Reservoir Evaluation and Development ›› 2020, Vol. 10 ›› Issue (5): 42-48.doi: 10.13809/j.cnki.cn32-1825/te.2020.05.006

• Methodological and Theory • Previous Articles     Next Articles

A fast computing method for rock electric parameters of Cole-Cole model in Jiaoshiba Zone

LIU Zhiying1,2(),ZHANG Baiqiao1,XU Wei2,LUO Bing1,LI Minghua1,LI Wei1   

  1. 1. Research Institute of Exploration and Development, Sinopec Jianghan Oilfield, Wuhan, Hubei 430223, China
    2. College of Geophysics and Petroleum Resources, Yangtze University, Wuhan, Hubei 430100, China
  • Received:2019-11-07 Online:2020-10-26 Published:2020-09-24

Abstract:

Calculation of 4 parameters, ρ0, m, τ and c, of Cole-Cole model by complex rock core resistivity data measured with multi-frequency is an important nonlinear optimization problem in rock core complex resistivity experiments. However, in Jiaoshiba Zone, a very small τ and c with big value range cause the difficulty of the convergence of optimization program. Therefore, the initial value determination and optimized iteration step have been studied. The improved program performances well on the speed of convergence, and avoids the calculation failure caused by out-range of the parameter τ. The study indicates that according to the maximum property and asymmetry property, the parameter τ can be obtained directly, and good iteration initial values of the rest 3 parameters can be obtained either. Meanwhile, by transforming the error function to be Tyler series, the optimized iteration step can be obtained and the convergence speed can be upgraded significantly.

Key words: Cole-Cole model, least square method, gradient descent algorithm, iteration initial value estimation, optimized iteration step, shale in Longmaxi Formation

CLC Number: 

  • P315.69