Note: Descriptions are shown in the official language in which they were submitted.
CA 02879588 2015-01-26
TITLE
[0001] METHOD AND APPARATUS FOR ABANDONING OR ISOLATING AN
UNDERGROUND PIPELINE
TECHNICAL FIELD
[0002] This relates to a method and apparatus for abandoning or isolating
an underground
pipeline under normal operating pressures.
BACKGROUND
[0003] Pipeline networks are installed in order to transport fluids
produced from wells to
a central location, such as for transportation or processing. Once a well is
no longer
producing, the pipelines may need to be abandoned. There may be other reasons
for isolating
or abandoning a pipeline. Pipeline abandonment or isolation can be an
intensive process,
often requiring excavation by heavy equipment, extensive depressurization
processes, and
welding. As the pipeline will generally be pressurized with volatile
compounds, time and
care must be taken, which increases the time and cost requirements.
SUMMARY
[0004] According to an aspect, there is provided a method of abandoning
or isolating a
section of a pipeline. The method comprises the steps of exposing the section
of the pipeline
to be abandoned, hot tapping the section of the pipeline to form an opening
while maintaining
the pressure in the section of the pipeline, injecting a formable plugging
material through the
opening to form a sealing plug in the section of the pipeline, and releasing
the pressure in the
section of the pipeline.
[0005] According to another aspect, the plugging material may be an epoxy,
a resin, or a
polymer.
[0006] , According to another aspect, the method may further comprise the step
of forming
an anchor in the pipeline that engages the plug to support the plug within the
section of the
pipeline.
[0007] According to another aspect, forming an anchor may comprise
deforming the
pipeline inward while forming an opening during hot tapping.
[0008] According to another aspect, forming an anchor may comprise
crimping the
pipeline on the sealing plug to enhance the seal of the sealing plug.
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[0009] According to another aspect, the method may further comprise the
step of
inserting a cleaning nozzle to clean the pipeline internally.
[0010] According to another aspect, the method may further comprise the
step of
injecting an inert gas to pressure test and clear debris prior to injecting
the formable plugging
material.
[0011] According to another aspect, the pipeline may have one of a 2 inch
diameter, a 3
inch diameter, and a 4 inch diameter.
[0012] According to another aspect, the plug may maintain up to a 450 psi
pressure
differential between a production side and an abandoned side.
[0013] According to an aspect, there is provided a combination of a hot
tapping tool
adapted to hot tap a section of a pipeline to form an opening while
maintaining the pressure in
the section of the pipeline, and an injector adapted to inject a formable
plugging material
through the opening to form a sealing plug in the section of the pipeline.
[0014] According to another aspect, the plugging material may be an
epoxy, a resin, or a
polymer.
[0015] According to another aspect, there may be a camera for determining
the degree of
cleaning required in the pipeline.
[0016] According to another aspect, there may be a jet nozzle for
cleaning the pipeline
internally.
[0017] According to another aspect, there may be a source of inert gas
connected to
pressurize the hot tapping tool.
[0018] According to another aspect, the pipeline may have one of a 2 inch
diameter, a 3
inch diameter, and a 4 inch diameter.
[0019] According to another aspect, there may be a tool for deforming the
pipeline to
form an anchor for anchoring the plug within the pipeline.
[0020] According to another aspect, there may be a source of formable
plugging material
connected to the injector.
[0021] According to another aspect, there may be a tool to cut a segment
from an
abandoned section of a pipeline for terminating and detaching the abandoned
section of the
pipeline from a remaining section of the pipeline.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0022] These and other features 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 be in any way limiting,
wherein:
FIG. 1 is a representative schematic of a pipeline to be abandoned.
FIG. 2 is an alternative representative schematic of a pipeline to be
abandoned.
FIG. 3 is a perspective view of a tool for abandoning a pipeline.
FIG. 4 is a perspective of the modified split tee.
FIG. 5 is a side elevation view of a tool being inserted into the pipeline.
FIG. 6 is a side elevation view in section of a nozzle for breaching the
sidewall of
the pipeline.
FIG. 7 is a side elevation view in section of a piston and cylinder.
FIG. 8 is a perspective view of a hydraulic press attachment.
FIG. 9 is a side elevation view of a camera being inserted into the pipeline.
FIG. 10 is a side elevation view of a nozzle being inserted into the pipeline.
DETAILED DESCRIPTION
[0023] A method and apparatus for abandoning or isolating a section of
pipeline will now
be described with reference to FIG. 1 through 10. While the discussion below
is in terms of a
section to be abandoned, it will be understood that similar tools and steps
may be used with
respect to a section to be isolated.
