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US 10,309,830 B2Granted
Methods to correct spectrum distortion of FFPI sensors induced by dynamic wavelength dependent attenuation
AssigneeHalliburton Energy Services, Inc.
InventorsMikko Jaaskelainen, Yunmiao Wang
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Abstract
Methods are proposed for compensation of distortion in fiber Fabry-Perot interferometric (FFPI) sensors induced by dynamic wavelength dependent attenuation in subsurface wells. The methods involve measurement techniques that correct the reflective spectrum from one or more FFPI sensors utilizing a background low frequency spectrum for normalization.
Claims9
A method for compensation of distortion in fiber Fabry-Perot interferometric (FFPI) sensors induced by dynamic wavelength dependent attenuation in subsurface wells, said method comprising:
- a. installing one or more FFPI sensors into a region of interest in a subsurface well;
- b. feeding a light source through a fiber optic cable into the one or more FFPI sensors;
- c. returning an original reflective spectrum from the one or more FFPI sensors to a spectrometer for analysis;
- d. filtering the original reflective spectrum from the one or more FFPI sensors through a low-pass filter to generate an original filtered reflective spectrum;
- e. dividing the original filtered reflective spectrum by a filtered reflected spectrum obtained from the one or more FFPI sensors before installation into the region of interest in the subsurface well to obtain a normalized spectrum;
- and
- f. using the normalized spectrum to calculate changes in cavity length.
4 more elements
Dependencies are inferred from the claim text.