Rock physics inversion based on an optimized MCMC method
Zhang Jia-Jia, Li Hong-Bing?, Zhang Guang-Zhi, Gu Yi-Peng, and Liu Zhuo-Fan
1. School of Geosciences, China University of Petroleum (East China), Qingdao 266580, China
2. Shandong Provincial Key Laboratory of Deep Oil and Gas, Qingdao 266580, China
3. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
Abstract Rock physics inversion is to use seismic elastic properties of underground strata for predicting reservoir petrophysical parameters. The Markov chain Monte Carlo (MCMC) algorithm is commonly used to solve rock physics inverse problems. However, all the parameters to be inverted are iterated simultaneously in the conventional MCMC algorithm. What is obtained is an optimal solution of combining the petrophysical parameters with being inverted. This study introduces the alternating direction (AD) method into the MCMC algorithm (i.e. the optimized MCMC algorithm) to ensure that each petrophysical parameter can get the optimal solution and improve the convergence of the inversion. Firstly, the Gassmann equations and Xu–White model are used to model shaly sandstone, and the theoretical relationship between seismic elastic properties and reservoir petrophysical parameters is established. Then, in the framework of Bayesian theory, the optimized MCMC algorithm is used to generate a Markov chain to obtain the optimal solution of each physical parameter to be inverted and obtain the maximum posterior density of the physical parameter. The proposed method is applied to actual logging and seismic data and the results show that the method can obtain more accurate porosity, saturation, and clay volume.
Fund: This work was supported by the National Natural Science Foundation of China (No. 42174146), CNPC major forwardlooking basic science and technology projects (No. 2021DJ0204).
Corresponding Authors: Li Hong-Bing (E-mail: hbingli@petrochina.com.cn).
E-mail: hbingli@petrochina.com.cn
About author: graduated from Ocean University of China with a bachelor’s degree in geoscience information in 2007, graduated from Ocean University of China with a master’s degree in earth exploration and information technology in 2010, and graduated from Research Institute of Petroleum Exploration and Development, PetroChina, with a doctor’s degree in earth exploration and information technology in 2013. Currently, he is an associate professor at China University of Petroleum (East China). His main research interests are seismic rock physics theory and experiments. Corresponding author: Li Hongbin
Cite this article:
ZHANG Jia-Jia,LI Hong-Bing,ZHANG Guang-Zhi et al. Rock physics inversion based on an optimized MCMC method[J]. APPLIED GEOPHYSICS, 2021, 18(3): 288-298.
2021, Vol. 18 
