To understand the alterations in geomechanical and mineralogical properties of reservoir chalk injected with seawater, countless experiments have been carried out through decades of research at UiS. Several parameters are varied to understand how these parameters impact fluid-flow, rock-fluid interaction and compaction, which is an important drive mechanism for Enhanced Oil Recovery (EOR). Identification of mineralogical alterations is crucial input to modelling and simulation of EOR methods.

We present the results from flow through experiments on Liège chalk from three ultra-long-term tests. The core were flooded with MgCl2 at reservoir temperature (130°C) and hydrostatic stresses above yield (9.5, 10.4 and 12.6 MPa), with one core was flooded for a short period with a mixture of MgCl2 and CaCl2, and with MgCl2 brines at different pH, ~2.7, ~5.7 and ~9.

The studies based on Mineral Liberation Analyzer and Transmission Electron Microscopy show two fronts moving through the cores at different velocities. The first alterations are partial dissolution of calcite with precipitation of secondary minerals like high-magnesium carbonate and clays, followed by fronts of complete transformation to the Mg-rich mineral. Random calcium impurities (<4wt%) are present in all analysed magnesite crystals. In addition, precipitation of Si-Mg-bearing clays is observed throughout all flooded cores.


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  1. Andersson, M. P., Dideriksen, K., Sakuma, H., and Stipp, S. L. S.
    [2016]. Modelling how incorporation of divalent cations affects calcite wettability–implications for biomineralisation and oil recovery. Scientific Reports, 6 doi:10.1038/srep28854
    https://doi.org/10.1038/srep28854 [Google Scholar]
  2. Fandrich, R., Gu, Y., Burrows, D., and Moeller, K.
    [2007]. Modern SEM-based mineral liberation analysis. International Journal of Mineral Processing, 84(1), 310–320. doi:10.1016/j.minpro.2006.07.018
    https://doi.org/10.1016/j.minpro.2006.07.018 [Google Scholar]
  3. Heggheim, T., Madland, M. V., Risnes, R., and Austad, T.
    [2005]. A chemical induced enhanced weakening of chalk by seawater. Journal of Petroleum Science and Engineering, 46, 171–184.
    [Google Scholar]
  4. Hiorth, A., Cathles, L. M., and Madland, M. V.
    [2010]. The Impact of Pore Water Chemistry on Carbonate Surface Charge and Oil Wettability. The Impact of Pore Water Chemistry on Carbonate Surface Charge and Oil Wettability, 85(1), 1–21.
    [Google Scholar]
  5. Hiorth, A., Jettestuen, E., Cathles, L. M., and Madland, M. V.
    [2013]. Precipitation, dissolution, and ion exchange processes coupled with a lattice Boltzmann advection diffusion solver. Geochimica Et Cosmochimica Acta, 104, 99–110.
    [Google Scholar]
  6. Hjuler, M. L., and Fabricius, I. L.
    [2009]. Engineering properties of chalk related to diagenetic variations of Upper Cretaceous onshore and offshore chalk in the North Sea area. Journal of Petroleum Science and Engineering, 68(3), 151–170. doi:10.1016/j.petrol.2009.06.005
    https://doi.org/10.1016/j.petrol.2009.06.005 [Google Scholar]
  7. Korsnes, R. I., Madland, M. V., Austad, T., Haver, S., and Rosland, G.
    [2008]. The effects of temperature on the water weakening of chalk by seawater. Journal of Petroleum Science and Engineering, 60(3), 183–193. doi:10.1016/j.petrol.2007.06.001
    https://doi.org/10.1016/j.petrol.2007.06.001 [Google Scholar]
  8. Madland, M., Hiorth, A., Omdal, E., Megawati, M., Hildebrand-Habel, T., Korsnes, R., Evje, S., and Cathles, L.
    [2011]. Chemical Alterations Induced by Rock–Fluid Interactions When Injecting Brines in High Porosity Chalks. Transport in Porous Media, 87(3), 679–702. doi:10.1007/s11242‑010‑9708‑3
    https://doi.org/10.1007/s11242-010-9708-3 [Google Scholar]
  9. Madland, M. V., Finsnes, A., Alkafadgi, A., Risnes, R., and Austad, T.
    [2006]. The influence of CO2 gas and carbonate water on the mechanical stability of chalk. Journal of Petroleum Science and Engineering, 51(3–4), 149–168. doi:http://dx.doi.org/10.1016/j.petrol.2006.01.002
    [Google Scholar]
  10. Madland, M. V., Korsnes, R. I., Hiorth, A., Midtgarden, K., Manafov, R., and Kristiansen, T. G.
