AU2016100133B4 - A method of determining a property of a bulk formation - Google Patents
A method of determining a property of a bulk formation Download PDFInfo
- Publication number
- AU2016100133B4 AU2016100133B4 AU2016100133A AU2016100133A AU2016100133B4 AU 2016100133 B4 AU2016100133 B4 AU 2016100133B4 AU 2016100133 A AU2016100133 A AU 2016100133A AU 2016100133 A AU2016100133 A AU 2016100133A AU 2016100133 B4 AU2016100133 B4 AU 2016100133B4
- Authority
- AU
- Australia
- Prior art keywords
- borehole
- tube
- measurement tool
- bulk formation
- drill rod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000005259 measurement Methods 0.000 claims abstract description 69
- 230000005855 radiation Effects 0.000 claims abstract description 36
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 235000019988 mead Nutrition 0.000 abstract 1
- 238000005755 formation reaction Methods 0.000 description 49
- 238000005553 drilling Methods 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- GUTLYIVDDKVIGB-OUBTZVSYSA-N Cobalt-60 Chemical compound [60Co] GUTLYIVDDKVIGB-OUBTZVSYSA-N 0.000 description 6
- 238000011835 investigation Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- TVFDJXOCXUVLDH-RNFDNDRNSA-N cesium-137 Chemical compound [137Cs] TVFDJXOCXUVLDH-RNFDNDRNSA-N 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Abstract
The present disclosure provides a method of determining a
density of a bulk formation that at least partially
5 surrounds a borehole. The method comprises providing a
borehole in the bulk formation with at least one drill rod
being positioned in the borehole. The drill rod comprises
a first tube and a second tube that surrounds the first
tube. The method further comprises inserting a measurement
10 tool into the first tube of the drill rod and moving the
measurement tool within the first tube along the borehole.
The method also comprises emitting radiation from the
measurement tool through the first and second tubes into
the bulk formation and detecting a radiation response from
15 the bulk formation through the first and second tubes. In
addition, the method comprises determining the density of
the bulk formation using the detected radiation response.
20
7395431_1 (GHMatters) P101139.AU.1 MEAD
Description
Field of the Invention
The present invention relates to a method of determining a
property, such as a density, of a bulk formation that
surrounds a borehole.
Background of the Invention
Mineral exploration often involves drilling boreholes into
bulk formations in a systematic manner and at preselected
locations. A borehole log is then obtained and provides
information that characterises the bulk formation
surrounding the borehole as a function of depth. In
mineral exploration, such as iron ore exploration,
suitable measurement instruments ("logging tools") are
lowered into the borehole after removal of drill rods and
then provide data about the bulk formation that surrounds
the borehole. For example, the provided information may be
used to calculate a density distribution of the bulk
formation as a function of depth and from which further
properties of the bulk formation can be determined.
The drilling of such boreholes in the iron ore industry
usually involves using reverse circulation drilling
systems. A reciprocating "hammer" is positioned in a drill
head of such a drilling system and forms rock chips. Drill
tubes for reverse circulation drilling have an inner and
an outer tube. Pressurised air is directed between the
inner and the outer tube to the drill head and is then
used to lift the generated rock chips (and water) within 18711099 1(GHMatters) P10 139.AU.1 the inner tube up to the ground surface. When the borehole is completed, the drill tubes are removed and the logging tool is then inserted into the borehole to obtain the information about the bulk formation that surrounds the borehole.
However, such boreholes often fill up with water below a certain depth, which often results in collapsing of the boreholes when the drill tubes are removed. It is then no longer possible to lower the logging tool along the entire length of the borehole. Consequently, only incomplete information about the surrounding bulk formation can then be provided.
There is need for improvement.
Summary of the Invention
In accordance with a first aspect of the present invention, there is provided a method of determining a property of a bulk formation that at least partially surrounds a borehole, the method comprising the steps of: providing the borehole in the bulk formation with at least one drill rod being positioned within the borehole as a result of providing the borehole, the at least one drill rod comprising a first tube and a second tube that surrounds the first tube; retaining the drill rod in place in the borehole; inserting a measurement tool into the first tube of the at least one drill rod and moving the measurement tool within the first tube along the borehole; emitting radiation from the measurement tool through the first and second tubes into the bulk formation; detecting a radiation through the first and second tubes; and determining the property of the bulk formation using the detected radiation response.
