EPC 2002 Tunis May 7-11, 2002

Analysis of the Slip Sweep Technique J.MEUNIER, J.J.POSTEL, A.DEPEYRAS, E.GILLOT, M.HAYET,  CGG, 1 rue Léon Migaux   91301 Massy (France)   In order to prepare a 2D slip-sweep simulation experiment, a preliminary analysis was conducted using synthetic data. Various types of noise were isolated and the corresponding data contamination analysed. Signal-to-noise ratio maps were generated for various slip-sweep configurations. The same analyses were conducted on the actual data after slip sweep simulation, correlation and standard processing. This study has allowed us to classify various type of noise and to describe the effects. Despite inherent limitations, namely, inexact analysis of ambient and uncorrelated noise, this simulation presents the unique advantage of providing a reliable signal-to-noise ratio estimate. Since data contamination by both ambient and uncorrelated noise would be smaller in an actual 3D slip-sweep recording, these ratios are a low estimate of the actual case. In this example, we found a ratio larger than 20 dB for a slip time of 10 s everywhere signal can be recognized in the data. A slip time of 5 s removes less than 5 dB from this ratio. This analysis can help define accurate slip-sweep parameters, which optimise productivity versus S/N ratio on stacked data.