Note: Descriptions are shown in the official language in which they were submitted.
CA 02261413 1999-02-11
TUBING INSERTION AND WITHDRAWAL APPARATUS
FOR USE WITH A LIVE WELL
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application Serial Number
60/037,140 filed February 14, 1997, hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to oil well equipment and services
related
thereto, and more particularly but not by way of limitation, to an apparatus
and method to
insert continuous lengths of small diameter tubing into a live oil well or the
like, and for
withdrawing the tubing therefrom.
2. Background
It is often advantageous to be able to install a continuous string of tubing
into an
oil well during development and production, as having such a tubing string
installed
provides the capability to pump certain types of fluid into the well for
various purposes,
such as for displacing undesirable fluids within the well, for stimulating
production of the
well and for cleaning and preventing corrosion of e,cpensive well components.
It is
preferable that the tubing be inserted while the well remains pressurized to
avoid the
inherent risk of well casing damage associated with shutting down the well.
Furthermore,
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1
it is desirable to use injection equipment and methods that minimize
disruption to routine
production activity.
The benefits of using inserted tubing, however, are accompanied with
potentially
expensive risks, and these must be minimized. A tube failure, such as tube
breakage,
kinking or corkscrewing, that occurs in the well can require recovery
procedures that can
be expensive and time consuming.
Attempts have been made to meet the needs of injecting and removing tubing in
the relatively rugged environment of a well site. A device generally known as
a coiled
tube injector receives continuous lengths of coiled tubing, and a gripping
mechanism
straightens and delivers the tubing to the well. When it is desirable to
remove the tubing
from the well, the coiled tube injector works in reverse to withdraw the
tubing from the
well and pay it back onto a reel for storage. With a coiled tubing injector
the same tubing
can be reused many times again.
An example of a coiled tube injector is described in U.S. Patent 4,585,061,
issued
to Lyons, Jr. et al., which illustrates a generally known approach of gripping
the tubing
and conveying it by a pair of opposed conveyors. The opposed conveyors provide
a tube
path through which the tubing is moved toward or away from the well bore,
depending on
the selected rotation of the conveyors.
Although improvements in the art have been made, many shortcomings of present-
day coiled tubing injectors are known. One major problem is that the coiled
tubing
inj ector cannot be positioned on or removed from a continuous length of
tubing without
cutting the tubing. Typically, a well servicing contractor inserts the tubing
to a specified
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well depth, and after cutting the tubing, removes the tube injector equipment
from the well
site. Cutting the tubing is limiting because the injected tubing obviously
cannot then be
used to inject fluids at a greater depth. Although welding the tubing after
cutting is
possible, such welding requires specialized skills and cumbersome cleaning and
purging
procedures. There is a need for an inj ector that would un-grip the tubing and
then could
be removed from a medial portion of the continuous tubing, leaving a
substantial length of
the tubing in place for use at the well site.
Another problem is that existing coiled tubing injectors are large and
cumbersome,
making it di~cult to reach many well sites. For example, the coiled tube
injector of U.S.
Patent 4, 585,061 mentioned hereinabove requires a tractor-trailer rig that is
di~cult if not
impossible to maneuver to many well sites. There is a need for a light weight,
self
contained unit that can be transported across di~cult terrain and through
narrow
passageways.
Still another problem is that existing coiled tubing injectors are limited to
use with
a single size of tubing. There is a need for a unit that accepts multiple
sizes of tubing to
accommodate different injection needs, depending on the flowrate and the
physical
properties of the fluid being injected.
The mechanical complexity of existing coiled tubing injectors is a major
problem.
The need to transfer a gripping force by the rotating conveyors that is
sufficient to support
and withdraw extremely long lengths of tubing has been met by complicated
transfer
assemblies made of many complicated and unique components. This results in an
expensive manufacture of the apparatus, as well as expensive maintenance and
repair for
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the operator.
There is a need for a low-cost design that simplifies the gripping action and
that
provides a reliable coil tubing injector requiring low-cost maintenance. These
problems
are resolved and other unrealized potentials in the art are gained by the
present invention.
SUIVIVIARY OF THE INVENTION
The present invention provides a coiled tubing injector for inserting and
withdrawing a continuous length of tubing into and out of a well. The coiled
tubing
injector has a tubing insertion and withdrawal assembly which includes a
tubing conveyor
assembly having a fixed conveyor and an opposing floating conveyor.
