Note: Descriptions are shown in the official language in which they were submitted.
CA 02326268 2000-11-17
APPARATUS FOR AXIALLY DISPLACING A DOi~~NHOI~E TOOL
OR A TUBING STRING IN A WELL BORE
RELATED APPLICATIONS
This application is related to copending
Canadian patent application No. 2,223,214 filed on
27 November 1997 and entitled APPARATUS FOR AXIALLY
DISPLACING A DOWNHOLE TOOL OR A TUBING STRING IN A WELL
BORE.
TECHNICAL FIELD
This invention relates to the handling of
downhole well tools and tubing strings, and in particular
to an apparatus for axially displacing a downhole well
tool or tubing string in a well bore equipped with a
wellhead, the downhole well tool being supported by a
tubing string in the well which includes a telescoping
joint to permit the axial displacement of the downhole
well tool and the tubing string. As well as any downhole
operation in which well tubulars or downhole equipment is
manipulated or downhole operations are performed in which
pressure containment is necessary.
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CA 02326268 2000-11-17
BACKGROUND OF THE INVENTION
Downhole operations and the handling of
downhole well tools in completed wells has always
presented a certain challenge, especially when working in
wells having a natural pressure that exceeds atmospheric
pressure, necessitating the containment of the well at
all times. A further challenge has been the maintenance
of well bores which pass through production zones that
are not well suited to continuous production. For
example, a production zone which yields both water and
oil or gas or any combination thereof may require
relatively frequent repositioning of a lower end of a
production tubing in order to recover oil or gas
efficiently. Production zones which produce crude oil
high in waxy compounds or asphaltines, or laden with
salts, which tend to plug casing perforations and
therefore require frequent treatment to maintain an
economic flow of hydrocarbon are further examples of such
production zones.
To date, the maintenance of such wells has
proven time-consuming and expensive. For example, in
wells which produce both oil, water and gas and/or water
and gas and have a mobile water/hydrocarbon interface,
the production of hydrocarbon gradually decreases over
time until only water or gas is produced from the well.
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CA 02326268 2004-03-24
Relocation of the bottom end of the production tubing
string is then required to recommence oil production.
The relocation of the tubing string has been a complex
process which involved many time-consuming and expensive
steps that are well known in the art. It is not
difficult to appreciate that there is a need for a more
efficient and less costly system for producing oil or gas
from such wells. Such a system is described in
applicant's copending patent application referred to
above. The apparatus described in that patent
application eliminates many of the shortcomings of prior
art procedures for selectively producing fluids from
wells, performing barefoot completions of well bores in
sensitive zones, and other downhole operations using
production tubing and tools that require axial
displacement within a limited range in a well bore. At
the time of filing that patent application, it was
considered that the apparatus described in United States
Patent 4,867,243 which issued on September 19, 1989 to
Garner et al. would be suitable for effecting the axial
displacement of the downhole well tools. It has now been
recognized that such prior art tools for inserting
mandrels through wellheads is not necessarily adequate or
optimal for performing the axial displacement of such
downhole well tools.
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CA 02326268 2000-11-17
There are several reasons why such prior art
tools are not optimal tools for this purpose. First,
they are designed for inserting wellhead isolation
mandrels into wellheads and withdrawing them from the
wellheads after the well is serviced. Since wellhead
isolation mandrels are of inconsequential weight, they
are stroked through a wellhead relatively easily. Moving
a tubing string of 4,500' (1,500 metres), which is not
uncommonly encountered in handling downhole' well tools,
may require a force in excess of 50 tons. The force
required is due not only to the considerable weight to be
lifted but also to the extra force required to unseat
anchors and/or packers supporting the tubing string.
Such forces may subject the wellhead to potentially
damaging stresses. Second, wellhead isolation tools
provide no mechanism for rotating a downhole tubing
string since rotation is not required for the insertion
or withdrawal of a wellhead isolation mandrel.. When
manipulating a downhole tubing string, however,
rotational movement is often required in order to release
or set components such as packers, anchors, hangers and
the like. Considerable rotational force may be required
to accomplish the release of such components and it is
therefore desirable to provide a mechanism for
selectively rotating the downhole string as required.
