.为了提高海洋电磁三维数值模拟的精度和效率,本文提出利用基于Gauss-Lobatto-Chebyshev（GLC）基函数的谱元法进行海洋可控源三维电磁正演模拟.谱元法结合有限元法和谱方法的优点.我们通过应用伽辽金加权残差法离散二次电场矢量亥姆赫兹方程,在单元内选择混合阶GLC多项式的张量积作为高阶矢量插值基函数,在求解大型稀疏线性方程组时利用直接求解器进行快速求解,从而实现了三维海洋可控源电磁快速高精度正演模拟.一维和三维模型正演结果验证了本文算法的有效性和准确性.典型模型的数值结果表明谱元法是一种有效的三维海洋可控源电磁正演数值方法,能在稀疏网格剖分情况下获得精确的海洋电磁正演模拟响应. 相似文献
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A. B. Raevskii 《Izvestiya Physics of the Solid Earth》2008,44(7):548-554
An iterative algorithm is proposed for magnetic induction modulus inversion. The iterative process is based on a recurrence relation for the squared induction modulus, which can be represented at each iteration step by a system of linear algebraic equations for components of the magnetization vector. Formulas for the calculation of matrix elements of this system and the determination of the magnetization at the next iteration step are given. Model and practical examples illustrating the reconstruction of magnetization and anomalous field components are presented. 相似文献