Stack-related and nonstack-related mechanisms for the generation of low-frequency anomalies: Examples from Johan Sverdrup field, central North Sea

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2017Stack-related and nonstack-related mechanisms for the generation of low-frequency anomalies: Examples from Johan Sverdrup field, central North SeaAuthors: Sayyid Suhail AhmadWiktor Waldemar WeibullAlejandro EscalonaRobert James BrownSayyid Suhail AhmadUniversity of StavangerSearch for more papers by this author, Wiktor Waldemar WeibullUniversity of StavangerSearch for more papers by this author, Alejandro EscalonaUniversity of StavangerSearch for more papers by this author, and Robert James BrownUniversity of Stavanger and Skagen44 ASSearch for more papers by this authorhttps://doi.org/10.1190/segam2017-17739843.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract Using the Gabor-Morlet transform, we have investigated low-frequency amplitude anomalies from the highly permeable Intra-Draupne Fm and the fractured Tor Fm. For this purpose we used a 3D broadband seismic dataset from Johan Sverdrup field in the central North Sea. We observed low Q values of about 25 or 30 from the highly permeable Upper Jurassic Intra-Draupne Fm. The low-frequency amplitude anomalies from the Intra-Draupne Fm were observed in areas where the reservoir is relatively thick. We performed a three-layer elastic modeling, whose results suggest that, as the thickness of the middle, gas-saturated layer increases, the dominant frequency decreases due to the tuning effect, which one needs to be aware of in evaluating low-frequency amplitude anomalies. But, over and above this, the low-frequency anomalies observed from the fractured Tor Fm seem to show a clear correlation with zones of increased fracture density interpreted from the high-resolution most-negative-curvature attribute. In addition, stacking of seismic data was carried out using both coarse and fine velocity analysis. The resulting low-frequency anomalies were not found to be stack-related. Presentation Date: Wednesday, September 27, 2017 Start Time: 1:50 PM Location: Exhibit Hall C/D Presentation Type: POSTER Keywords: fractures, low frequency, spectral, amplitude, attributesPermalink: https://doi.org/10.1190/segam2017-17739843.1FiguresReferencesRelatedDetails SEG Technical Program Expanded Abstracts 2017ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2017 Pages: 6093 publication data© 2017 Published in electronic format with permission by the Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 17 Aug 2017 CITATION INFORMATION Sayyid Suhail Ahmad, Wiktor Waldemar Weibull, Alejandro Escalona, and Robert James Brown, (2017), "Stack-related and nonstack-related mechanisms for the generation of low-frequency anomalies: Examples from Johan Sverdrup field, central North Sea," SEG Technical Program Expanded Abstracts : 2395-2399. https://doi.org/10.1190/segam2017-17739843.1 Plain-Language Summary Keywordsfractureslow frequencyspectralamplitudeattributesPDF DownloadLoading ...