The conveyor chains of both conveyors support a plurality of gripper blocks
which
form a groove to engage the circumference of the tubing.
The floating conveyor can be moved away from the fixed conveyor to create a
gap
between the conveyors. A support frame is provided an opening which is aligned
with the
gap so that the tubing can be passed through the opening into the gap. This
allows the
tubing insertion and withdrawal assembly to be placed onto or removed from a
continuous
length of tubing without the need to cut the tubing.
A grip adjustment assembly draws the fixed and floating conveyors together to
close the gap and exert a gripping force on the tubing.
A conveyor stabilizing assembly provides stabilizing support to the conveyors.
The coiled tubing injector has a support stand assembly which clamps to a
hydraulic pack-off unit which is conventionally connected to the top portion
of a well
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head. The support stand assembly has clevis members that connect with clevis
members
of the tubing insertion and withdrawal assembly and is thereby hingedly
connected to the
support stand assembly. In this manner, the insertion and withdrawal assembly
is
supported by the support stand assembly and located therewith so that the
tubing is
linearly aligned with the hydraulic pack-off unit.
The support stand assembly provides a platform for a conventional load cell to
permit monitoring of reactive forces during insertion and withdrawal of
tubing.
An object of the present invention is to provide a coiled tubing injector
which can
insert a continuous tubing into a well bore and be removed therefrom without
severing the
IO tubing, and furthermore, a coiled tubing injector which can be reinstalled
to withdraw the
tubing without severing the tubing.
Another obj ect of the present invention, while achieving the above stated obj
ect, is
to provide a coiled tubing injector which can be maneuvered onto site
locations that are
difficult for prior art injectors to reach.
Another object of the present invention, while achieving the above stated
objects,
is to provide a coiled tubing injector which is economical to manufacture,
reliable in
operation and requires low-cost maintenance.
Other objects, advantages and features of the present invention will be
apparent
from the following description when read in conjunction with the accompanying
drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a coiled tubing injector constructed in accordance with the
present
invention.
FIG. 2A is a front elevational view of the tubing insertion and withdrawal
assembly of the coiled tubing injector of FIG. 1; FIG. 2B is a rear
elevational view of the
tubing insertion and withdrawal assembly.
FIG. 3 is a partial, front isometric view of the framework structure of the
tubing
insertion and withdrawal assembly of FIG. 2A.
FIG. 4 is an elevational view of one link of the conveyor chain and gripper
block
which are part of the conveyors in the tubing insertion and withdrawal
assembly of FIG.
2A.
FIG. 5 is a top view of the conveyor chain and gripper block of FIG. 4, also
showing the pressing engagement of the skate against the roller of the
conveyor chain and
the pressing engagement of the gripper block against the tubing.
1 S FIG. 6A is a rear elevational view of the skate positioned by the f xed
conveyor;
FIG. 6B is a side elevational view thereof; and FIG. 6C is a front elevational
view
thereof.
FIG. 7A is a front elevational view of the skate positioned by the moveable
conveyor; FIG. 7B is a side elevational view; and FIG. 7C is a rear
elevational view
thereof.
FIG. 8 is a front elevational view of the skates showing the grip adjustment
assembly and the conveyor stabilizing assembly.
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FIG. 9 is a top view of the grip adjustment assembly and the conveyor
stabilizing
system of FIG. 8.
FIG. 10 is an isometric view of the support stand assembly attached to a
hydraulic
pack-off of a well head, along with a stand-off clamp for supporting the
tubing after the
tubing insertion and withdrawal assembly of FIG. 2A is removed from the well,
leaving
the injected tubing in the well.
FIG. 11 is an elevational view of the stand-off clamp supporting the injected
tubing after the coiled tubing injector of FIG. 1 has been removed from the
well site.
FIG. 12 is an elevational view of the tubing decoiler of the coiled tubing
injector of
FIG. 1.
DESCRIPTION
Referring to the drawings in general, and more particularly to FIG. 1, shown
therein is a coiled tubing injector 10 constructed in accordance with a
preferred
embodiment of the present invention and injecting a tubing 11 into an oil well
12. The
coiled tubing injector 10 comprises a power unit 13, a control panel 14, a
tubing decoder
15, a tubing guide 16 and an articulating boom lift 17. Also, the coiled
tubing injector 10
comprises a tubing insertion and withdrawal assembly 18 which is positioned by
the
articulating boom lift 17 over the oil well 12. The coiled tubing injector 10
is supported
and transported by a mobile platform 19. It will be noted that the mobile
platform 19 of
FIG. 1 is a common tandem axle trailer, and as such the size and weight of the
coiled
tubing injector 10 of the present invention can easily be transported by a
personal vehicle
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such as a half ton pickup.
Referring now to FIGS. 2A and 2B, shown therein is the tubing insertion and
withdrawal assembly 18 which is comprised of the following major components: a
rigid
support frame 20 which substantially forms a box framework; a tubing conveyor
assembly
22 which is supported by the support frame 20; a grip adjustment assembly 24
which
interacts with the tubing conveyor assembly 22 to position the same for
gripping; a
conveyor stabilizing assembly 26; and a power assembly 28 supported by the
support
frame 20 to drive the tubing conveyor assembly 22.
The support frame 20, also shown in FIG. 3, has opposing horizontal members
30,
32 joined to opposing vertical members 34, 36 which together form a closed
framework
on the rear face of the support frame 20. FIG. 3 shows a left-hand face of the
support
frame 20, having a horizontal member 3 8 and a horizontal member 40 extending
from the
vertical member 36, and a vertical member 42 attached to the distal ends of
the horizontal
members 38, 40. A framework is formed on the right-hand face of the support
frame 20 in
a similar manner, as shown seen in FIG. 3 by the joining of horizontal members
44, 46 to
vertical member 34 and to a vertical member 48.
FIG. 2B is a view of the front face of the support frame 20. It will be noted
that
an opening 50 is formed in the front face of the support frame 20, for a
purpose to be
discussed hereinbelow. On one side of the opening 50, the support frame 20 has
a
horizontal member 54 and a horizontal member 56 extending from the vertical
member
42. A vertical member 58 is attached to the horizontal members ~4 and 56. In a
similar
manner, on the other side of the opening 50 the support frame 20 has a
horizontal member
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60 and a horizontal member 62, each extending from the vertical member 48 and
attached
to a vertical member 64.
FIG. 3 shows the bottom face of the support frame 20 has a rear support rail
66 and
a middle support rail 68, both attached to the horizontal member 40 and the
horizontal
member 44. A horizontal member 69 is attached to the middle support rail 68
and to the
horizontal member 56. A horizontal member 71 is attached to the middle support
rail 68
and to the horizontal member 62. It will be noted that the horizontal member
69, the
horizontal member 71, and a portion of the middle support rail 68 form an
opening 72 in
the bottom face of the support frame 20. Also, the opening 72 therein is
contiguous to,
and communicates with, the opening 50 formed in the front face of the support
frame 20.
FIG. 3 shows a front support rail within the bottom face of the support frame
20
extending from both sides of the opening 72, the front support rail having a
first member
74 disposed between the horizontal member 40 and the horizontal member 69, and
a
second member 76 disposed between the horizontal member 71 and the horizontal
member 44.
The support frame 20 shown in FIG.3 is of a conventional welded square tubing
construction, as is known to one skilled in the art. Various equivalent
embodiments are
contemplated and may be employed with regard to tube configuration, bracing,
gusseting
and the like. A novel feature of the support frame 20, in conjunction with
other features
and elements of the present invention to be described hereinbelow, is a
passageway 78,
formed by the opening 50 and the opening 72, which permits moving a medial
portion of a
continuous length of tubing 11 in a lateral direction as is indicated by arrow
81, so as to
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place the medial portion of the tubing 11 inside the support frame 20.
Returning now to FIGS. 2A and 2B, the tubing conveyor assembly 22 of the
tubing insertion and withdrawal assembly 18 has a laterally moveable conveyor
82, also
sometimes referred to herein as the floating conveyor 82, and an opposed fixed
conveyor
84. The floating conveyor 82 is slidingly supported by the support frame 20 so
that the
floating conveyor 82 can be separated from the fixed conveyor 84 which is
rigidly
supported by the support frame 20. A pair of guides (not shown) can be
provided on the
rear support rail 66 and the second member 76 to constrain the movement of the
floating
conveyor 82 in a conventional manner so as to provide lateral movement of the
floating
conveyor 82 relative to the fixed conveyor 84. It will be noted that a gap
between the
conveyors 82, 84, is formed when the floating conveyor 82 is moved away from
the fixed
conveyor 84. The gap is aligned with the passageway 78 so that a medial
portion of
tubing 11 can be moved through the passageway 78 to extend along the length of
the gap.
The floating conveyor 82 has an upstanding column support 86 supported at a
bottom end thereof by a base plate 88 which is slidingly supported by the rear
support rail
66 and the first member 74 of the support frame 20. The column support 86 is
constructed, as will become clear below, from a pair of angle-iron beams with
parallel
flanges that are spaced apart and joined by spreader plates.
A pair of bearings 92, 93 are attached to an upper portion of the column
support
86, and a pair of bearings 94, 95 are attached to a lower portion of the
column support 86.
The bearings 92, 93 support a shaft 96, which in turn supports a free-wheeling
sprocket
98. The bearings 94, 95 support a shaft 100 which, in turn, supports a driven
sprocket
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102.
The power assembly 28 has a motor baseplate l04 has a plurality of slotted
apertures (not shown) through which fasteners 105 are received for locking the
baseplate
l04 to the base plate 88. A motor l06 is supported by the motor baseplate 104,
the motor
l06 having a shaft l08 depending therefrom for imparting rotational motion to
a sprocket
110. The sprocket 11 Q is in mating alignment with a sprocket 102A which is
rigidly
connected to the sprocket 102, and a chain 112 is trained over the sprockets
110, 102A so
as to communicate rotational motion from the motor 106 to the driven sprocket
102.
Tension adjustment of the chain 112 is accomplished by loosening the fasteners
105 and
moving the motor l06 relative to the sprocket l02.
A conveyor chain 114 is trained over the driven sprocket 102 and the free-
wheeling sprocket 98, so that rotational motion from the motor 106 is
communicated to
the conveyor chain 114. The sprocket 98 is mounted to the column support 86 in
a
conventional manner so as to vary the distance between the sprockets 98 and
102 for the
purpose of proper chain tensioning. FIGS. 4 and 5 show a link 115 of the
conveyor chain
114, each link 115 having a pair of rollers 116 connected to a pair of
opposing links 118.
An opposing pair of link plates 120 are connected by fasteners 122 which
clearingly pass
through apertures (not shown) in the link plates 120 and through the center
bores of the
rollers 116. A conveyor chain well suited for the purposes of the present
invention as
described herein is that of a conveyor chain made by Diamond Chain of
Indianapolis,
Indiana, model number WCS2 (one hole).
As shown in FIGS. 2A and 2B, the column support 86 includes a horizontally
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disposed pin l24 , and the grip adjustment assembly 24 includes a skate l26.
FIG. 6B is a
side view of the skate 126 which forms a slot or notch l28 that receivingly
engages the
pin 124 to provide pivotal engagement therebetween. The conveyor chain 114,
trained
over sprockets 98, 102, also is trained over the skate 126 which serves to
press the
conveyor chain 114 in gripping engagement with the tubing 11 as discussed
further below.
Returning to FIGS. 2A and 2B, the opposing fixed conveyor 84, in similar
manner
to the conveyor 82, has a conveyor chain 130 trained over a free-wheeling
sprocket l32, a
driven sprocket 134, and a skate 136 that are all supported by a column
support 137. The
column support 137 is supported by a baseplate 137A a series of bolt receiving
openings,
and the support frame 20 has several upstanding bolts 137B extending from the
rear
support rail 66 and the first member 74 of the front support rail. When the
baseplate 137A
is placed on the support frame 20, the upstanding bolts 137B extend through
the receiving
openings and securing nuts (not shown) are provided to secure the baseplate
137A in
place.
A motor 138 rotates opposite to that of the motor 106 so that if the motor 106
is
rotating sprocket 102 in a clockwise direction as depicted by directional
arrow 140 in FIG.
2B, the motor 138 rotates sprocket 134 counter-clockwise, depicted by
directional arrow
142. The remaining structural details of the conveyor 84 are substantially
identical to that
described above for the conveyor 82, so the same structure designation numbers
are
provided in FIGS. 2A and 2B therefor. Further structural description therefore
will not be
provided herein.
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It should be noted that the skates 126 and 136 are supported independently
from
both of the floating conveyor 82 and fixed conveyor 84, constrained only by
the pins 124
which are engaged in the slots 128 and a similar slot 164 of the skates 126,
136,
respectively. This unique suspension achieves isolation of the elements which
provide the
gripping force to the tubing 11 from other forces, and the gripping force can
be repeated
with regularity without regard to the lateral positions of the conveyors 82,
84.
