Time-lapse resistivity imaging: CSEM-data 3-D double-difference inversion and application to the Reykjanes geothermal field. Issue 3 (4th May 2021)

• Record Type: Journal Article
• Authors: Bretaudeau, F; Dubois, F; Bissavetsy Kassa, S-G; Coppo, N; Wawrzyniak, P; Darnet, M
• Is Part Of: Geophysical journal international. Volume 226:Issue 3(2021)
• Page Start: 1764
• Page End: 1782
• Publication Date: 2021-05-04
• Subjects: Controlled source electromagnetics (CSEM) -- Electromagnetic modelling -- Finite-difference methods -- Inverse theory; Geophysics -- Periodicals; 550
• DOI: 10.1093/gji/ggab172
• Languages: English
• ISSNs: 0956-540X

Abstract

SUMMARY: Time-lapse resistivity tomography bring valuable information on the physical changes occurring inside a geological reservoir. In this study, resistivity monitoring from controlled source electromagnetics (CSEM) data is investigated through synthetic and real data. We present three different schemes currently used to perform time-lapse inversions and compare these three methods: parallel, sequential and double difference. We demonstrate on synthetic tests that double difference scheme is the best way to perform time-lapse inversion when the survey parameters are fixed between the different time-lapse acquisitions. We show that double difference inversion allows to remove the imprint of correlated noise distortions, static shifts and most of the non-linearity of the inversion process including numerical noise and acquisition footprint. It also appears that this approach is robust against the baseline resistivity model quality, and even a rough starting resistivity model built from borehole logs or basic geological knowledge can be sufficient to map the time-lapse changes at their right positions. We perform these comparisons with real land time-lapse CSEM data acquired one year apart over the Reykjanes geothermal field.