Applications of shear waves in modern seismic technology: Overview and examples

Seismic reflection, with its compressional P-wave technology, has significantly contributed to the discovery of oil reserves in basins worldwide. With the increasing complexity of deep formations being targeted in the oil industry nowadays, an additional source of information to assist and complement P-wave became necessary. Shear wave, the common companion of P-wave, was found to be an ideal candidate for this key role. Indeed, the improved understanding of S-waves has led to the extraction of more key information about subsurface and to the discrimination of various lithologies and fluids with lower risk and reduced uncertainty. Numerous approximations have been proposed in literature to extract shear-wave information from P-waves. The analysis of these approximations demonstrates that S-waves have been strongly involved in many successful hydrocarbon discoveries that were previously attributed strictly to P-waves. Bright-spot technology, amplitude variation with offset (AVO) methods, and AVO inversions have relied significantly on S-waves in the interpretation of the anomalous behaviors of hydrocarbon-saturated formations. This has resulted in an increased attention to shear-wave technology. As a result, tremendous advances have been reported in S-wave acquisition, processing, and interpretation. In this paper, we give a historical overview about S-wave technology. This is followed by fundamental concepts behind the S-wave technology and its applications for hydrocarbon detection and reservoir characterization. Recent examples from world basins are highlighted. To conclude, the enhanced understanding of S-wave differences with P-wave allow geophysicists to successfully handle and integrate S-wave data along with conventional P-wave data in most modern reservoir characterization workflows. With the recent advances in multicomponent seismology, successful experiments demonstrated that shear wave can be extracted from P-wave data that have been recorded using conventional single component geophones. That would indeed encourage reprocessing legacy P-wave seismic surveys to retrieve shear wave information in many world regions where S-wave could not be considered.