Geologies with complex, rough or high contrast sediments such as salt bodies or chalks are often difficult to image due to poor seismic signal penetration. In addition, poor signal to noise ratios often cause the latest model building algorithms such as Full Waveform Inversion (FWI) to perform inefficiently and less effectively in a phenomena commonly referred to as cycle skipping. As a result, velocity models and their resulting seismic images do not often paint as accurate a representation of the subsurface as necessary to identify prospects, derisk and prioritize them or optimize well placement.
However, extensive research using synthetic data has proven that highly accurate velocity models may be achieved for complex geologies simply by using the inputs from the lowest frequencies, <4Hz. This is because lower frequencies are able to penetrate rough or high contrast boundaries more effectively, thereby improving the signal to noise ratio in the data.
ION’s new Gemini™ Extended Frequency Source (EFS) technology is a broadband seismic source technology that is able to generate the <4Hz frequencies required to image in complex geologies where penetration of low frequencies is key. The Gemini source is unique as it emits a broader spectrum of frequencies (2 – 80 Hz or higher) than conventional sources or other purpose built low frequency sources. These characteristics allow it to offer an alternative to conventional sources for more efficient seismic acquisition. In addition, the Gemini source offers a more environmentally friendly source solution that reduces the impact to marine life through its lower amplitudes at higher frequencies.
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Left Image: Conventional OBS source with 0-0-4-5 Hz filter with 40-45 km offsets.
Right Image: Gemini Extended Frequency Source with 0-0-4-5 Hz filter with 40-45 km offsets.