bluuebunny/crossref_metadata_2025_split huggingface dataset:
ON THE EFFECT OF THE TANK WALL MATERIAL IN GEOELECTRICAL MODEL EXPERIMENTS
Authors: GOUDSWAARD W. 
Published: April 2006

AbstractThe effect of the composition of the tank walls on apparent resistivity determinations made in model experiments has been investigated for the two extreme cases of an insulating and a perfectly conducting tank wall: The resulting errors have been determined both by calculation and by experiment.Experiments are described which demonstrate that the magnitude of the effect can be considerably reduced by specially constructed tank walls.
MANGANESE ORE OF SOUTH‐INDIA AND ITS MAGNETIC PROPERTIES *)
Authors: BHIMASANKARAM V. L. S. , RAO B. S. R. 
Published: April 2006

AbstractThe Kodur Manganese belt has been surveyed with a vertical magnetometer. It was generally observed that both high positive and negative anomalies were associated with some of the existing ore bodies. Other large manganese ore deposits gave little or no magnetic anomalies. Further it was observed that both types of manganese ore deposits giving rise to large and little magnetic anomalies, contained similar percentages of manganese and iron. In view of these discrepancies, an extensive study of the magnetic properties of these manganese ores was taken up. The results of these measurements showed that the susceptibilities of the manganese ore samples collected vary over a wide range.It was observed that the high susceptibilities are associated with samples containing manganmagnetite and vredenburgite, whereas samples rich in psilomelane and pyrolusite possess low susceptibilities. From the chemical analysis, normative values of manganmagnetite and vredenburgite–with a general formula of (Mn.Fe)3O4– were calculated and a linear relationship could be established between these normative values and susceptibilities.
RICHTCHARAKTERISTIKEN VON GEOPHONGRUPPEN MIT BERÜCKSICHTIGUNG DER EINZELCHARAKTERISTIKEN*
Authors: SCHILLEMEIT JOST , CELMINŠ AIVARS 
Published: April 2006

AbstractThe directional sensitivities of an array of geophones depend as much on the size of the array as on the directional sensitivities of the single geophones forming the array. In a former paper (Celminš 1956) the effect of the size of the array was investigated. In addition to this the influence of the directional sensitivities of the individual geophones on the sensitivities of an array of geophones is investigated here.In δ 2 some general formulae for the directional sensitivities are derived. In addition the directional sensitivities of a single geophone according to P‐ and S‐waves are investigated (δ3 and δ4). In δ5 the'directional sensitivities for the most important cases of arrays of parallel geophones are computed. The results of the computation (shown in fig. 4 and 5) give an idea of the types of directional sensitivities which occur in the use of geophone arrays.
QUELQUES RECENTS ASPECTS DU FORAGE SISMIQUE*
Authors: DUFOUR J. , DEGORSE A. 
Published: April 2006

ABSTRACTThe shothole drilling industry has had new developments and its evolution is tied to several causes. First, more and more difficult and varied formations have to be drilled. Second, new procedures have to be used in desert regions recently open to prospecting. Finally, modifications of the seismic methods themselves (multiplication of the charges, shallow holes, etc.) lead the driller to use more economical and lighter tools. In this paper the following types of drilling equipment are described: the Mouton Delmag for spudding through pebbles and loose gravels; a mud mixing water truck and an extensible mast used for drilling multiple medium depth holes through caving sands; a compressed air‐drill for regions where the water supply is practically nil; rock drills, such as a Wagon‐Jack and the Warsop hammer, for multiple shallow holes in various formations.
AMMONIUM NITRATE: ECONOMY BLASTING AGENT FOR OIL EXPLORATION*
Authors: HALL T. O. , MARTIN J. 
Published: April 2006

AbstractMajor savings for operators of seismic parties have been achieved by the use of prilled ammonium nitrate as a substitute for gelatin dynamite in areas where shot holes are dry. Pound for pound, the prills appear to have the same energy yield as 60% gelatin dynamite, and some improvement of records has been noted where prills are used. Safety problems are less with ammonium nitrate than with dynamite, and the development of efficient field handling techniques prevents the loss of production.
THE FIELD OF A D. C. ELEMENT, APPLIED TO GONDUCTIVELY ENERGIZED PENCILFORMED ORE BODIES
Authors: OVERHOLT K. J. 
Published: April 2006

AbstractThe electric and magnetic field of a direct‐current element, embedded in a space consisting of two halfspaces differing in conductivity and permeability, is given in a form suitable for integration along a cable. From these formulae is obtained the field when one end of a D.C. cable is grounded in a highly conducting, pencilformed ore body, considered as a line electrode with uniform current leakage. Numerical examples are given for a horizontal line electrode. The formulae should be useful as a first approximation to the A.C. case. The validity of this is shortly discussed.
DESIGN CONSIDERATIONS OF A BORE‐HOLE GRAVIMETER
Authors: DOLBEAR D. W. N. 
Published: April 2006

