APPARATUS AND METHOD FOR DETERMINING POSITION OF DRILLING TOOL DURING DRILLING

Abstract

An apparatus and method of determining the position of a drilling tool during drilling is provided. The apparatus includes a magnetic source mounted to a rotating drilling tool and at least two magnetometers, which are located outside a drilled hole. Sensing data of a rotating magnetic field is transmitted from the magnetometers to a control unit provided with a position calculation algorithm. The control unit is also provided with position data of the magnetometers and a reference position of the drilling tool. The control unit compares the received sensing data when the drilling tool is in the reference position and when being moved to a new position. Phase angles are then detected from the sensing data. The algorithm utilizes the phase angles and the known positions of the magnetometers and the reference point when calculating the changed position.

Claims

1. An apparatus for detecting change of position of a drilling tool of a rock drilling rig during drilling when the drilling tool is rotated around its longitudinal drilling axis, the apparatus comprising: at least one magnetic source mounted to the rotatable drilling tool and configured to generate rotating magnetic field, and wherein a direction of axis of the rotating magnetic field deviates from the drilling axis; at least two magnetometers configured to sense the rotating magnetic field generated by the magnetic source; at least one control unit configured to receive sensing data from the magnetometers and being configured to examine the rotating magnetic field; and at least a first magnetometer and a second magnetometer, which are both located external relative to the drilling tool, wherein the control unit is provided with data on position and orientation of the magnetometers, the control unit being provided with reference data including first reference sensing data of the first magnetometer, and second reference sensing data of the second magnetometer, when the magnetic source is located at a known reference position, and wherein the control unit is configured to compare first sensing data of the first magnetometer to the first reference sensing data for detecting a first phase angle between them, and correspondingly, to compare second sensing data of the second magnetometer to the second reference sensing data for detecting a second phase angle, and the control unit being configured to calculate a position change of the magnetic source relative to the known reference position in response to the detected phase angles and the known position of the magnetometers.

2. The apparatus as claimed in claim 1, wherein the control unit is configured to examine the received sensing data by determining maximum strengths of the received magnetic field values and to determine a corresponding rotation angle of the magnetic source relative to the examined magnetometer, and the control unit being configured to determine the phase angles between the reference sensing data and any new sensing data by comparing the determined rotation angles of the detected maximum strength values.

3. The apparatus as claimed in claim 1, wherein the magnetometers are located on a rock surface surrounding the drill hole being drilled.

4. The apparatus as claimed in claim 1, wherein the control unit is provided with data on an advanced distance of the magnetic source inside the drilled hole, the control unit being configured to calculate three dimensional position data on the magnetic source in response to the detected position and the received data on the advance distance.

5. The apparatus as claimed in claim 1, wherein the control unit is provided with sensing data from the magnetometers at several measuring points locating at different advance distances of the magnetic source inside the drilled hole, the control unit being configured to compare the calculated position data of the several measuring points and is configured to determine bending of the drilling tool in response to detected deviations in the position data.

6. The apparatus as claimed in any claim 1, wherein the control unit is provided with data on coordinates of the magnetometers and the reference position in a work site coordinate systems, the control unit being configured to calculate coordinates of the magnetic source in the work site coordinate system.

7. The apparatus as claimed in claim 1, wherein the control unit is configured to calculate position of a face surface of the drilling tool in response to input position data of the magnetic source relative to the face surface, whereby the position of the drilling tool is examined as the position of the face surface.

8. The apparatus as claimed in claim 1, wherein the control unit is provided with a processor configured to execute a position detection algorithm the execution of which is configured to calculate the position of the magnetic source in response to the received sensing data of the magnetometers and the input reference data and position data.

9. The apparatus as claimed in claim 1, wherein the control unit is configured to execute the position determination without comparing strength of the detected magnetic fields.

