Introduction to Controlled-Source Electromagnetic Methods

Ziolkowski, Anton; Slob, Evert

doi:10.1017/9781107415904

Cited by 6 publications

(3 citation statements)

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“…MT can achieve a great depth of investigation by measuring the sub-surface response to naturally occurring EM fields [25]; however, MT measurements suffer from a low signal-to-noise ratio (SNR) in urban environments [26,27], and may not be able to detect small resistivity changes due to variations in MT fields [28]. The CSEM relies on artificial sources of EM fields to investigate the electrical resistivity of the sub-surface to a depth of a few kilometres [29,30]. CSEM fields suffer from less variation due to the high repeatability of the source fields, and are characterised by high SNR due to the high source power [31].…”

Section: Introductionmentioning

confidence: 99%

Feasibility Study of Controlled-Source Electromagnetic Method for Monitoring Low-Enthalpy Geothermal Reservoirs

Eltayieb,

Werthmüller,

Drijkoningen

et al. 2023

Applied Sciences

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Tracking temperature changes by measuring the resulting resistivity changes inside low-enthalpy reservoirs is crucial to avoid early thermal breakthroughs and maintain sustainable energy production. The controlled-source electromagnetic method (CSEM) allows for the estimation of sub-surface resistivity. However, it has not yet been proven that the CSEM can monitor the subtle resistivity changes typical of low-enthalpy reservoirs. In this paper, we present a feasibility study considering the CSEM monitoring of 4–8 Ω·m resistivity changes in a deep low-enthalpy reservoir model, as part of the Delft University of Technology (TU Delft) campus geothermal project. We consider the use of a surface-to-borehole CSEM for the detection of resistivity changes in a simplified model of the TU Delft campus reservoir. We investigate the sensitivity of CSEM data to disk-shaped resistivity changes with a radius of 300, 600, 900, or 1200 m at return temperatures equal to 25, 30, …, 50 °C. We test the robustness of CSEM monitoring against various undesired effects, such as random noise, survey repeatability errors, and steel-cased wells. The modelled differences in the electric field suggest that they are sufficient for the successful CSEM detection of resistivity changes in the low-enthalpy reservoir. The difference in monitoring data increases when increasing the resistivity change radius from 300 to 1200 m or from 4 to 8 Ω·m. Furthermore, all considered changes lead to differences that would be detectable in CSEM data impacted by undesired effects. The obtained results indicate that the CSEM could be a promising geophysical tool for the monitoring of small resistivity changes in low-enthalpy reservoirs, which would be beneficial for geothermal energy production.

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Section: Introductionmentioning

confidence: 99%

Feasibility Study of Controlled-Source Electromagnetic Method for Monitoring Low-Enthalpy Geothermal Reservoirs

Eltayieb,

Werthmüller,

Drijkoningen

et al. 2023

Applied Sciences

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“…Good results have been achieved in geophysical prospecting of deep-seated metallic minerals, conventional oil and gas, shale gas, engineering geology, coal mine water disasters, and other areas. [21][22][23][24] At present, the transmission power of the pseudorandom signal transmitter is 100 kW and 30 kW in the fields of medium and shallow metal mineral resources detection, coal field water damage detection, and other fields. For deep exploration, such as searching for volcanic reservoirs, the resistivity of the oil area is very low, generally ranging from a few ohms to a dozen ohms, with the reservoir generally below 4 km.…”

Section: Introductionmentioning

confidence: 99%

“…The practical results in recent years have proved that the pseudorandom frequency‐domain electromagnetic method has achieved large depth detection under the premise of ensuring high precision and efficiency. Good results have been achieved in geophysical prospecting of deep‐seated metallic minerals, conventional oil and gas, shale gas, engineering geology, coal mine water disasters, and other areas 21‐24 …”

Section: Introductionmentioning

confidence: 99%