Pressure tuned infrared light emitting diode for downhole spectroscopy

Abstract

Fluid is sampled from a subterranean formation with a downhole tool from inside a wellbore intersecting the formation. The fluid is analyzed by a spectrometer inside the downhole tool. A light source in the spectrometer is pressure tuned to compensate for a change in wavelength of the output light due to a temperature change in the wellbore, and overlap with a compound of interest or analyte absorption band. The light source is in a fluid filled chamber, and a piezoelectric stack is in a cylinder that has an open end connected to the chamber. The fluid and the light source are selectively pressurized by expanding the piezoelectric stack at frequencies ranging up to at least around 1000 hertz. When pressurized, the output light wavelength is shifted to a range that coincides with a spectral response of a particular compound or compounds. The piezoelectric stack expands in response to electricity.

Dependencies are inferred from the claim text.