bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiratory atopic disease, Ascaris‐immunoglobulin E and tuberculin testing in urban South African children
Authors: Obihara C. C. , Beyers N. , Gie R. P. , Hoekstra M. O. , Fincham J. E. , Marais B. J. , Lombard C. J. , Dini L. A. , Kimpen J. L. L.
Published: April 2006

Background
Epidemiological relation of intestinal helminth infection and atopic disease, both associated with a T‐helper (Th) 2 immune response, is controversial, as it has been reported that helminth infection may either suppress or pre‐dispose to atopic disease. This relation has not been tested in an area with a high burden of Mycobacterium tuberculosis (MTB) infection, a known Th1‐stimulating infection.

Objective
To study the association of intestinal helminth infection and atopic disease in a community where helminth infection is endemic and MTB infection is high.

Methods
Three‐hundred and fifty‐nine randomly selected children aged 6–14 years from a poor urban suburb were tested with allergy questionnaire, skin prick test (SPT) to common aeroallergens, Ascaris‐specific IgE (Ascaris‐sIgE), fecal examination for pathogenic intestinal helminths and tuberculin skin testing (TST). Histamine bronchoprovocation was tested in the group of children aged 10 years and older. Results were corrected for demographic variables, socioeconomic status, parental allergy, environmental tobacco smoke (ETS) exposure in the household, recent anthelminthic treatment and for clustering in the sampling unit.

Results
Ascaris‐sIgE was elevated in 48% of children, Ascaris eggs were found in 15% and TST was positive in 53%. Children with elevated Ascaris‐sIgE had significantly increased risk of positive SPT to aeroallergens, particularly house dust mite, atopic asthma (ever and recent), atopic rhinitis (ever and recent) and increased atopy‐related bronchial hyper‐responsiveness. In children with negative TST (<10 mm), elevated Ascaris‐sIgE was associated with significantly increased risk of atopic symptoms (adjusted odds ratio (ORadj) 6.5; 95% confidence interval (CI) 1.9–22.4), whereas in those with positive TST (10 mm) this association disappeared (ORadj 0.96; 95% CI 0.4–2.8).

Conclusions
These results suggest that immune response to Ascaris (Ascaris‐sIgE) may be a risk factor of atopic disease in populations exposed to mild Ascaris infection and that MTB infection may be protective against this risk, probably by stimulation of anti‐inflammatory networks.
REFLEXIONS MULTIPLES OBLIQUES*
Authors: RICHARD H.
Published: April 2006

Abstract

After a short introduction, some examples of obliques multiple reflexions are treated and possible solutions given.
POSSIBILITIES OF CONSTRUCTING TRUE RAY PATHS IN REFLECTION SEISMIC INTERPRETATION*
Authors: DÜRBAUM H.
Published: April 2006

Abstract

Investigations into reflection seismic on the salt structure of Heide raised the following questions:

How can the different directions of trend of a series of layers be established?

How are the contour maps of reflecting horizons to be constructed if there is no general trend of the layers?

To answer these questions, the case of the subsoil consisting of a series of layers with plane reflecting beds and constant layer‐velocities is treated strictly. The strike lines of the reflecting planes may be at any angle whatever. However, formulas for constructing contour maps of the reflecting planes have been derived. With these formulas, the problem quoted under 1) has also been solved.

The construction of contour maps is given.

For special cases, formulas are obtained which have already been proved by others.
THE INITIAL ADJUSTMENTS OF VERTICAL VARIOMETERS*
Authors: BRUCKSHAW J. M.
Published: April 2006

Abstract

Using a comprehensive theory of the vertical force variometer, it is shown that the mean of the two readings taken in azimuths 180 degrees apart only eliminates the error of misorientation and of inclination of the knife edge if these factors are sufficiently small. The necessary accuracy in the 180 degree rotation and in the readjustment of the levels are investigated and a practical test is developed to allow the initial adjustments to be determined. Finally, a brief description of a new variometer tripod is given.
AN ATTEMPT TO INTERPRET THE GRAVIMETRIC MAP OF THE NORTHERN PART OF THE MOROCCAN BASIN OF GHARB. MAPS OF RESIDUAL ANOMALY AND FIRST DERIVATIVE*
Authors:   SOCIETE CHERIFIENNE DES PETROLES, AYNARD C.
Published: April 2006

Abstract

The main features of the gravimetric map of the Gharb can be related to the shape of the basement, covered by cretaceous and miocene layers, with a total maximum thickness of 13,000 feet. For the interpretation of local features, in the northern part of the basin, first a regional anomaly has been drawn, then the map of the first derivative has been established.

Both maps are compared with geological maps and seismic and electrical surveys. The results are the following:

As for method, the advantages and limitations of both processes are outlined.

