US 2020/0049853 A1 · Differential Attenuation Compensation For Distributed Temperature Sensing Systems

Abstract

An interrogation system includes lasers and an optical filtering device. The lasers include a primary set of lasers coupled to a primary multiplexer for generating primary light signals and a secondary set of lasers coupled to a secondary multiplexer for generating secondary light signals. The primary set of lasers may generate light signals having a first set of overlapping wavelengths and the secondary set of lasers may generate light signals having a second set of overlapping wavelengths. The optical filtering device may route the primary light signal and the secondary light signal to an optical fiber sensing cable positioned in a wellbore and receive reflection signals corresponding to the primary light signal and the secondary light signal. The reflection signals corresponding to the secondary light signal may have a first wavelength range that matches a second wavelength range of the primary light signals.

Claims20

Dependent claims

An interrogation system, comprising:

a plurality of lasers including a primary set of lasers coupled to a primary multiplexer for generating primary light signals that have a first set of overlapping wavelengths and a secondary set of lasers coupled to a secondary multiplexer for generating secondary light signals that have a second set of overlapping wavelengths;
and
an optical filtering device communicatively couplable to the plurality of lasers to route the primary light signals to an optical fiber sensing cable positioned in a wellbore and route the secondary light signals to the optical fiber sensing cable separate from the primary light signals, the optical filtering device including a common port couplable to the optical fiber sensing cable to receive reflection signals corresponding to the primary light signals and reflection signals corresponding to the secondary light signals, wherein the reflection signals corresponding to the secondary light signals have a wavelength range that matches the wavelength range of the primary light signals.

A distributed temperature sensing system, comprising:

an optical fiber sensing cable extending downhole in a wellbore, the optical fiber sensing cable including an optical fiber cable having one or more sensors for sensing temperature in a section of the wellbore;
one or more optical switches positioned in an optical path between two or more light sources and the optical fiber sensing cable to route a primary light signal to the optical fiber sensing cable and the secondary light signal to the optical fiber sensing cable separate from the primary light signal, the primary light signal corresponding to a first multiplexed signal having a first wavelength range and the secondary light signal corresponding to a second multiplexed signal having a second wavelength range, wherein the optical fiber sensing cable is positioned at an end of the optical path to receive the secondary light signal from the one or more optical switches and route a reflection signal corresponding to a reflection of the secondary light signal toward the one or more optical switches, the reflection signal having a wavelength range that matches the first wavelength range.

Dependencies are inferred from the claim text.

Differential Attenuation Compensation For Distributed Temperature Sensing Systems

Life of this patent

Differential Attenuation Compensation For Distributed Temperature Sensing Systems

Life of this patent

Abstract

Claims20