Note: Descriptions are shown in the official language in which they were submitted.
CA 02508559 2005-05-27
WELLHEAD SHELTER
Field of the Invention
The present invention relates to a spill containment device for wellheads.
Background of the Invention
Although care is taken at wellhead sites to minimize spills onto the
surrounding soil,
spills or leaks of well fluids may sometimes occur. Due to the high cost of
site
decontamination, it is desirable to provide a catch pan for collecting spills.
While some previous pans have been proposed, they often have limitations that
restrict
their acceptance by the industry.
Summary of the Invention
A wellhead shelter has been invented that may be used to contain various kinds
of
wellhead spills and leaks and may be formed with consideration as to the
structure of, and
the space limitations about, wellhead structures.
In accordance with one broad aspect of the present invention, there is
provided a
wellhead shelter comprising: a catch pan including at least two sections
defining
therebetween an opening, the opening being positionable about the wellhead
when the at
least two pan sections are secured together; and an upwardly extending cover
including at
least two members each being connectable adjacent their lower ends to the pan
and
connectable together for covering at least a part of the wellhead.
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It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein
various embodiments of the invention are shown and described by way of
illustration. As
will be realized, the invention is capable for other and different embodiments
and its
several details are capable of modification in various other respects, all
without departing
from the spirit and scope of the present invention. Accordingly the drawings
and detailed
description are to be regarded as illustrative in nature and not as
restrictive.
Brief Description of the Drawings
Referring to the drawings wherein like reference numerals indicate similar
parts
throughout the several views, several aspects of the present invention are
illustrated by
way of example, and not by way of limitation, in detail in the figures,
wherein:
Figure 1 is a schematic end elevation of a wellhead shelter.
Figure 2 is a schematic top plan view of a containment pan for a wellhead
shelter.
Figure 3 is a schematic side elevation of a wellhead shelter.
Figure 4 is a schematic side elevation of a wellhead shelter.
Figure 5 is a schematic vertical section through a wellhead shelter.
Figure 6 is a perspective view of another wellhead shelter in a closed
configuration.
Figure 7 is a perspective view of the wellhead shelter of Figure 6 in a opened
configuration.
Figure 8 is an exploded view of the wellhead shelter of Figure 6.
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Detailed Description
The detailed description set forth below in connection with the appended
drawings is
intended as a description of various embodiments of the present invention and
is not
intended to represent the only embodiments contemplated by the inventor. The
detailed
description includes specific details for the purpose of providing a
comprehensive
understanding of the present invention. However, it will be apparent to those
skilled in
the art that the present invention may be practiced without these specific
details.
Referring to Figures 1 to 4, various embodiments of a wellhead shelter 10 are
shown. A
wellhead shelter may be useful for mounting about a wellhead structure 12 for
containing
spilled or leaked liquids from the wellhead to thereby prevent or minimize
environmental
contamination.
Shelter 10 includes a containment pan 14 and an upwardly extending cover 16
that may
each be sized and configured to fit around at least a portion of a wellhead.
Pan 14 may include at least two sections 14a, 14b defining therebetween an
opening 18,
which opening is capable of being disposed about the wellhead when the pan
sections are
secured together so that the pan can be set about the base of the wellhead
with the
wellhead structure extending upwardly therethrough. Sections 14a, 14b can be
secured at
their interface as by use of bonding, such as with welding, durable adhesives,
etc. or
fasteners such as bolts, clamps, etc. For example, the pan sections can each
include an
indentation 14c in their side wall intended for interfacing with the other pan
section
which, when the sections are brought together, form an opening at the
interface. In the
illustrated embodiment, the indentations are semi-circular and together form a
circular
opening at the interface. However, other configurations may be useful, for
example, as
later described.
Each of the sections of the pan includes liquid tight sidewalls and a liquid
tight floor
therebetween. Grating 15 can be supported in the pan at a position spaced from
the floor.
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The pan sections can be double walled at least over a portion of the sidewalls
and floor to
provide for secondary containment.
Upwardly extending cover 16 includes at least two members that are connectable
at their
lower ends 20 to pan 14 and may be brought together and connected in various
ways for
covering, at least partially, the wellhead. Cover 16 may be connectable in
various ways
to pan 14. For example, cover 16 may be detachable or permanently attached to
pan as
by use of joints, hinges, pivots, fasteners, interlock, clamps, etc. In one
embodiment, the
members of cover 16 may each be attached by hinged connections 22 or other
pivotal
connections to the pan such that the members may be pivoted into and out of
position
about the wellhead. In this illustrated embodiment, hinged connections are
positioned
inside the cover 16 to protect them from tampering (i.e. to gain unauthorized
access to the
wellhead). Of course, the hinges, if used, can be positioned in other
configurations, as
desired.
Wellhead structures may vary significantly depending on many factors. Some
common
variations occur in the outer diameter (OD) of the wellhead at its base, which
may usually
be the outer wall of the surface casing. Another common variation is in the
structures of
the wellhead including for each the differing drive, piping and control
systems for pump
jack driven oil wells, rotary driven oil wells, water injection wells, water
source wells,
deep gas wells, shallow gas wells, etc. It is desirable that at least some of
these variations
be addressed in the present wellhead shelter to facilitate a good fit about
the wellhead.
