Note: Descriptions are shown in the official language in which they were submitted.
CA 02638731 2008-08-13
HYDRAULIC RUNNING TOOL ASSEMBLY AND METHOD OF.ITS USE
TECHNICAL FIELD OF THE INVENTION
The present invention relates to running tools for drilling and completion
operations. In
particular, the present invention relates to an obstructed bore hydraulic
running tool with optional
mechanical activation.
BACKGROUND OF THE INVENTION
It is known to provide running tools, including obstructed bore running tools
for drilling
operations. Such running tools often include slips, dogs, or latches that
restrict axial movement
during deployment, but are prone to slippage or dragging, which may cause
damage to the
interior bore of the casing. Prior art running tools are also prone to
premature release, increasing
deployment time thereby reducing deployment efficiency.
It is desirable to provide a running tool assembly which does not employ
slips, dogs or latches,
and does not suffer from premature release. The present invention meets these
objectives.
SUMMARY OF THE INVENTION
There is provided an assembly for downhole equipment deployment, comprising a
liner hanger
having a wall and a bore, a plurality of pin holes through the wall
equidistant from the uphole
end of the liner hanger, and means for attachment of the downhole end of the
liner hanger to the
uphole end of deployable equipment; a top sub having a wall, a throat section
at its downhole
end and a plurality of pin holes through the wall in the throat section, the
pin holes alignable with
the corresponding pin holes of-the liner hanger, the downhole end of the top
sub insertable into
the uphole end of the liner hanger, and the uphole end of the top sub
attachable to the downhole
end of a string by top sub string attachment means; a lock piston having at
its downhole end a
plurality of collet fingers with a slot defined between each pair of adjacent
collet fingers, the
downhole end* of each slot having a pin entrance with a first width greater
than the width of the
remainder of the slot, each of the pin entrances alignable with corresponding
pin holes of the top
sub and liner hanger, the lock piston insertable into the throat section of
the top sub with the
collet fingers oriented downhole, wherein the circumference of the lock piston
at the position of
the pin entrances is greater than its circumference at the position of the
uphole end of the slot; a
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plurality of lock pins, insertable through the pin holes of the top sub, the
pin holes. of the liner
hanger, and the pin entrances of the slots of the lock piston; means for
releasably connecting the
top sub and the lock piston; and means for remotely releasing the liner hanger
from the top sub
and the lock piston.
The means for releasably connecting the top sub and the lock piston may
comprise a plurality of
screw holes through the outer wall of the liner hanger, a plurality of
corresponding screw holes
in the outer surface of the lock piston, and a plurality of shearable screws
insertable through the
screw holes of the top sub into the screw holes of the lock piston.
The shearable screws may be manufactured of brass. The diameter of the bore
may be between
4.068 inches and 7.983 inches, in a casing having characteristics of 4 1/20 X
9.50 lbf/ft thru 9
5/80 X 75.60 lbf/ft. Preferably, the diameter of the bore may be between 4.535
inches and 6.337
inches in a casing having characteristics of 5.00 X 11.50 lbf/ft thru 7 5/80 X
47.10 lbf/ft.
The plurality of pin holes in the liner hanger and the top sub may comprise
four pin holes.
The means for attachment of the downhole end of the liner hanger to the uphole
end of
deployable equipment may be any attachment means, including a threaded male
(pin) connection
means. The top sub string attachment means may comprise any attachment means,
including a
threaded female (box) connection means.
The plurality of collet fingers may comprise four collet fingers.. The
downhole ends of the collet
fingers of the lock piston may join to form an annular downhole lock piston
terminus.
The means for remotely releasing the liner hanger from the top sub and the
lock piston may
comprise mechanical means. ' The mechanical means for remotely releasing the
liner hanger from
the top sub and the -lock piston may comprise a mechanical activation
component disposed
between the uphole end of the top sub and the downhole end of the str'ing, the
mechanical
activation component threadably insertable into the top sub to effect release
of the lock piston
from the top sub. The means for remotely releasing the liner hanger from the
top sub and the
lock piston may instead comprise hydraulic means.
The top sub may further comprise at least one hydraulic fluid drain disposed
in a position which
is downhole of the uphole end of the lock piston when the lock piston is in a
pre=activation
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position, and uphole of the uphole end of the lock piston when the lock piston
is substantially in
an activated position;'the hydraulic activation means may comprise an
activation ball disposable
into the hole to a position in proximity to the uphole end of the lock piston;
and a supply of
pressurized hydraulic fluid for seating the ball in the mouth of the lock
piston.
There is further provided a method of operating a running tool assembly for
deploying downhole
equipment from the surface, comprising the following steps: assembling'a liner
hanger, top sub,
lock piston, lock pins, shear screws and seals into a running tool assembly;
attaching the
assembly to a tubing string; inserting the assembly into a selected hole to a
desired depth;
dropping an activation ball downhole; pumping hydraulic fluid from the surface
to seat the ball,
increase annulus string pressure, shear screws holding the lock piston to the
top sub, drive the
lock piston into the liner hanger, and retract the lock pins holding the liner
hanger to the top sub;
retrieving the assembly apart from the liner hanger by pulling the tubing
string out of the hole.
The method of operating a running tool assembly may further comprise the
additional final step
of refitting the assembly.
A method of operating a running tool assembly for deploying downhole equipment
from the
surface, may comprise the following steps: assembling a liner hanger, top sub,
lock piston, lock
pins, shear screws and seals into a running tool assembly; attaching the
assembly to a tubing
string; inserting the assembly into a selected hole to a desired depth;
rotating the string to
mechanically shear screws holding the lock piston to the top sub, drive the
lock piston into the
liner hanger, and retract the lock pins holding the liner hanger to the top
sub; retrieving the
assembly apart from the liner hanger by pulling the tubing string out of the
hole. The hydraulic
fluid may be in a gas phase.
There is also provided use of the assembly as described downhole deployment of
equipment.
The downhole deployment of equipment may be in any industry, not limited to
oil and gas
drilling and completion.
One advantage of the present invention is in the use of obstructed bore
technology to restrict
potentially hazardous downhole debris from entering the lower portion of the
string, thereby
avoiding potentially damage to the seating area of the tool.
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Another advantage of the present invention is the ability to activate the
tooling in either a state of
compression or tension of the string.
Another advantage of the present. invention is the choice of deployment method
between
hydraulic activation and mechanical activation, the latter providing a back-up
system for
downhole equipment release should hydraulic activation not be an option.
Other advantages of the present invention include the ease of field dressing
for return to service,
and simple maintenance requirements.
A further advantage of the present invention is the retrievability of the
entire assembly except for
the liner hanger, also known as a liner hanger, leaving a minimum of steel
downhole.
BRIEF DESCRIPTION OF THE INVENTION
A detailed description of the preferred embodiments'is provided by way of
example only and
with reference to the following drawings, in which:
Fig. 1 is a perspective view of a top sub of the assembly, according to the
invention;
Fig. 2 is a cross-sectional view of a top sub of the assembly, according to
the invention;
and
Fig. 3 is a perspective view of a lock piston of the assembly, according to
the invention;
Fig. 4 is a cross-sectional view of a lock piston of the assembly, according
to the
invention;
Fig. 5 is a perspective view of a liner hanger of the assembly, according to
the invention;
Fig. 6 is a cross-sectional view of a liner hanger of the assembly, according
to the
invention;
Fig. 7 is a perspective view of a lock pin of the assembly, according to the
invention;
Fig. 8 is a longitudinal cross-sectional view of the assembly of the
invention, in a pre-
activation position;
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Fig. 9 is a lorigitudinal cross-sectional view of the assembly o the
invention, in an
activated position;
Fig. 10 is a transverse cross-sectional view of the locking pin mechanism of
the invention
in a pre-activated position;
Fig. 11 is a transverse cross-sectional view of the locking pin mechanism.of
the invention
in an activated positibn;
Fig. 12 is a cross-sectional view of a mechanical activation joint of an
alternate
embodiment of the assembly of the invention;
Fig. 13 is a cross-sectional view of the assembly of an alternate embodiment
of the
assembly of the invention depicting a mechanical activation joint, in a pre-
activated
position; and
Fig. 14 is a cross-sectional view of the assembly of an alternate embodiment
of the
assembly of the invention depicting a mechanical activation joint in an-
activated position.
In the drawings, one embodiment of the invention is illustrated by way of
example. It is to be
expressly understood that the description and drawings are only for the
purpose of illustration
and as an aid to understanding, which are not intended as a definition of the
limits of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
According to one embodiment of the present invention, there is provided a
tubular obstructed
bore assembly used for downhole equipment deployment in the oil & gas
industry. The
assembly is designed to be run into an equipment deployment target zone on a
tubing string. The
assembly may be activated hydraulically by a ball drop, or mechanically by
left-hand string
rotation. Activation may be accomplished while the string is in tension or
compression. The
assembly is substantially retrievable, and may be quickly field dressed for
return to service.
The assembly, according to one embodiment of the present invention, comprises
several
components, including a top sub, a lock piston, a liner hanger, lock pins,
shear screws, and seals.
