Note: Descriptions are shown in the official language in which they were submitted.
Agent File No. 502.6
TITLE: QUARTER TURN TENSION TUBING ANCHOR
FIELD OF THE INVENTION
The present invention relates to tools for oil and gas wells generally, in
particular relates to a tension tubing anchor for anchoring a tubing string
and
downhole well equipment.
BACKGROUND OF THE INVENTION
Known tubing anchors use either a combination of right and left hand
threads for setting and unsetting, or are limited to one thread orientation.
Examples of such tubing anchors are shown in US patent no. 3,077,933 to
Bigelow and in Canadian patent no. 933,089 to Conrad. Disadvantages of such
tubing anchors include the expense of manufacturing the threaded portions, and
their tight tolerances are vulnerable to seizing, from corrosion and solids
including sand. Also they require 7 ¨ 9 rotations to set or unset, which makes
it
very difficult to set in the "S" bends and out in the horizontals of todays
wells and
to run cable down hole past the tension tubing anchor.
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Another type of tubing anchor shown in US patent no. 5,771,969 and
corresponding Canadian patent no. 2,160,647 to Garay avoids the
aforementioned threads and instead uses a helical bearing to transform
rotational movement into linear movement for setting and unsetting the tubing
anchor. The helical bearing also accommodates shear pins for secondary
unsetting if required. The use of one component namely the helical bearing to
perform several functions has the advantages over the previously-mentioned
prior art of being less expensive to manufacture and requires less rotation (2-
3
rotations versus 7-9).
However, there is a need for a tension tubing anchor that further improves
on these prior designs. In particular, there is a need for a tension tubing
anchor
that avoids the prior art threads and helical bearings that require multiple
full (i.e.
360 degree) rotations of the tubing anchor's mandrel to either set or unset
the
tubing anchor. The tension tubing anchor should not need to translate
rotational
movement into linear movement to engage the anchor slips with the well
conduit,
but rather should directly transfer a short longitudinal movement of the
mandrel
to extend the slips into gripping engagement with the well conduit. The
tension
tubing anchor should require only a limited rotation, such as rotation of less
than
360 degrees.
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SUMMARY OF THE PRESENT INVENTION
According to the present invention, a tension tubing anchor is provided for
anchoring well equipment in a well conduit to arrest movement of the
recipricating rod pump and connected well equipment by keeping the tension
tubing anchor and connected well equipment in tension, and also arrest
rotational movement.
The tubing anchor comprising:
a mandrel with an upward box end and a downward pin end connected to
the tubing proximate to the well equipment which may comprise a rod pump;
a cone element mounted to the mandrel and having a first conical surface
directed to the box end of the mandrel;
a drag body mounted on the mandrel housing, a drag means for
contacting the well conduit, the end of the drag body having a second conical
surface directed towards the first conical element;
a slip cage moveably mounted on the mandrel adjacent to and below
the drag body for housing the first conical element and a slip or a plurality
of
slips, each of the slips having an inner surface for cooperating with the
first and
second conical surfaces of the cone element and drag body respectively and an
opposed outer surface for gripping the well conduit, the slips having a
biasing
means for urging the slips inwardly toward the mandrel and away from the well
conduit;
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at least one drive pin running through the drag body, the end portion of
the drive pin protruding into a groove of the mandrel; and,
the mandrel having at least one groove for slideably receiving the end of
the the drive pin;
the groove having a longitudinal running arm for slidably receiving the
drive pin when the tool/tubing is run into the well or when work is being done
on
the well to ensure the tension tubing anchor does not prematurely set, another
longitudinal setting arm for receiving the drive pin when the mandrel is
lifted into
a set position, and a connecting arm;
wherein when the tubing anchor and related well equipment is at the
desired location in the well an initial upward pulling of the mandrel
relocates the
drive pin to the middle of the running arm,
wherein the mandrel is then rotated which relocates the drive pin to a
position in the setting arm,
and wherein the mandrel is then moved further upwardly such that the first
conical surface also moves upwardly (towards the box end of the mandrel),
which surface wedges under and moves the slips outwardly while the slip cage
and slips move toward the drag body such that the second conical surface of
the drag body also wedges under the slips as the conical surfaces come
together
until the outer surfaces of the slips grip the well conduit anchoring the
tension
tubing anchor to the well conduit.
