Simultaneous sources: recent advances in marine acquisition and processing

Until recently, seismic data acquisition has been fundamentally limited by the requirement that the delay time between one shot and the next be sufficient to avoid significant contamination of data from one shot with energy from another. Acquisition with simultaneous sources drops this requirement, and therefore provides potential for enormous improvements in acquisition rates and source sampling. In order to realize this potential however, the way we acquire and process data must change.Although simultaneous-source technology is already a commercial reality for both land and marine acquisition, there is considerable scope for further optimization, especially in the marine case. In this work, I address the specific issue of relaxing the constraint that sources fire near-synchronously, such that the options for survey design in particular are greatly increased. I show that separation into individual shot records is possible even with arbitrary shot firing times, provided those times have some randomness to them. I address the major issue of removing strong interference from deep data, and show how this can be significantly improved by supplying prior information about the expected general decay of amplitude with time. Simulated simultaneous- source data, for which the correct answer is known, are used to illustrate the method.