Method for detecting cement voids or borehole washouts
US4092536A · kind A · utility
26Cited by
2References
5Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 27, 1976 |
| Grant date | May 30, 1978 |
| Priority date | — |
| Expiry date | May 27, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/107
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A fast neutron source is used to irradiate earth formations in the vicinity of a well borehole. Dual spaced epithermal neutron detectors are used to sample the epithermal neutron population at two different spaced distances from the source. A compensated formation porosity is obtained from the ratio of counting rates at the dual spaced detectors. An uncompensated porosity value is obtained from the count rate at the short spaced detector. Borehole washout or cement void regions are located by comparing the compensated and uncompensated values of formation porosity obtained in this manner.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.