WO2004055325A1

WO2004055325A1 - Drilling head position display

Info

Publication number: WO2004055325A1
Application number: PCT/AU2003/001690
Authority: WO
Inventors: Timothy Gregory Hamilton Meyer; Scott Christopher Adam
Original assignee: CMTE Development Ltd
Current assignee: CMTE Development Ltd
Priority date: 2002-12-18
Filing date: 2003-12-18
Publication date: 2004-07-01
Anticipated expiration: 2005-06-18
Also published as: AU2002953435A0

Abstract

The position of an underground drilling head is represented on a visual display unit (1) by way of separate displays of two planes, typically a plan view (2) and a sectional side view (6). A trajectory line (5, 7) representing the path of the drilling head is displayed in each plane against relevant information such as mine roadways (3) or desired optimum position limits represented by envelope lines (8, 9). This enables an operator to make simple real time decisions in performing steering operations.

Description

DRILLING HEAD POSITION DISPLAY Field of the Invention

This application relates to a method of displaying information on the position of an underground drilling head to a drill operator. Background of the Invention

Drilling operations in mines and other underground borehole drilling operations use many different types of known borehole drilling techniques. Conventional drilling heads use a mechanical drill bit to cut through a rockface, typically guided by a bent sub. Other applications use fluid drilling heads typically having a number of nozzles from which issue high pressure water jets that break up and erode a rock face. With fluid drilling heads, the drilling head can be connected to the surface via a flexible hose. This is advantageous because it allows tight-radius drilling operations. In tight-radius drilling, the drilling head is fed down a vertical well and then bent around a tight radius to carry out drilling operations in a substantially horizontal trajectory. Usually, coal seams are located in horizontal planes relative to the surface and tight-radius drilling, using a fluid drilling head, is an effective method of drilling multiple boreholes to drain gas and water from the coal seams.

While fluid drilling heads allow greater manoeuvrability than conventional drilling heads, they can be difficult to control due to the flexible nature of the hose. Directional control is important in many applications, including drilling drainage boreholes for methane gas. In such applications, it is critical to achieve an optimum pattern of drainage bores and to ensure that the bores are accurately placed to pass through proposed roadway locations in a mine.

One solution to the problem of directional control of fluid drilling heads is to provide the fluid drilling head with a biasing force and control its direction by rotation of the hose (and hence the drilling head), to utilise the bias for directional control (see International patent application PCT/AU03/01391).

However, even with improved fluid drilling heads of this type, there is a need to improve further the steering of drilling heads in practice. It has been found that a major part of the problem in controlling fluid drilling heads is operator error. Fluid drilling systems can penetrate the rock at speeds in excess of four metres per minute, and due to the flexibility of the hose can turn through ninety degrees within a few metres drilling. Traditionally, the position of the drilling head is fed to an operator as numerical data. The drill operator, having been presented with data on the drilling head's present orientation and distance must then calculate the position before selecting the roll (clockface) angle of the drilling head to direct it in its desired trajectory. Often, the drill operator is required to make drill direction and roll angle selections in a short space of time, reacting to local geological conditions at the drilling head. In summary, the drill operator needs to process the present position of the drilling head in three dimensions, visualise the optimum trajectory of the drilling head and select the requisite roll angle to maintain the drilling head on its optimum trajectory. In such circumstances, operator error is virtually inevitable. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. It is an object of the present invention in its preferred form to display information on the position of a drilling head in such a way as to minimise operator error. Summary of the Invention Accordingly, the present invention provides a method of displaying information on the position of an underground drilling head, said method including transmitting to a computer data which can be used to determine the position of the drilling head in predetermined first and second distinct planes; and displaying on a visual display unit a first position of the drilling head viewed against the first plane in the drilling head's underground environment, and a second position of the drilling head viewed against the second plane in the drilling head's underground environment; wherein the first and second positions of the drilling head are plotted as separate trajectory lines on the visual display unit.

Where the term "plane" is used throughout this specification it is typically referring to a flat plane, although the term is also used to encompass a curved plane which may be appropriate for displaying the information on the position of the drilling head in certain situations, such as those in which the seam being drilled lies in a curved plane.

