Bringing complex salt structures into focus — A novel integrated approach

Buehnemann, Jan; Henke, Christian H.; Mueller, Christina; Krieger, Markus H.; Zerilli, Andrea; Strack, K. M.

doi:10.1190/1.1817278

Cited by 10 publications

(5 citation statements)

References 2 publications

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“…Contrary to other salt structures in the NEGB that are usually imaged as high resistivity bodies with MT (e.g. Buehnemann et al 2002), Fig. 8 shows a resistivity for the Zechstein evaporites comparable to that of the overlaying Lower Triassic sediments.…”

Section: -D Inversion Resultsmentioning

confidence: 75%

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A target-oriented magnetotelluric inversion approach for characterizing the low enthalpy Groß Schönebeck geothermal reservoir

Muñoz¹,

Ritter²,

Moeck³

2010

Geophysical Journal International

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S U M M A R YElectrical conductivity is a key parameter for the exploration and characterization of geothermal reservoirs as hot mineralized formation water of active geothermal areas usually exhibits significantly higher conductivity than the surrounding host rock. Here we present results of a magnetotelluric (MT) exploration experiment carried out in the vicinity of the Groß Schönebeck geothermal test site in Northern Germany, where a doublet system of two 4.3-km deep boreholes was drilled to establish an in situ laboratory to investigate the potential for geothermal energy production. Classical 2-D smooth inversion of the MT data, recorded along two profiles, reveals a shallow conductive structure in good agreement with information from regional geology and seismic images. However, at the northernmost part of the profiles, the conductivity models reveal deep-reaching conductive structures, which appear uncorrelated with existing (geophysical or geological) data. Incorporating information from seismics as independent constraints for MT inversions allows us to examine the model space rigorously but target oriented. Employing so-called tear-zone inversions we can effectively derive an alternative class of models, which are consistent with the MT observations but also with the other data sets. We speculate that the zones of high conductivity imaged at reservoir depth are related areas of reduced thickness of the overlaying evapourite layer. The enhanced conductivity can be explained by a higher fracture density in anhydritic layers and/or generally lower resistivity of the pore fluid.

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Section: -D Inversion Resultsmentioning

confidence: 75%

“…Contrary to other salt structures in the NEGB that are usually imaged as high resistivity bodies with MT (e.g. Buehnemann et al . 2002), Fig.…”

Section: Introductionmentioning

confidence: 88%

A target-oriented magnetotelluric inversion approach for characterizing the low enthalpy Groß Schönebeck geothermal reservoir

Muñoz¹,

Ritter²,

Moeck³

2010

Geophysical Journal International

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“…Salt domes of the NGB are usually very resistive (Buehnemann et al . ). Although, it is plausible that influx of meteoric water has led to the formation of brine around the salt dome, which would make its bulk resistivity seem lower.…”

Section: Discussionmentioning

confidence: 97%

The electrical conductivity of Posidonia black shales — from magnetotelluric exploration to rock samples

Adão

Ritter

Spangenberg

2015

Geophysical Prospecting

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A B S T R A C TWe carried out a magnetotelluric field campaign in the South-East Lower Saxony Basin, Germany, with the main goal of testing this method for imaging regional Posidonia black shale sediments. Two-dimensional inversion results of the magnetotelluric data show a series of conductive structures correlating with brine-saturated sediments but also with deeper, anthracitic Westphalian/Namurian coals. None of these structures can be directly related with the Posidonia black shale, which appears to be generally resistive and therefore difficult to resolve with the magnetotelluric method. This assumption is supported by measurements of electrical resistivity on a set of Posidonia shale samples from the Hils syncline in the Lower Saxony basin. These rock samples were collected in shallow boreholes and show immature (0.53% Ro), oil (0.88% Ro), and gas (1.45% Ro) window thermal maturities. None of the black shale samples showed low electrical resistivity, particularly those with oil window maturity show resistivity exceeding 10 4 m. Moreover, we could not observe a direct correlation between maturity and electrical resistivity; the Harderode samples showed the highest resistivity, whereas the Haddessen samples showed the lowest. A similar trend has been seen for coals in different states of thermal maturation. Saturation of the samples with distilled and saline water solutions led to decreasing electrical resistivity. Moreover, a positive correlation of electrical resistivity with porosity is observed for the Wickensen and Harderode samples, which suggests that the electrical resistivity of the Posidonia black shale is mainly controlled by porosity.

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“…The following robust regression estimation having highest breakdown point is used to derive final parameter estimates. It includes the Siegel estimator [86] which is based on repeated median algorithm with a reduced M-estimator. This robust processing scheme improves data quality and results in high quality estimations of impedance and tipper despite contamination by industrial noise.…”

Section: Mt Data Processingmentioning

confidence: 99%

An Array Multi-Physics Acquisition System with Focus on Reservoir Monitoring for the Energy Transition

2022

EESRR

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During the energy transition, geophysics will need to focus on novel green energy applications and to reduce the carbon footprint of hydrocarbon production. For both reservoir, monitoring is important, in particular dynamic monitoring of reservoir fluids. For renewable energies such as geothermal, electromagnetics has always been the geophysical ‘work horse’, while mostly microseismic has been used for monitoring. For hydrocarbon reservoirs, added value toward ZERO carbon footprint is obtained by increasing the recovery factor by of 30-40 % and thus reducing the cost/carbon emission per produced barrel. In addition, CO2 is sequestered in brine saturated reservoirs and also needs to be monitored. We are addressing the fluid monitoring issue here for electromagnetics and are reviewing how hardware, methodology and application are interlinked to build a complete system. Various applications and case histories where the results can be verified by borehole logs support this. The key issue is that our measurement need to respond to geologic realistic Earth formations which are, generally speaking, anisotropic. We direct the entire design of the system in solving that problem with direc-tional sensitive measurements. Next, when we want to monitor reservoir change we require a repeatability and accuracy hereto not necessary. By carefully controlling the entire hardware design from sensor to applications stage this can be achieved and we can obtain log scale resolution from surface measurement which was hereto not possible.

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Bringing complex salt structures into focus — A novel integrated approach

Cited by 10 publications

References 2 publications

A target-oriented magnetotelluric inversion approach for characterizing the low enthalpy Groß Schönebeck geothermal reservoir

A target-oriented magnetotelluric inversion approach for characterizing the low enthalpy Groß Schönebeck geothermal reservoir

The electrical conductivity of Posidonia black shales — from magnetotelluric exploration to rock samples

An Array Multi-Physics Acquisition System with Focus on Reservoir Monitoring for the Energy Transition

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