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CA 02326268 2000-11-17
It has also now been recognized that certain
downhole operations can be more economically performed
through the wellhead with pressure containment than
performing those operations using a rig, for example. It
is also known that certain near-surface operations such
as the drilling out of permanent bridge plugs, cement
plugs or any other obstruction in the casing column
during re-entries require pressure containment in order
to avoid the escape of hydrocarbons to atmosphere and
potentially dangerous releases of contained pressure.
There therefore exists a need for an apparatus which is
adapted to provide pressure containment while enabling
downhole manipulations to move production tubing, and
remove near-surface obstructions with or without the use
of a telescoping joint in a tubing string.
SL1~ARY OF THE INVENTION
It is an object of the invention to provide an
apparatus for axially displacing a downhole tool or
tubing string in a well bore equipped with a wellhead
which is robust enough to permit a lengthy tubing string
to be displaced in the well bore.
It is a further object of the invention to
provide an apparatus for axially displacing a downhole
tool or tubing string in a well bore equipped with a
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CA 02326268 2000-11-17
wellhead which permits a tubing string alone or a tubing
string supporting the downhole tool to be rotated, if
required.
It is yet a further object of the invention to
provide an apparatus for axially displacing a downhole
tool or tubing string in a well bore equipped with a
wellhead which is stabilized to reduce stress on the
wellhead.
It is yet a further object of the invention to
provide an apparatus for axially displacing a downhole
tool or tubing string in a well bore equipped with a
wellhead which is safe to use.
It is also an object of the invention to
provide an apparatus for axially displacing,a downhole
tool or tubing string in a well bore equipped with a
wellhead which is readily transported from one well bore
to another.
It is a further object of the invention to
provide an apparatus for performing downhole operations
which require pressure containment at the wellhead.
These and other objects of the invention are
realized in an apparatus for axially displacing a
downhole tool or tubing string in a well bore equipped
with a wellhead, the downhole tool being supported by a
tubing string in the well which includes a telescoping
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CA 02326268 2004-03-24
joint to permit the axial displacement of the tool,
comprising:
a lift rod string;
a tool entry spool adapted to be mounted to a top of
the wellhead;
at least one annular seal for containing well
pressure mounted above the tool entry spool, the annular
seal providing a fluid seal around a periphery of the
lift rod string;
means for axially displacing the lift rod string;
means for selectively rotating the lift rod string;
and
a swivel joint for enabling free rotational movement
in a link rod between the means for axially displacing
the lift rod string and the means for selectively
rotating the lift rod string.
The apparatus in accordance with the invention
includes a lift rod string which is equipped with a
releasable latch tool for connecting a free end of the
lift rod string to a latch point in or near a telescoping
joint described in applicant's above-identified copending
patent application, or connected directly to a tubing
string. The lift rod string is supported on its top end
by a stem which is connected to the means for selectively
rotating the lift rod string. The means for selectively
DOCSOTT: 225668\1
CA 02326268 2004-03-24
rotating the lift rod string is preferably a motor. A
hydraulic or an electric motor or a mechanical rotational
device can be used. Attached to the stem for supporting
the lift rod string is a link rod that includes a swivel
joint for enabling free rotational movement between the
stem for supporting the lift rod string and the means for
axially displacing the lift rod string. The means for
axially displacing the lift rod string is preferably a
hydraulic cylinder or a mechanical jack, but any other
hoisting mechanism may be used.
In preferred embodiments of the apparatus
designed for use on deep wells, the apparatus is
supported and stabilized by adjustably extendible support
posts designed to rest on a ground surface surrounding
the wellhead. The support posts help bear the weight of
heavy tubing strings and stabilize the apparatus to
reduce torsional stress on the wellhead.
The apparatus preferably includes a tool entry
spool adapted to be mounted to a top of the wellhead.
The tool entry spool provides a space for accommodating a
latch tool such as a spear, key, collet, slip or friction
type tool, attached to the bottom end of the lift rod
string. Mounted above the tool entry spool is at least
one annular seal for containment of well pressure. The
annular seal may be a stuffing box, but it is preferably
_ g _
DOCSOTT: 225668\1
CA 02326268 2000-11-17
one or more blowout preventers. Desirably, a spool which
includes at least one tool window is provided above the
blowout preventer. The tool window provides access to
the lift rod string with gripping or locking devices
useful for inhibiting axial or rotational movement while
lift rod joints are being inserted or removed.
