Note: Descriptions are shown in the official language in which they were submitted.
i
CA 02456506 2005-06-20
Core Orientation Patent Application
Field of the Invention:
The invention relates to diamond drilling, and more specifically to methods
and tools to
obtain the original position and orientation of drill core after retrieval
from the ground.
Background of the Invention:
Core orientation is needed when mines do geotechnical surveys to assess
fracture patterns in
rock. >=!y determining the fracture density and orientation of the fractures,
companies are
better equipped to design a safe mine layout. Core orientation is done by
taking a number of
measmrements that allow the core's original position and orientation to be
known. This
requirEa at least a core rotation measurement, which can then be constrained
by a downhole
survey done after the hole is completed. Other techniques also get a dip
measurement in
addition to the rotation measurement, which can then be used to check the
survey done when
the hole is finished. Surveys that check the azimuth are not as reliable,
since magnetic ore
often nnakes these readings useless. Gyroscopes cannot be used while drilling
takes place
because of their sensitivity. ATV's (televiewers) are sometimes used to map
fractures
directly off the walls of the drill hole, but these instruments are costly,
require the surveyor to
be nearby, and the risk of losing the probe down the hole is significant.
Current methods of
core orientation are highly expensive, unreliable, or require high
maintenance.
On inclined drill holes, these disadvantages maybe overcome by using the
proposed,
robust electronic sensor attached to top of the core tube, which takes
readings at prescribed
times.
Brief Description of the Drawings:
Figure 1 is a Simplified Diagram of a Drill String, showing the basic
locations of the rods,
core tube, orientation tool and backend when in use.
Figure 2 is a Perspective View of the Sensor, showing the shape of the
orientation tool and
external features, including the reference line, threads and data transfer
points.
CA 02456506 2005-06-20
2
Figure 3 is a Perspective View of the Core Tube and Sensor Setup. This diagram
illustrates
the core tube assembly and the alignment of the reference lines.
Figure 4 is a Perspective View of the Display Unit showing the various
features of the
displa~r unit, used to store and display data obtained by the orientation
tool.
Summary of the Invention:
The purpose of this invention is to provide a low-cost, accurate and reliable
core orientation
method for inclined holes. The system consists of an orientation device,
specialized core
tube, display unit and, where necessary, a customized drill rod extension. The
orientation
device's components are: electronic sensor, clock, thermometer, power source,
programming
and memory circuitry, shock absorbers and data transfer system, all encased in
a standard
diameter core tube extension. This orientation device is attached to the top
of the specialized
core tube during drilling. The electronic sensor component (a 3-axis
accelerometer in the
preferc~ed embodiment) takes readings used to give the core rotation data. The
orientation
device can also give a core inclination measurement for each core run which
may be used for
other survey purposes. The specialized core tube is aligned with the sensor,
to facilitate
accurate marking of the retrieved core. The display unit is a computing
device, which
retrieves the core orientation data from the orientation device and stores it
on a memory card.
The optimum setup for the system uses: 1) radio transmissions between the
orientation device
and di;>play unit when readings are taken; and 2) a 3-axis accelerometer for
the orientation
device. A backup method for data transfer and battery recharge is also
included, where the
orientation device is plugged into the display unit. This system would cost
less than scribing,
and be more accurate than the other methods available for inclined holes.
Detailed Description of Invention:
Core drilling (Figure 1), is accomplished by the outer tube (4), which has a
steel and diamond
bit screwed to the bottom (5). Within the outer tube, the inner tube, also
called the core tube
(3) rests just above the drill bit (5). The core tube becomes filled with core
as the drill bit on
the outer tube cuts through the rock. During this drilling, water is flushed
down the outer tube
(4) (about 20-40 liters/min). The inner tube (3) is usually about 3m long and
must be
CA 02456506 2005-06-20
retrieved after every 3m interval is drilled. To retrieve the core tube (3),
the core must be
broken from the bottom of the hole by pulling up on the drill string (4). A
retrieval tool is
lowered by wireline, which latches on to the backend (1) of the core tube (3)
so that the core
may be lifted from the hole.
For thc; proposed invention, the orientation device (2) has to be powered up
by attaching it to
a battery charger using the connection points at the bottom of the orientation
device. Once the
orientation device is working, the display unit (15) can be turned on and the
orientation
device (2) plugged into the display unit. The operator sets the clock on the
display unit (15)
and synchronizes the display (15) with the orientation device (2). If the
radio option is
available on the orientation device (2), this may be done without connecting
the orientation
device (2) to the display unit (I5).
