Below is an example of a video we created to display the time slice of a processed 3D reflection seismic data through time. The data had been processed using our partner’s proprietary PhaseDecomp(TM). Click on the image below to start the video. You can maximize the video by clicking the arrow symbol on the top right side of the video black background.
The data is a 3D reflection seismic from F3 block in the Dutch North Sea. The data set used is provided by dGB Earth Sciences for use with the OpendTect software. This data set demonstrates excellent examples of Direct Hydrocarbon Indicators (DHIs), gas chimneys, and stratigraphic features.
Below is the interpreted seismic vertical section revealing some important features. In the very shallow area, we observe acoustic blankings and enhanced reflections. The area exhibits significant bright reflections that are very flat in nature, contrasting with the structural trend of the surrounding rocks.
The subsurface expressions such as shallow bright spots and flat spots suggest a trapping of gas in reservoir sands. Bright spots are known to be the best DHI on seismic data. It is a high amplitude anomaly caused by the strong decrease in acoustic impedance at the top of a hydrocarbon reservoir. The amplitude is much stronger with gas than with oil reservoir.
Fig.1 A shallow bright spot overlying a flat spot which corresponds to the gas-water-contact. This indicates an effective of structural trapping of shallow gas in an unconsolidated clastic environmet.