Instantaneous rock transformations in the deep crust driven by reactive fluid flow

2020 ◽  
Author(s):  
Andreas Beinlich ◽  
Timm John ◽  
Johannes C. Vrijmoed ◽  
Masako Tominaga ◽  
Tomas Magna ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Carbon Sequestration ◽  
Reactive Transport ◽  
Subduction Zones ◽  
Large Scale ◽  
Transport Model ◽  
Plate Motion ◽  
Tectonic Deformation ◽  
Reaction Fronts ◽  
Reactive Fluids

<p>Fluid–rock interactions link mass and energy transfer with large-scale tectonic deformation, drive the formation of mineral deposits, carbon sequestration, and rheological changes of the lithosphere. While spatial evidence indicates that fluid–rock interactions operate on length scales ranging from the grain boundary to tectonic plates, the timescales of regional fluid–rock interactions remain essentially unconstrained, despite being critically important for quantifying the duration of fundamental geodynamic processes. Here we show that reaction-induced transiently high permeability significantly facilitates fast fluid flow through low-permeability rock of the mid-crust. Using observations from an exceptionally well-exposed fossil hydrothermal system to inform a multi-element advective–diffusive–reactive transport model, we show that fluid-driven reaction fronts propagate with ~10 cm year<sup>-1</sup><sub>,</sub> equivalent to the fastest tectonic plate motion and mid-ocean ridge spreading rates. Consequently, in the presence of reactive fluids, large-scale fluid-mediated rock transformations in continental collision and subduction zones occur on timescales of tens of years, implying that natural carbon sequestration, ore deposit formation, and transient and long-term petrophysical changes of the crust proceed, from a geological perspective, instantaneously.</p>

scholarly journals Mineralogical, numerical and analytical studies of the coupled oxidation of pyrite and coal

2003 ◽  
Vol 67 (2) ◽  
pp. 381-398 ◽  
Author(s):  
K. A. Evans ◽  
C. J. Gandy ◽  
S. A. Banwart
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Pyrite Oxidation ◽  
Spoil Heap ◽  
Reaction Fronts ◽  
Order Of Magnitude ◽  
Magnitude Variation ◽  
Discharge Chemistry ◽  
Analytical Expressions

Mineralogical, bulk and field leachate compositions are used to identify important processes governing the evolution of discharges from a coal spoil heap in County Durham. These processes are incorporated into a numerical one-dimensional advective-kinetic reactive transport model which reproduces field results, including gas compositions, to within an order of magnitude. Variation of input parameters allows the effects of incorrect initial assumptions on elemental profiles and discharge chemistry to be assessed. Analytical expressions for widths and speeds of kinetic reaction fronts are developed and used to predict long-term development of mineralogical distribution within the heap. Results are consistent with observations from the field site. Pyrite oxidation is expected to dominate O2 consumption in spoil heaps on the decadal timescale, although C oxidation may stabilize contaminants in effluents on the centennial scale.

Multicomponent multiphase reactive fluid flow in viscoelastoplastic porous media: localization patterns of fluid flow and strain

2021 ◽  
Author(s):  
Lyudmila Khakimova ◽  
Nikolai Belov ◽  
Artyom Myasnikov ◽  
Anatoly Vershinin ◽  
Kirill Krapivin ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Reactive Transport ◽  
Transport Model ◽  
Shear Bands ◽  
Porous Matrix ◽  
Deformation Localization ◽  
Linear Free Energy ◽  
Constrained Minimization Problem ◽  
Spectral Finite Elements ◽  
The Impact

<p>This work is devoted to developing the self-consistent thermo-hydro-chemo-mechanical reactive transport model to predict and describe natural and industrial petroleum processes at different scales.</p><p>We develop a version of the front tracking approach for multicomponent multiphase flow in order to treat spontaneous splitting of discontinuities. We revisit the solution for the Riemann problem and systematically classify all possible configurations as functions of initial concentrations on both sides of the discontinuity. We validate the algorithm against finite volume high-resolution technics and high-order spectral finite elements.</p><p>To calculate the parameters of phase equilibria, we utilize an approach based on the direct minimization of the Gibbs energy of a multicomponent mixture. This method ensures the consistency of the thermodynamic lookup tables. The core of the algorithm is the non-linear free-energy constrained minimization problem, formulated in the form of a linear programming problem by discretization in compositional space.</p><p>The impact of the complex rheological response of porous matrix on the morphology of fluid flow and shear deformation localization is considered. Channeling of porosity waves and shear bands morphology and their orientation is investigated for viscoelastoplastic both shear and bulk rheologies.</p>

scholarly journals <tt>POET</tt> (v0.1): Speedup of Many-Cores Parallel Reactive Transport Simulations with Fast DHT-Lookups

2021 ◽  
Author(s):  
Marco De Lucia ◽  
Michael Kühn ◽  
Alexander Lindemann ◽  
Max Lübke ◽  
Bettina Schnor
Keyword(s):  
Reactive Transport ◽  
Large Scale ◽  
Spent Nuclear Fuel ◽  
Co2 Storage ◽  
Hash Table ◽  
Distributed Hash Table ◽  
Reaction Fronts ◽  
Societal Challenges ◽  
Fuel Storage ◽  
Major Bottleneck

Abstract. Coupled reactive transport simulations are extremely demanding in terms of required computational power, which hampers their application and leads to coarsened and oversimplified domains. The chemical sub-process represents the major bottleneck: its acceleration is an urgent challenge which gathers increasing interdisciplinary interest along with pressing requirements for subsurface utilization such as spent nuclear fuel storage, geothermal energy and CO2 storage. In this context we 5 developed POET (POtsdam rEactive Transport), a research parallel reactive transport simulator integrating algorithmic improvements which decisively speedup coupled simulations. In particular, POET is designed with a master/worker architecture, which ensures computational efficiency on both multicore and cluster compute environments. POET does not rely on contiguous grid partitions for the parallelization of chemistry, but forms work packages composed of grid cells distant from each other. Such scattering prevents particularly expensive geochemical simulations, usually concentrated in the vicinity of a reactive front, from generating load imbalance between the available CPUs, as it is often the case with classical partitions. Furthermore, POET leverages an original implementation of Distributed Hash Table (DHT) mechanism to cache the results of geochemical simulations for further reuse in subsequent time-steps during the coupled simulation. The caching is hence particularly advantageous for initially chemically homogeneous simulations and for smooth reaction fronts. We tune the rounding employed in the DHT on a 2D benchmark to validate the caching approach, and we evaluate the performance gain of POET's master/worker architecture and the DHT speedup on a 3D benchmark comprising around 650 k grid elements. The runtime for 200 coupling iterations, corresponding to 960 simulation days, reduced from about 24 h on 11 workers to 29 minutes on 719 workers. Activating the DHT reduces the runtime further to 2 h and 8 minutes respectively. Only with this kind of reduced hardware requirements and computational costs it is possible to realistically perform the large scale, long-term complex reactive transport simulations, as well as performing the uncertainty analyses required by pressing societal challenges connected with subsurface utilization.

scholarly journals Redox hydrogeochemistry of organic rich floodplain exemplified by Ammer river

2019 ◽  
Vol 98 ◽  
pp. 09014
Author(s):  
Evgenii Kortunov ◽  
Chuanhe Lu ◽  
Richard Amos ◽  
Peter Grathwohl
Keyword(s):  
Organic Carbon ◽  
Reactive Transport ◽  
Large Scale ◽  
Transport Model ◽  
Water Quality Management ◽  
Nitrate Contamination ◽  
River Floodplain ◽  
Atmospheric Inputs ◽  
Sediment Layers ◽  
Floodplain Sediments

Diffusive groundwater pollution caused by agricultural and atmospheric inputs is a pressing issue in environmental management worldwide. Various researchers have studied nitrate contamination since the substantial increase of nitrogen fertilization in agriculture starting in the second half of the 20th century. This study addresses large scale reactive solute transport in typical landscapes and aquifers exemplified by geological analogues of southwestern Germany.. Fate of nitrate and other solutes (e.g. agricultural nitrate, ammonium, natural sulfate and dissolved organic carbon) was studied in a typical small river floodplain. Reactive transport model of Ammer river floodplain shows that agriculture nitrate is reduced rapidly in the Ammer floodplain sediments. However, there is a potential for geogenic production of ammonium in sediment layers high in organic carbon and peat, which might be a major source of nitrate in the drains. Part of the nitrate in drains and creeks in the Ammer valley thus could be of geogenic origin. Such findings are relevant for regional land and water quality management.

