Computational Geosciences (COMPUTAT GEOSCI )

Publisher: Springer Verlag


Accurate and efficient imaging of subsurface structure and modeling of processes in the subsurface require multidisciplinary collaboration among mathematicians engineers chemists physicists and geoscientists. Presently there exists no journal whose main objective is to provide a platform for interaction among these diverse scientific groups. To remedy this we propose to establish a new journal Computational Geosciences . The aim of this international journal is to facilitate the exchange of ideas across the disciplines and among universities and industrial and governmental laboratories. Computational Geosciences will publish high quality papers on mathematical modeling simulation data analysis imaging inversion and interpretation with applications in the geosciences. The themes and application areas to be covered include reservoir and environmental engineering hydrology geochemistry geomechanics seismic and electromagnetic imaging geostatistics and reservoir/aquifer characterization and high performance parallel computing. More specifically Computational Geosciences welcomes contributions concerning for example bioremediation diffusion and dispersion geology and geostatistics scale up multiphase flow and reactive transport geophysical imaging and inversion methods seismic and electromagnetic modeling numerical methods and parallel computing. Both theoretical and applied scientists are invited to participate. Computational Geosciences focuses mainly on quantitative aspects of models describing transport processes in permeable media. It is targeted at petroleum engineers hydrologists quantitative environmental engineers soil physicists soil and geochemists applied mathematicians geologists and seismologists.

Impact factor 1.61

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    Computational Geosciences website
  • Other titles
    Computational geosciences (Online), CG
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    Periodical, Internet resource
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    Internet Resource, Computer File, Journal / Magazine / Newspaper

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Springer Verlag

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Publications in this journal

  • Janek Greskowiak, Jack Gwo, Diederik Jacques, Jun Yin, K. Ulrich Mayer
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    ABSTRACT: Nonequilibrium surface complexation reactions have been found to substantially affect U(VI) transport in natural porous media both in laboratory and field scale experiments. Nonequilibrium sorption behavior occurs on multiple time scales and is a result of diffusion-limited transport in immobile intra-grain and intra-aggregate pore water. Experimental data on U(VI) transport was success- fully described with a recently developed reactive transport model that accounted for the nonequilibrium adsorption processes through the formulation of a multi-rate sur- face complexation model treating surface complexation as kinetic reactions. In the present work, a benchmark problem set has been developed for testing existing or newly devel- oped reactive transport codes on their capability to simulate multi-rate surface complexation and dual-domain multi- component reactive transport of U(VI). The benchmark problem consists of three individual component problems on the basis of previous studies investigating the desorption of U(VI) from radionuclide-contaminated sediment from the Hanford 300A site, Washington, USA. Starting with a single-domain model considering constant hydrochemical conditions (component problem 1), the complexity of the model was stepwise increased. In the component problem 2 dual-domain first-order mass transfer was added. The prin- cipal problem also included dual-domain mass-transfer, but was further extended for changing hydrochemical condi- tions in the column’s inflow water, which resulted in drastic changes in the U(VI) desorption pattern due to surface complexation reactions. For the three individual compo- nent problems, the corresponding simulation results agree very well among four well-known and thoroughly tested independent reactive transport codes, indicating that the proposed benchmark problem set is a suitable test case.
    Computational Geosciences 01/2015;
  • Nicolas C M Marthy, Olivier Bildstein, Philippe Blanc, Francis Claret, Benoit Cochepin, Eric C Gaucher, Diederik Jacques, Jean-Eric Lartigue, Sanheng Liu, K. Ulrich Mayer, Johannes C L Meeussen, Isabelle Munier, Ingmar Pointeau, Danyang Su, Carl Steefel
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    ABSTRACT: The use of the subsurface for CO2 storage, geo- thermal energy generation, and nuclear waste disposal will greatly increase the interaction between clay(stone) and concrete. The development of models describing the mineralogical transformations at this interface is complicated, because contrasting geochemical conditions (Eh, pH, solution composition, etc.) induce steep concentra- tion gradients and a high mineral reactivity. Due to the com- plexity of the problem, analytical solutions are not available to verify code accuracy, rendering code intercomparisons as the most efficient method for assessing code capabil- ities and for building confidence in the used model. A benchmark problem was established for tackling this issue. We summarize three scenarios with increasing geochemical complexity in this paper. The processes considered in the simulations are diffusion-controlled transport in saturated media under isothermal conditions, cation exchange reac- tions, and both local equilibrium and kinetically controlled mineral dissolution-precipitation reactions. No update of the pore diffusion coefficient as a function of porosity changes was considered. Seven international teams participated in this benchmarking exercise. The reactive transport codes used (TOUGHREACT, PHREEQC, with two different ways of handling transport, CRUNCH, HYTEC, ORCHESTRA, MIN3P-THCm) gave very similar patterns in terms of predicted solute concentrations and mineral distributions. Some differences linked to the considered activity models were observed, but they do not bias the general system evo- lution. The benchmarking exercise thus demonstrates that a reactive transport modelling specification for long-term performance assessment can be consistently addressed by multiple simulators.
    Computational Geosciences 01/2015;
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    ABSTRACT: A benchmark problem set consisting of four problem levels was developed for the simulation of Cr isotope fractionation in 1D and 2D domains. The benchmark is based on a recent field study where Cr(VI) reduction and accompanying Cr isotope fractionation occurs abiotically by an aqueous reaction with dissolved Fe2+ (Wanner et al., 2012., Appl. Geochem., 27, 644–662). The problem set includes simulation of the major processes affecting the Cr isotopic composition such as the dissolution of various Cr(VI) bearing minerals, fractionation during abiotic aqueous Cr(VI) reduction, and non-fractionating precipitation of Cr(III) as sparingly soluble Cr-hydroxide. Accuracy of the presented solutions was ensured by running the problems with four well-established reactive transport modeling codes: TOUGHREACT, MIN3P, CRUNCHFLOW, and FLOTRAN. Results were also compared with an analytical Rayleigh-type fractionation model. An additional constraint on the correctness of the results was obtained by comparing output from the problem levels simulating Cr isotope fractionation with the corresponding ones only simulating bulk concentrations. For all problem levels, model to model comparisons showed excellent agreement, suggesting that for the tested geochemical processes any code is capable of accurately simulating the fate of individual Cr isotopes.
    Computational Geosciences 01/2015;
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    ABSTRACT: We consider the Richards equation on a domain that is decomposed into nonoverlapping layers, i.e., the decomposition has no cross points. We assume that the saturation and permeability functions are space-independent on each subdomain. Kirchhoff transformation of each subdomain problem separately then leads to a set of semilinear equations, which can each be solved efficiently using monotone multigrid. The transformed subdomain problems are coupled by nonlinear continuity and flux conditions. This nonlinear coupled problem can be solved using substructuring methods like the Dirichlet–Neumann or Robin iteration. We give several numerical examples showing the discretization error, the solver robustness under variations of the soil parameters, and a hydrological example with four soil layers and surface water.
    Computational Geosciences 12/2014;
