The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 1997
Filed:
May. 31, 1996
Xiaoming Tang, Sugar Land, TX (US);
Western Atlas International, Inc., Houston, TX (US);
Abstract
A method for detecting alteration of earth formations penetrated by a wellbore. The method includes determining a first arrival velocity of dipole acoustic energy propagated through the earth formations. A first frequency dependent velocity of the dipole acoustic energy is then determined. A first dispersion characteristic is determined from the difference between the first arrival and frequency dependent velocities. The method includes determining a frequency dependent velocity and a first arrival velocity for synthesized waveforms for an unaltered formation. The synthesis uses the first arrival velocity of the dipole acoustic energy as a shear velocity. A second dispersion characteristic, related to a difference between the frequency dependent velocity and the first arrival velocity of the synthesized waveforms is determined. The alteration is detected by finding a difference between the first dispersion characteristic and the second dispersion characteristic. In a preferred embodiment, the frequency dependent velocity includes a peak energy velocity determined by waveform matching the receiver signals.