The Estimation of the Cylindrical Wave Reflection Coefficient.
Abstract
In the acoustic well logging problem an acoustic source and an array of receivers are placed in a borehole for the purpose of resolving the acoustic properties of the surrounding formation. In the existing approach to this problem, a received array is placed at a large offset from the source and energy refracted by the formation is analyzed. Here, a short-offset array is used to analyze energy reflected by the formation. The formation is modeled as cylindrically stratified and the concepts and properties of the monochromatic cylindrical wave and the cylindrical wave reflection coefficient are developed. The reflection coefficient as a function of frequency, but at a single axial wavenumber, is estimated from the reflected component of the total field on the axis of the borehole. A rapid method for generating arrays of synthetic acoustic logging data is developed and the data is used to test and evaluate the iterative Maximum Likelihood (ML) dereverberation scheme. The reflection coefficient estimates are found to be accurate within the passband of the source pulse except at those frequencies which excite modes. The estimation performance is sensitive to the array design and to the signal-to-noise ratio.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1982
- Accession Number
- ADA119420
Entities
People
- Andrew Loris Kurkjian
Organizations
- Massachusetts Institute of Technology