Interpretation of shear wave birefringence in P to S converted waves data using the propagator matrix method

We present an original method for estimating local shear wave birefringence properties for 3D surface P to S converted waves. To accomplish this we approach the problem using reverse VSP (RVSP). The method works in the pre-stack domain and uses the P waves converted to S as shear wave sources. We solve the transmission problem using the propagator matrix method. The importance of this method is that it does not require information about layering above the zone of interest and is accurate for estimating the anisotropy parameters. The method involves solving a non-linear problem in the frequency domain where Simulated Annealing is used as the global minimization technique. The procedure allows estimation of the propagator matrix related to the target zone, assuming plane wave propagation allows its diagonalization by pure rotations. This matrix diagonalization ends up with an estimation of the natural eigen directions of the medium when the range of offset angles does not exceed 35*. The proposed method is validated with synthetic RVSP data for two models with different densities of vertical fractures. Results show good accuracy in the estimation of the angle of the fractures for the whole range of offsets. The study also extends to show the dependence on the frequency and on the offset.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1999

Author dc:creator

• Sierra T., Jesús V. (Jésus Vicente), 1965-

Advisor dc:contributor.advisor

• M. Nafi Toksöz.

• Earth, Atmospheric, and Planetary Sciences

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/58164

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/58164