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As depicted in Figs. 1 and 2, the top sub 2 is a cylindrical component having
a longitudinal bore
4 of varying diameter. A throat 6 at the uphole end of the top sub has the
widest bore. The top
sub has several sets of lateral holes perpendicular to the longitudinal bore
passing through the
wall of the top sub. A first set of lateral holes, hydraulic fluid drain holes
8, is situated at
position along the top sub uphole of the uppermost end of the lock piston when
the lock piston is
in an activated position. A second set of lateral holes, threaded screw holes
10, is situated at a
medial position along the top sub downhole of the drain holes. A third set of
lateral holes, lock
pin holes 12, is situated at a medial position downhole of the screw holes.
The top sub further
comprises an external channel 14 for receiving a pliable annular seal for
sealing the joint
between the top sub and the liner hanger.
As depicted in Figs. 3 and 4, the lock piston 16 has, according to one
embodiment of the present
invention, biased towards the uphole end of the lock piston, a plurality of
counterbore holes 18
corresponding to the threaded holes of the top sub. Extending from a medial
position of the lock
piston to the downhole end of the lock piston there are a plurality of collet
fingers 20 defining a
plurality of slots 22 between the collet fingers. In a preferred embodiment,
the downhole ends of
the collet fingers are joined to form an annular terminus 24. The closed slot
design of the lock
piston is preferred as the closed slot design is effective in preventing the
reverse motion of the
lock piston and possible blow back under conditions of high formation
pressure. In addition, the
closed slots provide increased strength to the collet fingers. In an alternate
embodiment, the
collet fingers may be independent at the downhole terminus.
A pin entrance 26 at the downhole end of each slot has a width sufficient to
receive the head of a
lock pin. The remainder of each slot extending longitudinally from the pin
entrance has a width
less than the width of a lock pin head greater than the width of a lock pin
neck, and less than the
width of a lock pin shoulder. The downhole end 28 of the lock piston has a
diameter
substantially equal to the uphole end of the lock piston. A medial section of
the lock piston
where the collet fingers extend begin has a narrower diameter. From the pin
entrance, the lock
piston diameter decreases towards the uphole end of the collet fingers.
As depicted in Figs. 5 and 6, the liner hanger 30 comprises a cylindrical
component having a
wall, a plurality of pin holes 32 proximal to the uphole end 34 of the liner
hanger, and means for
attachment of the liner hanger to deployable equipment at its downhole end.
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As depicted in Fig. 7, the lock pin 36 has a head 38 tapering from a first end
40 of the lock pin to
a first pin diameter, the head adjacent a neck 42 having a second pin
diameter, and the neck
adjacent a shoulder 44 having a third'pin diameter. The first pin diameter is
less than the width
of the pin entrance of each slot and greater than the width of the remainder
of each slot. The
second pin diameter is less than the width of the remainder of each slot, the
third pin diameter is
greater than the width of the remainder of the slot and greater than the width
of the pin entrance.
The tapered head allows the lock pin to enter the pin entrance of the lock
piston. The narrower
neck may slide freely within the slot, and remains engaged by the wider head
and shoulder of the
pin.
As depicted in Fig. 8, the assembly according to one embodiment of the present
invention
includes a top sub 2, a lock piston 16 having a downhole end releasably
insertable in the throat of
the top sub, a liner hanger 30 for receiving in an uphole end the downhole end
of the top sub. In
a pre-deployment arrangement, the lock piston may be secured in position
within the top sub by
shearable screws.
With further reference to Fig. 8, a first phase in operation of the present
invention is assembly of
the running tool. A top sub may be supplied with a soft seal o-ring 46 and may
be inserted
through the uphole bore of the liner hanger. The top sub may be supplied with
internal soft seals
48. The pin holes of the liner hanger may be aligned with the pin holes of the
top sub. The lock
piston may be inserted into the throat of the top sub with the collet fingers
in a downhole
orientation. The lock piston may be rotated to align the slots with the holes
of the liner hanger
and the top sub.
Soft seals may be assembled onto the lock pin. The lock pins =may be insertcd
through the
aligned pin holes in the top sub and the liner hanger. In the preferred
embodiment having a
closed slot design, the lock piston may be positioned with the pin entrance of
each slot aligned
with a corresponding pin hole of the liner hanger. The lock piston may be
pushed further down
the throat of the top sub to align the counterbore holes at the uphole end of
the lock piston with
the threaded holes of the top sub. Brass shear screws 50 may be inserted. The
liner hanger may
be connected and screwed onto the tubing string.
In operation, the assembly is deployed on a tubing string to a desired depth.
In the preferred
method of activation, deployment of the assembly may be effected hydraulically
using annular
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string fluid. In a preferred embodiment, the fluid is a liquid, preferably
water or a light weight
mud. In an alternate embodiment, the hydraulic fluid may be a non-liquid
fluid.
First, an activation ball 54 is dropped into the well into proximity with the
uphole end of the lock
piston. Next, hydraulic fluid from the surface is pumped into the string to
seat the ball in the
neck 56 of the lock piston. Once the ball is seated, the flow of fluid is
blocked, leading to an
increase in annulus string pressure to approximately 1005 psig. This hydraulic
force causes the
shearing of the brass shear screws holding the lock piston in position in the
top sub, releasing the
lock piston into the top sub.
Lock pins 36 are positioned in a retracted position around the circumference
of the top sub. The
downhole movement of the lock piston relative to the top sub and liner hanger
will cause the
lock pins to slide along the slots in the lock piston. The lock pins are
spring mounted to move
inwardly as the opening in the lock piston moves past the lock pin. Once the
pin head is through
the opening, the lock pin may not be retracted, as the lock piston has a neck
which is narrower
than the pin head and the slot, causing the lock pin to be guided along the
slot while the lock
piston circumference narrows. The narrowing inner circumference of the collet
fingers defining
the slots will draw the lock pins inwardly from the Iiner hanger until the
innermost ends of the
lock pins meet, forming an obstructed bore. The obstructed bore serves to
prevent upward flow
of debris which could unseat the activation ball. This could reduce hydraulic
fluid pressure and
prevent tool deployment.
As the pressure of the fluid drives the lock piston deeper into the top sub,
the lock piston
approaches a narrowed shoulder position in the top sub. In this `no-go'
position, the uphole end
of the lock piston is downhole of the fluid drain holes, permitting the
pressurized fluid to drain.
The momentum of the lock piston will carry it to the no-go shoulder position
in the downhole
end of the top sub.
Once the lock pins are retracted, the entire assembly, apart from the liner
hanger, may be
retracted from the hole. Once the tooling is released downhole, the assembly,
including the
activation ball, is retrieved by pulling the tubing string. The assembly may
be quickly inspected,
cleaned, redressed and returned to immediate operation if desired. Redressing
requirements are
usually only one soft seal and four brass shear screws. In the worst case,
four elastomers, four
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brass shear screws and a new activation ball may be required. Only the liner
hanger remains
with the deployed equipment, minimizing the amount of steel left downhole.
The size of the running tool may vary. The running tool may have a bore
corresponding to
industry standard bore sizes, for example, 41/2 inches, 5%z inches, 6 sis
inches, 7 inches or 9 5/8
inches. Other bore sizes are also contemplated to be within the scope of the
present invention.
In circumstances where hydraulic fluid is not available, or if hydraulic
activation faiIs, the
operator may decide to deploy the apparatus manually using mechanical means.
In an alternate
embodiment of the assembly for mechanical activation, the assembly may further
comprise, a
mechanical activation joint which may be placed between the tubing string and
the hydraulic
running tool. As depicted in Figs. 12-14, the mechanical activation joint
comprises a threaded
sleeve 58 engageable with the uphole end of the lock piston 16 and in
threadable relationship
with the inner circumference of the top sub 2. Counterclockwise rotation of
the sleeve draws the
sleeve in a downhole direction, mechanically forcing the lock piston downhole,
thereby shearing
the shear screws and passing the slots along the lock pins to retract the lock
pins from the liner
hanger.
If the assembly is activated mechanically, by operator choice or if the
hydraulic deployment
fails, the string may be rotated approximately 19 turns counterclockwise,
which drives the
threaded mandrel into the throat of the top sub, pushing down on the lock
piston to move it
downhole in the same manner as is affected by hydraulic fluid activation. With
the lock piston
shifted, the lock pins are retracted from the liner hanger, the tooling is
released and the string
may be retrieved.
The assembly may be run into a well, understood to be a hole drilled into the
earth's surface for
the purpose of extraction of composite hydrocarbon petroleum products. The
orientation of the
well into which the assembly may be run may be substantially vertical,
substantially horizontal,
or at a deviated angle between substantially vertical and substantially
horizontal. The well may
be linear or non-linear.
The present invention provides an efficient means, of downhole equipment
deployment without
use of interference devices that impart gripping to the interior bore of the
casing/liner. Prior art
devices such as slips, dogs and latches introduce frictional interference
which assist in preventing
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axial movement during deployment but are prone to slippage or dragging along
the interior bore
of the casing, which may cause damage to the casing. In contrast, the present
invention makes
use of pins which move radially in the well bore, operating perpendicularly to
the bore, rather
than parallel.
The capacity to deploy the assembly hydraulically or mechanically provides a
backup method if
hydraulic activation is not possible, thereby reducing the number of missed
runs with this
assembly. The assembly may be adapted for connection to any equipment meeting
industry
standards. The assembly of the present invention may be employed in any
drilling or completion
enterprise, not necessarily limited to oil and gas applications.
It will be appreciated by those skilled in the art that other variations of
the preferred embodiment =
may also be practised without departing from the scope of the invention.
