1887

Abstract

Summary

Laboratory studies designed to measure the strength of rocks from a geothermal reservoir, to assist geothermal reservoir prospection, stimulation, and optimisation strategies, often perform experiments on dry or water-saturated samples. Since these rocks in-situ are saturated with hydrothermal brine, we performed laboratory strength experiments to explore the influence of brine on the short-term strength of sandstones (from the Buntsandstein, a lithostratigraphic unit common to many geothermal sites in the Upper Rhine Graben) from the EPS-1 exploration well at the Soultz-sous-Forêts geothermal site (France). Our experiments show that, although the water- and brine-saturated sandstones were weaker than their dry counterparts, there was essentially no difference between the strength of the sandstones saturated in water and brine. We consider the reduction in strength in the presence of water or brine as the result of a decrease in specific surface free energy. A decrease in the short-term strength of reservoir sandstones in the presence of hydrothermal brines likely require brines with higher salinities and/or lower values of pH than those typically found within the Upper Rhine Graben (salinity of ~10% and a pH of 5.5).

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201901265
2019-06-03
2024-04-26
Loading full text...

Full text loading...

References

  1. Aichholzer, C., Duringer, P., Orciani, S. and Genter, A
    . [2016] New stratigraphic interpretation of the Soultz-sous-Forêts 30-year-old geothermal wells calibrated on the recent one from Rittershoffen(Upper Rhine Graben, France). Geotherm. Energy4:13.
    [Google Scholar]
  2. Baud, P., Zhu, W. and Wong, T.-f
    . [2000] Failure mode and weakening effect of water on sandstone. J. Geophys. Res. 105(B7), 16371–16389.
    [Google Scholar]
  3. Genter, A. and TraineauH.
    [1996] Analysis of macroscopic fractures in granite in the HDR geothermal well EPS-1, Soultz-sous-Forêts, France. J. Volcanol. Geotherm. Res., 72, 121–141.
    [Google Scholar]
  4. Heap, M.J., Kushnir, A.R.L., Gilg, H.A., Wadsworth, F.B., Reuschlé, T. and Baud, P
    . [2017] Microstructural and petrophysical properties of the Permo-Triassic sandstones (Buntsandstein) from the Soultz-sous-Forêts geothermal site (France). Geotherm. Energy5(1):26.
    [Google Scholar]
  5. Heap, M.J., Reuschlé, T., Kushnir, A.R.L. and Baud, P
    . [2018] The influence of hydrothermal brine on the short-term strength and elastic modulus of sandstones from exploration well EPS-1 at Soultz-sous-Forêts (France). Geotherm. Energy, 6(1):29.
    [Google Scholar]
  6. Heap, M.J., Villeneuve, M., Kushnir, A.R.L., Farquharson, J.I., Baud, P. and Reuschlé, T
    . [2019] Rock mass strength and elastic modulus of the Buntsandstein: an important lithostratigraphic unit for geothermal exploitation in the Upper Rhine Graben. Geothermics, 77, 236–256.
    [Google Scholar]
  7. Hoek, E., Carranza-Torres, C. and Corkum, B
    . [2002]. Hoek-Brown failure criterion-2002 edition. Proceedings of NARMS-Tac, 1, 267–273.
    [Google Scholar]
  8. Kushnir, A.R.L., Heap, M.J., Baud, P., Gilg, H.A., Reuschlé, T., Lerouge, C., Dezayes, C. and Duringer, P
    . [2018] Characterizing the physical properties of rocks from the Paleozoic to Permo-Triassic transition in the Upper Rhine Graben. Geotherm. Energy, 6:16.
    [Google Scholar]
  9. Parks, G.A
    . [1984] Surface and interfacial free energies of quartz. J. Geophys. Res., 89(B6), 3997–4008.
    [Google Scholar]
  10. Sanjuan, B., Millot, R., Dezayes, C. and Brach, M
    . [2010] Main characteristics of the deep geothermal brine (5 km) at Soultz-sous-Forêts (France) determined using geochemical and tracer test data. Comptes Rendus Geoscience, 342, 546–559.
    [Google Scholar]
  11. Shukla, R., Ranjith, P.G., Choi, S.K., Haque, A., Yellishetty, M. and Hong, L.
    [2013] Mechanical behaviour of reservoir rock under brine saturation. Rock Mech. Rock Eng., 46, 83–93.
    [Google Scholar]
  12. Vidal, J. and Genter, A
    . [2018] Overview of naturally permeable fractured reservoirs in the central and southern Upper Rhine Graben: Insights from geothermal wells. Geothermics, 74, 57–73.
    [Google Scholar]
  13. Villeneuve, M., Heap, M.J., Kushnir, A.R.L., Qin, T., Baud, P., Zhou, G. and Xu, T
    . [2018] Estimating in-situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France). Geotherm. Energy, 6:11.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201901265
Loading
/content/papers/10.3997/2214-4609.201901265
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error