As for geological interpretation, it is suggested that most of the local features of the gravimetric map are due to the preriffan tectonics.
A PRACTICAL EXAMPLE OF AN ANISOTROPIC VELOCITY‐LAYER*
Authors: HAGEDOORN J. G.
Published: April 2006

Abstract

The results obtained from a number of seismic velocity well‐logging surveys and adjacent refraction sections are compared. The velocities derived by these two methods for a certain layer are found to differ appreciably. This is shown by presenting the time‐depth relations of the well‐surveys and the time‐d stance relations of the refraction sections at three locations, plotted on graphs with sloping depth‐ and distance axes.
ON THE PROPAGATION OF SEISMIC WAVES IN A SOLID BODY WITH ELASTIC AFTERWORKING*
Authors: MENZEL H.
Published: April 2006

Abstract

The different equations of elasticity concerning the departure of the behaviour of rocks from perfect elasticity are discussed. The theory of elastic afterworking and its significance for the propagation of elastic waves is studied in detail. It is found that this theory does not explain the observations on seismic waves in exploration geophysics so well as the theory of viscoelasticity suggested by Ricker.
SUR UNE METHODE ANALYTIQUE DE CALCUL DE L'ANOMALIE REGIONALE*
Authors: BARANOV V.
Published: April 2006

Abstract

The common notion, that the regional anomaly must be as regular as possible, can be translated into mathematical language by requiring that the regional anomaly shall be represented, over a not too large area, by a surface of the second or of the third degree. The residual anomaly is commonly defined by the requirement that its horizontal dimensions must be as small as possible. This implies that also its amplitude should be small. This requirement may be moulded into a mathematical form by stating that the square of the difference between the Bouguer anomaly and the regional anomaly, integrated over a certain area, must be a minimum. On these two definitions an analytic method is based for deriving the regional anomaly. Practical computation procedures are presented.
A TEST ON ELASTIC ANISOTROPY MEASUREMENT AT BERRIANE (North Sahara)*
Authors: CHOLET JACQUES , RICHARD HENRI
Published: April 2006

Abstract

The geophysicists who attempted to evaluate elastic anisotropy of some bedded formations most often gave but little information about recording and interpretating the measurements.

May be they did not lay enough stress on the fact that any determination of the anisotropy factor is a critical operation and that, to have some certainty. it must be made under good conditions and then discussed.

Due to the very favourable conditions offered: undisturbed tectonics and topography, relatively regular series the Berriane district in Northern Sahara, is rather well suited to accurate measurements and to an anisotropy study down to 1,250 meters. Since measurements have been carried out in the wildcat drilled at Berriane by S. N. Repal, it seems interesting to communicate the results obtained and to discuss them according to the influence of high velocity layers.

It can be noted that in the clay and sand series which have been investigated, anisotropy coefficient amounts to 1.09 or so.

To conclude, it seems desirable that determinations made by numerous operators should allow a more accurate knowledge of the anisotropy factor in the main types of rocks.
RAPPORTEUR POUR LA CONSTRUCTION RAPIDE DU RAYON REFRACTE*
Authors: SCHOEFFLER J. , DIEMER E.
Published: April 2006

Abstract

In this paper we describe a protractor which provides a very simple method of constructing refracted rays in a vertical plane. Another advantage of this apparatus is that it can be made locally in any computing office.
A RATIONAL APPROACH TO THE DESIGN OF ELECTRICAL FILTERS AND OF SHOT‐HOLE AND GEOPHONE PATTERNS IN SEISMIC REFLECTION PROSPECTING*
Authors: MUIR F. , HALES F. W.
Published: April 2006

The authors develop an optimum filtering theory for seismic reflection recording. A criterion of record improvement is applied to a mathematical model consisting of a set of wavelets superimposed on a random noise backgruond. This leads to the design of electrical filters and geophone and shot‐hole patterns with optimum filtering characteristics.
GRAVITY VARIATIONS IN SURVEYS ACROSS GEOLOGICAL BOUNDARIES *
Authors: COL‐L‐EY G. C.
Published: April 2006

The paper discusses the variations of Elevation Correction Factors (E.C.F.) across various stratigraphical and structural occurrences with particular reference to the dipping bed, fault and horst. Graphs are prepared giving E.C.F. variations for various angles of dip and a method is suggested for application in the field. Errors in the linear variation that is commonly used for small angles of dip are discussed.

The second part of the paper consists of the application to interpretation of (I) Change of gravity dip and (2) The gravity inversion. It is shown how from a gravity map the dip, position of outcrop and thickness of a dipping bed can be determined. The last part shows how anticlines can give rise to negative anomalies and that in the direction of dip similar structures can at one point have no surface expression and afterwards invert to positive anomalies. The danger of attempting to predict the size of structures in such areas is emphasised.
INSTRUMENTAL DISTORTION AND THE SEISMIC RECORD*
Authors: ANSTEY N. A.
Published: April 2006

Abstract

This paper is presented to the geophysicist concerned with the interpretation of seismic records. Those instrumental factors which can affect the validity or accuracy of the records are detailed. Inferences are drawn relating to the picking, timing and grading of reflections, and the shooting of records in the field.
A RAPID METHOD OF DETERMINING THE FORM OF A SEISMIC*
Authors: TARRANT L. H.
Published: April 2006

A set of refraction line arrival times can be readily converted into a set of delay‐times providing the refractor velocity is known. If we then subtract the delay‐time at the shot‐point end, we arrive at a set of delay‐times representing the refractor depths at the receiving end. This paper is concerned with the conversion of such a set of delay‐times into a profile of the refractor.