With respect to the varying OD of the wellhead, the sections 14a, 14b, for
example at
their indentations 14c, can be formed to follow or conform to any particular
OD.
However, to facilitate manufacture and installation at least one sizing ring
23 may be
provided to assure that the cylindrical opening and wellhead mate in a leak
resistant or
leak proof fashion, as for example by filling any gap therebetween. As such,
the pan
sections could be more readily produced to form a cylindrical opening with a
diameter
that is large enough to fit about any well head OD, with the actual sizing
being
accomplished by use of sizing ring 23. Sizing ring 23 can be formed in
sections or can be
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flexible to facilitate positioning around the wellhead. The sizing ring may
include a
sealing material 24, such as an elastomer that creates a seal against the
surfaces of the pan
sections and/or the well head so that a liquid resistant or liquid tight seal
is provided
between the parts.
The wellhead in its simplest form is a pipe sticking up from the ground.
However, a
wellhead may often include a main vertical structure 28, a flow tee or line 30
extending
away from the main vertical structure and an upper connection 32 to an
external system
such as a drive or control system. Shelter 10 may cover at least a part of the
wellhead
and may allow for extension of wellhead lines or connections beyond the
confines of the
shelter. For example, in some wellhead configurations, it may be necessary
that parts of
the wellhead extend out from the shelter including, for example, drive units
or pump
jacks extending out above the shelter or flow lines passing through the sides
of the
covering. These openings can include seals between the shelter material and
the
wellhead part. In one embodiment, openings 34 may be provided through the pan
or the
upwardly extending cover to permit extension of parts such as flow tee or line
30
extending away from the main vertical structure and upper connection 32 to an
external
system. In such an embodiment, openings 34 may include seals 36 thereabout to
seal
against fluid passage into or out of the shelter. Such seals can be for
example
compressible, elastomeric materials. In one embodiment, openings 34 are
conveniently
formed at the interface between the members of the cover. For example, notches
can be
formed on the edges of the members and hinged connections 22 can be positioned
so that
when the members fold up toward each other, the notches align to form an
opening. The
hinges and the notches can be positioned to form the opening around a member
extending
from the wellhead.
The components on a wellhead site are often positioned in a known way. The
shelter can
therefore, be constructed to fit about a wellhead. In one embodiment, for
example, the
shelter is sized to fit about a wellhead between the adjacent components, to
cover but
permit extension therefrom of flow lines, etc. and to permit access by a
vehicle to the
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wellhead. For example, the pan may be sized to fit between the well site
components
such as pump jacks, drives, etc. The plan dimensions can be selected to allow
positioning
about the components, while the pan depth can be selected to ensure adequate
catch
volume in the pan. In one embodiment, for example, for a wellhead with a pump
jack,
the pan may be about 50 inches wide being narrower (about 15 inches) on the
pump jack
side PJS. The length can be varied to extend out below the wellhead
components. For
example in one embodiment, the pan may extend out about 30 inches on the
pressure
gauge side PGS. In one embodiment for a shallow gas well, the flow line side
FLS may
extend out 30 inches. In another embodiment for an oil well, flow line side
FLS may be
about 72 inches. Of course, these sizes are only provided as examples of
possible
shelters and should not be considered limiting.
A further embodiment of a shelter is shown in Figure 5. The shelter 10
includes a pan 14
and an upwardly extending cover 16.
Pan 14 includes a plurality of sections that can be brought together to
encircle a wellhead.
The sections each include an outer shell 40 and an inner liner 42. In the
illustrated
embodiment, the inner liner is separable from the outer shell, but inner liner
42 could be
permanently attached to the shell, as by application such as dipping,
spraying, painting.
Pan 14 may be sized to contain leaked fluids. It may be useful to form the pan
to contain
a significant leak, such as at least 1/2, 1 or more barrels of liquid. There
may be a liquid
level detector 43 mounted in the pan to monitor liquid levels. The liquid
level detector
could be connected into a controller for the well, such that the well is shut
down should
the detector sense a high liquid level. Alternately, the liquid level detector
may be
connected to an alarm system that alerts an operator of a problematic liquid
level in the
pan. The liquid level detector 43 may be spaced down from the top edge/maximum
fill
capacity of the pan to provide room for continued leakage containment after
alarm or shut
down.
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The upwardly extending covering includes two clam shell type members 19, each
member being hingedly connected at it lower end to the pan and formed to be
foldable up
towards each other to fully or partially cover the wellhead. The lower ends of
the walls
are formed with U-shaped channels 44 such that they nest down over the upper
wall
edges 45 of the pan to shield the gap between the pan and the upper covering
such that
liquids (rain from outside, spraying liquids from inside, etc.) will run down
and drip off
the walls without passing through the interface. The nesting action of
channels 44 on
upper edges 45 acts to secure the members 19 over the pan through an elongate
interlocking joint and to permit pivotally and/or detachably removing the
members from
over the pan. Latches and/or locks may be provided to further secure the
members to the
pan, if desired. The interfacing edges 48 of the clamshell members can also be
formed to
overlap, or nest together in a U-shaped member, to seal against passage of
liquids
therethrough.
