• Block preconditioners for mixed-dimensional discretization of flow in fractured porous media 

      Budisa, Ana; Hu, Xiaozhe (Journal article; Peer reviewed, 2021)
      In this paper, we are interested in an efficient numerical method for the mixed-dimensional approach to modeling single-phase flow in fractured porous media. The model introduces fractures and their intersections as ...
    • Dimensional reduction of a fractured medium for a polymer EOR model 

      Dugstad, Martin Sandanger; Kumar, Kundan; Pettersen, Øystein (Journal article; Peer reviewed, 2021)
      Dimensional reduction strategy is an effective approach to derive reliable conceptual models to describe flow in fractured porous media. The fracture aperture is several orders of magnitude smaller than the characteristic ...
    • Efficient water table evolution discretization using domain transformation 

      Boon, Wietse; Balbarini, Nicola; Binning, Philip John; Nordbotten, Jan Martin (Peer reviewed; Journal article, 2017-02)
      Domain transformation methods are useful techniques for solving problems on non-stationary domains. In this work, we consider the evolution of the water table in an unconfined aquifer. This nonlinear, time-dependent problem ...
    • Fast robust optimization using bias correction applied to the mean model 

      Wang, Lingya; Oliver, Dean (Peer reviewed; Journal article, 2021)
      Ensemble methods are remarkably powerful for quantifying geological uncertainty. However, the use of the ensemble of reservoir models for robust optimization (RO) can be computationally demanding. The straightforward ...
    • Inexact linear solvers for control volume discretizations in porous media 

      Keilegavlen, Eirik; Nordbotten, Jan Martin (Peer reviewed; Journal article, 2014-12-03)
      We discuss the construction ofmulti-level inexact linear solvers for control volume discretizations for porous media. The methodology forms a contrast to standard iterative solvers by utilizing an algebraic hierarchy of ...
    • Iterative schemes for surfactant transport in porous media 

      Illiano, Davide; Pop, Iuliu Sorin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)
      In this work, we consider the transport of a surfactant in variably saturated porous media. The water flow is modelled by the Richards equations and it is fully coupled with the transport equation for the surfactant. Three ...
    • Iterative solvers for Biot model under small and large deformation 

      Borregales Reveron, Manuel Antonio; Kumar, Kundan; Nordbotten, Jan Martin; Radu, Florin Adrian (Journal article; Peer reviewed, 2021)
      We consider L-scheme and Newton-based solvers for Biot model under large deformation. The mechanical deformation follows the Saint Venant-Kirchoff constitutive law. Furthermore, the fluid compressibility is assumed to be ...
    • Marginalized iterative ensemble smoothers for data assimilation 

      Stordal, Andreas Størksen; Lorentzen, Rolf Johan; Fossum, Kristian (Journal article; Peer reviewed, 2023)
      Data assimilation is an important tool in many geophysical applications. One of many key elements of data assimilation algorithms is the measurement error that determines the weighting of the data in the cost function to ...
    • Open-source MATLAB implementation of consistent discretisations on complex grids 

      Lie, Knut-Andreas; Krogstad, Stein; Ligaarden, Ingeborg Skjelkvåle; Natvig, Jostein Roald; Nilsen, Halvor Møll; Skaflestad, Bård (Peer reviewed; Journal article, 2011-08-02)
      Accurate geological modelling of features such as faults, fractures or erosion requires grids that are flexible with respect to geometry. Such grids generally contain polyhedral cells and complex grid-cell connectivities. ...
    • PorePy: an open-source software for simulation of multiphysics processes in fractured porous media 

      Keilegavlen, Eirik; Berge, Runar Lie; Fumagalli, Alessio; Starnoni, Michele; Stefansson, Ivar; Varela, Jhabriel; Berre, Inga (Journal article; Peer reviewed, 2021)
      Development of models and dedicated numerical methods for dynamics in fractured rocks is an active research field, with research moving towards increasingly advanced process couplings and complex fracture networks. The ...
    • Robust iterative schemes for non-linear poromechanics 

      Borregales Reveron, Manuel Antonio; Radu, Florin Adrian; Kumar, Kundan; Nordbotten, Jan Martin (Peer reviewed; Journal article, 2018)
      We consider a non-linear extension of Biot’s model for poromechanics, wherein both the fluid flow and mechanical deformation are allowed to be non-linear. Specifically, we study the case when the volumetric stress and the ...
    • Sampling error distribution for the ensemble Kalman filter update step 

      Kovalenko, Andrey; Mannseth, Trond; Nævdal, Geir (Peer reviewed; Journal article, 2012)
      In recent years, data assimilation techniques have been applied to an increasingly wider specter of problems. Monte Carlo variants of the Kalman filter, in particular, the ensemble Kalman filter (EnKF), have gained significant ...
    • Sequential multilevel assimilation of inverted seismic data 

      Nezhadali, Mohammad; Bhakta, Tuhin; Fossum, Kristian; Mannseth, Trond (Journal article; Peer reviewed, 2023)
      We consider estimation of absolute permeability from inverted seismic data. Large amounts of simultaneous data, such as inverted seismic data, enhance the negative effects of Monte Carlo errors in ensemble-based Data ...
    • A simulation workflow for large-scale CO2 storage in the Norwegian North Sea 

      Lie, Knut-Andreas; Nilsen, Halvor Møll; Andersen, Odd; Møyner, Olav (Journal article, 2016-06)
      Large-scale CO2 injection problems have revived the interest in simple models, like percolation and vertically-averaged models, for simulating fluid flow in reservoirs and aquifers. A series of such models have been collected ...
    • A singularity removal method for coupled 1D–3D flow models 

      Gjerde, Ingeborg Gåseby; Kumar, Kundan; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2019)
      In reservoir simulations, the radius of a well is inevitably going to be small compared to the horizontal length scale of the reservoir. For this reason, wells are typically modelled as lower-dimensional sources. In this ...
    • Stable mixed finite elements for linear elasticity with thin inclusions 

      Boon, Wietse; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2021)
      We consider mechanics of composite materials in which thin inclusions are modeled by lower-dimensional manifolds. By successively applying the dimensional reduction to junctions and intersections within the material, a ...