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Stable Computation of the Vertical Gradient of Potential Field Data Based on Incorporating the Smoothing Filters

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Abstract

The vertical gradient is an essential tool in interpretation algorithms. It is also the primary enhancement technique to improve the resolution of measured gravity and magnetic field data, since it has higher sensitivity to changes in physical properties (density or susceptibility) of the subsurface structures than the measured field. If the field derivatives are not directly measured with the gradiometers, they can be calculated from the collected gravity or magnetic data using numerical methods such as those based on fast Fourier transform technique. The gradients behave similar to high-pass filters and enhance the short-wavelength anomalies which may be associated with either small-shallow sources or high-frequency noise content in data, and their numerical computation is susceptible to suffer from amplification of noise. This behaviour can adversely affect the stability of the derivatives in the presence of even a small level of the noise and consequently limit their application to interpretation methods. Adding a smoothing term to the conventional formulation of calculating the vertical gradient in Fourier domain can improve the stability of numerical differentiation of the field. In this paper, we propose a strategy in which the overall efficiency of the classical algorithm in Fourier domain is improved by incorporating two different smoothing filters. For smoothing term, a simple qualitative procedure based on the upward continuation of the field to a higher altitude is introduced to estimate the related parameters which are called regularization parameter and cut-off wavenumber in the corresponding filters. The efficiency of these new approaches is validated by computing the first- and second-order derivatives of noise-corrupted synthetic data sets and then comparing the results with the true ones. The filtered and unfiltered vertical gradients are incorporated into the extended Euler deconvolution to estimate the depth and structural index of a magnetic sphere, hence, quantitatively evaluating the methods. In the real case, the described algorithms are used to enhance a portion of aeromagnetic data acquired in Mackenzie Corridor, Northern Mainland, Canada.

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References

  • Abbas, M. A., & Fedi, M. (2014). Automatic DEXP imaging of potential fields independent of the structural index. Geophysical Journal International, 199, 1625–1632.

    Article  Google Scholar 

  • Abbas, M. A., Fedi, M., & Florio, G. (2014). Improving the local wavenumber method by automatic DEXP transformation. Journal of Applied Geophysics, 111, 250–255.

    Article  Google Scholar 

  • Baniamerian, J., Oskooi, B., & Fedi, M. (2017). Source imaging of potential fields through a matrix space-domain algorithm. Journal of Applied Geophysics, 136, 51–60.

    Article  Google Scholar 

  • Beiki, M. (2010). Analytic signals of gravity gradient tensor and their application to estimate source location. Geophysics, 75, I59–I74.

    Article  Google Scholar 

  • Blakely, R. J. (1996). Potential theory in gravity and magnetic applications. Cambridge: Cambridge University Press.

    Google Scholar 

  • Cella, F., Fedi, M., & Florio, G. (2009). Toward a full multiscale approach to interpret potential fields. Geophysical Prospecting, 57, 543–557.

    Article  Google Scholar 

  • Davis, K., Li, Y., & Nabighian, M. (2010). Automatic detection of UXO magnetic anomalies using extended Euler deconvolution. Geophysics, 75, G13–G20.

    Article  Google Scholar 

  • Davis, K., Li, Y., & Nabighian, M. N. (2011). Effects of low-pass filtering on the calculated structural index from magnetic data. Geophysics, 76, L23–L28.

    Article  Google Scholar 

  • De Lerma, D., Green, C., Cheyney, S., Campbell, S. (2015) Improved high order vertical derivatives of potential field data-extending the ISVD Method. In 77th EAGE Conference and Exhibition 2015.

  • Evjen, H. (1936). The place of the vertical gradient in gravitational interpretations. Geophysics, 1, 127–136.

    Article  Google Scholar 

  • Fedi, M. (2002). Multiscale derivative analysis: A new tool to enhance detection of gravity source boundaries at various scales. Geophysical Research Letters. https://doi.org/10.1029/2001GL013866.

    Google Scholar 

  • Fedi, M., & Florio, G. (2001). Detection of potential fields source boundaries by enhanced horizontal derivative method. Geophysical Prospecting, 49, 40–58.

    Article  Google Scholar 

  • Florio, G., Fedi, M., & Pasteka, R. (2006). On the application of Euler deconvolution to the analytic signal. Geophysics, 71(6), L87–L93.

    Article  Google Scholar 

  • Florio, G., Fedi, M., & Pašteka, R. (2014). On the estimation of the structural index from low-pass filtered magnetic data. Geophysics, 79(6), J67–J80.

    Article  Google Scholar 

  • Hannigan, P.K., Dixon, J., Morrow, D.W. (2009) Oil and gas resource potential in the Mackenzie corridor, northern mainland, Canada. In Proceedings Canadian Society of Petroleum Geologists Convention, pp. 66–70.

  • Hood, P. (1965). Gradient measurements in aeromagnetic surveying. Geophysics, 30, 891–902.

    Article  Google Scholar 

  • Keating, P., & Pilkington, M. (2004). Euler deconvolution of the analytic signal and its application to magnetic interpretation. Geophysical Prospecting, 52, 165–182.

    Article  Google Scholar 

  • Lahti, I., & Karinen, T. (2010). Tilt derivative multiscale edges of magnetic data. The Leading Edge, 29, 24–29.

    Article  Google Scholar 

  • Li, Y., Devriese, S. G., Krahenbuhl, R. A., & Davis, K. (2013). Enhancement of magnetic data by stable downward continuation for UXO application. IEEE Transactions on Geoscience and Remote Sensing, 51, 3605–3614.

