Effect of borehole stress concentration on compressional wave velocity measurements
Name
Fang_etal_Effect_of_borehole_stress_concentration_on_compressional_wave_velocity_measurement.pdf
Size
681.96 KB
Format
Adobe PDF
Checksum (MD5)
c972968c20791c060a5f0e6c7feb0947
Author(s)
Fang, Xinding
Fehler, Michael
Cheng, Arthur
Date Issued
2013
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2013-11
Abstract
Formation elastic properties near a borehole may be altered from their original state due to the stress concentration around the borehole. This could lead to a biased estimation of formation elastic properties measured from sonic logging data. To study the effect of stress concentration around a borehole on sonic logging, we first use an iterative approach, which combines a rock physics model and a finite-element method, to calculate the stress-dependent elastic properties of the rock around a borehole when it is subjected to an anisotropic stress loading. Then we use the anisotropic elastic model obtained from the first step and a finite-difference method to simulate the acoustic response in a borehole. Our numerical results are consistent with published laboratory measurements of the azimuthal velocity variations caused by borehole stress concentration. Both numerical and experimental results show that the variation of P-wave velocity versus azimuth has broad maxima and cusped minima, which is different from the presumed cosine behavior. This is caused by the preference of the wavefield to propagate through a higher velocity region.
Subjects
Logging
Modeling
Persistent DSpace Link
