Seismic AVO statistical inversion incorporating poroelasticity
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ORIGINAL PAPER
Seismic AVO statistical inversion incorporating poroelasticity Kun Li1,2 · Xing‑Yao Yin1,2 · Zhao‑Yun Zong1,2 · Hai‑Kun Lin1,2 Received: 8 January 2020 © The Author(s) 2020
Abstract Seismic amplitude variation with offset (AVO) inversion is an important approach for quantitative prediction of rock elasticity, lithology and fluid properties. With Biot–Gassmann’s poroelasticity, an improved statistical AVO inversion approach is proposed. To distinguish the influence of rock porosity and pore fluid modulus on AVO reflection coefficients, the AVO equation of reflection coefficients parameterized by porosity, rock-matrix moduli, density and fluid modulus is initially derived from Gassmann equation and critical porosity model. From the analysis of the influences of model parameters on the proposed AVO equation, rock porosity has the greatest influences, followed by rock-matrix moduli and density, and fluid modulus has the least influences among these model parameters. Furthermore, a statistical AVO stepwise inversion method is implemented to the simultaneous estimation of rock porosity, rock-matrix modulus, density and fluid modulus. Besides, the Laplace probability model and differential evolution, Markov chain Monte Carlo algorithm is utilized for the stochastic simulation within Bayesian framework. Models and field data examples demonstrate that the simultaneous optimizations of multiple Markov chains can achieve the efficient simulation of the posterior probability density distribution of model parameters, which is helpful for the uncertainty analysis of the inversion and sets a theoretical fundament for reservoir characterization and fluid discrimination. Keywords Poroelasticity · AVO inversion · Statistical inversion · Bayesian inference · Seismic fluid discrimination
1 Introduction Subsurface rock is composed of solid mineral matrix, dry pores/fractures and various fluid mixtures and set foundation for geophysical interpretation (Biot 1956; Han and Batzle 2004; Russell et al. 2011; Yin et al. 2015; Ding et al. 2019a; Li et al. 2020). Biot–Gassmann’s theory describes the propagation of elastic wave in saturated porous media and establishes the quantitative relationship between rock Edited by Jie Hao * Zhao‑Yun Zong [email protected] Kun Li [email protected] Xing‑Yao Yin [email protected] 1
School of Geosciences, China University of Petroleum (East China), Qingdao 266580, Shandong, China
Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, Shandong, China
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modulus and seismic wave velocity, which is the physical basis of seismic hydrocarbon discrimination (Gassmann 1951; Biot 1956; Ding et al. 2019b; Liu et al. 2020; Li et al. 2020). Prestack seismic AVO (amplitude variation with offset) inversion is an important approach for quantitative characterization of rock elasticity, physical properties, lithology and fluid properties (Smith and Gidlow 1987; Rutherford and Williams 1989; Goodway et al. 1997; Gray et al. 1999;
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