Multichannel Elastic Impedance Inversion for Elastic Parameters

Abstract

Summary Petrophysical description of reservoirs requires proper knowledge of the elastic parameters which can be retrieved from pre-stack seismic data using the concept of the elastic impedance (EI).We propose an inversion algorithm which recovers the elastic parameters from pre-stack seismic data in two sequential steps. In the first step, using the multichannel blind seismic inversion method high-resolution blocky EI models are obtained directly from partial angle-stacks. Each angle-stack is inverted independently in a multichannel form without prior knowledge of the corresponding wavelet. The wavelet and EI model are simultaneously estimated in an alternating manner. Beginning with an initial wavelet, the data are inverted for a blocky EI model using an efficient total-variation (TV) regularization. The resulting EI is then used to update the wavelet. This loop is repeated until we arrive at the most blocky model describing the data. The second step involves inversion of the resulting EI models for elastic parameters. Mathematically, the EIs are linearly described by the elastic parameters in the logarithm domain. Consequently, these parameters are determined by a linear least squares method. The performance of the proposed inversion method is tested using synthetic and real data.