[0024] Referring to FIG. 1, a pipeline 10 is shown that has a section 12
to be abandoned,
and a remaining portion 14. The abandoned portion 12 connects to a source 16
of material to
be transported in pipeline 10. Source 16 may be, for example, an oil or gas
well that is no
longer producing or that is being produced into a separate container. Pipeline
10 may be, for
example, a buried pipeline intended to transport natural gas from a producing
well and may be
transporting the natural gas to a refinery or processing plant. Generally,
this type of pipeline is
a 2 inch pipeline, although other sizes may also be used in rare
circumstances, such as a 3
inch pipeline. The method described herein may also be applied to other types
of pipelines
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that are being abandoned.
[0025] Referring to FIG. 3, a hot tapping tool, generally indicated by
reference number
26, is first attached to pipeline section 12 at the point where the seal or
plug is to be initiated.
In order to hot tap pipeline section 12, hot tapping tool 26 provides a seal
against pipeline
section 12 and creates a sealed working space between pipeline section 12 and
hot tapping
tool 26. As is known in the industry, hot tapping tool 26 must be designed to
withstand the
pressures and fluids within pipeline section 12 as it will be exposed to these
pressures and
fluids. While a particular hot tapping tool is shown in the drawings and
described in greater
detail below, it will be understood that other designs for hot tapping tools
may equally be
used. Referring to FIG. 5, once properly installed, hot tapping tool 26
creates an opening 18 in
pipeline section 12. The size of opening 18 must be selected to prevent
compromising the
structural integrity of pipeline section 12, while still permitting the
injection of the formable
plugging material. There may be a source of gas connected to pressurize the
hot tapping tool,
which may be used to pressure test the seal of hot tapping tool 26 against
pipeline section 12
prior to breaching the pipe. Once opening 18 is formed, a blast of the high
pressure gas, or an
alternate cleaning product may be used to clear debris from the internal
portion of the pipe
prior to injecting the plugging material. Preferably, the gas is inert, such
as nitrogen. The
cleaning product may be a degreaser, solvent, water, or other fluid as will be
recognised by
those skilled in the art. Next, hot tapping tool 26 is used to inject a
formable plugging
material through opening 18 to form a sealing plug 20 within pipeline section
12. Sealing plug
20 preferably has a length in the axial direction of between two and four
feet, although it will
be understood that this length may vary depending on the application. The
material must be
capable of being injected in a fluid or formable state, and set to a solid or
plugging state in the
conditions present in pipeline section 12. This may include the presence of
fluids, such as
water, any remaining cleaning solution, hydrocarbons in a liquid or gas phase,
or solids such
as sand or scale. The proper formulation for this material can be determined
by a person of
ordinary skill and may include various materials such as epoxy, resin, or
polymer materials.
Preferably, the plugging material will form a plug that is solid and not
appreciably
compressible. In aid of this, it is preferred to inject the plugging material
in a manner that
does not allow air pockets to form.
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[0026] In order to ensure sealing plug 20 is stationary, an anchor is
used. One example of
anchoring sealing plug 20 is to form a crimp 22 in pipeline section 12 on plug
20. This may
also be used to enhance the seal between plug 20 and the inner wall of
pipeline 12. As shown,
crimp 22 is preferably spaced toward the end of plug 20 closest to the
abandoned well 16.
5 This is because, once abandoned, plug 20 and crimp 22 must withstand the
pressure from
pipeline 14. Crimp 22 may be a 1/2 inch impression on the top and the bottom
of the pipe.
Alternatively, an anchor may also be formed as pipeline section 12 is
breached. For example,
if a piercing tool is used that breaches pipeline section 12 in response to a
compressive force,
pipeline section 12 will be deformed inward as the sidewall may bend slightly
under the
compressive force, and the sidewall material may be compressed and torn by the
piercing tool
as it breaches pipeline section 12. In some circumstances, this deformation
may provide a
sufficient anchor for plug 20.
[0027] Each of the steps described above are preferably performed from
the ground level.
In a preferred embodiment sealing plug 20 will be able to maintain a 450 psi
pressure
differential between the production side of plug 20 and the abandoned section
12 without
movement of plug 20 or loss of sealing capability. This allows remaining
portion 14 to
continue to be operated after abandoned section 12 has been removed. Remaining
portion 14
may commonly be operated at 5 psi to 120 psi, however, it is preferred that
plug 20 meet the
300 ANSI (American National Standards Institute) standard as generally
required by industry.
[0028] Once properly plugged, the pressure in abandoned section 12 may be
released and
any remaining fluid may be removed, such as through a vent 24. The actual
venting and
draining method will depend on the materials within pipeline section 12.
[0029] While methods of hot tapping pipelines are known in the industry,
an example of
a suitable hot tapping tool 26 will now be described with reference to FIG. 3.
