U.S. patent application number 11/761185 was filed with the patent office on 2008-12-11 for method and apparatus for lengthening a pipe string and installing a pipe string in a borehole.
This patent application is currently assigned to FRANK'S INTERNATIONAL, INC.. Invention is credited to Brennan Scott Domec, Pradeep Kumar Mallenahalli, Mark Alan Veverica, Charles Michael Webre, John Fletcher Wheeler.
Application Number | 20080302539 11/761185 |
Document ID | / |
Family ID | 40094793 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080302539 |
Kind Code |
A1 |
Mallenahalli; Pradeep Kumar ;
et al. |
December 11, 2008 |
METHOD AND APPARATUS FOR LENGTHENING A PIPE STRING AND INSTALLING A
PIPE STRING IN A BOREHOLE
Abstract
The present invention generally relates to a method and an
apparatus for connecting an add-on pipe segment to a pipe string to
lengthen the pipe string using friction stir welding. The pipe
string is suspended in a borehole using a spider or some other pipe
suspending device, and the lower end of the pipe segment is brought
into an abutting or nearly abutting relationship with the proximal
end of the pipe string positioned above the pipe suspending device
and above the rig floor. The friction stir welding machine is
brought to well center to weld the abutment or gap between the pipe
segment and the pipe string and join the pipe segment to the pipe
string to lengthen the pipe string. In one aspect, the method
includes friction stir welding an expandable pipe segment to an
expandable pipe string to form a lengthened expandable pipe string.
The pipe segment may be comprised of two or more pipe segments that
have been friction stir welded or conventionally welded to form a
pipe stand. After friction stir welding to lengthen the pipe
string, the lengthened pipe string is lowered into the borehole and
the proximal end of the lengthened pipe string is favorably
positioned to abut or nearly abut a new add-on pipe segment for
friction stir welding at the resulting abutment or gap. The
friction stir welding process provides a highly reliable pipe joint
for expansion.
Inventors: |
Mallenahalli; Pradeep Kumar;
(Broussard, LA) ; Domec; Brennan Scott;
(Lafayette, LA) ; Webre; Charles Michael;
(Lafayette, LA) ; Veverica; Mark Alan;
(Youngsville, LA) ; Wheeler; John Fletcher;
(Lafayette, LA) |
Correspondence
Address: |
STREETS & STEELE
13831 NORTHWEST FREEWAY, SUITE 355
HOUSTON
TX
77040
US
|
Assignee: |
FRANK'S INTERNATIONAL, INC.
Houston
TX
|
Family ID: |
40094793 |
Appl. No.: |
11/761185 |
Filed: |
June 11, 2007 |
Current U.S.
Class: |
166/380 ;
166/77.51 |
Current CPC
Class: |
B23K 20/1225 20130101;
E21B 43/10 20130101; E21B 19/16 20130101; E21B 43/103 20130101;
B23K 2103/04 20180801; B23K 20/14 20130101; B23K 2101/06
20180801 |
Class at
Publication: |
166/380 ;
166/77.51 |
International
Class: |
E21B 19/16 20060101
E21B019/16 |
Claims
1. A method of lengthening a pipe string comprising the steps of:
suspending a pipe string from a rig using a pipe suspending device;
positioning a pipe segment having an upper end and a lower end to
be generally aligned with and in close proximity to or abutting the
proximal end of the pipe siring at its lower end; securing the
lower end of the pipe segment in close proximity to or abutting the
proximal end of the pipe string; and friction stir welding the pipe
segment to the pipe string to lengthen the pipe string.
2. The method of claim 1 further comprising the step of installing
the lengthened pipe string in a borehole and radially expanding at
least a portion of the pipe string within the borehole.
3. The method of claim 1 further comprising the step of securing
the pipe segment in its position in close proximity to or abutting
the proximal end of the pipe string by disposing an alignment clamp
to radially expand within a portion of the bore of the pipe segment
and a portion of the bore of the pipe string to grip the adjacent
ends of the pipe segment and the pipe string.
4. The method of claim 1 further comprising the step of securing
the pipe segment in its position in close proximity to or abutting
the proximal end of the pipe string by disposing a first external
clamp to close on and grip the lower end of the pipe segment and
disposing a second external clamp to close on and grip the proximal
end of the pipe string.
5. The method of claim 3 further comprising the step of axially
adducting a first gripping portion of the alignment clamp toward a
second portion of the alignment clamp to apply a preload to the
abutment between the pipe segment and the pipe string before
friction stir welding the pipe segment to the pipe string.
6. The method of claim 4 further comprising the step of axially
adducting a the first external clamp toward the second external
clamp to apply a preload to the abutment between the pipe segment
and the pipe string before friction stir welding the pipe segment
to the pipe string.
7. The method of claim 2 further comprising forcing an expansion
mandrel having a diameter greater than the interior bore of the
pipe string through the bore of the pipe string to radially expand
the pipe string within the borehole.
8. The method of claim 2 further comprising rotating a rotary
expansion tool within the pipe string to expand the pipe string
over a substantial portion of its length after the pipe string has
been substantially installed within the borehole.
9. The method of claim 1 further comprising the step of forming the
proximal end of the pipe string for mating engagement with the
lower end of the pipe segment to resist radial movement of one
relative to the other during friction stir welding.
10. The method of claim 1 further comprising the step of powering a
friction stir welding machine using pressurized fluid.
11. The method of claim 1 further comprising the step of powering a
friction stir welding machine using electricity.
12. The method of claim 1 further comprising the step of
pre-assembling the pipe segment to be joined to the pipe string
from a plurality of shorter pipe segments joined by a process
selected from the group of consisting of conventionally welding the
segments, friction stir welding the segments, or a combination of
one or more of these processes.
