Note: Descriptions are shown in the official language in which they were submitted.
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Ultra High Pressure Hydraulic Sublevel Pipe Cutter
Field of the Invention
The present invention relates to ultra-high pressure (UHP) cutters, and
specifically to UHP
cutters for sublevel use for cutting pipe casings and liners for example in
the dismantling of
existing oil, gas and/or utility well bores or lines.
Background
The abandonment of non-producing or uneconomic oil or gas wells presents a
number of safety
and environment issues. Typically, in the abandonment process, all production
and surface
wellbore casings along with conductor barrels and cement liners have to be
removed to a depth
of two metres below the surface.
A previous method for such removal required a large scale excavation of soil
from around the
existing wellbore. In order to do this, line location companies needed to be
brought in to
determine locations of any existing oil, gas and/or utility lines. Proper
safety practices typically
require that a very large area be excavated to allow a welder and an assistant
to descend into the
area to the required depth to cut the existing steel casings and cement
liners. This cutting of the
casing is done using a cutting torch.
Typically, the casing is cut horizontally and then vertically to remove the
outer layer. Any
cement present then has to be removed using either a jackhammer or sledge
hammer. This
allows access to secondary steel casings that are cut using the cutting torch
again.
Throughout this process, a source of ignition, the cutting torch, is being
used in an area wherein
there is a possibility for the presence of explosive or flammable gases or
liquids. This type of
work environment may be referred to as a hot work area. A significant safety
threat is inherent
for the personnel in a hot work area and is further exasperated through the
used of a cutting torch
or any other heat based cutting tool.
One previous attempt at overcoming this issue was to provide a different type
of tool consisting
of metal blades that would be lowered inside the casing and then rotated and
expanded to cut
through the casing. Such a tool is described in U.S. Patent 5,685,078. Some
problems associate
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with this tool and this method of cutting are that if there is an movement of
the casing while
being cut, the tool becomes jammed inside the casing. In addition, being a
metal on metal cut,
there is still the possibility of sparking which can ignite any explosive or
flammable gas or fluid
and can also cause a heat build-up which may ignite any explosive or flammable
gas or fluid in
the hot work area. Further, the tool can only cut only layer at a time and has
to be removed and
set to a different cutting depth for each cut. Finally, this type of tool does
not cut well or
sometime at all, though cement.
There is therefore a need to provide a cutting tool that overcomes one or more
of the
shortcomings of the current cutting tools or methods outlined above and/or
observed in the field.
Summary of the Invention
An ultra-high pressure (UHP) cutting device is provided that foregoes the need
for heat or spark
generating friction to cut through the components of a wellbore, including the
liner and the
casing, from the inside to the outside. Ultra-high pressure fluid, optionally
in combination with
an abrasive, is used to cut through the wellbore and as a result the risk of
igniting explosive or
flammable gas or fluid is greatly reduced or removed. By using a tool,
insertable into the
wellbore casing, that cuts from the inside of the bore to the outside, the
need for excavation
around the well is reduced or avoided. In addition, the UHP cutting device may
cut through
multiple layers of steel and/or cement in a single pass thereby avoiding the
need to reset the
cutting tool to different depths for each pass or each cut.
In one embodiment, the UHP cutting device may be designed to be of a
sufficient weight to be a
portable unit that is sufficiently quick and easy to assembly so that it may
be used in extreme
cold weather conditions, where, typically, water usage would not be practical.
One embodiment of the invention provides for an ultra-high pressure (UHP)
cutting device for
insertion into a wellbore for cutting the casing of the wellbore from within
the wellbore, the UHP
cutting device comprising:
a UHP hose connector for connection with a UHP hose in communication with a
fluid
source;
a rotatable UHP tube with a top end in fluid communication with the UHP hose
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1 L
connector and a bottom end opposite the top end;
a rotating means in operational communication with the UHP tube for rotating
the UHP
tube during operation of the cutting device; and
a cutter head in fluid communication with the bottom end of the UHP tube, the
cutter
head comprising:
a UHP elbow for changing the direction of UHP fluid flow from a direction
substantially parallel with the wellbore to a direction toward the inner
surface of the
wellbore;
an abrasive feed port for connection with an abrasive feed line for receiving
abrasive to be mixed with the UHP fluid; and
a focus tube for directing the mixture of UHP fluid and abrasive out of the
cutter
head and toward the inner surface of the wellbore to be cut.
