Scale modelling of the parallel-line mode of operation of the Turam prospecting system and a comparison with the conventional mode
Physical scale modelling of the Parallel-line and Conventional modes of operation of the Turam prospecting system was performed. In the Parallel-line mode the long axis of the transmitter loop was placed perpendicular to the strike of a tabular target and traverse lines were run parallel to the transmitter . The receiver coils measured the vertical component of the magnetic field. This survey configuration causes a smaller primary field gradient along a traverse line than is caused by the Conventional configuration . The transmitter positioning enables multiple parallel targets to produce anomalies that are in proportion to their significance as conductors . Scale modelling in free-space conditions of the Parallel-line mode indicated the geometry of the anomalies caused by tabular targets of different dip angles and thicknesses and the positioning of the dominant current concentrations within such targets. Modelling of the Conventional mode allowed a comparison of the anomalies produced in the two systems to be made. The symmetrical energisation of a target in Parallel-line Turam causes a relatively simple target-anomaly spatial relationship, whereas the asymmetrical nature of the energisation in Conventional Turam causes a more complex relationship. The two modes of operation appear to be equally sensitive to different depth values of a target. The Parallel-line mode is sensitive to target strike variations and allows two targets to be visually resolved at a slightly smaller separation or larger depth than in the Conventional mode . Although the positioning of the transmitter with respect to the target in Parallel-line Turam suggests that the coupling between the primary field and the target is poor, the magnitude of the anomaly that may be measured in the Parallel-line mode is often larger than in the Conventional mode.
Bibliography: p. 521-523.
Cummins, C. (1986). Scale modelling of the parallel-line mode of operation of the Turam prospecting system and a comparison with the conventional mode (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/17193