13. The method of claim 1 wherein the pipe suspending device is
selected from a group consisting of a spider, a set of landing
tables, a collar load support device, a dual elevator system used
in conjunction with landing tables, or some combination of
these.
14. The method of claim 1 further comprising the step of repeating
the first four steps until the pipe string achieves the desired
length, installing the pipe string in a borehole, and securing the
pipe string in place by circulating a cement slurry or a cement
substitute into the annulus between the exterior surface of the
pipe string and the wall of the borehole.
15. The method of claim 1 further comprising the step of
introducing a volume of fluid into the lengthened pipe string to
prevent collapse or damage to the lengthened pipe string as it is
lowered into a borehole.
16. The method of claim 1 further comprising the step of providing
a mating interface to the abutting ends of the pipe segment and the
pipe string to resist radial movement of one relative to the other
after an abutment is formed.
17. The method of claim 15 further comprising the step of
circulating the introduced fluid through the borehole by imposing a
seal between the fluid conduit and the interior wall of the
lengthened pipe string.
18. An apparatus for joining a pipe segment to a pipe string
comprising: a clamping assembly having a first clamp for gripping a
pipe segment and a second clamp for gripping a pipe string, the
first clamp being generally aligned with the second clamp; a
friction stir welding machine coupled generally intermediate the
first clamp and the second clamp for radially disposing a rotatable
probe into an abutment or a gap between a lower end of the pipe
segment and a proximal end of the pipe string; and an orbital
movement assembly for moving the rotatable friction stir welding
probe in a generally orbital path through the abutment or gap to
create a joint between the pipe string and the pipe segment to
lengthen the pipe string.
19. The apparatus of claim 18 wherein the friction stir welding
machine is movably suspended within a frame that can be moved to
the pipe string and supported on a rig floor.
20. The apparatus of claim 19 wherein the friction stir welding
machine is powered by a motor operated with pressurized fluid.
21. A method of joining a pipe segment to a pipe string on a rig
comprising the steps of: suspending a pipe string from the rig
using a pipe suspending device, a proximal end of the pipe string
protruding generally upwardly from the pipe suspending device;
positioning an add-on pipe segment into alignment with the pipe
string; abutting a lower end of the pipe segment against the
proximal end of the pipe string; clamping the pipe string and the
pipe segment to restrain the pipe string and the pipe segment in
the abutting position; and friction stir welding the abutment
formed between the pipe string and the pipe segment to lengthen the
pipe string.
22. The method of claim 21 further comprising the steps of: lifting
the lengthened pipe string to unload the pipe suspending device;
lowering the lengthened pipe string from the rig; and suspending
the lengthened pipe string from the rig by reengaging the pipe
suspending device.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to apparatus and methods for
lengthening a pipe string using friction stir welding and for
installing a friction stir welded pipe string in a borehole.
Specifically, the present invention relates to using friction stir
welding to join a pipe segment to a pipe string that is suspended
from a rig by a suspending device such as a spider, a landing
table, a collar load support device, or other devices known in the
art for suspending a pipe string from a rig.
[0003] 2. Description of the Related Art
[0004] Conventional pipe strings that are installed in a borehole
generally comprise pipe segments, typically 30 to 60 feet in
length, threadedly connected to form a pipe string that can extend
up to 10,000 feet or more. The pipe segments of conventional pipe
strings are connected using threaded connections including an
internally threaded sleeve that threadedly receives a first
externally threaded pipe end into its first end and a second
externally threaded pipe end into its second end to connect the two
pipe ends together to form a pipe string. The pipe string is
lowered through a rig floor into a borehole and suspended at the
rig floor using a suspending device, such as a spider. The proximal
end of the pipe string is positioned above the suspending device to
facilitate the connection of additional ("add-on") pipe segments to
the pipe string, after which the lengthened pipe string is lowered
further through the rig floor. This process is repeated until the
pipe string reaches the desired length for being installed in a
borehole and cemented into place, or otherwise applied for its
purpose.
[0005] Except for drive pipe and conductor casing installed near
the surface of a well, welding has not been practically used for
forming long pipe strings for use in drilling, production or
completion activities. Conventional welding, as that term is used
herein, generally refers to those welding processes that can be
referred to as fusion welding, such as electric arc welding.
Conventional welding is an alternative method of connecting pipe
segments to form a pipe string. For example, conventionally welded
connections are used to connect pipe segments into pipe strings to
form pipelines that can be used for transporting liquids or gas.
Pipe segments are generally distributed along the route of the
pipeline, and multiple conventional electrical arc welding machines
are used to join the ends of adjacent pipe segments to form a
continuous pipeline.
[0006] Conventional welding of long pipe strings suitable for use
in connection with drilling, completion and production activities
is not practical because the pipe string, which is generally
vertically suspended at the suspending device, must be formed by
joining one vertical add-on pipe segment (or stand) at a time to
lengthen the pipe string, lowering the lengthened pipe string
through the rig floor, and then repeating the process until the
pipe string reaches its desired length. This process enables the
positioning of the proximal end of the pipe string above the
suspending device (such as a spider) that suspends the pipe string
from the rig so that an add-on pipe segment can be welded to the
proximal end of the pipe string to lengthen the pipe string.
Conventional welding limits the rate of fabrication of a pipe
string because, compared to assembling a pipe string using threaded
connections, conventional welding is a slow process that may take
up to 60 minutes or more to complete the weld required at each
individual pipe joint, and also because the vertical orientation of
the proximal end of the pipe string, and of the add-on pipe segment
to be conventionally welded to the pipe string, allows welding of
only one pipe joint at a time. Since a threaded pipe connection can
be made-up much faster than a non-threaded connection can be
conventionally welded, these limitations make the assembly and
installation of a pipe string by conventional welding uneconomical.