In addition to the embodiment(s) outlined above, the cutting device may
further comprise a
centralizer device for centering the UHP tube in the wellbore during operation
of the cutting
device.
In addition to the embodiment(s) outlined above, the cutting device may
further comprise a
hollow housing situated around a majority of the length of the UHP tube, the
housing fixed to a
non-rotating component of the cutting device such that the housing remains
stationary during
rotation of the UHP tube.
In addition to the embodiment(s) outlined above, the centralizer device
comprises:
a centralizer adjustment block slidable along the housing and lockable to the
housing to
prevent sliding of the centralizer adjustment block when locked;
an expandable centralizer rod system comprising a series of rods and hinges;
centralizer adjustment rods connected at an upper end to the centralizer
adjustment block
and at a lower end to the centralizer rod system such that downward sliding of
the centralizer
adjustment block operates the hinges of the centralizer rod system and expands
the outside
diameter of the centralizer rod system and upward sliding of the centralizer
adjustment block
operates the hinges of the centralizer rod system to collapse the outside
diameter of the
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centralizer rod system;
a locking device in communication with the centralizer adjustment rods,
wherein
operation of the device provides for a small expansion of the centralizer rod
system via the
centralizer adjustment rods for locking the centralizer rod system against an
inner surface of the
wellbore; and
a centralizer mounting bracket fixed to the housing for connection of the
centralizer
device to the cutting device;
wherein expansion of the centralizer rod system until the rods of the
centralizer rod
system contact the inner surface of the wellbore centers the UHP tube in the
wellbore.
In addition to the embodiment(s) outlined above, the locking device is a
locking handle or a
locking bolt.
In addition to the embodiment(s) outlined above, the cutting head further
comprises an orifice
assembly for reducing the fluid flow rate and increasing the fluid pressure.
In addition to the embodiment(s) outlined above, the cutting device further
comprises a UHP
manifold in fluid communication with the UHP tube and the cutter head, the UHP
manifold
comprising a plurality of fluid transmission holes, each hole suitable for
connection with the
cutter head to orient the cutter head at a different offset from the UHP tube
thereby providing a
different offset for the focus tube.
In addition to the embodiment(s) outlined above, the cutting device further
comprises a gear
reduction unit in communication with the rotating means and the UHP tube for
reducing the rate
of rotation of the UHP tube provided by the rotation means.
In addition to the embodiment(s) outlined above, the rotating means is a
hydraulic motor.
In addition to the embodiment(s) outlined above, the cutting device further
comprises a UHP
swivel attachment connected to the UHP hose connector and the UHP tube, the
UHP swivel
attachment providing a sealed rotatable connection between the UHP tube and
the UHP hose
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connector allowing the UHP tube to rotate while the UHP hose connector remains
stationary.
