Stepwise inversion method for determining anisotropy parameters in a horizontal transversely isotropic formation
Song Yun-Hong, Chen Hao, and Wang Xiu-Ming
1. State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing, 100190, China.
2. University of Chinese Academy of Sciences, Beijing, 100049, China.
3. Beijing Engineering Research Center of Sea Deep Drilling and Exploration, Institute of Acoustics, Chinese Academy of Sciences, Beijing, 100190, China.
Abstract The anisotropy of a geologic formation can reflect the direction of fractures and ground stress, which is an important metric that guides the exploration and development of oil and gas reservoirs. Cross-dipole acoustic logging is the main method used to detect anisotropy with borehole geophysics. In this paper, a stepwise inversion method for three anisotropy parameters in a horizontal transversely isotropic (HTI) formation is proposed, which turns one 3D operation of simultaneous inversion into three 1D operations. The scheme’s stability and reliability were tested by numerically simulated data using a finite-difference method, and by field logging data. The inversion results of the simulated data show that the stepwise inversion method can stably obtain the fast shear azimuth and the anisotropy parameters in both fast and slow formations with strong and weak anisotropy, and it performed well even with noisy data. In particular, the results of the fast shear azimuth inversion were very stable and reliable. The inversion results of field logging data were consistent with those given by existing commercial software, which used simultaneous inversion, for both fast and slow formations. Where large difference was observed between our stepwise method and the commercial software, our analysis suggests that the fast shear azimuth of our inversion was more reasonable, which reinforces its superior performance and practicality.
This work was supported by the National Natural Science Foundation of China (Grant Nos.: 11574347, 11774373,11734017 and 91630309 and the PetroChina Innovation Foundation) (No.: 2016D-5007-0304).
About author: Song Yun-Hong Ph.D. study at University of Chinese Academy of Sciences. Her main research directions are new forward and inversion methods of acoustic logging Email: songyh323@163.com. ?Corresponding author: Chen Hao, researcher. His main research direction is new logging methods and petrophysics. Email: chh@mail.ioa.ac.cn.
Cite this article:
. Stepwise inversion method for determining anisotropy parameters in a horizontal transversely isotropic formation[J]. APPLIED GEOPHYSICS, 2019, 16(2): 246-255.
2019, Vol. 16 