The opportunity cost of the rig makes using conventional threaded
connections the far more attractive option, notwithstanding the
higher cost of the materials used to form each threaded joint.
[0007] Another problem with the use of conventional welding for
forming and installing a pipe string in a borehole is the
difficulty in obtaining welded pipe connections that are free of
weld defects and resistant to failure. Conventionally welded
connections include heat-affected zones ("HAZ's") that may, without
proper stress relieving, adversely affect the strength and
reliability of the welded joint. Although conventionally welded
joints may be stress relieved to eliminate detrimental HAZ's,
stress relieving would only increase the total amount of time
consumed in forming each pipe joint.
[0008] However, connecting pipe segments to form a pipe string by
welding remains desirable because the welded connection offers
advantages over a threaded connection. A welded connection is not
subject to the risk of unbucking ("backing off" by inadvertent
rotation), the welded connection is generally as strong as or
stronger than the pipe between the connections, a welded connection
is better suited to contain internal pressure without leaking, and
because the exterior of a welded pipe string does not have
shoulders that can hang up on borehole irregularities, such as
borehole protrusions and restrictions, and slow pipe string
installation. It is desirable to have the internal diameter and the
external diameter of the pipe joint as close as possible to the
internal diameter and the external diameter of the pipe body
between the pipe joints because this configuration uses less of the
borehole diameter for the pipe string, and because it allows a
larger section of the borehole to be drilled out through the pipe
string. Conventional connections consume a substantial amount of
radial space due to the radially overlapping configuration of
threaded connections. Also, for expandable pipe strings,
conventional threaded connections make expansion more difficult
since threaded sleeve connections offer substantially more
resistance to forced radial expansion than the portions of the pipe
wall between the threaded ends of the pipe. Threaded connections
that offer good sealing performance in their original state do not
reliably maintain the seal after being forcibly expanded or after
being installed in a high-temperature service environment. By
contrast, welded connections generally have mechanical properties
that are very close that those of the pipe material, and welded
connections generally expand uniformly with the adjacent pipe wall,
either from forcible expansion or from increased temperatures. As a
result, pipe strings having welded connections are easier to
install in a borehole through the bore of an existing pipe string,
and then more reliably expanded to nearly the same diameter as the
existing pipe string to form a "monobore" or a "nearly monobore"
pipe string. Wells drilled using a monobore well casing
construction approach offer a substantial cost savings over the
conventional pipe string multiple diameter technique because they
require substantially less pipe material and require substantially
smaller diameter boreholes compared to the conventional multiple
diameter casing string that requires a "telescoping" structure
formed by installing and connecting numerous progressively smaller
casing strings as the depth of the borehole increases. Monobore
casing strings may provide a substantial savings in drilling and
completion costs if welded pipe strings could be economically
welded and installed.
[0009] The monobore pipe strings described above are the subject of
several pending and issued patents. For example, international
applications WO 93/25799 (U.S. Pat. No. 5,348,095), WO 98/00626
(U.S. patent application Ser. No. 08/891,318) and WO 99/35368 (U.S.
patent application Ser. No. 09/223,996), the contents of which are
incorporated by reference, concern what is generally described in
the industry as "expandable-tube" technology for well construction
and borehole repair. Generally, expandable-tube technology enables
a smaller diameter pipe string to be formed and installed in a
borehole by passing it through the bore of an earlier-installed,
larger diameter pipe string, and thereafter expanded to a larger
diameter within the borehole. The expanded pipe string may serve as
a casing string or as production tubing through which hydrocarbons
are transported to the surface. Alternatively, the expandable pipe
string may be expanded against the inner surface of an existing
casing string to form a protective cladding for protecting the
existing casing string against corrosive well fluids and from
damage by tools that are lowered into the borehole for maintenance
and work-over operations.
[0010] There are some reported methods of forming and installing
expandable pipe strings using threaded connections, as opposed to
welded connections, to form monobores. International application WO
93/25799 (U.S. Pat. No. 5,348,095) discloses the joining of
expandable pipe strings having expandable threaded connections.
[0011] The advantage of using pipe strings made with threaded
connections over these alternative methods is that the pipe string
with threaded connections may be assembled on the rig to take any
form or length desired simply by joining pipe segments or other
devices on an as-needed basis. On the other hand, threaded
connections may not provide a fluid-tight seal, especially after
being expanded, and leaks at the joints may lead to undesirable
consequences. Another drawback to using threaded connections to
form and install expandable pipe strings involves the use of
expansion tools to expand the pipe string within the borehole. The
amount of force required to expand the threaded connection may be
far more than the adjacent pipe wall is capable of handling without
rupturing the pipe string. It would therefore be beneficial to
achieve a method of joining pipe segments that is not hindered by
threaded connections that expand differently than the adjacent
portions of the pipe string. The method should be generally quick
and safe to use on the rig floor, inexpensive to use, reliable, and
avoid the limitations of conventional welding processes.
[0012] Many attempts have been made to adapt conventional welding
to the formation of pipe strings in order to avoid the many
complications and problems that come with the use of threaded
connections. The difficulties presented by using conventional
threaded connections for expandable pipe strings prompted some to
experiment with different welding techniques for joining pipe
segments to form a pipe string. Conventional welding techniques
that have been considered are submerged arc welding, tungsten inert
gas welding and gas metal arc welding, among others. However,
safety does not generally permit conventional welding techniques
requiring an open ignition source at or near the borehole where
hydrocarbon gases could be ignited. For the same reasons, other
newer forms of welding such as electrical resistance welding,
radial friction welding, flash welding (U.S. Pat. No. 6,935,429),
metallurgical bonding (U.S. Pat. No. 6,860,420), explosive welding
(U.S. Pat. No. 6,953,141), amorphous bonding (U.S. Pat. No.
