bluuebunny/crossref_metadata_2025_split huggingface dataset:
THEORETICAL RESISTIVITY ANOMALIES ACROSS A SINGLE VERTICAL DISCONTINUITY
Authors: AL‐CHALABI MAHBOUB 
Published: April 2006

AbstractElectrical resistivity anomalies of a symmetrical four‐electrode co‐linear system across a single vertical discontinuity are treated in relation to: a) the ratio of potential electrode separation to the current electrode separation that are employed in the system and b) the angle which the electrode alignment makes with the discontinuity. Several conclusions are extracted from this treatment and methods for obtaining an optimum sensitivity of the system, with respect to these parameters, are shown. Disadvantages of special arrangements, such as the Wenner configuration, are indicated. Methods are outlined to utilise variations in the apparent resistivity plot for determining the angle between the electrode alignment and the discontinuity, quantitatively or qualitatively. These variations include certain deviations from the standard curves obtained in longitudinal traverses made at right angles to the discontinuity. Also, a comparison is made between longitudinal and cross traverses, in relation to the discontinuity.
CONTRIBUTION DU TRAITEMENT NUMERIQUE A L'ANALYSE ET A INTERPRETATION DES ENREGISTREMENTS REFRACTION*
Authors: PERALDI R. 
Published: April 2006

AbstractThe tools used in digital processsing have received little application, to date, to refraction seismic.It seems however that some problems encountered in the analysis of refraction records could be solved through techniques which are of common use in processing of reflection seismic data (correlation, stacking, f and k filtering).The experiments made with some of these techniques revealed the possibility of a more complete refraction record analysis, allowing the study of later arrivals.The interpretation of these records could also, to a fairly large extent, be automated by means of digital processing.While recording, some care ought to be taken to allow identification and interpretation by digital processing of as many events as possible. However, the results shown here have been obtained from fairly old analog records, for which no particular care had been taken, which makes it possible to complete and revise the interpretation of previous studies using the same processing techniques.Long line refraction shooting is justified for marine surveys in some areas, particularly where reflection is disturbed by singing; improvements in analysis and interpretation would therefore prove very useful for a faster and more thorough interpretation.
IDENTIFICATION OF SEA‐FLOOR SEDIMENTS USING UNDERWAY ACOUSTICS*
Authors: LI W. N. , SMITH D. TAYLOR 
Published: April 2006

AbstractLaboratory measurements, and a few in situ observations, show that saturated marine sediments have interdependent mechanical and acoustical properties, Acoustically, of particular importance are the acoustic impedance, velocity of sound and the sound attenuation coefficient of the sediment. The first two properties can be measured relatively easily from a surface ship; the measurement of attenuation however, is more problematical. It is suggested that this can be achieved by a quantitative treatment of the acoustic data collected during routine sub‐bottom profiling over a variable thickness of superficial sediments. In the assessment of four different sediment locations in the Irish Sea it was found that quantitative treatment of the acoustic signals yielded both a value of the attenuation coefficient as well as a measure of the frequency dependence of the attenuation. In addition a statistical analysis of the signal intensities seems to provide an indication of the relative roughness of the bottom and sub‐bottom interfaces. From the wide range of information provided the mechanical properties of the sea‐floor sediment may be estimated.
AERIAL RADIOMETRY OF EL ALAMEIN OILFIELD, EGYPT, U.A.R.*
Authors: EL SHAZLY E. M. , MESHREF W. M. , FOUAD K. M. , AMMAR A. A. , MELEIK M. L. 
Published: April 2006

AbstractTotal gamma airborne radiometric survey of El Alamein area in the Western Desert has been carried out by the Atomic Energy Establishment. The flight lines are directed north‐south with 500 m spacing, while the ground clearance is about 50 m. Superimposition of the radioactivity profiles over El Alamein Oilfield shows a general decrease of gamma radiation in the central part of the structure framed by zones of relatively higher values. The aerial radioactivity of El Alamein Oilfield is described and it is correlated with some reported radiometric characteristics of other oil bearing structures. The distribution of aeroradiometric measurements over El Alamein Oilfield and its environment has been found to be lognormal.
INTERPRÉTATION DIRECTE DES COURBES DE SONDAGE ÉLECTRIQUE ET LE PROBLÈME DE DIFFÉRENTS DISPOSITIFS DE MESURE *
Authors: SZARANIEC EDWARD 
Published: April 2006

