Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION:
Air Operated Earth Drilling Tool
FIELD OF THE INVENTION
The present invention relates to an air operated earth
drilling tool.
BACKGROUND OF THE INVENTION
It has been determined that liquid drilling fluids
circulated when drilling oil and gas wells have an undesirable
side effect of sealing off portions of the formation. This has
resulted in an increase in the use of gaseous drilling fluids,
commonly referred to as "air drilling".
United States Patents 4,880,065 (McDonald et al 1989) and
4,936,397 (McDonald et al 1990) disclose air operated earth
drilling tools. The McDonald 1989 reference discloses an air
operated earth drilling tool that has a rotor with vanes. As
air passes through the tool, the air contacts the vanes and
imparts a rotary movement to the rotor. A gear reduction unit
is provided to slow the drilling bit attachment end of the
tool, to a desired rotations per minute. A conical screen is
provided to capture contaminants which are carried in the air
flow that might otherwise damage the tool. The McDonald 1990
reference discloses an air operated drilling tool that has a
rotor and stator. A control valve is placed upstream of the
tool in order to allow pressure to build up to deliver impulse
energy to blow out accumulated well fluids and initiate
operation of the tool after each joint of drill pipe is added
to the drill string.
SU1~IARY OF THE INVENTION
The present invention relates to an alternative form of
air operated earth drilling tool.
According to the present invention there is provided an
air operated earth drilling tool which includes a tubular
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housing having a first end, a second end, and at least one air
flow passage. A filter adapted to remove solid contaminants
is positioned at the first end of the housing. A metering
valve is positioned on the at least one air flow passage,
whereby the volume of air passing through the downhole motor
assembly is metered to provide a selected rotational speed.
An inner mandrel with a central air flow passage is
telescopically received in the second end of the housing and
is rotatable relative to the housing. Means is provided for
diverting air flow from the at least one air flow passage of
the housing to the central air flow passage of the mandrel.
At least one rotatable power section is disposed within the
housing. The at least one power section has a plurality of
outwardly extending vanes, such that air passing by the vanes
rotates the at least one power section. Means is provided for
connecting the power section to the mandrel, such that rotation
of the power section rotates the mandrel.
with the air operated earth drilling tool, as described
above, a speed is controlled by metering of the air flow rather
than by the use of planetary speed reduction assemblies as
taught by the McDonald et al 1989 reference.
Although beneficial results may be obtained through the
use of the apparatus, as described above, McDonald et al 1990
required a control valve above the tool to allow pressure to
build in order to blow out well fluids that enter the tool
while adding additional sections of drill pipe to the pipe
string. Even more beneficial results may, therefore, be
obtained when a one way check valve is positioned in the
central passage of the mandrel. This valve prevents fluids in
the wellbore from entering the housing when the supply of air
is turned off.
Although beneficial results may be obtained through the
use of the air operated earth drilling tool, as described
above, the McDonald et al 1989 reference included a conical
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filter for solid contaminants. The disadvantage of such a
filter is that air flow is adversely affected as solid
contaminants build up in the filter. Even more beneficial
results may, therefore, be obtained when the filter includes
a body having a first end, a second end, and an intermediate
portion between the first end and the second end. At least one
inlet passage extends inwardly from the first end and
terminates past the intermediate portion in a blind bore which
functions as a contaminant receiving receptacle. At least one
outlet passage extends from the second end past the
intermediate portion. At least one diversion passage extends
at an angle from the intermediate portion back toward the first
end of the body to intersect the at least one outlet passage.
Solid contaminants passing through the at least one inlet
passage accumulate in the contaminant receiving receptacle
while air escapes through the at least one diversion passage
to the at least one outlet passage. This configuration removes
the solid contaminants from the path the air travels.
Although beneficial results may be obtained through the
use of the air operated earth drilling tool, as described
above, the trap type solids contaminant filter functions better
when at least one deflector is positioned in the intermediate
portion in the path of the at least one inlet passage. The
deflector has a plurality of apertures and is positioned
upstream of the contaminant receiving receptacle. Solid
contaminants which strike the at least one deflector pass
through the plurality of apertures and accumulate in the
contaminant receiving receptacle, while air is deflected.
Beneficial results have been obtained through the use of a
single conical deflector.
Although the metering valve can take a number of forms,
beneficial results have been obtained when the valve is
incorporated into the filter between the at least one diversion
passage and the at least one outlet passage. The valve
determines what percentage of the at least one diversion
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passage remains in fluid communication with the at least one
outlet passage. The valve is more effective when there are a
plurality of diversions passages communicate with a plurality
of outlet passages. The preferred form of valve includes a
valve plate. The positioning of the valve plate determines
what percentage of air flow passes through t:he at least one air
passage. Beneficial results have been obtained through the
use of a valve plate which is rotatable. There are various
means by which the valve plate may be maintained in a selected
rotational position, such as through the use of fasteners.