6,078,031), forge welding (U.S. Pat. No. 7,181,821) and laser
welding (U.S. Pat. No. 7,150,328) are also generally unacceptable
or impractical. These other newer forms of welding have individual
drawbacks associated with each technique including, but not limited
to, electrical spark generation, production of toxic fumes, visual
limitations due to involved arc flash, other sources of ignition,
workpiece pre-heating requirements, equipment limitations (cost,
size, etc), environmental restrictions (rain, moisture, wind,
humidity, etc.), lack of reliable weld quality, repeatability and
speed of weld production. Therefore, these other newer forms of
welding, like conventional welding techniques, are too risky to use
near a borehole.
[0013] A need exists for a method and an apparatus that employs
welding to connect pipe segments or stands together to form a pipe
string. A need exists for a method and apparatus for forming and
installing pipe strings that eliminates losses related to unbucking
of threaded connections. A need exists for a method and an
apparatus for joining pipe segments to pipe strings to form joints
that are as strong as or stronger than the pipe adjacent to the
pipe joint. A need exists for a method and an apparatus for forming
pipe strings that are better suited for containing internal
pressure, even after being expanded within a borehole. A need
exists for a method and an apparatus for joining pipe segments to a
pipe string on a rig that avoids the introduction of ignition
sources near the borehole.
SUMMARY OF THE INVENTION
[0014] The present invention satisfies one or all of the
above-stated needs, and others. Aspects of the present invention
provide an apparatus and a method of connecting pipe segments to
form a pipe string using friction stir welding. Friction stir
welding is described in U.S. Pat. No. 5,460,317, which is
incorporated herein by reference.
[0015] The present invention relates to a method and an apparatus
for lengthening a pipe string by using friction stir welding to
join add-on pipe segments to the pipe string while it is supported
within a borehole using a suspending device. The suspending device
used to suspend the pipe string within the borehole may be a
spider, a collar load support device, landing tables, a dual
elevator system with landing tables, or any combination of these or
other devices known in the art for suspending a pipe string from a
rig.
[0016] The apparatus for joining add-on pipe segments to a pipe
string comprises a friction stir welding machine having a rotatable
probe for being forcibly inserted into an abutment between the
lower end of the add-on pipe segment and the proximal end of the
pipe string, or into a gap between the nearly abutting and adjacent
ends of a pipe segment and a pipe string where the gap is
substantially smaller than the rotatable friction stir welding
probe. The friction stir welding machine further comprises an
assembly for movably securing the friction stir welding machine
into position for applying the force necessary to cause the
rotating probe to be inserted into the abutment or the gap and to
stir the material of the pipe segment and the pipe string
immediately adjacent to the abutment or the gap. The assembly may
include an internal clamp or an external clamp, or both, for
gripping and restraining the abutment or the gap between the add-on
pipe segment and the pipe string in a manner to oppose movement of
the pipe segment and the pipe string away from the rotating probe
during probe insertion. In one embodiment, the pipe segment and the
pipe string are both aligned and secured in the abutting or nearly
abutting position using an internal clamp that is inserted into,
and later withdrawn from, the top end of the pipe segment and
positioned at the abutment or gap between the two workpieces. In an
alternate embodiment, the friction stir welding machine may
comprise a clamp assembly that grips the exterior of the lower end
of the add-on pipe segment using a superior (upper) clamp, and that
grips the exterior of the pipe string under the proximal end of the
pipe string using an inferior (lower) clamp that is generally
aligned with the superior clamp. In one embodiment, a clamp
assembly applies a restraining force to the pipe segment and the
pipe string to maintain the abutment or the gap between the pipe
string and the add-on pipe segment. The clamp assembly may operate,
alone or in conjunction with other devices, to resist separation of
the pipe segment from the pipe string at the abutment or gap upon
forcible insertion of the rotating stir probe into the abutment or
gap.
[0017] In another embodiment, the clamp positions the pipe segment
to maintain a gap between the lower end of the pipe segment and the
upper end of the pipe string that is substantially smaller than the
rotatable pin, or probe, that engages and stirs the material of the
pipe segment and the pipe string to create the joint. While there
may be no specific advantage to creating a gap between the two
workpieces, it should be recognized that friction stir welding,
like some other methods of welding, does not necessarily require
abutment of the workpieces in order to join the workpieces. In one
embodiment, a spacer or insert may be used to establish or maintain
the desired gap.
[0018] In another embodiment, an internal clamp may be used either
in place of or with external clamps to align the pipe segment with
the pipe string, either to form an abutment or to form a gap
substantially smaller than the diameter of the rotating friction
stir welding probe. The internal clamp may be inserted into the
bore of the pipe segment and positioned to straddle the abutment or
the gap between the lower end of the pipe string and the proximal
end of the pipe segment. The internal clamp is expandable to grip
the pipe string and the pipe segment to maintain the abutment or
the gap and may also be designed to resist separation of the pipe
segment from the pipe string during friction stir welding. An
internal clamp may also be coupled to a source of inert gas for
displacing air from the vicinity of the friction stir welded joint
to prevent unwanted oxidation of the material that is heated by the
friction stir welding process.
[0019] In another embodiment, an internal alignment device may be
used to provide reinforcement to the wall of the pipe segment and
the pipe string to resist deformation under the large forces
applied by the friction stir welding probe as it is forcibly
inserted into the abutment or the gap, and as it is forced into the
abutment or the gap to join the pipe segment to the pipe string.
The internal alignment device may also be coupled to a source of
inert gas for displacing air from the vicinity of the friction stir
welded joint to prevent oxidation of heated material. The internal
alignment device may be especially useful in joining pipe segments
and pipe strings having a thin pipe wall that might otherwise
deform under the load applied by the friction stir welding
machine.
