Gunnar Jansen

University of Bern

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Stephen A. Miller

University of Neuchâtel

Reza Sohrabi

University of Neuchâtel

Boris Galván

University of Neuchâtel

Adriano Mazzini

Institute for Energy Technology

C. Joubert

University of Neuchâtel

Thomas Heinze

Ruhr University Bochum

C. J. Ruhl

University of Tulsa

Benjamin Malvoisin

Institut des Sciences de la Terre

J. L. Rubinstein

United States Geological Survey

Cooperative Institutions

University of Neuchâtel

University of Bonn

Istituto Nazionale di Geofisica e Vulcanologia

Ruhr University Bochum

Norsk Hydro (Germany)

Friedrich Schiller University Jena

Czech Academy of Sciences, Institute of Geology

South China University of Technology

Czech University of Life Sciences Prague

KU Leuven

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Systematic study of the effects of mass and time scaling techniques applied in numerical rock mechanics simulations

Tectonophysics (2015)

Thomas Heinze Gunnar Jansen Boris Galván Stephen A. Miller

10.1016/j.tecto.2015.10.013

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Citations (13)

HULK - Simple and fast generation of structured hexahedral meshes for improved subsurface simulations

EGU General Assembly Conference Abstracts (2017)

Reza Sohrabi Gunnar Jansen Stephen A. Miller

Hexahedron

Source

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Fluid Pressure‐Triggered Foreshock Sequence of the 2008 Mogul Earthquake Sequence: Insights From Stress Inversion and Numerical Modeling

Journal of Geophysical Research Solid Earth (2019)

Gunnar Jansen C. J. Ruhl Stephen A. Miller

Abstract In Mogul west of Reno, Nevada, USA, in late February 2008 an earthquake sequence occurred that culminated in a magnitude 4.9 mainshock after a foreshock‐rich period lasting approximately 2 months on previously unidentified fault structures. In this article, we show that the foreshock sequence may have been driven by a fluid pressure intrusion. We use 1,082 previously calculated earthquake focal mechanisms to infer the local stress field as well as 1,408 relocated foreshock events to determine the required excess fluid pressure field in the source region of the Mogul earthquake sequence to trigger these events. A model of nonlinear pore pressure diffusion is used to model the fluid flow in a highly fractured subsurface. We find a strong correlation between high fluid pressure fronts and foreshock hypocenters, suggesting a natural fluid‐driven earthquake sequence.

Stress field

Sequence (biology)

10.1029/2018jb015897

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On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs

Geofluids (2017)

Gunnar Jansen Stephen A. Miller

Massive quantities of fluid are injected into the subsurface during the creation of an engineered geothermal system (EGS) to induce shear fracture for enhanced reservoir permeability. In this numerical thermoelasticity study, we analyze the effect of cold fluid injection on the reservoir and the resulting thermal stress change on potential shear failure in the reservoir. We developed an efficient methodology for the coupled simulation of fluid flow, heat transport, and thermoelastic stress changes in a fractured reservoir. We performed a series of numerical experiments to investigate the effects of fracture and matrix permeability and fracture orientation on thermal stress changes and failure potential. Finally, we analyzed thermal stress propagation in a hypothetical reservoir for the spatial and temporal evolution of possible thermohydraulic induced shear failure. We observe a strong influence of the hydraulic reservoir properties on thermal stress propagation. Further, we find that thermal stress change can lead to induced shear failure on nonoptimally oriented fractures. Our results suggest that thermal stress changes should be taken into account in all models for long-term fluid injections in fractured reservoirs.

Thermoelastic damping

Effective stress

10.1155/2017/4653278

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Citations (16)

HULK – Simple and fast generation of structured hexahedral meshes for improved subsurface simulations

Computers & Geosciences (2016)

Gunnar Jansen Reza Sohrabi Stephen A. Miller

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Basis (linear algebra)

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10.1016/j.cageo.2016.11.011

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Citations (6)

Injection‐Induced Earthquakes Near Milan, Kansas, Controlled by Karstic Networks

Geophysical Research Letters (2020)

C. Joubert Reza Sohrabi J. L. Rubinstein Gunnar Jansen Stephen A. Miller

Abstract Induced earthquakes from waste disposal operations in otherwise tectonically stable regions significantly increases seismic hazard. It remains unclear why injections induce large earthquakes on non‐optimally oriented faults kilometers below the injection horizon, particularly since fluids are not injected under pressure, but rather poured, into the well as observed in the Milan, Kansas area. Here we propose a mechanism for induced earthquakes whereby the karstic lower Arbuckle provides the short‐circuit that establishes a tens of MPa stepwise fluid pressure increase within the basement upon arrival of the hydraulic connection to the free surface and ultimately induce slip on the deeper fault. We investigate this scenario through modeling and mechanical analysis and show that earthquakes near Milan are likely induced by large (and sudden) fluid pressure changes when the karst network links two previously isolated hydrological systems.

Basement

10.1029/2020gl088326

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Citations (5)

Numerical modeling of the Lusi hydrothermal system: Initial results and future challenges

Marine and Petroleum Geology (2017)

Reza Sohrabi Gunnar Jansen Benjamin Malvoisin Adriano Mazzini Stephen A. Miller

Multiphase flow

10.1016/j.marpetgeo.2017.08.012

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Citations (6)

Corrigendum to “On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs”