U.S. patent application number 10/696696 was filed with the patent office on 2004-07-01 for articulated slip ram for tapered coiled tubing.
Invention is credited to Van Winkle, Denzal Wayne.
Application Number | 20040124380 10/696696 |
Document ID | / |
Family ID | 32659285 |
Filed Date | 2004-07-01 |
United States Patent
Application |
20040124380 |
Kind Code |
A1 |
Van Winkle, Denzal Wayne |
July 1, 2004 |
Articulated slip ram for tapered coiled tubing
Abstract
An articulated slip for a slip ram includes a plurality of
articulated linked segments, attached to vertical pins or axles
which are parallel to the axis of a coiled tubing, for rotatable
movement of the linked segments. The articulated linked segments
are concave for abutting contact with a tubular through the slip
ram. The pins are mounted to a slip ram, which comprises a piston
within a cylinder, in the conventional manner for a blowout
preventer (BOP) ram. When the slip ram is actuated, the ram moves
forward, wrapping the articulated elements around coiled tubing in
a gripping motion, much like the fingers of a human hand.
Inventors: |
Van Winkle, Denzal Wayne;
(Santa Maria, CA) |
Correspondence
Address: |
Law Office of Tim Cook P.C.
P.O. Box 10107
Liberty
TX
77575
US
|
Family ID: |
32659285 |
Appl. No.: |
10/696696 |
Filed: |
October 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60421986 |
Oct 29, 2002 |
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Current U.S.
Class: |
251/1.3 ;
166/85.4 |
Current CPC
Class: |
E21B 33/06 20130101 |
Class at
Publication: |
251/001.3 ;
166/085.4 |
International
Class: |
E21B 033/06 |
Claims
I claim:
1. A slip comprising: a. a slip body; b. arms extending from the
slip body; c. a first set of vertical pins attaching the arms to
the slip body; d. a plurality of linked segments coupled to the
arms; and e. a second set of vertical pins linking the segments in
overlapping layers.
2. The slip of claim 1, wherein each of the linked segments defines
an arcuate interior surface.
3. The slip of claim 2, wherein the arcuate interior surface
defines threads.
4. The slip of claim 2, wherein the arcuate interior surface
includes a plurality of outwardly extending cones adapted to grip
the surface of a tubular.
5. A slip ram comprising: a. a body having a vertical bore defining
a vertical centerline and a horizontal bore extending laterally
from the vertical bore; b. a cylinder extending from the horizontal
bore; c. a piston within the cylinder; d. a piston rod extending
from the piston; and e. a slip coupled to the piston rod within the
horizontal bore, the slip comprising i. a slip body; ii. arms
extending from the slip body; iii. a first set of vertical pins
attaching the arms to the slip body; iv. a plurality of linked
segments coupled to the arms; and v. a second set of vertical pins
linking the segments.
6. The slip of claim 5, wherein each of the linked segments defines
an arcuate interior surface.
7. The slip of claim 6, wherein the arcuate interior surface
defines threads.
8. The slip of claim 6, wherein the arcuate interior surface
includes a plurality of outwardly extending cones adapted to grip
the surface of a tubular.
Description
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 60/421,986 filed Oct. 29, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
blowout preventers for tubing, and, more particularly, to a slip
ram in a blowout preventer adapted to accommodate tubing which
tapers or otherwise varies in its outside diameter.
BACKGROUND OF THE INVENTION
[0003] The use of blowout preventers in drilling, completion,
workover, and production of oil and gas wells is well known. Such
blowout preventers generally include a housing with a bore
extending through the housing. Opposed chambers extend laterally on
either side of the bore in the housing and communicate with the
bore. Rams within the chambers are connected to rods that are
supported for moving the rams inwardly into the bore to close off
the bore. This action divides the bore into a zone above the rams
and a zone below the rams. The rods also serve to retract outwardly
from the bore to open the bore.
[0004] Various types of rams may be employed such as those which
engage circumferentially around a pipe or tubular member for
sealing engagement with the tube or pipe, while others are provided
with cutting surfaces for shearing tubular members or cables which
extend through the bore of the blowout preventer.
[0005] Blowout preventers (BOPs) are also commonly used in coiled
tubing systems. Such BOPs provide a means of holding the tubing and
isolating the well bore pressure during a variety of conditions,
including emergencies. The configuration of the BOP rams and
sideport facility allows well-control operations to be conducted
under a variety of conditions.
[0006] Newer blowout preventers include four sets of rams, which
may be referred to herein as a "Quad BOP". The system comprises a
set of four stacked elements, each with a different function. Blind
rams are shut when there is no tubing or tool string extending
through the body of the BOP. Shear rams are designed to close on
and cut through the tubing. Slip rams close on and hold the tubing,
ideally without damaging the surface of the piping or other tubular
member. Finally, pipe rams seal around the tubing when it is in
place. Each of the rams should only be actuated when the tubing is
stationary; otherwise, damage to either the BOP or the tubing is
likely. Of the four types of rams just described, the present
invention is directed to the slip ram type for use with tubing.
