Elastic and Frictional Properties of Fault Zones in Reservoir-Scale Hydro-Mechanical Models—A Sensitivity Study

Treffeisen, Torben; Henk, Andreas

doi:10.3390/en13184606

Cited by 3 publications

(2 citation statements)

References 65 publications

(104 reference statements)

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“…The here investigated range from E =15 GPa to 0.125 GPa covers a large material property range. According Treffeisen and Henk (2020a), the amount of Young's modulus contrast have a strong impact on the resulting stress perturbation. Overall, this method did not provide a stress pattern like the contact surface method.…”

Section: Discontinuity Approach: Contact Elementsmentioning

confidence: 99%

“…Usually, the key driver between intact rock and the fault using the Mohr-Coulomb-failure criteria is not the friction coefficient, but the cohesion. Even from the modelling perspective, cohesion have the largest impact (Treffeisen and Henk, 2020a) on the stress state. Therefore the models with elements with elasto-plastic rheology use the same friction (ϕ =30 • , or µ = 0.58), but a very low cohesion C =0.1 kPa for the fault zone, in contrast of C =500 kPa outside this area.…”

Section: Cohesion Variation Within the 3-d Elementsmentioning

confidence: 99%

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Impact of faults on the remote stress state

Reiter

Heidbach

Ziegler

2023

Preprint

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Abstract. The impact of faults on the contemporary stress field in the upper crust has been discussed in various studies. Data and models clearly show that there is an impact, but so far, a systematic study that quantifies the impact as a function of distance to the fault is missing. As there is a lack of dense data, we use here a series of generic 3-D-models to investigate which component of the 3-D-stress tensor is affected at what distance to the fault. Our focus is on the far-field beyond hundreds of meters from the fault. The models test different approaches to implement faults, different material properties, different boundary conditions, variable orientation, and size of the fault. The results of our study show that beyond 1.000 m distance to the fault, the displacements along the fault and its strength contrast neither leaves an imprint on the orientation of the stress tensor nor in the magnitude of the principal stresses in the far field. This finding agrees with robust data from either stress magnitude measurements or areas where high-quality and high-resolution data on the change in orientation of the stress tensor are available. The latter shows often continuous and gradual rotation of the stress tensor orientation over lateral spatial scales of 10 km or larger. These rotations cannot be attributed to faults as they only have an impact on scales <1 km down to several meters only, as observed in numerous boreholes. Thus, we postulate that most stress orientation changes that are assigned to faults may have a different source.

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Section: Discontinuity Approach: Contact Elementsmentioning

confidence: 99%

Section: Cohesion Variation Within the 3-d Elementsmentioning

confidence: 99%

Impact of faults on the remote stress state

Reiter

Heidbach

Ziegler

2023

Preprint

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How pore pressure changes affect stress and strain in fault zones with complex internal structure – Insights from hydromechanical modelling

Treffeisen

Henk

2023

Journal of Structural Geology

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Impact of faults on the remote stress state

Reiter,

Heidbach,

Ziegler

2024

Solid Earth

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Abstract. The impact of faults on the contemporary stress field in the upper crust has been discussed in various studies. Data and models clearly show that there is an effect, but so far, a systematic study quantifying the impact as a function of distance from the fault is lacking. In the absence of data, here we use a series of generic 3-D models to investigate which component of the stress tensor is affected at which distance from the fault. Our study concentrates on the far field, located hundreds of metres from the fault zone. The models assess various techniques to represent faults, different material properties, different boundary conditions, variable orientation, and the fault's size. The study findings indicate that most of the factors tested do not have an influence on either the stress tensor orientation or principal stress magnitudes in the far field beyond 1000 m from the fault. Only in the case of oblique faults with a low static friction coefficient of μ=0.1 can noteworthy stress perturbations be seen up to 2000 m from the fault. However, the changes that we detected are generally small and of the order of lateral stress variability due to rock property variability. Furthermore, only in the first hundreds of metres to the fault are variations large enough to be theoretically detected by borehole-based stress data when considering their inherent uncertainties. This finding agrees with robust stress magnitude measurements and stress orientation data. Thus, in areas where high-quality and high-resolution data show gradual and continuous stress tensor rotations of >20∘ observed over lateral spatial scales of 10 km or more, we infer that these rotations cannot be attributed to faults. We hypothesize that most stress orientation changes attributed to faults may originate from different sources such as density and strength contrasts.

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Elastic and Frictional Properties of Fault Zones in Reservoir-Scale Hydro-Mechanical Models—A Sensitivity Study

Cited by 3 publications

References 65 publications

Impact of faults on the remote stress state

Impact of faults on the remote stress state

How pore pressure changes affect stress and strain in fault zones with complex internal structure – Insights from hydromechanical modelling

Impact of faults on the remote stress state

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