Optical spectrometer and downhole spectrometry method
AssigneeSchlumberger Technology Corporation
InventorsKentaro Indo, Kai Hsu, Julian Pop
Life of this patent
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Abstract
An optical spectrometer includes a near black body light source, a reference detector in a first optical path and a single measurement detector in a second optical path. A sample cell including a fluid flow line may be positioned in the second optical path upstream of the measurement detector. Optical energy may be emitted at a plurality of filament temperatures and first and second sets of optical intensities measured at the reference and measurement detectors. The first and second sets of optical intensities may be processed to compute a substantially continuous transmittance spectrum of a fluid sample in the fluid flow line by inverting the acquired optical intensity measurements.
Claims4
A method for obtaining a substantially continuous transmittance spectrum of a fluid sample, the method comprising:
- (a) receiving the fluid sample at an optical spectrometer;
- (b) emitting near black body optical energy at a plurality of filament temperatures by incrementing an applied electrical current or electrical voltage through a predetermined range of values, the optical energy passing through a beam splitter into first and second optical paths, the second optical path passing through the fluid sample;
- (c) measuring a first set of optical intensities at a reference detector in the first path, the optical intensities in the first set corresponding to the plurality of filament temperatures;
- (d) measuring a second set of optical intensities at a single measurement detector in the second optical path, the optical intensities in the second set corresponding to the plurality of filament temperatures, and wherein no filter is disposed between the beam splitter and the single measurement detector;
- and
- (e) processing the optical intensities measured in (c) and (d) to compute the substantially continuous transmittance spectrum of the fluid sample;
- wherein computing the transmittance spectrum comprises solving the integral equation:
- In=∫hn(λ)·S(λ)dλ
- wherein I represents optical density, h represents radiant spectrum, λ represents wavelength, S represents transmittance spectrum, and n represents an integer.
Dependencies are inferred from the claim text.