Method and apparatus for a derivative spectrometer
AssigneeBaker Hughes Incorporated
InventorsRocco DiFoggio, Arnold Walkow, Paul Bergren
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Abstract
The invention comprises a method of adapting derivative spectrometry for use in a downhole environment and addresses problems that are inherent in this environment. Such problems include, but are not limited to, elevated temperatures and scattering from particles residing within dirty fluid samples. The invention improves the resolution by measuring the first derivative of the spectrum. The derivative spectrometer of this invention operates by vibrating a linear variable interference filter back and forth along the plane of the filter or by oscillating a circular variable filter about some angle.
Claims25
A downhole spectrometer comprising:
- a sonde containing a spectrometer for traversing a bore hole, the spectrometer comprising:
- a collimated light source for illuminating a sample;
- a sample chamber for containing the sample;
- a variable filter having a an average wavelength centered about an absorption peak of the sample, to encounter light from the sample;
- a vibrating actuator attached to the variable filter for moving the variable filter;
- and
- a photodetector array for sensing light passing through the variable fitter.
A method for downhole spectrometetry comprising:
- traversing a borehole with a sonde containing a spectrometer;
- containing a sample in a sample chamber;
- illuminating the sample with a collimated light source;
- passing light from the sample through a variable filter;
- moving the variable filter;
- and
- sensing light passing through the variable filter with a photodetector.
Dependencies are inferred from the claim text.