3D Seismic Among Icebergs in a Volcanic Provenance – A Successful Project Offshore Greenland Using Dual-sensor Streamers

In the summer of 2009, PGS acquired two 3D seismic surveys in Arctic waters offshore West Greenland for Husky Energy. Dual-sensor GeoStreamer technology was used, and the project seemed ideal to benefit from its apparent advantages. Challenges included a short 3 – 4 month ice-free season, avoiding icebergs during acquisition, a hard water-bottom notorious for strong multiple energy, and volcanic flows with associated dikes and sills within and overlying prospect objectives. Since the dual-sensor streamer technology allows for deep-towed source and receivers without compromising higher frequencies in the amplitude spectrum, operating windows in rough seas were increased. The increased energy recorded in the amplitude spectrum lower than 20 Hz was found more appropriate to penetrate primary energy through attenuative volcanic rocks than what conventional tow depths have achieved historically. Project planning was critical to the success of the surveys. Ray tracing was conducted to ensure the survey outline provided an adequate migration aperture to fully image complex structures. 3D survey design analysis ensured that the most suitable parameters were being prescribed, particularly specific to sub-basalt imaging. Special considerations in operations included radar imaging for iceberg detection, and methodical infill analysis tailored to the subsurface geology.