1887
Volume 63 Number 1
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

We compare selected marine electromagnetic methods for sensitivity to the presence of relatively thin resistive targets (e.g., hydrocarbons, gas hydrates, fresh groundwater, etc.). The study includes the conventional controlled‐source electromagnetic method, the recently introduced transient electromagnetic prospecting with vertical electric lines method, and the novel marine circular electric dipole method, which is still in the stage of theoretical development. The comparison is based on general physical considerations, analytical (mainly asymptotic) analysis, and rigorous one‐dimensional and multidimensional forward modelling. It is shown that transient electromagnetic prospecting with vertical electric lines and marine circular electric dipole methods represent an alternative to the conventional controlled‐source electromagnetic method at shallow sea, where the latter becomes less efficient due to the air‐wave phenomenon. Since both former methods are essentially short‐offset time‐domain techniques, they exhibit a much better lateral resolution than the controlled‐source electromagnetic method in both shallow sea and deep sea. The greatest shortcoming of the transient electromagnetic prospecting with vertical electric lines and marine circular electric dipole methods comes from the difficulties in accurately assembling the transmitter antenna within the marine environment. This makes these methods significantly less practical than the controlled‐source electromagnetic method. Consequently, the controlled‐source electromagnetic method remains the leading marine electromagnetic technique in the exploration of large resistive targets in deep sea. However, exploring laterally small targets in deep sea and both small and large targets in shallow sea might require the use of the less practical transient electromagnetic prospecting with vertical electric lines and/or marine circular electric dipole method as a desirable alternative to the controlled‐source electromagnetic method.

Loading

Article metrics loading...

/content/journals/10.1111/1365-2478.12151
2014-09-16
2024-04-18
Loading full text...

Full text loading...

