Applied Geosciences - Geohydromodelling

Completed projects

CO2-MoPa

Modelling and parameterisation of CO2 storage in deep saliniferous formations for dimension and risk analyses

For the acceptance of new technologies, such as the storage of CO2 in deep geological formations (CCS), a well-founded risk assessment and risk analysis is essential. Required are therefore monitoring strategies and policies during and after an injection for both regular operation as well as the detection of a possible leakage. Testing and evaluating these strategies is difficult at existing sites, due to a lack of understanding of the system parameters, especially the spatially distributed geologic parameters, and the actual processes taking place. Testing of the required methods however can be carried out using synthetic numerical modeling studies, as in these cases the parameters and the processes involved are known exactly.

The modeling and numerical simulation of injection and propagation of CO2 in geological formations will play a crucial role for the understanding of the physico-chemical processes acting on different time and length scales as well as for the evaluation of efficiency and safety of the site considered. To perform these simulations, both the appropriate simulation programs as well as the appropriate parameters are necessary. Within the project, therefore the parameters and numerical simulation of the coupled thermo-hydro-mechanical-chemical processes in the reservoir has been considered. The spatial parameterization of geological structures was investigated exemplarily for Schleswig-Holstein. For parameterization, comprehensive data and literature evaluations were performed for all the necessary parameters, particularly examining conditions for consistent geochemical parameterizations. Based on experiments carried out in the project, geomechanical processes and kinetic mineral dissolution were quantified experimentally. For the numerical simulation of CO2 storage, a numerical modeling system was developed that represents the governing processes involved. The respective process couplings were implemented and their impact quantified. The effects of a CO2 storage operation were evaluated both by hydraulic monitoring methods as well as a geophysical monitoring using synthetic seismic, geoelectric and gravity measurements. Using a virtual site scenario, the entire work flow of geological and geometrical parameterization, process parameterization and numerical process simulations with subsequent evaluation of the effects induced as well as of strategies for their monitoring was performed and its applicability demonstrated.

Project partners:

  • Institute for Geosciences, Kiel University
  • Helmholtz Centre for Environmental Research GmbH – UFZ
  • Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart
  • Geological Survey Schleswig-Holstein, State Agency for Agriculture, Environment and Rural Areas
     

Project duration:

April 2008 - March 2011
 

Funding:

This study was funded by the German Federal Ministry of Education and Research (BMBF), EnBW Energie Baden-Württemberg AG, E.ON Energie AG, E.ON Gas Storage AG, RWE Dea AG, Vattenfall Europe Technology Research GmbH, Wintershall Holding AG and Stadtwerke Kiel AG as part of the CO2-MoPa joint project in the framework of the Special Program GEOTECHNOLOGIEN.

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CLEAN

Coupled THMC processes in the reservoir near field: Geochemical simulation of CO2 injection

The injection of CO2 in a depleted gas reservoir results in geochemical reactions between the formation brine and the rock matrix. Dissolution or precipitation of mineral phases will result in changes of porosity and permeability of the reservoir, which may cause feedbacks on the flow- and transport processes. A reliable characterisation and assessment of the relevant storage mechanisms has to take into account the time dependency of such reactions and feedback processes.

Therefore, in this project the THMC simulator OpenGeoSys (OGS) was extended for the kinetic limitation of CO2-fluid-mineral reactions. For this end, a generalized but very flexible Lasaga-type rate law was implemented in OGS. Moreover, the already existing interface of OGS to the geochemical code ChemApp was extended to allow for the exchange of consistent thermodynamic data between the OGS kinetics module and ChemApp. The verification of the coupled simulator was achieved by benchmark comparisons against analytical solutions and code comparison against other models. The successfully verified simulator then was applied for a site specific investigation of mineral trapping of CO2 and the consequential changes of porosities due to an injection of CO2 into the Altmark gas field for enhanced gas recovery. The scenario simulations show that the mineral trapping of CO2 may require very long times and geochemical equilibrium is reached only beyond 10000 years after the injection. Changes in porosity predicted by the scenario simulations with about -1 % are rather small, which is due to the limited extent of mineral conversion reactions and the small amounts of CO2 trapped in mineral form.

 

Project partners:

  • GFZ Potsdam
  • BGR Hannover
  • DBI gGmbH Freiberg
  • DMT GmbH Essen
  • FU Berlin GDF
  • SUEZ E&P GmbH
  • GICON GmbH Dresden
  • IFINKOR gGmbH Iserlohn
  • TU Clausthal
  • TU Dresden
  • UFZ Leipzig
  • Universität Erlangen-Nürnberg
  • Universität Halle-Wittenberg
  • Universität Jena
  • Universität Kiel
  • Universität Tübingen

 

Project duration:

July 2008 - June 2011
 

Funding:

This study was funded by the German Federal Ministry of Education and Research (BMBF), as part of the CLEAN project in the framework of the Special Program GEOTECHNOLOGIEN.