In another embodiment, the present invention provides for an ultra-high
pressure (UHP) cutting
device for insertion into a wellbore for cutting the casing of the wellbore
from within the
wellbore, the UHP cutting device comprising:
a UHP hose connector for connection with a UHP hose in communication with a
fluid
source;
a rotatable UHP tube with a top end in fluid communication with the UHP hose
connector and a bottom end opposite the top end;
a UHP swivel attachment connected to the UHP hose connector and the UHP tube,
the
UHP swivel attachment providing a sealed rotatable connection between the UHP
tube and the
UHP hose connector allowing the UHP tube to rotate while the UHP hose
connector remains
stationary;
a hollow housing situated around a majority of the length of the UHP tube, the
housing
fixed to a non-rotating component of the cutting device such that the housing
remains stationary
during rotation of the UHP tube;
a rotating means in operational communication with the UHP tube for rotating
the UHP
tube during operation of the cutting device;
a gear reduction unit in communication with the rotating means and the UHP
tube for
reducing the rate of rotation of the UHP tube provided by the rotation means;
a cutter head in fluid communication with the bottom end of the UHP tube, the
cutter
head comprising:
a UHP elbow for changing the direction of UHP fluid flow from a direction
substantially parallel with the wellbore to a direction toward the inner
surface of the
wellbore;
an abrasive feed port for connection with an abrasive feed line for receiving
abrasive to be mixed with the UHP fluid;
a focus tube for directing the mixture of UHP fluid and abrasive out of the
cutter head
and toward the inner surface of the wellbore to be cut; and
a centralizer device for centering the UHP tube in the wellbore during
operation of the
cutting device, the centralizer device comprising:
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a centralizer adjustment block slidable along the housing and lockable to the
housing to prevent sliding of the centralizer adjustment block when locked;
an expandable centralizer rod system comprising a series of rods and hinges;
centralizer adjustment rods connected at an upper end to the centralizer
adjustment block and at a lower end to the centralizer rod system such that
downward
sliding of the centralizer adjustment block operates the hinges of the
centralizer rod
system and expands the outside diameter of the centralizer rod system and
upward sliding
of the centralizer adjustment block operates the hinges of the centralizer rod
system to
collapse the outside diameter of the centralizer rod system;
a locking device in communication with the centralizer adjustment rods,
wherein
operation of the device provides for a small expansion of the centralizer rod
system via
the centralizer adjustment rods for locking the centralizer rod system against
an inner
surface of the wellbore; and
a centralizer mounting bracket fixed to the housing for connection of the
centralizer device to the cutting device;
wherein expansion of the centralizer rod system until the rods of the
centralizer
rod system contact the inner surface of the wellbore centers the UHP tube in
the wellbore.
In addition to the embodiment(s) outlined above, the rotating means is a
hydraulic motor.
In addition to the embodiment(s) outlined above, the cutting head further
comprises an orifice
assembly for reducing the fluid flow rate and increasing the fluid pressure.
In addition to the embodiment(s) outlined above, the cutting device further
comprises a UHP
manifold in fluid communication with the UHP tube and the cutter head, the UHP
manifold
comprising a plurality of fluid transmission holes, each hole suitable for
connection with the
cutter head to orient the cutter head at a different offset from the UHP tube
thereby providing a
different offset for the focus tube.
In addition to the embodiment(s) outlined above, the UHP tube is a stainless
steel UHP tube.
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Brief Description of the Drawings
Figure 1 is a schematic view illustrative of one embodiment of a UHP cutting
device for
insertion into a wellbore or the like, for cutting through the components of
the wellbore including
the liner and the casing; and
Figure 2 is a photograph illustrative of one embodiment of a UHP swivel
attachment and a
hydraulic setup for a UHP cutting device;
Figure 3 is a photograph illustrative of one embodiment of a centralizer
system for a UHP cutting
device;
Figure 4 is a photograph illustrative of one embodiment of a centralizer
adjustment assembly for
a UHP cutting device;
Figure 5 is a photograph illustrative of one embodiment of a depth adjustment
block with
optional size extensions for a UHP cutting device;
Figure 6 is a photograph illustrative of one embodiment of a cutter head and a
manifold assembly
for a UHP cutting device;
Figure 7 is a chart showing data relating to suitable focus tube lengths
relating to the diameter of
the wellbore for one embodiment of a focus tube; and
Figure 8 is a front elevation view of one example of a UHP manifold for use
with an
embodiment of a cutting device.