AbstractDue weight must be given to three factors (1) its purpose, (2) the limitations imposed by nature, industry and environment, (3) the effect of errors in auxiliary measurements. Together the last two factors give an estimate of the accuracy which can be achieved. If this is sufficient for the instrument to fulfil its purpose design and construction can proceed. If it is not, a detailed survey of the last two factors is necessary in order to estimate the research effort that will be required when directed into the most effective channels. If the project is considered worth the effort it can proceed. These factors are discussed in relation to a borehole gravimeter. It is shown that the purpose will be served only if the accuracy is comparable with the best surface gravimeters. Borehole versions of some surface instruments are considered and it is concluded that none is suitable without considerable modifications. A successful borehole gravimeter is likely to be a completely new instrument.
OPTICAL ANALOGUE OF GRAVITY AND MAGNETIC FIELDS
Authors: ROY AMALENDU 
Published: April 2006

AbstractGravity anomalies due to given mass distributions have been determined by model optical experiments, which utilise the fact that both the light intensity and the gravitational field due to point sources obey the Inverse Square law. The technique is somewhat different from that used by Gerrard et al (1957), and the results seem to be more accurate (maximum discrepancy 2 percent). The applicability of the anology for the determination of magnetostatic fields is also pointed out.
THE RESPONSE OF VELOCITY‐SENSITIVE WELL GEOPHONES *
Authors: DENNISON A. T. 
Published: April 2006

AbstractThe factors affecting the response of a velocity‐sensitive well geophone are discussed and it is shown that the geophone movement in response to a seismic pulse is primarily due to the pressure difference between its ends. Several practical examples are calculated to show that the first arrival waveform recorded by a geophone depends on the distance from an interface and that these changes in recorded waveform may give errors of up to 3 msec in well‐velocity surveys. These errors may be minimised by using pressure geophones or by avoiding measurements at geological interfaces.
ATTACKING THE PROBLEMS OF THE SYNTHETIC SEISMOGRAM
Authors: ANSTEY N. A. 
Published: April 2006

AbstractThe four problems considered are the definition and simulation of the filtering effects which occur in the earth between the explosive and the case of the geophone, the problem of errors in the time scale of the synthetic record, the simulation of multiple reflection effects, and the difficulty of finding a representative comparison trace on the field record. A partial solution to the first of these is offered by Siran, examples of whose operation are presented. A method of assessing allowable errors in the time scale is discussed. Multiple reflections may be introduced by the preparation of multiple‐corrected reflection‐coefficient logs on a digital computer such as the IBM 709. The particular problems of multiple reflections from the base of the weathered layer (including “ghost” reflections) are discussed. The preparation of a “composite” trace is shown to be a partial solution to the problem of the comparison with the field record.
ON THE OCCURRENCE OF LOW RESISTIVITY GEOLOGICAL CONDUCTORS
Authors: BOSSCHART R. A. 
Published: April 2006

AbstractLaboratory investigation has shown that the resistivity of massive sulphide ores at specimen dimensions is of the order of 0–10 ohmcm. Several writers, on the basis of field results obtained with various electromagnetic methods, deny the possibility that natural orebodies could have correspondingly low resistivities. The question is of interest, since such conductors, because of their small imaginary response, would be undetectable by electromagnetic methods measuring only imaginary components or phase shifts.In the present paper anomalies obtained with the Loop‐Frame electromagnetic method on massive sulphide bodies in different parts of Canada are discussed. It is shown, by means of model experiments, that the conductors all have very low resistivities which, where the effective thickness can be determined, appear to correspond to the order of magnitude of specimen resistivity. It is demonstrated that confusion of the total width of a conductor with its effective thickness may lead to erronous resistivity determinations.
QUELQUES EXEMPLES D'UTILISATION DES FILMS SYNTHETIQUES*
Authors: DELAPLANCHE J. 
Published: April 2006

AbstractThe synthetic seismogram is a geophysical instrument. Examples taken from several areas are presented in order to define this tool and to show how it may be utilised in all stages of the prospection.The synthetic seismogram translates the stratigraphic information obtained from exploration wells into seismic terms; it therefore deserves to be taken into consideration when choosing the methods to be employed for solving a given problem.The synthetic seismogram enables one to know the limitations imposed by the reflecting power of the different subsurface layers. The knowledge of these limitations, combined with an understanding of the difficulties inherent in the surface conditions, helps to determine the frame in which the survey and the interpretation must be set.During the actual survey the synthetic seismogram illuminates somehow the work of the seismologist. It is a reference base which defines the correlation criteria which permit him to analize the real traces and, at the same time, to increase their resolving power.The methods of utilisation are examined both with respect to the field work (attempts to determine the technique to be used in any area by reference to the synthetic traces; determination of the volume control; choice of filters) and in the field of interpretation (identification and picking of reflections; analysis of the signals in order to obtain stratigraphic information from them; study of the character of reflections on a regional scale and density of the synthetic seismograms to be made in any region; re‐evaluation of the information contained in old seismic records).
WAVE‐FRONT DIAGRAMS FROM UPHOLE SHOOTING*
Authors: MEISSNER R. 
Published: April 2006

