This website uses cookies to improve your experience. If you continue without changing your settings, you consent to our use of cookies in accordance with our cookie policy. You can disable cookies at any time.

×
Advanced search
Skip main navigation
Close Drawer MenuOpen Drawer Menu

Previous
Next
No AccessGEOPHYSICSVolume 80, Issue 2

Challenges and opportunities for fractured rock imaging using 3D cross-borehole electrical resistivity

Authors:
https://doi.org/10.1190/geo2014-0138.1

ABSTRACT

There is an increasing need to characterize discrete fractures away from boreholes to better define fracture distributions and monitor solute transport. We performed a 3D evaluation of static and time-lapse cross-borehole electrical resistivity tomography (ERT) data sets from a limestone quarry in which flow and transport are controlled by a bedding-plane feature. Ten boreholes were discretized using an unstructured tetrahedral mesh, and 2D panel measurements were inverted for a 3D distribution of conductivity. We evaluated the benefits of 3D versus 2.5D inversion of ERT data in fractured rock while including the use of borehole regularization disconnects (BRDs) and borehole conductivity constraints. High-conductivity halos (inversion artifacts) surrounding boreholes were removed in static images when BRDs and borehole conductivity constraints were implemented. Furthermore, applying these constraints focused transient changes in conductivity resulting from solute transport on the bedding plane, providing a more physically reasonable model for conductivity changes associated with solute transport at this fractured rock site. Assuming bedding-plane continuity between fractures identified in borehole televiewer data, we discretized a planar region between six boreholes and applied a fracture regularization disconnect (FRD). Although the FRD appropriately focused conductivity changes on the bedding plane, the conductivity distribution within the discretized fracture was nonunique and dependent on the starting homogeneous model conductivity. Synthetic studies performed to better explain field observations showed that inaccurate electrode locations in boreholes resulted in low-conductivity halos surrounding borehole locations. These synthetic studies also showed that the recovery of the true conductivity within an FRD depended on the conductivity contrast between the host rock and fractures. Our findings revealed that the potential exists to improve imaging of fractured rock through 3D inversion and accurate modeling of boreholes. However, deregularization of localized features can result in significant electrical conductivity artifacts, especially when representing features with a high degree of spatial uncertainty.