[0020] In another embodiment of the method of the present
invention, the lower end of the pipe segment and the proximal end
of the pipe string may be formed for mating engagement to resist
radial movement of one relative to the other during friction stir
welding. For example, the weld bevels on the lower end of the pipe
segment may be tapered to form the radially exterior surface of a
truncated conical frustum, and the weld bevels on the proximal end
of the pipe string may be reverse tapered to form the radially
interior surface of a truncated conical frustum so that the lower
end of the pipe segment may be received into the proximal end of
the pipe string to form an interface that is not purely horizontal
relative to the axis of the workpieces. This type of mating
interface is generally self-aligning; that is, the interface tends
to secure the pipe segment and the pipe string in the aligned
condition.
[0021] The friction stir welding apparatus of the present invention
may further comprise an orbital movement assembly that imparts
controlled orbital movement of the rotatable probe about the
abutment or the gap to provide a fully circumferential friction
stir weld. The orbital movement assembly may be hydraulically,
pneumatically or electrically-powered, or any combination thereof,
to forcibly move the friction stir welding machine, including the
rotatable stir probe, about the abutment or the gap. Similarly, the
clamp assembly described above may be hydraulically, pneumatically
or electrically-powered, or any combination thereof, to grip the
lower end of the add-on pipe segment with the superior clamp and
the proximal end of the pipe string with the inferior clamp. The
friction stir welding machine may be hydraulically, pneumatically
or electrically-powered, or any combination thereof, to rotate the
stir probe within the abutment or the gap while the orbital
movement assembly imparts orbital movement to move the rotating
stir probe through the seam to friction stir weld the add-on pipe
segment to the pipe string. In one embodiment, the orbital movement
assembly cooperates with an external clamp assembly, and the
superior clamp and the inferior clamp assist in supporting the
friction stir welding machine and in securing the orbital movement
assembly in position to forcibly impart the orbital movement to the
friction stir welding machine.
[0022] In one embodiment of the method of the present invention,
the pipe string lengthened using the method of the present
invention is expanded after being installed in the borehole. There
are several methods for expanding a pipe member after it is
installed within a borehole. In one embodiment, the present
invention provides an expansion mandrel for forcibly expanding the
pipe string as the mandrel is axially forced to move through the
bore of the lengthened pipe string. This method is described in
U.S. Pat. No. 5,348,095, which is incorporated by reference herein.
In another embodiment of the method of the present invention, the
pipe string is expanded within the borehole using a rotary
expansion device such as that described in U.S. Pat. No. 6,935,430.
An expandable pipe string formed using the method and apparatus of
the present invention may be expanded within the borehole while
maintaining a fluid-tight seal at the expanded friction stir welded
joints formed between adjacent pipe segments.
[0023] The joining of adjacent pipe segments utilizes a stir probe
formed of a material that may be substantially harder than the
material of the pipe segment and pipe string being joined, and by
rotating and forcibly inserting the probe into an abutment between
the pipe segment and the pipe string, or into a gap between the
adjacent ends of the pipe segment and the pipe string, to
plasticize and stir at least a portion of the material at the
adjacent ends of each of the pipe segment and the pipe string to
join the pipe segment and the pipe string into a lengthened pipe
string. The stir probe used to make the friction stir weld between
the pipe segment and the pipe string may be a tungsten-rhenium
alloy, a polycrystalline cubic boron nitride, or some other
material that is suitable for forcibly engaging and stirring steel,
steel alloys and other metals that can be used to form pipes.
[0024] In a preferred embodiment, the friction stir welding machine
cooperates with a clamp assembly to operatively secure the friction
stir welding machine into position to be moved in an orbital path
about the abutment or the gap between the lower end of the pipe
segment and the proximal end of the pipe string. In one embodiment,
the friction stir welding machine and the clamp assembly may
together be disposed within a frame that can be controllably
supported and moved on the rig floor, such as within a groove or on
a track, toward well center to engage the pipe segment and the pipe
string for joining them together, and later controllably moved away
from well center to remove the friction stir welding machine and
the clamp assembly, and to clear the rig floor for other activity.
The frame may be adapted for automated repetitive movement to and
from well center, and it may be remotely controlled.
[0025] In one embodiment, the friction stir welding machine may be
disposed within the bore of the pipe segment and positioned at the
abutment or the gap between the pipe segment and the pipe string to
join the lower end of the pipe segment to the proximal end of the
pipe string from the inside. This embodiment is more applicable to
larger diameter pipe, and can be used with either internal clamps,
external clamps, or a combination thereof, for gripping the pipe
segment and the pipe string, and for maintaining the abutment or
the gap between the pipe segment and the pipe string during the
friction stir welding process.
[0026] The method of the present invention uses the friction stir
welding process to provide a pipe string comprising a plurality of
joined pipe segments, the pipe string having a generally uniform
wall thickness at the welded connections that is substantially the
same thickness as the adjacent pipe wall, and highly reliable for
expansion, along with the non-welded portions of the pipe string,
to form an expanded pipe string having a larger diameter.