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Further a method is provided for anchoring well equipment in a well
conduit for maintaining tension using a tubing anchor having:
a mandrel connected to the tubing or the well equipment;
a cone element mounted to the mandrel and having a first conical surface;
a drag body mounted on the mandrel, housing a drag means for
contacting the well conduit, and having a second conical surface;
a slip cage mounted on the mandrel adjacent to the drag body, housing
a slip or slips each having an inner surface, and an opposed outer surface for
gripping the well conduit, the slip or slips, or the slip cage having a
biasing
io means for urging the slip inwardly toward the mandrel and away from the
well
conduit;
the drag body having at least one pin and a portion of the pin protruding
toward the mandrel; and,
the mandrel having at least one longitudinal groove for each pin for
slideably receiving the protruding end of the pin;
wherein the method comprises:
exerting an initial upward pull on the mandrel causing the first conical
surface to move toward the second conical surface such that the first and
second conical surfaces contact the inner surface of the slip or slips and
urge the
zo slip or slips outwardly so that the outer surfaces of the slip or slips
grip the well
conduit.
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BRIEF DESCRIPTION OF THE DRAWING FIGURES
The preferred embodiment of the invention will now be described, by way
of example only, with reference to the accompanying drawings, wherein:
Figure 1 is a side view of a tension tubing anchor according to a preferred
embodiment of the present invention, shown in a run (unset) orientation
Figure 2 is a perspective view, in isolation, of a mandrel of the tension
tubing
anchor of fig.1 ;
Figure 3 shows the tension tubing anchor of fig.1 in a run position within a
segment of well conduit shown in cross-sectional view;
Figure 3a is a cross-sectional view of the tension tubing anchor and well
conduit along line 3a-3a of fig.3;
Figure 4 is a longitudinal section through the tension tubing anchor and
well conduit of fig 3 along line 4-4;
Figure 5 shows a set position of the tension tubing anchor of fig.3 in the
conduit; and,
Figure 6 is a longitudinal section through the tension tubing anchor and
well conduitof fig. 5, along line 6-6.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to figures 1 to 6, a preferred embodiment of a tension
tubing anchor, generally indicated by reference numeral 10, is shown inserted
within a well conduit 12, such as a wellbore casing. In these figures the
tension
tubing anchor is shown in an unset, or "run-in", orientation in which it can
be run
down and inside the well conduit on a tubing string, along with other well
equipment, such as a reciprocating rod pump.
In general and as is well known by persons of skill in the art the tension
tubing anchor has an upward, box end 22 and a downward, pin end 24, as
io shown in the figures. It is noted, that terms such as "up", "down",
"forward",
"backward" and the like used to identify certain features of the tension
tubing
anchor or directions of movement when placed in a well conduit is not intended
to limit the tension tubing anchor's use or orientation. The pin end 24 may
include a connection 14 for connecting to further downhole well equipment as
is shown in Figures 4, 5 and 6.
The tension tubing anchor has a tubular drag body 40 mounted over the
mandrel 20 to house a drag means in the form of multiple drag springs or drag
blocks 42. In the preferred embodiment four drag blocks 42 are generally
evenly
spaced circumferentially about the tubing anchor. Each drag block 42 has a
20 drag block spring 44 or a plurality of drag drag block springs 44 to
bias the outer
surface 46 of the drag blocks 42 against the well conduit's inner wall 13.
