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AssigneeSCHLUMBERGER TECHNOLOGY CORPORATION, Incorporated in the State of Texas
InventorsOliver C. Mullins, Go Fujisawa, Chengli Dong, Andrew Kurkjian, John Nighswander, Toru Terabayashi, Satoko Yoshida, Hideki Kinjo, Henning Groenzin
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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.
A method for detecting dew precipitation in a sample of formation fluid located downhole in an oilfield reservoir, comprising:
A method for detecting dew precipitation in a sample of formation fluid located downhole in an oilfield reservoir, comprising:
A tool for detecting dew precipitation in a fluid sample located downhole in an oilfield reservoir, comprising:
A tool for detecting dew precipitation in a fluid sample located downhole in an oilfield reservoir, comprising:
Dependencies are inferred from the claim text.