Alternatively, a pair of oppositely oriented well slip
assemblies such as described in United States
Patent 3,846,877 which issued on November 12, 1974 to
Spiri can be used in place of the tool access spool to
selectively inhibit axial or rotational movement of the
lift rod string.
Each joint of the lift rod string may include
axial bores which permit fluid to be circulated or pumped
straight through the lift rod string, if required. For
example, conditions are sometimes encountered in wells
such as gas wells where hydrating frequently occurs at or
near the well surface. Such hydrates can prevent entry
or retrieval, or foul or seize latch tools such as
spears, keys, collets, slips type or friction type tools
and prevent their release or proper functioning. If the
lift rod string includes axial bores to permit the
circulation of hot fluid, the string can be heated to
melt ice or paraffins, etc. and free up the seized
component to effect the desired release. One way of
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CA 02326268 2000-11-17
circulating fluid through the lift rod string is to use
aligned bores that extend through the means for axially
displacing the lift rod string so that a fluid connection
can be made at the top of the apparatus. If a hydraulic
cylinder is used for axially displacing the lift rod
string, the hydraulic cylinder is provided with a
polished rod that extends through a top of the cylinder.
A free end of the polished rod is equipped with threaded
connectors for the attachment of fluid circulation hoses
which are in turn connected to a pump and a heated
reservoir. It may also be desirable to pump fluid
straight through a lift rod string. This can be
advantageous for clearing hydrates or paraffin buildup
from a production tubing. One way of accomplishing this
is by modifying the spear, collet, slip or friction type
tool to let fluid flow out a bottom end of the lift rod
string, or to run in the lift rod string without a tool
on its bottom end so that fluid can be pumped through one
or both axial bores.
The apparatus in accordance with the invention
may also be used to axially or rotationally displace
tubulars in a well bore that are not equipped with
telescoping joints. If slip or spear latch tools, for
example, are used, a production tubing, or the like, can
be repositioned in a well without killing the well or
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CA 02326268 2000-11-17
removing the wellhead. Depending on the downhole
components associated with the tubing string, it is
possible and practical to remove an entire production
tubing string from a well without removing the wellhead.
The apparatus in accordance with the invention
also enables downhole operations, in particular near-
surface operations which require pressure containment.
Such operations include the drilling out of permanent
bridge plugs, cement plugs or any other obstruction in
the casing column near the surface during re-entries to a
well bore.
Although the apparatus in accordance with the
invention is versatile and robust, it may be easily
disassembled for transport to another well site. It can
also be transported without disassembly, permitting well
bores to be readily serviced at minimal cost.
BRIEF DESCRIPTION OF THE DRANINGS
The invention will now be explained by way of
example only, and with reference to the following
drawings wherein:
Fig. 1 is a cross-sectional view of a first
preferred embodiment of the apparatus in accordance with
the invention connected to a wellhead of a well bore;
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CA 02326268 2000-11-17
Fig. 2 is an elevational view of the apparatus
shown in Fig. 1;
Fig. 3 is an elevational view of a second
preferred embodiment of an apparatus in accordance with
the invention;
Fig. 3a is an enlarged cross-sectional view of
a connection between a stem and a lift rod joint in
accordance with the invention, showing the arrangement of
fluid circulation bores in each;
Fig. 4 is an elevational view of another
preferred embodiment of the apparatus in accordance with
the invention;
Fig. 5 is an elevational view of yet a further
preferred embodiment of the invention suitable for use in
shallow wells where production tubing string weights are
moderate; and
Fig. 6 is a cross-sectional view of the
apparatus shown in Fig. 1 connected to a telescoping
joint described in applicant's copending patent
application.
DETAILED DESCRIPTION OF THE PREFERRED EI~ODII~NT
This invention relates to an apparatus for
axially displacing a downhole tool or a tubing string in
a well bore equipped with a wellhead, the downhole tool
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CA 02326268 2003-11-04
being supported by the tubing string in a well to permit
axial displacement of the downhole tool or tubing string.
The apparatus in accordance with the invention may also
be used for performing downhole operations that require
pressure containment to ensure that hydrocarbons are not
released to atmosphere and concussive pressure releases
do not occur during such operations.
