HM Faults

Faults in Hydro-Mechanical Models

Faults have a major influence on the local tectonic stress field and may prove to be – depending on their hydraulic properties – either conduits or barriers to fluid flow. Consequently, an appropriate implementation of faults into numerical underground models is of utmost importance.

Facts about the project

PhD project: Torben Treffeisen +++ Duration: 01.10.2018 – 31.03.2021

Latest Research Results

FaultUpscalePy – A Prototype for AI-based Upscaling of Fault Zone Properties

How the geometry of a fault zone, including its complex internal structure consisting of damage zone and fault core respectively its heterogeneous material properties, can be portrayed within a finite element model remains a challenge. In particular, the scale difference between the internal details of the fault zone and typical element size of such reservoir models, ranging from tens to hundreds of meters, needs to be taken into account.

Modelling concept for the comparison of different approaches to implement faults in geomechanical reservoir models.
Modelling concept for the comparison of different approaches to implement faults in geomechanical reservoir models.

Too Development

FaultGeomPy – A Prototype for Fast and Easy Generation of Detailed Fault Zone Geometries
Spatial distribution of pore pressure, effective stress (S1,eff) and plastic strain along a fault zone with different fault geometry.
Spatial distribution of pore pressure, effective stress (S1,eff) and plastic strain along a fault zone with different fault geometry.

This dissertation project compares different possibilities to implement faults in finite element models of geological reservoirs. Using the example of generic fault zones, the influence of mesh geometry as well as element size and element type are observed in parameter studies. Moreover, concepts for upscaling of hydro-mechanical properties are acquired. From the results, practical recommendations for implementing faults and the appropriate selection of the hydro-mechanical properties regarding the fault zone are expected. Such true-to-life descriptions of faults in numerical models would allow more reliable predictions in regards to stress perturbations, fault reactivation by pore pressure changes and fluid flow.

Published Results

Elastic and Frictional Properties of Faults Zones in Reservoir-Scale Hydro-Mechanical Models
  • Treffeisen, T., Henk, A., 2021: AI-Based Comparison and Upscaling of Detailed to Homogenized Fault Zone Representations in Reservoir-Scale Hydro-Mechanical Simulations, In Proceedings of the 55th U.S. Rock Mechanics – Geomechanics Symposium, 18.-25. June 2021. Houston, Texas, USA.
  • Treffeisen, T. & Henk, A. 2020. Faults as Volumetric Weak Zones in Reservoir-Scale Hydro-Mechanical Finite Element Models – A Comparison Based on Grid Geometry, Mesh Resolution and Fault Dip. Energies 13, (10), 1-28.
  • Treffeisen, T. & Henk, A. 2020. Elastic and Frictional Properties of Fault Zones in Reservoir-Scale Hydro-Mechanical Models-A Sensitivity Study. Energies 13, (18), 1-27.
  • Treffeisen, T., Henk, A., 2020. Representation of faults in reservoir-scale geomechanical finite element models – A comparison of different modelling approaches, Journal of Structural Geology, 131, pp. 1-12.
  • Treffeisen, T., Henk, A., 2020. Comparison of Different Numerical Approaches and Grid Geometries to Represent Faults in Geomechanical Finite Element Reservoir Models, AAPG –ACE 2020, Houston, Texas, USA. (Poster Presentation).
  • Treffeisen, T., 2019. Representation of Faults as Homogenized Continuum in Reservoir-Scale Hydro-Geomechanical Finite Element Models – A Comparison Based on Fault Geometry and Heterogeneity Oral Presentation, SPE – Student Technical Conference, Aachen, Germany.
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