Numerical Modelling of Salt-Related Stress Decoupling in Sedimentary Basins–Motivated by Observational Data from the North German Basin

Ahlers, Steffen; Hergert, Tobias; Henk, Andreas

doi:10.3390/geosciences9010019

Cited by 11 publications

(8 citation statements)

References 42 publications

(46 reference statements)

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“…These detachment horizons can also result in the decoupling of the basement and overburden deformation during crustal compression. Similar vertical variations in the state of a stress regime have been observed in the eastern part of the Paris Basin [88], the eastern North German Basin (NGB) [87,89], and the Nile Delta [91].…”

Section: Discussionsupporting

confidence: 63%

“…Stress variation with depth can be explained by decoupling of the stress because of the existence of a ductile formation [87][88][89]. The ZFTB can be considered as a classic case for stress decoupling and a varying stress regime with depth in sedimentary basins due to several continuous highly ductile formations: the Precambrian Hormuz, Triassic Dashtak, and Miocene Gachsaran.…”

Section: Discussionmentioning

confidence: 99%

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Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

et al. 2021

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This study focuses on determining the orientation and constraining the magnitude of present-day stresses in the Dezful Embayment in Iran’s Zagros Fold and Thrust Belt. Two datasets are used: the first includes petrophysical data from 25 wells (3 to 4 km deep), and the second contains 108 earthquake focal mechanisms, mostly occurring in blind active basement faults (5 to 20 km deep). Formal stress inversion analysis of the focal mechanisms demonstrates that there is currently a compressional stress state ( in the basement. The seismologically determined SHmax direction is 37° ± 10°, nearly perpendicular to the strike of most faults in the region. However, borehole geomechanics analysis using rock strength and drilling evidence leads to the counterintuitive result that the shallow state of stress is a normal/strike-slip regime. These results are consistent with the low seismicity level in the sedimentary cover in the Dezful Embayment, and may be evidence of stress decoupling due to the existence of salt layers. The stress state situation in the field was used to identify the optimally oriented fault planes and the fault friction coefficient. This finding also aligns with the prediction Coulomb faulting theory in that the N-S strike-slip basement Kazerun Fault System has an unfavorable orientation for slip in a reverse fault regime with an average SW-NE SHmax orientation. These results are useful for determining the origin of seismic activity in the basin and better assessing fault-associated seismic hazards in the area.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

et al. 2021

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“…Data availability. The results of our model have been published and are publicly available at https://doi.org/10.48328/tudatalib-437 (see Ahlers et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

3D crustal stress state of Germany according to a data-calibrated geomechanical model

et al. 2021

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Abstract. The contemporary stress state in the upper crust is of great interest for geotechnical applications and basic research alike. However, our knowledge of the crustal stress field from the data perspective is limited. For Germany basically two datasets are available: orientations of the maximum horizontal stress (SHmax) and the stress regime as part of the World Stress Map (WSM) database as well as a complementary compilation of stress magnitude data of Germany and adjacent regions. However, these datasets only provide pointwise, incomplete and heterogeneous information of the 3D stress tensor. Here, we present a geomechanical–numerical model that provides a continuous description of the contemporary 3D crustal stress state on a regional scale for Germany. The model covers an area of about 1000×1250 km2 and extends to a depth of 100 km containing seven units, with specific material properties (density and elastic rock properties) and laterally varying thicknesses: a sedimentary unit, four different units of the upper crust, the lower crust and the lithospheric mantle. The model is calibrated by the two datasets to achieve a best-fit regarding the SHmax orientations and the minimum horizontal stress magnitudes (Shmin). The modeled orientations of SHmax are almost entirely within the uncertainties of the WSM data used and the Shmin magnitudes fit to various datasets well. Only the SHmax magnitudes show locally significant deviations, primarily indicating values that are too low in the lower part of the model. The model is open for further refinements regarding model geometry, e.g., additional layers with laterally varying material properties, and incorporation of future stress measurements. In addition, it can provide the initial stress state for local geomechanical models with a higher resolution.

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“…Hence, the development of improved forward models that directly predict salt diapir shapes under various conditions becomes very valuable for structural geologists. In addition, whenever drilling in and around salt is performed, quantifying the stress field inside and especially around salt domes (in terms of the magnitudes and directions of principal stresses) is of great interest, because of its effects on well‐bore stability and borehole collapse 7‐10 …”

Section: Introductionmentioning

confidence: 99%

A blended transient/quasistatic Lagrangian framework for salt tectonics simulations with stabilized tetrahedral finite elements

Scovazzi

Colomés

Abboud

et al. 2021

Numerical Meth Engineering

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We propose a Lagrangian solid mechanics framework for the simulation of salt tectonics and other large‐deformation geomechanics problems at the basin scale. Our approach relies on general elastic‐viscoplastic constitutive models to characterize the deformation of geologic strata, in contrast with the majority of published works on the subject, which utilize nonlinear Stokes flow models. By means of multiscale asymptotics, we also show that the inertia term in the momentum balance equation can be safely neglected, if the goal is to track the Earth's crust deformation over long periods of time. Our time integration strategy is a blended transient/quasistatic approach, in that it consists of a constitutive stress update, subject to the constraint that the stresses must satisfy static equilibrium. In addition, we use stabilized finite element methods specifically built for triangular and tetrahedral grids, which can also perform well under incompressibility constraints. Our approach offers computational geologists the following advantages: (1) improved flexibility in the choice of subsurface constitutive models with respect to the nonlinear Stokes flow; (2) improved efficiency over transient dynamics algorithms used in this context in the past, which are forced to resolve seismic events over geologic time scales; and (3) improved robustness in large strain computations over quadrilateral/hexahedral finite elements. We demonstrate the performance of the proposed approach with simulations of passive diapirism.

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Numerical Modelling of Salt-Related Stress Decoupling in Sedimentary Basins–Motivated by Observational Data from the North German Basin

Cited by 11 publications

References 42 publications

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

3D crustal stress state of Germany according to a data-calibrated geomechanical model

A blended transient/quasistatic Lagrangian framework for salt tectonics simulations with stabilized tetrahedral finite elements

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