Fig. 1 shows a cross-sectional view of a first
preferred embodiment of an apparatus in accordance with
the invention, generally indicated by the reference 10.
The apparatus is mounted to a top of a wellhead generally
indicated by reference 12. Typically, the wellhead 12
includes a surface spool 14 and a master valve spool 16,
the structure of each being well known in the art . Some
wellheads do not include master valves. Mounted to a top
of the master valve spool 16 or an uppermost part of the
wellhead is a tool entry spool 18, which is the lowermost
component of the apparatus 10. The tool entry spool 18
accommodates a latch tool 96 (see Fig. 6) for connecting
a lift rod string 20 to a latch point 94 of a telescoping
j oint 90 or directly to a downhole tubular when the lift
rod string 20 is run into the well bore, as well as when
it is removed from the well bore, as will be explained in
detail with reference to Fig. 6. Mounted to a top
flange 19 of the tool entry spool 18 is an annular seal
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CA 02326268 2000-11-17
for containing well pressure, such as a blowout
preventer 22. As will be understood by those skilled in
the art, other annular seals for containing well pressure
can be adapted for use with the apparatus 10. For
example, certain stuffing box structures or multiple ram
type or annular preventers can be adapted for such use.
The blowout preventer 22 is preferred, however, because
of the ease of use and the security of the seal it
provides. Preferably, the apparatus includes two blowout
preventers 22 connected in sequence in order to increase
the safety of the apparatus and to provide extra room
between the master valve spool 16 and the uppermost
blowout preventer 22 to accommodate latch tools 96 of
different lengths. With two or more blowout preventers
safety is increased because the preventers can be opened
and closed in sequence at each lift rod joint connector
in the lift rod string to prevent tears in sealing
surfaces which can result from forcing rough surfaces at
the connectors through a closed preventer. For this
reason, it is preferable that the adjacent preventers be
spaced about 10-13 cm (4"-5") apart to accommodate a lift
rod joint connector between them.
Mounted to a top of the uppermost blowout
preventer 22 is a tool access spool 24 having at least
one tool window 26 or an integral locking mechanism (not
- 14 -
CA 02326268 2000-11-17
illustrated). The tool window 26 permits gripping or
locking devices to be inserted for engaging the lift rod
string. As will be explained below in some detail, the
tool window 26 permits the lift rod string 20 to be
gripped to permit joints to be added to, or removed from,
the lift rod string 20. It also permits the lift rod
string 20 to be locked against axial movement when joints
are being added to, or removed from, the lift rod
string 20. For example, the weight of the tubing
string 94 can be supported at the tool window 26 in low
pressure wells while lift rod string joints are being
added, or removed. If wells with exceptionally high
pressure are being worked, a lock inserted through the
tool window 26 prevents the lift rod string 20 from being
forced up out of the well bore while joints are being
added to, or removed from, the lift rod string.
The tool access spool can be replaced by a pair
of oppositely oriented well slip assemblies described in
United States Patent 3,846,877 to Spiri. Preferably, two
oppositely oriented slip tools are mounted to a top of
the uppermost blowout preventer 22. They may be operated
separately, or in unison, to control axial or rotational
movement of the lift rod string 20, as required by well
and/or operating conditions.
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CA 02326268 2000-11-17
Bolted to the top flange 25 of the tool access
spool 24 is a lower support plate 28 which is preferably
supported by a plurality of support posts 30a to reduce
compressive and torsional forces on the wellhead which
may be induced by the lifting and manipulation of heavy
production tubing strings. The number of support
posts 30a is a matter of design choice. Preferably at
least three are provided and four support posts 30a are
considered more appropriate for supporting the lower
support plate 28. Located above the lower support
plate 28 is an upper support plate 32 which is supported
by support posts 30b. The support posts 30b may be
integral extensions of support posts 30a or may be
separate posts which threadably engage threaded bores in
the lower support plate 28. For the sake of rigidity and
optimal support, it is preferable that the support
posts 30a and 30b be integral and that the support
posts 30a,b pass through bores in the lower support
plate 28. The support posts 30a,b may be secured to the
lower support plate 28 in any one of several ways well
known in the art, such as pins, wedges, set screws or the
like.