This in
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turn spaces the tubing anchor away from the inner wall 13 of the well conduit
12
and urges the drag body to remain stationary relative to the mandrel as the
tension tubing anchor is run in or otherwise moved within the inner wall of
the
well conduit. Upper and lower drag body retaining rings 50, 48 keep the drag
blocks 42 removably mounted within the drag body 40. Cap screws 52 attach
the upper drag body retaining ring 50 to the drag body 40. For illustrative
purposes, three circumferentially spaced cap screws 52. An alternative fixing
means is to thread the retaining ring 50 to the mandrel 20.
The drag body 40 is held to the mandrel by means of drive pins 88
lo connected to the drag body 40 which drive pins protrude into a groove or
grooves 80 in the mandrel 20 of the tension tubing anchor, as will be
explained in
more detail below.
A tubular slip cage 60, mounted on the mandrel 20 below the drag body
40 houses a single movable slip 62 or a plurality of movable slips 62.
References
to a plurality of slips will include a single slip and vice versa as the
context
requires. In the preferred embodiment three slips 62 are shown generally
evenly
spaced about the slip cage. Each slip 62 has an outer surface 63 with teeth
for
gripping the conduit wall 13 upon contact, and an inner surface.
To hold the slip cage 60 to the drag body 40, set screws 65 are fastened
to the drag body 40 and are located within elongate slots 66 spaced
circumferentially about the slip cage 60. The slots 66 with upper and lower
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shoulders 68a, 68b permit movement of the slip cage 60 relative to the drag
body 40.
The cone element 70 housed within the slip cage 60 is mounted on the
mandrel 20 by a plurality of circumferentially spaced fasteners in the form of
shear screws or shear pins 72 or any shearable or frangible means of
fastening.
The edge of the cone 70 opposite the shear pins 72 forms a first conical
surface
74 that faces towards the box end of the tension tubing anchor and when the
mandrel is moved upwardly, the first conical surface 74 wedges under the slips
62, moving the slips towards the well conduit 12 inner wall 13. Likewise, the
edge of the drag body 40 forms a second conical surface 54 facing the first
conical surface 74 and in operation in the setting step concurrently wedges
under the slips 62 and also moves the slips into a set position. However, the
first and second conical surfaces 74, 54 should not actively contact the slips
in
the unset position, as shown in fig. 4. A biaser in the form of a slip spring
76
is urges each slip 62 radially inwardly into the slip cage 60 and away from
the well
conduit 12 in the unset position (fig.4).
An important aspect of this tension tubing anchor is the configuration of
the at least one groove 80 formed in the mandrel's outer cylindrical surface
26,
best seen in fig.2. In the embodiment shown, the approximately j - shaped
zo groove has a first longitudual arm 86 operating as a running arm.
Another
second longitudinal arm 82 operates as a setting arm. Running arm 86 and
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setting arm 82 are connected. In the preferred embodiment they are connected
by a radial or circumferential arm 84 that acts as a connecting arm. The
grooves
80 are dimensioned (width, depth) to slidingly accommodate the drive pins 88.
The arrangement of drive pins 88 connected to the drag body 40 and protruding
into the grooves 80 provides a means for the mandrel 20 to move relative to
the
drag body 40 as well as a means for securing the drag body 40 to the mandrel
20 of the tension tubing anchor. In the embodiment shown throughout the
figures
multiple sets of grooves 80 and drive pins 88 are shown generally evenly
spaced
about the mandrel.
The operation of the tension tubing anchor may now be described with
reference to all figures, including figures 5 and 6 showing the tension tubing
anchor in the set position in the well conduit 12, and figure 2 showing the
pin 88
positions of the groove 80.
The tension tubing anchor 10 will have been run in to the well with the
is drive pins 88 located in the first running arm 86. The first step is to
initially pull
the mandrel upwardly by lifting the tubing string in the direction of arrow
16, so
that each of the drive pins 88 relocate along the running arm 86 to a position
about even with the connecting radial arm 84.
Next, the mandrel 20 is rotated to the right or clockwise when viewed from
the box end 22 of mandrel 20. Once the rotation relocates the pin 88 to the
start
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position of the setting arm 82 of the groove 80 of the mandrel 20, the tension
tubing anchor is positioned to be lifted into tension.