Although beneficial results may be obtained through the
use of the air operated earth drilling tool, as described
above, the torque requirements of various drilling applications
may vary. Even more beneficial results may, therefore, be
obtained when a plurality of modular power sections are
provided. This enables torque to be adjusted by either adding
or eliminating power sections.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, the drawings are for the purpose
of illustration only and are not intended to in any way limit
the scope of the invention to the particular embodiment or
embodiments shown, wherein:
FIGURE 1 is a side elevation view, in section, of an air
operated earth drilling tool constructed in accordance with the
teachings of the present invention.
FIGURE 2 is a side elevation view, in section, of a filter
containing a valve from the air operated earth drilling tool
illustrated in FIGURE 1.
FIGURE 3 is a detailed side elevation view, in section,
of a valve plate from filter containing a valve illustrated in
FIGURE 2 from the air operated earth drilling tool filter
illustrated in FIGURE 1.
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FIGURE 4 is a top plan view, in section, of the filter
containing a valve illustrated in FIGURE 2 from the air
operated earth drilling tool illustrated in FIGURE 1, with the
valve plate oriented to place the diversion passages in a full
5 open position relative to the outlet passages.
FIGURE 5 is a top plan view, in section, of the filter
containing the valve illustrated in FIGURE 2 from the air
operated earth drilling tool illustrated in FIGURE 1, with the
valve plate oriented to place the diversion passages in a 75%
open position relative to the outlet passages.
FIGURE 6 is a top plan view, in section, of the filter
containing a valve illustrated in FIGURE 2 from the air
operated earth drilling tool illustrated in FIGURE 1, with the
valve plate oriented to place the diversion passages in a 50%
open position relative to the outlet passages.
FIGURE 7 is a top plan view, in section, of the filter
containing a valve illustrated in FIGURE 2 from the air
operated earth drilling tool illustrated in FIGURE 1, with the
valve plate oriented to place the diversion passages in a 25%
open position relative to the outlet passages.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, an air operated earth drilling
tool generally identified by reference numeral 100, will now
be described with reference to FIGURES 1 through 7.
Structure and Relationship of Parts:
There will first be described a solids contaminant filter,
generally identified by reference numeral 10. Referring to
FIGURE 2, solid contaminants filter 10 has a body 12 with a
first end 14, a second end 16, and an intermediate portion 18
between first end 14 and second end 16. An inlet passage 20
extends inwardly from first end 14 and terminates past
intermediate portion 18 in a blind bore 22 which functions as
a contaminant receiving receptacle 24. A deflector 26 is
positioned in intermediate portion 18 in the path 28 of inlet
passage 20. In the illustrated embodiment, deflector 26 is
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conical, however it will be appreciated that deflector 26 can
be of a variety of alternate shapes and configurations.
Deflector 26 has a plurality of apertures 30 and is positioned
upstream of contaminant receiving receptacle 24, such that
solid contaminants which strike deflector 26 pass through
plurality of apertures 30 and accumulate in contaminant
receiving receptacle 24. A plurality of outlet passages 32
extend from second end 16 past intermediate portion 18. A
plurality of diversion passages 34 extend at an angle from
intermediate portion 18 back toward first end 14 of body 12.
Each diversion passage 34 intersects with one of outlet
passages 32, such that air deflected by deflector 26 escapes
through diversion passages 34 to outlet passages 32.
Incorporated in to solids contaminant filter is a metering
valve which includes a valve plate 36 disposed between
diversion passages 34 and outlet passages 32. Referring to
FIGURE 3, valve plate 36 has apertures 38 for air flow.
Referring to FIGURES 4, 5, 6 and 7, as will hereinafter be
further described the positioning of apertures 38 of valve
plate 36 determines what percentage of diversion passages 34
remain in fluid communication with outlet passages 32. Valve
plate 36 is rotatable to vary the positioning of apertures 38
and then can be maintained in the selected rotational position
by inserting a fastener pin 40 into a receiving slot 42 on
valve plate 36.
Incorporation into a downhole motor assembly:
Referring to FIGURE 1, body 12 of solid contaminants
filter 10 forms part of air operated earth drilling tool 100.
which includes a tubular housing 46 with a first end 48, a
second end 50, and a peripheral air flow passage 52. Body 12
of solid contaminants filter 10 is positioned at first end 48
of housing 46. Referring to FIGURES 1 and 7, second end 16 of
body 12 has exterior threads 54 adapted for threaded engagement
with interior threads 56 at first end 48 of housing 46.