As in embodiments of the present invention the measurement
(the steps of inserting the measurement tool, emitting the
radiation and receiving the radiation) is conducted
through the inner and outer tubes, it can be avoided that
the borehole collapses and it is possible to determine the
property, such as a density, along the entire length of
the borehole.
The method may comprise forming the borehole in the bulk
formation. The drill rod may be one of a plurality of
drill rods that are coupled at end portions so as to form
a resultant longer drill rod. The step of inserting the
measurement tool into the first tube may comprise
inserting the measurement tool into the at least one drill
rod that has been used to form the borehole in the bulk
formation and is still positioned in the borehole.
The step of inserting the measurement tool into the inner
tube of the at least one drill rod may comprise lowering
the measurement tool along at least the majority or even
the entire length of the at least one drill rod. Further,
the steps of emitting the radiation and detecting the
radiation may be conducted during lowering or lifting the
measurement tool along at least the majority or even the
entire length of the at least one drill rod. The radiation
is typically radiation originating from a radioactive 18711099 1(GHMatters) P10 139.AU.1 decay and may be gamma radiation.
The at least one drill rod may be a reverse circulation
drill rod. The second tube may be an outer tube of the at
least one reverse circulation drill rod and the first tube
may be an inner tube of the at least one reverse
circulation drill rod.
The first and second tubes may be formed from steel, but
may alternatively also be formed from another suitable
metallic or non-metallic material. The first tube may have
an inner diameter of 30 - 70, 40 - 50 mm diameter, such as
48mm. The second tube may have an outer diameter 3 - 6, 4
- 5 inches, such as 4.5 inches.
The bulk formation may comprise an ore, such as iron ore.
In one embodiment the property is a density and the step
of determining the property of the bulk formation
comprises determining a density of the bulk formation in
the proximity of the borehole and along at least a portion
of the depth of the borehole.
The method may comprise lowering or lifting the
measurement tool within and along the first tube of the at
least one drill rod when at least a portion of the first
tube and/or at least a portion of a space between the
first tube and the second tube is filled with water.
Alternatively, the space between the first and second
tubes and/or an interior space of first tube may be at
least largely or entirely free from water. The step of
determining the property may comprise correcting a result
for an influence of the water.
The measurement tool may comprise a source of radioactive
radiation, such as gamma radiation. The source may be a
Cobalt 60 source, but may alternatively also be another
suitable source. In one specific embodiment the emitted
radiation is not collimated.
The measurement tool may comprise a detector for detecting
the radiation response from the bulk formation. The
detector typically is spaced apart from the source.
The detector may also be one of a plurality of detectors
that are spaced apart from each other and are positioned
along the housing of the measurement tool. The measurement
tool comprises in one specific embodiment of the present
invention a short space detector and a long space
detector. The short space detector may be spaced apart
from the source by approximately 100 to 500 mm, 150 to 400
mm, such as 350 mm. The long space detector may be spaced
apart from the source by approximately 250 to 700 mm, 400
to 600 mm, such as 550 mm.
The measurement tool may further comprise an elongated
housing having a portion in which the source for emission
of the radiation in radial directions and the detector or
the detectors for detection of radiation from radial
directions are positioned. The elongated housing may be
generally cylindrically shaped and may have an outer
diameter of 20 - 60, 30 - 50 or 40 - 50mm, such as 42mm.
In one specific embodiment of the present invention the
step of determining the property of the bulk formation
comprises calibrating. For example, calibrating may 18711099 1(GHMatters) P10 139.AU.1 comprise initially using the measurement tool in a reverse circulation rod that is positioned in an environment that has a known density distribution. Obtained measurement data can then be used to calibrate measurement data that has been obtained using the measurement tool in a bore hole surrounded by a bulk formation having an unknown density distribution.
Further, the method may comprise calculating a
compensation for compensating data obtained with the long
space detector using data obtained with the short space
detector.