The first and second planes referred to above are "distinct" in the sense that they are separated by a significant angle to enable the three dimensional location of the drilling head to be determined by a resolution f om each plane. In practice, the first and second planes are typically mutually orthogonal, and more typically would comprise horizontal and vertical planes. It will however be appreciated that there are many instances, for example when drilling a significantly inclined seam, that the "horizontal" plane would in fact be inclined and the "vertical" plane may then either be a true vertical or arranged to be perpendicular to the inclined base plane. Hereinafter in this specification the terms "horizontal" and "vertical" position of the drilling head are generally referred to with reference to corresponding horizontal and vertical planes, as this is the most common application, but it will be appreciated that the invention is equally applicable when the planes are not horizontal and vertical, and are not necessarily mutually orthogonal.

The present invention recognises the importance of presenting the drill operator with intelligible information on the drilling head's present position, its past position and its desired future position. With detailed knowledge of the drilling head's present, past and desired future trajectory, presented in a comprehensible form, the drill operator is better placed to make informed decisions on future steering operations.

Real-time data which can be used to determine the horizontal and vertical position of the drilling head may be transmitted to a computer at the surface using any suitable technique. Typically, data is transmitted to the surface on an alternating voltage signal using a phase shift method. An alternating voltage frequency (e.g. 10 Hz) is supplied to the high pressure hose connected to the back of the drill and is referenced to earth. A receiver box on the surface is used to measure the residual voltage potential between the hose end situated on the surface and the earth. Such an arrangement allows wireless transmission of data to the surface, although other means of transmitting positional data to the surface are included within the scope of the present invention, (see, for example, US 4,806,869 or US 5,467,083).

The data itself need not be absolute positional data. It maybe calculated from knowledge of the drilling head's starting position, its direction and speed. For example, the drilling tool may include a suite of sensors for measuring drill orientation - pitch (inclination), azimuth (yaw) and roll (clockface) angle. The drilling tool may, optionally, include sensors for detecting the proximity of the roof or floor of the seam and for measuring the vibration of the drilling tool. The drill orientation values may be transmitted to the surface at predetermined intervals, for example, every 1-20 seconds, or typically every 7 seconds. Once the drilling head orientation values have been transmitted to the surface, these values may be used to calculate the trajectory of the drill using a "dead-reckoning" method. Dead-reckoning trajectory determination involves building a trajectory curve out of multiple straight line segments. Each segment has a direction determined by the averaged values of azimuth and inclination for a predetermined (e.g. 7 second) period, and a length equal to the distance drilled during that predetermined period. In this way, a computer can calculate the trajectory from the horizontal and vertical positions of the drilling head..

Once the computer has received (or calculated) the position of the drilling head, this position is displayed on a visual display unit by updating horizontal and vertical trajectory lines. The horizontal position of the drilling head is displayed as a trajectory line against a plan view of the drilling head's underground environment; the vertical position of the drilling head is displayed as a trajectory line against a sectional side view of the drilling head's underground environment. The presentation of positional data by the computer in this way is advantageous from an operational point of view. The drill operator can see the actual position of the drilling head relative to the desired trajectory line. This position gives the operator a much better "feel" for the direction in which the head must be steered.

Preferably, the present invention is used in connection with drilling heads operated in mines. Accordingly, the plan view is preferably a plan of a mine and the sectional side view is a sectional side view of the mine.

Preferably, the sectional side view includes a pair of envelope lines which represent the optimum vertical position limits of the drilling head. The trajectory lines are fixed lines which may represent, for example, the optimum path of the trajectory between the roof and floor of a coal seam. The envelope lines provide further assistance to the drill operator in creating a mental image of the vertical position of the drilling head relative to its optimum trajectory. This, in turn, assists the drill operator in steering the drilling head.

Preferably, the visual display unit displays additional information relating to underground geological data, such as geological data in a mine. The geological data may be superimposed onto the plan and/or sectional side view of the mine, or it may be displayed on a separate part of the visual display unit. Preferably, the geological data includes the roof position, the floor position, the location of dykes and/or the location of faults. These data are preferably superimposed onto the plan and/or sectional side views. Hence, the drill operator is presented with this information visually, relative to the horizontal and vertical trajectories of the drilling head. This helps the drill operator to anticipate a trajectory aimed at a particular geological feature (e.g. a coal seam roof) and, if necessary, change the drilling head trajectory well in advance of drilling into such a feature.

