摘要:

AbstractThe automatic picking of seismic sections replaces the slow and painstaking task of manual reflection plotting with rapid and economical processing by computer. Essentially, reflection picking is a decision‐making problem which also can be considered as a sort of filtering. Mathematically this means multiplying the seismic data matrix by a more or less complex decision operator.For the sake of economy, we give an initial solution for simple cases which only require easily automatized decision‐making criteria.We describe another more elaborate method for use in examining seismic phenomena which are more difficult to spot.The process used is based on the recognition of shapes and consists first of all of determining a series of characteristics capable of identifying each reflection on each trace and then of comparing these different characteristics from trace to trace so as to be able to judge the continuity or discontinuity of the reflections.Automatic picking thus leads to a schematic time‐section in which only the horizons found by calculation are retained. An automatic migration program then transforms this time‐section into a depth

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02125.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe relationship between porosity and formation factor in unconsolidated homogeneous and anisotropic sediments without granule‐liquid interaction is investigated by introducing a parametric model that simulates a variable cellular structure.In this hypothesis, porosity φ andF‐factor are calculated for some fixed values of the parameter, solving numerically two integral expressions.From these calculations the form of the function φ=f(F), corresponding to the proposed model, has been deduced. This relation is in very good agreement with Archie's empirical law for unconsolidated sands which requires thatF=φ‐‐1,3. Therefore it seems that the validity of Archie's law is theoretically confirmed for the unconsolidated sediments considered in

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02126.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn the theoretical part of the present paper, formulas have been analyzed for a magnetic dipole in a homogeneous and unbounded medium. The magnetic field is elliptically polarized in the region between the quasistatic zone and the far field. Since the position and the shape of the polarization ellipses depend on the complex wave number,k, it is possible to determinekby measuring the polarization ellipses. Fromk, the conductivity and the dielectric constant of the medium are easily calculated. The functions required for the measuring method have been computed and plotted in graphs.In the experimental part it was examined how far the theory may be applied to measurements of propagation through rock at frequencies ranging from 100‐1000 kHz. These measurements showed that reasonably defined mean values of rock parameters can be given only if the deviations of the field from the theoretically expected field are not too high. These deviations have been named field distortions and have been examined by means of statistical methods (variance ratio tests). Gallery cavity and inhomogeneity or anisotropy of the medium account for these distortion

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02127.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractA number of electrical resistivity arrays are available to the exploration geophysicist in the conduct of vertical or horizontal profiling. The advantage of using central‐type arrays which produce large potential drops, such as the Wenner or the Schlumberger, must be weighed against the ease of acentral arrays such as the polar and equatorial arrays.A series of nomograms has been designed to provide a means of rapid calculation of the potential drop to be obtained by any of the various central and acentral arrays, as a function of apparent resistivity, electrode spacings and available transmitter power. The same nomograms may also be used for approximate computation of the apparent resistivities in routine surveys. However, the accuracy of resistivity calculation is directly related to the accuracy of drawing lines between the scales and hence is rather limited in reduced‐size nomograms in this pa

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02128.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn a previous publication (Koefoed 1968) a function called the “raised kernel function” has been introduced as an intermediate function in the interpretation of resistivity sounding data, and methods have been described both for the determination of the raised kernel function from the apparent resistivity function, and for the determination of the layer distribution from the raised kernel function.In the present paper a procedure is described by which the second step in this interpretation method–i.e. the determination of the layer distribution from the raised kernel function–is considerably accelerated. This gain in interpretation speed is attained by the use of a standard graph for a function which defines the reduction of the raised kernel function to a lower boundar

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02129.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

RésuméLes méthodes sismiques à signaux longs du type Vibroseisréclament un traitement qui consiste en la crosscorrélation des signaux reçus avec le signal émis. Cette opération qui est effectuée par des ordinateurs puissants, équipés de convolueurs, est aussi réalisée de manière analogique. Lorsque le volume des données à traiter devient trés important comme c'est le cas en sismique marine, il peut être intéressant ?avoir recours au principe décrit dans cet article, qui utilise une source de lumière cohérente. Une étude de la dyna‐mique et des exemples

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02130.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractNon dynamite seismic energy sources have shown only limited success in difficult shallow‐water or marsh prospect areas, and none have applicability to both environments. Recently, a method has been devised to adapt a marine pneumatic source for operation in abrasive surroundings. A system composed of four of these modified sources together with associated emplacement and retrieval mechanisms has been developed and has proven to be a reliable and efficient seismic energy source for both shallow‐water and marsh applicati

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02131.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

RésuméOn présente des profils de sismique réflexion obtenus dans la partie Sud‐Est du Golfe de Gascogne en eau profonde avec raccordement au plateau continental.La technique employée était celle du Flexotir à un ou deux canons en couverture triple. La charge totale par tir était égale à 50 ou 100 grammes suivant les cas. La vitesse du navire était ?environ 6,5 nœuds, ce qui a permis de couvrir 1000 kilomètres de profil en 9 jours de travail. La distance entre traces sur les coupes est de 60 mètres, ce qui per‐met une étude assez détaillée.De bons résultats ont été obtenus par des fonds allant jusqu à 4000 mètres. La pénétration sous le fond atteint souvent 5 secondes (temps double).Le Flexotir constitue une méthode de prospection sismique bien adaptèe àľocéano

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02132.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractA second deep Schlumberger sounding has been carried out in South Africa, this time using a newly completed power transmission line, not yet in sevice, as emission line. The maximum current electrode separation attained was 600 km. The sounding was situated on a shield area with a thin cover of sedimentary rocks (Karroo System) overlying the archaean granite. The center was chosen near to the village of Dealesville.It is shown that lateral effects at largeABspacings are unlikely, but due to numerous dolerite intrusions in the sediments surface electrode effects must be guarded against; thusABpositions were chosen by geologists. Because of a low signal/noise ratio at largeABspacings the measurements were treated statistically; in particular, the elimination of non‐random events improved the measuring accuracy.Although a thin conducting layer at the base of the sedimentary succession decreased the resolution of the sounding curve, the results, which were interpreted with the aid of a computer, show positively that(a). the crust is multi‐layered with a highly resistant portion having a minimum resistivity of 15000 ohm.m and(b). a good, thick conductor appears as the final layer.The Dealesville results are in complete agreement with those obtained from the first deep Schlumberger sounding at Pofadder (Van Zijl 1969) except that the transverse resistance of the lowermost resistant crust is about 100% larger at Pofadder due probably to a second period of metamorphism. Both electrical studies support the view of a dehydrated lower crust (granulite

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02133.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY