Determining dew precipitation and onset pressure in oilfield retrograde condensate
US7002142B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 2002 |
| Grant date | Feb 21, 2006 |
| Priority date | — |
| Expiry date | Jun 12, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N33/2823
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus detects dew precipitation and determines dew precipitation onset pressure in a sample of formation fluid located downhole in an oilfield reservoir. In a preferred embodiment, the method includes (a) isolating a sample of formation fluid downhole; (b) illuminating the sample downhole with fluorescence excitation light; (c) measuring at least one characteristic of fluorescence short from the sample; (d) reducing pressure on the sample; (e) repeating steps (b) to (d); (f) detecting dew precipitation when a change is detected in a parameter that is a function of the at least one characteristic of fluorescence emission; and (g) setting dew precipitation onset pressure equal to pressure on the sample when the change in the parameter is detected. The parameter preferably is a function of fluorescence intensity and fluorescence red shift, and the change is an increase in fluorescence intensity and detection of fluorescence red shift. Also, the function includes a ratio of a measured intensity at a first wavelength to a reference intensity, and the reference intensity is a function of a measured intensity at a second wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.