Detailed Description
Generally, once an oil or gas well is non-producing or uneconomical to
continue operation, the
surface abandonment of the well is carried out. The surface abandonment
typically involves the
removal of all production and surface wellbore casings along with cement
liners to a depth of
two metres below the surface. An ultra-high pressure (UHP) cutting device for
insertion into a
wellbore for cutting through the casing and, if present, the liner of the well
so that the wellbore
casing and liner may be removed to a depth of two meters below the surface
without the need for
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excavation of the site is provided and shown schematically, in one embodiment
thereof, with
reference to Figure 1.
One embodiment of the UHP cutting device is shown generally at 30. The cutting
device 30 is
inserted into the wellbore to be cut (not shown) and a combination of fluid,
typically water, and
an abrasive are exhausted through a focus tube 23 substantially perpendicular
to the casing or
liner into the casing or liner at an ultra-high pressure sufficient to cut
through the casing and
liner. The cutting device 30 is rotated during operation so that a continuous
cut through the liner
and casing is made upon completion of a full rotation of the cutter head 21.
It will be
appreciated that the pressure and rate of rotation may be determined based on
the materials and
thickness of the casing and liner as well as the strength of the components of
the cutting device
30.
The cutting device 30 shown in Figure 1 comprises a UHP hose connection 1 at a
top of the
cutting device so that a UHP hose may be connected for delivering fluid, such
as water, from an
UHP pump. Generally, the UHP hose is connected after insertion of the cutting
device 30 into a
wellbore, however, connection may be done before insertion of the cutting
device into the
wellbore. By positioning the UHP hose connection 1 at or near the top of the
cutting device 30,
connection of the UHP hose after insertion of the cutting device 30 is
facilitated. This also helps
to reduced tangling of the UHP hose and ease of rotation of the cutting device
30 during
operation.
A swivel attachment 2 provides a fluid connection from the UHP hose connection
1 with a UHP
tube 4, typically a stainless steel tube, and allows the UHP hose to remain
substantially
stationary or non-rotational when the UHP tube 4 is rotating during operation
of the cutting
device 30. A collar 3 may be used to fluidly connect the swivel attachment 2
with the UHP tube
4. It will be appreciated that all connections must be sufficiently robust to
withstand ultra-high
pressures without leaking or breaking.
The UHP tube 4 extends to the bottom of the cutting device 30 and allows for
fluid
communication of the fluid with a UHP manifold 17 which directs the UHP fluid
through a UHP
elbow 19, generally 90 degrees, with an orifice assembly 20. The orifice
assembly 20 reduces
the fluid flow rate and increases the pressure of the fluid as it travels to
the cutter head 21 and is
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directed out of the focus tube 23. The cutter head 21 includes an abrasive
feed port 22 to which
an abrasive feed line 25 is attached for supplying abrasive to the cutter head
from an external
abrasive source for combining with the fluid for eventual direction out
through the focus tube 23.
During normal operation, the abrasive that is fed to the cutter head 21
through the abrasive feed
port 22 is drawn though the abrasive feed line 25 by suction, or a reduction
in pressure, created
by the high pressure fluid, namely water, passing over the abrasive feed port
22 in the cutter head
21.
The UHP manifold 17 may contain a number of apertures suitable for fluid
transmission from the
UHP tube 4 to the cutter head 21. The positioning of each aperture allows for
various offset
changes in the cutter head 21 and by extension the focus tube 23 by directing
the flow of the
UHP fluid through a particular aperture. In addition, the diameter of any of
the apertures in the
manifold 17 may be different than the inside diameter of the UHP tube 4
thereby effecting the
fluid pressure in the cutter head 21. The cutter head 21 may be connected
directly or indirectly
to any of the apertures in the UHP manifold 17 to allow for a suitable
distance between the focus
tube 23 and the inner surface of the liner or casing. One example of a UHP
manifold 17 is
shown in Figure 8 which contains apertures A, B and C. On the UHP manifold 17,
aperture A is
the farthest aperture from the center of the UHP manifold 17, aperture B is
the center aperture
and aperture C is closer to B then A to allow for a variety of potential
setups and distances.
