| Title | Hydrocarbon indicators on seismic data: Insights from poroviscoelastic modeling, amplitude, and frequency variation with offsets from the Drake Point gas field, Western Arctic Islands, Canada |
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| Author | Duchesne, M J ;
Giroux, B; Hu, K |
| Source | Interpretation vol. 2, issue 4, 2014 p. SP45-SP59, https://doi.org/10.1190/INT-2014-0018.1 |
| Year | 2014 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130420 |
| Publisher | Society of Exploration Geophysicists |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Nunavut |
| NTS | 79B/08 |
| Area | Melville Island; Drake Point |
| Lat/Long WENS | -109.0000 -108.0000 76.5000 76.2500 |
| Subjects | geophysics; fossil fuels; hydrocarbons; gas; gas fields; seismic data; seismic surveys; seismic interpretations; modelling; analytical methods |
| Program | GEM: Geo-mapping for Energy and Minerals Geomapping for Energy & Minerals (GEM) - Geo-mapping Frontiers |
| Released | 2014 11 01 |
| Abstract | (unpublished)
The evaluation of drilling prospects is frequently based on seismic amplitude anomalies. To decipher "true" seismic prospects from "false" ones, we used poroviscoelastic (PVE)
models, as opposed to other formalisms such as acoustic, elastic, viscoelastic, and poroelastic models, that provided a solution that takes into account solid and fluid attenuation mechanisms separately to model the earth's response to the
propagation of a seismic wavefield. Here, a PVE impedance modeling scheme was tested using seismic and well-log data collected on a conventional gas reservoir in the Canadian Arctic. Comparisons between seismic-to-well ties achieved using acoustic
and PVE media indicated that the latter provided more realistic synthetic seismograms. Although prestack analysis revealed that the present lithological context was of class I amplitude variation with offset (AVO), the seismic signature observed was
of class III AVO. Consequently, the increase in amplitude with offset was interpreted to be induced not by a lithological change (i.e., shale to sand) combined with a gas-charged interval, but rather by an increase in porosity within the sandstone
reservoir itself where the gas has accumulated. Frequency variation with offset analysis using spectral decomposition, image low-frequency shadows on the far offsets attributed to the gas accumulation that were correlative with the AVO anomaly. This
highlighted the importance of far offsets in anomalous amplitude and frequency events attributed to the occurrence of gas reservoirs observed on stacked data and that these events can be missed if seismic hydrocarbon indicators were solely
investigated on stacked data. Finally, the method of analysis emphasized the importance of combining indirect arguments coming from the observation of prestack and stacked seismic data in the time and frequency domains for reducing risk to an
acceptable level before a prospect can be drilled. |
| Summary | (Plain Language Summary, not published)
The evaluation of drilling prospects in oil and gas exploration is frequently based on seismic amplitude anomalies. For deciphering true from false
seismic amplitude prospects forward modeling is often used. Here a methodological workflow seismic forward modeling that takes into account solid and fluid attenuation mechanisms separately to model the Earth's response to the propagation of a
seismic wavefront is tested. The workflow is developed using seismic and well log data collected on a conventional gas reservoir in the Canadian Arctic. Comparisons between field data and the seismic show it adequately reproduces the response of
geological media to seismic wave propagation. Finally the method proved to be successful for detecting hydrocarbon accumulations. |
| GEOSCAN ID | 293527 |
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