The method is semi‐graphical and very easy to apply. For each geophone station an arc of a circle is constructed, such that the envelope of the series of arcs represents the surface of the refractor. While the method is not quite exact, especially when the dips are large, it is of particular value in allowing for the effects of varying dips upon the offset distance. The method treats the overburden above the refractor as if it were of uniform velocity.
THE USE OF INTEGRATORS HELPS COMPUTING TERRAIN CORRECTIONS IN GRAVIMETRY*
Authors: MONNET C.
Published: April 2006

A special method is described for calculating the terrain correction of the observed gravity data. The ground around each station is divided into a certain number of sectors and a special integral of the topographical section is calculated along each dividing radius.

A computation chart has been constructed, by means of which the integration is reduced to the measurement of an area or of the first moment of an area. A planimeter or alternatively an integrator have to be used for this measurement.

The article shows how to trace the computation chart for the use of the first moment method.

This method has been extensively tested by the author and on the basis of this experience it has been found that the method affords a considerable speeding up of the calculation and is, in this respect, superior to the other methods that have been used so far for calculating the terrain correction.

The problem of the accuracy of the integrator is also discussed in this paper.
THE ELECTRICAL RESISTIVITY OF SOME SULPHIDE AND OXIDE MINERALS AND THEIR ORES*
Authors: PARASNIS D. S.
Published: April 2006

The electrical resistivity of 60 pyrite, 31 chalcopyrite, 42 pyrrhotite, 8 arsenopyrite and löllingite, 6 cobaltite, 15 galena, 13 zincblende, 26 haematite, 46 magnetite, 16 various manganese minerals, 23 complex ores and 7 graphitic shale samples (mostly from Swedish localities) was measured by the four point method. The method and the precautions needed in its application are briefly discussed. The results are presented in the form of a table which also gives other relevant data on the samples (e.g. percentage of ore in a given sample). The results are believed to be of interest to geophysicists engaged in prospecting for ore by electrical methods.

The following can be mentioned among the main conclusions. The electrical resistivity of ore samples varies “locally” on a single sample often by factors of 10–100 but usually within about ± 30% and it often varies by much greater amounts (factors of 100–10000) from one sample to another. The possible causes of such variation are mentioned. The resistivity of pyrite, haematite and magnetite ore samples does not show any significant correlation with the ore content for the samples investigated. There is furthermore no correlation between the standard deviation of the resistivity on a single sample on the one hand and sample resistivity or ore content on the other hand. In the case of chalcopyrite and pyrrhotite the observations suggested the following relations:

For chalcopyrite:

log10 (resistivity in ohmcm) = (6.2±4.2)/(vol. %CuFeS2) – (I‐39 ± o.38)

For pyrrhotite:

log10 (resistivity in ohmcm) = (73 ± 19) / (vol. %FeS) – (3.26 ± o.31)

The paper concludes by giving the approximate limits within which the electrical resistivity of the various ores investigated appreas to lie. The feasibility of detecting these ores by electrical operations is briefly discussed.
ON THE RELIABILITY OF HARMONIC ANALYSIS OF SEISMOGRAMS
Authors: KORSCHUNOW A.
Published: April 2006

Since harmonic analysis of seismograms seems to become more familiar in the interpretation of seismic data, the author presents the results of a thorough check analysis. Following a fixed scheme, one seismogram is analysed by means of a mechanical analyser (system Mader‐Ott). Standard deviation of Fourier coefficients is examined, and scattering in phase values is discussed. At the best, in the range of maximum amplitudes of the spectrum, the method yields 6% in phase scattering. At the worst, on either side of the spectrum, 13 % are obtained. Generally 8 % have to be taken in account. (Percentages in periods of partial‐waves of the analysis). The results are in accordance with former routine analysis (Korschunow, 1955).
THE TECHNICAL‐ECONOMIC ASPECTS OF AUTOMATIC DATA REDUCTION*
Authors: OLSON ROBERT W.
Published: April 2006

Abstract

The background of automatic data processing as well as other improvements in prospecting methods is almost certainly economic. Consciously and intentionally or intuitively and even subconsciously, economic forces are the drive for improvements.

Automatic processing can contribute to the increasing utility of seismic data. Reduction in the amount of routine work will permit talented people to utilize their time creatively on the more difficult problems. At the same time automatic reduction will provide for a greater volume of work. These two aspects will probably provide the first effective pressure for a high degree of automation.

It is to be expected, however, that the ultimate and greatest value will be better interpretation; possibly more detail, possibly clearer more definitive interpretation, possibly both.

Time concepts in the processing of seismic data are, of course, vital; either in simple time corrections of either static or dynamic nature or in treatment of signals in the time domain.

Much development work is needed before these advantages can be realized. Principal development needed is an increase in dynamic range in the overall system.
THEORETISCHE FRAGEN ÜBER BÜNDELUNG VON GEOPHONEN BEI UNTERTAGE‐MESSUNGEN*)
Authors: CELMI?Š AIVARS
Published: April 2006

Abstract

The arrays of multiple geophones used in underground seismic prospecting must satisfy two conditions:

1) In each group only a few geophones can be used.

2) The array must work in a rather wide frequency band.

In the present paper the effect of the 3 parameters (geophone spacing, sensitivity and time shift) of a linear array is investigated in order to improve the directional sensitivity of the array.

Necessary conditions which are independent of the frequencies are found for the optimum sensitivities of the geophones in a linear array.

