1D viscoelastic waveform inversion for Q structures from the surface seismic and zero-offset VSP data

摘要

Wave attenuation is an important physical property of hydrocarbon- bearing sediments that is rarely taken into account in site characterization with seismic data. We present a 1D viscoelastic waveform inversion scheme for determining the quality factor Q from the normal-incidence surface seismic and zero-offset vertical seismic profile VSP data simultaneously. The joint inversion problem is solved by the damped least-squares method, and the inversion result is successful using synthetic data. The effects of initial model thickness,Q value, and the existence of noise were studied through a synthetic example. By extracting all of the information contained in the waveforms, the waveform inversion of the seismic reflection and transmission data becomes a powerful tool for estimating Q. For a more comprehensive image of Q, the tomographic inversion of Q is applied to the walkaway VSP and prestack surface seismic data, using the waveform inversion result as the initial model. Results from applying the method to a real seismic line and zero-offset VSP data from the Nanyang oilfield, central China, indicate that Q from the tomographic inversion of reflection and transmission data contains useful information on medium properties, which can aid in reservoir appraisal.