Improvement in Time-domain IP Data Quality with Multi-electrode Systems by Separating Current and Potential Cables

Författare

Torleif Dahlin
Virginie Leroux

Summary, in English

Good quality time-domain IP data can be obtained using multi-electrode resistivity-IP equipment and standard electrode cable layouts at sites with favourable electrode contact. High contact resistances often result in low signal levels and capacitive coupling problems making the IP signals drown in noise. We tested an approach for measuring with separated cable spreads for current transmission and potential measurement with an instrument with transmitter, receiver and relay switch housed in the same box. Stainless electrodes and standard non-shielded multi-electrode cables with were used throughout. Data quality assessment was done via pseudosections, IP decay curves and full waveform plots. The results show that it is possible to improve the IP data quality at a site with unfavourable electrode grounding conditions. The results suggest that most of the coupling problems arise in the multi-core electrode cables, and that the problems can be reduced dramatically by separating the cable spreads for transmitting current and measuring potentials. The procedure used is relatively simple and applicable for current field measurements. Inversion of the recorded data results in low residuals and produces models that fit well with the geology at the site, although more detailed information would be needed to fully explain the observed phenomena. ...

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