U.S. patent number 3,802,137 [Application Number 05/240,525] was granted by the patent office on 1974-04-09 for offshore well rig.
This patent grant is currently assigned to Gulf Offshore Company. Invention is credited to James Eubank Armstrong.
United States Patent |
3,802,137 |
Armstrong |
April 9, 1974 |
OFFSHORE WELL RIG
Abstract
A portable well rig for mounting on offshore platforms including
a telescoping mast mountable on a base which also has the engine
and drawworks mounted thereon, a drain pan and splash guard on the
base, a pair of longitudinally extending beams with jacks for
moving the base longitudinally of said beams, a pair of transverse
support members, detachable clamps for attaching the support
members to platform floor beams, and jacks for moving the entire
rig laterally along the floor beams.
Inventors: |
Armstrong; James Eubank
(Houston, TX) |
Assignee: |
Gulf Offshore Company (Houston,
TX)
|
Family
ID: |
22906893 |
Appl.
No.: |
05/240,525 |
Filed: |
April 3, 1972 |
Current U.S.
Class: |
52/118; 52/115;
173/151; 175/207 |
Current CPC
Class: |
E21B
21/00 (20130101); E21B 15/003 (20130101) |
Current International
Class: |
E21B
15/00 (20060101); E21B 21/00 (20060101); E21b
015/00 (); E04h 012/34 () |
Field of
Search: |
;173/28,37,23,1
;175/85,8,9 ;52/111,113,115-118,632 ;61/46.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sutherland; Henry C.
Assistant Examiner: Pate, III; William F.
Attorney, Agent or Firm: Conley; Ned L. Robinson; Murray
Rose; David Alan
Claims
I claim:
1. A rig comprising
a lower support structure,
an upper base structure on said support structure,
a mast, drawworks and power source on said base structure,
a plurality of C-clamps holding said base structure to said support
structure, and
solid handrails connected to a drip pan substantially covering the
bottom of said base, whereby spillage can be controlled.
2. A rig for mounting on an offshore platform comprising
a pair of parallel jacking beams, each comprising a plurality of
beams in end-to-end relation,
C-clamp means for fastening said jacking beams to floor beams of
said platform,
a support element resting on each jacking beam, with the outboard
edge of the elements resting on the beams and the inboard portions
extending toward each other,
C-clamp means fastening said support elements to said beams,
a truss beam resting on said support elements,
at least one of said truss beam and said support elements
comprising a container for liquid,
C-clamp means fastening said truss beam to said support elements to
form a truss,
a base member resting on said truss,
C-clamp means fastening said base member to said truss,
a mast, drawworks and power source on said base member,
jacking means connected to said support elements and to said
jacking beams, whereby the truss and the apparatus supported
thereby may be moved horizontally relative to the platform upon
release of the C-clamps fastening the support elements to the
jacking beams and operation of said jacking means,
further jacking means connected to said truss and to said base
member substantially at right angles to the first-mentioned jacking
means, whereby the base member and the apparatus supported thereby
may be moved horizontally relative to the truss upon release of the
C-clamps fastening the base member to the truss and operation of
the further jacking means, and
means on said drawworks for supporting the power source thereon,
said power source being mounted above said drawworks by such
means.
3. A method for assembling a rig on an offshore platform having
parallel, spaced-apart floor beams, comprising
clamping a jacking beam to each floor beam, with each jacking beam
lying on top of and extending longitudinally of a floor beam,
placing a support element on each jacking beam, with each support
element resting on a jacking beam and cantilevered toward the other
support element,
supporting the inboard portions of the support elements with
temporary block means,
clamping the support elements to the jacking beams,
placing a truss beam on the support elements to span the space
between them,
clamping the truss beam to the support elements to form a truss,
and
then removing the temporary blocks.
4. A method as defined by claim 3 and including
connecting a jack between each jacking beam and the support element
resting thereon.
5. A method as defined by claim 4 and including
clamping a base member to the truss, with the truss lying on top of
the truss, and
mounting a mast, drawworks and power source on said base
member.
6. A method as defined by claim 5 and including
connecting a jack between each jacking beam and the support element
resting thereon, and
connecting another jack at right angles to the first jacks between
the base member and the truss.
7. A rig comprising
an adjustable length truss, comprising a plurality of elements held
together by clamping means,
a base member mounted on said truss,
a mast, drawworks and power source mounted on said base member,
and
jacking means connected to said truss and to said base, whereby
said base may be moved horizontally along said truss.
