Downhole Sensing Systems and Methods Employing Spectral Analysis of Time-Division Multiplexed Pulse Sequences

摘要

An illustrative downhole sensing system and method employs an array of downhole sensors such as extrinsic Fabry-Perot interferometers, each of which provides a sequence of light pulses having spectra indicative of a measurand for that downhole sensor. An optical fiber conveys the sequences in a time-multiplexed fashion to a receiver having at least one gating element that passes only a selected one of the sequences and at least one spectrometer that receives the selected one of said sequences and responsively measures a light spectrum. Notably, the integration interval for the spectrometer measurement is substantially greater than the pulse period of each sequence, including multiple pulses within the measurement by the spectrometer.

主权项

1. A downhole sensing system that comprises:
an array of downhole sensors, each of which provides a sequence of light pulses having spectra indicative of a measurand for that downhole sensor, each of said sequences further having a pulse period; an optical fiber that conveys said sequences in a time-multiplexed fashion; a receiver coupled to the optical fiber to receive said sequences, wherein the receiver includes:
at least one gating element that passes only a selected one of said sequences; andat least one spectrometer that receives the selected one of said sequences and responsively measures a light spectrum no more than once per integration interval, wherein the integration interval is no less than twice the pulse period.