Modifications
may be made by those skilled in the art. Tool 26 is applied to the abandoned
portion of the
pipeline 12. In order to attach to abandoned portion 12, tool 26 has a
gripping portion in the
form of a split tee 28, as shown in FIG. 4. Split tee 28 is capable of opening
to fit around
pipeline 10, and then closing to engage pipeline 10. Split tee 28 may fit
around pipeline 10 by
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any method known in the art, such as by using a hinged connection 30, as shown
in HG. 4, or
through assembly from two portions. Referring to FIG. 5, split tee 28 has a
seal 34 that
engages and seals between split tee 28 and pipeline section 12 to form a
chamber that is
isolated from atmosphere and that will maintain the pipeline pressure once
pipeline 12 has
been breached. Split tee 28 has an opening 54 within the seal 34 to provide
access to pipeline
section 12 in order to allow it to be opened and to allow the plugging
material to be injected.
Referring to FIG. 3, Hot tapping tool includes a housing 36 attached to split
tee 28 through
which the various tools may be manipulated during the hot tapping and
injection steps as will
be described below. Housing 36 is connected to split tee 28 by a lower valve
38. When
lower valve 38 is closed, the pressure from pipeline section 12 is isolated
from atmosphere
and housing 36 may be removed or attached as necessary. In one embodiment, a
motor 40
and gear 42 may be provided to allow housing 36 to be easily threaded onto and
off of lower
valve 38. Opposite the end that attaches to valve 38, housing 36 has a seal
44, such as a
packing element or other suitable seal that seals around an actuator rod 46
and maintains
pressure when housing 36 is attached to valve 38 in the open position, while
allowing actuator
rod 46 to move axially through housing 36 and valve 38. By attaching and
removing housing
36 with valve 38 in the closed position, different tools can be introduced
through valve 38, as
required. ,
[0030] Referring to FIG. 3, with split tee 28 properly installed on
pipeline section 12, a
breaching tool 48 is attached to actuator rod 46 and retracted into housing
36. Housing 36 is
then threaded onto split tee 28 and valve 38 is opened. Actuator rod 46 may
then be lowered
and manipulated to cause breaching tool 48 to breach the sidewall of pipeline
section 12. As
shown in HG. 5, breaching tool 48 is preferably a piercing tool that pierces
pipeline section
12 by applying a compressive force, such as by using a hydraulic press 50 as
shown in FIG. 8
that is designed to be attached to housing 36 and apply a downward force on
actuator rod 46.
Other breaching tools 48 may also be used, such as a drill bit (not shown). As
shown in FIG.
5, breaching tool 48 also preferably includes nozzles 52 that are used to
inject fluids, such as
an inert gas, cleaning solution, treating solution, etc. in order to clear
debris, clean the inner
surface, or otherwise prepare the inner surface to receive the plugging
material that will be
injected. This may be done simultaneously or in stages. Referring to HG. 6,
breaching tool
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48 may be a piercing jet nozzle that can be used to both pierce and clean
pipeline 10. The
inert gas may also be used to pressure test the seal between the hot tapping
tool 26 and the
pipeline portion 12 prior to breaching the pipeline 12 and injecting the
formable plugging
material.
[0031] Preferably, actuator rod 46 is hollow to allow fluid to be
injected through nozzles
52. Integrating these functions saves the need to attach and insert a separate
cleaning tool or
device. Separate tools may be used if necessary or depending on other
functions that may be
desired, such as an inspection camera. Once pipeline section 12 has been
breached and
cleaned if necessary, by piercing jet nozzle 48, tool 48 is retracted into
housing 36 and valve
38 is closed. Housing 36 can then be vented and removed and an injection tool
102 (FIG. 10)
may be attached to piston 56. In some circumstances, it may be necessary to
use a different
housing 36 or at least a different actuator rod 46, depending on the fluids
being injected
through rod 46. Alternatively, different injection strategies may be used with
a different
design of. hot tapping tool 26. For example, if a two-part polymer is
injected, it may be
necessary to keep the components separate until they are mixed at injection
tool 102.
Alternatively, passage through rod 46 may form part of the mixing process.
Referring to FIG.