References

  1. AlumbaughD., CuevasN.H., ChenJ., GaoG. and BradyJ.2010. Comparison of sensitivity and resolution with two marine CSEM exploration methods. 80th SEG Annual Meeting, Denver, Colorado, Expanded Abstracts, 3893–3896.
  2. ChaveA.D. and CoxC.S.1982. Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans: Part 1—Forward problem and model study. Journal of Geophysical Research87, 5327–5338.
    [Google Scholar]
  3. Chave, A.D.2009. On the electromagnetic fields produced by marine frequency domain controlled sources. Geophysical Journal Inter­national179, 1429–1457.
    [Google Scholar]
  4. CommerM. and NewmanG.2008. New advances in three‐dimensional controlled‐source electromagnetic inversion. Geophysical Journal Inter­national172, 513–535.
    [Google Scholar]
  5. ConnellD. and KeyK.2013. A numerical comparison of time and frequency‐domain marine electromagnetic methods for hydrocarbon exploration in shallow water. Geophysical Prospecting 61, 187–199.
    [Google Scholar]
  6. ConstableS.2006. Marine electromagnetic methods—A new tool for offshore exploration. The Leading Edge25, 438–444.
    [Google Scholar]
  7. ConstableS.2010. Ten years of marine CSEM for hydrocarbon exploration. Geophysics75, 75A67–75A81
    [Google Scholar]
  8. ConstableS. and SrnkaL.J.2007. An introduction to marine controlled source electromagnetic methods for hydrocarbon exploration. Geophys­ics72, WA3–WA12.
    [Google Scholar]
  9. ConstableS. and WeissC.J.2006. Mapping thin resistors and hydrocar­bons with marine EM methods: Insights from 1D modeling. Geophysics71, G43–G51.
    [Google Scholar]
  10. CoxC.S.1981. On the electrical conductivity of the oceanic lithosphere. Physics of the Earth and Planetary Interiors25, 196–201.
    [Google Scholar]
  11. CuevasN.H. and AlumbaughD.2011. Near‐source response of a resistive layer to a vertical or horizontal electric dipole excitation. Geophysics76, F353–F371.
    [Google Scholar]
  12. DruskinV.L. and KnizhnermanL.A.1988. A spectral semi‐discrete method for the numerical solution of three‐dimensional non‐stationary electrical prospecting problems. Izvestiya, Physics of the Solid Earth8, 63–74.
    [Google Scholar]
  13. EdwardsN.2005. Marine controlled source electromagnetics: principles, methodologies, future commercial applications. Surveys in Geophysics26, 675–700.
    [Google Scholar]
  14. EdwardsR.N., LawL.K. and DeLaurierJ.M.1981. On measuring the electrical conductivity of the ocean crust by a modified magnetometric resistivity method. Journal of Geophysical Research86, 11609–11615.
    [Google Scholar]
  15. EdwardsR.N., LawL.K., WolfgramP.A., NobesD.C., BoneM.N., TriggD.F.et al. 1985. First results of the MOSES experiment: sea sediment conductivity and thickness determination, bute inlet, British Columbia, by magneto‐metric off‐shore electrical sounding. Geophysics50, 153–160.
    [Google Scholar]
  16. EllingsrudS., EidesmoT., JohansenS., SinhaM.C., MacGregorL.M. and ConstableS.C.2002. Remote sensing of hydrocarbon layers by seabed imaging (SBL): results from a cruise offshore Angola. The Leading Edge21, 972–982.
    [Google Scholar]
  17. GoldmanM.1983. The integral‐finite‐difference method for calculating transient electromagnetic fields in a horizontally stratified medium. Geophysical Prospecting31, 664–686.
    [Google Scholar]
  18. GoldmanM.1987. Forward modelling for frequency domain marine electromagnetic systems. Geophysical Prospecting35, 1042–1064.
    [Google Scholar]
  19. GoldmanM.1990. Non‐Conventional Methods in Geoelectrical Prospecting. Ellis Horwood Ltd.
    [Google Scholar]
  20. GoldmanM. and FittermanD.1987. Direct time‐domain calculation of the transient response for a rectangular loop over a two‐layered medium. Geophysics52, 997–1006.
    [Google Scholar]
  21. GoldmanM., LeviE., TezkanB. and Yogeshwar, P. 2011. The 2D coastal effect on marine time domain electromagnetic measurements using broadside dBz/dt of an electrical transmitter dipole. Geophysics76, F101–F109.
    [Google Scholar]
  22. GoldmanM. and MogilatovV.1978. Transient field of a vertical electric dipole embedded in a horizontally layered half‐space (in Russian). In: Theory and Applications of Electromagnetic Fields in Geophysical Exploration. Academy of Science of the USSR, Siberian Branch, 123–138.
    [Google Scholar]
  23. GoldmanM, TabarovskyL. and RabinovichM.1994. On the influence of three‐dimensional structures in the interpretation of transient electromagnetic sounding data. Geophysics59, 889–901.
    [Google Scholar]
  24. HolladayJ.S.1981. YVESFT and CHANNEL, A Subroutine Package for Stable Transformation of Sparse Frequency Domain Electromagnetic Data to the Time Domain. Research in Applied Geophysics17, Geophysics Laboratory, University of Toronto.
    [Google Scholar]
  25. HoltenT., FlekkøyE.G., MåløyK.J. and SingerB.2009. Vertical source and receiver CSEM method in time‐domain. 79th SEG Annual Meeting, Houston, Texas, Expanded Abstracts, 749–752.
  26. KaufmanA.1978. Frequency and transient responses of electromagnetic fields created by currents in confined conductors. Geophysics43, 1002–1010.
    [Google Scholar]
  27. KaufmanA., GoldmanM., LeeD.S. and KellerG.1981. Marine electromagnetic prospecting system. 51st SEG Annual Meeting, Abstracts and Biographies, 21.
  28. KaufmanA.A. and KellerG.V.1983. Frequency and transient soundings. Elsevier Science Publishers B.V.
    [Google Scholar]
  29. KeyK.2009. 1D inversion of multicomponent, multifrequency marine CSEM data: Methodology and synthetic studies for resolving thin resistive layers. Geophysics74, F9–F20.
    [Google Scholar]
  30. LosethL.O. and AmundsenL.2007. On the signal propagation in marine CSEM. 69th EAGE Conference and Exhibition, Extended Abstracts, D035.
  31. MogilatovV.1992. A circular electric dipole as a new source in electric surveys. Izvestiya, Physics of the Solid Earth6, 97–105.
    [Google Scholar]
  32. MogilatovV.1996. Excitation of a half‐space by a radial current sheet source. Pure and Applied Geophysics14(7), 763–775.
    [Google Scholar]
  33. MogilatovV. and BalashovB.1996. A new method of geoelectrical prospecting by vertical electric current soundings. Journal of Applied Geophysics36, 31–41.
    [Google Scholar]
  34. NazarenkoO.1961. Electrical device for marine exploration. USSR patent 751834/26–10.
    [Google Scholar]
  35. SchollC. and EdwardsR.N.2007. Marine downhole to seafloor dipole‐dipole electromagnetic methods and the resolution of resistive targets. Geophysics72, WA39–WA49.
    [Google Scholar]
  36. SingerB.S. and AtramonovaS.2013. Vertical electric source in transient marine CSEM: Effect of 3D inhomogeneities on the late time response. Geophysics78, E173–E188.
    [Google Scholar]
  37. StolzE.M. and MacnaeJ.1998. Evaluating EM waveforms by singular‐ value decomposition of exponential basis functions. Geophysics63, 64–74.
    [Google Scholar]
  38. TikhonovA.N.1950. On transient electric currents in an inhomogeneous layered medium. Izvestiya, Physics of the Solid Earth14.
    [Google Scholar]
  39. UmE.S. and AlumbaughD.L.2007. On the physics of the marine controlled‐source electromagnetic method. Geophysics72, WA13–WA26.
    [Google Scholar]
  40. UmE.S., AlumbaughD.L., HarrisJ.M. and ChenJ.2012. Numerical modeling analysis of short‐offset electric‐field measurements with a vertical electric dipole source in complex offshore environments. Geophysics77, E329–E341.
    [Google Scholar]
  41. WaitJ.R.1982. Geo‐Electromagnetism. Academic Press.
    [Google Scholar]
  42. WeideltP.2007. Guided waves in marine CSEM. Geophysical Journal International171, 153–176.
    [Google Scholar]
  43. WeissC.J. and ConstableS.2006. Mapping thin resistors and hydrocar­bons with marine EM methods: Part 2—Modeling and analysis in 3D. Geophysics71, G321–G332.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/1365-2478.12151
Loading
/content/journals/10.1111/1365-2478.12151
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): Marine electromagnetics; Resistive targets; Signal detectability

Most Cited This Month Most Cited RSS feed

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