1887

Abstract

Summary

Injection of seawater-like brines is one of the most successful EOR methods on the Norwegian Continental Shelf. Aqueous chemistry affects the mechanical strength of chalk. The injected seawater might trigger several mechanisms simultaneously and the importance of each mechanism is not fully understood. The aim of this study is to obtain an improved understanding of EOR mechanisms at pore scale by studying new mineral phases when flooding chalk with MgCl2 at reservoir conditions (130°C, 1 PV/day, 11.3 MPa effective stress). Two chalk cores were investigated, one artificial and one outcrop chalk. FE-SEM, STEM, and EDS-analyses show newly formed magnesite growing on calcite surfaces after 27 days. The Mg/Ca interphase is sharp, no diffusion of elements is observed on Ångström scale, and flooding experiments change the crystallography of phases. Whole-rock geochemistry of the Liége outcrop chalk flooded with MgCl2 for 3 years reveals a MgO content of c. 42 wt.%, but still c. 4 wt.% CaO. STEM mapping shows that CaO impurities are present in MgO dominated phases. These experiments confirm that magnesite grows as a new mineral phase even after short term flooding and that calcium is still present as impurities in the magnesite after long term flooding.

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/content/papers/10.3997/2214-4609.201700310
2017-04-24
2024-04-26
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References

  1. AustadT. and StandnesD. C.
    [2003] Spontaneous imbibition of water into oil-wet carbonates. Journal of Petroleum Science and Engineering, 39, 363–376.
    [Google Scholar]
  2. HeggheimT., MadlandM. V., RisnesR., and AustadT.
    [2005] A chemical induced enhanced weakening of chalk by seawater. Journal of Petroleum Science and Engineering, 46, 171–184.
    [Google Scholar]
  3. HiorthA., JettestuenE., LawrenceC. M., and MadlandM. 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]
  4. HjulerM. L. and FabriciusI. 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, 151–170.
    [Google Scholar]
  5. KorsnesR. I., StrandS., HoffØ., PedersenT., MadlandM. V., and AustadT.
    [2006] Does the chemical interaction between seawater and chalk affect the mechanical properties of chalk? In: CotthemA. V., CharlierR., ThimusJ. F., and TshibanguJ. P. (Eds.) Multiphysics Coupling and Long Term Behaviour in Rock Mechanics, Taylor & Francis, London, 427–434.
    [Google Scholar]
  6. KorsnesR. I., MadlandM. V., AustadT., HaverS., and RoslandG.
    [2008a] The effects of temperature on the water weakening of chalk by seawater. Journal of Petroleum Science and Engineering, 60, 183–193.
    [Google Scholar]
  7. KorsnesR. I., WerslandE., MadlandM. V., and AustadT.
    [2008b] Anisotropy in chalk studied by rock mechanics. Journal of Petroleum Science and Engineering, 62, 28–35.
    [Google Scholar]
  8. MadlandM. V., FinsnesA., AlkafadgiA., RisnesR., and AustadT.
    [2006] The influence of CO2 gas and carbonate water on the mechanical stability of chalk. Journal of Petroleum Science and Engineering, 51, 149–168.
    [Google Scholar]
  9. MadlandM. V., MidtgardenK., ManafovR., KorsnesR. I., KristiansenT., and HiorthA.
    [2008] The Effect of Temperature and Brine Composition on the Mechanical Strength of Kansas Chalk. International Symposium of the Society of Core Analysts, Abu Dhabi, 6.
    [Google Scholar]
  10. Madland, M., Hiorth, A., Omdal, E., Megawati, M., Hildebrand-Habel, T., Korsnes, R., 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.
    [Google Scholar]
  11. MindeM. W., MadlandM. V., ZimmermannU., and KorsnesR. I.
    [2016] Submicron investigations – What can we learn?. IOR Norway 2016, Stavanger.
    [Google Scholar]
  12. NermoenA., KorsnesR. I., HiorthA., and MadlandM. V.
    [2015] Porosity and permeability development in compacting chalks during flooding of nonequilibrium brines: Insights from long-term experiment: Journal of Geophysical Research: Solid Earth, 120, 2935–2960.
    [Google Scholar]
  13. StrandS., StandnesD. C., and AustadT.
    [2003] Spontaneous Imbibition of Aqueous Surfactant Solutions into Neutral to Oil-Wet Carbonate Cores: Effects of Brine Salinity and Composition: Energy & Fuels, 17, 1133–1144.
    [Google Scholar]
  14. WangW., MadlandM. V., ZimmermannU., NermoenA., KorsnesR. I., BertolinoS. R. A., and Hildebrand-HabelT.
    [2016] Evaluation of porosity change during chemo-mechanical compaction in flooding experiments on Liège outcrop chalk: Geological Society London Special Publications, 435.
    [Google Scholar]
  15. ZangiabadiB., KorsnesR. I., Hildebrand-HabelT., HiorthA., SurtarjanaI. K., LianA., and MadlandM. V.
    [2009] Chemical water weakening of various outcrop chalks at elevated temperature. In: LingH. I., SmythA., and BettiR., (Eds.) Poromechanics IV, DEStech Publications, Inc., Lancaster, 543–548.
    [Google Scholar]
  16. ZimmermannU., MadlandM. V., NermoenA., Hildebrand-HabelT., BertolinoS. A. R., HiorthA., KorsnesR. I., AudinotJ. N., and GrysanP.
    [2015] Evaluation of the compositional changes during flooding of reactive fluids using scanning electron microscopy, nano-secondary ion mass spectroscopy, x-ray diffraction, and whole-rock geochemistry: AAPG Bulletin, 99, 791–805.
    [Google Scholar]
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