Determining the property of the bulk formation may further
comprise correcting an obtained quantity for an influence
of water in the first and/or second tube.
In a second aspect of the present invention there is
provided a measurement tool for providing a quantity that
is indicative of a property of a bulk formation
surrounding a bore hole, the measurement tool comprising:
a source of radiation arranged for emission of the
radiation within the borehole;
a detector for receiving a radiation response from
the formation surrounding the borehole; and
a housing accommodating the source and the detector,
the housing having an outer diameter that is sufficiently
small such that the measurement tool can be lowered into
the interior of an inner tube of a reverse circulation
drill rod of a reverse circulation drill system.
The elongated housing of the measurement tool may be generally cylindrically shaped and may have an outer diameter of 20 - 60, 30 - 50 or 40 - 50mm, such as 42mm.
Brief Description of the Drawings
The present invention will now be described, by way of
example only, with reference to the accompanying drawings,
in which:
Figure 1 is a flow chart of a method in accordance
with an embodiment of the present invention;
Figures 2 (a) (b) and Figure 3 show a measurement
tool in accordance with an embodiment of the present
invention;
and
Figure 4 shows measurement data obtained using
methods in accordance with embodiments of the present
invention.
Description of Embodiments of the Present Invention
Embodiments of the present invention generally relate to a
method of determining a property, such as a density, of a
bulk formation that surrounds a borehole. The method
comprises drilling the borehole into the formation, which
may for example comprise iron ore. In this embodiment the
borehole is formed using a reverse circulation drilling
system. The reverse circulation drilling system comprises
drill rods that have inner and outer tubes.
After formation of the borehole, a measurement tool is
lowered into and along the inner tube of the reverse
circulation drilling system, which is not removed and left 18711099 1(GHMatters) P10 139.AU.1 in position when the measurement tool is lowered into the borehole.
The measurement tool comprises a source of radiation, such
as a Cobalt 60 source. The Cobalt 60 source emits gamma
radiation and the measurement tool also comprises a
detector that is spaced behind the source and arranged to
receive a radiation response from the bulk formation that
surrounds the borehole. The radiation is emitted by the
source and directed through the inner and outer tube of
the reverse circulation system. Further, the radiation
response from the formation received by the detector
propagated through the inner and outer tube of the reverse
circulation drill system.
The property, such as the density, of the bulk formation
is then determined using the detected radiation response.
Determination of the density as a function of the depth
may involve correcting the measurement data for an effect
of the inner and outer tubes, which will be described
further below in more detail.
The method in accordance with embodiments of the present
invention has the advantage that it is possible to
determine the property, such as the density, along the
entire depth of the borehole. As the reverse circulation
drill rods remain in place within the borehole, it can be
avoided that the borehole partially collapses, which is
often a problem with open boreholes, especially if the
boreholes are relatively deep and are at least partially
flooded with water.
Referring now to Figure 1 and 2, a method 10 and a
measurement tool 20 in accordance with specific
embodiments of the present invention are now described in
further detail. Figure 1 is a flow chart of the method 10
and Figures 2 (a) and (b) show a side and top views,
respectively, of the measurement tool 20 in accordance
with an embodiment of the present invention.
The method 10 comprises the initial step of drilling a
borehole into the bulk formation using a reverse
circulation drilling system. The measurement tool 20) is
than inserted into the borehole (step 14).
Step 16 of the method 10 comprises emitting radiation from
the measurement tool 20 through the first and second tubes
of the reverse circulation drill rods into the bulk
formation and during lowering or lifting of the
measurement tool 20. Further, the method 10 comprises
detecting a radiation response from the bulk formation
through the first and second tubes of the reverse
circulation drill rod during lowering or lifting of the
measurement tool 20.
Figure 2 (a) shows the measurement tool 20 having a
housing 22. The housing 22 is elongated and generally
cylindrically shaped. The measurement tool 20 comprises a
source of radiation 24, which in this embodiment a Cobalt
60 source. Further, the measurement tool 20 comprises a
short space detector 26 that is positioned at
approximately 250 mm or 350 mm behind the source 24. A
long space detector 28 is positioned at a distance of 550
mm behind the source 24. 18711099 1(GHMatters) P10 139.AU.1
Also shown in Figures 2 (a) and (b) are the inner tube 30
and the outer tube 32 of the reverse circulation drill rod
positioned in the bulk formation 34. As indicated in
Figure 2(b), the short space detector 26 has a depth of
investigation of approximately 175 mm and the long space
detector 28 has a depth of investigation of approximately
275 mm.
