The contribution of magnetotellurics to an improved understanding of the geological evolution of the North German Basin review and new results

Hoffmann, N.; Hengesbach, Laska; Friedrichs, Bernhard; Brink, Heinz-Jürgen

doi:10.1127/1860-1804/2008/0159-0591

Cited by 11 publications

(13 citation statements)

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“…With increasing depths, the overall resistivity values are low, ranging between 1 Ωm and 50 Ωm, which is common for the North German Basin (e.g., Hoffmann et al . ). The resistivity structure obtained from the 2D inversion of the MT data agrees well with well‐log data of a nearby borehole, located approximately 1 km SE of the centre of the profile (Fig.…”

Section: Background Resistivity Structure Of the Bockstedt Oil Fieldmentioning

confidence: 97%

Controlled‐source electromagnetic monitoring of reservoir oil saturation using a novel borehole‐to‐surface configuration

Tietze

Ritter

Veeken³

2015

Geophysical Prospecting

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To advance and optimize secondary and tertiary oil recovery techniques, it is essential to know the areal propagation and distribution of the injected fluids in the subsurface. We investigate the applicability of controlled‐source electromagnetic methods to monitor fluid movements in a German oilfield (Bockstedt, onshore Northwest Germany) as injected brines (highly saline formation water) have much lower electrical resistivity than the oil within the reservoir. The main focus of this study is on controlled‐source electromagnetic simulations to test the sensitivity of various source–receiver configurations. The background model for the simulations is based on two‐dimensional inversion of magnetotelluric data gathered across the oil field and calibrated with resistivity logs. Three‐dimensional modelling results suggest that controlled‐source electromagnetic methods are sensitive to resistivity changes at reservoir depths, but the effect is difficult to resolve with surface measurements only. Resolution increases significantly if sensors or transmitters can be placed in observation wells closer to the reservoir. In particular, observation of the vertical electric field component in shallow boreholes and/or use of source configurations consisting of combinations of vertical and horizontal dipoles are promising. Preliminary results from a borehole‐to‐surface controlled‐source electromagnetic field survey carried out in spring 2014 are in good agreement with the modelling studies.

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Section: Background Resistivity Structure Of the Bockstedt Oil Fieldmentioning

confidence: 97%

Controlled‐source electromagnetic monitoring of reservoir oil saturation using a novel borehole‐to‐surface configuration

Tietze

Ritter

Veeken³

2015

Geophysical Prospecting

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“…also hint towards compacted high-density strata and/or integrated granulitized/eclogitized lower crust which was uplifted to lower depths (Brink, 2013). New magnetotelluric measurements (Hoffmann et al, 2008;Brink, 2010Brink, , 2012 show no indication of a plutonic body exhibiting low electric conductivities and high electric impedance, respectively, above 15 km depth. Brink (2013), therefore, proposed further alternative scenarios which could be held responsible for the observed anomalous attributes.…”

Section: Intrusion Vs Inversion -Bramsche Massifmentioning

confidence: 96%

“…velocities in that refractor, originally interpreted as the roof of the intrusion, might also indicate Lower Carboniferous/Upper Devonian shelf carbonates (Hoffmann et al, 2008;Doornenbal & Stevenson, 2010) to which the observed seismic velocities would suit more. On top of these carbonates, Upper Carboniferous deposits with high organic content had been deposited.…”

Section: Intrusion Vs Inversion -Bramsche Massifmentioning

confidence: 97%

“…East of the Netherlands (Polish Trough, North German and Lower Saxony basins) the inversion ceased during the Upper Cretaceous to earliest Tertiary. In the Netherlands (Broad Fourteens and West Netherlands basins), it continued until Upper Oligocene to Lower Miocene times (van Hoorn, 1987;Ziegler, 1990;Ziegler et al, 1995;de Lugt et al, 2003; which might be related to a delayed mechanical coupling of the collisional system towards the west, i.e. between the Pyrenean Orogeny and central Europe (Doornenbal & Stevenson, 2010).…”

Section: Geodynamic Evolutionmentioning

confidence: 99%

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Thermal evolution and shale gas potential estimation of the Wealden and Posidonia Shale in NW‐Germany and the Netherlands: a 3D basin modelling study

et al. 2015

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Sedimentary basins in NW-Germany and the Netherlands represent potential targets for shale gas exploration in Europe due to the presence of Cretaceous (Wealden) and Jurassic (Posidonia) marlstones/shales as well as various Carboniferous black shales. In order to assess the regional shale gas prospectivity of this area, a 3D high-resolution petroleum system model has been compiled and used to reconstruct the source-rock maturation based on calibrated burial and thermal histories. Different basal heat flow scenarios and accordingly, different high-resolution scenarios of erosional amount distribution were constructed, incorporating all major uplift events that affected the study area. The model delivers an independent 3D reappraisal of the tectonic and thermal history that controlled the differential geodynamic evolution and provides a high-resolution image of the maturity distribution and evolution throughout the study area and the different basins. Pressure, temperature and TOCdependent gas storage capacity and gas contents of the Posidonia Shale and Wealden were calculated based on experimentally derived Langmuir sorption parameters and newly compiled source-rock thickness maps indicating shale gas potential of the Lower Saxony Basin, southern Gifhorn Trough and West Netherlands Basin.

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“…The MT method is a passive remote sensing method that uses naturally occurring time variations of electromagnetic fields in Earth's atmosphere to resolve structures in Earth's crust and mantle, in terms of their electrical resistivity. Black shale and other organic‐rich rocks, e.g., coals, have been found in many parts of the world to coincide with zones of high conductivity (Jödicke ; Raab ; Hoffmann, Jödicke, and Horeshschi ).…”

Section: Introductionmentioning

confidence: 99%

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 contribution of magnetotellurics to an improved understanding of the geological evolution of the North German Basin review and new results

Cited by 11 publications

References 0 publications

Controlled‐source electromagnetic monitoring of reservoir oil saturation using a novel borehole‐to‐surface configuration

Controlled‐source electromagnetic monitoring of reservoir oil saturation using a novel borehole‐to‐surface configuration

Thermal evolution and shale gas potential estimation of the Wealden and Posidonia Shale in NW‐Germany and the Netherlands: a 3D basin modelling study

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

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