Borepath analyzer

Abstract

A tracker used to analyze a desired borepath prior to horizontal directional drilling operations. The tracker analyzes an amount of interference present at a plurality of different frequencies at multiple locations along the borepath and maps a plot of the interference at the different frequencies. The lower the point on the plot, the less interference present at that frequency at the location analyzed. The tracker summarizes the overall interference along the desired borepath for the different frequencies analyzed and will recommend a preferred frequency. An operator may program the beacon prior to boring operations to emit a beacon signal at the preferred frequency. The operator may also tune the tracker to receive the preferred frequency. The tracker and beacon may then communicate during boring operations at the preferred frequency in order to detect the position of the beacon underground relative to the tracker.

Description

FIELD

The present invention relates generally to the field of locating underground objects, and in particular to locating and tracking a beacon within the field of operation of a horizontal drilling machine.

SUMMARY

The present invention is directed to a method for tracking a beacon. The method comprises the steps of placing a tracker at a first location, measuring an amount of interference present at each of a plurality of different frequencies at the first location, and determining a preferred frequency based on the amount of interference. The method further comprises the steps of programming the beacon to emit a beacon signal at the preferred frequency, placing the beacon below ground, and determining a location of the beacon relative to the tracker by detecting the beacon signal at the preferred frequency.

The present invention is also directed to a method for analyzing a plurality of different frequencies present along a borepath. The method comprises the steps of measuring an amount of interference at each of the plurality of different frequencies at a first location using a tracker, measuring the amount of interference present at each of the plurality of different frequencies at a second location using the tracker, averaging the amount of interference present at each of the plurality of different frequencies at the first location and at the second location in order to determine a preferred frequency to tune the tracker to during a horizontal drilling operation, and tuning the tracker to the preferred frequency during the horizontal drilling operation.

The present invention is also directed to a tracker for locating a beacon. The tracker comprises a first antenna to detect a beacon signal at a plural of different frequencies, and a processor configured to determine a preferred frequency based on a summary of interference present at each of the plurality of different frequencies. The processor is also configured to tune the antenna to the preferred frequency. The beacon emits the beacon signal at the preferred frequency, and the processor is adapted to process the beacon signal emitted at the preferred frequency detected by the first antenna and determine a location of the beacon relative to the tracker.

The present invention is further directed to a horizontal boring system. The system comprises a rotary drilling machine, a drill string, a downhole tool, and a tracker. The drill string has a first end and a second end, the first end is operatively connectable to the rotary machine to drive rotation of the drill string. The second end of the drill string is connected to the downhole tool. The downhole tool comprises a beacon that emits a beacon signal at a plurality of different frequencies. The tracker is used for location of the beacon. The tracker comprises a first antenna to detect the beacon signal, and a processor configured to determine a preferred frequency for the beacon signal based on a summary of interference present at each of the plurality of different frequencies. The processor is adapted to process the beacon signal detected by the first antenna and determine a location of the beacon relative to the tracker.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a horizontal directional drilling system for drilling a horizontal borehole and a tracking system built in accordance with the present invention.

FIG. 2 is a perspective view of a tracker constructed in accordance with the present invention.

FIG. 3 is a perspective view of the tracker exemplifying a plot formed on a visual display on the tracker in accordance with the present invention.

FIG. 4 is a flowchart depicting a method to analyze a desired borepath in accordance with the present invention.

DESCRIPTION

The horizontal directional drilling industry traditionally uses walk-over tracking techniques to follow the progress of a bore, to find the surface location immediately above the drill bit, and to determine the depth of the drill bit from that surface location. The primary tracking tools are a subsurface transmitter, also called a beacon, and a hand-carried surface receiver assembly. The beacon, located in or very near a downhole boring tool, generally emits a beacon signal at a specific frequency. The beacon signal can be used for both location and communication with the above ground receiver assembly. However, there may be instances where interference from outside sources emitting signals interrupts this communication.

Turning now to the figures, and first to FIG. 1, a horizontal directional drilling system for use with the present invention is shown. FIG. 1 illustrates a boring machine 12 sitting on the around surface 14. FIG. 1 also illustrates a desired borepath 16. A drill string 18 is shown connected to a downhole tool 20 at a first end 22 and the boring machine 12 at a second end 24. The downhole tool 20 comprises a drill bit 26 and a beacon 28. In operation, the drill bit 26 will bore underground and advance the downhole tool 20 and drill string 18 forward along the desired borepath 16. The boring machine 12 will add a plurality of pipe sections to the drill string 18 as the downhole tool 20 advances farther along the desired borepath 16.