REFERENCES

  • Backus, G., and F. Gilbert, 1968, The resolving power of gross earth data: Geophysical Journal International, 16, 169–205, doi: 10.1111/j.1365-246X.1968.tb00216.x.GJINEA0956-540XCrossrefWeb of ScienceGoogle Scholar
  • Barker, J. A., 1981, A formula for estimating fissure transmissivities from steady-state injection-test data: Journal of Hydrology, 52, 337–346, doi: 10.1016/0022-1694(81)90179-7.JHYDA70022-1694CrossrefWeb of ScienceGoogle Scholar
  • Bazin, S., and A. Pfaffhuber, 2013, Mapping of quick clay by electrical resistivity tomography under structural constraint: Journal of Applied Geophysics, 98, 280–287, doi: 10.1016/j.jappgeo.2013.09.002.JAGPEA0926-9851CrossrefWeb of ScienceGoogle Scholar
  • Binley, A., and A. Kemna, 2005, DC resistivity and induced polarization methods, in Rubin, Y.S. Hubbard, eds., Hydrogeophysics, vol. 50, Springer, 129–156.CrossrefGoogle Scholar
  • Brown, D., and L. D. Slater, 1999, Focused packer testing using geophysical tomography and CCTV in a fissured aquifer: Quarterly Journal of Engineering Geology, 32, 173–183, doi: 10.1144/GSL.QJEG.1999.032.P2.07.QJEGA70481-2085CrossrefWeb of ScienceGoogle Scholar
  • Chambers, J. E., R. D. Ogilvy, O. Kuras, J. C. Cripps, and P. I. Meldrum, 2002, 3D electrical imaging of known targets at a controlled environmental test site: Environmental Geology, 41, 690–704, doi: 10.1007/s00254-001-0452-4.CrossrefWeb of ScienceGoogle Scholar
  • Coscia, I., S. A. Greenhalgh, N. Linde, J. Doetsch, L. Marescot, T. Gu, and A. G. Green, 2011, 3D crosshole ERT for aquifer characterization and monitoring of infiltrating river water: Geophysics, 76, no. 2, G49–G59, doi: 10.1190/1.3553003.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • DeGroot-Hedlin, C., and S. Constable, 1990, Occam’s inversion to generate smooth , two-dimensional models from magnetotelluric data: Geophysics, 55, 1613–1624, doi: 10.1190/1.1442813.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Doetsch, J., I. Coscia, S. Greenhalgh, N. Linde, A. Green, and T. Günther, 2010, The borehole-fluid effect in electrical resistivity imaging: Geophysics, 75, no. 4, F107–F114, doi: 10.1190/1.3467824.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Doetsch, J., N. Linde, M. Pessognelli, A. G. Green, and T. Günther, 2012, Constraining 3-D electrical resistance tomography with GPR reflection data for improved aquifer characterization: Journal of Applied Geophysics, 78, 68–76, doi: 10.1016/j.jappgeo.2011.04.008.JAGPEA0926-9851CrossrefWeb of ScienceGoogle Scholar
  • Farquharson, C. G., 2008, Constructing piecewise-constant models in multidimensional minimum-structure inversions: Geophysics, 73, no. 1, K1–K9, doi: 10.1190/1.2816650.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Günther, T., C. Rücker, and K. Spitzer, 2006, Three-dimensional modelling and inversion of dc resistivity data incorporating topography — Part II: Inversion: Geophysical Journal International, 166, 506–517, doi:10.1111/j.1365-246X.2006.03011.x.GJINEA0956-540XCrossrefWeb of ScienceGoogle Scholar
  • Johnson, T. C., R. J. Versteeg, M. Rockhold, L. D. Slater, D. Ntarlagiannis, W. J. Greenwood, and J. Zachara, 2012, Characterization of a contaminated wellfield using 3D electrical resistivity tomography implemented with geostatistical, discontinuous boundary, and known conductivity constraints: Geophysics, 77, no. 6, EN85–EN96, doi: 10.1190/geo2012-0121.1.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Johnson, T. C., R. J. Versteeg, A. Ward, F. D. Day-Lewis, and A. Revil, 2010, Improved hydrogeophysical characterization and monitoring through parallel modeling and inversion of time-domain resistivity and induced-polarization data: Geophysics, 75, no. 4, WA27–WA41, doi: 10.1190/1.3475513.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Koestel, J., A. Kemna, M. Javaux, A. Binley, and H. Vereecken, 2008, Quantitative imaging of solute transport in an unsaturated and undisturbed soil monolith with 3-D ERT and TDR: Water Resources Research, 44, W12411, doi: 10.1029/2007WR006755.WRERAQ0043-1397CrossrefWeb of ScienceGoogle Scholar
  • Labrecque, D., and X. Yang, 2001, Difference inversion of ERT data : a fast inversion method for 3-D in situ monitoring: Journal of Environmental and Engineering Geophysics, 6, 83–89, doi: 10.4133/JEEG6.2.83.1083-1363AbstractGoogle Scholar
  • LaBrecque, D. J., M. Miletto, W. Daily, A. Ramirez, and E. Owen, 1996, The effects of noise on Occam’s inversion of resistivity tomography data: Geophysics, 61, 538–548, doi: 10.1190/1.1443980.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Oldenborger, G. A., P. S. Routh, and M. D. Knoll, 2005, Sensitivity of electrical resistivity tomography data to electrode position errors: Geophysical Journal International, 163, 1–9, doi: 10.1111/j.1365-246X.2005.02714.x.GJINEA0956-540XCrossrefWeb of ScienceGoogle Scholar
  • Orlando, L., 2013, GPR to constrain ERT data inversion in cavity searching: Theoretical and practical applications in archeology: Journal of Applied Geophysics, 89, 35–47, doi: 10.1016/j.jappgeo.2012.11.006.JAGPEA0926-9851CrossrefWeb of ScienceGoogle Scholar
  • Robinson, J., T. Johnson, and L. Slater, 2013, Evaluation of known-boundary and resistivity constraints for improving cross-borehole DC electrical resistivity imaging of discrete fractures: Geophysics, 78, no. 3, D115–D127, doi: 10.1190/geo2012-0333.1.AbstractWeb of ScienceGoogle Scholar
  • Rorabaugh, M. J., 1953, Graphical and theoretical analysis of step-drawdown test of Artesian well: American Society of Civil Engineers.Google Scholar
  • Sasaki, Y., 1994, 3-D resistivity inversion using the finite-element method: Geophysics, 59, 1839–1848, doi: 10.1190/1.1443571.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Si, H., 2006, TetGen: A quality tetrahedral mesh generator and three-dimensional Delaunay triangulator: Weierstrass Institute for Applied Analysis and Stochastics.Google Scholar
  • Slater, L., and A. Binley, 2006, Synthetic and field-based electrical imaging of a zerovalent iron barrier: Implications for monitoring long-term barrier performance: Geophysics, 71, no. 5, B129–B137. doi: 10.1190/1.2235931.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar
  • Slater, L., A. Binley, and D. Brown, 1997, Electrical imaging of fractures using ground-water salinity change: Ground Water, 35, 436–442, doi: 10.1111/j.1745-6584.1997.tb00103.x.GRWAAP0017-467XCrossrefWeb of ScienceGoogle Scholar
  • Slater, L. D., D. Brown, and A. Binley, 1996, Determination of hydraulically conductive pathways in fractured limestone using cross-borehole electrical resistivity tomography: European Journal of Environmental and Engineering Geophysics, 1, 35–52.1359-8155Google Scholar
  • Wallin, E. L., T. C. Johnson, W. J. Greenwood, and J. M. Zachara, 2013, Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2-D time-lapse surface electrical resistivity tomography, Water Resources Research, 49, 1693–1708, doi: 10.1002/wrcr.20119.CrossrefGoogle Scholar
  • Wilkinson, P. B., J. E. Chambers, M. Lelliott, G. P. Wealthall, and R. D. Ogilvy, 2008, Extreme sensitivity of crosshole electrical resistivity tomography measurements to geometric errors: Geophysical Journal International, 173, 49–62, doi: 10.1111/j.1365-246X.2008.03725.x.GJINEA0956-540XCrossrefWeb of ScienceGoogle Scholar
  • Wilkinson, P. B., J. E. Chambers, P. I. Meldrum, R. D. Ogilvy, and S. Caunt, 2006, Optimization of array configurations and panel combinations for the detection and imaging of abandoned mineshafts using 3D cross-hole electrical resistivity tomography: Journal of Environmental & Engineering Geophysics, 11, 213–221, doi: 10.2113/JEEG11.3.213.AbstractWeb of ScienceGoogle Scholar
  • Zhang, J., 1995, 3-D resistivity forward modeling and inversion using conjugate gradients: Geophysics, 60, 1313–1325, doi: 10.1190/1.1443868.GPYSA70016-8033AbstractWeb of ScienceGoogle Scholar