10. The apparatus as claimed in claim 1, wherein the magnetic source is a permanent magnet.

11. The apparatus as claimed in claim 1, wherein the magnetic source is mounted to a drill bit located at a distal end of the drilling tool.

12. A rock drilling rig, comprising: a movable carrier; at least one drilling boom connected movably to the carrier and equipped with a rock drilling unit, wherein the rock drilling unit includes a feed beam and a rock drilling machine supported movably on the feed beam; and at least one apparatus according to claim 1 for determining a position of the drilling tool connectable to the drilling unit; and wherein the apparatus is in accordance with the previous claims 1-11.

13. A method of determining position of a drilling tool of a rock drilling rig during drilling operation, the method comprising: rotating the drilling tool around its longitudinal drilling axis during the drilling and feeding the drilling tool axially forward in an advance direction; detecting a change of position of the drilling tool during the drilling by means of an apparatus having at least one magnetic source mounted to the rotating drilling tool and at least two magnetometers; generating a rotating magnetic field by rotating the magnetic source together with the drilling tool); sensing the rotating magnetic field by means of the magnetometers and producing sensing data; generating reference data by rotating the drilling tool at a known reference position and detecting a first reference sensing data by means of a first magnetometer and a second reference sensing data by means of a second magnetometer; comparing first sensing data of the first magnetometer to the first reference sensing data and detecting a first phase angle therebetween and correspondingly, comparing second sensing data of the second magnetometer to the second reference sensing data and detecting a second phase angle; and calculating a changed position of the magnetic source relative to the reference position on the basis of the detected phase angles and the position data of the magnetometers and the reference position.

14. The method as claimed in claim 13, further comprising: sensing an advanced distance of the magnetic source inside the drilled hole during the drilling; repeating the position measurement at several measuring points having different depths in the drill hole; and comparing the calculated positions of the drilling tool at the several measuring points and determining straightness of the drill hole in response to the comparison.

15. A computer program product having program code means configured to execute the method of claim 13 when executed by a computer or a data processing device.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0071] FIG. 1 is a schematic side view of a rock drilling rig.

[0072] FIG. 2 is a schematic diagram presenting components of the disclosed apparatus.

[0073] FIG. 3 is a schematic side view of a drilling tool and its components provided with magnetic sources.

[0074] FIG. 4 is a schematic side view of a drilling tool at a bottom of a drill hole.

[0075] FIG. 5 is a schematic side view of a magnetic source surrounded by means of non-ferromagnetic protection material.

[0076] FIG. 6 is a schematic diagram showing a control unit intended for executing position detection.

[0077] FIG. 7 is a schematic top view of a measuring arrangement comprising two magnetometers and a magnetic source mounted to a rotating drilling tool.

[0078] FIG. 8 is a schematic graph of magnetic field measurements taken by a magnetometer at a reference position and at a changed position of the magnetic source.

[0079] FIG. 9 is a schematic side view of a measuring arrangement for detecting drill hole straightness.

[0080] FIG. 10 is a schematic side view showing an alternative mounting arrangement for magnetometers.

[0081] FIG. 11 is a schematic representative graph of magnetic field measurements and determination of a phase angle.

[0082] For the sake of clarity, the figures show some embodiments of the disclosed solution in a simplified manner. In the figures, like reference numerals identify like elements.

DETAILED DESCRIPTION

[0083] FIG. 1 shows a rock drilling rig 1 for drilling drill holes 2. The rock drilling rig 1 includes a movable carrier 3 and one or more drilling booms 4 connected to the carrier 3. The drilling boom 4 is provided with a drilling unit 5 having a feed beam 6 and a rock drilling machine 7 supported movably on it. A drilling tool 8 is connectable to the rock drilling machine 7 and may be rotated in a direction R around drilling axis 9 by means of a rotation device of the rock drilling machine 7.