Returning to FIGS. 4 and 5, a gripper block 144 is supported between the link
plates 120 by a bolt fastener 14b. Preferably, the bolt fastener 146 has a
selected threaded
length such that, once tightened, it secures the link plates 120 in spaced
apart relationship
without pressingly engaging the gripper block 144. In this manner the gripper
block 144
is free to pivot about the bolt fastener 146. The pivotal support of the
gripper block 144
provides for automatic alignment with the tubing 11, thus maximizing the
gripping force
while minimizing damage. Preferably, the bolt fastener 146 has a locking nut
such as a
Nylock brand fastener to prevent loosening during operation. A plurality of
gripper
blocks 144 are supported by the conveyor chains 114, 130, and cooperate
therewith to grip
the tubing 1 I and provide a path for its linear displacement.
In FIG. 5 the gripper block l44 is pressingly engaging the tubing 11 (shown in
cross-section) along an arcuate groove I50, the radius of curvature of the
arcuate groove
150 being substantially the same as that of the tubing 11. Frequently it is
necessary to
insert or withdraw different sizes of tubing into a well. The gripper block
144 of the
present invention provides an alternate arcuate groove 152 which has a radius
of curvature
corresponding to a different size tubing. To change the size, the bolt
fastener l46 is
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removed, the gnipper block 144 is rotated 180 degrees, and the bolt fastener
146 is re-
installed. Also, the gripper block 144 in each of the links 11 S can be
replaced with gripper
blocks having selected sizes of grooves as may be necessary to accommodate any
size
tubing required for a specific location.
The conveyor chains 114, 130 and gripper blocks 144 of the conveyors 82, 84
cooperate to inject tubing 11 into or withdraw tubing 11 from a well. If, as
described
above and referring to FIG. 2B, the driven sprocket 102 is rotating in
direction 140 and the
driven sprocket l34 is rotating in direction 142, then the opposing conveyor
chains 114,
130 have elongated opposing portions supporting gripper blocks 144 that
contact the
tubing 11 and displace it upward, which is associated with withdrawing the
tubing from a
well. Reversing the direction of both motors, therefore, results in the
elongated opposing
portions of the conveyor chains 114, 130 cooperatively moving in a downward
direction,
which is associated with inserting the tubing 11 into a well.
An understanding of the gripping system which determines the force with which
the grippes blocks 144 engage the tubing 11 requires a preliminary
understanding of the
construction of the skates 126, 136. As noted above, FIGS. 6A, 6B, and 6C show
rear,
side and front elevational views, respectively, of the skate 126. The skate
l26 is a portion
of the grip adjustment assembly 24 and is positioned along the elongated
portion of the
conveyor chain 114 by the pin l24 of the column support 86. The skate 126 has
a central
body l 53 which forms the slot 128 and which supports a bearing plate 1 ~4
having a
bearing surface 15~, a pair of rear guides 156, and two pairs of front guides
1~7 (FIG. 6C),
one pair on each side of the body 1 ~3. Each rear guide 1 ~6 has a pair of
apertures 1 ~ 8
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(FIG. 6A) which are aligned with central bores l60 of the front guides l57
(FIG. 6C). In
the embodiment shown, the front guides 157 are made of conventional hexagonal
threaded
fasteners that have been drilled out to remove the internal threads and thus
form
substantially smooth central bores 160. The apertures 158 of the rear guides
156 likewise
are substantially smooth, non-threaded bores.
FIGS. 7A, 7B, and 7C show front, side and rear elevational views,
respectively, of
the skate 136. The skate 136, as a portion of the grip adjustment assembly 24,
is
positioned along the elongated portion of the conveyor chain 130 by the pin
l24 of the
column support 137. The skate 136 has a central body 162 which forms a slot
164 to
engage the horizontal pin l24 supported by the column support 137. The central
body 162
supports a bearing plate l66 having a bearing surface l68; a pair of rear
guides 170; and
two pairs of font guides 172 (FIG. 7A), one pair on each side of the central
body 162.
Also, the front guides 172 and the rear guides 170 have smooth bored apertures
174, 176,
respectively. Unlike the skate 126, the rear guides 170 each support a pair of
threaded
fasteners 178, the bores of which are coaxially aligned relative to the bored
apertures 176.
In an alternative embodiment, the threaded fasteners 178 can be omitted if the
apertures
176 of the rear guides are thread bearing.