scholarly journals Large‐Scale Experiments in Microbially Induced Calcite Precipitation (MICP): Reactive Transport Model Development and Prediction

2018 ◽  
Vol 54 (1) ◽  
pp. 480-500 ◽  
Author(s):  
Mohamed K. Nassar ◽  
Deviyani Gurung ◽  
Mehrdad Bastani ◽  
Timothy R. Ginn ◽  
Babak Shafei ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Large Scale ◽  
Transport Model ◽  
Model Development ◽  
Calcite Precipitation ◽  
Microbially Induced Calcite Precipitation ◽  
Reactive Transport Model

Inhomogeneous rock compositions and varying dissolution rates affect evolution and shape of leaching zones in potash seams

2021 ◽  
Author(s):  
Svenja Steding ◽  
Thomas Kempka ◽  
Axel Zirkler ◽  
Michael Kühn
Keyword(s):  
Fluid Flow ◽  
Reactive Transport ◽  
Transport Model ◽  
Chemical Species ◽  
Simulation Environment ◽  
Dissolution Rates ◽  
Reactive Transport Model ◽  
Hazard Potential ◽  
Transport Simulation ◽  
Salt Deposits

&lt;p&gt;Salt deposits host an important industrial raw material and provide storage capacities for energy and nuclear waste. However, leaching zones can seriously endanger the development and utilisation of salt deposits for these purposes, especially if these occur in potash seams. Their increased solubility enables even NaCl-saturated solutions, if present, to deeply penetrate these seams. The resulting salt dissolution processes generate fluid flow paths and affect the mechanical rock integrity. To model the timely evolution of leaching zones and to assess their hazard potential, a reactive transport model has been developed, taking into account not only the complex dissolution and precipitation behaviour of potash salts, but also the resulting porosity and permeability changes as well as density-driven chemical species transport. Additionally, the model makes use of an approach to describe transport and chemical reactions at the interface between impermeable (dry) salt rocks and permeated leaching zones (Steding et al., 2021). In the present study, we focus on the effect of heterogeneity of the mineral distribution within potash seams and on the influence of mineral- and saturation-dependent dissolution rates.&lt;/p&gt;&lt;p&gt;The applied reactive transport model is based on a coupling of the geochemical module PHREEQC (Parkhurst &amp; Appelo, 2013) with the TRANSport Simulation Environment (Kempka, 2020) as well as the newly developed extension of an interchange approach (Steding et al., 2021). A numerical model has been developed and applied to simulate the leaching process of a carnallite-bearing potash seam due to natural density-driven convection. The results show that both, the mineral composition and dissolution rate of the original salt rock, strongly influence the shape and evolution of the leaching zone (Steding et al., 2021).&lt;/p&gt;&lt;p&gt;In nature, strong variations of the mineralogy occur within potash seams with random or stratified distributions. Furthermore, dissolution rates depend on the mineral itself as well as on its saturation state. Both may considerably influence the growth rate of a leaching zone. Therefore, the reactive transport model has been extended by mineral- and saturation-dependent dissolution rates. A scenario analysis has been undertaken to compare the impact of homogeneous and heterogeneous rock compositions. For that purpose, the carnallite content in the potash seam was varied from 5 to 25&amp;#160;wt.&amp;#160;% including different stratifications and random distributions. The simulations were classified by means of the P&amp;#233;clet and Damk&amp;#246;hler numbers, and the long-term behaviour as well as hazard potential are discussed.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Parkhurst, D.L.; Appelo, C.A.J. (2013). Description of Input and Examples for PHREEQC Version 3 - a Computer Program for Speciation, Batch-reaction, One-dimensional Transport, and Inverse Geochemical Calculations. In Techniques and Methods; Publisher: U.S. Geological Survey; Book 6, 497 pp&lt;/p&gt;&lt;p&gt;Kempka, T. (2020). Verification of a Python-based TRANsport Simulation Environment for density-driven fluid flow and coupled transport of heat and chemical species. Adv. Geosci. 54, 67&amp;#8211;77. &lt;/p&gt;&lt;p&gt;Steding, S.; Kempka, T.; Zirkler, A.; K&amp;#252;hn, M. (2021). Spatial and temporal evolution of leaching zones within potash seams reproduced by reactive transport simulations. Water 13, 168. &lt;/p&gt;

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