8. A rig as defined by claim 7, and including
jacking beams supporting said truss, and
jacking means connected to said truss and to said jacking beams,
whereby said truss may be moved horizontally along said jacking
beams.
9. A rig comprising
a lower support structure, including an adjustable length truss
comprising at least two spaced-apart support elements and a beam,
and clamping means holding said beam to said support elements,
an upper base structure on said support structure,
a mast, drawworks and power source on said base structure, and
clamping means holding said base structure to said support
structure.
10. A rig as defined by claim 9 and including a horizontal beam
under the outboard edge of each support element, so that said
support elements are cantilevered toward each other.
11. A rig as defined by claim 10 and including jacking means
connected to said support structure and to said base structure,
whereby the base structure and the apparatus thereon may be moved
horizontally relative to said support structure.
12. A rig as defined by claim 11 and including further jacking
means connected to said support structure and to said horizontal
beams at right angles to the first-mentioned jacking means, whereby
said base structure and the apparatus thereon may be moved
horizontally in any direction.
13. A rig comprising
at least two parallel elongate elements, each element being
releasably fastened at each end to a support element,
said support elements being spaced-apart and comprising enclosed
box-type structures suitable for storage of liquids,
each support element resting on its outermost edge on a beam
extending horizontally substantially perpendicularly to said
elongate elements, so that the support elements are cantilevered
toward each other when resting on said beams, and the inner edges
of the support elements are supported by said elongate elements,
and
a mast, drawworks and power source mounted on said elongate
elements.
14. A structure comprising
a pair of spaced-apart, horizontally extending, substantially
parallel elongate beams,
an enclosed, box-type structure suitable for storage of liquids
supported on each beam and having an inner portion extending
laterally therefrom toward the other beam,
at least two elongate structural elements lying on and spanning
said box-type structures,
said structural elements being fastened to said box-type structures
to form a truss, whereby the structural elements are supported by
the box-type structures and the adjacent sides of the box-type
structures are supported by the structural elements, and
a mast, drawworks and power source mounted on said structural
elements.
15. A method for assembling a rig on an offshore platform having at
least two parallel, spaced-apart floor beams, comprising
placing an enclosed box-type structure suitable for the storage of
liquids on each of two floor beams, with each such structure
resting on a floor beam and cantilevered toward the other floor
beam,
supporting the inboard portions of the said structures with
temporary block means,
placing a truss beam on said structures to span the space between
them,
fastening the truss beam to said structures to form a truss, so
that the truss beam supports the inboard portions of said
structures, and
then removing the temporary blocks.
16. A rig comprising
an adjustable length truss, comprising a plurality of parallel
elongate elements releasably clamped on each end to spaced-apart
support elements,
each support element including a beam extending horizontally
substantially perpendicular to said elongate elements, positioned
to support said support elements,
said beams being located at the outermost edges of the support
elements, so that the support elements are cantilevered toward each
other when resting on said beams, and the inner edges of the
support elements are supported by said elongate elements,
a base member mounted on said truss, and
a mast, drawworks and power source mounted on said base member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
Tis invention relates to rigs of the type used for drilling and
working over wells, such as oil wells, and particularly to those
specifically designed for offshore well locations.
2. Description of the Prior Art
Offshore oil wells are often drilled from a stationary platform set
in the water and having a floor 30 to 40 feet above the surface of
the water. Because of the expense of such platforms and drilling
operations, and to facilitate servicing of completed wells, often
several wells, up to 40 or more, are drilled from the same
platform, through holes in the platform floor spaced several feet
apart.
Following completion of the wells it is often necessary to do
"workover" operations on the wells. Such workover operations may
include, for example, replacing down-the-hole equipment, acidizing,
fracturing, and wash-out operations. Such workover operations are
performed with a rig similar to a drilling rig, although it is
usually smaller because it is not required to carry as heavy
weights of pipe. Many workover rigs may also be used for the
drilling of relatively shallow wells.
Such rigs are well known, having been used for many years on land
wells. These rigs are commonly made portable, being carried on the
bed of a truck or a trailer. A number of different companies
manufacture and sell such portable rigs for both workover and
shallow drilling operations. Examples of rigs heretofore used may
be found in the Composite Catalog of Oil Field Equipment and
Services, 1970-71 Edition, at pages 1203 to 1211, 1282, 1283, 1323
to 1338, 1612 to 1615, 1999 to 2019, 2050 to 2062, 3422 to 3427,
4079 to 4082 and 5023 to 5034.
