# US 9,752,426 B2 · Well ranging apparatus, systems, and methods

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- Number: US 9,752,426 B2
- Document ID: US9752426B2
- Status: Granted
- Kind: B2
- Application number: 14/769,476
- Filed: 2015-08-04
- Published: 2016-09-22
- Granted: 2017-09-05
- Earliest claimed: 2014-08-11
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Hsu-Hsiang Wu
- Web page: https://patentgrep.com/patent/US9752426B2

## CPC

- E21B 47/0228: using electromagnetic energy or detectors therefor
- E21B 7/04: Directional drilling
- E21B 33/14: for cementing casings into boreholes
- E21B 47/024: of devices in the borehole (determining slope or direction of the borehole E21B47/022)
- E21B 47/12: Means 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 3/26: operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30)
- G01V 20/00: Geomodelling in general
- G06F 17/11: for solving equations {, e.g. nonlinear equations, general mathematical optimization problems (optimization specially adapted for a specific administrative, business or logistic context G06Q10/04)}
- E21B 43/2406: {Steam assisted gravity drainage [SAGD]}
- E21B 47/13: by electromagnetic energy, e.g. radio frequency
- E21B 47/18: through the well fluid {, e.g. mud pressure pulse telemetry}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Disclosed embodiments include well ranging apparatus, systems, and methods which operate to receive normal components of electromagnetic field strength azimuthal measurements within a first well at different tool azimuth angles in the first well. Further activities include determining an approximate range from the sensors to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission, using the normal components of the electromagnetic field strength azimuthal measurements. In some embodiments, the approximate range can be determined without introducing sensor azimuthal separation into range calculations. Additional apparatus, systems, and methods are disclosed.

## Claims

### Claim 1

An apparatus, comprising:
a down hole tool housing attached to at least two sensors rotatable in an azimuthal plane, each of the sensors to measure an electromagnetic field strength component comprising at least a normal component; and
a range determination module to,
receive a normal component as a first set of field strength components from each of the sensors provided by the sensors when the sensors are located at a first azimuthal location;
receive a normal component as a second set of field strength components from each of the sensors provided by the sensors when the sensors are located at a second azimuthal location different from the first azimuthal location;
determine a gradient component based on the normal components received from the first and second azimuthal locations; and
determine an approximate range based on the normal components and the gradient component from the sensors disposed in one well, to another well, via direct transmission or backscatter transmission of an electromagnetic field from the other well.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the two sensors are rotatable by at least 30 degrees, or at least 45 degrees, or at least 90 degrees in the azimuthal plane.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the two sensors comprise at least one of magnetometers or coil antennas.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the range determination module is attached to the down hole tool housing.

### Claim 5

A system, comprising:
a current source to couple current to one of a target well or a drilling well; and
an apparatus comprising a range determination module that utilizes at least two pair of sensors to,
at a first azimuthal location, receive a normal component of an electromagnetic field strength measurement of the current as a first set of field strength components and, at a second azimuthal location, receive a normal component of an electromagnetic field strength measurement of the current as a second set of electromagnetic field strength components;
determine a gradient component based on the normal components received from the first and second azimuthal locations; and
determine an approximate range based on the normal components and the gradient component from the sensors disposed in the drilling well, to the target well, via direct transmission from the target well, or via backscatter transmission from the target well.

### Claim 6 (depends on 5)

The system of claim 5, wherein the apparatus comprises an insert, and wherein at least one of the at least two pairs of sensors are attached to the insert.

### Claim 7 (depends on 5)

The system of claim 5, wherein the apparatus comprises a logging tool housing, and wherein one of the at least two pairs of sensors comprises two sensors oriented approximately 180 degrees away from each other on each side of the logging tool housing.

### Claim 8 (depends on 5)

The system of claim 5, wherein the at least two pairs of sensors comprises two pairs of gradient sensors.

### Claim 9

A method, comprising:
receiving normal components of electromagnetic field strength measurements within a first well as a first set of field strength components from at least one rotatable sensor provided by the sensor when the sensor is located at a first azimuthal location within the first well;
receiving the normal components of the electromagnetic field strength measurements as a second set of field strength components from the sensor provided by the sensor when the sensor has been rotated to be located at a second azimuthal location within the first well, wherein the first and second azimuthal locations are at approximately a same longitudinal location;
determining a gradient component based on the normal components received at the first and second azimuthal locations; and
determining an approximate range, based on the normal components and the gradient component, from the sensor disposed within the first well, to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission.

