The Generalized Electrosounding Method for Sedimentary Basin Exploration [microform] PDF Download

Author: J. Scott (John Scott) Holladay
Publisher: National Library of Canada
ISBN: 9780315397484
Category :
Languages : en
Pages : 0

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Book Description
Galvanic resistivity and electromagnetic induction sounding are presently the standard techniques for mapping the electrical structure of sedimentary basins. Taken in isolation, these methods have reached the limits of their interpretational accuracy, which can be only marginally improved by refinement of instrumental accuracy or field procedure. The Generalized Electrosounding (GES) method synthesizes the galvanic resistivity and electromagnetic techniques of sounding/profiling to utilize the wealth of information present in high-precision, broadband (0.05 Hz to 5 kHz) electric and magnetic field measurements made in the vicinity of a grounded controlled source. Analysis of these measurements should permit resolution of thin layer properties and apparent aeolotropy, which are not normally resolved by conventional electroprospecting datasets. A prototype measurement system was designed and constructed to investigate the practical acquisition of GES data. Analysis of data obtained with this system during field tests indicates that the instrumentation problem is now thoroughly understood. The principal obstacle to the use of GES for mapping geological structure and formation aeolotropy is "geological noise," a consequence of spatial undersampling of the measured fields. The most promising strategy for control of geological noise requires spatial "filtering" through the use of sensing dipoles which are large with respect to the receiver station spacing. Another feature which distinguishes G ES from conventional electroprospecting methods is the degree of possible redundancy in the data. This possible redundancy, which is a result of measuring both electric and magnetic field components over a wide range of frequencies and spatial offsets, is particularly useful in identifying non-stratified structure which might otherwise be misinterpreted as variations in stratigraphy.