ABSTRACTDirect interpretation methods of resistivity curves are discussed, which use the kernel function of the apparent resistivity. This function results from the consideration of the problem of diverse electrodes configurations.Several expressions for the determination of the kernel function of the potential from the kernel function of the apparent resistivity are given.
FIXED SOURCE SYSTEM IN A CONDUCTIVE ENVIRONMENT *
Authors: BEZVODA VÁCLAV 
Published: April 2006

ABSTRACTMeasuring systems with a fixed source fed with alternating current at sound frequency are used almost exclusively at the present time for a quick search for conductive zones in an environment with a high specific electrical resistivity. Owing to this fact it is useful to measure in a gradient configuration, i.e. to compare the quantities of the corresponding parameters of the field in two relatively close points oriented in the direction of the assumed change of the field. In this way we can obtain a suppression of the impact of the wider environment, since, in principle, we record the first derivative, i.e. the amount of the change only.The present article points out some possibilities of the application of the system with a fixed source in non‐magnetic environment with arbitrary resistivity.
SIGNAL ET BRUIT EN MAGNETOTELLURIQUE *
Authors: CHAIZE L. , LAVERGNE M. 
Published: April 2006

RÉSUMÉLes precédés classiques permettant de reconnaître le signal magnétotellurique à travers les bruits sont rappelé: en particulier les bruits ? enregistrement, ou ayant leur origine au voisinage immédiat des déecteurs, sont éiminés par les procédés classiques ? autoet intercorrélation. Ľ identification des bruits cohérents est beaucoup plus délicate: par exemple les pulsations provenant de sources de champs dont ľ uniformitéň atteint pas au moins une centaine de kilomètres en prospection pétrolière, un millier de kilomètres en physique du globe.Un grand nombre ? enregistrements des 5 composantes, Hx, Hy, Hz, Ex, Ey, du champ magnétotellurique ont été effectués en France à différentes périodes de ľ année, (a) dans des champs de source non uniformes au voisinage de lignes de traction électrifiées et de lignes de transport ?énergie, et (b) dans des zones à forte variation latérale de résistivité sur les flancs de grosses structures et au bord de la mer.Les moyens pour repérer la non‐uniformité sont étudiés. La mesure de la composante verticale des pulsations magnétiques est un bon procédé pour estimer ľ uniformité du champ. Si H vertical/H horizontal est inférieur à 10%, on peut pratiquement supppser ľ uniformité et appliquer les formules classiques de restitution des résistivités vraies. Si H vertical/H horizontal est supérieur à 10% il n'y a pas uniformité et il est difficile de savoir si la non‐uniformité est due à un champ de source non uniforme ou à des hétérogénéités ou anisotropies autour du point de mesure. Différents procédés permettant de lever cette indétermination sont donnés.La précision de la restitution des profondeurs en fonction de la précision des mesures des résistivités apparentes est étudée.
AN ELEGANT, UNIVERSAL NOMENCLATURE FOR ELECTROMAGNETIC MOVING SOURCE‐RECEIVER DIPOLE CONFIGURATIONS *
Authors: PARASNIS D. S. 
Published: April 2006

