Measurement of formation characteristics using acoustic borehole tool having sources of different frequencies
US5521882A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1994 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | Aug 31, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0422
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus and methods for determining an indication of a nonlinear property of a formation traversed by a borehole are provided. An acoustic tool is used in a borehole to generate first and second signals of different frequencies. As a result of nonlinearities in the formation, the mixing of the first and second signals results in a third signal having a frequency equal to the difference of the frequencies of the first and second signals. The amplitude of the third signal is measured by a detector, and the indication of nonlinearity of the formation is determined according to a relationship which relates the measured amplitude at the measured frequency to the amplitudes of the first and second signals, the frequency of measurement, the velocity of the measured wave, the distance of the receiver from the source, and a function of the nonlinear and linear parameters of the formation. The indication of nonlinearity may then be utilized to give an indication of the relative consolidation of the formation surrounding the borehole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.