USA As Represented by Secretary of the Navy

Halliburton Energy Services, Inc.

Welldynamics, B.v.

Todd, Michael D.

Leblanc, Michael

Michael D Todd

Gregg A Johnson

Neal Gregory Skinner

John R Dennis

Bryan L Althouse

Chia-Chen Chang

Michel Joseph Leblanc

Michael Leblanc

Michel Leblanc

A well pressure and temperature measurement system and method are provided. In a described embodiment, a sensor system includes multiple strain sensors attached to a structure which changes dimensionally in response to well pressure and temperature changes. The strain sensors may be fiber optic sensors. The structure may be tubular and the strain sensors may detect axial and hoop strains in the structure.

Subterranean well pressure and temperature measurement

A new optical sensing device containing fiber Bragg gratings, a scanning bandpass filter, an interferometer and multiple photodetectors is disclosed. The present invention also describes a new system and method for fibre Bragg grating (FBG) sensor interrogation and multiplexing. The new system combines a scanning Fabry-Perot (SFP) bandpass filter used to wavelength-multiplex multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fibre interferometer made with a 3&times;3 coupler to detect strain-induced wavelength shifts. A passive technique for interferometer drift compensation using non-sensing FBGs is included in the system. A complete prototype system interrogates four gratings in a single fiber at a Nyquist sampling rate up to 10 kHz, with a noise floor measured near 4 n&egr; Hz above 0.1 Hz. The inclusion of the interferometer drift compensation technique is shown to make quasi-static measurements feasible.

Optical sensing device containing fiber Bragg gratings

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Alexandria, VA, United States of America

Michael D Todd