ABSTRACTThe transmitter and receiver coils and the line joining them in an electromagnetic moving source‐receiver system can, in principle, have an infinity of mutual orientations. Let the direction of a survey line (traverse direction) be x and let the vertical plane through it be the x‐z plane and let the z‐axis be a line in this plane perpendicular to the z‐axis, then the y‐axis of an orthogonal coordinate system is automatically determined. A definite coordinate system, dependent on the mutual coil orientation alone, and independent of the spatial direction of the survey line or alterations in it, is thus associated with each point. The geometry of a moving source‐receiver configuration is uniquely defined by specifying (i) the direction cosines a, b, c of the transmitter coil axis T, (2) the direction cosines d, e, f of the line L joining the transmitter and the receiver coils and (3) the direction cosines g, h, i of the receiver coil axis R. Hence a set of indices conveniently written as T a, b, c L d, e, f R g, h, i describes the geometry and also enables “reconstruction” of the system uniquely and without the risk of confusion inherent in such incomplete descriptions as “vertical coil system”, “horizontal coil system” etc. Degeneracy arises if the traverse direction is vertical. How this is overcome is described in the paper. To the above indices may be appended the indices T, the distance between T and R and v, the frequency.For example, the most common “horizontal coplanar coil system” has the indices T 001 L 100 R 001. An airborne wing‐tip system with coil axes in the flight direction is specified by T 100 L 010 R 100. Other examples are given in the paper. Maps and data sheets of moving source‐receiver systems should be marked with the appropriate set of indices.
PROSPECTING BY THE GEOTHERMIG METHOD*
Authors: KRČMÁŘ B. , MAŠÍN J. 
Published: April 2006

AbstractA high sensitivity thermometer using a thermistor sensing element was designed for practical measurements in the field.The most suitable procedures for the elimination of diurnal and seasonal variation of temperature, the influence of vegetation cover and of other effects were investigated.Positive results of geothermic measurements have been acquired on sulfide deposits. By far the most important results of geothermic measurements have been obtained in hydrogeological problems, e.g. the investigation of circulation of underground water. In the case of prospection for cold mineral waters the combination of geothermic measurements with gasometric analyses is very useful. As the classical domain for geothermic investigation, prospection for hot water is to be mentioned.
EARTH CRUST INVESTIGATION USING CONVERTED WAVES*
Authors: DRAGAŠEVIĆ T. 
Published: April 2006

AbstractThe conditions for creating and recording converted waves in the area of the Panonien basin are considered. Comparison between the characteristics of converted waves recorded in the field and characteristics of converted waves calculated for the model which approximately corresponds to lithophysical conditions of the area is made.The comparative interpretation of the crustal structure along the profile, using different types of waves, is given.
ON THE ELECTRICAL BEHAVIOUR OF A POLARIZABLE SAMPLE STUDIED BY THE NORMALIZED TIME‐INTEGRAL AND BALLISTIC METHODS*
Authors: FINZI‐CONTINI GIOVANNI 
Published: April 2006

AbstractIn this paper the experimental data obtained studying the decay of a sample of pisolitic bauxite both by a ballistic method and the normalized time‐integral procedure are compared.This comparison allowed me to note two peculiarities. First, the apparent capacitance of the sample, as well as its normalized time‐integral, seems to show a characteristic behaviour within the same interval of the charging time. Secondly, while the apparent capacitance plotted versus time (measured from the energization interruption instant) appears to assume values which seem to tend towards asymptotic value of the apparent capacitance, it is to be noted instead that in these circumstances the relative normalized time integral shows no tendency to reach any limiting value.
ETINCELEURS MULTIELECTRODES A HAUTE RESOLUTION*
Authors: CASSAND J. , LAVERGNE M. 
Published: April 2006

ResumeLes étinceleurs àélectrodes multiples, permettent ?améliorer considérablement la finesse de la sismique à haute resolution.Un pouvoir séparateur de ľordre de 2 mètres peut être obtenu jusqu'à une profondeur de l'ordre de 150 mètres avec des étinceleurs à 1000 joules, comportant quelques centaines ?électrodes. Plusieurs enregistrements sont présentéd.
SISMIQUE REFLEXION EN EAU PROFONDE*
Authors: CASSAND J. , FAIL J. P. , MONTADERT L. 
Published: April 2006

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‐graphie de grande reconnaissance.
DIRECT LOCATION OF OIL AND GAS BY THE SEISMIC REFLECTION METHOD*
Authors: PAN POH‐HSI , DE BREMAECKER J. CL. 
Published: April 2006