Referring to FIGURE 1, first end 14 of body 12 has interior
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threads 58 adapted to be threadably engaged with drill pipe.
Referring to FIGURE 7, an inner mandrel 60 with a central
air flow passage 62 is telescopically received in second end
50 of housing 46. Inner mandrel 60 is rotatable relative to
housing 46. Air flow channels 64 are provided for diverting
air flow from peripheral air flow passage 52 of housing 46 to
central air flow passage 62 of mandrel 60.
A plurality of modular power sections 66 are disposed
within housing 46. Although the illustrated embodiment has two
rotatable power sections 66, it will be appreciated that there
could be only one, or alternatively more than two. Each power
section 66 has a plurality of outwardly extending vanes 68,
such that air passing by vanes 68 rotates power sections 66.
Power sections 66 are secured together by a connecting sleeve
70. Bearings 72 are provided on each power section 66 to
facilitate rotation of vanes 68.
A threaded engagement 74 is provided for connecting power
section 66 to mandrel 60, such that rotation of power sections
66 rotate mandrel 60. Bearings 76 are provided to facilitate
rotation of mandrel 60. A one way check valve 78 is positioned
in central passage 62 of mandrel 60 to prevent fluids in the
wellbore from entering housing 46 when the supply of air is
turned off. A seal 80 is also provided on mandrel 60 to
prevent fluid from entering bearings 76.
Operation:
The use and operation of solid contaminants filter 10 will
now be described with reference to FIGURES 1 through 7.
Referring to FIGURE 2, solid contaminants filter 10, as
described above serves two functions when used for air
drilling. One function of solids contaminants filter 10 is to
capture solid contaminants in contaminant receiving receptacle
24 while letting air pass through. Solid contaminants are the
rust and scale that tend to accumulate on the interior of a
drilling pipe. As turbulence occurs, some solid contaminants
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break away. If allowed to pass along with air, solid
contaminants cause damage to vanes 68 such that power sections
66 do not function as intended thereby interfering with the
operation of air operating drilling tool 100. With solid
contaminants filter 10 as described above, air is deflected by
deflector 26 into diversion passages 34 while solid
contaminants are collected in contaminant receiving receptacle
24. After passing through solid contaminants filter 10, air
passes through vanes 68 in order to power air operated drilling
tool 100.
Solid contaminants filter 10 also has incorporated in its
construction a metering valve which serves a metering function
whereby control is maintained over the volume of air passing
through solid contaminants filter 10 and entering power section
66 to power air operated drilling tool 100. Referring to
FIGURES 4, 5, 6 and 7, the volume of air passing through air
operated drilling tool 100 to provide a selected rotational
speed is metered by the positioning of valve plate 36 in solid
contaminants filter 10. Valve plate 36 is rotated into a
selected position to select the rotation speed required to
operate air operated drilling tool 100. Referring to FIGURE 4,
when valve plate 36 is oriented so as to place apertures 38 in
full open alignment relative to diversion passages 34 and
outlet passages 32, then maximum air flow is achieved.
Referring to FIGURE 5, when valve plate 36 is oriented to place
apertures 38 in a 75% open position relative to diversion
passages 34 and outlet passages 32, then air flow is at 75% of
its maximum. Referring to FIGURE 6, when valve plate 36 is
oriented to place apertures 38 in a 50% open position relative
to diversion passages 34 and outlet passages 32, then air flow
is reduced to 50% of its maximum. Referring to FIGURE 7, when
valve plate 36 is oriented to place apertures 38 in a 25% open
position relative to diversion passages 34 and outlet passages
32, then air flow is reduced to 25% of its maximum. By
metering the air flow, rotational speed can be controlled to
be optimum for the intended drilling application. When valve
plate 36 has been rotated to the selected position, valve plate
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36 is maintained in position by inserting fastener pin 40 into
receiving slot 42 on valve plate 36. The maximum torque air
operating drilling tool is capable of providing depends upon
the number of power sections 66 is has. If there is not enough
torque provided when valve plate 36 is in a full open position,
additional power sections 66 must be added. It can be seen how
air operated drilling tool can be adapted for any application
by either adding or eliminating power sections and metering air
flow via valve plate 36. By means of these two adjustments a
desired rotational speed and output torque can be achieved.
In this patent document, the word "comprising" is used in
its non-limiting sense to mean that items following the word
are included, but items not specifically mentioned are not
excluded. A reference to an element by the indefinite article
"a" does not exclude the possibility that more than one of the
element is present, unless the context clearly requires that
there be one and only one of the elements.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