The optimum values of the parameters mentioned above are calculated for arrays of 2 and 3 geophones and for a frequency band width which may be used in underground seismic prospecting.
REPRESENTATION OF DEPTH‐CONTOUR MAPS OF ARBITRARILY CURVED REFLECTION HORIZONS, INCLUDING REFRACTION OF RAYS, THREE‐DIMENSIONAL CASE*
Authors: GRAESER E. , LODE W. , POTT G.
Published: April 2006

A method of constructing depth contour maps of arbitrarily curved horizons obtained from seismic reflection surveys is discussed. This method takes into account three dimensional refraction, avoiding the construction of seismic cross sections of any kind. It requires little work even if refraction at several horizons is taken into account. The multiple layer problem is traced back to the single layer case. Discontinuities in velocity are also taken into account.
TECHNIQUE NOUVELLE DE MODÈLES RÉDUITS POUR LA PROSPECTION ÉLECTRIQUE
Authors: CAGNIARD L. , NEALE R. N.
Published: April 2006

Abstract

The use of small scale models in the interpretation of results of electric prospecting involves two majors difficulties: (1) the dimensions of the models and of the tanks in which the experiment is performed must be of unwieldy large sizes if one wants to be quite free from side effects; (2) the precise geometrical relation, in respect to the model, of the successive points where the interesting data are measured, requires an intricate installation, and is costly in both time and money.

The technique which is described in this paper eliminates these difficulties as well as some others. The surface of the ground is represented by the lower face of a thick horizontal plate of plexiglas which is laid at the surface of the liquid filling the tank. This plate is pierced by a great number of small holes whose coordinates have been measured initially with the necessary precision. The electrodes are then introduced into these holes without creating any perturbation in the distribution of the lines of current flow. A solution of copper sulphate is used as the liquid in conjunction with copper electrodes. In this way, a D.C. excitation is possible, combining precision with convenience.
SOME PROBLEMS OF THE AEROMAGNETIC SURVEYS1)
Authors: DOMZALSKI W.
Published: April 2006

A brief description of the procedure usually adopted for ascertaining the accuracy o aeromagnetic data is given as a background to the discussion of factors which affect this accuracy. These factors fall mainly into two groups: spatial positioning, i.e. relation to the ground surface, and effects contributing to the observed relative magnetic values. The evaluation of the observed anomalies in terms of the most probable causes and the anomalies themselves are directly influenced by the amount of the available control of factors mentioned above. The effects of various factors, such as plan positioning, height keeping, diurnal drift, are discussed, the arguments being based on theoretical and practical premises.
ÉTUDE DE DÖMES DE SEL AU GABON *)
Authors: REYRE D. , VALLET J. M.
Published: April 2006

The present development of exploration in Gabon and the latest successes obtained by drilling have led the authors to publish a historical account of the geological and geophysical research concerning two particularly typical salt domes: those of N'Daminzé and Ozouri.

Both of them are located in the western basin of Gabon: the first one in the zone of the savannahs, the second being a part of a series of salt domes in the delta of Ogooué.

The western basin of Gabon forms, as a whole, a huge westward‐inclined monocline and is characterized by a general phenomenon of diapirism the type of which, in the delta of Ogooué, greatly differs from that of the savannahs zone.

Because of the scarcity of outcrops in these zones geophysical exploration has been of valuable help.
RESULTS OF SUBSURFACE INVESTIGATIONS USING SEISMIC DETECTORS AND DEEP BORE HOLES*
Authors: BREWER H. L. , HOLTZSCHERER J.
Published: April 2006

abstract

The wells Parentis 10 and 12 which are located on the eastern edge of the Parentis anticline were found to be considerably lower at the top of the reservoir series than had been expected.

Unfortunately the village of Parentis is located in this important zone and no more seismic results could be obtained which might help locate faults and give a better picture of the area. To help in our understanding of the area, we attempted to investigate the subsurface conditions surrounding the wells by shooting shaped charges or primacord in the well and recording the returning seismic energy along profiles located on the surface. Thus far, we have used this method in three wells: Parentis 10, Parentis 12 and Lugos 2.

With the data given by a velocity survey in each well, time‐distance curves have been calculated for several typical possibilities: horizontal layers, dipping layers and the effect of a fault. A comparison of the calculated and experimental curves shows anomalies which correspond to a change of the average velocity along the travel path, which can correspond to geological changes such as: a sudden change of dip, a fault or a thickening of the section.

The anomalies have been studied on the different profiles from each well and a possible interpretation of the subsurface conditions has been given. The directions of the major accidents determined by this method are in general agreement with those found by the regular seismic shooting.
ĽENREGISTREMENT ÉLECTRONIQUE SIMULTANÉ DE PLUSIEURS COURBES DANS LES OPÉRATIONSDECAROTTAGE*
Authors: MURATORI G. , MANARA G. , CHIZZONI G.
Published: April 2006

Abstract

Electronic recorders have been used for recording borehole logs since several years.

Some difficulties are however experienced in recording more than two curves at the same time.

An experimental 4 curves electronic recorder has been constructed using up to date miniaturized servomechanism components.

A general description together with performance data is given; applications of the same construction principles to pen recorders with a greater number of curves and to photographic recorders are also discussed.
IMPÉDANCES ET MATRICES CARACTÉRISTIQUES EN PROSPECTION ÉLECTROMAGNÉTIQUE*
Authors: LOEB J.
Published: April 2006

Abstract

An analogy is established between the propagation of an electromagnetic field in a horizontally stratified conductive medium and that of currents in a linear electric network. This analogy will allow us to know in which case measurements executed at the surface of the ground can provide information about the properties of deeper layers. The situation is the same as when one tries, by means of impedance measurements at the input terminals, to know the properties of electric lines or lumped networks.