In recent years some of these workover rigs have been adapted for
use on offshore platforms, as shown, for example, at page 2018 of
the aforesaid Composite Catalog. However, it has been found that
such rigs are not readily adaptable to offshore platform
operations. In the first place, when used on land portability from
one well to the other was readily accomplished due to the fact that
the rigs are mounted on trucks or trailers. However, this is not
feasible in offshore operations, where the rig must be moved from
one platform to another, and where, after installation on a
platform, it must be moved a number of times to service all of the
wells on the platform. The land based rigs may weigh 100,000 pounds
or more. In order to move such a unit to an offshore platform it
must be dis-assembled into smaller components and then reassembled
on the platform. Another problem encountered on offshore platforms
is the limited amount of space available for the workover rig. Land
based rigs are seldom compact enough to be moved to all the
positions necessary to service all of the wells on a platform.
SUMMARY OF THE INVENTION
The invention comprises a rig, primarily for use as a workover rig,
which is particularly adapted to solve the problems heretofore
encountered in operations on off-shore platforms. Preferably the
rig has adjustable supports allowing mounting directly on the floor
beams of the platform, and means for readily moving the mast and
rotary table of the rig to line up with a plurality of wells served
by the platform. In the preferred embodiment, the rig is assembled
on the platform from a plurality of relatively light weight units,
so that transfer of the rig to and from the platform, and assembly
on the platform, can be accomplished without the need for any
lifting equipment except the platform crane. Preferably many of the
units are clamped together, for versatility in positioning with
respect to each other, thereby avoising the necessity of
time-consuming operations formerly needed to fit various units at
desired locations. Compactness is preferably achieved by utilizing
structural elements as storage tanks, and by mounting some units on
top of others.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a plan view of an offshore platform showing one
embodiment of a rig in accordance with this invention thereon;
FIG. 2 is an elevational view of the embodiment of the rig shown in
FIG. 1, taken at line 2--2 of FIG. 1;
FIG. 3 is another elevational view of the embodiment of the rig
shown in FIG. 1 of the drawing, taken at line 3--3 of FIG. 1;
FIG. 4 is an elevational view of one embodiment of a mast which may
form a part of the rig of this invention;
FIG. 5 is a plan view of the embodiment of the mast shown in FIG.
4, with the mast sections shown nested; and
FIG. 6 is a plan view of a cargo vessel, showing how one embodiment
of the rig of this invention may be carried on a vessel, together
with other equipment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an offshore platform having equipment thereon such as
may be required for workover operations. One embodiment of a rig in
accordance with this invention is depicted at 12. The platform may
also support the tool pusher's quarters 14, a platform crane 16, a
hydraulic accumulator 18, generators, air compressors, and other
utility equipment at 20, and high pressure pumps and tanks 22 and
24. A pipe rack 26 may be mounted on either side of the rig.
As shown in the drawing, the rig is positioned with its rotary
table 28 positioned over one of a plurality of oil wells 30. Each
oil well has a christmas tree (not shown) mounted below the
platform surface shown in FIG. 1. The rig rests upon platform floor
beams 32 and 34 which extend the full length of the platform. In
the design of offshore platforms such beams are provided with
sufficient strength to support heavy equipment which must be
mounted on the platform during drilling, production and workover of
the wells. These beams may be as close together as 30 feet,
normally where no more than one row of wells is drilled between the
beams, up to 45 feet apart, where, for example, three rows of wells
are drilled, as shown in FIG. 1.
As best seen in FIG. 2, the rig rests upon the platform beams 32
and 34, being supported thereon through the jacking beams 36 and 38
which may constitute steel channels or I-beams extending laterally
of the ends of the rig and clamped to the platform floor beams by
means of C-clamps 40. As shown in FIG. 3, three of the jacking
beams are preferably laid end-to-end on each platform beam.
Structural truss members 42 and 44 rest upon the beams 38 and 36
respectively and may be secured thereto by clamps (not shown)
similar to clamps 40. The support members 42 and 44 are preferably
enclosed box type structures which may be used for storage of water
or drilling mud. The support members include upper horizontal beams
46 and brace members 48 to provide support for other equipment to
be described. A conventional shale shaker 49 may be mounted on the
member 42.
Hydraulic jacks 41 are mounted on the beams 36 and 38, being
connected to the beams and arranged to push against the members 42
and 44.