7, a piston 56 within a cylinder 58 is shown, each of which is designed to
maintain separation
between two components of the sealing material. Between piston 56 and cylinder
58 seals 62
such as 0-rings, are provided to maintain separation between the two
components of the
sealing material. Under this design, a mixing nozzle 102 (FIG. 10) will then
be threaded onto
the bottom of piston 56 in order to fully mix and activate the components
prior to injection
into pipeline section 12. The components can be injected through ports 64 and
66, which flow
through to the mixing element of mixing nozzle 102 that is attached to piston
56. The amount
of sealing material 20 injected should be calculated as twice the volume of
pipe between main
pipeline 14 and breach 18 in pipeline portion 12 to be abandoned as sealing
material 20 will
flow equally in either direction from the injection site. The amount of
sealing material 20
should be calculated to be sufficient to fill branch 12 up to, but not into,
pipeline 14, and
preferably extends to within 3 inches or less of main pipeline 14, and
preferably within 1 inch
or less.
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[0032] Referring to FIG. 1, after pipeline 12 has been plugged it may be
desirable to
physically isolate the remaining leg 12 or wellhead 16. Accordingly, a portion
of pipeline 12
may be removed, and both ends capped with caps 60. When installing caps 60,
other
compounds, such as finishing, filling, or adhesive materials, may be applied,
as desired.
Operation:
[0033] Referring to FIG. 1, when it is determined that the source 16 of
material to be
transported in pipeline 10 will no longer be used and it is determined that
section 12 of
pipeline 10 will be abandoned, it is necessary to expose pipeline 10, such as
by excavating
using a "hydro-vac" tool, at a point near where the abandoned portion 12
connects to the
remaining portion 14, or at a convenient portion for isolating abandoned
portion 12 from
remaining portion 14, which will generally continue to be in use. This
requires abandoned
portion 12 to be plugged such that it can maintain production pressure on one
side of plug 20
and ambient or atmospheric pressure on the other side of plug 20. With the
exposed section of
pipeline 10, the section of pipeline 10 is hot tapped in order to form an
opening 18 in the
section of pipeline 10 while maintaining the pressure in the section of
pipeline 10. Various
methods of hot tapping are known in the art and may be used. Referring to FIG.
9, it is
preferred that a camera 100 is inserted into pipeline 10 in order to view the
interior of pipeline
10 and determine the degree of cleaning that is required in the pipeline in
order to provide a
clean sealing surface. After the pipeline is breached by tool 48, tool 48 may
be removed in
order for camera 100 to be inserted into pipeline 10. After the degree of
cleaning that is
required has been determined, piercing jet nozzle 48 may then be re-inserted
into pipeline 10
in order to clean pipeline 10 internally. Piercing jet nozzle 48 is connected
to a source of
water or solvent (not shown) and sufficient pressure is employed to dislodge
debris from the
interior of pipeline 10. Depending on the degree of cleaning required, it may
be necessary to
reinsert camera 100 and reassess the interior of pipeline 10 and provide
further cleaning with
piercing jet nozzle 48.
[0034] Referring to FIG. 1, after opening 18 is formed a formable
plugging material such
as a polymer or other appropriate material as known in the art is injected
through opening 18
in order to form a sealing plug 20 between the abandoned section 12 and the
remaining
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portion 14. Preferably, plug 20 has a length in the axial direction of two to
four feet, although
it will be appreciated by one skilled in the art that this length may vary
depending on the
application. Plug 20 is preferably anchored within pipeline section 12. An
anchor 21 may be
inherently formed in pipeline section 12 by the material that extends inward
due to the
deformation caused by breaching pipeline section 12 with piercing jet nozzle
48.
Alternatively, it may be done by crimping pipeline section 12 at a point along
plug 20, as
shown in FIG. 2. The amount of crimping required will depend on the
application and the
amount of pressure plug 20 will be required to withstand. Preferably, crimp 22
is an
impression on the top and the bottom of the pipeline that extends 1/2 inch
into the interior
diameter of the pipe and engages plug 20. This supports the plug by
compressing the plug 20
which will enhance the seal and secure the seal within the section of pipeline
10. In a
preferred embodiment the crimp 22 is made on the plug 20 near the end of plug
20 that is
closer to the abandoned section 12. It will be understood by one skilled in
the art that the
location of the crimp 22 may vary, but is made such that the plug 20 is
secured within the
section of pipeline 10.
[0035] Once plug
20 is secured the pressure is released from the abandoned section 12.
The pressure may be released, for example, by opening vent 24 and allowing the
abandoned
section 12 to equalize with atmospheric pressure. Any appropriate method of
releasing the
pressure and draining abandoned section 12 may be used. Abandoned section 12
may remain
attached to remaining section 14 or abandoned section 12 may be severed from
pipeline 10 at
a point on abandoned section 12 past plug 20 after pressure is released and
abandoned section
12 is drained. Plug 20 remains as part of pipeline 10 that is still in use.
[0036] 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.
[0037] The scope
of the following claims should not be limited by the preferred
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embodiments set forth in the examples above and in the drawings, but should be
given the
broadest interpretation consistent with the description as a whole.
