Schlumberger

Technical Paper: The Fidelity of 3D Wavefield Reconstruction From a Four-Component Marine Streamer and its Implications for Time-Lapse Seismic Measurements

Society: SEG
Paper Number: 2012-908
Presentation Date: 2012
 

Abstract

It is well documented in time-lapse (or 4D) seismic literature that the non-repeatability of the acquisition geometry is the single-most important factor contributing to a residual noise floor for the 4D seismic signal from the reservoir. To compensate for imperfect receiver repositioning, wavefield regularization techniques can be applied to allow for wavefield matching common to both vintage surveys. Typically, a trade-off is made between reducing the receiver positioning mismatch and the imperfections introduced by wavefield spatial aliasing due to acquisition geometry and geology. Wavefield reconstruction techniques are at the core of this paper, however with a different underlying basis than that for conventional approaches. Through use of towed 3D fourcomponent (4C) marine seismic streamers and the application of matching pursuit interpolation processing techniques, a 3D reconstructed and deghosted pressure wavefield can be obtained on a densely sampled grid that permits wavefield matching to vintage positions in an unprecedented, effective way, as recently demonstrated by Özbek et al. (2010). This paper focuses on quantifying the fidelity of the wavefield reconstruction and discusses the implications of such 4C acquisition and processing on 4D seismic measurements.

Based on data analysis from an experimental 3D-4C test, the findings from the assessment presented in this paper are three-fold: firstly, the pressure recordings of the new 3D-4C acquisition system are found to be fully comparable to that of the existing production, hydrophone-only counterpart, used as a benchmark. Hence, established 4D characteristics for the benchmark system remain valid for the pressure recording of the 4C system. Secondly, the uniformly sampled pressure cube, output by the multicomponent seismic wavefield reconstruction, compares favorably with the recorded and uninterpolated pressure benchmark, contributing to establishing the integrity of the reconstructed wavefield. Thirdly, the 3D-4C-enabled wavefield reconstruction is found to furnish superior performance as compared to a hydrophone-only state-of-the-art interpolator, in particular, in areas with significant cable feathering. Overall, we find this 4C seismic acquisition and processing approach to offer the prospect of significantly reducing the effects of receiver mispositioning, leading to marked improvements of the 4D results. The source mispositioning becomes the critical limiting factor on the acquisition side to ensure high seismic repeatability - a limitation, however, that can be addressed effectively through available source steering technology.

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