Outlining of Salt Masses by Refraction Methods

Musgrave, A. W.; Woolley, W. C.; Gray, H.

doi:10.1190/1.1438681

Cited by 12 publications

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“…Early papers, Gardner (1949) and Musgrave et al (1960), discuss salt proximity surveying and aplanatic analysis. The basic concepts discussed by these authors are incorporated in a Marathon developed computer program which permits entry Case History 5/Modeling for Salt Proximity Surveys 155 of a complex velocity model and generates aplanatic curves for a complete suite of recordings.…”

Section: Salt Proximity Surveys and Aplanatic Analysismentioning

confidence: 99%

Seismic Modeling of Geologic Structures

Fagin¹

1991

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Section: Salt Proximity Surveys and Aplanatic Analysismentioning

confidence: 99%

Seismic Modeling of Geologic Structures

Fagin¹

1991

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“…However, occasionally and, where geologic conditions permit (that is, where there is sufficient velocity contrast between an ore body and its surrounding medium, and where both media are respectively homogeneous), refraction techniques have been used successfully, for the direct detection and delimitation of ore and other deposits (Gillin et al 1942;Musgrave et al 1960;Elliot 1967). Unfortunately, such ideal conditions are the exception rather than the rule for most ore-bearing structures.…”

Section: Introductionmentioning

confidence: 98%

The feasibility of delineating non-layered anomalous velocity zones by a combination of fan shooting and least-squares analysis

Waboso¹,

Mereu²

1978

Can. J. Earth Sci.

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Laboratory velocity measurements on nickel-sulphide samples show that the velocity contrast between a sulphide body and rocks typical of the Canadian Shield can be fairly large. In view of this, the feasibility of delineating the sulphide body by means of acombination of fan shootingand least-squares analysis was examined by both computer model simulation and field experimentation. The method consists, essentially, of shooting several fans emanatingfrom the perimeter of a rectangle around the suspected location of a deposit, and measuring the corresponding first arrival times. The rectangle is then divided into grid units, and the apparent velocity in each grid unit is found by least-squares solutions of an overdetermined system of linear equations.The computer model tests indicate that in cases where the velocity contrast between the surrounding medium and the anomalous zone is good, and each medium homogeneous, the method is a potentially useful auxiliary technique for mining exploration. However, field tests show that these requirements (i.e., good velocity contrast and homogeneity of each medium) may constitute a serious limitation of the method.Les mesures de vitesse en laboratoire sur des echantillons de sulfure de nickel montrent que le contraste de vitesse entre un massif de sulfures et les roches typiques du Bouclier canadien peut ttre relativement grand. Dans cette optique, on a examine la possibilite de delimiter le massif de sulfures par une combinaison de tir en eventail et d'une analyse par moindres carres en experimentant sur modele avec une simulation par ordinateur et sur le terrain. La methode consiste essentiellement a tirer plusieurs eventails emanant du perimetre d'un rectangle autour de la localisation presumee d'un dep6t et a mesurer les temps des premieres arrivees correspondantes. Le rectangle est ensuite subdivise en mailles unitaires et la vitesse dans chaque maille est calculee a I'aide de solutions par la methode des moindres carres d'un systeme surdetermine d'equations lineaires.Les essais sur modele par ordinateur indiquent que la ou le contraste de vitesse entre le milieu ambiant et la zone de I'anomalie est bon, et quand chaque milieu est homogene, la methode peut devenir une technique auxiliaire utile dans I'exploration minerale. Toutefois, les essais de terrain montrent que ces conditions (bon contraste de vitesse et milieux homogenes) peuvent constituer une limite serieuse a la methode.[Traduit par le journal]Can.

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“…or more, use has been made of existent wildcat wells for the purpose of making a seismic exploration [of salt dome structures]." By the 1940s, use of a single borehole seismograph to profile the flanks of a salt dome was an established practice (Gardner 1949;Musgrave et al 1960).…”

Section: Introductionmentioning

confidence: 99%

Borehole Seismic Networks and Arrays

Bohnhoff

Malin

2020

Encyclopedia of Solid Earth Geophysics

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Borehole strings and chains; Buried grids; Downhole networks and arrays; Vertical arrays; VSP DefinitionIn the broadest sense, borehole networks and arrays are assemblies of geophysical instruments placed in the subsurface via boreholes. This article focuses on their seismological applications. While common usage often blurs the distinction between a network and an array, this article explicitly distinguishes between their operational theories and engineering practices, and in the case histories and examples provided. To strictly qualify as an array, the assembly of instruments must include matching or similar sensors located at different depths in one well or lateral separated in different wells. The combined natural-frequency responses and spacing of the sensors must also include a range over which they can be used to improve signal detection and analysis via time series processing. Outside of this range a borehole assembly acts as a network of independent detectors. Early DevelopmentsThe general use of boreholes for making subsurface seismic measurements appears to have begun nearly 100 years ago. McCollum and LaRue (1931) report that "during the past year

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Outlining of Salt Masses by Refraction Methods

Cited by 12 publications

References 0 publications

Seismic Modeling of Geologic Structures

Seismic Modeling of Geologic Structures

The feasibility of delineating non-layered anomalous velocity zones by a combination of fan shooting and least-squares analysis

Borehole Seismic Networks and Arrays

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