[0027] In one embodiment of the present invention, the method for
forming and installing a pipe string in a borehole using friction
stir welding includes the step of joining a pipe segment to a pipe
string by simultaneously using two or more friction stir welding
probes distributed about the abutting seam or the gap formed
between the lower end of the pipe segment and the proximal end of
the pipe string. This method includes the step of distributing the
rotatable friction stir welding probes about the abutting seam or
the gap, and simultaneously engaging and welding the abutment or
the gap using two or more rotating friction stir welding probes. In
one embodiment, the distributed friction stir welding probes are
distributed so as to generally balance the insertion forces
imparted to the abutting or nearly abutting pipe segment and pipe
string by the forcible insertion of the rotating probes to
mechanically stir the material of the pipe segment and the pipe
string adjacent to the abutting seam or the gap. Similarly, the
corresponding apparatus of the present invention comprises two or
more rotatable stir probes, each coupled to a press for forcibly
disposing the probe into the abutting seam or gap between the pipe
segment and the pipe string, and for controlled orbital rotation
about the abutment or gap to join the pipe segment to the pipe
string. The probes may be disposed and moved about the abutting
seam or gap while generally opposed one to the other to offset the
forces or, alternately, the probes may be staggered so that a first
probe preconditions the workpieces at or near the abutment or gap
to facilitate improved joining of the workpieces using the second,
or trailing, probe.
[0028] The number of friction stir welding probes that can be
simultaneously engaged with the workpieces may depend on the size
of the pipe and size of the friction stir welding machines, the
diameter of the weld being made and the desired proximity of the
rotating friction stir welding probes one to the others. It should
be noted, however, that two or more friction stir welding probes
may require a substantially increased amount of force to
controllably move the rotating probes through the abutting seam or
gap to join the workpieces.
[0029] It will be understood by those skilled in the art that the
methods and apparatus of the present invention are compatible with
the use of fill-up and circulation tools for intermittently
introducing fluid into the bore of the lengthened pipe string to
generally maintain a hydrostatic balance between the bore of the
lengthened pipe string and the annulus between the pipe string and
the wall of the borehole over the length of the pipe string. It
will also be understood by those skilled in the art that the
present invention may be used and implemented on a conventional rig
having a drawworks for supporting a block, and a string elevator
supported from the block, a top drive, or any other rig having a
vertically reciprocatable support for positioning a pipe segment or
for suspending and lowering a pipe string into a borehole.
[0030] The use of friction stir welding with the present invention
to join pipe segments to a pipe string offers many advantages that
cannot be achieved by using conventional welding. Friction stir
welding eliminates many safety hazards associated with conventional
welding such as open ignition sources, toxic fumes, weld spatter,
transportation of and connections to bottled or tanked industrial
gasses, and visual sensitivity of humans to the arcs produced
during conventional welding. Also, unlike with conventional
welding, the entire length of the pipe string does not become a
part of an electrical circuit with friction stir welding. Other
costly and time-consuming activities associated with conventional
welding are also eliminated, such as beveling of surfaces to be
welded, weldor training and skills certifications, preheating of
workpieces to a minimum temperature, and post-weld cooling of
workpieces to a maximum temperature prior to loading.
[0031] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. However, that the appended
drawings illustrate only typical embodiments of this invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an elevation view of a rig floor supporting a
spider that suspends a pipe string within a borehole and generally
aligned with and beneath a pipe segment suspended over the rig
floor. A power bundle having a first portion and a second portion
is shown generally circumscribing the pipe string.
[0033] FIG. 2 is the elevation view of FIG. 1 after the string
elevator is used to position the pipe segment to abut the proximal
end of the pipe string suspended in the borehole by the spider.
[0034] FIG. 3 is the elevation view of FIG. 1 with an orbital
friction stir welding machine positioned to join the pipe segment
to the pipe string at the abutment to lengthen the pipe string. An
externally gripping superior clamp and an externally gripping
inferior clamp of the friction stir welding machine, along with a
spider, are shown in cross-section.
[0035] FIG. 4 is the elevation view of FIG. 3 showing the orbital
friction stir welding machine as it begins to join the pipe segment
to the pipe string at the abutment to lengthen the pipe string.
[0036] FIG. 5A is an elevation view of the orbital friction stir
welding machine as it begins to orbit the abutment between the pipe
string and the pipe segment and progressively welds the
abutment.
[0037] FIG. 5B is an elevation view of the orbital friction stir
welding machine as it continues to orbit the abutment and to join
the pipe segment to the pipe string as the slack is pulled from the
power bundle to clear the rig floor.
[0038] FIG. 6 is an elevation view of the lengthened pipe string
after the friction stir welding machine has completed the weld of
the abutment and has been removed from well center. The lengthened
pipe string is shown as it is lifted vertically to unload the
spider.
[0039] FIG. 7 is an elevation view of the lengthened pipe string of
FIG. 6 illustrating the location of the top of the pipe string and
the location of the friction stir weld after the lengthened pipe
string has been lowered into the borehole to position the top end
of the lengthened pipe string for joining an additional add-on pipe
segment.
[0040] FIG. 8 is an elevation view of one embodiment of an
expansion mandrel for expanding a friction stir welded pipe string
formed using the method or apparatus of the present invention.
[0041] FIG. 9 is a perspective exploded view of one embodiment of a
rotary expansion tool that may be used to expand an expandable pipe
string formed using the method or apparatus of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0042] FIG. 1 is a partial cross-section view of a rig floor 14
supporting a spider 16 having slips 18 that engage and suspend a
pipe string 20 within a borehole 6 beneath a generally linear pipe
segment 22 that is suspended over the rig floor by an
externally-gripping elevator 23. Power bundle 57, having a first
portion 56 (that crosses in front of the spider 16 that is shown in
cross-section) and a second portion 54, is shown generally
circumscribing the pipe string 20. The string elevator 23 is
suspended from a block (not shown in FIG. 1) using bails 17, and
the string elevator 23 may be controllably raised and lowered using
a drawworks (not shown in FIG. 1) that supports the block. The pipe
segment 22 has an upper end 22a positioned above the string
elevator 23 and a lower end 22b disposed toward the rig floor 14.
