Towing a seismic source over the seismic spread

What initially started as an imaging challenge and a series of possible solutions from Lundin's geophysicists, is now transformed into a new improved technology for seismic data imaging; TopSeis. This new solution provides a significantly better image of the subsurface and hence overcomes the inability of previous methods to image shallow geological features, such as faults, gas pockets, channels and stratigraphic pinch-outs. By overcoming these shortcomings, TopSeis enables exploration and development teams to make critical investment decisions on the basis of high-quality data delivered at a lower cost compared to other seismic acquisition techniques. TopSeis is a method involving two seismic vessels operating in tandem. By placing the signal sources of one of the vessels directly over the cables instead of in front of them, this yields more signal reflection than with conventional seismic acquisition. This allows us to record up to fifteen times as much of the reflected energy from the subsurface. To achieve this, the streamers must be towed at a sufficient depth in the water so that the vessel with the sources can sail over them without interfering with the cables, an operation previously considered impossible. TopSeis provides a detailed and quantitative depiction of the reservoirs, and is particularly well-suited for shallow to intermediate oil and gas fields such as those in the Barents Sea. This will reduce the risk associated with drilling, and improve the chance of finding oil and gas. We encourage you to view the video published on TopSeis in March 2018 that describes the technology: https://www.youtube.com/watch?v=M7Uiv69O4iE The latest development in the project has focused on towing the sources wider, as well as going from three to five and six+ simultaneous sources. This was realized for the first time in October 2018 during a small survey in the North Sea, and then implemented in a large scale (5000km2) survey in the Barents Sea in 2019. With this new technique, we multiply the trace density, which enables very accurate and sharp depiction of the subsurface. Compared with conventional or OBN / OBC acquisitions, one can say that our new TopSeis system is like moving from old-fashioned TVs to 4K. In conclusion, TopSeis works, and is a commercial success on the Norwegian Continental shelf.

The goal of the TopSeis project was to develop a "next generation" marine seismic acquisition system to provide improved subsurface imaging. This was done by developing an acquisition system where multiple small, rapidly firing and wide-towed sources were deployed over a streamer spread towed by a separate vessel. In addition we had to develop the accompanying processing solutions to take full advantage of the recorded data. These goals were all achieved by the project. Commercially, at the time of writing, two large TopSeis surveys have been acquired in the Barents Sea. The technology it accepted in the industry, and we there is a clear potential for TopSeis to grow a significant market share in the years to come.