A symmetrical linear network establishes between:

Voltages V1 and V2 (respectively at input and output terminals)

Currents I1 and I2 (respectively at input and output terminals), the relationship

image

is called the “phase constant” and Z the characteristic impedance The table

image

is called “characteristic matrix”

If one then takes the horizontal components of an electromagnetic field, one can compare the voltage V with the horizontal electric field E (in volts m‐1) and the current I with the horizontal magnetic field H (in Amp m−1)

For plane waves in vacuum, one gets (Schelkunoff)

Z=C (velocity of light)

A layer whose thickness is D has a phase constant

⌈= 2 πD/λ (λ= wavelength)

For plane waves in a conductive, non magnetic medium whose conductivity is δ, one gets

image

For the system of waves created by a point‐source one expresses the solution, since it is classical, as a sum or integral of different modes. For each of these modes, one can still write a bilinear relationship similar to (1), and calculate Z and ⌈.

A generalization of this result is given.

Boundary conditions that exist at the surfaces of separation are met by writing the continuity of E and H. This condition exactly corresponds to the fact that there one V and one I at the junctions of various sections of lines, or networks.

The characteristic matrix of a cascade of networks‐or here that of a horizontally stratified ground– is the product of the matrixes of each network. If, in addition, one knows the end impedance–here the conductivity λn of the last layer, supposed to be infinite–one can compute the input impedance Re of the whole system. In electromagnetic prospecting, it is Re that conditions the observable field.

Inversely, if measurements were infinitely accurate, the. knowledge of the surface field would give all the thicknesses D and conductivities δ of intermediate layers, in the same way that impedance measurements at the input terminals of a cable would allow to locate any failure. The imperfection of measurements causes the elements located too far away (from the point of view of wave attenuation) to escape detection.
DIFFERENTIAL ELECTRIC LOG*
Authors: COLOMBO U. , SALIMBENI G. , SIRONI G. , VENEZIANI I.
Published: April 2006

A new logging method, which makes use of specific chemical reactions to locate petroleum or other minerals has been developed. The method has been named “Differential Electric Log” (CED).

In this paper the application to the CED method of redox (reduction/oxidation) reactions is discussed. A series of organic oxidants was found, capable of undergoing reaction with crude oil, sulphur, mineral sulphides, lignite. A small amount of an oxidant of this type is added to the drilling fluid and pumped into the borehole where reaction takes place in correspondence with layers containing oxidizable minerals. Two SP logs, recorded before and after the oxidation, are compared and the presence of such minerals is thus detected.

A theoretical hypothesis explaining the mechanism of the potential change due to the chemical reaction is proposed both in the case of electronically conducting and non conducting minerals. The influence of redox potential on SP is discussed.

The results of laboratory experiments on several different oxidizable ores and those of field tests performed on pyrite, lignite, and oil wells are reported on and discussed on the basis of the theoretical hypothesis proposed.
VARIATION OF THE WORDEN GRAVIMETER SMALL DIAL SCALE FACTOR WITH TIME*
Authors: SAXOV S.
Published: April 2006

Abstract

A series of repeat observations during a period of 5 years reveal a variation with time of the Worden gravimeter No. 142 small dial spring system. A possible change in the gravity difference concerned is ruled out. It is shown that the small dial scale factor has diminished by about 0.25 % within the last two years against about 0.5 % four to five years ago. The ratio of L.D. to S.D. has been analysed and the results obtained show confirmation of the change in the small dial system and prove a consistency in the large dial system.
PROBLEMS AND RESULTS WITH REFRACTION SEISMICS IN BOREHOLES
Authors: HOLSTE W.
Published: April 2006

Abstract

Recently, quite good determinations of interfaces have been made by means of seismic well surveys. These were carried out for various oil companies in Northwest Germany, especially on salt‐domes, and in Southern Germany, and in the area of the Upper Rhine Valley. It was the purpose to determine the configuration and position of salt‐flanks and important planes of stratification in the neighbourhood of deep wells, and thus to reduce the risk of expensive wells.

For the delineation of the boundary surfaces the method described by Gardner in “Geophysics 1949” was applied.

The problems arising and the results obtained are discussed in connection with some interesting examples. From them we see, above all, that a knowledge as precise as possible of the seismic velocities of all media involved in the measurement is very important. A good idea of the general stratification in the area of deep wells seismically surveyed will make possible a rational and adequate planning of the survey program and will facilitate the interpretation.
RESULTS OF SURFACE REFLECTION SEISMIC MEASUREMENTS IN THE SIDERITE DISTRICT OF THE SIEGERLAND*
Authors: REICHENBACH R. , SCHMIDT G.
Published: April 2006