Continuing with FIG. 1, an operator 30 holding a tracker 32 is also shown. During boring operations, the beacon 28 contained within the downhole tool 20 will emit a beacon signal (not shown) at a designated frequency. The tracker 32 is adapted to receive the beacon signal and determine the location of the downhole tool 20 underground relative to the tracker. Based on the determined location of the downhole tool 20 underground, the operator 30 can determine whether or not the downhole tool is boring along the desired borepath 16 or if steering corrections need to be made.

Turning now to FIG. 2, the tracker 32 is shown in greater detail. The tracker 32 comprises a receiver assembly 34 and a first antenna 36. The receiver assembly 34 comprises a housing 38. The tracker 32 may also comprise a second antenna 40 and a third antenna (not shown). The antennas 36 and 40 may be spaced apart on a horizontal frame 42, as shown in FIG. 2, or the antennas may be in a vertical plane with the receiver assembly 34, as shown in FIG. 1. The housing 38 comprises a visual display 44 and a plurality of input devices 46. A processor 47 may be disposed within the housing 38. The receiver assembly 34 may also comprise a handle 48.

The antennas 36 and 40 shown in FIG. 2 are adapted to detect the beacon signal emitted from the beacon 28 (FIG. 1) at the designated frequency. Once the antennas 36 and 40 detect the beacon signal, they send an antenna signal (not shown) to the receiver assembly 34. The processor 47 of the receiver assembly 34 interprets the antenna signal and identifies the location of the beacon 28 (FIG. 1) underground relative to the receiver assembly. The beacon 28 is capable of emitting the beacon signal at a plurality of different frequencies. Similarly, the antennas 36 and 40 are capable of detecting the beacon signal at the plurality of different frequencies. For example, the beacon 28 may transmit the beacon signal at 1,000 Hz, 2,000 Hz, 3,000 Hz, or 30,000 Hz, depending on which frequency the operator 30 has programmed the beacon to emit.

The antennas 36 and 40 are also adapted to detect alternative magnetic field sources being emitted at one of the plurality of different frequencies within range of the tracker 32. Objects emitting magnetic field sources within range of the tracker 32, such as power lines, gas lines, railroads, etc., may interrupt the communication between the beacon 28 and the tracker. This interruption is referred to as interference. The amount of interference present at the different frequencies may vary depending on what frequency the alternative magnetic field source is emitting its signal. One frequency may have a much greater amount of interference present while a second frequency may have a much lower amount of interference present. The lower the amount of interference present, the more effectively the tracker 32 can communicate with the beacon 28. Thus, one frequency may be more effective than other frequencies at certain locations along the desired borepath 16 for the beacon 28 and the tracker 32 to communicate during drilling operations. Based on this, the tracker 32 of the present invention is configured to analyze the amount of interference present at the plurality of different frequencies along the course of the desired borepath 16 prior to starting boring operations and determine the preferred frequency at which the beacon 28 (FIG. 1) should communicate with the tracker 32.

Turning back to FIG. 1, to analyze the borepath, the operator 30 must first ensure that there are no beacons 28 on in the area to disrupt the interference analysis. The tracker 32 is then placed in “analyze mode.” This may be initiated by pressing one of the input devices 46 on the tracker 32 (FIG. 2). The operator 30 will start by analyzing a first location (I) along the desired borepath 16. To do this, the operator 30 holds the tracker 32 over the first location (I) and tells the tracker to analyze the first position (I). This may be initiated by pressing one of the input devices 46 on the tracker 32. The tracker 32 will then measure a type of interference and an amount of noise at each of the plurality of different frequencies present and selected to be analyzed at the first location (I), such as 1,000 Hz, 2,000 Hz, 3,000 Hz, or 30,000 Hz frequencies.

Referring now to FIG. 3, once the operator 30 begins analyzing the first location (I) (FIG. 1), a plot 50 may begin on the visual display 44 of the tracker 32 indicating the interference or relative noise floors present at the plurality of different frequencies analyzed. The lower a point on the plot 50 for a specific frequency, the deeper that frequency can be detected without interference. The most effective frequency or frequencies to emit the beacon signal during boring can be determined by the lowest points on the plot 50. Once the operator 30 is done analyzing the first location (I), the operator may move and perform the same analysis on a second location (II) and a third location (III) (FIG. 1). The operator 30 may analyze as many locations as needed along the desired borepath 16. The plot 50 will be created at each location analyzed along the borepath 16. The analysis of the multiple locations will be stored within the processor 47 (FIG. 2) of the tracker 32 along with the GPS coordinates of the multiple locations. The required power level to complete the analysis of the entire desired borepath 16 may not be known by the tracker 32. Prior to analyzing, the operator 30 may select the appropriate power level for the analysis based on the job requirements,

