On the importance of gathered current in turam measurements

Lile, Ole Bernt; Pelkonen, Raimo; Singsaas, Per

doi:10.1016/0016-7142(81)90037-5

Cited by 1 publication

(7 citation statements)

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“…The electromagnetic method using a long wire or a large loop on the ground surface as energizing device was developed in the 1920s. The advantage using either a large square loop or a single grounded wire is lower fall-off rate of the primary field The total magnetic field from a cable on the surface of a conducting half-space with a conductor [6].…”

Section: Long Wire Electromagnetic Measurements (Turam Em)mentioning

confidence: 99%

“…Due to the measurement technique using two coils, the method was called Turam, meaning two coils in old Swedish [2,3]. There are several publications describing both the theory and field results of this method [4][5][6]. The measurements were carried out in the frequency domain with a fixed frequency.…”

Section: Long Wire Electromagnetic Measurements (Turam Em)mentioning

confidence: 99%

“…The resulting field will not penetrate as deep into the ground as in free space and will be phase-shifted relative to the primary field. Figure 1 shows the resultant field calculated for a two-dimensional model of the half-space and a conductor [6].…”

Section: A Long Wire On the Surface Of A Conductive Half Spacementioning

confidence: 99%

“…The secondary magnetic field alone can be computed and displayed. Figure 2 shows the induced magnetic field from currents in a conducting half-space without conductor [6]. The induced currents in the ground create a circular pattern of the magnetic field with the vortex below the cable.…”

Section: A Long Wire On the Surface Of A Conductive Half Spacementioning

confidence: 99%

“…If it is possible to obtain galvanic contact with a conductor in the ground, one should use this as one of the grounding electrodes of the energizing cable. Lile et al [6] investigated how gathered currents could be modeled by a two-dimensional computer model. Figure 3 shows how the anomalous magnetic field lines in the ground are influenced by gathered current in a nearby conductor.…”

Section: Current Gatheringmentioning

confidence: 99%

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Long Wire Electromagnetic Measurements (Turam EM)

Lile¹

2021

Geophysics and Ocean Waves Studies

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In Scandinavia, EM measurements have traditionally been popular in sulfide ore exploration. The EM methods using a stationary cable loop or a long wire on the ground surface were called Turam. The wire was grounded by electrodes at the ends. The name, Turam meaning two coils, got the name after the measurement system using two coils measuring the quotient and the phase difference of the vertical field. The measurements were performed in the frequency domain, with frequencies around 400 Hz. Using a large cable loop or a long wire grounded at both ends has advantages as energizing transmitter, which should be utilized in deep exploration. The fall-off rate for the primary field is small, and the electric field can be directed in line with strike direction or the direction of the axis of the mineralization. Examples of the interaction between the energizing cable and the conducting half-space are illustrated by computed models. The grounding points can be shifted with repeated measurements for each grounding position. Both man-made and geological noise can be reduced in this way. Field examples are given in the chapter.

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Section: Long Wire Electromagnetic Measurements (Turam Em)mentioning

confidence: 99%

Section: Long Wire Electromagnetic Measurements (Turam Em)mentioning

confidence: 99%

Section: A Long Wire On the Surface Of A Conductive Half Spacementioning

confidence: 99%

Section: A Long Wire On the Surface Of A Conductive Half Spacementioning

confidence: 99%

Section: Current Gatheringmentioning

confidence: 99%

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