Reciprocally moveable between the lower support
plate 28 and the upper support plate 32 is a travelling
support plate 34. The travelling support plate 34
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CA 02326268 2000-11-17
includes bores 37 which receive the upper support
posts 30b with adequate clearance to permit the
travelling support plate 34 to move reciprocally between
the upper support plate 32 and the lower support plate 28
without undue resistance. The support posts 30b
stabilize the travelling support plate 34 and inhibit it
from rotational movement when a motor 36 is operated to
rotate the lift rod string 20. Affixed to the travelling
support plate 34 is the motor 36 for selectively rotating
the lift rod string 20. The stator 38 of the motor 36 is
mounted to the travelling support plate 34 and the
rotor 40 is attached to a link rod 42. The link rod 42
connects the lift rod string 20 with a piston rod 44 of a
hydraulic cylinder 46, which provides the motive of force
for axially displacing the lift rod string 20 and the
tubing string 94 to which it is attached, as will be
explained below in more detail with reference to Fig. 6.
The motor 36 may be a hydraulic motor or an electric
motor, for example. A hydraulic motor such as the
Bowen PS-60 Power Sub available from Bowen Tools, Inc., a
division of IRI International Corporation, is suitable
for most applications. An electric motor with equivalent
torque can also be used.
Interconnecting the link rod 42 and the piston
rod 44 is a swivel joint 48 which permits free rotation
- 17 -
CA 02326268 2000-11-17
of the link rod 42 with respect to the piston rod 44 to
permit the lift rod string 20 to be selectively rotated
without causing damage or wear in the hydraulic
cylinder 46. The hydraulic cylinder 46 is mounted to a
top surface 56 of the upper support plate 32 by one or
more mounting brackets 50 in a manner well understood in
the art.
Fig. 2 shows an elevational view of the
apparatus 10 shown in Fig. 1. As described above, four
supports posts 30a,b preferably support the lower support
plate 28, the upper support plate 32 and stabilize the
travelling support plate 34. In plan view, the
respective support plates 28, 32 and 34 may be square,
circular, hexagonal or any other convenient shape. The
travelling support plate 34 is shown in a position in
which the piston rod 44 is nearing an end of its stroke.
As described above, the travelling support plate 34
freely reciprocates between the lower support plate 28
and the upper support plate 32 with the extension and
retraction of the piston rod 44. The only other
component of the apparatus shown in Fig. 2 which was not
described above is a valve 52 preferably provided on the
tool entry spool 18. The valve 52 permits the release of
well pressure after the lift rod string 20 has been
withdrawn from a well and the master valve 16 has been
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CA 02326268 2000-11-17
closed but before the BOPS 22 are opened. Each BOP 22
also includes one or more of bleed off or equalization
valves 54, which are well known in the art. The
operation of the apparatus shown in Fig. 2 will be
described below with reference to Fig. 6.
Fig. 3 shows an elevational view of another
preferred embodiment of the apparatus in accordance with
the invention. The apparatus shown in Fig. 3 is similar
to that shown in Figs. 1 and 2 with the exception that
the travelling support plate 34 is eliminated and the
stator 38 of the motor 36 is mounted to a top surface 56
of the upper support plate 32. As shown in dotted lines,
the upper support plate includes a guide roller
assembly 58 through which a splined link rod 60 extends.
The splined link rod meshes with a splined hub (not
illustrated) of the rotor 40 (see Fig. 1) of the
motor 36. The splined link rod 60 reciprocates through
the splined hub to permit the lift rod string 20 to be
axially displaced. A swivel joint 48 connects the piston
rod 44 to the splined link rod 60 as described above with
reference to Fig. 1. The mounting brackets 50 which
support the hydraulic cylinder 46 are elongated to
support the hydraulic cylinder about the length of its
stroke above the upper support plate 32.