Referring now to both FIGS. 1 and 3, once the operator 30 has finished measuring the interference present along the desired borepath 16 using the tracker 32, the operator may tell the tracker 32 to summarize the amount of interference present at the different frequencies for the entire borepath. This may be initiated by pressing one of the input devices 46 on the tracker 32. The summary provides the operator 30 with the average amount of interference for each frequency measured along the entire borepath and provides the operator with the recommended frequency at which to emit the beacon signal from the beacon 28 and to tune the tracker 32 to during horizontal drilling operations. Since the amount of interference may vary at different locations along the borepath 16, the summary may recommend more than one frequency to use during drilling operations. The operator 30 may determine the preferred frequency or frequencies based on the provided recommendation. However, the preferred frequency may vary from the recommended frequency or frequencies based on the specific needs of the boring operation. After forming the summary of interference, the tracker 32 may also recommend one of a plurality of different digital modulation schemes, such as OOK, FSK, PSK, etc., to operate on based on the amount of interference at each of the plurality of different frequencies.

Continuing with FIG. 1, the beacon 28 may be programmed to emit only one preferred frequency during the entire boring operation, or if using a multiple frequency beacon, the beacon may be programmed to emit two or more different preferred frequencies while boring. However, the beacon 28 may only emit one of the two or more preferred frequencies at a time. Therefore, the operator 30 may toggle back and forth between the different frequencies depending on which frequency is preferred at certain locations along the borepath 16. The beacon 28 may be manually set to emit the preferred frequency or frequencies prior to boring operations or it may be set using Bluetooth prior to boring operations if the beacon is capable of Bluetooth communication. Once the beacon 28 is programmed, the beacon, along with the downhole tool 20, may be placed underground and boring operations may begin.

Turning now to FIG. 4, a flowchart depicting a method to analyze the desired borepath 16 is shown. To start, the operator 30 will place the tracker 32 in “analyze mode” by pressing one of the input devices 46 on the tracker (step 100). The operator 30 will then analyze the first location (I) by holding the tracker 32 over the first location (I) and pressing one of the input devices 46 to initiate the analysis (step 102). The tracker 32 will analyze the first location (I) by measuring the amount of interference and noise present at each of the selected frequencies at the first location (I) (step 104). Following this analysis, the tracker 32 will create a plot 50 on the visual display 44 identifying the amount of interference present at the selected frequencies at the first location (I) (step 106). The tracker 32 will save this data along with the GPS coordinates of the first location (I) (step 108).

Continuing with FIG. 4, the operator 30 will analyze as many additional locations along the desired borepath 16 as necessary by repeating steps 102 through 108 at each additional location (step 110). The tracker 32 will then average all of the data collected and create a summary of interference (step 112). The tracker 32 will then provide the operator 30 with the recommended frequency or frequencies at which to emit the beacon signal and to tune the tracker to during horizontal drilling operations; the operator 30 will then determine the preferred frequency or frequencies based on the recommended frequency (step 114).

After the operator 30 determines the preferred frequency or frequencies, the operator will program the beacon 28 to emit the preferred frequency or frequencies (step 116). The beacon 28 is then placed underground (step 118) and the boring machine 12 may begin boring operations (step 120). While boring, the beacon 28 will emit the preferred frequency based on the preferred frequency at the location of the beacon (step 122). Once the beacon 28 emits the preferred frequency, the operator 30 may detect the location of the beacon relative to the tracker 32 (step 124). After locating the beacon 28, the operator 30 will ensure that the downhole tool 20 is continuing along the desired borepath 16, and if necessary, the operator 30 will make steering corrections before continuing to bore (step 126). The operator 30 may continue detecting the beacon 28 at the preferred frequency until boring of the desired borepath 16 is complete (step 128).

Prior to completing boring operations, the operator 30 will determine if a second or different frequency is preferred to detect the beacon 28 as the beacon moves to a new location along the desired borepath 16 (step 130). If the second frequency is not preferred at the new location, the operator 30 will continue detecting the beacon signal at the original preferred frequency while boring operations continue (steps 126 and 124). If the second frequency is preferred, the operator 30 will change the beacon 28 to emit the second preferred frequency. The operator 30 will then detect the beacon 28 relative to the tracker 32 using the second preferred frequency while boring operations continue. The operator 30 will toggle between the different preferred frequencies as needed until boring operations are completed (step 132). The operator 30 may perform step 130 as many times as needed along the desired borepath 16.

