Depth of detection of buried resistive targets with some electrode arrays in electrical prospecting

Abstract

Assuming the minimum detectable anomaly to be 10%, depths of detection of a 2D vertical resistive sheet of thickness t are found to be 4.0t, 3.0t, 4.0t and 4.0t with Wenner, two‐electrode, three‐electrode and dipole‐dipole (β‐Wenner) arrays, respectively, when the array spread is in‐line. On the other hand, the depths of detection obtained with a broadside spread of the arrays right over the sheet are much less and are correspondingly 2.5t, 2.0t, 2.5t and 2.5t. An increase in the depth extent W of the sheet from 10t to 20t does not increase its depth of detection with the arrays. The depths of detection of an infinitely resistive horizontal cylinder of radius R are respectively 1.5R, 1.8R, 2.0R and 2.0R with the above‐listed arrays when the array spread is in‐line. With broadside spread of any of the arrays, the depth of detection is seen to be 2.5R. In the case of a spherical target of radius R, the detection depths of any of the arrays are found to be small and to vary between 0.8R and 1.1R. Comparatively, the detection depths of resistive targets are much lower than those of conductive targets of the same size and shape, with any electrode array. Among all the arrays studied, the two‐electrode array performs worst in the detection of resistive targets while it performs best in detecting conducting targets of limited lateral extent. In the case of a spherical target, either resistive or conductive, there is no distinct change in its detection depth with array.

Estimation du champ de transmissivité d’un aquifère alluvial fortement hétérogène à partir de la résistance transversale. Application à la nappe du Haouz de Marrakech (Maroc)

“…La détermination du volume de terrain investigué par les sondages électriques fait l'objet de controverse dans la littérature (EVJEN, 1938;ROY et APPARAO, 1971;KOEFOED, 1972;APPARAO et GANGADHARA, 1974;BHATTACHARYA et SEN, 1981;APPARAO et al, 1997). En revanche, en hydrogéologie, le volume d'aquifère influencé par un pompage d'essai en régime transitoire est représenté par un cylindre de rayon r égal au rayon d'influence de l'essai, et de hauteur égale à la tranche saturée.…”

Physical Modeling Results on Modified Pseudodepth Sections in Exploration of Highly Resistive Targets

“…Because of these reasons, the array is not suggested for surface prospection of resistive targets. For details, please see APPARAO et al (1997).…”

Studi Pemodelan Respon Polarisasi Terinduksi dalam Kawasan Waktu (TDIP) terhadap Kandungan Mineral Logam, Sebuah Hasil Awal

“…Medium latar (host medium) digunakan air tanah yang mendekati sifat medium homogen isotrop [7] . Target digunakan bola pejal dengan diameter 10 cm dari bahan campuran pasir, besi dan semen dengan perbandingan tertentu [8], [9] . Kadar besi bervariasi dari 0% sampai 80%.…”