A three-dimensional finite difference code for the modeling of sonic logging tools
作者:
Yong-Hua Chen,
Weng Cho Chew,
Qing-Huo Liu,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1998)
卷期:
Volume 103,
issue 2
页码: 702-712
ISSN:0001-4966
年代: 1998
DOI:10.1121/1.421230
出版商: Acoustical Society of America
关键词: SONIC LOGGING;SIMULATION;TOOLS;FINITE DIFFERENCE METHOD;WELL DRILLING;COMPUTER CODES;WAVE PROPAGATION;BOREHOLES;SLEEVES;SCATTERING
数据来源: AIP
摘要:
This paper presents a numerical program for the simulation of elastic wave propagation and scattering in three-dimensional (3-D) cylindrical coordinates based on the first-order velocity-stress finite-difference scheme on staggered grids. Both Liao’s and Lindman’s absorbing boundary conditions are implemented for the exterior boundaries to efficiently truncate the computation domain for elongated 3-D well logging problems. Symmetric and anti-symmetric boundaries in azimuthal and axial directions are also implemented in the code to further reduce the size of the problem. Included for the first time with this code are very large and complex geometrical structures such as the whole slotted sleeve housing of a sonic well-logging tool which typically involves hundreds of millions of unknowns. The calculation for such a large problem only takes a couple of days on a four-processor SGI Power Challenge machine. Different types of slotted sleeve models are studied for sonic logging tools. Simulation results show that different slotted sleeves vary widely in delaying and attenuating the pipe waves which travel along the tool housing. A new slotted sleeve structure with three horizontal slot sections for every vertical slot period is proposed for better performance. A dipole source is found to produce much cleaner waveforms than a monopole source.
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