Simultaneous sources: recent advances in marine acquisition and processing

Abstract

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. The use of simultaneous sources is now a commercial reality for marine data. There is, however, significant scope for development both in the acquisition design and the data processing. Conventional processing based on 'shot records' ceases to apply in the general case that shots are taken at arbitrary times, and many of the conventional constraints on the acquisition design can be relaxed when shots are allowed to interfere. The recorded data become a continuous stream for each sensor, and new processing algorithms are required to handle the generalized interference. This paper extends the current processing ideas used for the simple, marine simultaneous-source scenarios previously presented to the more general case, and illustrates the potential and the issues involved using simulated datasets for which the correct answer is known. The shot timing and sampling is, as might be expected, a critical factor in the survey design if processing is to be successful. Provided the survey is designed appropriately, it is shown that the use of simultaneous source technology can improve both acquisition efficiency and the quality of the final product.