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1. GB2542924 - Optical fiber distributed sensors with improved dynamic range

Office United Kingdom
Application Number 201614740
Application Date 14.01.2015
Publication Number 2542924
Publication Date 05.04.2017
Publication Kind A
IPC
E21B 47/12
EFIXED CONSTRUCTIONS
21EARTH OR ROCK DRILLING; MINING
BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
47Survey of boreholes or wells
12Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
G01V 8/14
GPHYSICS
01MEASURING; TESTING
VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
8Prospecting or detecting by optical means
10Detecting, e.g. by using light barriers
12using one transmitter and one receiver
14using reflectors
G01V 8/16
GPHYSICS
01MEASURING; TESTING
VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
8Prospecting or detecting by optical means
10Detecting, e.g. by using light barriers
12using one transmitter and one receiver
16using optical fibres
CPC
E21B 47/135
E21B 47/14
EFIXED CONSTRUCTIONS
21EARTH DRILLING; MINING
BEARTH DRILLING, e.g. DEEP DRILLING
47Survey of boreholes or wells
12Means for transmitting measuring-signals ; or control signals; from the well to the surface ; or from the surface to the well; , e.g. for logging while drilling
14using acoustic waves
G01V 1/226
GPHYSICS
01MEASURING; TESTING
VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS
1Seismology; Seismic or acoustic prospecting or detecting
22Transmitting seismic signals to recording or processing apparatus
226Optoseismic systems
G01V 1/40
GPHYSICS
01MEASURING; TESTING
VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS
1Seismology; Seismic or acoustic prospecting or detecting
40specially adapted for well-logging
G02B 6/022
GPHYSICS
02OPTICS
BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
6Light guides
02Optical fibre with cladding ; with or without a coating
02057comprising gratings
02076Refractive index modulation gratings, e.g. Bragg gratings
02195characterised by means for tuning the grating
022using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper
G01V 8/14
GPHYSICS
01MEASURING; TESTING
VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS
8Prospecting or detecting by optical means
10Detecting, e.g. by using light barriers
12using one transmitter and one receiver
14using reflectors
Applicants BAKER HUGHES INC
Inventors WILLIAM JOHNSTON
Priority Data 201461940138 14.02.2014 US
2015011321 14.01.2015 US
Title
(EN) Optical fiber distributed sensors with improved dynamic range
Abstract
(EN)
An apparatus for sensing acoustic waves below a surface of the earth includes an optical fiber disposed below the surface of the earth and having a series of sensing units along the optical fiber with each sensing unit having three or more reflectors and an optical interrogator in optical communication with the optical fiber. The reflectors in each sensing unit are positioned to provide a linearized response that approximates a sawtooth wave better than a sinusoidal wave to sense the acoustic waves in a desired dynamic range. The optical interrogator is configured to transmit an input light signal into the optical fiber and receive a reflected light signal from the optical fiber due to the input light signal in order to measure a strain on each sensing unit due to interaction with the acoustic waves and to determine a location of the sensing unit corresponding to the sensed strain.