US 12,241,365 B2
Optical cable, optical cable monitoring system, and well monitoring method
Kinzo Kishida, Kobe (JP); Ahmad Riza Ghazali, Kajang (MY); and Mohamad Faizal bin Abd Rahim, Kajang (MY)
Assigned to PETROLIAM NASIONAL BERHAD (PETRONAS), Kuala Lumpur (MY)
Appl. No. 17/635,600
Filed by PETROLIAM NASIONAL BERHAD (PETRONAS), Kuala Lumpur (MY)
PCT Filed Aug. 14, 2020, PCT No. PCT/MY2020/050069
§ 371(c)(1), (2) Date Feb. 15, 2022,
PCT Pub. No. WO2021/034184, PCT Pub. Date Feb. 25, 2021.
Claims priority of application No. MYPI 2019004724 (MY), filed on Aug. 16, 2019.
Prior Publication US 2022/0364460 A1, Nov. 17, 2022
Int. Cl. G01B 11/16 (2006.01); E21B 47/117 (2012.01)
CPC E21B 47/117 (2020.05) [G01B 11/16 (2013.01)] 5 Claims
OG exemplary drawing
 
1. An optical cable comprising:
an optical fiber;
a strand including a plurality of cables provided in a radial direction of the optical fiber, the plurality of cables being twisted so as to surround an outer circumference of the optical fiber and arranged in an annular shape;
a second strand including a plurality of cables provided in the radial direction of the optical fiber, the plurality of cables being twisted so as to surround an outer circumference of the strand and arranged in an annular shape, the plurality of cables having a larger outer diameter than the cables of the strand;
a physical quantity measurement optical fiber provided so as to replace one of the cables of the second strand and configured to measure temperature, strain, or pressure which is a physical quantity of a measurement target;
a third strand including a plurality of cables provided in the radial direction of the optical fiber, the plurality of cables being twisted so as to surround an outer circumference of the second strand and arranged in an annular shape, the plurality of cables having a larger outer diameter than the cables of the second strand; and
hydrocarbon absorbing resin configured to absorb hydrocarbon and filling gaps between the optical fiber, the strand, the second strand, and the third strand,
wherein frequency shift in signals from the physical quantity measurement optical fiber, influenced by the physical quantities including temperature, strain, or pressure, is used to correct signals from the optical fiber, so that frequency shift in the corrected signals is influenced only by expansion of the hydrocarbon absorbing resin caused by the absorbed hydrocarbon.