    [2008]. THE EFFECT OF TEMPERATURE AND BRINE COMPOSITION ON THE MECHANICAL STRENGTH OF KANSAS CHALK. In: International Symposium of the Society of Core Analysts, Abu Dhabi.
    [Google Scholar]
  11. Maury, V., Piau, J. M., and Halle, G.
    (1996). Subsidence induced by water injection in water sensitive reservoir rocks: The example of Ekofisk. In: SPE European Petroleum Conference, Milan, Italy153–170.
    [Google Scholar]
  12. Megawati, M., Hiorth, A., and Madland, M. V.
    [2012]. The Impact of Surface Charge on the Mechanical Behavior of High-Porosity Chalk. Rock Mechanics and Rock Engineering, 1–18.
    [Google Scholar]
  13. Megawati, M., Madland, M. V., and Hiorth, A.
    [2015]. Mechanical and physical behavior of high-porosity chalks exposed to chemical perturbation. Journal of Petroleum Science and Engineering, 133, 313–327.
    [Google Scholar]
  14. Molenaar, N., and Zijlstra, J. J. P.
    [1997]. Differential early diagenetic low-Mg calcite cementation and rhythmic hardground development in Campanian-Maastrichtian chalk. Sedimentary Geology, 109(3), 261–281. doi:10.1016/s0037‑0738(96)00064‑4
    https://doi.org/10.1016/s0037-0738(96)00064-4 [Google Scholar]
  15. Nagel, N. B.
    [1998]. Ekofisk Field Overburden Modelling. In: SPE/ISRM Eurock ‘98, Trondheim, Norway.
    [Google Scholar]
  16. Nermoen, A., Korsnes, R. I., Hiorth, A., and Madland, M. V.
    [2015]. Porosity and permeability development in compacting chalks during flooding of non-equlibrium brines - insights from a long term experiment. Journal of Geophysical Research: Solid Earth, 120.
    [Google Scholar]
  17. Risnes, M. V., Madland, M. V., Hole, M. V., and Kwabiah, M. V.
    [2005]. Water weakening of chalk -Mechanical effects of water-glycol mixtures. Journal of Petroleum Science and Engineering, 48(1–2), 21–36. doi:10.1016/j.petrol.2005.04.004
    https://doi.org/10.1016/j.petrol.2005.04.004 [Google Scholar]
  18. Risnes, R., Haghighi, H., Korsnes, R. I., and Natvik, O.
    [2003]. Chalk - Fluid interactions with glycol and brines. Tectonophysics, 370, 213 – 226.
    [Google Scholar]
  19. Sakuma, H., Andersson, M. P., Bechgaard, K., Stipp, S. L. S., and Sakuma, S. L. S.
    [2014]. Surface tension alteration on calcite, induced by ion substitution. Journal of Physical Chemistry C, 118(6), 3078–3087. doi:10.1021/jp411151u
    https://doi.org/:10.1021/jp411151u [Google Scholar]
  20. Teufel, L. W., Rhett, D. W., and Farrell, H. E.
    Effect of Reservoir Depletion And Pore Pressure Drawdown On In Situ Stress And Deformation In the Ekofisk Field, North Sea. In.
    [Google Scholar]
  21. Wang, W., Madland, M. V., Zimmermann, U., Nermoen, A., Korsnes, R. I., Bertolino, S. R. A., and Hildebrand-Habel, T.
    [2016]. Evaluation of porosity change during chemo-mechanical compaction in flooding experiments on Liège outcrop chalk. Geological Society, London, Special Publications, 435. doi:10.1144/sp435.10
    https://doi.org/10.1144/sp435.10 [Google Scholar]
  22. Wang, W., Zimmermann, U., Madland, M. V., Andersen, P. Ø., Korsnes, R. I., Minde, M., Bertolino, S. R. A., Schulz, B., and Haser, S.
    [subm.]. Comparative Study of Five Outcrop Chalks Flooded at Reservoir Conditions: Chemo-Mechanical Behaviour and Profiles of Compositional Alteration.
    [Google Scholar]
  23. Zhang, P., Tweheyo, M. T., and Austad, T.
    [2007]. Wettability alteration and improved oil recovery by spontaneous imbibition of seawater into chalk: Impact of the potential determining ions Ca 2+, Mg 2+, and SO 4 2−. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 301(1), 199–208. doi:10.1016/j.colsurfa.2006.12.058
    https://doi.org/10.1016/j.colsurfa.2006.12.058 [Google Scholar]
  24. Zimmermann, U., Madland, M. V., Nermoen, A., Hildebrand-Habel, T., Bertolino, S. A. R., Hiorth, A., Korsnes, R. I., Audinot, J.-N., and Grysan , P.
    [2015]. Evaluation of the compositional changes during flooding of reactive fluids using scanning electron microscopy, nano-secondary ion mass spectrometry, x-ray diffraction, and whole-rock geochemistry. AAPG Bulletin, 99(5), 791 – 805.
    [Google Scholar]

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