 

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DECOVALEX-2015

DEvelopment of COupled models and their VALidation against EXperiments

 The DECOVALEX project is an international research and model comparison collaboration. Aim of the project is to advance the understanding and modeling of coupled thermo-hydro-mechanical (THM) and thermo-hydro-mechanical-chemical (THMC) processes in geological systems. Prediction of these coupled effects is an essential part of the performance and safety assessment of geologic disposal systems for radioactive waste and spent nuclear fuel (http://www.decovalex.org).

DECOVALEX -2015 is the current and 6th project phase of the collaboration of regulatory authorities and nuclear waste management organizations initiated in 1992. In Task B1, Kiel University and the Swiss Federal Nuclear Safety Inspectorate ENSI collaborate in the development of numerical models to reproduce the laboratory experiments performed in the Task B1 and deepen the understanding of the THM processes that take place in the buffer material and surrounding host rock where the radioactive material might be stored.

DECOVALEX Figure

Figure: Virtual 3D-view of the DECOVALEX HE-E experiment on the effects of heating on bentonite and the surrounding host rock (Source: http://www.decovalex.org/tast-b1.html).

Funding partners:

  • BGR: Federal Institute for Geosciences and Natural Resources, Germany
  • CAS: Chinese Academy of Sciences
  • DOE: Department of Energy, USA
  • ENSI: Swiss Federal Nuclear Safety Inspectorate, Switzerland
  • IRSN: Institut de Radioprotection et de Sûreté Nucléaire, France
  • JAEA: Japan Atomic Energy Agency, Japan
  • KAERI: Korean Atomic Energy Research Institute, Republic of Korea
  • NDA: Nuclear Decommissioning Authority, UK
  • NRC: Nuclear Regulatory Commission, USA
  • RAWRA: Radioactive Waste Repository Authority, Czech Republic
  • UFZ: Helmholtz Centre for Environmental Research, Germany

 

Project duration:

2012 - 2015

Project website:

http://www.decovalex.org/index.html

Final report:

DECOVALEX-2015: Kiel University's final report

 

Reactions in Porous Media

The main aim of the DFG research group "Reactions in Porous Media" is the investigation and analysis of mass transfer limited reactive processes in groundwater at different spatial and temporal scales, such as dissolution of non-aqueous phase liquids (NAPL) across the water-NAPL interface, or microbially mediated degradation of organic contaminant plumes limited by transverse mixing of reaction partners at the plume fringe.

One of the major foci of the CAU Kiel subproject was the numerical evaluation of flow-through tank experiments of conservative and reactive tracer transport in artificial lab-scale sand aquifers aimed at the determination of transverse dispersivities. High-resolution numerical simulations of synthetic tank experiments, where all parameters (porosity, hydraulic conductivity, longitudinal and transverse dispersivities, etc.) are known a priori, were performed with the the OpenGeoSys code (OGS) to assess commonly used parameter estimation approaches. Sensitivity analyses with the numerical model were used to improve the experimental set-up of laboratory tank experiments subsequently performed in collaboration with the Center of Applied Geosciences (University of Tübingen), where conservative tracer transport was studied in homogeneous and heterogeneous porous media and at different flow velocities in order to analyze the tracer mixing behavior.

The second focus of the CAU Kiel subproject was the model based evaluation and interpretation of reactive transport experiments on aromatic hydrocarbon degradation performed at the German Research Center for Environmental Health, Helmholtz Zentrum München. For this purpose, the OGS code was extended by implementation of isotope fractionation as a new reaction process and the MPI-parallelization of the OGS-reaction kernel in order to increase the computational efficiency of the code. Numerical modelling were used as a tool to evaluate a 75 day experiment of transverse dispersion limited aerobic / anaerobic toluene and deuterium labelled ethylbenzene degradation by competitive aerobic and anaerobic (denitrifying) bacterial strains. Reproduction of measured toluene and ethylbenzene concentrations as well as isotope fractionation patterns with the numerical model allowed insight in the spatio-temporal distribution of aerobic and anaerobic biodegradation activity and kinetics of the two competing bacterial strains.

 

Project partners:

  • Kiel University
  • University of Tübingen
  • Helmholtz Centre Munich

Project duration:

July2008 – June 2011

Funding:

This work is a cooperation within the research group ‘‘Reactions in Porous Media’’ (FOR 525/2) funded by the Deutsche Forschungsgemeinschaft.

Project website:

http://gepris.dfg.de/gepris/projekt/5470602

 

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