Multi-frequency in-ground locating signal frequency code identification and apparatus

• US 7,728,595 B2
• Filed: 05/08/2009
• Issued: 06/01/2010
• Est. Priority Date: 06/01/1999
• Status: Expired due to Term

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Brune, Guenter W.
• Primary Examiner(s): Patidar; Jay M
• Application Number:
  US12/463,189
• Publication Number:
  US 20090212777A1
• Time in Patent Office: 389 Days
• Field of Search: None
• US Class Current: 324/326
• 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

In a system in which a transmitter is moved through the ground in a region, the system including a locator for tracking the position of and/or guiding the transmitter as the transmitter moves through the ground, a locating signal is transmitted from the 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 using the locator. A selected one of the frequencies of the locating signal is indicated 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 the frequencies. An associated transmitter is also described.

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 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 using 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, 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.