摘要:

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.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02091.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTSome of the theoretical bases of the bubbling method (different terms of an equipotential family can be approximately obtained using this method) are considered. A few examples for application of this method are given (a programme for a digital computer is used), showing its efficacy at solving problems from the exploration geophysics.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02092.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

RÉSUMÉLa polarisation provoquée (P.P.) est un phénomène particulièrement complexe non seulement du point de vue des mécanismes physiques qu'elle met en jeu, mais aussi du point de vue mathématique. A cause de ľanalogie que présentent les techniques expérimentales de sondage électrique classique de résistivité?une: part, et de sondage P.P. ?autre part, on éprouve une certaine tendance à interpréter les données du second à la manière du premier. C'est pourquoi il nous a semblé utile de calculer un modèle mathématique idéalisé et schématisé qui permette tout au moins de se rendre compte de ľallure générale du phénomène auquel on peut s'attendre. On s'est placé dans le cas le plus simple, celui ?une couche mince polarisable qui présenterait la même conductibilitéélectrique que le milieu dans lequel elle est intercalée. On se propose de fournir le résultat de ce calcul pour le cas simple ?une seule électrode ?injection et ?une seule électrode de mesure et, à partir de ces données, de calculer ľallure ?un sondage P.P. de type classique avec quadripôle Wenner.On compare ensuite le diagramme calculé avec une courbe expérimentale obtenue sur un modèle figurant une couche mince de minerai disséminé II s'avère, en fin de compte, que ľallure générale du phénoméne fournit une base d

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02093.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

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 resistivit

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02094.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTA method to analyse aeromagnetic profiles is proposed: several horizontal (width‐) and vertical (amplitude‐) parameters are deduced from the anomalies. These parameters are then compared with diagrams drawn on a logarithmic scale. The comparison yields depth and magnetization of the causative bodies.The method lends itself equally well to a quick estimate and to a thorough interpretation, depending on the number of parameters deduced and on the number of diagrams. It can be applied also to the anomalies of the total field and its vertical gradi

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02095.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

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. SiHvertical/Hhorizontal est inférieur à 10%, on peut pratiquement supppser ľ uniformité et appliquer les formules classiques de restitution des résistivités vraies. SiHvertical/Hhorizontal 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

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02096.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

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) bexand let the vertical plane through it be thex‐zplane and let thez‐axis be a line in this plane perpendicular to thez‐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 cosinesa, b, cof the transmitter coil axis T, (2) the direction cosinesd, e, fof the line L joining the transmitter and the receiver coils and (3) the direction cosinesg, h, iof the receiver coil axis R. Hence a set of indices conveniently written as Ta, b, cLd, e, fRg, h, idescribes 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

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02097.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTContinuous velocity log data from the Upper Cretaceous section of about 65 wells from NW. Germany have been studied in order to find some factors which affect the behaviour of elastic wave velocities in carbonate rocks. It could be assumed for these particular rocks that the velocities they exhibit may be subject predominantly to their state of compaction and their lithology (shale‐carbonate ratio).Considering the behaviour of the VL‐curve, several types could be distinguished: The basic type r for which the shale‐carbonate ratio remains almost invariable over a large depth range (as suggested i.a. by a constant degree of radiation in the accompanying Gamma Ray log) discloses a clear relationship between interval velocity (measured as travel time per meter) and overburden pressure.Velocity profiles of log type r and also “peak” velocities from “pure” limestones, plotted versus depth indicate an increase rate almost identical to that of Jurassic shales.It is shown that the lithologic constantcan be extracted from the Velocity Log data and then used for mapping fades changes in an area with sufficient well control.In certain cases it is even possible to determine the rate of uplifting (or the original maximum burial position) for a carbonate rock which has an anomalous high velocity in respect to its

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02098.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTThe principle of optical pumping allows the design of magnetometers with high sensitivity. When mapping the field of the total magnetic force, it is no longer possible to make full use of the accuracy of the instruments because the accuracy of the reduction of the diurnal variation is limited. By simultaneously recording with two instruments in different altitudes, the vertical gradient can be measured which doe's not depend on the time variation of the magnetic field. Therefore, the gradiometer seems to be a more adequate tool for oil exploration than the magnetometer.It is investigated in this article whether the results of this gradiometer or the measurements of the total magnetic field by the high sensitive magnetometer are more useful in oil exploration. The article comes to the conclusion that for most problems of oil exploration the total magnetic field is a more valuable unit than the vertical gradient measured directly by the gradiometer. The total magnetic field allows a better investigation of the tectonics than the vertical gradient. The apparent advantages of the gradiometer claimed by its supporters are mainly based on inconsistent mathematical concepts.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02099.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRaCTIn seismic studies being carried out to elucidate the structure at depth of the Midland Valley rift and the Tertiary igneous province in the West of Scotland, a lack of deep boreholes makes the collection of velocity data imperative for identification of seismic events and for determinations of depth. Three methods are used to investigate the correlation of seismic velocities and geological formations. The results show as strong a dependence of velocity on method of measurement as on lithology and the wide spread of values within a given formation makes the attribution of discrete velocity ranges to specific formations impossible. Changes of velocity are more significant than absolute values. The variations in both are discussed.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1970.tb02100.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY