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1. (WO2017151133) CASING THICKNESS ESTIMATION BY FREQUENCY CORRELATION

Pub. No.:    WO/2017/151133    International Application No.:    PCT/US2016/020632
Publication Date: Sat Sep 09 01:59:59 CEST 2017 International Filing Date: Fri Mar 04 00:59:59 CET 2016
IPC: E21B 47/00
G01V 1/40
G01V 1/50
Applicants: HALLIBURTON ENERGY SERVICES, INC.
Inventors: ZHANG, Zhijuan
BEDROSSIAN, Nazareth
Title: CASING THICKNESS ESTIMATION BY FREQUENCY CORRELATION
Abstract:
The thickness of borehole casing can be determined by ultrasound logging in conjunction with simulations of ultrasonic plane-wave echo waveforms across a range of frequencies for a plurality of casing thicknesses and correlation of synthetic frequency spectra derived from the simulated plane-wave echo waveforms for the various casing thicknesses against the frequency spectrum of a measured pulse-echo waveform. In accordance with various embodiments, a portion of the measured pulse-echo waveform that corresponds to the first reflection off the interface between the borehole casing and the borehole fluid is used as a driving pulse to weight the simulated plane-wave echo waveforms in the synthetic frequency spectrum.