Preferably, the visual display unit displays additional information on planned or existing underground infrastructure. This may be, for example, in the form of existing or planned roadways. Typically, mine roadways are displayed on the plan view. Preferably, the visual display unit displays additional information on the roll

(clockface) angle, yaw (azimuth) and/or pitch (inclination) of the drilling head. These may be displayed as numerical data or as vectors, usually on a separate part of the visual display unit. This additional information on the orientation of the drilling head is useful for steering. In the case of dead-reckoning trajectory determination, all these data will have been transmitted to the computer. Hence, the drilling head would require no extra sensors.

Preferably, the drilling head is a fluid drilling head. Fluid drilling heads are used advantageously in connection with the present invention, because they are generally difficult to control and require regular monitoring and readjustment of trajectory. Brief Description of the Drawings

A preferred form of the invention will now be described with reference to the following drawing, in which:

Fig. 1 shows the screen of a visual display unit displaying information according to the method of the present invention. Detailed Description of Preferred Embodiments of the Invention

A visual display unit 1 displays information from a computer on the position and orientation of a drilling head. In the upper right part of the visual display unit, there is provided a plan view 2 of a mine. The plan view 2 includes a plan of the various roadways 3 in the mine. The circle 4 represents the vertical borehole from a fluid drilling head in a tight-radius drilling operation. The trajectory line 5 represents the horizontal trajectory of the drilling head. This horizontal trajectory line 5 plots the horizontal movement of the drilling head in real-time. The plot is updated every seven seconds by using data transmitted to the computer from sensors on the drilling head. In a central part of the visual display unit, there is provided a sectional side view 6 of a mine. The trajectory line 7 represents the vertical trajectory of the drilling head. This vertical trajectory line 7 plots the vertical movement of the drilling head in realtime and, like the horizontal trajectory line 5, is updated every seven seconds. Two fixed envelope lines 8 and 9 set the optimum upper and lower vertical position limits respectively for the drilling head which may relate, for example, to the roof and floor of a mining seam. Although the envelope lines 8 and 9 have been shown in the vertical plane projection, they are equally applicable to other planes in various situations.

These position limits are typically determined beforehand by knowledge of the coal seam that is intended to be drilled, from survey data. This information can then be fed into the computer for calculation and display of the envelope lines 8 and 9 which would typically correspond to the roof and floor respectively of a seam.

During drilling, the drill operator aims to keep the advancing vertical trajectory line 7 within the fixed vertical limits defined by lines 8 and 9 by appropriate steering of the drilling head.

The azimuth, pitch and roll of the drilling head are displayed numerically at 10, 11 and 12 respectively. These assist the drill operator in performing steering operations.

The section 13 of the visual display unit is used to display further operational instructions to the drill operator. It will, of course, be appreciated that the present invention has been described by way of example only and that modifications of detail maybe made within the scope of the invention.

Claims

Claims:-

1. A method of displaying information on the position of an underground drilling head, said method including transmitting to a computer data which can be used to determine the position of the drilling head in predetermined first and second distinct planes; and displaying on a visual display unit a first position of the drilling head viewed against the first plane in the drilling head's underground environment, and a second position of the drilling head viewed against the second plane in the drilling head's underground environment; wherein the first and second positions of the drilling head are plotted as separate trajectory lines on the visual display unit.

2. A method according to claim 1, wherein the first and second planes are substantially flat.

3. A method according to claim 2, wherein the first and second planes are substantially mutually orthogonal.

4. A method according to claim 3, wherein the first plane comprises a substantially horizontal plane, and the second plane comprises a substantially vertical plane.

5. A method according to any one of the preceding claims, wherein the drilling head's underground environment is a mine.

6. A method according to any one of the preceding claims, wherein the view of the position of the drilling head in at least one of the planes includes a pair of envelope lines which represent the optimum position limits of the drilling head in that plane.

7. A method according to any one of the preceding claims, wherein the visual display unit displays additional information relating to underground geological data.

8. The method according to claim 7, wherein the underground geological data includes the roof position of a mine, the floor position of a mine, the location of dykes and/or the location of faults.

9. The method according to any one of the preceding claims, wherein the visual display unit displays additional information on planned or existing underground infrastructure.

10. The method according to any one of the preceding claims, wherein the visual display unit displays additional information in the roll, yaw, and/or pitch of the drilling head.

11. The method according to any one of the preceding claims, wherein the drilling head is a fluid drilling head.

12. The method according to any one of the preceding claims, wherein the real-time position of a drilling head is displayed.