Volume 54 Number 1
  • E-ISSN: 1365-2478



Low frequencies are necessary in seismic data for proper acoustic impedance imaging and for petrophysical interpretation. Without lower frequencies, images can be distorted leading to incorrect reservoir interpretation and petrophysical predictions. As part of the Foinaven Active Reservoir Management (FARM) project, a Towed Streamer survey and an Ocean Bottom Hydrophone (OBH) survey were shot in both 1995 and 1998. The OBH surveys contain lower frequencies than the streamer surveys, providing a unique opportunity to study the effects that low frequencies have on both the acoustic impedance image along with petrophysical time‐lapse predictions. Artefacts that could easily have been interpreted as high‐resolution features in the streamer data impedance volumes can be distinguished by comparison with the impedance volumes created from the OBH surveys containing lower frequencies.

In order to obtain results from the impedance volumes, impedance must be related to saturation. The mixing of exsolved gas, oil and water phases involves using the Reuss (uniform) or Voigt (patchy approximation) mixing laws. The Voigt average is easily misused by assuming that the end‐points correspond to 0% and 100% gas saturation. This implies that the patches are either 0% gas saturation or 100% gas saturation, which is never the case. Here, the distribution of gas as it comes out of solution is assumed to be uniform until the gas saturation reaches a sufficiently high value (critical gas saturation) to allow gas to flow. Therefore, at low gas saturations the distribution is uniform, but at saturations above critical, it is patchy, with patches that range from critical gas saturation to the highest gas saturation possible (1 minus residual oil and irreducible water saturation).


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  1. BatzleM. and WangZ.1992. Seismic properties of pore fluids. Geophysics57, 1396–1408.
    [Google Scholar]
  2. BecqueyM., LavergneM. and WillmC.1979. Acoustic impedance logs computed from seismic traces. Geophysics44, 1485–1501.
    [Google Scholar]
  3. CooperM., ChristieP., ThorogoodE., KristiansenP., ProbertT. and WestwaterP.1999. Foinaven Active Reservoir Management: The benefits from the baseline surveys. 69th SEG Meeting, Houston , USA , Expanded Abstracts, 1636–1639.
  4. GhoshS.K.2000. Limitations on impedance inversion of band‐limited reflection data. Geophysics65, 951–957.
    [Google Scholar]
  5. HillS.J.2005. Inversion‐based thickness determination. The Leading Edge5, 477–480.
    [Google Scholar]
  6. KirstetterO.1999. The integration of laboratory data with flow simulation for application to seismic reservoir monitoring. PhD Thesis, Heriot‐Watt University .
  7. LatimerR.B., DavisonR. and Van RielP.2000. An interpreter's guide to understanding and working with seismic‐derived acoustic impedance data. The Leading Edge3, 242–256.
    [Google Scholar]
  8. LindsethR.O.1979. Synthetic sonic logs – a process for stratigraphic interpretation. Geophysics44, 3–26.
    [Google Scholar]
  9. MavkoG. and MukerjiT.1998. Bounds on low‐frequency seismic velocities in partially saturated rocks. Geophysics63, 918–924.
    [Google Scholar]
  10. MavkoG., MukerjiT. and DvorkinJ.1998. The Rock Physics Handbook: Tools for Seismic Analysis in Porous Media . Cambridge University Press.
    [Google Scholar]
  11. O'DonovanA.R., SmithS.G. and KristiansenP.2000. Foinaven 4D seismic –. Dynamic Reservoir Parameters and Reservoir Management 2000 SPE Annual Technical Conference and Exhibition , Dallas , USA , SPE 63294 .
  12. WagnerS.R., MacBethC. and PenningtonW.D.2003. Effects of spectral content on inversion for acoustic impedance, Foinaven Field. 65th EAGE Conference, Stavanger , Norway , Extended Abstracts, D24.

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  • Article Type: Research Article
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