Desktop computer processing of coincident and central loop time domain electromagnetic data

Raab, Paul; Frischknecht, F.C.

doi:10.3133/ofr83240

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…Directly over the basement depression the overburden layer thickens to 1 100m, while far away from the depression, the layer thins to 500 m. In plan view the basement depression extends 2 800 m in the x any y directions. Six central-loop stations, with loops 1 krn on a side, profile over the basement depression at x = 500, 1 000, 1 500, 2 000, 2 500, and 3 500 m. (33) is evalu ated using an algorithm described by Raab and Frischknecht (1983).…”

Section: Overburden Thickhessmentioning

confidence: 99%

Transient electromagnetic response of a three‐dimensional body in a layered earth

1986

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by a large rectangular loop is substantial when host currents are strong near the conductor. The more con ductive the host, the longer the galvanic responses will The three-dimensional (3-D) electromagnetic scatter persist. Large galvanic responses occur if a 3-D conduc ing problem is tirst formulated in the frequency domain tor is in contact with a conductive overburden. For a in terms of an electric field volume integral equation.thin vertical dike embedded within a conductive host, Three-dimensional responses are then Fourier trans the 3-D response is similar in form but differs in mag formed with sine and cosine digital filters or with the nitude and duration from the 2-D response generated decay spectrum. The digital filter technique is applied to by two infinite line sources positioned parallel to the a sparsely sampled frequency sounding, which is re strike direction of the 2-D structure.placed by a cubic spline interpolating function prior to We have used the 3-D solution to study the appli convolution with the digital filters. Typically, 20 to 40 cation of the central-loop method to structural interpre frequencies at five to eight points per decade are re tation. The results suggest variations of thickness of quired for an accurate solution. A calculated transient is conductive overburden and depth to sedimentary struc usually in error after it has decayed more than six ture beneath volcanics can be mapped with one orders in magnitude from early to late time. The decay dimensional inversion. Successful 1-D inversions of 3-D spectrum usually req uires ten frequencies for a satisfac transient soundings replace a 3-D conductor by a con tory solution. However, the solution using the decay ducting layer at a similar depth. However, other pos spectrum appears to be less accurate than the solution sibilities include reduced thickness and resistivity of the using the digital filters, particularly after early times.(-0 host containing the body. Many different l-D Checks on the 3-D solution include reciprocity and con models can be fit to a transient sounding over a 3-D vergence checks in the frequency domain, and a com structure. Near-surface, 3-D geologic noise will not per parison of Fourier-transformed responses with results manently contaminate a central-loop apparent resistivi from a direct time-domain integral equation solution. ty sounding. The noise is band-limited in time and even The galvanic response of a 3-D conductor energized tually vanishes at late times.

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Section: Overburden Thickhessmentioning

confidence: 99%

Transient electromagnetic response of a three‐dimensional body in a layered earth

1986

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“…The time domain apparent resistivity can be obtained from the analytical expression for the induced electromotive force. The expression for the induced electromotive force of the central loop device deduced by the American scholars Raab and Frischknecht [11] is as follows:…”

Section: Time Domain Apparent Resistivity Calculationsmentioning

confidence: 99%

Study of apparent resistivity imaging testing of the corrosion of buried metal pipelines

Zhou¹,

Shi²,

Hu³

2014

Insight

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The corrosion of buried metal pipelines can result in potentially fatal personal injuries and economic losses. In this paper, a transient electromagnetic method is used for the non-destructive testing of in-service buried metal pipelines in a trenchless state. We solve the implicit function equation to obtain the time domain apparent resistivity, which is timedepth transferred based on the smoke ring inversion theory. We then obtain a profile map of the apparent resistivity distribution of the buried medium to display the corrosion positions and the corresponding degree. The test results for the corrosion positions are verified as being generally consistent with the actual corrosion situation, only producing errors with regard to the corrosion boundary positioning. The results demonstrate that the transient electromagnetic method is a valid and practical method for testing of the corrosion of buried metal pipelines.

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“…CXir ability to interpret TDEM soundings was improved through use of asymptotic methods for calculation of the fields at very late times, double precision filters, a new, more convenient method for computation and display of results for forward modeling, and development of hardware and software for transfer, processing, and display of data in field (Anderson, 1983 andBradley and Raab, 1983;and Raab and Frischknecht, 1983). An efficient program for calculation of the fields inside and outside of a large rectangular loop was developed (Anderson, 1984b).…”

Section: Progress;mentioning

confidence: 99%

U.S. Geological Survey research in radioactive waste disposal - Fiscal years 1983, 1984, and 1985

Dinwiddie¹,

Trask²

1986

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The report summarizes progress on geologic and hydrologic research related to the disposal of radioactive wastes. The research is described according to whether it is related most directly to: (1) high-level and transuranic wastes, (2) low-level wastes, or (3) uranium mill tailings. Included is research applicable to the identification and geohydrologic characterization of waste-disposal sites, to investigations of specific sites where wastes have been stored, and to studies of regions or environments where wastedisposal sites might be located. A significant part of the activity is concerned with techniques and methods for characterizing disposal sites and studies of geologic and hydrologic processes related to the transport and (or) retention of waste radionuclides.

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Desktop computer processing of coincident and central loop time domain electromagnetic data

Cited by 17 publications

References 5 publications

Transient electromagnetic response of a three‐dimensional body in a layered earth

Transient electromagnetic response of a three‐dimensional body in a layered earth

Study of apparent resistivity imaging testing of the corrosion of buried metal pipelines

U.S. Geological Survey research in radioactive waste disposal - Fiscal years 1983, 1984, and 1985

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