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Volume 70, Issue 4
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

Understanding the electrical properties of reservoir rocks has important applications in oil and gas exploration. Small‐scale fractures that are widely existing in reservoir rocks are usually aligned along a certain preferential direction due to reasons such as tectonic movement, making the electrical conductivity of the rocks anisotropic. Since all rocks are experiencing geological pressure, it is theoretically and practically important to study the influence of pressure on the fractures and its control on the anisotropic conductivity of reservoir rocks. We first prepared artificial porous sandstone samples with and without penny‐shaped fractures and experimentally measured the anisotropic conductivity of the samples under differential pressure (the difference between confining pressure and pore fluid pressure). Then, we inverted from the experimental data for the fracture porosity and fracture aspect ratio at each differential pressure. The variation of the fracture parameters caused by the differential pressure and their influence on the anisotropic electrical conductivity of the rocks were further analysed theoretically. The results show that as the differential pressure increases, the measured anisotropic conductivity of the artificial samples with and without fractures all decreases exponentially. We also show that both the inverted fracture porosity and fracture aspect ratio decrease exponentially with the increase of differential pressure, and the fracture porosity and fracture aspect ratio are linearly correlated as an implicit function of differential pressure. The modelling results show that the differential pressure‐induced decrease in the fracture porosity reduces the electrical conductivity in all directions, and the conductivity reduction in the rock parallel to the direction of the fractures is most significant. Comparing with the influence of the fracture porosity resulting from the applied differential pressure, the pressure‐caused variation in the fracture aspect ratio was shown to play a secondary role on affecting the pressure‐dependent anisotropic electrical properties.

© 2022 European Association of Geoscientists & Engineers © 2022 European Association of Geoscientists & Engineers
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2022-04-14
2024-04-19