The present invention provides a tracking system with the ability to analyze the different frequencies the beacon 28 is capable of emitting and determine which frequency has the least amount of interference present at certain locations along the borepath. The present invention may also be used to assist the operator 30 in creating a borepath plan. Before beginning drilling operations, it is often desirable to create a plan for the path of the drill bit 26 to ensure the resulting bore will pass through certain waypoints or will avoid certain known obstacles. The plan is often compared to the actual path of the bore as the progress of the drill bit 26 is tracked. The operator 30 may compare the plan with the analysis of the desired borepath described in steps (100-114) with reference to FIG. 4. This analysis may be used by the operator 30 to note locations on the plan where the beacon 28 will need to emit a different frequency.

The plan may be loaded onto a display unit (not shown) located at the boring machine 12. The display unit may be programmed to notify the operator 30 when the bore has reached a location on the plan that requires the operator 30 to command the beacon 28 to emit the locating signal at a different frequency.

The present invention may also be used to assist the operator 30 in determining what depth to drill the bore. For example, if the tracker 32 detects a large amount of interference or a high noise floor at one frequency, the operator 30 may choose to drill more shallow or deeper in that area to avoid the interference. These determinations may also be incorporated into the plan for drilling the bore.

Various modifications can be made in the design and operation of the present invention without departing from its spirit. Thus, while the principal preferred construction and modes of operation of the invention have been explained in what is now considered to represent its best embodiments, it should be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

Claims

1. A method for configuring a beacon for use in horizontal directional drilling operations, the method comprising: using a tracker to measure a magnetic field interference on multiple frequencies at a first above-ground location;moving the tracker to a second above-ground location;using the tracker to measure the magnetic field interference on multiple frequencies at the second above-ground location;selecting a first transmission frequency in response to the magnetic field interference measured at the first above-ground location;selecting a second transmission frequency in response to the magnetic field interference measured at the second above-ground location; andconfiguring the beacon adapted for incorporation into a drill string to transmit on both the first and the second transmission frequency prior to lowering the beacon underground, wherein the beacon transmits at the first transmission frequency proximate the first above-ground location and transmits at the second transmission frequency proximate the second above-ground location during a horizontal boring operation.

2. The method of claim 1 wherein the first transmission frequency and the second transmission frequency are the same.

3. The method of claim 1 wherein the first transmission frequency is different from the second transmission frequency.

4. A method for tracking a beacon along a desired borepath, the method comprising: using a tracker to measure a magnetic field interference on multiple frequencies at a first above-ground location;moving the tracker to a second above-ground location;using the tracker to measure the magnetic field interference on multiple frequencies at the second above-ground location;selecting a first transmission frequency in response to the magnetic field interference measured at the first above-ground location;selecting a second transmission frequency in response to the magnetic field interference measured at the second above-ground location;configuring the beacon to transmit a beacon signal on the first transmission frequency and on the second transmission frequency prior to lowering the beacon underground;detecting the beacon signal with the tracker at the first transmission frequency proximate the first above-ground location to determine a first position of the beacon relative the tracker;moving the beacon below ground from proximate the first above-ground location to proximate the second above-ground location; anddetecting the beacon signal with the tracker at the second transmission frequency proximate the second above-ground location to determine a second position of the beacon relative the tracker.

5. The method of claim 4 further comprising: averaging the magnetic field interference on multiple frequencies at the first above-ground location and at the second above-ground location in order to determine an average amount of magnetic field interference.

6. The method of claim 4 wherein the first transmission frequency and the second transmission frequency are the same.

7. The method of claim 4 wherein the first transmission frequency is different from the second transmission frequency.

8. The method of claim 4 further comprising using a processor to recommend one of a plurality of different digital modulation schemes for the beacon to operate on based on the magnetic field interference on multiple frequencies.

9. An assembly comprising: a beacon configured to generate a magnetic field signal at a first frequency at a first location below ground and at a second frequency at a second location below ground during a horizontal boring operation; anda tracker comprising: a first antenna configured to receive the magnetic field signal generated by the beacon on the first frequency at the first location and on the second frequency at the second location; anda processor configured to select the first and the second frequency from a plurality of frequencies based on the amount of interference detected by the first antenna on each frequency prior to lowering the beacon underground,wherein the processor is configured to process the magnetic field signal received by the first antenna to determine a position of the beacon underground relative to the tracker at the first and the second location during the horizontal boring operation.

10. The assembly of claim 9 wherein the beacon is incorporated into a drill string underground.

11. The assembly of claim 10 wherein the drill string is attached to a horizontal directional drilling machine located above-ground.

12. The assembly of claim 9 wherein the tracker is portable.

13. The assembly of claim 9 wherein the beacon is located below-ground and the tracker is located above-ground.

14. The assembly of claim 9 further comprising a second antenna configured to receive the magnetic field signals generated by the beacon.