Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR CONTROLLING A TOOL HAVING A MANDREL
THAT MUST BE STROKED INTO OR OUT OF A WIELL
TECHNICAL FIEhD
The present invention relates to equipment for
servicing oil and gas wells and, in particular, to an
apparatus for controlling a tool having a mandrel~or
ether tubular that must be stroked into or out of a high-
pressure well.
BACKGROUND OF THE INVENTION
Most oil and gas wells eventually require same form
of stimulation to enhance hydrocarbon flow in order to
make or keep them economically viable. The servicing cf
oil and gas wells to stimulate production requires the
pumping of fluids under high-pressure. The fluids are
generally corrosive and abrasive because they are
frequently laden with corrosive acids and abrasive
propants such as sharp sand.
Wellheads are not designed to accommodate delivery
of high-pressure, abrasive fluids into the well.
Consequently, isolation tools in various forms and
configurations have been invented to protect wellheads
during well stimulation processes. As knowledge of_ well
stimulation processes have developed, the importance of
high delivery rates for successful and economic
stimulation processes has been appreciated.
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Consequently, it is now Applicant's practice to run large
bore mandrels through blowout preventers (BOPs) mounted
to a well in order to enhance stimulation effects and
reduce job time.
Because of the very nature of the stimulation
process, most wells to be stimulated have relatively low
natural pressure before the stimulation process
commences. There are, however, exceptions which may
require high-pressure wells to be stimulated for various
reasons. In any event, once stimulated, the well may be
under very high-pressure. The high-pressure may result
from the use of energized stimulation fluids, well known
in the art, or natural pressu re developed as a result of
opening up a high-pressure area of a production zone.
Consequently, situations exist in which the
insertion of mandrels used to safely conduct high-
pressure fluid through BOPS and other wellhead components
or the removal of such mandrels from the wellhead
requires mechanical control that cannot be provided by a
service rig or a boom truck. For example, a well
stimulated with energized fluid may overbear the weight
of the mandrel with attached tools and tubing strings.
In such situations, the well must be killed before a
mandrel can be safely removed. As is wel.1 understood in
the art, kill fluids are expensive and killing the well
may reverse all or part of the beneficial effects of the
stimulation process.
Methods and equipment have been devised for
inserting these mandrels for protecting wellhead
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equipment under high-pressures. Examples of these are
taught in United States Patents Number 4,241,786,
4,867,243 and 6,470,965.
United States Patent Number 4,241,786 issued to
Bullen on December 30, 1980, and is entitled WELL TREE
SAVER. The apparatus includes a base flange connected to
a pair of hydraulic Cylinder pistons. Cylinder tops of
the hydraulic cylinders are rigidly secured to the
mandrel that is supported over top the well, so that
motion of the cylinders relative to the pistons induces
corresponding motion of the mandrel within the well. As
will be evident to those skilled in the art, there is
little space available for connecting a single high-
pressure stimulation fluid supply line (i.e. a "frac"
line) to a high-pressure Valve that controls fluid
passage through the mandrel, as the cylinders obstruct a
substantial portion of a top end of the mandrel, where
the high-pressure valve is located. This limited access
becomes increasingly problematic when a rig is used
parallel with, and proximate the well equipment, as the
rig frequently obstructs a substantial part of the
mandrel.
United States Patent Number 4,867,243, entitled
WELLHEAD ISOLATION TOOL AND SETTING AND METHOD OF USING
SAME, which issued to Garner et al. on September 19,
1989, teaches a method of using an apparatus having a
single hydraulic cylinder for raising the mandrel from a
well under pressure. While meritorious, this apparatus
does not permit fluid access to the mandrel. Rather, the
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mandrel is stroked in, and the apparatus is removed, and
then well stimulation equipment is mounted to the
mandrel.
United States Patent Number 6,470,905, entitled
DEVICE FOR INTRODUCING A HIGH-PRESSURE FLUID INTO WELL
HEAD COMPONENTS, issued on October 29, 2002 to Winter.
The device includes two piston cylinders also close to
the mandrel, with cylinders that extend above the mandrel
top end, and accordingly provide limited access to
fracturing lines.
Other devices are known for performing the insertion
and removal of a casing mandrel within a well. For
example the substitution of the hydraulic cylinders with
respective screw jack assemblies is taught in United
States Patent Number 4,632,183, entitled INSERTION DRIVE
SYSTEM FOR TREE SAVERS, which issued to McLeod on
December 30, 1986. The jack assemblies also extend
above, and in parallel with, the casing mandrel,
obstructing access by the fracturing lines and equipment.
