US 12,092,779 B2
Simultaneous distributed acoustic sensing with multiple gauge lengths
Kwang Il Suh, Houston, TX (US); Neha Sahdev, Tomball, TX (US); and Ira Bush, Los Angeles, CA (US)
Assigned to HALLIBURTON ENERGY SERVICES, INC., Houston, TX (US)
Filed by HALLIBURTON ENERGY SERVICES, INC., Houston, TX (US)
Filed on Jan. 31, 2022, as Appl. No. 17/589,138.
Prior Publication US 2023/0243989 A1, Aug. 3, 2023
Int. Cl. G01V 1/22 (2006.01); E21B 47/008 (2012.01); E21B 47/113 (2012.01); E21B 47/117 (2012.01); E21B 47/135 (2012.01); E21B 49/00 (2006.01); G01D 5/353 (2006.01)
CPC G01V 1/226 (2013.01) [E21B 47/008 (2020.05); E21B 47/114 (2020.05); E21B 47/117 (2020.05); E21B 47/135 (2020.05); E21B 49/00 (2013.01); G01D 5/35325 (2013.01); G01D 5/35329 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A distributed acoustic sensing system, comprising:
a first interferometer having a first gauge length, a first arm, and a second arm, wherein the first arm of the first interferometer has a first path length, the second arm of the first interferometer has a second path length, and a path length difference corresponds to a difference between the first path length and the second path length of the first interferometer;
a second interferometer having a second gauge length, wherein the second gauge length is different from the first gauge length;
a pulse generator that transmits optical pulses at a fixed rate with varying pulse widths to adjust a spatial resolution of the distributed acoustic sensing system;
a coupler, communicatively coupled to the pulse generator, that:
directs the optical pulses transmitted at the fixed rate with the varying pulse widths down an optical fiber, and
directs backscattered light associated with the optical pulses transmitted at the fixed rate with the varying pulse widths from the optical fiber;
a splitter, communicatively coupled to the coupler, the first interferometer, and the second interferometer, wherein:
the path length difference of the first interferometer is changed to further adjust the spatial resolution of the distributed acoustic sensing system, and
the splitter splits the backscattered light into a first portion for the first interferometer and a second portion for the second interferometer;
a first photodetector assembly to detect a first interferometric signal from the first interferometer responsive to the first portion of backscattered light;
a second photodetector assembly to detect a second interferometric signal from the second interferometer responsive to the second portion of backscattered light; and
an information handling system, coupled to the first and the second photodetector assemblies, to receive and process the first and the second interferometric signals for at least two different sensing applications adapted for the first and the second gauge lengths, respectively, wherein the processing of the first and the second interferometric signals for the at least two different sensing applications is based on the optical pulses being transmitted at the fixed rate with the varying pulse widths.