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CA 02326268 2000-11-17
The embodiment shown in Fig. 3 also illustrates
a further feature of the invention which may be
implemented in the embodiments shown in Figs. 1, 4 or 5
as well. In the embodiment shown in Fig. 3, a polished
rod 62 extends through a top end of the hydraulic
cylinder 46. The polished rod 62 is attached to the
piston of the hydraulic cylinder 46 and reciprocates with
the piston through seals in a top wall of the hydraulic
cylinder 46 in a manner well known in the art. A top end
of the polished rod 62 includes connectors 64 to which
fluid circulation hoses may be attached. The fluid
circulation hoses permit fluids to be circulated through
axial bores in the polish rod 62, the piston of the
hydraulic cylinder 46, the cylinder rod 44, the swivel
joint 48, the splined link rod 60 and each joint of the
lift rod string 20. The fluid circulation bores are
useful in certain instances where it is advantageous to
circulate fluid through the lift rod string 20. For
example, in certain gas wells it is not unusual to have
hydrate conditions near the top of the well bore in which
ice accumulates on tools and connections. In oil wells,
paraffins accumulate on tools and connectors. Under
either of these conditions, it is possible for a latch
tool 96 (Fig. 6) such as a spear, key, collet, friction
or slip type connector to freeze or become clogged with
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CA 02326268 2003-11-04
hydrates or paraffins. If that happens, it may not be
possible to release the latch tool 96 or move the lift
rod string 20 unless the latch tool 96 can be heated to
melt accumulated hydrate or paraffin deposits. It is
therefore advantageous to circulate heated fluid such as
heated oil through the lift rod string 20 when this
occurs to dissolve soluble solids. The fluid may also be
pumped through the lift rod string. The fluid may be one
or more of water, a water-salt mixture, a hydrocarbon
solvent or a mixture of hydrocarbon solvents.
Fig. 3a shows an enlarged cross-sectional view
of the connection between the lift rod string 20 and the
splined link rod 60. Joints in lift rod string 20 have
similar connectors. A fluid circulation bore 66 is an
axial bore which extends through each lift rod string
joint 20 and the splined link rod 60 so that the ends of
the bores are connected when the two are securely screwed
together. A recirculation bore 68 is radially offset
from the fluid circulation bore 66. Since the
recirculation bore 68 in one component may not align with
the recirculation bore 68 in the other component when two
joints are connected, a recirculation chamber 70 is
machined in the bottom of each female component of the
joint so that a fluid recirculation path is enabled even
though the two recirculation bores 68 are not aligned
when the components are securely connected. The swivel
joint 48 is constructed in the same manner to permit the
- 21 -
CA 02326268 2000-11-17
swivel joint to freely turn while ensuring that fluid
circulation is not inhibited.
Fig. 3a also shows a further feature of the
invention in which each joint of the lift rod string 20
includes opposed peripheral areas of reduced diameter to
provide parallel tool gripping surfaces 72 that are
adapted to be engaged by a clamping or securing device to
permit joints to be added to, or removed from, the lift
rod string 20 and to permit the lift rod string 20 to be
secured to prevent axial movement when joints are added
or removed. Clamping or securing devices used for this
purpose are well known in the art and may include
wrenches or hydraulic or mechanical clamps, all of which
are commercially available.
Fig. 4 shows yet another embodiment of the
apparatus 10 in accordance with the invention. The
embodiment shown in Fig. 4 is identical to the embodiment
shown in Fig. 1 with the exception that the hydraulic
cylinder 46 is replaced with a mechanical jack 74 that
has an axially displaceable jackpost 76, such as a ball
jack which is well known in the art. A lower end of the
jackpost 76 is affixed to the swivel joint 48 which is in
turn affixed to the link rod 42. Reciprocal movement of
the jackpost 76 is effected by rotation of a drive
shaft 78. The drive shaft 78 may be rotated by a
- 22 -
CA 02326268 2000-11-17
hydraulic motor, an electric motor or the like, as
appropriate. A mechanical jack such as the ball jack 74
is capable of securely moving significant loads and
provides a safe mechanism for shifting the position of
very long tubing strings in deep wells.
Fig. 5 shows another preferred embodiment of
the invention principally intended for use on shallow
wells where production tubing strings are of a weight
that is safely supported directly by the wellhead. In
this embodiment, support posts 80 are bolted directly to
a top flange 25 of the tool access spool 24. The number
of support posts 80 is a matter of design choice but at
least three are required and preferably at least four are
used. The top end of the support posts 80 are bolted
directly to a bottom flange 82 of a hydraulic cylinder 46
and supports the hydraulic cylinder 46 above the tool
access spool 24. A smaller version of the travelling
support plate indicated by reference 84 reciprocates with
movement of the piston rod 44 as explained above with
reference to Fig. 1. The stator 38 of the motor 36 is
mounted to the travelling support plate 84, as also
explained with reference to Fig. 1. In operation, the
apparatus shown in Fig. 5 functions the same as the
apparatus described above with reference to Figs. 1-4.
