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- Volume 38, Issue 10, 2020
First Break - Volume 38, Issue 10, 2020
Volume 38, Issue 10, 2020
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Exploring Kiruna iron ore fields with large-scale, semi-airborne, controlled-source electromagnetics
Authors M. Smirnova, N. Juhojuntti, M. Becken and M. SmirnovAbstractThe Kiruna mine is the largest underground iron ore mine in the world and provides a large portion of the iron ore produced within the EU. To facilitate the mineral exploration for such deep deposits, a novel semi-airborne controlled-source electromagnetic (CSEM) system was developed in the DESMEX project. In this approach, the transmitter is positioned on the ground, while the magnetic field is measured airborne with the support of additional ground observations of five components of the EM field. Such a set-up takes advantage of both ground and airborne techniques. High-moment transmitters are installed on the Earth’s surface, enabling injection of strong primary EM fields in the subsurface. The airborne receivers in turn ensure efficient, fast and spatially dense surveying. The semi-airborne EM system was validated in several field experiments in Germany. However, none of the tests were done at an active mineral exploration site. Here, we present the first results of the semi-airborne EM survey conducted at the Per Geijer iron ore deposit near Kiruna to explore the spatial and depth distribution of the ore body. The sophisticated 3D conductivity model matches the well-known surface geology and other geophysical information yet brings new insights into the general model of the ore body.
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Choice of decomposition in multispectral coherence computation
Authors Satinder Chopra and Kurt J. MarfurtAbstractThe iconic coherence attribute generally computed on the full-bandwidth seismic data has been used for 25 years to delineate structural and stratigraphic subsurface geometric features. More recently, multispectral coherence has been introduced to not only better define the more prominent features, but also more subtle features that may be poorly imaged by traditional broadband coherence attribute displays. Multispectral coherence generation utilizes the spectrally decomposed seismic data in the form of complex voice components within the seismic bandwidth. There are various methods available for spectral decomposition of seismic data, including the continuous wavelet transform, complex matching pursuit and the maximum entropy methods. In addition, a nonlinear spectral probe algorithm is also available and could be utilized for multispectral coherence generation. With all these methods available with the seismic interpreter, a question that pops up is which of these methods could be utilized for a more effective generation of multispectral coherence attribute. We first discuss multispectral coherence itself and its generation and follow that with a description of the different spectral decomposition methods mentioned above. Next, we generate spectral voice components and spectral probe components on two seismic data volumes from northeast British Columbia, Canada, and put them through multispectral coherence generation. A comparative performance of the different methods is then evaluated in terms of the multispectral coherence displays. Finally, some conclusions are drawn from the complete exercise.
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Planning deep subsurface CO2 storage monitoring for the Norwegian full-scale CCS project
Authors Anne-Kari Furre, Renata Meneguolo, Laurence Pinturier and Knut BakkeAbstractMonitoring injected CO2 is a regulatory requirement to assure safe storage and is also an important tool to optimize injection operations and confirm storage volumes. We will present the monitoring plan for the Norwegian full-scale CO2 project, particularly focusing on the subsurface monitoring. The CO2 will be injected into a deep saline aquifer at approximately 2700 m depth, located approximately 80 km offshore the western coast of Norway. Monitorability, cost and assessing leakage risk at the selected injection site were all important components in designing the optimal monitoring programme, which is aimed at proving conformance (CO2 plume behaving in accordance with predictions) and containment (no leakage out of the storage complex). The monitoring programme is separated into planned and triggered monitoring components. The planned component consists of down-hole monitoring of the well and near well area, and seismic monitoring (active and passive) of the larger subsurface area. In the case where the planned monitoring indicates non-conformance or non-containment, additional monitoring actions may be triggered. This contingency monitoring will be tailored to the specific case at hand and may consist of components of subsurface monitoring and/or of environmental surveys if there are indications of a risk of release to seabed.
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Volumes & issues
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)