BORING TOOL TRACKING/GUIDING SYSTEM AND METHOD WITH UNCONSTRAINED TARGET LOCATION GEOMETRY

• US 20050212519A1
• Filed: 05/24/2005
• Published: 09/29/2005
• Est. Priority Date: 11/20/2001
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Brune, Guenter W., Chau, Albert W.
• Granted Patent: US 6,975,119 B2
• Time in Patent Office: Days
• US Class Current: 324/326
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 7/04 Directional drilling
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

Tracking a boring tool is performed within an underground region using a locating signal. The boring tool is moved through the ground during a series of distance movements such that potential movement of the boring tool during any one of the distance movements is less than a maximum movement value. A current positional relationship is determined for a current one of the distance movements based on: a last-determined positional relationship established for an immediately preceding one of the distance movements, certain orientation parameters, the maximum movement value and the determined signal strength of the locating signal in the current positional relationship. Target coordinates are accepted and a target position, based on the target coordinates, is included as part of the current positional relationship. The position of the target is unconstrained with respect to system geometry. Steering command features are provided along with steering warnings.

Claims

1. In a system for tracking a boring tool within an underground region in which system the boring tool is configured for transmitting a dipole locating signal axially coincident with an elongation axis of the boring tool, a method comprising the steps of:

determining a starting positional relationship including the boring tool and a receiving position at which the dipole locating signal is to be monitored such that the receiving position is generally ahead of the boring tool;

moving the boring tool in a direction generally forward through the ground in a series of distance movements such that each distance movement is less than a maximum movement value;

for each distance movement making up a first sequence in said series of distance movements, using at least measured values of the locating signal taken at the receiving position to determine a forward distance from the boring tool to an orthogonal plane defined normal to the elongation axis and including the receiving position; and

when, for a particular one of the first sequence of the distance movements, the forward distance is determined to be less than the maximum movement value, thereafter monitoring the dipole locating signal during a second sequence in the series of said distance movements in a predetermined way which detects a specific one of the distance movements concluding the second sequence of distance movements during which the boring tool crosses said plane.

2. The method of claim 1 further comprising the steps of:

for each distance movement in a third sequence of said distance movements, continuing to monitor the dipole locating signal in said predetermined way for another crossing of said plane and determining a rearward distance from the boring tool to said plane now located behind the boring tool; and

when the rearward distance determined following one of the distance movements concluding the third sequence is greater than said maximum movement value, for each distance movement making up a fourth sequence of said series of distance movements, using at least measured values of the locating signal taken at the receiving position to confirm that the rearward distance is greater than said maximum movement value.

3. The method of claim 2 further comprising the steps of:

obtaining target coordinates toward which the boring tool is intended to be directed during said series of distance movements;

determining a relative positional relationship including the boring tool and the receiving position for each of said distance movements; and

establishing a target position of the target coordinates relative to the boring tool as part of said relative positional relationship for each of said distance movements.

4. The method of claim 3 wherein the step of obtaining the target coordinates includes the step of accepting the target coordinates specified relative to the receiving position.

5. The method of claim 4 including the step of defining a global coordinate system in said region having an origin on the elongation axis of said boring tool corresponding to a point source of the dipole locating signal and having three orthogonally opposed axes, and the step of establishing the target position relative to the boring tool includes the step of using the target coordinates specified relative to the receiving position to determine the target position in global coordinates.

6. The method of claim 3 further comprising the step of:

displaying at least the target position and boring tool relative to one another for use in guiding the boring tool to the target position.

7. The method of claim 6 wherein said displaying step includes the step of showing the target and boring tool on a display screen having the boring tool offset from the target position as if viewed looking forward along the elongation axis of the boring tool.

8. The method of claim 3 wherein the dipole locating signal is receivable at the receiving position when the receiving position is within a dipole receiving range of the boring tool and wherein said target position is established up to approximately the dipole receiving range from the target position.

9. The method of claim 3 wherein the dipole locating signal is receivable at the receiving position when the receiving position is within a dipole receiving range of the boring tool, said method including the step of arranging the boring tool in the starting positional relationship and the target location such that an intended path of the boring tool is longer than said dipole receiving range.

10. The method of claim 1 wherein an axial plane is defined by the elongation axis of the boring tool and the receiving position and, during the second sequence of distance movements, the step of monitoring the dipole locating field in said predetermined way includes the step of determining flux components of the dipole locating signal in said axial plane to identify the boring tool having passed the receiving position with respect to said orthogonal plane.

11. The method of claim 10 wherein an orthogonal pair of axes ξ

and ζ

are included in said axial plane such that the ξ

axis is coincident with the elongation axis of the boring tool and the ζ

axis is normal thereto in said axial plane and where b_ξ

and b_ζ

are components of the dipole locating field along the ξ and

ζ

axes, respectively, said method including the step of monitoring b_ζ

to identify the boring tool having passed the receiving position with respect to the elongation axis of the boring tool.

12. The method of claim 11 wherein the step of monitoring b_ζ

detects the passage of the boring tool beyond the receiving position based on a change in the sign of b_ζ

.