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References

  1. Amalokwu, K., Chapman, M., Best, A.I., Minshull, T.A. and Li, X.‐Y. (2015) Water saturation effects on P‐wave anisotropy in synthetic sandstone with aligned fractures. Geophysical Journal International, 202(2), 1088–1095.
     [Google Scholar]
  2. Archie, G.E. (1942) The electrical resistivity log as an aid in determining some reservoir characteristics. Transactions of the AIME, 146, 54–64.
     [Google Scholar]
  3. Barthélémy, J.F. (2009) Effective permeability of media with a dense network of long and micro fractures. Transport in Porous Media, 76(1), 153–178.
     [Google Scholar]
  4. Cassidy, R., Comte, J.C., Nitsche, J., Wilson, C., Flynn, R. and Ofterdinger, U. (2014) Combining multi‐scale geophysical techniques for robust hydro‐structural. Journal of Hydrology, 517, 715–731.
     [Google Scholar]
  5. Chen, G.Y., Cai, L., Qin, G.Y. and Zhang, Z.X. (2009) Experiment on the crack‐electrical resistance variation with compressive stress of siliceous‐lime marble. Isrm‐sponsored International Symposium on Rock, No.122.
  6. Chen, W., Heinz, K. and Syed, M.A. (2015) Numerical simulation of time‐independent and ‐dependent fracturing in sandstone. Engineering Geology, 193(2), 118–131.
     [Google Scholar]
  7. Constable, S. (2010) Ten years of marine CSEM for hydrocarbon exploration. Geophysics, 75(5), 75A67–75A81.
     [Google Scholar]
  8. Ding, P., Di, B., Wang, D., Wei, J. and Li, X. (2017) Measurements of seismic anisotropy in synthetic rocks with controlled crack geometry and different crack densities. Pure and Applied Geophysics, 174, 1907–1922.
     [Google Scholar]
  9. Duan, H.L., Karihaloo, B.L., Wang, J. and Yi, X. (2006) Effective conductivities of heterogeneous media containing multiple inclusions with various spatial distributions. Physics Review B, 73(17), 174203.
     [Google Scholar]
  10. Falcon‐Suarez, I.H., North, L., Callow, B., Bayrakci, G., Bull, J. and Best, A. (2020) Experimental assessment of the stress‐sensitivity of combined elastic and electrical anisotropy in shallow reservoir sandstones. Geophysics, 85(5), MR271–MR283.
     [Google Scholar]
  11. Giraud, A., Gruescu, C., Do, D.P., Homanda, F. and Kondoc, D. (2007) Effective thermal conductivity of transversely isotropic media with arbitrary oriented ellipsoïdal inhomogeneities. International Journal of Solids and Structures, 44(9), 2627–2647.
     [Google Scholar]
  12. Giraud, A., Sevostianov, I., Kushch, V.I., Cosenza, P., Pret, D., Barthelemy, J.F. and Trofimov, A. (2019) Effective electrical conductivity of transversely isotropic rocks with arbitrarily oriented ellipsoidal inclusions. Mechanics of Materials, 133, 174–192.
     [Google Scholar]
  13. Han, T. (2018) Joint elastic‐electrical properties of artificial porous sandstone with aligned fractures. Geophysical Research Letters, 45(7), 3051–3058.
     [Google Scholar]
  14. Han, T., Gurevich, B., Fu, L.‐Y., Qi, Q., Wei, J. and Chen, X. (2020a) Combined effects of pressure and water saturation on the seismic anisotropy in artificial porous sandstone with aligned fractures. Journal of Geophysical Research: Solid Earth, 125, e2019JB019091.
     [Google Scholar]
  15. Han, T., Josh, M. and Liu, H. (2019) Effects of aligned fractures on the dielectric properties of synthetic porous sandstones. Journal of Petroleum Science and Engineering, 172, 436–442.
     [Google Scholar]
  16. Han, T., Wei, Z. and Li, F. (2020b) How the effective pore and grain shapes are correlated in Berea sandstones: implications for joint elastic‐electrical modeling. Geophysics, 85(3), MR147–MR154.
     [Google Scholar]
  17. Henriques, J.P., De Figueiredo, J.J.S., Santos, L.K., Macedo, D.L., Coutinho, I., da Silva, C.B.et al. (2018) Experimental verification of effective anisotropic crack theories in variable crack aspect ratio medium. Geophysical Prospecting, 66(1), 141–156.
     [Google Scholar]
  18. Hill, R.J. (1963) Elastic properties of reinforced solids: some theoretical principles. Journal of the Mechanics and Physics of Solids, 11(5), 357–372.
     [Google Scholar]
  19. Hornby, B.E. (1998) Experimental laboratory determination of the dynamic elastic properties of wet, drained shales. Journal of Geophysical Research: Solid Earth, 103, 29945–29964.
     [Google Scholar]
  20. Kuvshinov, A.V. (2012) Deep electromagnetic studies from land, sea, and space: progress status in the past 10 years. Surveys in Geophysics, 33, 9–29.
     [Google Scholar]
  21. Lee, S., Lee, J., Ryu, B. and Ryu, S. (2018) A micromechanics‐based analytical solution for the effective thermal conductivity of composites with orthotropic matrices and interfacial thermal resistance. Scientific Reports, 8(1), 1–11.
     [Google Scholar]
  22. Mura, T. (1987) Micromechanics of defects in solids. Distributors for the U.S. and Canada: Kluwer Academic Publishers.