AbstractUphole shooting during a reflection or refraction survey provides additional information about the velocities within the weathered layer if recorded with a complete spread of geophones on the surface. Wave‐front diagrams can be constructed which give a genuine picture of the wave paths in the subsurface. Their construction is based on the assumption that the travel time from a shot in the hole to a geophone on the surface is the same as that from a fictitious shot on the surface to a fictitious geophone in the subsurface.
LA RADIOMÉTRIE AÉROPORTÉE, OUTIL D'EXPLORATION GÉOLOGIQUE STRUCTURALE*
Authors: GIRET R. 
Published: April 2006

AbstractThis paper gives the results of an airborne radiometric survey flown in France over an area of 1,700 km2 at 150 m. above ground, with parallel north‐south profiles 1 kilometre apart. Besides uranium indications discovered or recovered, this survey shows a close correlation between isorad and geological maps. The southern granitic zone is more radioactive than the northern gneissic one, with a constant step on the boundary. In the northern zone granitic intrusions have high radioactivity, and isorad contours are right on the boundaries of the main granitic units. In addition, the radiometric map shows the connections between these batholith roots and probable new satellite outcrops not shown on the geological map. Such a radiometric map is a help towards completing the geological map, and gives indications regarding probable structural connections between different granites.The detailed survey of an anomaly discovered during the previous reconnaissance survey is given as another example. It was flown twice, with an aircraft at 75 m elevation with profiles 250 m apart, and with a helicopter at 35 m elevation with profiles 50 m apart. In this area of the main Marche fault, granulites in the south and gneisses in the north have low radioactivity, and the central shearing zone also. But, on both sides of this shearing zone, two crushed areas have high radioactivity, and uranium indications. The geological survey of the northern crushed gneisses area shows small granitic intrusions linked with the radioactive anomalies. These intrusions were unknown until they were discovered with the help of this map. Some mineral indications are connected with them.
EARTH TILTS AND THE FLOW OF OIL WELLS*
Authors: TOMASCHEK R. K. A. 
Published: April 2006

AbstractIt has been discovered that certain flowing oilwells in the Eakring area (Nottinghamshire, England), which have not otherwise been disturbed, show distinct annual variations in the flow of total fluid. There appears to be a definite connection between these variations and the seasonal movements of the earth's crustal layers as evidenced by observations of the tilts of the earth's surface. The investigation has been extended further to show that a similar relation exists between the earth tilts and the production of a whole oilfield which has not been disturbed unduly by outside influences.A correlation has also been established between the earth tilt observations and the periodicity of shallow earthquakes.
THE APPLICATION OF ELECTRONIC COMPUTERS TO THE CALCULATION OF EFFECTIVE MAGNETISATION
Authors: VOGEL ANDREAS 
Published: April 2006

SUMMARYThe normal procedure in calculating the effective induced magnetisation of bodies is to introduce the demagnetisation factor. The theory of calculating the demagnetisation factor is however restricted to bodies of 2nd degree surface lying in a homogeneous field i.e. homogeneously magnetised bodies. All other bodies have to be approximated.Here, the method is based on iterative calculation of magnetisation fields, which makes it possible to calculate the effective magnetisation of any bodies, when the distribution of the inducing field and susceptibility are known.
A LABORATORY STUDY OF STREAMING POTENTIALS*
Authors: AHMAD MOID UDDIN 
Published: April 2006

ABSTRACTThe magnitude of the streaming potential due to the passage of a liquid through a porous medium is examined, under conditions similar to those found in an aquifer under the action of a pumping well. Three models simulate flow in channels, conduits, and unconfined aquifers for several grain sizes of sands and for several resistivities of fluids. The ratio of the streaming potential to the pressure difference is constant for a selected sand and fluid, decreases as grain size increases, is essentially independent of the geometry of the flow, increases slightly as the permeability decreases, and decreases as the salt concentration increases. Extremely low streaming potentials can be expected near a pumping well.
PROPRIETES DE FILTRAGE DES FORMULES UTILISEES POUR LA TRANSFORMATION DES CARTES GRAVIMETRIQUES*
Authors: NAUDY HENRI 
Published: April 2006

