Seeing Through the Noise: Seismic Survey Design in the Caspian Sea

This paper uses results of seismic field trials to assess the ability of broadband towed streamer and high density OB data to improve imaging in the Caspian Sea.

It is demonstrated that current OB data, despite providing sufficient sampling for primary data, is limited by slow noise trains. These are aliased above ∼30Hz in the most densely sampled domain (receiver gathers). By increasing shot density this noise is fully sampled and can be removed. It is therefore shown that a high density OB survey increases usable bandwidth as well as improving image quality.

Deep tow broadband seismic is shown to have some anticipated advantages, such as improved low frequency signal, but the improvements are shown to be more marginal than hoped. However, this could have been limited by the equipment in use rather than the survey design.

By comparing various forms of towed streamer and OB data acquired simultaneously from the same sources it is possible to understand limitations of current data, and to optimise the design of future 3D surveys.