[0084] At a distal end of the drilling tool 8 is a drill bit 10. The rock drilling machine 7 may have a percussion device for generating impact pulses to the drilling tool 8. The percussion device may be located either in connection with the drilling machine 7 or at a distal end portion of the drilling tool, whereby the percussive rock drilling may be top hammer drilling or down-the-hole drilling. A further alternative is that the drilling is rotary drilling without percussion. The rock drilling machine 7 is fed in the direction F during the drilling by means of a feed device, which is not shown in FIG. 1.

[0085] The rock drilling rig 1 of FIG. 1 is intended for vertical surface drilling and may be equipped with the apparatus as disclosed herein. However, the solution of FIG. 1 is only one drilling application. The disclosed solution may also be utilized in other drilling solutions, such as in long hole drilling, face drilling, bench drilling, etc.

[0086] FIG. 2 discloses an apparatus 11 for positioning sensing of a drilling tool. The apparatus 11 includes one or more control units CU for analysing sensing data received from two or more magnetometers 12. The apparatus 11 further includes one or more magnetic sources 13 mounted to a rotatable drilling tool. The apparatus 11 may also be provided with depth sensing means 14 for determining an advance distance of the magnetic source inside a drill hole.

[0087] FIG. 3 discloses a drilling tool 8, which may include several drilling components connected to each other. The drilling tool 8 may have one or more drilling rods 15 or tubes and a drill bit 10. Between the rod 15 and the drill bit 10 may be an adapter piece 16. At least one of the components 15, 16, 10 is provided with at least one magnetic source 13. The magnetic source 13 is mounted so that axis of magnetic field 17 is transverse to drilling axis 9 of the drilling tool 8. It is possible to use several magnetic sources 13 in one component or provide several components with them.

[0088] FIG. 4 discloses a distal end part of a drilling tool 8. Between drill bit 10 and drill rod 15 is an adapter piece 16 made of non-ferromagnetic material and having a permanent magnet 13. The magnet 13 is then close to a face of the drill bit and a bottom 18 of a drill hole 2. The distance between the magnet 13 and the bottom 18 is known and the position of the drill hole bottom 18 may thereby be sensed by the disclosed solution.

[0089] FIG. 5 discloses that around a magnetic source 13 may be a protective material 19, which may be of non-ferromagnetic material. The protective material 19 may dampen mechanical forces directed to magnetic source 13 and may also encapsulate it against harsh conditions occurring inside the drill hole. The protective material 19 may also participate in fastening of the magnetic source 13.

[0090] FIG. 6 discloses a control unit CU having a processor 20 for executing a position detection program 21 input to the control unit CU. The control unit CU further includes memory means 22 for storing programs and data, and data communication means 23 for communicating with servers and other control units, such as with a drilling control unit of a rock drilling rig or with a mine control system.

[0091] The control unit has input means 24 for receiving position and orientation data on magnetometers 25. Reference data 26 including data on the reference position 27 of the magnetic source and reference sensing data 28 of the magnetometers is also input to the control unit before executing actual position measures. When the position of the drilling tool is tracked sensing data produced by the magnetometers 29 is input to control unit CU. Also, data on the advance distance of the tracked magnetic source 30 may be input.

[0092] The control unit analyses the input data and outcomes of the analyses and calculations executed by the processor 20 are transmitted through output means 31 to desired systems, servers and control units. The control unit CU may produce position data on the drilling tool 32, data on drill hole straightness or bending of the drilling tool 33, control commands for steering and controlling the drilling process 34 and updates 35 to drilling patterns, excavation plans and charging plans, for example.

[0093] FIG. 6 further discloses that rotation data 41 of the drilling tool and the included magnetic source may be sensed and input to the control unit CU. The rotation data 41 may be determined by means of separate sensing devices, which are located in connection with the drilling unit. The rotation data 41 of the drilling is known by the system since rotation is one control parameter of the drilling process. However, the rotation data 41 may also be determined by analyzing sensing results received from the magnetometers.

