Note: Descriptions are shown in the official language in which they were submitted.
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MOVABLE WELLHEAD PLATFORM
FIELD OF THE INVENTION
This invention relates generally to the field of temporary work platforms
for oil and gas wellheads and more particularly to platforms designed for
facilitating different types of work being performed on or around wellheads in
the absence of drilling rigs.
BACKGROUND OF THE INVENTION
Producing oil and natural gas wells occasionally requires major repairs or
modifications, called "workovers." A workover may last anywhere from a few
days to several weeks to accomplish. Workover services are occasionally
carried
out with the same type of rig used to perform maintenance services, although
the rig often is outfitted with specialized equipment including rotary
drilling
equipment, mud pumps, mud tanks and blowout preventers. In many cases it is
convenient to perform workovers in the absence of drilling rigs. Such workover
examples may require the use of endless tubing units, wire line units,
snubbing
units and fracture stimulation units for example. In addition to workover of
an
existing well, various tasks need to be performed to plug a well whose useful
lifetime is finished. These tasks are typically described as "completion"
tasks.
The completion process may involve selectively perforating the well casing at
the depth of discrete producing zones and installing down-hole equipment.
Workover or completion tasks may take anywhere from a few days to several
weeks to accomplish.
In most cases when such workover completion work is being performed
on a welihead, ordinary modular-type scaffolding is erected around the
wellhead
so that workers can access the equipment vertically erected around the
wellhead. This scaffolding is inconvenient for several reasons. It takes
significant time to assemble and certify for safety, it can be unstable on
frozen
ground that is subject to thawing by steam heaters employed in the vicinity of
the wellhead, and is not easily moved to accommodate exchange of equipment
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at the wellhead. In addition, this type of scaffolding is accessed by ladders
which represent an additional safety hazard.
U.S. Patent 6,681,894 discloses a portable wellhead platform that
provides access of personnel to the wellhead during workover and snubbing
operations which is coupled directly to the wellhead with a pipe flange
adaptor.
U.S. Patent 6,848,539 also discloses a demountable wellhead platform
that is supported above the wellhead by an armature connected to a blow-out
preventer stack.
U.S. Patent Application 20070193749 discloses a mobile transport
platform for a snubbing system which has substantially all of the equipment
mounted thereon as required for snubbing operations. The system comprises a
snubbing structure with work platforms pivotally mounted at the rear of an
equipment bed of a truck.
PCT publication W02006019880 discloses a truck mounted, self propelled
unit that includes a self-erecting mast that includes a work platform
supported
in the horizontal position over the wellhead. The work platform is typically
mounted to the rear of the truck.
Thus, prior attempts to provide a convenient work platform for workover
and completion operations at oil and gas wellheads have provided platforms
that are connected to equipment disposed at the wellhead itself, or integrally
connected to a vehicle. There is a need for a more flexible and inexpensive
workover platform that allows convenient access to the wellhead for exchange
or repair of equipment disposed thereon. The present invention satisfies this
need, among others.
SUMMARY OF THE INVENTION
The present invention provides a movable platform system for performing
workover tasks on a wellhead. The system includes a platform base with a base
wellhead access gap at its front end. At least one track is fixed to the upper
surface of the platform base and extends from the rear of the platform base to
a
position near the rearward edge of the wellhead access gap. A platform support
frame with a wellhead access gap at its front end is coupled to the track and
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configured for movement along the length of the track. An upper platform is
connected to the platform support frame and also has a platform wellhead
access gap at its front end. The three wellhead access gaps at the three
levels
of the platform system are substantially aligned when the moveable platform
support frame is disposed and locked in the working position above the
wellhead, so that workers on the upper platform have access to equipment
surrounding the wellhead.
When equipment repair or exchange is necessary at the wellhead, the
platform support frame is unlocked from the track and can be moved rearwardly
along the track to provide free space in the vicinity of the wellhead. The
platform support frame can then also be locked in its rearward position along
the track.
The upper platform can be vertically adjusted and the upper platform is
conveniently modified to include various safety features such as removable or
foldable guard rails, safety tether anchoring posts and stairs extending from
the
upper platform to the ground or to the platform base.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of the platform system according to an
embodiment of the present invention.
FIG. 2 is a top perspective view of the platform base and the platform
support frame according to an embodiment of the present invention.
FIG. 3 is a side view of the platform base and the platform support frame
according to an embodiment of the present invention.
FIG. 4 is a front perspective view of the platform system according to an
embodiment of the present invention, with the upper platform omitted for
clarity.
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FIG. 5 is a rear perspective view of the upper platform according to one
embodiment of the present invention.
DETAILED DESCRIPTION
An embodiment of the movable platform system is shown by way of
example with reference to Figures 1 to 5. The platform system 10 includes as
main components, a platform base 11, a platform support frame 12 which is
moveable with respect to the platform base 11 and an upper platform 13 which
is connected to the platform support frame 12 and moves cooperatively
therewith.