RESUMEPour caractériser les anomalies de la carte initiate et de la carte transformeé, on définit des indices de netteté désingés respectivement par I0 et I et on étudie le rapport I/I0 pour diverses formules appliquées à trois anomalies typiques (sphère, anticlinal, faille). Les courbes obtenues permettent d'introduire, par analogie avec les circuits électriques, des notions telles que profondeur de coupure et pente.
VISCOELASTIC PROPERTIES OF THE STANDARD LINEAR SOLID*
Authors: MEIDAV TSVI 
Published: April 2006

ABSTRACTThis study is an attempt to find a phenomenological model which will behave in a manner similar to that of common earth materials in regard to the dependence of attenuation and phase velocity on frequency.An analysis of two commonly employed rheological models, Maxwell's and Kelvin‐Voigt's and their variants, is presented indicating that these models are too simple to conform phenomenologically to the behavior of rocks. It is shown that a linear combination of the Maxwell and Kelvin‐Voigt models, known as the standard linear solid, comes closer to giving an adequate description of the behavior of some earth materials, than either one of the two models.A method of determining the viscoelastic constants of a solid is presented provided that its attenuation and dispersion curves are known. The viscoelastic constants (relaxation times and/or viscosity coefficients) of the solid are determined by superimposing the experimental curves on master curves, and reading the constants off the theoretical curves.An analysis of published experimental data is presented, indicating that the present model is capable of accounting for at least some attenuation and dispersion phenomena.
GRATICULES FOR THE COMPLETE DETERMINATION OF THE MAGNETIC FIELD OF HOMOGENEOUSLY MAGNETIZED CYLINDRICAL BODIES WITH ARBITRARY CROSS SECTION AND FINITE LATERAL EXTENSION*
Authors: HELBIG KLAUS 
Published: April 2006

ABSTRACTGraticules are known for the calculation of the magnetic field of homogeneously magnetized “two‐dimensional” structures. For bodies whose lateral dimensions are comparable with the dimensions of the cross section and/or the distance between the point of observation and the structure, these graticules allow an approximative computation of the field in the plane of symmetry only. The degree of approximation can be improved by means of end corrections, but the amount of work involved increases rapidly. Moreover, even with end corrections the applicability of the graticules is still restricted to cases of rather simple geometry.In this paper, a set of graticules is proposed which already incorporates all end corrections. The set consists of three graticules, and it can be shown that at any point of observation lying outside the body each graticule needs be applied once only in order to calculate any component of the magnetic field produced by a homogeneously magnetized cylinder of arbitrary cross section, finite lateral extension and arbitrary spatial orientation.Curves and tables have been prepared, which allow the construction of the graticules under consideration. The application is illustrated by a hypothetical example. Possibilities for further improvements of the method are discussed.
ÜBER DIE DIMENSIONIERUNG UND DAS VERHALTEN VON REGELKREISEN IM SEISMISCHEN VERSTÄRKER*
Authors: WACHHOLZ HELMUT , WEISSENSTEINER KARL 
Published: April 2006

AbstractThe purpose of the automatic gain control in seismic amplifiers is to balance the slow decrease of the signal in such a manner that its energy does not exceed the capacity of the recording system. At the same time the interesting seismic content of the signal has to be preserved as undistortedly as possible. At first, the technical data of AGC circuits are calculated. The characteristic curves of circuits with one, two, and three time constants are computed. In circuits with two and more time constants an oscillating of the AGC is possible. In order to guarantee aperiodic operation, the ratio of the time constants must not fall below a certain value. As long as these technical conditions are complied with, the free choice of the largest time constant remains open and can be accommodated to the geophysical conditions.From the endeavour to balance the slow decrease of the signal as well as possible, an upper limit for the choice of the time constants can be derived. A lower limit is obtained from the condition that the seismic content of the signal has to be preserved. The determinant time constant should lie between the two limits and differ from them as much as possible.Finally, the problem of the amplifier “squeezed” by energy pulses is touched.
INFLUENCE DE LA LARGEUR DU PAS D'ECHANTILLONNAGE DU CAROTTAGE CONTINU DE VITESSES SUR LES SISMOGRAMMES SYNTHETIQUES A MULTIPLES*
Authors: BOIS P. , HEMON CH. , MARESCHAL N. 
Published: April 2006

AbstractAttenuation caused by transmission is known to be the greater the closer the samples are taken together. As a result, the amplitudes of seismograms with multiple reflections can be expected to be negligible within a more or less brief time interval, as is the case for seismograms without multiple reflections with attenuation. This paper examines the process by which multiple reflections regenerate these greatly attenuated reflections. It is also ascertained that a sampling interval of one ms for continuous velocity logs is valid for any survey. For economic reasons, we recommend the selection of a larger interval without, however, overdoing things and thus losing too much information.