TopSeis™ is a next-generation marine towed-streamer acquisition solution, delivering a step-change in imaging for shallow to intermediate depth targets by providing massively increased near-offset coverage from a split spread with zero offsets. It is the latest addition to our broadband portfolio and is the most recent outcome from over eight years of technical collaboration between CGG and Lundin Norway AS, with additional funding from the Norway Research Council. The first full scale commercial survey has recently been completed for Lundin in the Barents Sea.
TopSeis is a tailored solution, specifically designed to improve imaging of shallow and intermediate-depth targets by overcoming the lack of near-offset fold inherent in towed-streamer seismic. TopSeis achieves this by using an innovative source-over-spread acquisition configuration and proprietary processing algorithms.
Based on an original idea from Lundin, TopSeis has been developed over the last two years by a multi-disciplinary team of CGG and Sercel Equipment, Marine Acquisition and Geoscience experts, using synthetic data and field trials to derive optimum configurations for specific targets and to develop methods to deploy these configurations safely. It capitalizes on CGG’s long-standing broadband capabilities, including deep-tow experience from acquiring over 350,000 km² of BroadSeis™, deployment of our broadband source (BroadSource™) and our recognized Subsurface Imaging excellence.
The significantly increased sampling of near and zero offsets delivered by TopSeis should result in improved AVO curve fitting as well as direct recording of the intercept, R0. This will increase the accuracy and reliability of the AVO results.
For a synthetic model, based on the Wisting field in the Barents Sea, and developed in collaboration with OMV, the TopSeis response to the model can be seen to deliver a much better correlation for the AVO intercept and gradient than the conventional response. The TopSeis synthetic seismic also shows much better correlation with the model, with sharper wavelets, less noise and a clearer oil water contact.
A 15km x 3km 3D trial was carried out over the Frigg-Gamma field in the North Sea. The multi-client BroadSeis data was used as the reference. The TopSeis data shows considerable improvement over the reference data, especially where illuminated by the outer streamers only. Initial results from the proprietary commercial survey in the Barents Sea are also delivering outstanding improvements.
The improvement continues deeper in the section, as seen in the comparison below:
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An innovative source-over-spread solution for imaging shallow reservoirs.