In this embodiment the source 24 is arranged to generate
non-collimated gamma radiation, which has the advantage
that a measurement result is largely independent from a
rotation of the measurement tool 20 within the inner tube
30 when the measurement tool 20 is lowered or lifted
within the inner tube 30 during a measurement.
Further, the method 10 comprises step 19 of determining
the property, such as the density, of the bulk formation
using the detected radiation response.
Referring now to Figure 3, a measurement detector 300 is
positioned in the inner tube 302 of a reverse circulation
drill rod of a reverse circulation drilling system. The
inner tube 302 is surrounded by an outer tube 304. The
inner tube 302 has in this embodiment an inner diameter of
48 mm and the outer tube 304 has in this embodiment an
outer diameter of 4.5 inches. The measurement tool 300 has
an outer diameter of approximately 42 mm, and consequently
can freely be lowered or lifted within the inner tube 302.
A person skilled in the art will appreciate that
alternatively the inner tube 302, the outer tube 304 and
measurement tool 300 may have other suitable diameters.
The outer tube 304 is positioned in a borehole in the bulk
formation 305.
Figure 3 shows a space between a wall of the borehole and
the outer tube 304 partially filled with water 306.
Further, the inner tube 302 is partially filled with
water. The water levels within the inner tube 302 and
within the outer tube 304 are substantially identical.
The method 10 comprises step 20 of determining the
property of the bulk formation. As will be described below
in further detail, determining the property of the bulk
formation comprises modelling.
Referring now to Figure 4, it is described in further
detail how the property is determined. In this embodiment
the property is the density of the bulk formation.
Figure 4 shows plot 400, which represents the density of a
formation that surrounds a borehole as a function of depth
and was determined using a method in accordance with an
embodiment of the present invention. Reverse circulation
drill rods we are present during the measurement. The data
was obtained using a measurement tool that comprises an
uncollimated Cobalt 60 source and is schematically shown
in Figure 3 and described above.
Plot 402 represents the density of the formation as
determined using a conventional open hole measurement tool
for the formation around the same borehole and depth
range, but with the reverse circulation drill rods being
removed.
18711099 1(GHMatters) P10 139.AU.1
The measurement tool had a collimated Cobalt 60 source, a
short space detector positioned at 190 mm behind the
source and a long space detector positioned at 380 mm
behind the source.
Figure 4 shows plots 400 and 402 for a short distance of a
few metres along the borehole.
Plot 404 shows caliper data as a function of depth and
provides information concerning the diameter of the
borehole. The data were obtained using a caliper tool that
has arms that push against the borehole wall and provide a
varying an electrical signal as a function of width of the
borehole.
Plot 406 shows resistivity data for the formation
surrounding the borehole. The resistivity data was
obtained using an open hole arrangement of electrical
probes in a measurement tool and characterise electrical
properties of the formation surrounding the borehole, and
consequently characterise material properties of the
formation surrounding the borehole. A person skilled in
the art will appreciate that various methods are known to
determine the resistivity as a function of depth of the
formation surrounding the bore hole.
The plot 402 was calculated using measurement data
obtained from the open hole measurement tool using methods
that are well-known in the art. Reference is made in
particular to prior art publication entitled "The Dual
Spaced Density Log-Characteristics, Calibration and
Compensation"; Samworth, The Log Analyst, February 1992.
The plot 400 was calculated using the same general
principles as used for the calculation of plot 402 but, as
mentioned above, using measurement data obtained with the
measurement tool 300 that was lowered within the reverse
circulation drill rods of a reverse circulation drill
system.