Optionally, an extension head in communication with any of the apertures on
one end and the
cutter head 21 may be used to reposition the cutter 21 at a desired position a
suitable distance
from the inner surface of the wellbore.
A tube nipple with gland nut 18 may be used to attach the UHP elbow 19 to the
UHP manifold
17. A collet and nut 24 may be used to retain the focus tube 23 inside the
cutter head 21.
One embodiment of a cutter head 21 with a focus tube 23, abrasive feed port
22, tube nipple with
gland nut 18, UHP elbow 19, collet and nut 24 and UHP manifold 17 is shown in
detail in the
photograph of Figure 6.
A rotating means is used to rotate the UHP tube 4 and thereby rotate the
cutter head 21 and the
focus tube 23 to rotate the direction of the fluid/abrasive around the
circumference of the
wellbore so that the liner and casing are cut. As will be appreciated, the
rotating means may be
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external the cutting device 30. However, to allow for ease of use and
portability, the rotating
means may be attached to the cutting device 30 and should also be of a
sufficiently small size
and shape so that it fits into the wellbore when the cutting device is
inserted. In the embodiment
illustrated in Figure 1, a hydraulic motor 5 is used in connection with a gear
reduction unit 6 in
communication with the UHP tube 4. The hydraulic motor 5 rotates the UHP tube
4 via the gear
reduction unit 6 which has includes gearing to reduce the rate of rotation of
the UHP tube 4. It
will be appreciated that any suitable hydraulic more 5 and gear reduction unit
6 may be used that
provides for rotation of the UHP tube 4 at a rate suitable to cut the liner
and casing of the
wellbore at the desired fluid pressure. It will also be appreciated that any
method or means of
operatively connecting the hydraulic motor 5, the gear reduction unit 6 and
the UHP tube 4 may
be employed. In the embodiment shown in Figure 1, a gland nut 7 is used to
secure the UHP
tube 4 with the gear reduction unit 6 to allow for rotation of the UHP tube 4.
Hydraulic fluid
lines in communication with a reservoir or other fluid source are used to
input and output
hydraulic fluid to the hydraulic motor 5.
A housing 9 is used to house the UHP tube 4 which passes through the housing
9. The housing 9
basically acts as a shield and allows the UHP tube 4 to rotate inside the
housing 9 while the
housing 9 remains stationary. The housing 9 also acts as a mounting point for
the hydraulic
motor 5 and gear reduction unit 6 in addition to other components that do not
rotate during
operation of the cutter head 21. A mounting bracket 8 is shown as connecting
the gear reduction
unit 6 to the housing 9 that surrounds the UHP tube 4. It will be appreciated
that any means may
be used to connect the gear reduction unit 6 and/or the hydraulic motor 5 with
the housing 9. A
bushing 16 may be used to locate or centre the UHP tube 4 in the housing 9 and
allow rotation of
the UHP tube 4 in the housing while ensuring the UHP tube 4 does not touch the
sides of the
housing 9. The bushing 16 may be a brass bushing.
One example of the top end setup of a UHP cutting device 30 with the hydraulic
lines attached
before insertion into a wellbore is shown in Figure 2.
As outlined above, typically, the abandonment process of a non-producing or
uneconomic oil or
gas well calls for the removal of wellbore casings along with liners to a
predetermined depth,
generally of two metres below the surface. As wellbore casings extend above
the ground a
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varying amount from casing to casing, the distance that the wellbore casing
extends above the
ground my be determined and taken into consideration when determining the
depth that the cut
must be made at to ensure that the casing and liner is removed up to the
predetermined amount.
