Method and apparatus for acoustic logging of fluid density and wet cement plugs in boreholes
US6050141A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1998 |
| Grant date | Apr 18, 2000 |
| Priority date | — |
| Expiry date | Aug 28, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/02818
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of determining the acoustic impedance of a fluid in a borehole, by gating a reflected acoustic signal into a plurality of time slots, and comparing received energies of the signal for the time slots to obtain a value indicative of the acoustic impedance of the fluid. The value may be normalized to yield the acoustic impedance of the fluid using the acoustic impedance of, e.g., water as a calibration point. The comparison is performed by comparing a ratio of an integration of a first ring down time slot and a second ring down time slot, to an integration of an internal reflection time slot. The acoustic pulse may be generated using a transducer immersed in an intermediate fluid contained within a chamber defined in part by a plate in contact with the borehole fluid and having a thickness such that a mechanical resonance frequency of the plate in a thickness mode is substantially equal to a resonance frequency of the transducer. The sonic velocity of the fluid is also measured and, when combined with the acoustic impedance, is used to determine the fluid density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.