Turning now to FIGS. 8 and 9, shown therein are the grip adjustment assembly
24
and the conveyor stabilizer assembly 26. The grip adjustment assembly 24 has a
pair of
threaded rods 180, each having two nuts 182 threadingly engaged thereon near a
proximate end and tightened against each other to form a hexagonal head which
facilitates
the taming of the rod 180 with a conventional wrench corresponding to the size
of the nuts
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CA 02261413 1999-02-11
182. Each of the rods 180 passes through the rear guide 156 and the front
guide 157 on
one side of the skate 126, as well as the front guide 172 and the threaded
fastener l78 on
one side of the skate 136. A spring 184 is compressed between the rear guide
156 and a
pair of set nuts 186 which are tightened against each other to lock in place
on the threaded
rod 180. FIGS. 8 and 9 show that a total of four such threaded rods 180 engage
the skates
126, 136, two on each_side, one above and one below the horizontal center. As
shown, the
pins 124, which are engaged by the slots 128 and 164 of the skates 126 and
136,
respectively, are supported on the column supports 86, 137 with each pin l24
supported
by a pair of coaxially aligned tubular collar supports 187. The tubular collar
supports 187
are attached to cross braces 188, and each of the cross braces 188 is in turn
attached to the
column supports 86, 137. Cotter pins 189 disposed through holes near the ends
of the pins
124 assure retention thereof in the collar supports 187.
Returning to FIG. 5, it will be noted that the bearing surface 1 SS of the
bearing
plate I 54 of skate 126 pressingly engages the roller 116 of the conveyor
chain 114.
Similarly, the bearing surface 168 of the bearing plate 166 of skate 136
pressingly engages
the rollers of the conveyor chain 130. As the force provided by the skates
126, 136,
against the conveyor chains 114, 130 increases, therefore, the force with
which the gripper
blocks l44 grip the tubing 11 is increased. From an understanding of the
previously
described drawings, it will further be noted that when the distal end of the
threaded rod
180 is threadingly engaged with the skate 13 6, turning the rod 180 in a first
direction
draws the skates 126, 136 toward each other and hence increases the gripping
force on the
gripper blocks 144. The skate 126 is influenced by the nuts 186 which compress
the
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CA 02261413 1999-02-11
spring 184 and, in turn, pressingly engage against the rear guide I56. The
skate I36 is
influenced in the opposite direction by the threaded engagement of the rod 180
in the
threaded fastener 178.
Another distinct advantage of the skate 126, 136 grip adjustment system of the
present invention is the ease with which the rods 180 can be removed in order
to pass
tubing 11 into the gap between the opposing gripper blocks 144. By rotating
the rods 180
on one side of this skates 126, 136 in a second rotational direction, the
gripping force is
lessened and eventually the distal ends of the rods 180 will disengage the
threaded
fasteners 178. Thereafter, the rods 180 can be pulled away from the skate 136,
because
the rod 180 slidingly engages the front guide 172 of the skate 136 and the
guides 157, 156
of the skate 126.
The conveyor stabilizer assembly 26 provides added strength and rigidity to
the
column supports 86, 137 during operation of the apparatus. In FIGS. 8 and 9
there are
shown several threaded rods 190. Each threaded rod 190 has a pair of nuts 192
tightened
I 5 against each other near a proximate end to provide a wrench hold of the
rod 190. The rod
190 slidingly passes through clearance apertures (not shown) in flanges l94,
196 of the
column supports 86, l37, respectively. A threaded member 198 is supported by
the flange
196 to threadingly receive a distal end of the rod l90. A spring 200 is
compressingly
disposed between the flange l94 and a pair of nuts 202 which, like nuts 192,
are tightened
against each other to lock them in place on the rod 190.
With the rod 190 threadingly engaging the threaded member 198 as shown,
corning
of the rod I90 in a first rotational direction, as with a wrench on the nuts
192, pulls the
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column supports 86, 137 together. The column support 86 is influenced by the
nuts 202
which compress the spring 200 and which in turn pressingly engages the flange
194. The
column support 137 is opposingly influenced by threading engagement of the rod
l90 in
the threaded member 198.
Four such conveyor threaded rods 190 are employed in the embodiment described,
two on each side of the skates 126, 136, one above and one below the
horizontal center.
