# US 8,570,834 B2 · Method of acoustic ranging

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- Number: US 8,570,834 B2
- Document ID: US8570834B2
- Status: Granted
- Kind: B2
- Application number: 12/869,401
- Filed: 2010-08-26
- Published: 2012-03-01
- Granted: 2013-10-29
- Earliest claimed: 2010-08-26
- Assignees: Schlumberger Technology Corporation
- Applicants: Graham A. McElhinney
- Inventors: Graham A. McElhinney
- Web page: https://patentgrep.com/patent/US8570834B2

## CPC

- G01S 5/22: Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/28 takes precedence)
- E21B 47/0224: using seismic or acoustic means
- 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

## Abstract

An acoustic surveying method includes computing at least one of a distance and direction between first and second subterranean boreholes. An acoustic pulsed is transmitted into a subterranean formation from the first borehole and received at three or more spaced receivers deployed in the second borehole. A distance between the two boreholes may be determined using longitudinally spaced receivers while a toolface to target direction (angle) may be determined using circumferentially spaced receivers.

## Claims

### Claim 1

A method for surveying a subterranean borehole, the method comprising:
(a) deploying an acoustic transmitter in a first borehole;
(b) deploying first, second, and third longitudinally spaced acoustic receivers in a second borehole;
(c) firing the acoustic transmitter to launch an acoustic pulse;
(d) receiving corresponding acoustic waveforms at each of the first, second, and third acoustic receivers; and
(e) processing the acoustic waveforms received in (d) in combination with at least one longitudinal spacing between the first, second, and third acoustic receivers to compute first and second pole angles; and
(f) processing the first and second pole angles computed in (e) to further compute a distance between the first borehole and the second borehole.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the acoustic transmitter is located on a bottom hole assembly of a drill string deployed in the first borehole; and
the first, second, and third acoustic receivers are located on a wireline acoustic receiving tool deployed in the second borehole.

### Claim 3 (depends on 1)

The method of claim 1, wherein (e) further comprises:
(i) processing the acoustic waveforms received in (d) to determine a first time delay between acoustic arrivals at the first receiver and the second receiver and a second time delay between acoustic arrivals at the second receiver and the third receiver; and
(ii) processing the first time delay and the second time delay to compute the distance.

### Claim 4 (depends on 3)

The method of claim 3, wherein the first and second time delays are determined with respect to at least one of a compressional wave and a shear wave.

### Claim 5 (depends on 1)

The method of claim 1, wherein (e) further comprises:
(i) processing the acoustic waveforms received in (d) to determine a first time delay between acoustic arrivals at the first receiver and the second receiver and a second time delay between acoustic arrivals at the second receiver and the third receiver; and
(ii) processing the first time delay and the second time delay to compute the first and second pole angles.

### Claim 6 (depends on 5)

The method of claim 5, wherein the first and second pole angles are computed in (ii) according to the equations:
θ
1
=
arc
⁢
⁢
sin
⁡
(
v
⁢
⁢
Δ
⁢
⁢
t
1
d
)
θ
2
=
arc
⁢
⁢
sin
⁡
(
v
⁢
⁢
Δ
⁢
⁢
t
2
d
)
wherein θ1 and θ2 represent the first and second poles angles, θ represents an acoustic velocity of a formation, d represents the longitudinal spacing between the first and second acoustic receivers and the second and third acoustic receivers, and Δt1 and Δt2 represent the first and second time delays.

### Claim 7 (depends on 5)

The method of claim 5, wherein the distance is computed according to at least one of the following equations:
D
1
=
d
⁢
⁢
cos
⁢
⁢
θ
1
sin
⁡
(
θ
2
-
θ
1
)
D
2
=
d
⁢
⁢
cos
⁢
⁢
θ
2
sin
⁡
(
θ
2
-
θ
1
)
D
T
=
d
⁢
⁢
cos
⁢
⁢
θ
1
⁢
cos
⁢
⁢
θ
2
sin
⁡
(
θ
2
-
θ
1
)
wherein D1 represents a distance between the acoustic transmitter and the first acoustic receiver, D2 represents a distance between the acoustic transmitter and the second acoustic receiver, DT represents a transverse distance between the acoustic transmitter and the second borehole, θ1 and θ2 represent the first and second poles angles, ν represents an acoustic velocity of a formation, and d represents the longitudinal spacing between the first and second acoustic receivers and the second and third acoustic receivers.