A further problem with current mandrel insertion
equipment is that it is a single-purpose device. In
general, different equipment is required to lift and land
a tubing string, and to perform other like operations
(such as a rig or a boom truck, well known in the art).
The expense of the single-purpose device makes a higher
cost per use of mandrel insertion equipment, and
increases the amount and cost of equipment required on-
site. Further the alternating use of one lifting/setting
device for one function, and then a second
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lifting/setting device for a next function requires
installation and removal of the lifting/setting devices,
which adds time and expense to wellhead servicing
operations.
Consequently, there exists a need for an apparatus
for controlling vertical motion of a tubular within a
high-pressure well that provides unobstructed access to a
top end of the tubular, and is adapted to permit rotation
of the tubular, so that the apparatus can also be used
for removing and landing a tubing string, etc.
SUML~ARY OF THE INVENTION
It is therefore an object o~F the invention to
provide an apparatus for controlling vertical movement of
a tubular within a high-pressure well.
It is a another object of the .invention to provide
an apparatus for controlling vertical movement of either
a high-pressure mandrel used for wellhead isolation, a
landing joint, or other tubulars, within a high-pressure
well, so that the apparatus is adapted to perform a
plurality of operations.
It is a further object of the invention to provide
an apparatus for controlling Vertical movement of a
tubular within a high-pressure well while providing
unobstructed access to a top end of the tubular.
The invention therefore provides an apparatus for
controlling vertical movement of a tubular in a wellbore.
The tubular may be a high-pressure mandrel of a well
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stimulation tool or a wellhead isolation tool, or may be
a landing joint. The apparatus includes an anchor spool
with a bottom flange for mounting to the top of the high-
pressure well in a fluid-tight seal. A top end of the
anchor spool supports a high-pressure packing that seals
an annulus between the top end and the tubular, while
permitting vertical and rotational motion of the tubular.
The anchor spool provides an anchor plate having
connectors for detachably securing bottom ends of at
least two piston cylinders symmetrically disposed about
the anchor spool. The piston cylinders are a part of a
detachable superstructure, and a tool support structure
that has an adapter stack bottom end for secure
connection to the tubular. The tubular may be connected
directly or via one of a swivel joint, a tool that
includes the tubular, and an adapter connected directly
or indirectly to the tubular. Accordingly, activation of
the piston cylinders causes vertical motion of the
tubular within the high-pressure well.
The anchor spool preferably includes an elongated
sidewall between the bottom flange and the top end. The
elongated sidewall defines a passageway through the
anchor spool having a diameter large enough to receive a
tubing hanger. The apparatus can therefore be used to
remove or land a tubing hanger in a tubing head spool.
The tool support structure includes a control plate
that interconnects cylinder ends of the at least two
piston cylinders. By providing for connection to the
piston cylinders from below, the top side of the control
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plate is above the piston cylinders. The top side of the
control plate includes a universal adapter that is in
fluid communication with a fluid passage through the tool
support structure. A union adapter in fluid
communication with the fluid passage is mounted to a
bottom side of the control plate. The union adapter
preferably has a bottom end that terminates in a wing
union that provides the adapter and permits rapid
connection to the tubular.
In accordance with yet anot:~er aspect of the
invention, a second apparatus for controlling vertical
movement of a tubular within a high-pressure well is
provided. The second apparatus includes an anchor spool
that has a bottom flange for secure, fluid-tight
connection atop the high-pressure well, and provides a
sealed passageway through which the tubular can be
vertically displaced. A tool support structure of the
second apparatus includes an adapter stack bottom end for
secure connection to the tubular in a same manner as that
of the first apparatus. At least two piston cyl~_nders
symmetrically disposed about the tubular are secured to a
bottom of the tool support structure and to the anchor
spool, so that a top end of the tubular can be accessed
at an adapter stack top end of the tool support
structure.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present
invention will become apparent from the following
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detailed description, taken in combination with the
appended drawings, in which:
FIG. 1 is a schematic side elevational view of the
apparatus in accordance with the invention for
controlling vertical movement of a tubular within a high-
pressure well;
FIG. 2 is a schematic side elevational view of the
apparatus shown in FIG. 1 with a detachable
superstructure of the apparatus detached from an anchor
spool of the apparatus;
FIG. 3 is a schematic side-elevational view of the
apparatus shown in FIG. 1 with a landing joint connected
to a tool support structure of the apparatus, and the
hydraulic cylinders in an extended condition;
FIG. 4 is a schematic side-elevational view of the
apparatus shown in FIG. 3 with the hydraulic cylinders in
a retracted condition;
FIG. 5 is a schematic side-elevational view of the
apparatus shown in FIG. 1 connected to a. well stimulation
tool, with the hydraulic cylinders in an extended
condition; and
FIG. 6 is a side-elevational view of the apparatus
shown in FIG. 5 with the hydraulic cylinders shown in a
retracted condition.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention provides an apparatus for controlling
vertical movement of a tubular that is designed tc be
inserted into a high-pressure well. The apparatus
includes an anchor spool, a tool support structure above
the anchor spool, and a plurality of symmetrically
disposed piston cylinders interconnecting the two. The
tubular may be a landing joint or a high-pressure mandrel
of either a well stimulaticn tool, or a wellhead
isolation tool. The apparatus therefore has multiple
uses. The apparatus further provides unobstructed access
to a top end of the tubular because the piston cylinders
are connected to a bottom side of the tool support
structure. The piston cylinders are radially distributed
to provide a balanced control force to permit
installation of a well stimulation tool, or a wellhead
isolation tool connected to the tool support structure.
FIG. 1 is a schematic side-elevational view of the
apparatus 10 in accordance with an embodiment of the
invention. The apparatus 10 includes an anchor spool 12
and a detachable superstructure 26. The anchor spool 12
includes a bottom flange 14, an elongated sidewall 16,
and a top end 17 with a threaded adapter 18 for threaded
connection of a lock-down nut, as will be described below
in more detail. An axial passage through which the
tubular can pass is formed through the anchor spool 12.
The axial passage through anchor spool 12 is defined by
an interior of the elongated sidewall 16, as can be
readily seen in FIG. 1. The top end 17 also includes a
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packing cavity 20 for receiving and supporting a high-
pressure packing, such as a Chevron packing that is well
known in the art. The anchor spool 12 further includes
an anchor plate 22 that extends laterally in at least two
directions from the elongated sidewall 16. The anchor
plate 22 is preferably welded to an outer periphery of
the elongated sidewall 16 and, in one embodiment, is
reinforced by gussets 24 welded between the anchor
plate 22 and the elongated sidewall 16 to provide
additional stabilizing support. The anchor spool 12 is
constructed to safely contain pressures of at least
10,000 psi.
The detachable superstructure 26 includes at least
two hydraulic cylinders 28 having ram ends 28a and
cylinder ends 28b. The RAM ends 28a are detachably
connected to the anchor plate 22 by threaded
connectors 29, such as wing nuts, well known in the art.
The threaded connectors 29 are a-rr_ayed symmetrically
about the axis of the anchor spool 12. The RAM ends 28a
of the hydraulic cylinders 28 are equipped with
stabilizers 31 to enlarge a footprint of the RAM ends,
and therefore provide additional stability between the
anchor plate 22 and the hydraulic cylinders 28. The
hydraulic cylinders 28 are one example of piston
cylinders.
The cylinder ends 28b of the hydraulic cylinders 28
are rigidly interconnected by a tool support structure
that includes a control plate 30. The control plate 30
also supports an adapter stack 32. The adapter stack 32
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includes a universal adapter 34 mounted to a top of a
union adapter 36. The universal adapter 34 extends above
the control plate 30. The union adapter 36 extends below
the control plate 30, and supports a wing union 38 used
to support a tool adapter 40. A fluid passage 42 through
the tool support structure extends through the tool
adapter 40, the union adapter 36 and the universal
adapter 34. The adapter stack 32 is mounted to the
control plate 3U by bolts 44 received in bores through a
flange 46 of the union adapter 36.
As shown in FIG. 2, when the threaded connectors 29
are removed from the RAM ends 28a of the hydraulic
cylinders 28, the detachable superstructure 26 can be
removed from the anchor spool 12. As will be understood
by those skilled in the art, it is not unusual that a
well to be stimulated has low natural pressure prior to
the stimulation operation. Consequently, the anchor
spool 12 can be used independently of the
superstructure 26 when a well tool is inserted into a
low-pressure well, since th.e weight of the tool with
attached mandrel and, optionally, attached tubing string
will overbear wel.1 pressure and the tool can be readily
inserted into the well. However, the anchor spool is
preferably used whenever well stimulation is performed to
provide a means of controllably extracting the mandrel
from the well if energized fluids are used for well
stimulation andlor a high-pressure formation is opened up
during the well stimulation process. When either
situation occurs, the superstructure 26 is mounted to the
anchor_ spool 12 and the hydraulic cylinders 28 are
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operated to controllably stroke the mandrel out of the
well, so that a bottom of the mandrel is above a BOP to
which the anchor spool is mounted. Once rams of the BOP
are closed, pressure can be bled off from the anchor
spool 12 using a pressure bleed port, 47 vn a manner well
known in the art.