Plot 408 shows calculated compensation data used for
calculating the plot 400. Generally, compensation is used
to determine the density of the formation using a
measurement tool that has short and long space detectors
to correct for influences of factors that are unrelated to
the density of the formation surrounding the borehole
(again reference is being made in particular to the above
identified prior art publication). The measurement data
taken with the long space detector 28 has a larger depth
of investigation than the data taken with the short space
detector 26. Consequently, the data taken with the short
space detector 26 is more influenced by an influence of
the mudcake etc, and for embodiments of the present
invention an influence of the inner and outer tube of the
reverse circulation drill rods. It is consequently
possible to calculate a compensation that can be used to
correct the output of the long space detector 28 for such
influences. Plot 408 shows the calculated compensation,
which is dependent on the output of the short space
detector 26 and a variable that dependents on properties
of the measurement tool 20 (such as the difference in
spacing between the short space detector 26 and long space
detector 28 relative to the source 24).
18711099 1(GHMatters) P10 139.AU.1
By comparing plots 400 and 402 it will become apparent
that there is an overall match of main features of the
plots in depth regions in which the borehole has a largely
uniform diameter. Where plots 400 and 402 overlap there is
a relatively good correlation. Where the correlation
between plots 400 and 402 is poor (for example in a depth
region between 67 and 68 m) are regions in which the
borehole has widened significantly (as indicated by
Caliper data plot 404).
The measurement data shown in plot 402 obtained using a
method in accordance with the present invention may also
be calibrated using a signal from a measurement tool that
is lowered along a reverse circulation drill rod
positioned in a formation having a known and uniform
density.
Modifications and variations as would be apparent to a
skilled addressee are deemed to be within the scope of the
present invention. For example, a person skilled in the
art will appreciate the source may not necessarily be a
Cobalt 60 source, but may alternatively also be another
type of source, such as a Caesium 137 source.
The reference that is been made to the prior art
publication by Samworth does not constitute an admission
that prior art publication is part of the common general
knowledge in Australia or any other country.
Claims (5)
1. A method of determining a density of a bulk formation
that at least partially surrounds a borehole, the method
comprising the steps of:
providing the borehole in the bulk formation with at
least one drill rod being positioned within the borehole
as a result of providing the borehole, the at least one
drill rod comprising a first tube and a second tube that
surrounds the first tube;
retaining the drill rod in place in the borehole;
inserting a measurement tool into the first tube of
the at least one drill rod and moving the measurement tool
within the first tube along the borehole;
emitting radiation from the measurement tool through
the first and second tubes into the bulk formation;
detecting a radiation through the first and second
tubes; and
determining the density of the bulk formation using
the detected radiation response.
2. The method of claim 1 wherein the drill rod is a
reverse circulation drill rod of a reverse circulation
drill system.
3. The method of claim 1 or claim 2, wherein
the determining includes compensating for the presence of
the first and second tubes when determining the density of
the bulk formation.
4. The method of any one of the preceding claims wherein
the measurement tool has an outer diameter of 40 - 50mm. 18711099 1(GHMatters) P10 139.AU.1
5. The method of any one of the preceding claims wherein the bulk formation comprises iron ore.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2016100133A AU2016100133B4 (en) | 2016-02-08 | 2016-02-08 | A method of determining a property of a bulk formation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2016100133A AU2016100133B4 (en) | 2016-02-08 | 2016-02-08 | A method of determining a property of a bulk formation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2016100133A4 AU2016100133A4 (en) | 2016-03-10 |
| AU2016100133B4 true AU2016100133B4 (en) | 2022-06-02 |
Family
ID=55484082
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2016100133A Expired AU2016100133B4 (en) | 2016-02-08 | 2016-02-08 | A method of determining a property of a bulk formation |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU2016100133B4 (en) |
-
2016
- 2016-02-08 AU AU2016100133A patent/AU2016100133B4/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU2016100133A4 (en) | 2016-03-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGI | Letters patent sealed or granted (innovation patent) | ||
| HB | Alteration of name in register |
Owner name: KINETIC LOGGING SERVICES PTY LTD Free format text: FORMER NAME(S): SURTRON TECHNOLOGIES (AUSTRALIA) PTY LTD |
|
| FF | Certified innovation patent | ||
| MK22 | Patent ceased section 143a(d), or expired - non payment of renewal fee or expiry |