A pair of "strongback" beams 50 are mounted on the beams 46,
extending longitudinally thereof, and being clamped thereto by
C-clamps 52, the members 42, 44 and 50 forming a truss to support
other equipment, as hereinafter described. The strongbacks are
preferably made of I-beams or other structural members, boxed in to
form tanks which may be used as fuel tanks for the engines.
The space between the elements 42 and 44, and beneath the
strongbacks 50, provides clearance space for blowout preventers
which will be required for working on the wells.
A base member 54 resting on the strongbacks 50 comprises beams 56
extending longitudinally of the strongbacks, being clamped thereto
by means of C-clamps 58. At least two hydraulic cylinders or jacks
55 are mounted on the strongbacks 50 with their rods connected to
the base member 54. More than one connection location may be
provided on the base and the strongbacks to move the base to
various positions relative to the strongbacks, as will hereinafter
be explained.
The base 54 comprises a base member for the tool house 60, the mast
62, and the drawworks 64. To conserve space on this base, the winch
66 is mounted on top of the tool house, and the engines 68 which
provide power to the drawworks are mounted on top of the drawworks.
Stairways 70 and 72 are provided for access to the floor of the
base. A hand rail 74 preferably made of sheet metal, not only
provides a safety device, but is connected to the pan 76, best seen
in FIG. 3, which substantially covers the bottom of the base, to
provide a catch basin to catch spilled liquids, such as mud, oil
and other liquids which might contaminate surrounding waters. The
pan 76 preferably extends the full length of the base 54 and is
closed at both ends for this purpose.
In the embodiment of the invention shown in the drawing the mast is
made in three sections, a lower section 80, a center section 82 and
a crown section 84. Each section is U-shaped in cross-section, and
the sections are tapered slightly, so that the base of the U is
narrower than the distance between the legs of the U at their
extremities, thereby facilitating nesting of one section within the
other, as shown in FIG. 5.
The lower section of the mast comprises four legs 86 joined
together by cross members 88 and 90 and including angular braces
92. As shown in the drawing, FIGS. 3 and 4, the middle section 82
is telescoped within the lower section 80, being overlapped a short
distance for increased strength and rigidity. The crown section 84
is telescoped within the middle section 82 and is also overlapped
therewith. The middle and crown sections are of structures similar
to the lower section, except that a platform 94 is provided at the
top of the crown section for mounting the crown block 96. Also a
tubing board 98 is mounted on the open side of the middle section
and supported at its outer edge by a cable 100 extending upwardly
to the top of the crown section. A drilling line anchor 101, as
well known in the art, may be mounted on the lower section of the
mast.
Elevation of the middle section is accomplished by means of
hydraulic cylinders 102 which extend to the base member 54, and
elevation of the crown section is accomplished by means of the
hydraulic cylinder 104 which is mounted on the lower end of the
middle section and extends upwardly with its rod engaging the upper
end of the crown section. After the sections are elevated to
position and bolted in place, the rods of the hydraulic cylinders
may be disconnected from the extended sections of the mast and
retracted within the cylinders.
The rig of this invention is particularly well suited for transport
to and erection on offshore locations. As shown in FIG. 6, all of
the equipment required for the workover operation may be shipped on
a 145-foot cargo vessel, whereas offshore workover rigs heretofore
available had to be shipped on a barge. The rig may be shipped
broken down into relatively small units, and preferably is broken
down into units weighting not more than 15,000 pounds each, so that
the rig units are readily hoisted onto the offshore platform by
means of the platform crane 16 which is normally available.
Previously, because of the heavy weight of elements of such rigs,
it has been necessary to provide an additional heavy duty crane or
other special facilities to place the rig onto and remove the rig
from the platform.
When the cargo vessel reaches the platform on which the rig is to
be installed, the individual elements are lifted onto the platform
by means of the platform crane 16. The jacking beams 36, 38 are
then laid along the platform beams 32 and 34, respectively, in such
a position that the well to be worked on is positioned between the
beams 36 and the beams 38. These jacking beams are then clamped to
the platform beams by means of the C-clamps 40.
The tanks 42 and 44, which, it will be recalled, constitute truss
members, are then placed on the jacking beams 36, 58, as shown in
FIG. 2, with the inner edges of the tanks supported by temporary
blocks in substantially level position. The tanks are then clamped
to the jacking beams. The strongbacks 50 are then placed on the
tanks 42, 44, spanning them and lying along the beams 46, as seen
in FIG. 2, and the C-clamps 52 are applied to secure the
strongbacks in position. The temporary blocks under the tanks 42
and 44 may now be removed.
