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- Volume 28, Issue 2, 1980
Geophysical Prospecting - Volume 28, Issue 2, 1980
Volume 28, Issue 2, 1980
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RESIDUAL STATIC CORRECTIONS—ITERATIVE SOLUTION ANALYSIS*
More LessAbstractThe iterative estimation process of residual static corrections published earlier is further analyzed.
The convergence and convergence rate of the iterative solution are analysed for components of different relative wave length with results of both theoretical and practical value.
Relative wave length components practically determinable and indeterminable are defined.
One model example is presented for illustrative purposes.
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IMPROVEMENTS IN THE OBSERVATION OF SHEAR WAVES*
More LessAbstractThe observation of shear waves is finding more interest in seismic exploration, especially for the determination of additional lithologic parameters, e.g. Vp/Vs. We demonstrate the observation of converted waves in routine seismic work by means of horizontal geophones. Field technique and data processing permit acquisition and interpretation of converted waves in connection with routine seismic measurements. A special interpretation of the recorded converted waves results in the shear wave velocity and the Vp/Vs relation.
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COMPUTATION OF THE NORMAL MOVEOUT VELOCITY IN 3D LATERALLY INHOMOGENEOUS MEDIA WITH CURVED INTERFACES*
By P. HUBRALAbstractFor a 3D velocity model of curved first order interfaces and layer velocities which are arbitrary smooth functions of the space coordinates, the normal moveout (NMO)‐velocity can be computed by numerically integrating a system of first order ordinary differential equations for a hypothetical wavefront that originates at the normal incidence point of the normal ray and moves up along the ray to the common mid‐point of the common datum point (CDP) profile.
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GENERALIZED KUNETZ‐TYPE EQUATIONS*
By J. M. MENDELAbstractA Kunetz equation is often used as the starting point in the development of solutions for the inversion of one‐dimensional, noise free, normal incident seismograms, for which |ro|= 1. In this paper we demonstrate a need for a Kunetz‐type equation in which filtered signals can be used, so that noise effects can be reduced. We then show that an infinite number of Kunetz‐type equations exist for the lossless wave equation in layered media. Finally, we show that it is indeed valid to formulate and solve the inverse problem using filtered signals.
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DIRECT RESISTIVITY INTERPRETATION BY ACCUMULATION OF LAYERS*
By E. SZARANIECAbstractThe asymptotic approximation of Pekeris is replaced by two new procedures referred to as the two‐point method and the multilayer method, other steps in the direct interpretation remaining unmodified. The new methods are based on the assumption that there are at least one or two consecutive sample points of the kernel curve containing the information on a particular layer and containing no information on the deeper layers. In any step, the identified covering layers are accumulated and the interpretation progresses to the successive deeper layer.
The multilayer method is oriented towards interpretation of data severly contaminated by noise. The elimination of noise with simultaneous averaging of layer parameters is performed in the domain of Dar Zarrouk parameters.
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INFLUENCE OF A CONDUCTING SHIELD IN THE ONE‐LOOP VERSION OF THE TRANSIENT PULSE INDUCTION METHOD*
Authors R. NAGENDRA, I.B. RAMAPRASADA RAO and V.L.S. BHIMASANKARAMAbstractThe transient response of a conductive shell‐shell model in the one‐loop version was obtained analytically. The results indicate that four zones, namely early, late early, intermediate, and late zone can be identified in the total transient characteristic of the model. In case the measurements are carried out in the late early zone, a conductive target appears as a resistive one. It is suggested that the optimum time of measurement should be so selected as to fall in the intermediate zone.
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DIPOLE‐DIPOLE DEEP GEOELECTRIC SOUNDINGS OVER GEOLOGICAL STRUCTURES*
By L. ALFANOAbstractAlfano L. 1980, Dipole‐Dipole Deep Geodectric Soundings over Geological Structures, Geophysical Prospecting 28, 283–296.
The dipole‐dipole array is used for deep vertical geoelectric soundings for practical reasons. However, the data obtained are often too scattered and the quality is lower than that of a Schlumberger sounding. The mathematical transform from these fields data to the corresponding Schlumberger ones is needed. It is demonstrated that for more general underground structures different from plane parallel stratifications, only the continuous polar dipole‐dipole array permits a general and reliable transform of this type. It follows that any other dipole‐dipole array, (for instance the azimuthal, equatorial, parallel, perpendicular, etc.), are useless over complex structures, or in the presence of irregularities on the ground surface.
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THEORY FOR THE BIPOLE‐DIPOLE METHOD OF RESISTIVITY SOUNDING*
Authors U.C. DAS and SAURABH K. VERMAAbstractA theory for the bipole‐dipole method of resistivity sounding is developed. Bipole‐dipole apparent resistivities are related to Schlumberger apparent resistivities at two spacings. The theory can also be used to compute exact dipole‐dipole apparent resistivity curves providing an improvement over the existing techniques which involve far field approximations. A comparison of bipole‐dipole and dipole‐dipole systems reveals the similarity between the two. However, the resolution of the bipole‐dipole system depends on the azimuth angle. The flexibility of the theoretical expressions lead to a generalized field scheme independent of the bipolar or dipolar nature of the current source.
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Volumes & issues
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Volume 72 (2023 - 2024)
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Volume 71 (2022 - 2023)
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Volume 70 (2021 - 2022)
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Volume 69 (2021)
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Volume 68 (2020)
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Volume 67 (2019)
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Volume 66 (2018)
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Volume 65 (2017)
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Volume 64 (2015 - 2016)
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Volume 63 (2015)
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Volume 62 (2014)
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Volume 61 (2013)
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Volume 60 (2012)
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Volume 59 (2011)
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Volume 58 (2010)
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Volume 57 (2009)
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Volume 56 (2008)
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Volume 55 (2007)
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Volume 54 (2006)
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Volume 53 (2005)
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Volume 52 (2004)
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Volume 51 (2003)
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Volume 50 (2002)
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Volume 49 (2001)
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Volume 48 (2000)
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Volume 47 (1999)
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Volume 46 (1998)
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Volume 45 (1997)
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Volume 44 (1996)
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Volume 43 (1995)
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Volume 42 (1994)
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Volume 41 (1993)
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Volume 40 (1992)
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Volume 39 (1991)
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Volume 38 (1990)
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Volume 37 (1989)
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Volume 36 (1988)
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Volume 35 (1987)
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Volume 34 (1986)
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Volume 33 (1985)
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Volume 32 (1984)
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Volume 31 (1983)
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Volume 30 (1982)
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Volume 29 (1981)
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Volume 28 (1980)
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Volume 27 (1979)
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Volume 26 (1978)
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Volume 25 (1977)
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Volume 24 (1976)
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Volume 23 (1975)
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Volume 22 (1974)
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Volume 21 (1973)
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Volume 20 (1972)
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Volume 19 (1971)
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Volume 18 (1970)
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Volume 17 (1969)
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Volume 16 (1968)
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Volume 15 (1967)
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Volume 14 (1966)
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Volume 13 (1965)
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Volume 12 (1964)
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Volume 11 (1963)
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Volume 10 (1962)
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Volume 9 (1961)
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Volume 8 (1960)
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Volume 7 (1959)
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Volume 6 (1958)
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Volume 5 (1957)
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Volume 4 (1956)
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Volume 3 (1955)
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Volume 2 (1954)
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Volume 1 (1953)