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    ABSTRACT: We discuss the construction of multi-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 approximations which preserve the conservative structure of the underlying control volume. Our main result is the generalization of multiscale control volume methods as multi-level inexact linear solvers for conservative discretizations through the design of a particular class of preconditioners. This construction thereby bridges the gap between multiscale approximation and linear solvers. The resulting approximation sequence is referred to as inexact solvers. We seek a conservative solution, in the sense of control-volume discretizations, within a prescribed accuracy. To this end, we give an abstract guaranteed a posteriori error bound relating the accuracy of the linear solver to the underlying discretization. These error bounds are explicitly computable for the grids considered herein. The afore-mentioned hierarchy of conservative approximations can also be considered in the context of multi-level upscaling, and this perspective is highlighted in the text as appropriate. The new construction is supported by numerical examples highlighting the performance of the inexact linear solver realized in both a multi- and two-level context for two- and three-dimensional heterogeneous problems defined on structured and unstructured grids. The numerical examples assess the performance of the approach both as an inexact solver, as well in comparison to standard algebraic multigrid methods.
    Computational Geosciences 12/2014;
  • Computational Geosciences 12/2014;
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    ABSTRACT: Changes of porosity, permeability, and tortuosity due to physical and geochemical processes are of vital importance for a variety of hydrogeological systems, including passive treatment facilities for contaminated groundwater, engineered barrier systems (EBS), and host rocks for high-level nuclear waste (HLW) repositories. Due to the nonlinear nature and chemical complexity of the problem, in most cases, it is impossible to verify reactive transport codes analytically, and code intercomparisons are the most suitable method to assess code capabilities and model performance. This paper summarizes model intercomparisons for six hypothetical scenarios with generally increasing geochemical or physical complexity using the reactive transport codes CrunchFlow, HP1, MIN3P, PFlotran, and TOUGHREACT. Benchmark problems include the enhancement of porosity and permeability through mineral dissolution, as well as near complete clogging due to localized mineral precipitation, leading to reduction of permeability and tortuosity. Processes considered in the benchmark simulations are advective-dispersive transport in saturated media, kinetically controlled mineral dissolution-precipitation, and aqueous complexation. Porosity changes are induced by mineral dissolution-precipitation reactions, and the Carman-Kozeny relationship is used to describe changes in permeability as a function of porosity. Archie’s law is used to update the tortuosity and the pore diffusion coefficient as a function of porosity. Results demonstrate that, generally, good agreement is reached amongst the computer models despite significant differences in model formulations. Some differences are observed, in particular for the more complex scenarios involving clogging; however, these differences do not affect the interpretation of system behavior and evolution.
    Computational Geosciences 11/2014;
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    ABSTRACT: Data assimilation in a reservoir with facies description using the ensemble Kalman filter (EnKF) is challenging. An important reason is that probability density functions for pixel-based representations of facies fields seldom follow the unimodal Gaussian assumption underlying traditional EnKF implementations. Different approaches for identification of facies fields, aiming to overcome this challenge, have been proposed within the EnKF framework. Level set (LS) representations of the facies field have been reported to alleviate the problems of multimodality. Several authors have, however, pointed out that the most commonly applied LS representation suffers from topological constraints that can create difficulties in an estimation setting. An alternative LS representation, that overcomes these topological constraints, leads to instabilities in the assimilated ensemble members. To overcome topological constraints, the recently proposed hierarchical LS representation is applied in an estimation setting for the first time in this paper. To improve stability and to alleviate challenges associated with model nonlinearities, we apply regularization by reduced representation of the LS functions and adjustable smoothing of the LS representation. The resolution of the reduced LS representation is selected based on the variability of the initial ensemble, aiming at preserving enough flexibility to disclose unexpected features. 2D and 3D estimation results demonstrate that the hierarchical LS representation does avoid topological constraints and that instabilities are avoided. The results suggest that the method is capable of handling estimation of facies fields while preserving geological plausibility.
    Computational Geosciences 10/2014; 18(5).
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    ABSTRACT: Geologic CO2 sequestration in deep saline aquifers is a promising technique to mitigate the effect of greenhouse gas emissions. Designing optimal CO2 injection strategy becomes a challenging problem in the presence of geological uncertainty. We propose a surrogate assisted optimisation technique for robust optimisation of CO2 injection strategies. The surrogate is built using Adaptive Sparse Grid Interpolation (ASGI) to accelerate the optimisation of CO2 injection rates. The surrogate model is adaptively built with different numbers of evaluation points (simulation runs) in different dimensions to allow automatic refinement in the dimension where added resolution is needed. This technique is referred to as dimensional adaptivity and provides a good balance between the accuracy of the surrogate model and the number of simulation runs to save computational costs. For a robust design, we propose a utility function which comprises the statistical moment of the objective function. Numerical testing of the proposed approach applied to benchmark functions and reservoir models shows the efficiency of the method for the robust optimisation of CO2 injection strategies under geological uncertainty.
    Computational Geosciences 10/2014; 18(5):763-778.
  • G. M. Coclite, S. Mishra, N. H. Risebro, F. Weber
    Computational Geosciences 10/2014; 18(5):637-659.
  • Computational Geosciences 09/2014;