LAUSR

Abstract Seismic waveform propagation could be significantly affected by heterogeneities in the near surface zone (0 m–500 m depth). As a result, it is important to obtain as much near surface information as possible. Seismic attenuation, characterized by Q P and Q S factors, may affect seismic waveform in both phase and amplitude; however, it is rarely estimated and applied to the near surface zone for seismic data processing. Applying a 1D elastic full waveform modelling program, we demonstrate that such effects cannot be overlooked in the waveform computation if the value of the Q factor is lower than approximately 100. Further, we develop a pseudo 2D elastic waveform inversion method in the common midpoint (CMP) domain that jointly inverts early arrivals for Q P and surface waves for Q S . In this method, although the forward problem is in 1D, by applying 2D model regularization, we obtain 2D Q P and Q S models through simultaneous inversion. A cross-gradient constraint between the Q P and Qs models is applied to ensure structural consistency of the 2D inversion results. We present synthetic examples and a real case study from an oil field in China.