The base 54 is then placed on the strongbacks, in such a position
that the rotary table will be substantially directly over the
opening 110 in the platform which provides access to the well which
is to be worked. The base is then clamped to the strongbacks in
this position, by means of the C-clamps 58. The tool house,
drawworks and engine may then be placed on the base, and clamped or
bolted into position. Preferably the drawworks is made in at least
two parts so that it can be lifted by the relatively low capacity
platform crane, and the engines are hoisted separately from the
drawworks and placed on top of the drawworks.
The rotary table is also placed on the base, and the lower section
of the mast hoisted into place and connected at its lower end to
the base. The middle section and crown section of the mast are then
nested inside of the lower section, the hydraulic cylinders 102 and
104 are connected, and the middle and crown sections of the mast
are then elevated by means of the hydraulic cylinders. When these
sections have reached their positions, they are bolted or pinned in
place, and the hydraulic cylinders may then be disconnected and
retracted. Other equipment, such as the stairways and the pipe
racks may then be put in place, various hoses and other lines run,
and the rig is ready for operation.
After completion of operations upon one well, the rig is readily
moved to another well. For example, looking at FIG. 2, in order to
move from the well below opening 110 to the well below opening 112,
the C-clamps 58 which hold the base to the strongbacks 50 are
removed, and the jacking mechanism within the base which is
connected to the strongbacks is operated to slide the base
longitudinally of the strongbacks to reach the desired position.
The C-clamps are then reapplied to hold the rig in this
position.
To move the rig laterally, i.e. longitudinally of the platform as
shown in FIG. 1, the C-clamps holding the tanks 42 and 44 to the
jacking beams 36 and 38 are removed, and the hydraulic jacks 41 are
operated to move the entire rig along the jacking beams 36 and 38.
As shown, the jacking beams 36 and 38 are preferably each made in
three sections so that when the rig has been moved a distance equal
to the length of one section, that section may be picked up and
moved over to the other side of the rig to prepare a further skid
on which the rig may be moved. When the rig has been moved the
desired distance, beams 36 and 38 are again clamped to the tanks 42
and 44.
It will be apparent that the use of C-clamps to hold the various
elements in place is highly advantageous, because it is not
necessary to accurately position every unit in order to line up
bolt holes, or to burn or drill new holes every time the rig is
moved. The C-clamps may be of any suitable design and structure
having sufficient strength to accomplish their purpose. The primary
requirement is that a movable fastener be used which does not
require modification of the structures it is holding when the
fastener is moved from one location to another.
The novelty and superiority of the rig of this invention become
most apparent upon a consideration of the time saved by the use of
this rig as opposed to rigs previously available. In many
instances, the present rig can be disassembled, removed from a
platform, shipped to another platform, and reassembled on the other
platform in 24 hours. Previously it has taken from 3 days to a week
to accomplish such a move.
Furthermore, the novel structure of the rig of this invention
allows it to be readily moved from one well to another on the
platform. The rig base and support structure can even be set at an
acute angle to the platform floor beams, while still being
supported by the beams and being clamped rigidly in place, if this
is necessary because of the positioning of other equipment on the
platform.
The use of structural members as tanks, and the placement of the
engines on top of the drawworks makes the rig unusually compact, so
that it takes up much less platform space than rigs heretofore
used. The entire rig may occupy a space on the platform as little
as 12 feet wide and 30 feet long. In addition, since the rig is
readily broken down into comparatively small units, transporting
between platforms is facilitated.
The rig of this ivention is readily adjustable to various spacings
of platform floor beams. For example, the jacking beams 36, 38 may
be spaced to lie on floor beams 45 feet apart when positioned as
shown in FIG. 2. If the floor beams are closer together, down to 30
feet, the members 42, 44 and the jacking beams are placed closer
together. At 30 feet spacing, the strongbacks may cover the entire
span. No modification of any structure is required for different
floor beam spacings. Thus, the elements 42, 44 and 50 form an
adjustable length truss.
Although preferred embodiments of the invention have been shown and
described, the invention is not limited to these embodiments, since
many variations thereof within the scope of the invention will be
apparent to those skilled in the art. Thus the limits of the
invention are those defined by the claims.
* * * * *