### Claim 8 (depends on 1)

The method of claim 1, wherein the distance is a transverse distance between the acoustic transmitter and the second borehole.

### Claim 9

A method for surveying a subterranean borehole, the method comprising:
(a) deploying an acoustic transmitter in a first borehole;
(b) deploying first, second, and third circumferentially spaced acoustic receivers in a second borehole;
(c) firing the acoustic transmitter to launch an acoustic pulse;
(d) receiving corresponding acoustic waveforms at each of the first, second, and third acoustic receivers; and
(e) processing the acoustic waveforms received in (d) to determine a toolface to target angle between the first and second boreholes.

### Claim 10 (depends on 9)

The method of claim 9, wherein:
the acoustic transmitter is located on a bottom hole assembly of a drill string deployed in the first borehole; and
the first, second, and third acoustic receivers are located on a wireline acoustic receiving tool deployed in the second borehole.

### Claim 11 (depends on 9)

The method of claim 9, wherein (e) further comprises:
(i) processing the acoustic waveforms received in (d) to determine a first time delay between acoustic arrivals at the first receiver and the second receiver and a second time delay between acoustic arrivals at the first receiver and the third receiver; and
(ii) processing the first time delay and the second time delay to compute the toolface to target angle.

### Claim 12 (depends on 11)

The method of claim 11, wherein the toolface to target angle is computed using the following equation:
TFT
=
β
+
ϕ
=
arc
⁢
⁢
sin
⁡
(
Δ
⁢
⁢
t
1
-
Δ
⁢
⁢
t
2
Δ
⁢
⁢
t
MAX
)
+
ϕ
where TFT represents the toolface to target angle with respect to a reference direction, β represents the tool face to target angle with respect to the first acoustic receiver, φ represents an angular separation between the first acoustic receiver and a reference direction, Δt1 and Δt2 represent the first and second time delays, and ΔtMAX represents a maximum time delay between any two of the first, second, and third acoustic receivers.

### Claim 13 (depends on 12)

The method of claim 12, wherein ΔtMAX is determined empirically.

### Claim 14 (depends on 12)

The method of claim 12, wherein ΔtMAX is computed based upon an acoustic velocity of a formation.

### Claim 15 (depends on 12)

The method of claim 12, wherein the reference direction is a high side of the second borehole.

### Claim 16 (depends on 9)

The method of claim 9, wherein (e) further comprises:
(i) processing the acoustic waveforms received in (d) to determine a time delay between acoustic arrivals at the second receiver and the third receiver; and
(ii) processing the time delay to compute the toolface to target angle.

### Claim 17

A method for surveying a subterranean borehole, the method comprising:
(a) deploying an acoustic transmitter in a first borehole;
(b) deploying at least first and second sets of longitudinally spaced acoustic receivers in the second borehole, each of the first and second sets of acoustic receivers including corresponding first, second, and third circumferentially spaced acoustic receivers;
(c) firing the acoustic transmitter to launch an acoustic pulse;
(d) receiving corresponding acoustic waveforms at each of the first and second sets of acoustic receivers; and
(e) processing the acoustic waveforms received in (d) to determine at least first and second toolface to target angles between the first and second boreholes.

### Claim 18 (depends on 17)

The method of claim of claim 17, further comprising:
(f) processing the first and second toolface to target angles obtained in (e) to determine at least one distance between the first and second boreholes.

### Claim 19 (depends on 17)

The method of claim 17, wherein:
the acoustic transmitter is located on a bottom hole assembly of a drill string deployed in the first borehole; and
the first and second sets of acoustic receivers are located on a wireline acoustic receiving tool deployed in the second borehole.