Multi-Frequency Boring Tool Locating System and Method

• US 20090212777A1
• Filed: 05/08/2009
• Published: 08/27/2009
• Est. Priority Date: 06/01/1999
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Brune, Guenter W.
• Granted Patent: US 7,728,595 B2
• Time in Patent Office: Days
• US Class Current: 324/329
• CPC Class Codes: E21B 47/02 Determining slope or direction
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: 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
• 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

Arrangements, apparatus and associated methods are described for use in a multi-frequency boring tool locating system. The boring tool includes a transmitter for transmitting a locating signal at two or more selectable frequencies. One set of above ground procedures may be applied to the transmitter in order to change the frequency of the boring tool transmitter. Another set of procedures is applicable for changing the frequency during below ground drilling operations, for example, by subjecting the boring tool to a predetermined roll orientation sequence. An enhanced portable locator operates in a manual or automatic mode to receive locating frequency information transmitted from the boring tool transmitter including frequency updates. Boring tool transmitter, as well as above ground locator shutdown/restart procedures are described relating to multi-frequency operation. A tone detector is described which implements one or more digital match filters.

Claims

1. In a system in which a transmitter is moved through the ground in a region, said system including a locator for tracking the position of and/or guiding the transmitter as the transmitter moves through the ground, a method comprising:

transmitting a locating signal from the transmitter using a transmitter that is selectively operable at a current one of at least two frequencies for use in tracking the transmitter by receiving the locating signal at the frequency with the locator; and

indicating a selected one of said frequencies of the locating signal to the locator using a frequency code that is produced by a locating signal frequency control arrangement which forms part of the transmitter, which frequency code can individually identify each of said frequencies.

2. The method of claim 1 wherein said method further comprises:

detecting a command issued to the transmitter in a predetermined way to change the selected locating frequency to a different one of said locating frequencies, as compared to the current frequency, using said frequency control arrangement;

modulating said frequency code for the different frequency of the locating signal at least once on the locating signal for designating the selection of the different one of the locating frequencies to the locator; and

thereafter, switching the current one of said locating frequencies of the transmitter to the different one of the locating frequencies, as a new current frequency.

3. The method of claim 2 wherein detecting said command issued in said predetermined way includes detecting a roll sequence to which said transmitter is subjected.

4. The method of claim 1 wherein indicating the selected frequency includes transmitting said frequency code from the transmitter on a carrier frequency that is separate from said locating signal.

5. The method of claim 1 further comprising:

detecting a command issued to the transmitter in a predetermined way to change the selected frequency to a different one of said frequencies using said locating signal frequency control arrangement;

switching the current frequency of the locating signal to the different one of the frequencies using the locating signal frequency control arrangement; and

sending at least one indication to the locator, responsive to detection of said command, designating the different one of the locating frequencies that is selected including the frequency code that is specific to the different frequency.

6. In a system including a transmitter which is moved through the ground in a region, said system further including a locator for tracking the position of and/or guiding the transmitter using the locating signal, said transmitter comprising:

a first arrangement for transmitting a locating signal at a current one of at least two locating frequencies for receipt by the locator; and

a locating signal frequency control arrangement for indicating a selected one of the locating frequencies of the locating signal to the locator using the frequency code which can individually identify each of said frequencies.