Abstract

The iron ores of the Siegerland‐district are found in lodes occurring in schists of Lower Devonian age. In the course of the geophysical exploration for these ores, an attempt was also made to clarify the structure and the tectonics of the substratum of the sedimentary rock formations by seismic reflection measurements from the surface. Reflections were recorded in great numbers from layers of Silurian and Devonian age. The form of the folding of the strata derived therefrom corresponds well with that deduced from geological investigations. Beyond that, correlatable reflections were recorded from horizons down to a depth of nearly 25 000 m. It turned out that the iron ore lodes known from the mine workings occur almost vertically above those places where greater dislocations appear in the deepest substratum, and which geologically could be interpreted as fracture zones. The results so far obtained seem to be indicative of the fact that the tectonics of the deepest substratum and the occurrence of ore deposits are related to each other.
INTRODUCTION TO THE INTERPRETATION OF RESISTIVITY MEASUREMENTS FOR COMPLICATED STRUCTURAL CONDITIONS*
Authors: ALFANO L.
Published: April 2006

Abstract

A study is made of the possibility of calculating electric potentials, and therefore of interpreting apparent resistivity measurements, when the ground presents structural conditions more complicated than plane, parallel stratification.

For this work a schematic type of structure has been chosen, in which the discontinuity planes for electric resistivity are both parallel and perpendicular to the level of the ground.

The problem has been examinated in its general aspect, and then some criteria for the numerical calculation have been indicated.

Some calculated examples are presented, relevant to vertical electric soundings accomplished by conventional technique, for particular types of structure.
SOME OBSERVATIONS OF GAMMA RADIATION EMITTED BY A MINERAL SPRING IN JAMAICA
Authors: VINCENZ S. A.
Published: April 2006

Abstract

The decay rate of gamma radiation emitted by a Jamaican mineral spring was measured using portable rate meters. The results of these experiments, supported by auxiliary tests, suggested that the main radioelement causing the radioactivity was radon 222. Fluctuations in the intensity of the radiation were studied in situ. An inverse relation between the intensity and the discharge rate of water was established and the effect of rainfall and of earthquakes was investigated. Some suggestions are made concerning the possible source of radon.
A NEW DEVICE FOR SEISMIC SURVEY EQUIPMENT *
Authors: MERLINI E.
Published: April 2006

Abstract

In the laboratories of the agip mineraria a new apparatus has been developed which, utilizing reflected energy collected by several groups of seismometers, provides on a single trace an indication of the total energy level. This indication is controled in time according to an exponential characteristic, thus compensating for the attenuation which is effected in the subsurface. The apparatus enables indications of successive energy levels to be obtained for different shots, thus furnishing a time section even during the routine field work.
ON THE IDENTIFICATION AND CONSTRUCTION OF REFLECTED REFRACTIONS *
Authors: BORTFELD R. , HÜRTGEN H.
Published: April 2006

Abstract

Reflected refractions are considered as the limiting case for ordinary steeply dipping reflections. Particularly, reflected refractions may be constructed (migrated) according to the same principles as ordinary reflections. In view of the inherent inaccuracy of the velocity data, there is no discrimination between reflected refractions and other steep events by methods of construction. Velocity determinations from reflection data also show a continuous transition from steep reflections to reflected refractions. I.e., it is impossible to discriminate by seismic ray methods between reflected refractions and other steep events.

If disturbing, steep events may be attenuated to a great extent by special shot and geophone set‐ups. Also in this connection it is unnecessary to distinguish between reflected refractions proper and steep reflections.

It seems to be more rational to consider steep events as ordinary steep reflections in the beginning of a survey, because otherwise real structural indications might possibly be thrown away.
MEASUREMENTS OF AMPLITUDES OF REFLECTED SEISMIC WAVES*
Authors: KOEFOED O.
Published: April 2006

Abstract

Measurements have been made of amplitudes of reflected seismic waves, in order to investigate their change as a function of the shotpoint‐seismometer distance and of the position of the reflection point. The change with shotpoint‐seismometer distance, after correction for geometrical divergence, was usually small. This indicates either a rather strong difference between the values of Poisson's ratio for adjacent strata, or, more likely, a rather small value of the absorption coefficient. In one instance a very strong increase in amplitude with shotpoint‐seismometer distance was observed. This may be attributed to incidence near the critical angle. In another instance a pronounced increase in amplitude with the position of the reflection point was observed over a very short distance. This may be due to an elongated depression of the reflecting boundary.
WELL SURVEYS AND THE CALIBRATION OF VELOCITY LOGS*
Authors: SCHWAETZER T.
Published: April 2006

Abstract

In the last two years several double‐receiver Velocity Logs (V‐Logs) have come into service. Theoretically, in this type of log the effect of the travel time in the mud and in the invaded or altered formations, responsible for the “Lag” (or delay times) in single receiver V‐Logs, could be eliminated. Thus the integration of the interval times would give the “real” vertical time as a function of depth. In practice, several authors have already noted that even for V‐logs with two receivers the integrated times differ from the results of the conventional well surveys.

We consider here some of the geometrical, geological and instrumental factors that affect the time measurement of double receiver Velocity Logs, as well as the possibility that the discrepancy between the V‐logs and the conventional well survey could in some cases be due to faults, dip, folding, or the intrusion of high velocity layers near the well. Some examples are given, and the question of the polarity of first arrivals in well surveys is discussed.