[0094] FIG. 7 illustrates the disclosed measuring principle, wherein the drilling tool 8, provided with a magnetic source 13, is rotated and rotation angles A can be sensed by a first magnetometer 12a and a second magnetometer 12b. Reference data needed in the calculation can be produced by rotating the drilling tool 8 at a known reference position 27. Then the rotating magnetic field is sensed by the magnetometers 12a and 12b and first reference sensing data 28a and second reference sensing data 28b are generated. The reference data may be generated before the actual drilling is initiated.

[0095] During normal drilling actual sensing data 29a, 29b is produced by the magnetometers 12a, 12b. If the drilling tool 8 changes its position from the known reference point 27 in the examined plane and moves in direction T to a new position 36, then a first phase angle B exists between the first reference sensing data 28a and the actual first sensing data 29a, and correspondingly a second phase angle C exists between the second reference sensing data 28b and the actual second sensing data 29b. This is due to changed alignment between the first magnetometer 12a and the magnetic source 13, and correspondingly between the second magnetometer 12b and the magnetic source 13.

[0096] Further, positions 25a, 25b of the magnetometers 12a, 12b are known by the tracking system, whereby position data of the new position 36 can be calculated. The actual calculation is based on normal trigonometry, which is well known by one skilled in the art and is therefore not described in detailed herein.

[0097] In FIG. 7 lines 28a-28c and 29a-29b are used only to illustrate the sensing data. The actual sensing data comprises signals and has a typical sine wave form as it is disclosed in FIGS. 8 and 11. Thus, FIG. 7 is a simplified presentation for improving understanding the disclosed solution.

[0098] FIG. 8 discloses graphs of the first reference sensing data 28a and the first actual sensing data 29a. The magnitude or strength H of the sensed magnetic field in relation to the rotation angle A of the drilling tool is illustrated. As can be noted, the reference data 28a and the sensing data 29a can be illustrated as sine waves. When examining the sine waves, for example peak values 37a and 37b, it can be noted that there is a shift in the peak values 37a, 37b. In other words, the curves have a phase difference. The phase difference corresponds to the first phase angle B. The phase angle C can be illustrated and determined in a similar manner

[0099] FIG. 9 discloses a measuring principle for determining bending of a drill hole 2. The drilling tool 8 is positioned at a start point of a drill hole and this point can be used as a reference point. The positioning system of the rock drilling rig knows the accurate position of the drilling tool at the start point. Magnetometers 12a and 12b are mounted on a rock surface 38 and they may be located at different distances L1 and L2 from the drilling tool 8. Positions of the magnetometers 12a, 12b and the drilling tool 8 positioned at the reference point can be determined in a work site coordinate system 39, for example. When the drilling begins, the position of the drilling tool 8 is determined by examining rotating magnetic field generated by a magnetic source 13. Simultaneously, the advance distance of the drilling tool 8 is sensed by means of sensor 14. When the position measurements are executed at several measuring points Mp1-Mp3, positions at different advance distances Ad1-Ad3 are detected. On the basis of the obtained data, straightness of the drill hole 2 can be examined in a control unit CU.

[0100] FIG. 10 discloses a solution, wherein magnetometers 12a, 12b are connected to a drilling unit 5 by means of arms 40. The arms 40 may be movable and may include joints.

[0101] FIG. 11 discloses readings or output of a magnetometer 12b in function to a rotation angle A of the magnetic source. A reference sinus wave 28b and actual sensing sinus wave 29b have a different phase angle C. The phase angle C can be determined despite the fact that amplitudes H1 and H2, i.e., strengths of the magnetic fields at the reference point and at the new changed location, are different. Thus, FIG. 11 illustrates that the position determination can be done without examining strength values of the magnetic fields. In other words, values of magnetic flux density E, i.e., sensed Tesla (T), have no significant importance to the determination of the phase angles.

[0102] Although the present embodiments have been described in relation to particular aspects thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred therefore, that the present embodiments be limited not by the specific disclosure herein, but only by the appended claims