Print Email Facebook Twitter Capacitively coupled EM sensors integrated in non-corrosive casings for longterm CSEM monitoring Title Capacitively coupled EM sensors integrated in non-corrosive casings for longterm CSEM monitoring Author Drijkoningen, G.G. (TU Delft Applied Geophysics and Petrophysics) Ravilov, M. (TU Delft Applied Geophysics and Petrophysics) Heller, H.K.J. (TU Delft Lab Geoscience and Engineering) van Beek, C. (TU Delft EMSD CE&G) Date 2024 Abstract We present a development of capacitively coupled EM sensors integrated in non-corrosive casings for permanent CSEM monitoring in boreholes. Capacitive sensors are required to detect low-frequency (diffusive-field) signals where voltage measurements fail and ammeters need to be used. The permanent installation in boreholes necessitates surface placement of the electronic components to ensure their longevity and accessibility. An issue is that small current signals need to be transferred over a large distance via cables whose capacitances are larger than the ones from the sensors, so a circuit of a Zero-Resistance Ammeter with Integrator (ZRA-I) was developed for annihilating the cable-capacitance effect. Via modelling, lab and small-scale field testing, we were able to show that capacitive sensors with ZRA-I electronics worked well: although the desired signal is slightly decreased compared to the one from galvanically coupled sensors, the signal-to-noise ratios are comparable, for the frequencies used. So we show that capacitive sensors can successfully be integrated in composite casings and, with the proper sensor electronics, can well be used for permanent CSEM monitoring in boreholes. To reference this document use: http://resolver.tudelft.nl/uuid:4c42fec8-dcb4-4613-815d-412f31bb25a9 DOI https://doi.org/10.3997/2214-4609.2024101491 Embargo date 2024-12-10 Event 85th EAGE Annual Conference & Exhibition 2024, 2024-06-10 → 2024-06-13, NOVA Spektrum Convention Centre, Oslo, Lillestrøm, Norway Bibliographical note Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Part of collection Institutional Repository Document type conference paper Rights © 2024 G.G. Drijkoningen, M. Ravilov, H.K.J. Heller, C. van Beek Files file embargo until 2024-12-10