At present the discrepancies between the integrated times of even double receiver V‐Logs and the results of the well surveys remain too great to permit us the economy of eliminating the well survey. Furthermore, for the study of these discrepancies we must continue to shoot a considerable number of calibration points. We have, however, succeeded in reducing greatly the cost of the conventional survey by reorganising our well shooting methods. These methods, as well as the problems of surface corrections and the choice of datum plane they entail, are discussed.
COMPARATIVE CONSIDERATIONS ON THE ENERGY CONTENT OF SEISMIC WAVES IN CENTRAL AND LINEAR PATTERN SHOOTING*
Authors: PIERAU H. , ROSENBACH O.
Published: April 2006

Abstract

In continuation of a publication by Pierau and Mueller (1960), theoretical and experimental comparisons are made about the energy content of seismic waves for central and linear shotpoint arrangements. The following results are obtained:

Using shotpoint arrangements as chosen for the investigation, the energy content of deep reflections is greater in linear than in central pattern shooting, provided that the total quantity of charge is the same in both cases. Furthermore the seismograms obtained with linear shotpoint arrays are less disturbed by surface waves than those obtained in central pattern shooting. Both effects are superimposed and improve considerably the signal‐to‐noise ratio, thus explaining the improvement in the quality of deep reflections by uniformly linear shotpoint arrangements.

In Fortführung einer Publikation von Pierau und Müller (1960) werden theoretische und experimentelle Vergleiche über den Energiegehalt seismischer Wellen bei Zentralund Reihenschüssen durchgeführt, die folgendes Ergebnís liefern:

Bei den gewählten Anordnungen der Schussbohrungen und unter der Voraussetzung gleicher Gesamtladungen sind die tiefen Reflexionen beim Reihenschuss energiereicher als beim Zentralschuss. Ausserdem sind die Seismogramme von Reihenschüssen weniger durch Oberflächenwellen gestöit als diejenigen von Zentralschüssen. Beide Effekte zusammen verbessern wesentlich das Verhältnis von Nutz‐ zu Stör‐Energie und erklären die Verbesserung der Qualität tiefer Reflexionen durch gleichmässig lineare Anordnung der Schussbohrungen.
ON THE SOLUTION OF ONE DIMENSIONAL ELASTIC WAVE PROPAGATION PROBLEMS IN STRATIFIED MEDIA BY THE METHOD OF CHARACTERISTICS
Authors: BLACK M. C. , CARPENTER E. W. , SPENCER A. J. M.
Published: April 2006

Abstract

This paper describes a numerical method of solution for wave propagation in a medium whose elastic parameters and density vary with depth in any specified way. Results for a simple two layer problem are given to illustrate the method, and the extension to problems of current geophysical interest is briefly discussed.
SISMOGRAMMES SYNTHETIQUES; POSSIBILITES, TECHNIQUES DE REALISATION ET LIMITATIONS*.
Authors: BOIS P. , CHAUVEAU J. , GRAU G. , LAVERGNE M.
Published: April 2006

Abstract

1°– Synthetic seismograms have been computed with and without multiples by exact and by approximate methods. By means of these seismograms, some studies have been made on the various multiple reflections, the character of the films, the effect of the surface in the formation of multiples, as well as on the shape of the pulse and the spectra of seismograms. Refraction synthetic seismograms have also been realized on schematic examples with fault and pinch‐out.

2°– Various techniques for synthesizing seismograms are described which make use of analogue computing equipment such as a bar with variable diameter, or of digital computers. The orders of magnitude of the prices of these various methods are shown.

3°– Some of the limitations are described which are imposed on synthetic seismograms by the hypotheses and the inaccuracies of our knowledge of the conditions which prevail underground.
Ľ ANALYSE DES FILMS REELS ET LEUR COMPARAISON AVEC LES FILMS SYNTETIQUES
Authors: DELAPLANCHE J. , LEDOUX Y.
Published: April 2006

Abstract

The practical use of synthetic records involves previous studies on field records from an original point of view; these studies consist essentially in analysing and cancelling noise, in bringing out the form of pulses and the character of seismic events, in detecting multiple arrivals. Various tools have been tested for this purpose: high multiplicity shooting, analysis of conventional well velocity surveys, mixing or selecting traces, varied filters; all these operations are facilitated by the use of magnetic recording.

After several examples of these methods are given, it is shown how the results of such studies can help to make and discuss synthetic records with and without multiples. The share of multiple events and their effect on the efficiency of the later comparisons are especially treated.

The authors finally present some specific examples of successful comparisons between synthetic records and field records treated beforehand. They insist on the discrepancies and on the importance of finding their origin, for the most tangible results in seismic interpretation generally appear during the analysis of such discrepancies.
EXPERIMENTS WITH STATIC‐RESISTANT BLASTING CAPS*
Authors: BANVILLE J. H. , RICHARD H.
Published: April 2006

Abstract

Premature detonation of seismic blasting‐caps may be caused by the accumulation of an electrostatic charge. This is especially true in desert areas where there are many sandstorms.

Two makes of static resistant cap have been tested in the laboratory and the results compared with those for non‐resistant caps made by the same manufacturers. The full results are given in the table, the breakdown voltage for the resistant caps is in the range 20–30,000 volts as compared with the range 10–15,000 volts for the ordinary cap.

It is strongly recommended the static resistant caps should always be used and that experiments on premature detonation from this cause should bemade in the field.