The orientation device (2) is attached to the top of the core tube (3), below
the backend (1),
aligned with a clip (12) and lowered into the hole. Drilling commences once
the core tube is
at the bottom of the hole, and stops once three meters of core is drilled. In
the preferred
embodiment of the invention, the driller enters the depth of the hole on the
display unit (15)
and presses the "Take Reading" button. The display unit (15) transmits a
signal to the sensor
(2), which takes a reading and radios the measurements to the display unit
(15) for storage. In
case th.e radio system fails, the orientation device (2) also takes readings
every minute, which
may bc~ downloaded to the display unit (15) once the core tube (3) and
orientation device (2)
are retrieved. If this is the case, the driller must wait for a 2-minute
interval before breaking
the core and he must enter the depth and time the reading was taken on the
display unit (15).
The driller may then break the core and retrieve the core tube (3). The
orientation device
reference line {9) is in line with the core tube reference lines (13, 14)
marked at the top and
the bottom of the tube. The driller then marks the location of the reference
line (9) on the
core at the bottom of the core tube. With the reference line drawn on the
core, the rotation
measurement can be used to determine how the core was oriented in the hole.
The orientation device (2) components are (Figure 2): silicon 3-axis
accelerometer, clock,
thermometer, power source, programming and memory circuitry, shock absorbers
and data
transfer system, all encased in a standard diameter core tube extension
(likely NQ size, with a
SOmm internal diameter)(8). The top and bottom of the orientation device (2)
are threaded (7,
CA 02456506 2005-06-20
4
11 ) allowing the orientation device (2) to attach to the top of the core tube
(3) and the bottom
of the backend (1). The power source provides the electricity for the other
orientation device
(2) components. The accelerometer measures the orientation of the earth's
gravitational force
with re;spect to the orientation device. The accelerometer is aligned with a
reference line (9)
etched into the outside of the orientation device, so that the rotation
readings obtained are
with respect to this reference line. The clock measures the time at which the
accelerometer.
took the reading. The reading the thermometer measures is used to make
temperature
adjustrnents for the accelerometer reading. The programming and circuitry
process the raw
accelerometer data into meaningful rotation and inclination data. The memory
circuitry keeps
this data in storage until no longer necessary. The data transfer system uses
either radio
communications, or uses the backup connectors (10) on the bottom of the
orientation device
(2) to communicate the data to the display unit. Two of the connection points
(10) on the
bottom are used for charging the battery or capacitor in the orientation
device before use. The
shock .absorbers help protect the electronic components from shocks when the
core tube is
dropped down the outer tube. The orientation device (2) attaches to the top of
the core tube
(3), just below the backend (1). The orientation device is sealed so that it
may go down drill
holes up to 3km deep without water leaking into the electronics.
The display unit (15) components are (Figure 4): large LCD with back light
(16), radio
transmitter and receiver, keypad with large buttons (17), sealed memory card
port (18),
battery storage, port for radio antenna (22), port for external power source
(21, preferably
12V, L>C), port for orientation device connectionldata transfer (19), and
internal circuitry for
data input, storage and output. The display unit is extremely rugged and is
weathe;rproof/waterproof. Buttons include: onloff, numbers 0 to 9, decimal
point, delete,
enter, hake reading, take test, download, light, clock, and synchronize. The
LCD displays both
data and instructions for operation of the device, in English, French or
Spanish. All ports are
sealed and protected by plugs and covers to keep them clean and dry.
The core tube (3) is a standard size and design (about 3m long, Scm internal
diameter, screw
thread: at either end), apart from having reference lines 20 mm long and 0.5
mm wide etched
at the top (13) and the bottom (14), and having a method of aligning the core
tube reference
line with that of the orientation device (12). Other core tube sizes are
envisioned depending
CA 02456506 2005-06-20
on the drilling requirements. The original product is for NQ size drilling,
but HQ and other
sizes are also planned.
An ad<litional drill rod extension (a custom length of drill rod with screw
threads at both
ends) accompanies the orientation device to compensate for the extra length of
the core tube
(3) and orientation device (2) assembly.
If the radio was not used, the driller must connect the orientation device (2)
to the display
unit (15)(which is synchronized to the orientation device) to download the
correct reading.
The readings are stored on internal and removable memory cards, so that if
power is lost, the
data can be retrieved later. The removable memory card can be given to the
geotechnician
responsible for orienting the core. The geotechnician can make all his
measurements before
or after using the orientation device data to properly orient his readings. If
he makes his
measurements with regard to the reference lines drawn on the core, his
readings can be
transformed in the computer. Otherwise, he can use a modified protractor and
draw the
oriented top line on the core and make readings off of that.
It will be apparent that the invention has been described with reference to
certain details of
constnzction and these details should be interpreted as examples and not as
limitations to the
scope ~~f the invention.