The pipe segment 22 is generally positionable using the drawworks
and the string elevator 23 for being abutted or nearly abutted
against the proximal end 20a of the pipe string 20 that extends
above the spider 16. It should be understood that the pipe segment
22 and the pipe string 20 may each comprise a single pipe segment
or a plurality of pipe segments coupled together to form a longer
pipe segment. In one embodiment of the method of the present
invention, pipe segments may first be joined, for example, using
either friction stir welding, conventional welding, or any
combination thereof, to form pipe stands that are then positioned
above the rig floor 14 to abut or nearly abut the pipe string 20
and joined to the pipe string using friction stir welding to
lengthen the pipe string. It should be understood that the pipe
segment may be positionable using a top drive instead of the string
elevator supported from a block.
[0043] FIG. 2 is a partial cross-section view of the pipe string 20
and the pipe segment 22 of FIG. 1 after the string elevator 23 is
used to position the lower end 22b of the pipe segment 22 to abut
or nearly abut the proximal end 20a of the pipe string 20 suspended
in the borehole 6 by the spider 16. The resulting abutment 24 or
gap is positioned at a desired distance above the rig floor 14 for
being engaged and welded by a friction stir welding machine as
described in more detail below. The power bundle 57 remains
generally circumscribed about the pipe string 20 and unaffected by
the alignment and abutment 24 or near abutment of the pipe segment
22 and the pipe string 20. In one embodiment of the present
invention, the string elevator 23 may be accompanied by a body 25
also attached to the rig hook or top drive for being urged against
the top end 22a of the pipe segment 22 for resisting separation of
the pipe segment 22 away from the pipe string 20. The resisting
force applied by the body 25 to the pipe segment 22 may supplement
the resistance applied by at least a portion of the weight of the
pipe segment 22. In other embodiments, the resistance to separation
may be provided using internal clamps or external clamps, or a
combination of both.
[0044] FIG. 3 is a partial cross-sectional view of an orbital
friction stir welding machine 40 brought to well center generally
along the path 49 to engage the abutting or nearly abutting pipe
segment 22 and pipe string 20 and to join the pipe segment to the
pipe string at the abutment 24 or gap to lengthen the pipe string
20. The superior clamp 42a and the inferior clamp 42b of the clamp
assembly are shown in cross-section to reveal the relationship to
the abutment 24 or gap. The friction stir welding machine 40
comprises a motor 47 for rotating a stir probe 48, and a superior
clamp 42a and an inferior clamp 42b for securing the pipe segment
22 and the pipe string 20 in a generally aligned and abutting or
nearly abutting position, and also for movably securing the
friction stir welding machine 40 to the pipe segment 22 and the
pipe string 20, respectively, while maintaining the pipe segment
and the pipe string in the generally aligned and abutting or nearly
abutting position. The superior clamp 42a and the inferior clamp
42b comprise superior external gear 43a and inferior external gear
43b for engaging a superior orbital drive gear 46a and an inferior
orbital drive gear 46b, respectively, for controllably moving the
friction stir welding machine 40 about the abutment 24 or gap. The
power bundle 57 terminates at the power supply terminus 52 to
provide power to the friction stir welding machine 40. In another
embodiment, the resistance to separation at the abutment or gap may
be provided using an internal alignment clamp, such as the one
described in U.S. Pat. No. 6,392,193, that not only aligns the
lower end of the pipe segment with the proximal end of the pipe
string, but can also grip and restrain these ends in position.
[0045] FIG. 4 is a partial cross-sectional view of the orbital
friction stir welding machine 40 secured to the pipe segment 22 and
to the pipe string 20 to begin joining the pipe segment to the pipe
string at the abutment 24 or gap to lengthen the pipe string. The
superior clamp 42a and the inferior clamp 42b are shown in their
closed and clamping positions above and below the abutment 24 or
gap, respectively. The superior clamp and the inferior clamp close
on and grip the pipe segment and the pipe string, respectively, to
restrain the pipe segment and the pipe string in their abutting or
nearly abutting relationship and to oppose the forces imparted to
these two abutting or nearly abutting pipe members by the forcible
insertion of the rotating probe 48 into the abutment 24 or gap. The
superior clamp and the inferior clamp also provide substantial
torque resistance to the superior external gear 43a and inferior
external gear 43b to enable the orbital movement of the friction
stir welding machine 40 about the abutment 24 or gap and, more
specifically, of the stir probe 48 through the generally circular
seam that is the abutment 24 or gap by powered simultaneous
rotation of the superior drive gear 46a and the inferior drive gear
46b that engage and rotate against the superior external gear 43a
and the inferior external gear 43b on the exterior of the superior
clamp 42a and the inferior clamp 42b, respectively.
[0046] The motor 47 shown in FIGS. 3 and 4 is preferably a
hydraulically-powered motor that powers the rotation of the probe
48 as it stirs and plasticizes the material adjacent to the
abutment 24 or gap to friction stir weld the pipe segment to the
pipe string. The motor is driven to rotate using a supply of high
pressure hydraulic fluid delivered to the motor by a hose within
the power bundle 57. The fluid discharged form the motor 47 is
returned to the fluid reservoir (not shown) using a second hose
within the power bundle 57. The power needed to extend the probe 48
radially inwardly and to force insertion of the probe 48 into the
abutting seam 24 or gap may be provided using a gear and rack
assembly that extends, upon powered rotation of the gear, to force
the probe 48 radially inwardly to engage and be inserted into the
abutting seam 24 or gap. The extending gear and rack assembly for
providing probe insertion into the abutment 24 or gap may be
powered using the same source of high pressure hydraulic fluid used
to drive the motor 47 that rotates the probe 48.