In this manner, it will be noted that the conveyors 82, 84 are stabilized by
supporting the
column supports 86, 137. Like the previously described skate tensioner rods
180, the rods
190 are easily and quickly removed from the path of a tubing 11 string passing
into the
gap between gripper blocks 144. By turning the rod 190 in a second rotational
direction,
the distal end will disengage the threaded fastener 198. Thereafter, the rod
190 can be
pulled away from the column support 137 because the rod 190 slidingly engages
the
flange 194.
Yet another novel feature of the present invention is the manner in which the
tubing insertion and withdrawal assembly 18 is supported upon a well head
during
operation of the apparatus. FIG. 1 schematically shows a support stand
assembly 204
attached to the upstanding well head and supporting the tubing insertion and
withdrawal
assembly 18. The support frame 20 has a pair of clevis members 206, 208 which
depend
from the bottom horizontal member 32. Turning now to FIG. 10, the support
stand
assembly 204 is shown clamped to a hydraulic pack-off unit 210. In this manner
the
support stand assembly 204 in conjunction with the hydraulic pack-off unit 210
allows the
apparatus of the present invention to insert or withdraw tubing from a live,
pressurized
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CA 02261413 1999-02-11
well casing.
The support stand assembly 204 provides a two-piece support stand and has a
first
member 212 and a second member 2I4 that are joined together by a plurality of
fasteners
216. Each of the first and second members 212, 214 forms an arcuate portion
which,
when joined by fasteners 2l6, clamps the support stand assembly 204 to the
hydraulic
pack-off unit 210
The support stand assembly 204 has a pair of clevis members 218, 220 which are
spatially separated so as to flank the clevis members 206, 208 of the support
frame 20.
With all four clevis members 206, 208, 218, 220 aligned, a pin 222 is inserted
therethrough to secure the support frame 20 of the tubing insertion and
withdrawal
assembly 18 to the support stand assembly 204. The pin 222 has a handle
portion 224
which, when the pin 222 is fully inserted, passes into a locking channel
formed by a
locking tab 226 to retain the pin 222 in a locked position.
The support stand assembly 204 and the support frame 20 of the tubing
insertion
and withdrawal assembly 18 cooperate such that the pinned alignment of the
clevis
members 206, 208 with the clevis members 218, 220 places the tubing 11 pathway
created
by the opposing gripping blocks 144 in alignment with the central opening (not
shown) of
the hydraulic pack-off unit 210. The support stand assembly 204 furthermore
has a
platform 228 to support a conventional load cell (not shown). The support
frame 20 of the
tubing insertion and withdrawal assembly 18 is thus supported upon the load
cell so that
the weight of suspended tubing 11 can be monitored as it is inserted or
withdrawn to
anticipate difficulties associated with restrictions to a smooth insertion or
withdrawal of
N.\wptilesvpl5\_1963\Applicauon.wpd 1
CA 02261413 1999-02-11
the tubing 11 from the oil well 12.
A tube stand-off clamp 230 is constructed of a pair of angle-iron members with
a
groove (not shown) in the mating faces to receivingly engage the tubing 11.
The opposing
angle-iron members are joined by a plurality of fasteners 232. The fasteners
232 can be
loosened to allow the tubing 11 to slidingly pass while being inserted or
withdrawn from a
well. When the tubing 11 has been inserted to a desired depth, the fasteners
232 can be
tightened to grippingly retain the tubing 11 at the desired depth. With the
stand-off clamp
230 thus tightened and supporting the string of tubing 11 in the well, the
tubing insertion
and withdrawal assembly 18 can be removed from the tubing 11 if necessary. The
support
stand assembly 204 can also be removed from the hydraulic pack-off unit 210 by
removing the fasteners 216 to separate the members 212, 214. FIG. 11
illustrates a oil
well 12 head with the hydraulic pack-off unit 210 wherein the tubing insertion
and
withdrawal assembly 18 and the support stand assembly 204 of the present
invention have
been removed after the tubing 11 has been inserted.
Returning to FIG. 1, shown therein is the tubing guide 16 which is detachingly
supported by the tubing insertion and withdrawal assembly 18. The tubing guide
16 forms
an arcuate support for the coiled tubing during the transition from a coiled
roll and
delivers the tubing to the tubing insertion and withdrawal assembly 18 where
the tubing is
gripped by the conveyors 82, 84. A pair of opposing tube guides 234 (FIG.2A),
236 (FIG.