     [Google Scholar]
  23. Napo, B., Cynthia, D. and Hafid, S. (2017) Micromechanical modeling of the anisotropic thermal conductivity of ellipsoidal inclusion‐reinforced composite materials with weakly conducting interfaces. International Journal of Heat and Mass Transfer, 108, 1727–1739.
     [Google Scholar]
  24. Popov, Y., Tertychnyi, V., Romushkevich, R., Korobkov, D. and Pohl, J. (2003) Interrelations between thermal conductivity and other physical properties of rocks: Experimental data. Pure and Applied Geophysics, 160(5‐6), 1137–1161.
     [Google Scholar]
  25. Rathore, J.S., Fjaer, E., Holt, R.M. and Renlie, L. (1995) P‐ and S‐wave anisotropy of a synthetic sandstone with controlled crack geometry. Geophysical Prospecting, 43(6), 711–728.
     [Google Scholar]
  26. Ren, S., Han, T., Fu, L.‐Y. and Yan, H. (2021) Pressure effects on the anisotropic velocities of rocks with aligned fractures. Chinese Journal of Geophysics, 64(7), 2504–2514 (in Chinese).
     [Google Scholar]
  27. Sævik, P.N., Berre, I., Jakobsen, M. and Lien, M. (2013) A 3d computational study of effective medium methods applied to fractured media. Transport in Porous Media, 100(1), 115–142.
     [Google Scholar]
  28. Sarout, J., Cazes, E., Delle, P.C., Arena, A. and Esteban, L. (2017) Stress‐dependent permeability and wave dispersion in tight cracked rocks: experimental validation of simple effective medium models. Journal of Geophysical Research: Solid Earth, 122(8), 6180–6201.
     [Google Scholar]
  29. Shafiro, B. and Kachanov, M. (2000) Anisotropic effective conductivity of materials with nonrandomly oriented inclusions of diverse ellipsoidal shapes. Journal of Applied Physics, 87(12), 8561–8569.
     [Google Scholar]
  30. Shao, T., Ji, S., Li, J., Qian, W. and Song, M. (2011) Paterson gas‐medium high‐pressure high‐temperature testing system and its applications in rheology of rocks. Geotectonica et Metallogenia, 35(3), 457–476.
     [Google Scholar]
  31. Shapiro, S.A. (2003) Elastic piezosensitivity of porous and fractured rocks. Geophysics, 68, 482–486.
     [Google Scholar]
  32. Shen, J.S., Su, B.Y. and Guo, N.C. (2009) Study on the anisotropic characteristics of the electric response to fractured reservoir. Chinese Journal of Geophysics, 52(11), 2903–2912 (in Chinese).
     [Google Scholar]
  33. Tillotson, P., Sothcott, J., Best, A.I., Chapman, M. and Li, X.Y. (2012) Experimental verification of the fracture density and shear‐wave splitting relationship using synthetic silica cemented sandstones with a controlled fracture geometry. Geophysical Prospecting, 60, 516–525.
     [Google Scholar]
  34. Tohru, W. and Akiyoshi, H. (2015) Simultaneous measurements of elastic wave velocities and electrical conductivity in a brine‐saturated granitic rock under confining pressures and their implication for interpretation of geophysical observations. Progress in Earth and Planetary Science, 2(1), 1–12.
     [Google Scholar]
  35. Vernik, L. and Nur, A. (1992) Ultrasonic velocity and anisotropy of hydrocarbon source rocks. Geophysics, 57(5), 727–735.
     [Google Scholar]
  36. Wang, T. and Tang, X. (2005) Multipole acoustic responses of a prestressed formation: an effective medium approach. Geophysics, 70(2), F35–F44.
     [Google Scholar]
  37. Wang, Z., Wang, R., Wang, F., Qiu, H. and Li, T. (2015) Experiment study of pore structure effects on velocities in synthetic carbonate rocks. Geophysics, 80(3), D207–D219.
     [Google Scholar]
  38. Xu, S., Tang, X., Torres‐Verdín, C. and Su, Y. (2018) Seismic shear wave anisotropy in cracked rocks and an application to hydraulic fracturing. Geophysical Research Letters, 45(11), 5390–5397.
     [Google Scholar]
  39. Yan, H., Han, T. and Fu, L.‐Y. (2020) Theoretical models for the effective electrical conductivity of transversely isotropic rocks with inclined penny‐shaped cracks. Journal of Geophysical Research: Solid Earth, 125, e2020JB020371.
     [Google Scholar]
  40. Yoshida, S., Clint, O.C. and Sammonds, P.R. (1998) Electric potential changes prior to shear fracture in dry and saturated rocks. Geophysical Research Letters, 25(10), 1577–1580.
     [Google Scholar]
  41. Young, P.D. and Cox, C.S. (1981) Electromagnetic active source sounding near the East Pacific Rise. Geophysical Research Letters, 8, 1043–1046.
     [Google Scholar]
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Pressure effects on the anisotropic electrical conductivity of artificial porous rocks with aligned fractures
Geophysical Prospecting 70, 790 (2022); https://doi.org/10.1111/1365-2478.13184
/content/journals/10.1111/1365-2478.13184
/content/journals/10.1111/1365-2478.13184
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  • Article Type: Research Article
Keyword(s): Fracture; Resistivity; Rock physics

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