AbstractThe seismic velocity of sedimentary rocks is determined by the porosity, the velocity in the matrix and that in the fluid. The last two are known experimentally. The velocity can be measured from the surface. By applying the time average equation we can find the porosity. If the only difference at two points is the nature of the fluid in one layer, the ratio of the reflectivities of the layer at these points determines the nature of the fluid; this ratio is equal to the ratio of the amplitudes at these points. The size of the reservoir can then be found.The method can be applied to both oil exploration and production. It is more accurate in the latter case because more information is available than in the former case. The method is also more effective in developing discovered fields than the conventional method of relying only on the geological structural configurations.
AN ELECTRICAL RESISTIVITY PROFILE IN HAWAII WITH NOVEL ELEVATION CORRECTION*
Authors: ADAMS Wm. MANSFIELD 
Published: April 2006

AbstractIn order to locate relatively optimum sites for drilling exploratory holes for fresh water, an electrical resistivity survey was conducted along the new Mahukona‐Kawaihae Road on the west flank of the Kohala Mountain. Two resistivity soundings made at the same stations, using the Schlumberger electrode configuration, determined an a spacing of 275 feet for horizontal profiling with the Wenner array.The correlation coefficient of the elevation to profile data was 0.41. A procedure for removing elevation effect from observed apparent resistivity was developed. Based on the reduced resistivity profile, four relatively optimum sites for additional exploration, such as by drilling, are specified. There is no specific interpretation of the data that can definitely indicate the occurrence of large underground reservoirs of fresh water anywhere along the profile. This is because the interpretation of horizontal profiling data is essentially relative and not absolute.
LA RESISTIVITE APPARENTE COMME TRANSFORMATION LINEAIRE DU POTENTIEL ET LA TRANSFORMATION INVERSE*
Authors: SZARANIEC EDWARD 
Published: April 2006

AbstractThe apparent resistivity is considered as a linear transformation of the potential by an operator in the form of an infinite matrix A. The inverse transformation expresses the potential as a function of the apparent resistivity or of the difference of potentials. It is found by calculation of the inverse matrix‐1A. The relation between apparent resistivities for different arrays is expressed as a product of transformations.
CORRELATION OPTIQUE EN LUMIERE COHERENTE*
Authors: FONTANEL A. , GRAU G. 
Published: April 2006

AbstractFontanel, A., G. Grau, 1971, Corrélation optique en lumière cohérente, Geophysical Prospecting 19, 98–117.This paper describes a general bidimensional two‐step method of correlation (or convolution) making use of the theory of holography.In the first step the light diffracted by one of the two plane transparent objects to be correlated interferes with the light diffracted by the other one. The hologram thus generated is photographed in the focal image plane of a convergent lens. Owing to the quadratic detection property of the photographic emulsion, the square of the modulus of the product of the spectra of the two objects considered is recorded on the photographic plate.In the second step the convolution product of the two objects appears when the hologram is illuminated with a beam of coherent light.In its geophysical application this optical method of convolution makes it easy for us to obtain the autocorrelogram of a seismic cross‐section. This method also makes it possible to correlate each of the seismic traces by special precalculated optically‐recorded filters.
THE INFLUENCE OF INDUSTRIAL STRAY CURRENTS ON THE MEASUREMENT OF EARTH POTENTIALS AND THEIR ELIMINATION*
Authors: FRÖHLICH R. K. 
Published: April 2006

AbstractSimultaneous observations of electrical earth‐potentials along parallel measuring lines offer a simple but useful method to study telluric and stray‐current potentials. Different correlation‐factors between the records of both observation points can help to separate telluric from industrial stray‐current potentials. A method is suggested to eliminate disturbing impulses of stray currents from continuous telluric current recordings as those made at observatories.The influence of stray currents can also be eliminated from potential readings of an artificial current as applied in geoelectric measurements with the four‐point‐method. The elimination is possible by a simultaneous observation of the stray‐current potentials on an equipotential line of the artificially generated field. The recording examples show an appreciable improvement of the signal‐noise ratio without increase in the current. The method is useful for geoelectrical prospecting in areas which are contaminated by industrial noise.
A CONTROL OF TWO‐DIMENSIONAL MAGNETIC INTERPRETATION BY THREE‐DIMENSIONAL MODEL BODY ANOMALIES*
Authors: LEHMANN HANS‐JÜRGEN 
Published: April 2006

