US 12,481,081 B2
Downhole monitoring using few-mode optical fiber based distributed acoustic sensing
Frode Hveding, Dhahran (SA); Islam Ashry, Thuwal (SA); Mao Yuan, Thuwal (SA); Mohd Sharizal Bin Alias, Thuwal (SA); Boon Siew Ooi, Thuwal (SA); and Muhammad Arsalan, Dhahran (SA)
Assigned to Saudi Arabian Oil Company, Dhahran (SA); and King Abdullah University of Science and Technology, Thuwal (SA)
Filed by Saudi Arabian Oil Company, Dhahran (SA); and King Abdullah University of Science and Technology, Thuwal (SA)
Filed on May 13, 2024, as Appl. No. 18/662,537.
Application 18/662,537 is a continuation of application No. 16/299,918, filed on Mar. 12, 2019, granted, now 12,019,200.
Prior Publication US 2024/0295669 A1, Sep. 5, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G01V 1/52 (2006.01); E21B 47/00 (2012.01); G01D 5/26 (2006.01); G01V 1/50 (2006.01); G01V 8/16 (2006.01)
CPC G01V 1/52 (2013.01) [E21B 47/00 (2013.01); G01D 5/268 (2013.01); G01V 1/50 (2013.01); G01V 8/16 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A vibration sensor system comprising:
a light pulse generator configured to provide a plurality of optical pulses;
an optical fiber having a plurality of modes and a predetermined length and configured to guide the optical pulses; and
a sensor optically coupled to the optical fiber and configured to determine a location and frequency of a vibration of the optical fiber at a location along the optical fiber, based on a collection of distortion parameters that are descriptive of intermodal distortion effects of intermodal coupling within the optical fiber, wherein determining the location and frequency comprises:
receiving a plurality of distorted backscattered Rayleigh signals from the optical fiber, wherein the plurality of distorted backscattered Rayleigh signals are based on an original backscattered Rayleigh signal backscattered by a vibration of the optical fiber at a vibration frequency and a vibration amplitude at a vibration location along the optical fiber and distorted by intermodal coupling among the plurality of modes; and
transforming, by a processor, the plurality of distorted backscattered Rayleigh signals into an undistorted backscattered Rayleigh signal based on the collection of distortion parameters, wherein the undistorted backscattered Rayleigh signal is substantially a recovered version of the original backscattered Rayleigh signal.