FIG. 3 is a schematic side-elevational view of the
apparatus 10 in which the tool adapter 40 is connected to
a. landing joint 50 used to remove a tubing hanger from a
tubing head spool of the well or insert the tubing hanger
into the tubing head spool, as described in Applicant°s
United States Patent No. 6,595,297 which issued on July
22, 2003. The landing joint 50 is preferably connected
to the tool adapter 40 by a swivel joint 52. The tool
adapter 40 is normally mounted to a tool adapter
flange 41 connected to a top of the landing joint 50, or
the optional swivel 52. Consequently, the landing
joint 50 is connected to and disconnected from the
detachable superstructure 26 using the wing union 38.
As shown in FIG. 3, a landing joint 50 extends
through a wing nut 54 that engages the threaded
adapter 18 on the top end of the anchor spool 12. The
wing nut 54 secures a packing retainer nut 58, which in
turn retains and compresses a Chevron packing 56 in a
packing cavity 20 of the anchor spool 12 to provide a
seal around the landing joint. This permits the landing
joint 50 to be reciprocated through the anchor spool 12
as it is stroked into and out of the well, and further
permits rotational movement of the landing joint 50. As
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noted above, the use of the landing joint 50 is described
in detail in Applicant s United States Patent
No. 6,595,297.
FIG. 4 shows the landing joint 50 stroked down into
the well to a position where it is connected to a top of
the tubing hanger. After the landing joint is connected
to the tubing hanger, the tubing hanger and connected
tubing are raised into the anchor spool 12 using the
hydraulic cylinders 28 in a manner well known in the art.
Tubing rams of a BOP to which the anchor spool 12 is
mounted are closed, pressure is bled off through the
pressure bleed port 47 in the anchor spool 12 and the
apparatus 10 is hoisted by connecting a lifting sub to
the universal adapter 34, and hoisting the entire
apparatus along with the tubing hanger (not shown) and
attached tubing (not shown) using a service rig, in a
manner well known in the art.
FIG. 5 is a cross-sectional schematic view of the
apparatus 10 in accordance with the invention mounted to
a well stimulation tool described in United States Patent
Application No. 09/537,629 which was filed on March 29,
2000. The well stimulation tool 60 includes a fracturing
head 62. The well stimulation tool 60 is connected to a
top of the anchor spool 12 by a lock-down nut 54. The
function and use of the well stimulation tool 60,
referred to as a blowout preventer protector in
Applicant's pending application, is thoroughly explained
in the specificat3.on of which is incorporated herein by
reference. As shown in FIG. 5, the well stimulation
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tool 60 includes a mandrel that is fully inserted through
the wellhead and a cup tool 66 that is sealingly engaged
with a casing of the well (nct shown).
If energized fluids are used to stimulate the well
or a high-pressure formation is opened up during the
stimulation process, pressure in the well may be toc high
to safely remove the well stimulation tool. 60 without the
use of the apparatus 10 in accordance with the invention.
Consequently, the superstructure 26 is connected to the
anchor plate 22 using the threaded connectors 29 and the
wing union 38 to connect the union adapter 36 to the tool
adapter 40.
FIG. 6 shows the well stimulation tool 60 stroked
out of the well using the apparatus 10. As is apparent,
the hydraulic cylinders 28 are in an extended condition
and the cup tool 66 is received within the anchor
spool 12. Consequently, blind rams 72. of BOP '70 (FIG. 5)
can be closed. Thereafter, pressure is bled from the
anchor spool 12 using the pressure bleed port 47, which
permits the entire apparatus including the
superstructure 26 and the anchor spool 12 to be removed
from the BOP 70. Thereafter, fluid control equipment can
be connected to a top of the BOP 70 and the stimulation
fluids can be flowed back out of the well in a manner
well known in the art.
As will be appreciated by those skilled in the art,
wing union 38 permits different tools, such as the
landing joint 50 (FIG. 3) and the well stimulation
tool 60 (Fig. 5) to be rapidly connected and disconnected
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from the apparatus 10 in accordance with the invention.
This makes the apparatus 10 very adaptable and permits a
plurality of well stimulation procedures to be performed.
The apparatus 10 is adapted to be used to insert
substantially any tubular into a high-pressure well or
remove the tubular from the well. In fact, the
apparatus 10 is also useful for low-pressure applications
as will be well understood by those skilled in the art.
The rapid connection and disconnection of different tools
therefore provides a very versatile control mechanism
adapted for use in a wide variety of applications.
The embodiments of the invention described above are
intended to be exemplary only. The scope of the
invention is therefore intended to be limited only by the
scope of the appended claims.
