MRST - MATLAB Reservoir Simulation Toolbox

Numerical CO2 laboratory
MRST-co2lab is an open-source software for studying long-term storage of CO2 in large-scale saline aquifers. MRST-co2lab is implemented as a add-on module to the MATLAB Reservoir Simulation Toolbox (MRST) and  consists of simulators and workflow tools, as well as a large number of library functions, tutorial-type examples, and interfaces to public data sets. The  purpose of MRST-co2lab is to provide reliable modeling of real storage operations, enable interactive experimentation with public data sets, and establish a framework that simplifies the research, development and implementation of  new models and computational methods.

When CO2 is injected into a subsurface rock formation, it forms a separate free, supercritical phase which is commonly referred to as the CO2 plume. The CO2 phase is less dense than the formation water and will therefore start to rise upwards. CO2 is typically injected under a sealing rock, in which the capillary pressure inside pore throats is greater than the bouyancy pressure of the CO2. The seal will form a top surface on the permeable rock and prevent a direct upward movement of CO2. If the top seal is sloping, the CO2 will form a thin layer underneath that slowly migrates in the upslope direction.

In general there are four basic mechanisms that will prevent the CO2 from leaking back to the atmosphere:

  • Structural/stratigraphical trapping - as the CO2 plume migrates upward, it will start to accumulate inside small bumps in the top surface until it spills over and continues upwards. Once inside a trap, the CO2 will remain trapped unless the height of the plume creates a capillary presure that enables the CO2 to enter the seal.
  • Residual trapping - when the concentration of CO2 at the tail of the migrating plume falls below a certain level, CO2 becomes trapped by capillary pressure from the water in void space between rock grains and stops migrating.
  • Solubility trapping - the injected CO2 will dissolve in water. This increases the density of the water, which starts to sink downwards, thereby enabling a mixing process that will enable the CO2 to become more dispersed in the resident brine over time
  • Mineral trapping - the dissolved CO2 will react with the reservoir rock to form and precipitate carbonate minerals.

Modeling capabilities

MRST-co2lab focuses on the three trapping mechanisms: structural, residual, and solubility trapping.  To this end, the module offers the following capabilities:

For those seeking a more conventional simulation approach, CO2 sequestration can be simulated using MRST's standard reservoir simulation capabilities on structured and unstructured grid:

We also have several examples of compositional flow capabilities inhouse (these may be available upon request).

The development of the Numerical CO2 Laboratory is funded by CLIMIT,  the Norwegian research programme for accelerating the commercialisation of Carbon Capture and Storage (CCS).

Intended use

MRST-co2lab can be used for several purposes:

  • As a teaching tool:
    • interactive examples to develop students’ physical intuition
    • visual examples to demonstrate the interplay between different physical processes
  • Model studies:
    • study different trapping mechanisms (structural, residual, dissolution)
    • validation of different injection scenarios
    • provide rough risk estimates
    • provide benchmark cases and simplify use of data sets that are publicly available
  • Development of new methodologies:
    • provide a framework for fast prototyping of new models and methods
    • simplify comparison of different models and methods

Literature

Read more about structural trapping, spill-point analysis, vertical-equilibrium models, and their applications in the following papers:

  1. H. M. Nilsen, K.-A. Lie, O. Møyner, and O. Andersen. Spill-point analysis and structural trapping capacity in saline aquifers using MRST-co2lab. Computers & Geosciences, Vol. 75, pp. 33-43, 2015. DOI: 10.1016/j.cageo.2014.11.002.
  2. H. M. Nilsen, K.-A. Lie, and O. Andersen. Robust simulation of sharp-interface models for fast estimation of CO2 trapping capacity. Computational Geosciences, 2015. DOI: 10.1007/s10596-015-9549-9
  3. H. M. Nilsen, K.-A. Lie, and O. Andersen. Fully-implicit simulation of vertical-equilibrium models with hysteresis and capillary fringe. Computational Geosciences, 2015. DOI: 10.1007/s10596-015-9547-y
  4. H. M. Nilsen, K.-A. Lie, and O. Andersen. Analysis of CO2 trapping capacities and long-term migration for geological formations in the Norwegian North Sea using MRST-co2lab. Computers & Geosciences, Vol. 79, pp. 15-26, 2015. DOI: 10.1016/j.cageo.2015.03.001
  5. K.-A. Lie, H. M. Nilsen, O. Andersen, and O. Møyner. A simulation workflow for large-scale CO2 storage in the Norwegian North Sea. ECMOR XIV, Catania, Sicily, Italy, 8-11 September 2014. DOI: 10.3997/2214-4609.20141877
  6. O. Andersen, H. M. Nilsen, and K.-A. Lie. Reexamining CO2 storage capacity and utilization of the Utsira Formation. ECMOR XIV, Catania, Sicily, Italy, 8-11 September 2014. DOI: 10.3997/2214-4609.20141877
  7. H. M Nilsen, P. A. Hererra, M. Ashraf, I. Ligaarden, M. Iding, C. Hermanrud K.-A. Lie, J. M. Nordbotten, H. K. Dahle, and E. Keilegavlen, Field-case simulation of CO2 -plume migration using vertical-equilibrium models. Energy Procedia 2011, DOI: 10.1016/j.egypro.2011.02.315.
  8. I. S. Ligaarden, and H. M. Nilsen. Numerical aspects of using vertical equilibrium models for simulating CO2 sequestration. Proceedings of ECMOR XII, Oxford, UK, 6-9 September 2010. DOI: 10.3997/2214-4609.20144940
  9. H. M. Nilsen, A. R. Syversveen, K.-A. Lie, J. Tveranger, and J. M. Nordbotten. Impact of top-surface morphology on CO2 storage capacity. Int. J. Greenhouse Gas Control, Vol. 11, pp. 221-235, 2012. DOI: 10.1016/j.ijggc.2012.08.012
  10. K.-A. Lie, H. M. Nilsen, O. Andersen, O. Møyner.  A simulation workflow for large-scale CO2 storage in the Norwegian North Sea.  Computational Geosciences. 2015. DOI: 10.1007/s10596-015-9487-6
  11. S.E. Gasda, H.M. Nilsen, H.K. Dahle. Impact of structural heterogeneity on upscaled models for large-scale CO2 migration and trapping in saline aquifers Adv. Water Resour. 2013, vol. 62 part C, pp 520-532.  DOI: 10.1016/j.advwatres.2013.05.003
  12. O. Andersen, H. M. Nilsen, K.-A. Lie. An open-source toolchain for simulation and optimization of aquifer-wide CO2 storage.  Energy Procedia, (accepted)
  

 

Illustration of the chain of tools implemented in MRST-co2lab: from identification of structural traps, via spill-paths from injection point, to vertical-equilbrium simulations accounting for the combined long-term, large-scale effects of structural, residual, and solubility trapping.

 

Optimized injection plan for large-scale storage in the Utsira Formation. Color shows CO2 content, red lines outline the plume, whereas structural traps are shown in purple.

 

Two of the developers, Halvor Møll Nilsen and Olav Møyner, demonstrating the interactive viewer for identifying structural traps and performing vertical-equilibrium simulations.

 

 

Download

Since 2014a, MRST-co2lab comes bundled with the standard MRST release. 

Published November 16, 2009