The apparatus is somewhat lighter and easier to handle,
- 23 -
CA 02326268 2000-11-17
which makes it ideal for use in areas where there are an
abundance of shallow wells that require service.
Fig. 6 is a cross-sectional view of the
apparatus 10 described above with reference to Figs. 1
and 2 mounted to a wellhead in which a production
tubing 94 produces oil from a formation B that bears gas,
oil and water. As is understood by those skilled in the
art, such wells may require frequent service in order to
maintain oil production as the gas/oil/water interface
moves upwardly or downwardly with the production of
hydrocarbons from the well. In certain areas, the
gas/oil/water interface may move upwards several feet
annually. In order to produce principally a selected
fluid from such formations, the applicant has invented an
apparatus generally indicated by reference 86 for
isolating fluid zones in a casing 88 of a well bore.
Periodically, the apparatus 86 must be repositioned
within the casing 88. This is accomplished using one of
the preferred embodiments of the apparatus 10 in
accordance with the invention. In an initial step in the
process, the apparatus 10 is attached to the top of the
wellhead 12 as described above with reference to
Figs. 1-5. If the well is a deep well, the apparatus is
preferably one of those described with reference to
- 24 -
CA 02326268 2000-11-17
Figs. 1-4. If the well is a shallow well, any one of the
apparatus shown in Figs. 1-5 may be used.
After the apparatus l0 is bolted to a top of
the wellhead 12, the adjustable support pads 31 located
respectively at the base of each support leg 30a are
adjusted so that the apparatus 10 is level and the
support legs 30a will share the load to be placed on the
apparatus 10 when the lift rod string 20 supports the
tubing string 94. Once the apparatus 10 is properly set
up, the lift rod string 20 is assembled using a plurality
of joints which are interconnected. Attached to a free
end of the first joint is a latch tool 96 for releasably
connecting to a latch point 92 of a telescoping joint 90
described in applicant's copending patent application.
The telescoping joint 90 permits the tubing string 94 and
the apparatus for isolating fluid zones 86 to be axially
displaced in the casing 88. The latch point 92 is
engaged by any one of a number of well known latch
tools 96 which may include quick-disconnect threads,
spears, keys, collets, friction or slip type tools,
releasable packers or rotary taper taps, each of which is
commercially available from several manufacturers and
well known in the art. The latch tool 96 is shown in an
engaged position with the latch point 92 at the bottom of
the telescoping joint 90. After the lift rod string 20
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CA 02326268 2000-11-17
has been extended down through the telescoping joint 90
and a connection with the latch point 92 has been
effected, the downhole tool 86 may be raised or lowered
within the range of the telescoping joint 90. This
permits a variety of downhole tool manipulations to
accomplish tasks such as those described in applicant's
copending patent application without setting up a derrick
or bringing in a crane, killing the well or performing
many of the other steps required using prior art methods.
To run the lift rod string 20 into the well, a
latch tool 96 is attached to a first joint of the lift
rod string 20 and the joint is connected to the stem 41
at the end of the link rod 42. The hydraulic cylinder is
extended until the tool grip surfaces 72 are in the tool
window 26 of the tool access spool 24. The tool grip
surfaces 72 are then engaged using a locking tool
inserted through the tool window 26, the motor 36 is
operated to release the stem 41 from the first joint of
the lift rod string 20, the piston of the hydraulic
cylinder is stroked back to the top of the cylinder 46
and another lift rod joint is added between the first
joint and the stem 41. The hydraulic motor 36 is
operated to make the connection between the first and
second joints of the lift rod string 20 and the stem 41.