13. The method of claim 11 wherein, during said second sequence of distance movements, said forward distance is determined, at least in part, using an angle α

defined as;

$\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\alpha <br><br>}=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2}$

where r is a radial distance between the boring tool and the receiving position.

14. The method of claim 1 wherein for each distance movement a third sequence of said distance movements after the boring tool crosses said orthogonal plane, continuing to monitor the dipole locating signal in said predetermined way for another crossing of said orthogonal plane while using measured values of the dipole locating signal and said certain orientation parameters to confirm that a rearward distance from the boring tool to said orthogonal plane now located behind the boring tool is less than the maximum movement value.

15. The method of claim 14 wherein an axial plane is defined by the elongation axis of the boring tool and the receiving position and an orthogonal pair of axes ξ

and ζ

are included in said axial plane such that the ξ

axis is coincident with the elongation axis of the boring tool and the ζ

axis is normal thereto in said axial plane and where b_ξ

and b_ζ

are components of the dipole locating field along the ξ and

ζ

axes, respectively, said method including the step of monitoring b_ζ

in a way which identifies the boring tool having crossed the orthogonal plane.

16. The method of claim 15 wherein the step of monitoring b_ζ

detects the passage of the boring tool across the orthogonal plane based on a change in the sign of b_ζ

.

17. The method of claim 15 wherein, during said third sequence, the rearward distance of the receiving position behind the boring tool is determined, at least in part, using an angle γ

defined as;

$\tan <br><br>\left(\mathrm{\gamma <br><br>}\right)=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},<br><br>\mathrm{\alpha <br><br>}=\mathrm{\gamma <br><br>}+180<br><br>\mathrm{°<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2},$

where angle α

is defined between the elongation axis of the boring tool and a line extending from the boring tool to the receiving position and r is a radial distance between the boring tool and the receiving position.

18. The method of claim 14 wherein, after the rearward distance determined following one of the distance movements in the third sequence is greater than said maximum movement value, for each distance movement making up a fourth sequence of said distance movements, using at least measured values of the locating signal taken at the receiving position and said certain orientation parameters to confirm that the rearward distance remains greater than said maximum movement value.

19. The method of claim 18 wherein, during said fourth sequence the rearward distance of the receiving position behind the boring tool is determined, at least in part, using an angle γ

defined as;

$\tan <br><br>\left(\mathrm{\gamma <br><br>}\right)=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},<br><br>\mathrm{\alpha <br><br>}=\mathrm{\gamma <br><br>}+180<br><br>\mathrm{°<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2},$

where angle α

is defined between the elongation axis of the boring tool and a line extending from the boring tool to the receiving position and r is a radial distance between the boring tool and the receiving position.

20. In a system for tracking a boring tool within an underground region in which system the boring tool is configured for transmitting a dipole locating signal axially coincident with an elongation axis of the boring tool, an apparatus comprising:

first means for determining a starting positional relationship including the boring tool and a receiving position at which the dipole locating signal is to be monitored such that the receiving position is generally ahead of the boring tool;

second means for moving the boring tool in a direction generally forward through the ground during a series of distance movements such that each distance movement is less than a maximum movement value;

third means for using at least measured values of the locating signal taken at the receiving position, for each distance movement making up a first sequence in said series of distance movements, to determine a forward distance from the boring tool to an orthogonal plane defined normal to the elongation axis and including the receiving position and for terminating the first sequence when, for a particular one of the distance movements in the first sequence, the forward distance is determined to be less than the maximum movement value; and

fourth means for monitoring the dipole locating signal during a second sequence in the series of said distance movements in a predetermined way which detects a specific one of the distance movements concluding the second sequence during which the boring tool crosses said plane.

21. The apparatus of claim 20 further comprising:

fifth means for continuing to monitor the dipole locating signal in said predetermined way, corresponding to each distance movement in a third sequence of said distance movements for another crossing of said plane and for determining a rearward distance from the boring tool to said plane now located behind the boring tool and for terminating the third sequence when the rearward distance determined following one of the distance movements is greater than said maximum movement value; and

sixth means for using at least measured values of the locating signal taken at the receiving position for each distance movement in a fourth sequence of said series of distance movements, to confirm that the rearward distance is greater than said maximum movement value.

22. The apparatus of claim 21 further comprising:

seventh means for (i) obtaining target coordinates toward which the boring tool is intended to be directed during said series of distance movements, (ii) determining a relative positional relationship including the boring tool and the receiving position for each of said distance movements, and (iii) establishing a target position of the target coordinates relative to the boring tool as part of said relative positional relationship for each of said distance movements.

23. The apparatus of claim 22 wherein said seventh means is configured for accepting the target coordinates specified relative to the receiving position.

24. The apparatus of claim 23 wherein said seventh arrangement is further configured for defining a global coordinate system in said region having an origin on the elongation axis of said boring tool corresponding to a point source of the dipole locating signal and having three orthogonally opposed axes, and for establishing the target position relative to the boring tool using the target coordinates specified relative to the receiving position to determine the target position in global coordinates.

25. The apparatus of claim 22 further comprising display means configured for displaying at least the target position and boring tool relative to one another for use in guiding the boring tool to the target position.