[0007] As previously explained, a slip ram closes onto a tubular,
and in the case of the present invention, closes on and holds
tubing. Slip segments to grip and suspend coiled tubing are well
known and widely used in coiled tubing applications. The slips are
typically installed in a set of rams. The slips are most often made
in two pieces, one piece in each ram, with gripper teeth on the
semi circle resulting in near 360.degree. coverage of the coiled
tubing diameter. The gripper section is machined to a specific
inside diameter to match the outside diameter of the coiled tubing.
This system works reasonably well as long as the coiled tubing is
of a constant diameter. Over-worked coiled tubing may become
undersized, oversized, or out of round, all of which reduce, or
negate the effectiveness of the slip segment gripper teeth.
[0008] Furthermore, recent innovations have provided tubing which
has a substantially constant inside diameter, but a substantially
constantly increasing outside diameter, so that the tubing presents
a tapered aspect in its outside diameter. Development of such a
tapered outside diameter coiled tubing renders the gripping system
with a set diameter unworkable. In other words, with a first length
of tubing through the slip ram, a relatively small diameter of
tubing must be accommodated by the slip ram. However, with a longer
length of tubing down hole, a larger diameter of tubing must be
grasped and held. Current structures of slip rams offer a set
diameter of the ram, provided in equal halves on either side of the
tubular, and this is incapable of accommodating the varying
diameter of tubing which is presented to the slip ram, if the
outside diameter of the tubing varies with length. It is believed
that the prior art has failed to solve, or even address this
problem.
SUMMARY OF THE INVENTION
[0009] The present invention addresses these and other needs and
drawbacks in the prior art by providing a slip and a method of
gripping tubing having a varying outside diameter. The slip is
configured to be retrofitted on existing slip rams in the field so
save on costs, and to accommodate such varying diameter tubing when
called for by a specific job.
[0010] In a first aspect, the present invention comprises an
articulated slip for a slip ram. The slip includes a plurality of
articulated elements, attached to vertical pins or axles which are
parallel to the axis of the tubular, for rotatable movement. The
articulated elements are concave for abutting contact with a
tubular through the slip ram. The pins around mounted to a slip
ram, which comprises a piston within a cylinder, in the
conventional manner for a blowout preventer (BOP) ram. When the
slip ram is actuated, the ram moves forward, wrapping the
articulated elements around the tubular in a gripping motion, much
like the fingers of a human hand.
[0011] The present invention provides a further innovation, other
than providing a slip which can grasp a tubular with a varying
outside diameter or out of round diameter, and that innovation
deals with the irregular surface within the ram itself which
contacts the tubing. Although slip rams ideally do not damage the
tubing surface of the tubular member through the BOP, it has been
found that even a single actuation of the slips against the tubing
can score the exterior surface of the tubing. In today's high
performance operations at elevated pressures, this scoring can
reduce the useful lifetime of the tubular member, particularly with
coiled tubing. The interior surface of slips commonly in use today
comprises a series of parallel horizontal toothed surfaces, or a
series of threads in a substantially horizontal orientation, to
contact the tubular and prevent vertical, i.e. axial movement of
the tubular. The present invention is further directed to reducing
the scoring on the outside surface of the tubular by the slips when
engaging and disengaging.
[0012] Thus, in another aspect of the invention, a method of
retaining a tapered tubular within a well bore is provided, wherein
an articulated slip is impressed upon the tubular by wrapping the
slip around the tapered tubular, the extent of closure of the slip
determined solely by the outside diameter of the tubular. In a
still further aspect of the invention, a cast or molded slip
surface comprises a plurality of cleats defining a conical aspect
up to a substantially spherical apex of the cone, in order to
develop point loading of the cleats on the outside surface of the
tubular, rather than the scoring action of linear lands of threads
on the surface of the slip, as common in the art.
[0013] These and other features and advantages of this invention
will be readily apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the above recited features,
advantages and objects of the present invention are attained and
can be understood in detail, more particular description of the
invention, briefly summarized above, may be had by reference to
embodiments thereof which are illustrated in the appended
drawings.
[0015] FIG. 1 is an elevation section view of an actuator and
coiled tubing slip ram constructed in accordance with the teachings
of the present invention.
[0016] FIG. 2 is a top view, in partial section, of a set of slips,
i.e. from both sides of a tubular, of the present invention.
[0017] FIG. 3 is a front elevation view, i.e. toward an actuator,
of the slip of this invention.
[0018] FIG. 3A is a top section taken along section lines A-A of
FIG. 3.
[0019] FIG. 3B is a side section view taken along section lines B-B
of FIG. 3.
[0020] FIG. 3C is a side section view taken along section lines C-C
of FIG. 3.
[0021] FIG. 4A is a top view of a set of linked segments in an
actuated position, i.e. positioned against a coiled tubing.
[0022] FIG. 4B is a top view of the linked segments in a retracted
position.
[0023] FIG. 5 is a perspective view of a first type of contact
surface for a segment.
[0024] FIG. 6A is a top view of a segment of FIG. 5.