The locking tool is then released from its grip on the
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tool grip surfaces 72 of the lift rod string 20, the
hydraulic cylinder 46 is stroked downwards until the tool
grip surfaces 72 of the second joint appear in the tool
window 26, and the process is repeated until the latch
tool 96 engages the latch point 92 of the telescoping
joint 90. After engagement of the latch tool 96 with the
latch point 92, the lift rod string 20 is tensioned to
remove weight from compression anchors, hangers or
packers 98 which support the tubing string 94 in the
casing 88, and the motor 36 is operated to rotate the
tubing string 94 by rotation of the lift rod string 20 to
release the anchors, hangers or packers 98. A production
packer 100 is released in the same way. Once the
anchors, hangers or packers 98 and the production
packer 100 are released, the tubing' string may be raised
or lowered in the casing 88 by adding or removing joints
of the lift rod string 20 as described above. When the
downhole tool 86 has been repositioned to a new location
in the well bore, the motor 36 is operated to reset the
anchors, hangers or packers 98 and the production
packer 100.
After the anchors, hangers or packers 98 and
the production packer 100 are reset, the latch tool 96
may be released from the latch point 92 using methods
well known in the art. For example, if the latch tool 96
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CA 02326268 2000-11-17
is a releasing spear, release is accomplished using a
"bump down" to break the attachment. The releasing spear
is then rotated two or three times to the right. The
rotation moves a releasing spear mandrel up through a
grapple of the releasing spear, forcing the grapple
against a release ring and putting the spear in the
released position. A straight upward pull will then
generally free the spear, however, it is recommended that
the spear be rotated slowly to the right when coming out.
The motor 36 is operated to accomplish the rotation. The
lift rod string 20 is then disassembled in reverse order
of the process described above for adding joints to the
lift rod string 20. After the latch tool 96 is withdrawn
above the wellhead 12, the master valve in master valve
spool 16 (see Figs. 1-4) is closed and well pressure is
bled off through the release valve 52 in the tool entry
spool 18. The BOPs 22 are fully opened after the well
pressure is bled off through the release valve 52, the
latch tool 96 is stroked up through the BOPS and the last
joint of the lift rod string 20 is removed. The
apparatus 10 may then be disconnected from the top of the
wellhead 12 and the well may be put back into production.
As will be understood by persons skilled in the
art, the apparatus in accordance with the invention may
be used to displace tubulars in a well bore that are not
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CA 02326268 2000-11-17
equipped with a telescoping joint. Spears, friction or
slip type tools may be used as latch tools to grip
downhole tubulars for displacing the tubulars to add or
remove joints, as required. Because of the structure of
the apparatus in accordance with the invention, this can
be accomplished while well pressure is contained, as is
well understood in the art.
The apparatus in accordance with the invention
can also be used for downhole operations which require
pressure containment. Such operations include the
drilling out of permanent bridge plugs, cement plugs or
any other obstruction in the casing. Normally, such
operations are required when abandoned well bores must be
re-entered. Consequently, the permanent bridge plugs,
cement plugs or other obstruction in the casing are
generally near the surface. In order to re-enter an
abandoned well, the apparatus 10 in accordance with the
invention is connected to a wellhead of the abandoned
well bore. If the well bore is not equipped with a
wellhead, a wellhead is installed before re-entry
operations are begun.
After the apparatus is set up, a hydraulically
driven bit is connected to the bottom of the tubular
which is ran down through the apparatus and fluids are
pumped through the tubular to operate the bit while the
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BOPs 22 contain any potential pressure release from the
re-entered well bore. Consequently, the removal of
permanent bridge plugs, cement plugs, or any other
obstruction in the casing can be safely and economically
performed without danger of release of concussive
pressures or hydrocarbons from the re-entered well bore.
Although only a few processes for the
relocation of a downhole tool has been described, it will
be understood by those skilled in the art that the
apparatus in accordance with the invention can be used
for any of the processes described in applicant's
copending application as well as processes that have yet
to be discovered. For example, it can also be used to
accomplish such tasks as setting plugs, packers or
subsurface safety control valves in a production tubing
string using the lift rod string 20 for running those
components into the tubing string. As will be understood
by those skilled in the art, there is no practical limit
to the length of a lift rod string 20, so even deep well
operations can be accomplished, if required. The light
weight and versatility of the apparatus make it ideal for
many operations now accomplished using much heavier rigs
which are more expensive to construct and maintain.
Changes and modifications to the embodiments
described above will no doubt become apparent to those
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CA 02326268 2000-11-17
skilled in the 'art. The scope of this invention is
therefore intended to be limited solely by the scope of
the appended claims.
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