Reduction of Acquisition Time Sharing in the North Sea by Seismic-Interference Attenuation

In 2003, Seismic Interference (SI) was recorded during the simultaneous acquisition of BP’s Valhall OBC data and towed streamer data in Quad 30 (Figure 1). BP and Veritas jointly initiated a project to investigate SI attenuation methods, in order to define new noise thresholds for acquisition in the presence of SI and so reduce the need for time sharing. A range of standard and non-standard processing algorithms and flows were evaluated on the contaminated data. It was concluded that the recorded SI could be successfully removed pre-stack from both datasets with accurate signal amplitude preservation. This extends the findings of Jack and Lancaster 1989 and Lynn et al 1987. In 2004 streamer test data were recorded containing SI from the Valhall source. These were used to build an interference noise library to model SI arrivals from a range of bearings and strengths. The results of subsequent processing and analysis enabled both companies to agree to acquire surveys in this area during 2005 with reduced time-sharing.