For example, if the well casing extends 0.5 metres above the ground, the depth
of the cut must be
set at 2.5 metres to ensure that the casing may be removed up to a mandated
2.0 metres below
the surface. To allow for adjustability of the depth of the cut, the UHP
cutting device 30 may
include a depth adjustment block 13, one embodiment of which is shown in
Figure 1. The depth
adjustment block 13 is shown as being connected to the housing 9. The depth
adjustment block
9 is longitudinally adjustable along the length of the housing 9 so that the
depth of the cut may
be preset. Once adjusted, the depth adjustment block 9 rests on the top
surface of the well casing
with the cutter head 21 extending downward into the casing and presenting the
focus tube 23 at
the desired depth. Optionally, the depth adjustment block 9 may include size
extension rods as
shown in Figure 5 to expand the diameter over which the depth adjustment block
9 may rest. It
will be appreciated that the depth adjustment block 9 may be of various
configurations and may
be adapted to connect or rest upon various components of the ground
surrounding the casing or
elements within the casing, so long as the depth adjustment block 9 is of
sufficient strength and
sturdiness to hold the cutter head 21 at a consistent depth during rotation of
the UHP tube 4.
The end of the focus tube 23 should ideally remain at a consistent distance
from the internal
surface of the wellbore during rotation of the cutter head 21. In other words,
the cutting device
30 should ideally be centered in the wellbore. A centralizing device may be
included with the
cutting device 30 to automatically center the UHP tube 4 in the wellbore so
that during rotation
of the UHP tube 4, the end of the focus tube 23 remains and a consistent
distance from the inner
surface of the wellbore, assuming the wellbore is round.
In addition to Figure 1, the components of one embodiment of a centralizing
device are also
shown in Figures 3 and 4. This embodiment of a centralizing device includes a
centralizer
mounting bracket 14 connected to the housing 9 that serves to connect a
centralizer rod system
15 to the stationary housing 9. The centralizer rod system 15 comprises an
expandable web-like
system of rods and hinged joints, where, upon operation of centralizer
adjustment rods 12, the
diameters of the centralizer rod system 15 uniformally expands until it
touches the inner surface
of the wellbore thereby centering the housing 9 and the UHP tube 4 in the
wellbore. Expansion
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of the centralizer rod system 15 is controlled by the longitudinal sliding of
the centralizer
adjustment block 11 along the longitudinal axis of the housing 9. Sliding the
centralizer adjust
block 11 downward, pushes the centralizer adjustment rods 12 downward and
forces the rods and
hinged joints of the centralizer rod system 15 expand outwards. The
centralizer rod system 15
should be expanded until all outside rods of the centralizer rod system 15
touch the inner surface
of the wellbore thereby centering the UHP tube 4 in the center of the wellbore
liner or casing.
Once the centralizer rod system 15 has been expanded to the point where the
outside rods touch
the inner surface of the wellbore, the locking handles 10 on the centralizer
rod system 15 are then
tightened. Each handle 10 pulls on one of the centralizer adjustment rods 12
and expands the
centralizer more fully to create a better compression against the inner
surface and locks the
system in place. It will be appreciated that any type of locking system may be
used to secure the
centralizer adjustment block in place so that, once centered, the UHP tube 4
may be rotated
without displacing the UHP tube 4 from the center of the wellbore casing or
liner. It was also be
appreciated that the centralizer rod system 15 may comprise any suitable
number or setup of rods
and hinges so that expansion of the rods against the inner surface of the
wellbore casing or liner
centers the UHP tube 4 in the wellbore casing or liner.
With respect to the abrasive that may be used, one example is a garnet
abrasive. The size of
garnet usually ranges from 30 grit, 50 grit and 80 grit sizes. The 50 grit
size is generally used as
this seems to give an ideal cut to wear ratio to the cutter heads and focus
tubes. The smaller 80
grit will cut and create less wear on the consumables but takes a much longer
time to cut. The
larger 30 grit will cut faster but causes the cutter head and focus tubes to
wear more quickly.
Example of Operation of the Cutter Device
It will be appreciated that the following example of the operation of the
cutting device is merely
an example of one method of operating the cutting device and should not be
interpreted as
limiting or the soul method of operating the device. The order of steps
outlined below is not
essential to the successful operation of the device. Variations may be made to
the techniques,
steps and order that are encompassed in the concept of operation of the
cutting device. None of
the steps below are to be considered limiting and are merely illustrative of
one method of using
one embodiment of a cutting device.