26. The apparatus of claim 25 wherein said display means is configured for showing the target and boring tool on a display screen having the boring tool offset from the target position as if viewed looking forward along the elongation axis of the boring tool.

27. The apparatus of claim 22 wherein the dipole locating signal is receivable at the receiving position when the receiving position is within a dipole receiving range of the boring tool and wherein said seventh arrangement is configured for using the target position established up to approximately the dipole receiving range from the target position.

28. The apparatus of claim 22 wherein the dipole locating signal is receivable at the receiving position when the receiving position is within a dipole receiving range of the boring tool and wherein said first means and said seventh means are configured for cooperatively establishing the starting positional relationship and the target position, respectively, such that an intended path of the boring tool is longer than said dipole receiving range.

29. The apparatus of claim 20 wherein an axial plane is defined by the elongation axis of the boring tool and the receiving position and said fourth means is configured for monitoring the dipole locating field in said predetermined way during the second sequence of distance movements, at least in part, by determining flux components of the dipole locating signal in said axial plane to identify the boring tool having passed the receiving position with respect to said orthogonal plane.

30. The apparatus of claim 29 wherein an orthogonal pair of axes ξ

and ζ

are included in said axial plane such that the ξ

axis is coincident with the elongation axis of the boring tool and the ζ

axis is normal thereto in said axial plane and where b_ξ

and b_ζ

are components of the dipole locating field along the ξ and

ζ

axes, respectively, wherein said fourth means monitors b_ζ

to identify the boring tool having passed the receiving position with respect to the elongation axis of the boring tool.

31. The apparatus of claim 30 wherein said fourth means detects the passage of the boring tool beyond the receiving position based on a change in the sign of b_ζ

.

32. The apparatus of claim 30 wherein said fourth means is configured for determining said forward distance, during said second sequence of distance movements, using an angle α

defined as;

$\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\alpha <br><br>}=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2}$

where r is a radial distance between the boring tool and the receiving position.

33. The apparatus of claim 20 including fifth means for continuing to monitor the dipole locating signal in said predetermined way, for each distance movement in a third sequence of said distance movements after the boring tool crosses said orthogonal plane, to detect any potential crossing of said orthogonal plane using measured values of the dipole locating signal and said certain orientation parameters and to confirm that a rearward distance from the boring tool to said orthogonal plane, now located behind the boring tool, is less than the maximum movement value and for terminating the third sequence when the rearward distance is greater than the maximum movement value.

34. The apparatus of claim 33 wherein an axial plane is defined by the elongation axis of the boring tool and the receiving position and an orthogonal pair of axes ξ

and ζ

are included in said axial plane such that the ξ

axis is coincident with the elongation axis of the boring tool and the ζ

axis is normal thereto in said axial plane and where b_ξ

and b_ζ

are components of the dipole locating field along the ξ and

ζ

axes, respectively, said fifth means is configured for monitoring b_ζ

in a way which identifies the boring tool having crossed the orthogonal plane.

35. The apparatus of claim 34 wherein said fifth means detects the passage of the boring tool across the orthogonal plane based on a change in the sign of b_ζ

.

36. The apparatus of claim 34 wherein, during said third sequence, the rearward distance of the receiving position behind the boring tool is determined by said fifth means, at least in part, using an angle γ

defined as;

$\tan <br><br>\left(\mathrm{\gamma <br><br>}\right)=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},<br><br>\mathrm{\alpha <br><br>}=\mathrm{\gamma <br><br>}+180<br><br>\mathrm{°<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2},$

where angle α

is defined between the elongation axis of the boring tool and a line extending from the boring tool to the receiving position and r is a radial distance between the boring tool and the receiving position.

37. The apparatus of claim 33 further comprising fifth means for executing a fourth sequence of the distance movements using at least measured values of the locating signal taken at the receiving position and said certain orientation parameters to confirm that the rearward distance remains greater than said maximum movement value.

38. The apparatus of claim 37 wherein, during said fourth sequence, the rearward distance of the receiving position behind the boring tool is determined by said fifth means, at least in part, using an angle γ

defined as;

$\tan <br><br>\left(\mathrm{\gamma <br><br>}\right)=\frac{\left(-3<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{9<br><br>b_{\mathrm{\xi <br><br>}}^2+8<br><br>b_{\mathrm{\zeta <br><br>}}^2}\right)<br><br>\mathrm{sign}<br><br>\left(b_{\mathrm{\zeta <br><br>}}\right)}{2<br><br><br><br>b_{\mathrm{\zeta <br><br>}}<br><br>},<br><br>\mathrm{\alpha <br><br>}=\mathrm{\gamma <br><br>}+180<br><br>\mathrm{°<br><br>},\mathrm{and}$ $\frac{1}{r^3}=-\frac{1}{4}<br><br>b_{\mathrm{\xi <br><br>}}+\sqrt{\frac{9}{16}<br><br>b_{\mathrm{\xi <br><br>}}^2+\frac{1}{2}<br><br>b_{\mathrm{\zeta <br><br>}}^2},$

where angle α

is defined between the elongation axis of the boring tool and a line extending from the boring tool to the receiving position and r is a radial distance between the boring tool and the receiving position.