# US 11,906,394 B2 · System and method for locating an area of interest in a conduit

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,906,394 B2
- Document ID: US11906394B2
- Status: Granted
- Kind: B2
- Application number: 17/046,539
- Filed: 2019-04-04
- Published: 2021-02-04
- Granted: 2024-02-20
- Earliest claimed: 2018-04-12
- Assignees: Hifi Engineering Inc.
- Applicants: Hifi Engineering Inc.
- Inventors: Arne Dankers; Seyed Ehsan Jalilian
- Web page: https://patentgrep.com/patent/US11906394B2

## CPC

- G01M 3/243: {for pipes}
- G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32)
- E21B 47/107: using acoustic means
- E21B 47/117: Detecting leaks, e.g. from tubing, by pressure testing
- E21B 47/135: using light waves, e.g. infrared or ultraviolet waves
- G01D 5/353: influencing the transmission properties of an optical fibre
- G01M 3/38: by using light (G01M3/02 takes precedence)
- G01S 7/4802: {using analysis of echo signal for target characterisation; Target signature; Target cross-section}
- G01S 7/4818: {using optical fibres}
- G01S 17/88: Lidar systems specially adapted for specific applications
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

There is described a method of locating an area of interest in a conduit, comprising: measuring multiple acoustic signals at multiple locations along the conduit; for each acoustic signal, determining its autocorrelation; and applying a relationship to the determined autocorrelations to estimate a location of the area of interest, wherein the relationship is between autocorrelations of acoustic signals measured in a modelled conduit and modelled areas of interest in the modelled conduit, wherein it is assumed that acoustic signals propagating along the modelled conduit reflect from at least one point in the modelled conduit.

## Claims

### Claim 1

A system for locating an area of interest in a conduit, the system comprising:
a conduit;
one or more optical fiber sensors positioned alongside the conduit;
an optical interrogator configured to:
transmit one or more light pulses along the one or more optical fiber sensors;
receive reflections of the one or more light pulses; and
determine from the reflections one or more interference signals; and
one or more processors communicative with the optical interrogator and with a computer- readable medium having stored thereon computer program code configured when executed by one or more processors to cause the one or more processors to perform a method comprising:
processing the one or more interference signals to obtain multiple acoustic recordings as a function of position along the conduit;
for each acoustic recording, determining its autocorrelation; and
applying a relationship to the determined autocorrelations to estimate a location of the area of interest, wherein the relationship is between autocorrelations of acoustic signals measured in a modelled conduit and modelled areas of interest in the modelled conduit, wherein it is assumed that acoustic signals propagating along the modelled conduit reflect from at least one point in the modelled conduit,
wherein determining the autocorrelations comprises determining Rw(τ, dr)=E [wm(t, dr)wm(t−τ, dr)], wherein R is the autocorrelation of the acoustic recording, τ is a time lag of the autocorrelation, dr is a position along the conduit at which the acoustic recording is obtained, E is an expected value operator, t is time, and w is the acoustic recording.

### Claim 2 (depends on 1)

The system of claim 1, wherein the method further comprises determining the relationship.

### Claim 3 (depends on 2)

The system of claim 2, wherein determining the relationship comprises modelling propagations and reflections of acoustic signals along the modelled conduit.

### Claim 4 (depends on 1)

The system of claim 1, wherein the area of interest comprises an acoustic source.

### Claim 5 (depends on 4)

The system of claim 4, wherein the acoustic source comprises a leak in the conduit.

### Claim 6 (depends on 1)

The system of claim 1, wherein the area of interest comprises a reflective interface in the conduit.

### Claim 7 (depends on 6)

The system of claim 6, wherein the reflective interface comprises a change in an interior surface of the conduit or a change in a fluid in the conduit.

### Claim 8 (depends on 1)

The system of claim 1, wherein the conduit comprises a pipeline or a wellbore.

### Claim 9 (depends on 1)

The system of claim 1, wherein the modelled conduit comprises modelled acoustic channels each corresponding to a portion of the modelled conduit, each modelled acoustic channel being modelled as a filter affecting propagation of acoustic signals along the acoustic channel.

### Claim 10 (depends on 9)

The system of claim 9, wherein each filter comprises a transfer function of the form G(q)=aq−t, wherein G is the transfer function, q is a delay operator of the form q−1s(t) =s(t−1), s is a dummy variable, a is a constant indicative of attenuation along the acoustic channel, and t is a constant indicative of an amount of time taken by an acoustic signal to travel along the acoustic channel.

### Claim 11 (depends on 1)

The system of claim 1, wherein estimating the location of the area of interest comprises using the determined autocorrelations to determine a distance to the area of interest as a function of time lag of the autocorrelations.

### Claim 12 (depends on 11)

The system of claim 11, wherein estimating the location of the area of interest comprises generating a plot of the distance to the area of interest as a function of the time lag of the autocorrelations.

### Claim 13 (depends on 12)

The system of claim 12, wherein the area of interest comprises an acoustic source, and wherein estimating the location of the area of interest comprises determining
d
s
=
y
⁢
v
2
v
1
,
wherein ds is a distance to the location of the area of interest, y is a y-intercept corresponding to one or more lines of the plot, and vi and v2 are time lags corresponding to one or more lines of the plot.

### Claim 14 (depends on 12)

The system of claim 12, wherein the area of interest comprises an acoustic source, and wherein estimating the location of the area of interest comprises determining
d
s
=
1
2
⁢
(
d
l
-
y
)
+
d
l
2
⁢
v
2
v
1
+
v
2
,
wherein ds is a distance to the location of the area of interest, y is a y-intercept corresponding to one or more lines of the plot, v1 and v2 are time lags corresponding to one or more lines of the plot, and di is a length of the conduit.

### Claim 15 (depends on 12)

The system of claim 12, wherein the area of interest comprises a reflective interface in the conduit, and wherein estimating the location of the area of interest comprises determining a y-intercept corresponding to one or more lines of the plot.

### Claim 16 (depends on 12)

The system of claim 12, wherein the area of interest comprises a reflective interface in the conduit, and wherein estimating the location of the area of interest comprises determining
d
i
=
1
2
⁢
y
+
1
2
⁢
v
1
⁢
d
l
v
1
+
v
2
,
wherein di is a distance to the location of the area of interest, y is a y-intercept corresponding to one or more lines of the plot, v1 and v2 are time lags corresponding to one or more lines of the plot, and di is a length of the conduit.

### Claim 17 (depends on 1)

The system of claim 1, wherein the multiple acoustic recordings are obtained in respect of different periods of time.