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Once at the site at which the wellbore casing and/or liner is to be removed,
the wellhead is
removed. This is done by removing the bolts that hold the wellhead to the
casing bowl. The
casing bowl is welded to the well casing that extends down into the ground.
After removing the wellhead, a measuring device is used to determine the exact
size of the inside
diameter of the smallest casing string that needs to be cut. The measurement
is needed to be able
to set up the cutter head for the proper size. Once the correct size is
determined, a chart that has
been developed (shown in Table 1 in Figure 7) may be consulted, to select the
proper length of
focus tube to be used, as well as the location for placement of the cutter
head assembly on the
manifold. By changing lengths of focus tubes and selecting different diameter
ports on the
manifold, virtually any production casing ranging from 4" to 16" inside
diameter may be cut.
The cutter head is assembled and the abrasive feed port is attached to the
side of the cutter head
and the abrasive feed line is connected to the cutter head.
In the chart shown in Figure 7, the first letter given in the cod column
represents the aperture
used. The letter E indicates if an extension head is used to connect the
cutter head to the
aperture. Letters ID indicate if the cutter head with optional extension head
extend across the
manifold and the other apertures or OD meaning that the cutter head with
optional extension
head extend out side the manifold directly without covering the other
apertures. For example,
AEID means an extension head is used that is connected to the cutter head and
aperture A
extending across apertures B and C. AID means that the cutter head is
connected directly to
aperture A and extends across aperture B and C. B means that the cutter head
is connected
directly to aperture B. AEOD means that an extension head is used connected to
aperture A and
extends directly out from the manifold without covering the other apertures.
In addition, the
length of focus tube is also indicated. For example, a focus tube may be of
any suitable length,
however, the length of focus tube for this example may be between 1.5 and 3
inches as indicated
in the chart.
After the cutter head and manifold assembly is prepared, the system is
pressure tested to check
for leaks. If leaks are present, the unit is reassembled to fix any leaks or
problems.
The needed depth of the cutter head may be determined by measuring the height
that the casing
extends above the ground and adding this to the usual 2 metres that is
required below surface. If
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1
0.5 metres is above ground, the depth is set to 2.5 metres. The depth is set
by setting the depth
adjustment block to the desired location.
To lower the tool into the well, a small block and tackle assembly is used,
which is attached to
the bucket of a backhoe. The bucket is raised above the well and the tool is
lifted straight up
above the casing string and then lowered slowly, by hand using the pulley
system, into the inner
casing string. Attention should be taken to be very careful not to strike the
focus tube against the
side of the casing as it is being lowered inside, to prevent breaking or
bending the focus tube.
Once the tool has been lowered into the casing, the tool is visually centered
at the top of the
casing. Next, the centralizer rod system is adjusted to the correct size by
moving the centralizer
adjustment block to the proper location and locking it into position by
tightening a bolt which
holds it fast to the hollow aluminum tubing. The handles are then compressed,
which pulls on the
centralizer adjusting rods, expanding the centralizer rods. This centres the
cutter head inside the
casing and prevents the cutter head from hitting the side of the casing as it
rotates inside while
cutting.
Next, the hydraulic lines are attached that come from a hydraulic pump inside
of the truck unit to
the hydraulic motor at the top of the cutting tool. The abrasive feed line is
then attached that
comes from the cutter head, to the abrasive pot inside the truck. The abrasive
that is fed to the
cutter head is pulled through the line by a suction which is created by water
passing over the
abrasive feed port at the cutter head.
The UHP water supply hose from the main pump is then connected to the UHP
connection at the
top of the cutting device.
When all connections are made, the UHP pump and diesel-powered engine are
started along with
the hydraulic pump unit. All systems are allowed to idle for several minutes
to warm-up before
being brought to operating speed.