2B) are medially supported by the conveyors 82, 84 adjacent the tubing guide
16 and the
conveyor chains 114, 130 to urge the tubing 11 into the tubing path created by
the
opposing gripper blocks l44. Similarly, a pair of opposing tube guides 238
(FIG. 2A),
V ',wpfilesiDIS'~I963Upplication.wpd
CA 02261413 1999-02-11
240 (FIG. 2B) are similarly supported by the opposing conveyors 82, 84 at the
lower ends
thereof. Preferably, these guides have high-density composite wear surfaces,
such as
nylon, to prevent scarnng of the tubing 11 being injected into, or removed
from, the oil
well 12. The tube guides 234, 236 and 238, 240 may be pivotally supported by
one of the
conveyors 82, 84 to facilitate movement thereof to clear a path for a tubing
11 string that
is passing into the gap between the opposing gripper blocks 144.
As FIG. 1 shows, the tubing 11 is stored in a coiled roll on a spool 242 that
is
supported by a tubing decoiler assembly 15. FIG. 12 shows the tubing decoiler
assembly
15, wherein it will be noted that a cradle support frame 244 supports a shaft
(not shown)
which attaches to the spool 242 for rotation thereon. A fluid swivel 246 is
provided at one
end of the shaft to provide fluid communication between a supply line 247 and
the tubing
11 for the flow of desired fluids into the oil well 12 through an injected
string of tubing
11. The shaft is controllably rotated by a hydraulic motor 248 and an
interconnecting
chain 250. The motor 248 is used to impart a braking force to the spool 242
during
1 ~ lowering of the tubing 11, in order to provide tension on the tubing 11 to
aid in
straightening it as it traverses the tubing guide 16, and furthermore to
prevent backlash
uncoiling of the spool 242. The motor 248 is also used in the reverse
direction to wind the
tubing 11 back onto the spool 242 when the tubing 11 is withdrawn from the
well.
A hydraulic pressure line 252 delivers pressurized hydraulic fluid from a
reservoir
(not shown) to the tubing decoiler assembly 15. A metering valve 254 provides
a speed
control for the motor 248 during such times that it is used to wind the tubing
11 back onto
the spool 242 as the tubing 11 is withdrawn from the oil well 12. A pressure
control valve
V ~,wpfila~DIS12I963V1pplicauon.wpd 21
CA 02261413 1999-02-11
~.
i.:
256 regulates the pressure exerted on the tubing 11 as it is being withdrawn.
A solenoid
valve 258 is used to switch the motor 248 between a first mode wherein it
provides a
brake on the tubing 11 as it is decoded, and a second mode wherein it provides
the power
to wind the tubing 11 back onto the spool 242.
In the first mode, the solenoid valve 2S8 is not energized, resulting in a
blockage
of pressurized fluid in line 252 past the solenoid valve 258. In the
unenergized state a
flow path exists from the reservoir to the motor 248 by line 260, and out of
the motor 248
back to the reservoir by line 262 and line 264. In this mode the motor 248
acts as a
hydraulic pump between suction line 260 and return line 264. A metering valve
266 on
the return line 264 allows a variable back pressure so as to control the
tension on the
tubing 11 as it is decoiled from the spool 242.
In the second mode, the solenoid valve 258 is energized, resulting in a flow
of
pressurized fluid from line 2S2 to line 262 and into the hydraulic motor 248.
The fluid
returns to the reservoir in line 260. In this mode the motor 248 operates with
a selected
constant pressure as determined by the pressure control valve 256 and a
selected speed as
determined by the speed control valve 254.
Finally, FIG. 1 shows an articulating boom lift assembly 17 is provided to
place
the tubing insertion and withdrawal assembly 18 into a working position on the
support
stand assembly 204 as described above, and also to load and unload spools 242
of tubing
onto the tubing decoder 15. A pair of horizontal lift members 268, 270 (FIG.
3) on the
rear face of the support frame 20 of the tubing insertion and withdrawal
assembly 18 are
provided to support stabilizing bars 272, 274 which are opposingly supported
by the
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CA 02261413 1999-02-11
mobile platform 19.
It is clear that the present invention is well adapted to carry out the
objects and to
attain the ends and advantages mentioned as well as those inherent therein.
While
presently preferred embodiments of the invention have been described in
varying detail
for purposes of the disclosure, it will be understood that numerous changes
may be made
which will readily suggest themselves to those skilled in the art and which
are
encompassed within the spirit of the invention disclosed and as defined in the
above text
and in the accompanying drawings.
Nlwpfila\Dls'C1963Uppliauon.wpd 23
