A standard quantitative calibration procedure for marine seismic sources

Abstract

Marine source evaluation has traditionally been a subjective and qualitative study. This is particularly true in the case of source spectral characteristics. As a result, source evaluation, development, and array design based on seismic energy over a specified frequency band have been impossible. Further, the transient nature of source wavelets lends itseft to energy analysis rather than the traditional relative power analysis. The methodology required to achieve a calibrated quantitative estimate of marine seismic source energy is detailed here. The procedure involves two steps. First, a calibrated high‐fidelity measurement of the source signature is required; and second, an analysis of the signatures by a suite of computer algorithms designed to extract quantified measures of amplitude and energy is necessary. Results of the analysis include a time‐domain signature calibrated in American National Standards Institute (ANSI) units of pressure and a frequency domain spectrum calibrated in ANSI units of energy flux. These results provide figures of merit for evaluation of individual source characteristics (e.g., energy flux over seismic bandwidth, and total source energy). Additionally, the results provide data for a quantitative comparison of any two or more sources. Illustrative examples of source studies are included.