    Article  Google Scholar 

  • Mushayandebvu, M., & Davies, J. (2006). Magnetic gradients in sedimentary basins: examples from the Western Canada Sedimentary Basin. The Leading Edge, 25, 69–73.

    Article  Google Scholar 

  • Nabighian, M. N. (1984). Toward a three-dimensional automatic interpretation of potential field data via generalized Hilbert transforms: fundamental relations. Geophysics, 49, 780–786.

    Article  Google Scholar 

  • Nabighian, M. N., Ander, M. E., Grauch, V. J. S., Hansen, R. O., LaFehr, T. R., Li, Y., et al. (2005a). Historical development of the gravity method in exploration. Geophysics, 70, 63–89.

    Article  Google Scholar 

  • Nabighian, M. N., Grauch, V. J. S., Hansen, R. O., LaFehr, T. R., Li, Y., Peirce, J. W., et al. (2005b). The historical development of the magnetic method in exploration. Geophysics, 70, 33–61.

    Article  Google Scholar 

  • Nabighian, M. N., & Hansen, R. O. (2001). Unification of Euler and Werner deconvolution in three dimensions via the generalized Hilbert transform. Geophysics, 66, 1805–1810.

    Article  Google Scholar 

  • Pašteka, R., Richter, F., Karcol, R., Brazda, K., & Hajach, M. (2009). Regularized derivatives of potential fields and their role in semi-automated interpretation methods. Geophysical Prospecting, 57, 507–516.

    Article  Google Scholar 

  • Pedersen, L. B., Bastani, M., & Kamm, J. (2015). Gravity gradient and magnetic terrain effects for airborne applications—a practical fast Fourier transform technique. Geophysics, 80, J19–J26.

    Article  Google Scholar 

  • Phillips, J.D. (2000) Locating magnetic contacts: a comparison of the horizontal gradient, analytic signal, and local wavenumber methods. In SEG Technical Program Expanded Abstracts 2000, pp. 402–405. Society of Exploration Geophysicists.

  • Phillips, J. D., Hansen, R. O., & Blakely, R. J. (2007). The use of curvature in potential-field interpretation. ASEG Extended Abstracts, 2006, 1–7.

    Article  Google Scholar 

  • Pilkington, M. (2007). Locating geologic contacts with magnitude transforms of magnetic data. Journal of Applied Geophysics, 63, 80–89.

    Article  Google Scholar 

  • Pilkington, M., & Keating, P. (2009). The utility of potential field enhancements for remote predictive mapping. Canadian Journal of Remote Sensing, 35, S1–S11.

    Article  Google Scholar 

  • Pilkington, M., & Tschirhart, V. (2017). Practical considerations in the use of edge detectors for geologic mapping using magnetic data. Geophysics, 82, J1–J8.

    Article  Google Scholar 

  • Richter, P., & Pašteka, R. (2003). Influence of norms on calculation of regularized derivatives in geophysics. Contributions to Geophysics and Geodesy, 33, 1–16.

    Google Scholar 

  • Roy, I. G. (2017). An alternative approach in establishing relation between vertical and horizontal gradients of 2D potential field. Geophysical Prospecting. https://doi.org/10.1111/1365-2478.12511.

    Google Scholar 

  • Salem, A., & Ravat, D. (2003). A combined analytic signal and Euler method (AN-EUL) for automatic interpretation of magnetic data. Geophysics, 68, 1952–1961.

    Article  Google Scholar 

  • Salem, A., Williams, S., Fairhead, D., Smith, R., & Ravat, D. (2007). Interpretation of magnetic data using tilt-angle derivatives. Geophysics, 73(1), L1–L10.

    Article  Google Scholar 

  • Thurston, J. B., & Smith, R. S. (1997). Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPI (TM) method. Geophysics, 62, 807–813.

    Article  Google Scholar 

  • Tikhonov, A., Glasko, V., Okl, L., & Melikhov, V. (1968). Analytic continuation of a potential in the direction of disturbing masses by the regularization method: Izvestiya. Physics of the Solid Earth, 12, 30–48. (in Russian; English translation: 738–747).

    Google Scholar 

  • Wang, B., Krebes, E. S., & Ravat, D. (2008). High-precision potential-field and gradient-component transformations and derivative computations using cubic B-splines. Geophysics, 73(5), I35–I42.

    Article  Google Scholar 

  • Yin, G., Zhang, Y., Mi, S., Fan, H., & Li, Z. (2016). Calculation of the magnetic gradient tensor from total magnetic anomaly field based on regularized method in frequency domain. Journal of Applied Geophysics, 134, 44–54.

    Article  Google Scholar 

Download references

Acknowledgements

We would like to thank the Editor, Hans-Jürgen Götze, and the reviewers Giovanni Florio and Roman Pašteka for their thoughtful comments and criticisms which helped us to improve the original manuscript. The Geological Survey of Canada is appreciated to permit to use the aeromagnetic data set. This research was supported by grants from the NSF of China and Hubei Province (Nos. 41604087, 2016CFB122), the China Postdoctoral Science Foundation (No. 2016M590132), and the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (CUGL170407, CUG160609).

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Correspondence to Shuang Liu.

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Baniamerian, J., Liu, S. & Abbas, M.A. Stable Computation of the Vertical Gradient of Potential Field Data Based on Incorporating the Smoothing Filters. Pure Appl. Geophys. 175, 2785–2806 (2018). https://doi.org/10.1007/s00024-018-1857-2

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