Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs
Polarizations of split shear waves and flexural borehole waves are most commonly estimated from four-component data using the rotation technique of Alford (1986). This method is limited to the case of the two polarizations being orthogonal to each other. We present a method that is able to handle...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Technical Report |
| Published: |
Massachusetts Institute of Technology. Earth Resources Laboratory
2012
|
| Online Access: | http://hdl.handle.net/1721.1/75318 |
| _version_ | 1826199984635117568 |
|---|---|
| author | Nolte, Bertram Cheng, Arthur C. H. |
| author2 | Massachusetts Institute of Technology. Earth Resources Laboratory |
| author_facet | Massachusetts Institute of Technology. Earth Resources Laboratory Nolte, Bertram Cheng, Arthur C. H. |
| author_sort | Nolte, Bertram |
| collection | MIT |
| description | Polarizations of split shear waves and flexural borehole waves are most commonly estimated from four-component data using the rotation technique of Alford (1986). This
method is limited to the case of the two polarizations being orthogonal to each other.
We present a method that is able to handle the case of nonorthogonally polarized waves
and, moreover, is computationally more efficient than Alford's technique. Our method
is based on the eigenvalue decomposition of an asymmetric matrix and a least-squares
minimization of its off-diagonal components. In the case of orthogonally polarized waves,
our method will yield exactly the same results as the Alford rotation. We apply our
method to a cross-dipole shear-wave logging data set from the Powder River Basin in
Wyoming and find that independently rotated source-receiver sets are very consistent
with each other in anisotropic sections. After the rotation we compare two methods
for estimating the phase velocities of fast and slow waves-a semblance method and
homomorphic processing (Ellefsen et al., 1993). We find homomorphic processing to be
more reliable due to the dispersive nature of flexural waves. |
| first_indexed | 2024-09-23T11:28:55Z |
| format | Technical Report |
| id | mit-1721.1/75318 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T11:28:55Z |
| publishDate | 2012 |
| publisher | Massachusetts Institute of Technology. Earth Resources Laboratory |
| record_format | dspace |
| spelling | mit-1721.1/753182019-04-12T20:32:21Z Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs Nolte, Bertram Cheng, Arthur C. H. Massachusetts Institute of Technology. Earth Resources Laboratory Nolte, Bertram Cheng, Arthur C. H. Polarizations of split shear waves and flexural borehole waves are most commonly estimated from four-component data using the rotation technique of Alford (1986). This method is limited to the case of the two polarizations being orthogonal to each other. We present a method that is able to handle the case of nonorthogonally polarized waves and, moreover, is computationally more efficient than Alford's technique. Our method is based on the eigenvalue decomposition of an asymmetric matrix and a least-squares minimization of its off-diagonal components. In the case of orthogonally polarized waves, our method will yield exactly the same results as the Alford rotation. We apply our method to a cross-dipole shear-wave logging data set from the Powder River Basin in Wyoming and find that independently rotated source-receiver sets are very consistent with each other in anisotropic sections. After the rotation we compare two methods for estimating the phase velocities of fast and slow waves-a semblance method and homomorphic processing (Ellefsen et al., 1993). We find homomorphic processing to be more reliable due to the dispersive nature of flexural waves. Massachusetts Institute of Technology. Borehole Acoustics and Logging Consortium United States. Dept. of Energy (Contract DE-FG02-86ER13636) 2012-12-10T17:47:20Z 2012-12-10T17:47:20Z 1996 Technical Report http://hdl.handle.net/1721.1/75318 Earth Resources Laboratory Industry Consortia Annual Report;1996-02 application/pdf Massachusetts Institute of Technology. Earth Resources Laboratory |
| spellingShingle | Nolte, Bertram Cheng, Arthur C. H. Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title | Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title_full | Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title_fullStr | Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title_full_unstemmed | Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title_short | Estimation Of Nonorthogonal Shear Wave Polarizations And Shear Wave Velocities From Four-Component Dipole Logs |
| title_sort | estimation of nonorthogonal shear wave polarizations and shear wave velocities from four component dipole logs |
| url | http://hdl.handle.net/1721.1/75318 |
| work_keys_str_mv | AT noltebertram estimationofnonorthogonalshearwavepolarizationsandshearwavevelocitiesfromfourcomponentdipolelogs AT chengarthurch estimationofnonorthogonalshearwavepolarizationsandshearwavevelocitiesfromfourcomponentdipolelogs |