AbstractIn magnetic routine interpretation the comparison of two‐dimensional model curves with measured magnetic anomalies is widely used for an approximate evaluation of the position and depth of magnetic models.Before starting an interpretation of a survey by means of two‐dimensional models, it is very useful to have an idea of the shape of anomalies caused by extended but finite bodies, taking into account various strike directions: Three sets of anomalies of thin plates (horizontal length 19, downward length 9, width 1) dipping 30°, 60°, and 90° resp. for various strike directions and an inclination of 20° were computed. Some of these anomalies, e.g. those with nearly N‐S strike direction look rather complicated, and at the first glance one would not expect that they are caused by such simple bodies.Several profiles crossing the computed anomalies perpendicularly were interpreted two‐dimensionally. For less extended anomalies the depths determined for the top of the plates are 10‐20% too small, the magnetization amounts to 50–75 % of the value of the finite bodies. The interpretation of the profiles covering more extended anomalies gave very accurately the same values for the position, depth and magnetization for the two‐dimensional body as for the original three‐dimensional model.Anomalies of vertical prisms with varying extensions in the y‐direction were computed. Their differences in amplitude and in the distance maximum‐minimum show that interpretation of short anomalies by two‐dimensional methods yields depth errors of up to 20 percent.To see the possibilities of the separation of superimposed anomalies dike anomalies were added to the anomaly of a broad body in great depth and several attempts were made to interpret parts of the composite anomalies. The interpreted bodies lie too deep. In complicated cases the depth values can have large errors, but experienced interpreters should be able to keep the errors in the range of one third of the depth values.
CONTRIBUTION TO SIGNAL BY ELEMENTS OF THIN VERTICAL CONDUCTING VEIN IN DIPOLAR EM SYSTEMS*
Authors: ROY A. , JAIN SHEEL C. 
Published: April 2006

ABSTRACTAs an extension of the eddy current pattern computed by Koefoed and Kegge (1968) for a thin vertical infinitely‐conducting half‐plate in presence of oscillating magnetic dipoles, this paper computes the contribution to the (electro‐) magnetic anomaly at the receiver by each element of the vein separately. Twelve contour diagrams for such elemental contributions are presented as samples. Two points of general interest stand out: (1) The contributions from different portions of the vein are not all of one sign; the contribution from one part may cancel that from another; and (2) The portion of the vein nearest to the transmitter‐receiver system does not necessarily make the largest contribution to the total measured signal.
PREDICTION ERROR FILTERS, WHITE NOISE AND ORTHOGONAL COORDINATES*
Authors: DOUZE E. J. 
Published: April 2006

AbstractOptimum filters can be computed using orthogonal coordinates obtained from the eigenvalues and eigenvectors of the autocorrelation matrix. The method is used to obtain unit distance prediction error filters. The output of a unit distance prediction error filter when applied to the input wavelet is an impulse at zero time. The effect on the output of added white noise is easily obtained using the approach through the orthogonal coordinates. The added white noise results in output wavelets which are no longer impulses at zero time. The decrease in time resolution gives a filter that does not increase undesirable high frequency noise as much as filters computed without white noise.Orthogonal coordinates with little signal energy can be omitted from the filter computation resulting in output wavelets resembling those computed using added white noise.
REVIEW ON THE BASIC THEORETICAL ASSUMPTIONS IN SEISMIC DIGITAL FILTERING*
Authors: FINETTI I. , NICOLICH R. , SANCIN S. 
Published: April 2006

AbstractA review of the most significant mathematical properties of digital operators and an introduction to their important applications to seismic digital filtering is given.Basic definitions in the time‐series field and the principles of digital filtering are introduced starting from the Z‐transform domain.Predictive decomposition for stationary stochastic processes and inverse operators are also discussed.Applications of digital filtering to seismic signal concern the predictive deconvolution, characteristics of dispersive and recursive operators, matched filters, and multichannel operators.A brief discussion on frequency, wave number, and velocity filtering phylosophy is given at the end of the paper.