It can be understood that the radial arm 84 (and running arm 86) may be
oriented oppositely than shown in figure 2. Such would require a left or
counterclockwise turn of the mandrel 20.
Next, with reference to Figures 2, 5 and 6, the mandrel is lifted to set the
slips. The distance the mandrel 20 is required to be lifted depends on the
clearance between the outside surfaces of the slips 62 and the well conduit 12
inner surface 13 which distance can vary as is known by persons of skill in
the
art. As the mandrel 20 is pulled uphole, the cone element 70 is also lifted.
First
conical surface 74 of cone elements 70 wedge beneath and urge slips 62
outwardly. As the cone element's first conical surface 74 moves upwardly
towards the box end 22 of the mandrel 20, it moves towards the second conical
surface 54 of the drag body 40 such that the conical surfaces come together.
is The second conical surface 54 also wedges under the slips 62 until the
outer
surfaces of the slips 62 grip the well conduit 12 inner surface 13 anchoring
the
tubing anchor to the well conduit 12. The tubing string is pulled in tension
and
may be kept in tension as long as the set position is desired including by the
use
of means for maintaining tension at the surface of the well such means being
zo well known to persons of skill in the art.
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The tension tubing anchor is released, or unset, by reversing the above
described setting procedure. The mandrel 20 and first conical surface 74 of
cone element 70 are moved downwardly. As the conical surfaces 54, 74 are
moved away from each other a means 76 biasing the slips 62 inwardly cause the
slips to relocate in their unset position. This allows the tension tubing
anchor to
be moved to a different position in the well conduit 12 and be set again, or
removed from the well, by first relocating the pin 88 into the running arm 86
of
the groove 80.
It will be understood that while the groove design disclosed above is
io approximately "J" shaped, any configuration of the groove 80 is within
the ambit
of the invention providing it has a longitudinal setting arm for guiding the
mandrel
when setting the slips. Preferably a longitudinal running arm or drive pin-
accommodating position ensures that when the tension tubing anchor is run into
the well or the well is being worked on, any upward movement of the mandrel 20
Is will not prematurely set the slips, and preferably there is an arm for
connecting
the two longitudinal arms. It can also be understood that longitudinal arms
may
be oriented in the opposite position related to each other. It is also within
the
ambit of the invention to provide for any shape of a running arm or path that
provides a position to retain the drive pins 88 where it is not desired to set
the
20 slips, of a setting arm that provides enough longitudinal movement for
setting the
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tension tubing anchor, or any shape or orientation of connecting arm that
connects the two longitudinal arms.
An alternate method of unsetting the tension tubing anchor is to pull
tension on the tubing string to exert sufficient upward force (above the
tubing
weight) on the mandrel 20 which will shear the shear pins 72 by exceeding
their
maximum shear resistance. Once the shear pins 72 are sheared, the cone
element 70 becomes detached from the mandrel 20 and is free to move away.
Slip cages can be manufactured to provide a bypass area between the
slip cage and the conduit wall, sufficient to ensure fluids, gases and solids
like
io sand, may bypass the anchor. This in turn reduces the problem of a
recipricating
rod pump may become "gaslocked", wherein gases can be forced into the rod
pump.
Well operators desire to install elongate lines including cables, capillary
lines, sensors or diluent flow lines of various diameters thicknesses and
purposes, down the tubing and past the tension tubing anchor. The setting of
the
tension tubing anchor will not require the lines to be pre-wrapped around the
anchor as they must be in the prior art tubing anchors set by several
rotations of
the mandrel/tubing string. The problems with the extra cable that unwraps
include portions of it becoming caught between the slips or other parts of the
tubing anchor and the well conduit inner wall, or between the tubing itself
and the
well conduit inner wall.
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The above description is intended in an illustrative rather than a restrictive
sense, and variations to the specific configurations described may be apparent
to skilled persons in adapting the present invention to other specific
applications.
Such variations are intended to form part of the present invention insofar as
they
are within the spirit and scope of the claims below.
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