[0047] When closed, the superior clamp 42a and inferior clamp 42b
prevent separation of the friction stir welding machine 40 from the
abutment 24 or gap as the probe 48 is powered by the extending gear
and rack assembly to penetrate the abutment 24 or gap and powered
by the motor 47 to rotate and stir the material of the pipe segment
and the pipe string. The powered rotation of the superior drive
gear 46a and the inferior drive gear 46b against the superior
external gear 43a and the inferior external gear 43b disposed on
the external surfaces of the superior clamp 42a and the inferior
clamp 42b, respectively, may be provided by one or more auxiliary
motors that may be driven using the same high pressure hydraulic
fluid supply provided to operate the motor to drive the probe.
Alternately, the powered rotation of the superior drive gear 46a
and the inferior drive gear 46b against the superior external gear
43a and inferior external gear 43b, respectively, disposed on the
external surfaces of the superior clamp 42a and the inferior clamp
42b may be provided by a gear train driven by the motor 47. The
power needed to forcibly close the superior clamp 42a and the
inferior clamp 42b and to thereby forcibly grip the pipe segment 22
and the pipe string 20, respectively, may be provided from the same
high pressure hydraulic fluid supply provided to drive the motor 47
to rotate the probe 48.
[0048] It should be understood that the closure of superior clamp
and the inferior clamp to grip the pipe segment and pipe string,
the rotation of the probe, and the rotation of the drive gears may
be mechanically enabled using a variety of power sources, including
hydraulic pressure, pneumatic pressure, electricity, mechanical
linkages, etc. It is preferred that these devices be
hydraulically-powered in order to eliminate spark-ignition sources
from the near-borehole area and also due to the need to deliver
generally high-density power to the friction stir welding machine.
While pneumatically-powered devices generally avoid or minimize the
potential for unwanted ignition sources, the motor and the
cylinders would need to be substantially larger to use compressed
air as the power fluid to generate the same clamping force, gear
torque, motor torque and speed, etc. However, it should be
recognized that modern intrinsically-safe or explosion-proof
electrical devices may be adapted for powering the various devices
of the apparatus of the present invention without introducing an
ignition risk.
[0049] FIG. 5A is an elevation view of the pipe segment 22 and the
pipe string 20 of FIGS. 1-4 illustrating the movement of the
friction stir welding machine 40 as it progresses from its
beginning position shown in FIG. 4 on its orbital movement about
the circumference of the abutment 24 or gap. The movement is
generally clockwise as viewed from the string elevator 23. The
probe 48 forcibly inserts into the abutment 24 or gap, and is
rotated by the motor 47 to friction stir weld the pipe segment 22
to the pipe string 20. The closed superior clamp 42a and the
inferior clamp 42b are closed to grip the pipe segment 22 and the
pipe string 20, respectively, to prevent separation of the probe 48
from the abutment 24 or gap. The powered rotation of the superior
drive gear 46a and of the inferior drive gear 46b against the
superior external gear 43a and the inferior external gear 43b,
respectively, result in controlled orbital movement of the friction
stir welding machine 40 about the abutment 24 or gap, and
controlled movement of the probe 48 through the entire circular
path of the abutment 24 or gap.
[0050] FIG. 5B is an elevation view of the pipe segment 22 and the
pipe string 20 of FIGS. 1-5A illustrating the continued movement of
the friction stir welding machine 40 as it progresses from its
position shown in FIG. 5A on its orbital movement about the
circumference of the abutment 24 or gap. FIG. 5B illustrates the
modified appearance of the portion of the abutment 24 or gap that
has been friction stir welded by rotation of the stir probe 48 as
the friction stir welding machine 40 continues on its orbit about
the abutment 24 or gap in the direction of the arrow 50'. The slack
in the power bundle 57 is shown to have been removed as the
friction stir welding machine 40 orbits the abutment 24 or gap.
[0051] FIG. 6 is an elevation view of the pipe string 20 (now
including the pipe segment 22) after the friction stir weld has
been completed and the pipe string and the pipe segment have been
joined at the abutment 24 or gap to make a longer pipe string 20.
The string elevator 23 grips the upper end 22a of the pipe segment,
now the new proximal end of the pipe string 20, and lifts the
lengthened pipe string 20 in the direction of arrow 27 to unload
the slips 18 of the spider 16 so that the slips 18 can move
upwardly and outwardly to disengage and release the lengthened pipe
string 20.
[0052] FIG. 7 is an elevation view of the pipe string 20 (now
including the pipe segment 22) after it has been lowered further
into the borehole 6 in the direction of the arrow 28. The
now-welded abutment 24' is shown below the level of the rig floor
14 and the spider 16 and within the borehole 6. The upper end of
the pipe segment 22, now the proximal end of the now-lengthened
pipe string 20, is positioned at a predetermined distance from the
rig floor 14 and above the spider 16 for being abutted or nearly
abutted to a new add-on pipe segment (not shown in FIG. 7) and then
welded using the friction stir welding machine (not shown in FIG.
7) to further lengthen the pipe string.
[0053] In another aspect, the friction stir welding machine 40 may
include a supply tube or hose within the power bundle 57 that
supplies a stream of an inert gas to supplant or dilute the air in
the immediate region of the FSW weld probe to decrease the
possibility of oxide forming on the weld as a result of the high
temperatures from friction between the probe and the workpieces.
Impurities, such as oxide formed during the FSW process, are
undesirable because they weaken the bond between the joined pipe
members. In one embodiment, the inert gas stream may be delivered
to the near-weld region through one or more ports formed in the
friction stir welding machine 40 adjacent to the stir probe 48.
[0054] After additional add-on pipe segments have been welded to
the pipe string and the desired length of the pipe string has been
achieved, the pipe string may be lowered into the borehole and then
radially expanded using an expander tool. Examples of expander
tools include cone-shaped mandrels such as that shown in FIG. 8 and
rotary expander tools such as the one shown in FIG. 9.
[0055] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *