Methods and apparatus utilizing a derivative of a fluorescene signal for measuring the characteristics of a multiphase fluid flow in a hydrocarbon well
US6075611A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 1998 |
| Grant date | Jun 13, 2000 |
| Priority date | — |
| Expiry date | May 7, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/64
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Single point optical probes for measuring three-phase characteristics of fluid flow in a hydrocarbon well and methods of processing signals generated by the probe are disclosed. A single fiber optic probe is coupled to a light source and apparatus for detecting reflectance and fluorescence. Light is delivered to the tip of the probe where it exits the probe and illuminates the liquid ambient the probe tip or is internally reflected in the probe when gas is located at the probe tip. If the fluid at the probe tip is oil, the light exits the probe, illuminates the oil, and causes the oil to fluoresce. According to one signal processing method of the invention, the reflectance signal is binarized at a threshold to provide a gas/liquid quasi-binary signal which changes over time. A time fraction of the signal values is used to calculate the gas holdup. According to other signal processing methods of the invention, the fluorescence indication signal is processed by taking its derivative (and if desired a second derivative) to determine the "corners" of the fluorescence signal over time. The derivative signal exhibits a positive and a negative peak which are separated by time. The time be…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.