When the units have been properly warmed up, the unit is brought to full
operating pressure by
activating a remote system that is attached to the main pump/engine assembly.
The water
pressure builds quickly through the system due to the orifice at the junction
of the cutter head
and UHP elbow, which comprises a 90 angle, at the bottom of the cutting
device. A water
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pressure of 43,500 psi is suitable for cutting both cement and stainless
steel. This pressure may
be controlled by a computer module that can be supplied with the engine/pump
assembly.
Once the system reaches the required pressure the abrasive feed line from the
cutter head to the
abrasive pot is checked for suction. If there is sufficient suction on the
line, a valve is opened on
the pot which allows the abrasive to flow from the pot to the cutter head.
When the abrasive reaches the cutter head, it is mixed with the water and
carried by the water,
through the focus tube. The abrasive does the majority if not all of the
actual cutting of the steel
and cement. The fluid, namely water, delivers the abrasive to the target.
After the unit reaches pressure and the abrasive is being fed through the
cutter head, the operator
activates the hydraulic control. Using a lever the operator may control the
movement of the
hydraulic motor forward or reverse. This in turn rotates the gear reduction
unit. The gear
reduction unit attaches to the UHP stainless steel rod and in turn, rotates
the cutter head at the
bottom of the cutting tool, moving slightly in either direction until the
abrasive pierces the casing
and cement, if present. Once the layers of steel casing and cement have been
pierced, the
operator may leave the hydraulic control lever in the forward position.
The forward speed of the hydraulic motor may be determined by a bypass needle
valve that is
manually adjustable. As the needle valve is opened, more hydraulic fluid
passes through the
system and increases the speed of the motor and the rotation of the cutter
head inside the well.
Closing the needle valve reduces flow to the hydraulic pump and in turn slows
the speed of
rotation of the cutter head.
It should be noted that if the cutter is turning too fast, a complete cut of
the layers of steel casing
and cement may not occur. In cases where larger outer casings are present,
along with multiple
layers of steel casing and cement, the speed of rotation should be reduced in
some cases to one
revolution in 45 minutes. In cases where only 1-2 layers are present, the
speed may be increased
to one revolution in 3 minutes. If the rotation of the cutter head is too fast
the cut is not complete.
If the rotation of the cutter head is too slow, materials and supplies are
wasted. It is
recommended that there be constant monitoring by the operator during the
cutting process.
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When the cut is complete, the operator closes the valve on the abrasive pot to
stop flow of the
abrasive feed to the cutter head. This allows for all material to be suctioned
through the abrasive
feed line preventing clogging of the system. After the line is empty, the
operator places the pump
and engine to idle speed and removes all water pressure from the system. The
pump and engine
may then be shut down. All water, hydraulic, and abrasive feed lines may be
disconnected.
The locking handles may be released and the centralizer system may be loosened
and the cutter
system connected by a lifting strap to the block and tackle system. The cutter
system may then
be lifted slowly from the casing and sprayed to remove dirt and grime that has
built up during the
cut. When the unit is completely out of the well, it may be lowered for
transport.
The cutter head system may then be disassembled and cleaned, being sure to
remove all traces of
abrasive from the focus tube and cutter head assembly. The centralizer system
may be cleaned
of all debris and lubricated and inspected for ease of movement. All moving
parts may be
thoroughly cleaned.
The cut casing/wellhead from the ground may removed by any suitable means such
as a backhoe
to shake and or rotate the casing to loosen it from the earth. Next a sling
may be attached and the
casing pulled from the ground. A plug assembly may be inserted into the top of
the casing string
that is left below ground and the hole left after the extraction, may be
filled with dirt.
It will be appreciated that the embodiments, components, methods and uses
outlines above are
merely illustrative of embodiments of the invention and are not intended to be
limiting in any
way. Modifications may be made to the embodiments, components, methods and
uses without
departing from the contemplated invention.
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