A releasable lock 50 may be provided to fix members 19 in the upwardly
covering
position.
Insulative material 52 can be applied to members 19 of the covering to assist
with the
retention of heat within the enclosure. The insulative material may be coated
to protect it
against abrasion and chemical degradation. If desired, a solar powered,
explosion proof
heater 54 can be provided on the shelter to heat the interior.
A further embodiment of a shelter is shown in Figures 6 to 8. This
particularly illustrated
shelter is formed to accommodate a wellhead on a shallow gas well. The shelter
10
includes a pan 14 and an upwardly extending cover 16.
Pan 14 includes a plurality of sections 14a, 14b including interfacing
indentions 14c that
can be brought together to encircle wellhead vertical members. Flanges 56
extend at the
interfacing sides to accept fasteners 58 for connecting the pan sections
together.
Channels 60 can be positioned over the interfacing sides after connecting them
to shield
the interface against contact with and passage therethrough of liquids. The
indentations
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14c are enlarged and positioned to fit about many possible configurations of
main vertical
wellhead components associated with a shallow gas well. Two-part sizing rings
23 are
installable to seal between the actual wellhead component and indentations
14c, A
variety of sizing rings may be available to accommodate various wellhead
component
ODs. Sizing rings 23 are formed with flanges for accepting fasteners to secure
the two
parts of the ring together. Sizing rings 23 can include downwardly extending
walls 62
that extend over the indentation's upper edges to urge any liquids that drop
on sizing rings
to run off into the pan. Seals (not shown) may be provided between the sizing
rings and
the parts against which they abut. Grating 15 may be supported in the pan by
ledges 15a.
If desired, the shelter may be used to protect other wellsite components. In
this
illustrated embodiment for example, pan 14 supports a methanol sphere stand
63.
Cover 16 in this embodiment, although having a clam-shell-type operation,
resembles a
typical shed. Cover 16 includes a pair of members 64 each attached to pan 14
by hinges
22. Hinges 22 include a removable hinge pin 66 to facilitate assembly. Hinges
22, as
formed, permit the members 64 to be laid down on either side of the pan for
full access to
the wellhead within the shelter, without removing or disassembling the pan,
which may
contain liquids.
Members 64 includes an inner wall surfaces 68 and an outer wall surfaces 70
with
insulation (cannot be seen) disposed therebetween. Wall surfaces 68, 70 are
connected
and supported on frame members 72. The wall surfaces and frame members form
extensions as at 74, 76, 78 to provide overlaps at the interfacing edges
between the
members 64 and between members 64 and pan 14 to shield against the passage of
liquids
into and/or out of the shelter, The members of the cover can also, or
alternately,
overhang the pan to cause liquids that land on the cover's outer surface (i.e.
precipitation)
from running into the pan.
Latches 50a are mounted on members 64 to accept a padlock or other locking
mechanism.
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An inspection door 80 and opening (behind the door) may be provided to permit
observation of the wellhead without opening members 64. Door 80 may include a
latch
82 to accept a lock, if desired.
A wellhead shelter according to one of the various embodiments may be
installed on new
or existing wellheads. To install the shelter, the pan sections can be placed
on ground
surface or dug into the ground. The sections are brought in around the
wellhead and
secured together, as by bolting, such that the pan surrounds the wellhead.
Rings/seals are
used to seal the pan about the wellhead.
The covering members and pan may then be connected, for example, by inserting
hinge
pins into hinge journals or nesting the covering members over the pan edges.
The
covering members may then be folded up over the wellhead and releasably locked
together.
Should it be necessary to gain access to the wellhead, the lock can be
released and the
covering members folded down to rest on the ground surface or adjacent lease
components. If an inspection opening is provided, it may be desirable first to
open the
inspection door prior to removing the covering members. Use of the inspection
door may
be beneficial to briefly inspect the wellhead without removing the entire
covering or
where a hazardous gas may have built up within the shelter, which may be quite
harmful
if released freely by opening the covering.
The shelter can be formed of various materials. Materials may be selected for
durability,
construction, resistance to petroleum well fluids, handling etc. Containment
may be
facilitated by materials that resist deterioration due to contact with
wellbore fluids and
can withstand continued and long-term exposure outside. In one embodiment, the
main
shelter parts may, for example, be formed of steel, coated steel, fiberglass,
polymeric
materials, or combinations thereof.
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The previous description of the disclosed embodiments is provided to enable
any person
skilled in the art to make or use the present invention. Various modifications
to those
embodiments will be readily apparent to those skilled in the art, and the
generic
principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
consistent
with the claims, wherein reference to an element in the singular, such as by
use of the
article "a" or "an" is not intended to mean "one and only one" unless
specifically so
stated, but rather "one or more". All structural and functional equivalents to
the elements
of the various embodiments described throughout the disclosure that are know
or later
come to be known to those of ordinary skill in the art are intended to be
encompassed by
the elements of the claims. Moreover, nothing disclosed herein is intended to
be
dedicated to the public regardless of whether such disclosure is explicitly
recited in the
claims.
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