In January 1960, 20 crews in the Sahara used a total of 146,150 static‐resistant blasting caps.
DEVELOPMENT OF NEW TECHNIQUES APPLIED TO THE SEARCH FOR STRATIGRAPHIC TRAPS*
Authors: CARISSIMO L. , D'AGOSTINO O.
Published: April 2006

Abstract

The “Summarizer” is a new device designed and manufactured by the Agip Mineraria Electronic Laboratories which gives an output which is a function of the total energy detected by the geophone spread. This paper gives some examples of its use in stratigraphic mapping.

Test surveys have been carried out in an area of the Po basin where the formations show many facies variations. Three gas fields of known geological features were considered. The usefulness of various methods of representation was evaluated as well as the contribution given by the new device. It was noticed that the results given by the “Summarizer”, when added to those obtained by standard and “variable area” sections, supply the interpreter with new useful elements. Lateral facies variations between gravels and shales have been recognized and localized.
PROBLEMES POSES A LA SISMIQUE DANS LA REGION PARISIENNE*
Authors: MILLOUET J.
Published: April 2006

Abstract

Seismic work near Paris first began in 1954. Two major difficulties characteristic of this region rapidly appeared:

The existence of silicified limestone beds in the plateaus: these high‐velocity beds, hard to drill, make it difficult to obtain surface corrections and carry strong “ground‐roll” noise waves.

The feeble structural variations call for a very accurate control of time measurements.

Drilling difficulties, and the need to eliminate parasite waves, have led to the adoption of pattern shooting from hammer‐drilled holes.

The most effective elimination of ground roll has been obtained by shooting with a lateral offset of 600 m. This method has made it possible to work in regions where originally no reflections could be obtained.

The difficulty of obtaining surface corrections has induced us to shoot up‐hole velocity surveys in deep holes at particularly important points. This work is done by a special crew. At other shot points, surface corrections are calculated from structural maps of surface strata and from velocity‐depth curves. The accuracy of these corrections, checked by drilling and velocity surveys, appears sufficient.

The determination of lateral velocity variations by surface velocity shooting (X2/T2) is not feasible in this part of the Paris basin, as the accuracy of this method is insufficient.

The control of reflection times must take into account the deformation of the signal as a function of the type of recording equipment and filters used, and also the modifications of the character of the reflection due to lateral stratigraphic variations. These variations can be observed by comparing the different velocity logs.
PROPAGATION OF WAVES IN INHOMOGENEOUS MEDIA
Authors: SCHOLTE J. G. J.
Published: April 2006

Abstract

A method is developed for determining the propagation of a wave of arbitrary shape in an inhomogeneous medium in which both the density and the velocity change with depth according to an arbitrary continuous function. The solution is obtained by means of successive approximations. The successive terms in this approximation correspond to the direct wave, single reflections and multiple reflections of successive order. The general formulae are then applied to three particular types of transition layer.
DEEP ORE EXPLORATION BY ELECTRICAL METHODS
Authors: BRAEKKEN H.
Published: April 2006

Abstract

It has been found that ore prospecting by suitable electromagnetic and electrical methods may under favourable conditions—such as occur in parts of Norway—be carried out to greater depths than have so far been realized. By 500 c.p.s. electromagnetic measurements at the surface there was located a deep ore body, occurring in the continuation of, but separate from, an old ore body, which had been worked down to its end at a depth of some 500 m. The new ore body, starting at a depth of some 700 m and continuing downward with a slightly more dipping axis, has been traced over a considerable distance by further electromagnetic measurements at the surface, with the energizing current led directly to the ore in drill holes. Possibilities, problems and further improvements in deep E.M. techniques of measurement and interpretation are discussed. By D.C. equipotential mapping at the surface, with the current led directly to the ore, the location and direction of the deep ore body was established in agreement with the electromagnetic findings. Problems and developments in deep Charged Potential prospecting and interpretation are discussed. By 500 c.p.s. electromagnetic and D.C. potential measurements in drill holes essential information has been achieved both in locating ore formations beside a drill hole and in deciding whether ore formations in different drill holes are connected or not.
ATTENUATION DES ONDES SISMIQUES DANS LES SOLIDES*
Authors: LOEB J.
Published: April 2006

Abstract

For the propagation of acoustic waves in formations, laboratory experiments yield an expression of the form:

image

in which

A is the amplitude (strain or stress)

A
0 some constant coefficient

x the coordinate according to which propagation takes place

α the attenuation coefficient

C velocity

ω the angular frequency of sinusoidal oscillation.

No analogy between this law and that of electromagnetic waves can be made, since:

coefficient α is not independent of frequency: its expression is α=Kω (K constant);

however, with present recording technique, no noticeable dispersion can be found.

The present paper shows how results are compatible if losses of energy are accounted for by a hysteresis phenomenon that is analyzed (see Figure). Stress T is in abscissae, and strain δu/δx, multiplied by a coefficient E′ characteristic of the elastic properties of the solid, is in ordinates. The horizontal part of the curve is θ. It is supposed that the absorption properties of the ground are given by some dimensionless coefficient

λ=θ/T−

Then one gets

α=ωλ/4C

If λ≪ 1, we get the propagation law

image

An attenuation takes place without phase shift, and consequently without dispersion.

The author reverts to the inapplicability of the superposition principle, and foresees theoretically, for instance, that a strain T′ cos ω′t, where T′ > T and ω′ > ω, can completely cancel coefficient α.