Underground utility installation tension monitoring arrangement and method

• US 5,961,252 A
• Filed: 10/20/1997
• Issued: 10/05/1999
• Est. Priority Date: 10/20/1997
• Status: Expired due to Term

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Digital Control Incorporated
• Inventors: Mercer, John E., Hambling, Peter H.
• Primary Examiner(s): Taylor, Dennis L.
• Application Number:
  US08/953,923
• Time in Patent Office: 715 Days
• Field of Search: 405/168.3, 405/177, 175/53, 175/50, 73/862.44, 73/800
• US Class Current: 405/175
• CPC Class Codes: E21B 47/007 Measuring stresses in a pipe string or casing for locating blocked portions of pipes E21B47/09
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency
• CPC Class Codes: E21B 7/28 Enlarging drilled holes, e.g. by counterboring

Abstract

An improved method of operating a drilling system for purposes of installing an underground line and associated apparatus are disclosed. The drilling system includes a drill rig which is positionable at a drilling site and a drill string which is configured for extension by the drill rig such that the drill string is extendable to a predetermined location in a way which forms a pilot bore and which is further configured for retraction, such that one end of a line may be attached to the drill string at the predetermined location and pulled through the pilot bore from the predetermined location to the drill rig as the drill string is retracted. The improvement comprises monitoring tension levels in the line during retraction which tension levels are caused by the force of retraction on the line and transmitting the tension levels to an above ground location for use in establishing the condition of the line as it is installed underground. The associated apparatus includes means for monitoring tension levels in the line caused by the force of retraction on the line and means for transmitting the tension levels to the above ground location.

Claims

1. In a method of operating a drilling system for the purpose of installing an underground line, said system including a drill rig which is positionable at a drilling site and a drill string which is configured for extension by said drill rig such that the drill string is extendable in a way which forms a bore and which is further configured for retraction, such that one end of a line may be attached to an end of the drill string in a predetermined way and pulled through said bore to the drill rig as the drill string is retracted, the improvement comprising the steps of:

a) during said retraction, monitoring tension levels in said line which tension levels are caused by the force of said retraction on the line; and

b) transmitting said tension levels to an above ground location using an electromagnetic signal for use in establishing the condition of said line as it is installed underground.

2. The improvement according to claim 1 further comprising the steps of:

c) transmitting an electromagnetic locating signal from said end of the drill string to which the line is attached to said above ground location for use in establishing an underground position of said one end of the line.

3. The improvement according to claim 2 wherein said tension levels are transmitted to the above ground location by modulating said tension levels onto said electromagnetic locating signal.

4. The improvement according to claim 2 wherein said line may be subjected to a maximum tension level without incurring damage, the improvement further comprising the step of:

d) ceasing to retract said drill string if said maximum tension level is monitored during the retraction of the drill string such that the line is undamaged due to excessive retraction tension.

5. The improvement according to claim 4 further comprising the step of:

e) using said locating signal, determining a splicing location of said one end of said line along said pilot bore at which retraction ceased; and

f) exposing said one end of the line such that a new line may be attached to said drill string which new line may be retracted by the drill string through the remaining portion of said pilot bore to said drill rig such that the new line and said line may be spliced at said splicing position so as to form said underground line extending from said predetermined location to said drill rig.

6. The improvement according to claim 1 wherein said system includes a boring tool positioned on said drill string during said drilling operation and said drill rig includes display means for displaying at least one orientation parameter relating to said boring tool during the drilling operation, the improvement further comprising:

c) configuring said display means such that said tension levels are displayed in place of said orientation parameter during pulling of said line.

7. In a drilling system for use in installing an underground line, said system including a drill rig which is positionable at a drilling site and a drill string which is configured for extension by said drill rig such that the drill string is extendable in a way which forms a bore and which is further configured for retraction, such that one end of a line may be attached to an end of the drill string in a predetermined way and pulled through said bore to the drill rig as the drill string is retracted, the improvement comprising:

a) means for monitoring tension levels in said line which tension levels are caused by the force of said retraction on the line; and

b) means for transmitting said tension levels to an above ground location using an electromagnetic signal for use in establishing the condition of said line as it is installed underground.

8. The improvement according to claim 7 further comprising:

c) means for transmitting an electromagnetic locating signal from said end of the drill string to which the line is attached to said above ground location for use in establishing an underground position of said one end of the line.

9. The improvement according to claim 8 wherein said tension level transmitting means includes means for modulating said tension levels onto said electromagnetic locating signal such that the electromagnetic locating signal also serves to transmit said tension levels.

10. The improvement according to claim 7 wherein said line may be subjected to a maximum tension level without incurring damage, the improvement further comprising:

c) means for establishing that the retraction tension level has reached said maximum tension level such that retraction may be stopped prior to damaging said line.

11. The improvement according to claim 10 further comprising:

e) display means for providing an audio and/or visual warning when said maximum tension level has been reached.

12. The improvement according to claim 7 further comprising:

c) display means for providing an audio and/or visual display representative of said tension levels at said above ground location.