Accession Number : ADA119420

Title :   The Estimation of the Cylindrical Wave Reflection Coefficient.

Descriptive Note : Technical rept.,


Personal Author(s) : Kurkjian,Andrew Loris

PDF Url : ADA119420

Report Date : Jul 1982

Pagination or Media Count : 193

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.

Descriptors :   *Acoustics, *Well logging, *Linear arrays, Sound generators, Receivers, Performance(Engineering), Acoustic properties, Signal to noise ratio, Frequency, Estimates, Coefficients, Sources, Functions, Waves, Estimates, Arrays, Reflection, Pulses

Subject Categories : Recording and Playback Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE