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  • 1
    Electronic Resource
    Electronic Resource
    Reflector imaging (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 110 (1992), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A method is presented to image a reflecting discontinuity of the earth parameters. As model data we take the boundary integral representation in which we employ a locally plane reflector approximation. We separate the horizontal phase from the vertical phase in the data by employing a Radon transform with respect to the horizontal source and receiver coordinates. Carrying out a high-frequency analysis and taking the vertical slowness as an independent variable, the resulting Fourier integral is inverted to the space-time domain. We arrive at a function with a laterally variant vertical traveltime that represents a space-time image of the profile of the interface as the envelope of the first arrivals. The method shows clearly how the data in the source-receiver domain have to be collected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1992.tb00721.x
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    SEISMIC INVERSION BY A RMS BORN APPROXIMATION IN THE SPACE-TIME DOMAIN (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 37 (1989), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A new approximate method to calculate the space-time acoustic wave motion generated by an impulsive point source in a horizontally layered configuration is presented. The configuration consists of a stack of fluid layers between two acoustic half-spaces where the source and the receiver are located in the upper half-space. A distorted-wave Born approximation is introduced; the important feature of the method is the assumption of a background medium with vertical varying root-mean-square acoustic wave speed. A closed-form expression for the scattered field in space and time as a function of the contrast parameters is deduced. The result agrees closely with rigorously calculated synthetic seismograms. In the inverse scheme the wave speed and mass density can be reconstructed within a single trace. Results of the inversion scheme applied to synthetic data are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1989.tb01821.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Non-linear three-dimensional inversion of cross-well electrical measurements [Paper pres] (2000)
    Oxford BSL : Blackwell Science Ltd
    Geophysical prospecting 48 (2000), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Cross-well electrical measurement as known in the oil industry is a method for determining the electrical conductivity distribution between boreholes from the electrostatic field measurements in the boreholes. We discuss the reconstruction of the conductivity distribution of a three-dimensional domain. The measured secondary electric potential field is represented in terms of an integral equation for the vector electric field. This integral equation is taken as the starting point to develop a non-linear inversion method, the so-called contrast source inversion (CSI) method. The CSI method considers the inverse scattering problem as an inverse source problem in which the unknown contrast source (the product of the total electric field and the conductivity contrast) in the object domain is reconstructed by minimizing the object and data error using a conjugate-gradient step, after which the conductivity contrast is updated by minimizing only the error in the object. This method has been tested on a number of numerical examples using the synthetic ‘measured’ data with and without noise. Numerical tests indicate that the inversion method yields a reasonably good reconstruction result, and is fairly insensitive to added random noise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2478.2000.00170.x
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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