[0025] FIG. 6B is a side section view of the segment of FIG.
6A.
[0026] FIG. 7A is a top view of a segment having a second, low
stress contact surface.
[0027] FIG. 7B is a side section view of the segment of FIG.
7A.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0028] FIG. 1 illustrates the slip of the present invention in its
intended environment. An actuator 10 includes a cylinder body 12
enclosing a cylinder chamber 14 having a piston 16 therein. A close
port 18 directs hydraulic fluid pressure to one side of the piston
to close the ram, and an open port 20 directs hydraulic fluid
pressure to the other side of the piston to open the ram. The
piston 16 connects to a rod 22 which terminates at a flange 24
which connects to a slip 26 of this invention, shown and described
below in greater detail.
[0029] The slip 26 moves within a body 28 of a blowout preventer
which is aligned along a center axis 30. It is to be understood
that a similar slip (not shown in FIG. 1) is positioned opposite
the slip 26 to enclose a coiled tubing 32 passing through the
blowout preventer. Upon actuation, the slip 26 closes in around the
coiled tubing 32 in a manner to be described below.
[0030] FIG. 2 illustrates a complementary set of slips 26 and 26'.
In the following description, the components of the slip 26 will be
described and it is to be understood that the slip 26' includes the
same structure. The flange 24 (FIG. 1) mounts within a flange
cavity 34 to move the slip by way of the actuator. The slip
includes a slip body 36 to which are attached a first arm 38 and a
second arm 40. The arms 38 and 40 are mounted to the body with
vertical pins 42 and 44, also as shown in FIG. 3C. The arms 38 and
40 are also pinned at their opposite ends by pins 46 and 48 to a
stack of overlapping, articulated linked segments 50. The linked
segments are shown in FIG. 2 in the actuated position, in contact
with the coiled tubing 32 centered on the axis 30.
[0031] Note also the positioning of a set of articulated segments
70, 72, and 74 for ease of explanation of FIGS. 4A and 4B,
described below.
[0032] FIG. 3 shows a front elevation view of the stack of linked
segments 50. Each such segment has an arcuate interior surface 52
(See FIG. 5) adapted to grip the outside surface of the coiled
tubing 32. The segments are offset from one row to the next, much
as bricks are offset in the construction of a brick wall. As shown
in FIG. 3A, the pin 48 couples a segment 54 to the arm 40, and the
segment 54 also includes a pin 56. A segment 58 is adjacent the
segment 54 on the same layer, and includes pins 60 and 62 for
rotational movement therewith. A segment 64 (See also FIG. 3B),
located below the segments 54 and 58, is pinned to the pin 56 of
segment 54 and the pin 62 of segment 58, and thus is articulated in
respect of these segments. The other segments are similarly offset,
from one layer to the next, down the stack.
[0033] The stacking of the respective linked segments is also
illustrated in FIG. 3B. Each of the alternating layers overlaps the
layer above and below it (except of course for the top and bottom
layers), to provide full diameter contact between the surfaces 52
and the coiled tubing.
[0034] The slip body also includes line guides 66 on either side of
the body for mating engagement with the opposite slip body. The
slip body may preferably include a line guide on the bottom of the
body, and a similar line guide on the top of the body.
[0035] FIGS. 4A and 4B illustrate the actuation of the linked
segments, from a retracted position, as shown in FIG. 4B, to a
closed position, as shown in FIG. 4A. The arms 38 and 40 (FIG. 2)
are moved forward toward the axis 30, thereby moving the pins 46
and 48 forward as well, and the articulated segments, linked
together, collapse around the coiled tubing 32.
[0036] FIGS. 5, 6A, and 6B depict a first embodiment of a segment
80 having the arcuate interior surface 52. The surface 52 if
preferably formed of substantially horizontal threads 72 (FIG. 6B)
with vertical channels 74 cut through the threads to clear debris
from the threads 72 and to avoid a continuous stress riser around
the tubing. This arrangement somewhat resembles the interior
surface of conventional slips, known in the art.
[0037] However, FIGS. 7A and 7B illustrate a new interior surface
82 of the presently preferred mode of the invention. The surface 82
preferably includes a plurality of molded cones 84 or cleats, each
of the cones having a rounded apex, in order to properly grip the
coiled tubing, while eliminating the scoring action of the threads
of the embodiment of FIGS. 6A and 6B.
[0038] It should also be apparent to those skilled in the art that
the present invention may find application in other operations
requiring the gripping of coiled tubing which may not have uniform
outer diameter. For example, the variable diameter, articulated
gripper of this invention may be used in a coiled tubing injector,
which requires the temporary gripping of the coiled tubing as it is
injected into and withdrawn from the borehole.
[0039] The principles, preferred embodiment, and mode of operation
of the present invention have been described in the foregoing
specification. This invention is not to be construed as limited to
the particular forms disclosed, since these are regarded as
illustrative rather than restrictive. Moreover, variations and
changes may be made by those skilled in the art without departing
from the spirit of the invention.
* * * * *