In the embodiment shown, a platform base 11 is constructed with
elongated skid members 14 although other constructions of platform bases are
possible, such as for example, a one-piece flat base. In the illustrated
embodiment, transverse reinforcing members 16 connect the skid members and
may be optionally fitted with reinforced flanges 18. The rear ends of the skid
members may be fitted with platform base wheels 20 whose function is to
facilitate rolling movement of the entire platform system 10 along the ground
or
along a flat surface between the platform and the ground, when the forward
edge 22 of the platform base 11 is lifted and pushed.
In the embodiment shown in the figures, tracks 24 are attached to the
skid members 14. The tracks are each configured to retain ridged wheels 26 in
a manner similar to the way a typical train wheel engages a train track for
secure movement along the track. Other arrangements are also possible, such
as a rack and pinion gear system for example, wherein the rack is disposed
along the surface of the platform base 11.
In the embodiment shown in the figures, the lateral sides of the track 24
are provided with a plurality of transverse holes 28 (best seen in Figure 3),
each configured for insertion of a locking pin (not shown) whose function is
to
prevent unwanted movement of the ridged wheels 26 along the tracks 24. Each
ridged wheel is contained within a housing 30 which holds the axle (not shown)
of the ridged wheel 26. The housing 30 also has at least one transverse hole
31
that can be substantially aligned with any one of the other transverse holes
28
along the track 24. The housing 30 can be locked to a position along the track
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24 by insertion of a locking pin (not shown), through the aligned holes 28,
thereby preventing movement of the ridged wheel along the track 24 as
described previously.
Each housing 30 is connected to a leg 32 that supports one of the four
corners of the platform support frame 12. The entire platform support frame
12 is thereby moveable along the tracks 24. Advantageously, the construction
of the platform support frame 12 is such that one or two workers can push it
along the tracks 24 from the forward working position to a rearward retracted
position to allow for repair or exchange of equipment at the wellhead.
It is notable that all three levels of the platform system 10 each have a
gap that is intended to accommodate the wellhead with its associated
equipment. The platform base 11 has a base wellhead access gap 34 that
remains fixed in position with the fixed position of the platform base 11. The
platform support frame 12 has a support frame wellhead access gap 36 and the
upper platform 13 has an upper platform wellhead access gap 38 which is
substantially aligned with the support frame wellhead access gap 36. Gaps 36
and 38 remain aligned and move cooperatively when the platform support
frame 12 is moved along the tracks 24. It is also notable that the tracks 24
extend into forward portions of the platform base 11 adjacent to the base
wellhead gap 34. This allows the platform support frame 12 and the
cooperating upper platform 13 to be placed in a position above the wellhead so
that workers can carryout workover or completion tasks thereupon.
Returning now to the platform support frame 12, attached generally at
each corner is an upper platform vertical extension means, such as a screw
jack
40 which may be operated through hydraulic power via a sprocket and chain
drive, for example. Instead of screw jacks 40, hydraulic cylinders (not
illustrated) could be used. The platform support frame 12 further has
connection points 42 for insertion of vertically-adjustable extension members
44 which may be each made up of sections that are added after the screw jacks
40 vertically extend the upper platform 13.
The upper platform 13 may be fitted with removable railing sections 46
along its outer edges. Advantageously, one such section is of a size
convenient
for removal and attachment in its place of a set of self-leveling stairs 47
that
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extend to the ground or to the platform base. The railing sections 46 are
inwardly foldable from the upright position to rest upon the surface of the
upper
platform 13. Folding the railing sections 46 may be advantageous for
situations
where the platform system 10 is removed from one wellhead site and
transported to another site.
The upper platform 13 may also be fitted with a foldable post 48 at each
corner. The post is useful for attachment of one or more safety tethers to
prevent workers from injury by falling off the upper platform 13. The foldable
post 48, when in the folded position, rests against the upper surface of the
upper platform 13 again as may be advantageous for situations where the
platform system 10 is removed from one wellhead site and transported to
another site.
The tracks 24 niay be fitted with a conveniently removable outrigger bar
50 attachable at a plurality of locations along the tracks and locked to the
tracks at one or more holes 28 in the tracks 24. The outrigger bar is used to
stabilize the platform for windy conditions and to help stabilize the unit
when it
is fully telescoped. The outrigger would be located at the front end of the
opening just behind the support leg 32 and a turnbuckle would be installed
from
the outrigger to the top of the platform support frame approximate to
connection point 42.
The platform support frame 12 may be additionally fitted at its forward
end with a secondary platform 52 which can be connected by horizontally
adjustable members 54 connected to the platform support frame 11. The
horizontally-adjustable members 52 can be connected to vertically-adjustable
members 56 which are connected at their other ends to the rearward edges of
the secondary platform 50.
The foregoing discussion and description is intended to illustrate the
concepts of the invention with emphasis upon the preferred embodiment or
embodiments. The above description is not exhaustive of all options or
mannerisms for practicing the disclosed principles of the invention, the full
scope of which includes this patent specification as a whole, including the
claims
thereof. The full scope of the invention also includes functional and
mechanical
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equivalents of elements set forth herein, including elements described
explicitly
or by implication as being a means for carrying out of a defined task or end.