### Claim 10

A method comprising:
receiving normal components of electromagnetic field strength measurements within a first well as a first set of field strength components from at least one rotatable sensor provided by the sensor when the sensor is located at a first azimuthal location within the first well;
receiving the normal components of the electromagnetic field strength measurements as a second set of field strength components from the sensor provided by the sensor when the sensor has been rotated to be located at a second azimuthal location within the first well, wherein the first and second azimuthal locations are at approximately a same longitudinal location; and
determining an approximate range, R, from the sensor disposed within the first well, to a second well that serves as a source of an electromagnetic field, via direct transmission or backscatter transmission, wherein the at least one rotatable sensor comprises two pairs of sensors Pair1 and Pair2, and wherein the approximate range, R, is calculated using the formula:
1
(
Δ
⁢
⁢
H
2
⁢
Δ
⁢
⁢
S
H
)
Pair
⁢
⁢
1
2
+
(
Δ
⁢
⁢
H
2
⁢
Δ
⁢
⁢
S
H
)
Pair
⁢
⁢
2
2
=
1
4
⁢
⁢
cos
2
⁢
θ
R
2
+
4
⁢
sin
2
⁢
θ
R
2
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
=
R
2
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
wherein H is one of the normal components of the electromagnetic field strength measurements, ΔH is a difference between the first and second set of field strength components, ΔS is a separation between one of the sensors and a tool center, R is the approximate range, and θ is a ranging angle.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
electrically coupling a current source to the second well to enable the direct transmission of the electromagnetic field from the second well.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
launching an electromagnetic wave from the first well to enable the backscatter transmission of the electromagnetic field from the second well.

### Claim 13 (depends on 1)

The apparatus of claim 1, wherein the approximate range, R, is calculated by determining a ranging angle θ, using the formula:
H
Δ
⁢
⁢
H
/
2
⁢
Δ
⁢
⁢
S
=
-
R
2
+
Δ
⁢
⁢
S
2
2
⁢
⁢
R
⁢
⁢
cos
⁢
⁢
θ
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
,
where H is one of the normal components of the electromagnetic field strength measurements, ΔH is a difference between the first and second set of field strength components, and ΔS is a separation between one of the two sensors and a center of a ranging tool on which the sensors are located.

### Claim 14

A system, comprising:
a current source to couple current to one of a target well or a drilling well; and
an apparatus comprising a range determination module to receive a normal component of an electromagnetic field strength measurement of the current as a first set of field strength components and a second set of electromagnetic field strength components from at least two pairs of sensors Pair1 and Pair2 within the drilling well, and to determine an approximate range, R, from the sensors disposed in the drilling well, to the target well, via direct transmission from the target well, or via backscatter transmission from the target well, wherein R is calculated using the formula:
1
(
Δ
⁢
⁢
H
2
⁢
Δ
⁢
⁢
S
H
)
Pair
⁢
⁢
1
2
+
(
Δ
⁢
⁢
H
2
⁢
Δ
⁢
⁢
S
H
)
Pair
⁢
⁢
2
2
=
1
4
⁢
⁢
cos
2
⁢
θ
R
2
+
4
⁢
sin
2
⁢
θ
R
2
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
=
R
2
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
wherein H is one of the normal components of the electromagnetic field strength measurements, ΔH is a difference between the first and second set of field strength components, ΔS is a separation between one of the sensors and a tool center, R is the approximate range, and θ is a ranging angle.

### Claim 15 (depends on 9)

The method of claim 9, wherein the approximate range, R, is calculated by determining a ranging angle θ, using the formula:
H
Δ
⁢
⁢
H
/
2
⁢
Δ
⁢
⁢
S
=
-
R
2
+
Δ
⁢
⁢
S
2
2
⁢
⁢
R
⁢
⁢
cos
⁢
⁢
θ
⁢
(
1
+
(
Δ
⁢
⁢
S
R
)
2
)
,
where H is one of the normal components of the electromagnetic field strength measurements, ΔH is a difference between the first and second set of field strength components, and ΔS is a separation between the sensor and a center of a ranging tool on which the sensor is located.