U.S. patent application number 14/060374 was filed with the patent office on 2014-02-13 for mobile hydraulic workover rig.
This patent application is currently assigned to Rodgers Technology, LLC. The applicant listed for this patent is Rodgers Technology, LLC. Invention is credited to Troy A. Rodgers.
Application Number | 20140041855 14/060374 |
Document ID | / |
Family ID | 41255820 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140041855 |
Kind Code |
A1 |
Rodgers; Troy A. |
February 13, 2014 |
MOBILE HYDRAULIC WORKOVER RIG
Abstract
A rig including a base structure, a derrick extending from the
base structure, a hydraulic lift cylinder connected to the upper
end of the derrick, a lower slip assembly connected to the base
structure, an upper slip assembly, and at least two snub cylinders
connected to the base and the upper slip assembly. A distal end of
a piston rod of the lift cylinder is connectable to a pipe string
extendable through the upper and lower slip assemblies such that
both a lifting force and a snubbing force may be applied
simultaneously to the pipe string.
Inventors: |
Rodgers; Troy A.;
(Chickasha, OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rodgers Technology, LLC |
Chickasha |
OK |
US |
|
|
Assignee: |
Rodgers Technology, LLC
Chickasha
OK
|
Family ID: |
41255820 |
Appl. No.: |
14/060374 |
Filed: |
October 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13451330 |
Apr 19, 2012 |
8561685 |
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14060374 |
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12370393 |
Feb 12, 2009 |
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13451330 |
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61126011 |
Apr 30, 2008 |
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Current U.S.
Class: |
166/85.1 |
Current CPC
Class: |
E21B 15/003 20130101;
E21B 19/00 20130101 |
Class at
Publication: |
166/85.1 |
International
Class: |
E21B 19/00 20060101
E21B019/00 |
Claims
1. A rig for raising and lowering a pipe string, comprising: a base
structure; a derrick extending from the base structure and having
an upper end; and a single hydraulic lift cylinder including a
cylinder and a piston rod, the cylinder having an upper end and a
lower end, and the rod having a proximal end and a distal end, the
lower end of the cylinder being fixed to the upper end of the
derrick and the rod extending downwardly from the lower end of the
cylinder and movable between a retracted condition and an extended
condition, wherein the piston rod of the lift cylinder is axially
aligned with the pipe string when the piston rod is connected to
the pipe string.
2. The rig of claim 1, wherein the base structure includes a first
row of storage containers and a second row of storage container
arranged in a parallel, spaced relationship to the first row of
storage containers.
3. The rig of claim 2, wherein each of the storage containers has a
rectangular configuration, wherein the storage containers of the
first row of storage containers are arranged in an end-to-end
relationship, and wherein the storage containers of the second row
of storage containers are arranged in an end-to-end
relationship.
4. The rig of claim 2, wherein the first row of storage containers
is slidably mounted on a first skid, and wherein the second row of
storage containers is slidably mounted on a second skid.
5. The rig of claim 2, wherein the base structure further comprises
a work platform mounted on the storage containers, and wherein the
derrick includes a base member mounted on the work platform
centrally between the first row of containers and the second row of
containers.
6. The rig of claim 5, wherein the derrick is supported by the base
member, and wherein the base member is movable relative to the work
platform.
7. The rig of claim 6, wherein the first row of storage containers
is slidably mounted on a first skid, and wherein the second row of
storage containers is slidably mounted on a second skid.
8. The rig of claim 1, wherein the derrick has an open side
extending from an upper end to a lower end thereof.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/451,330, filed Apr. 19, 2012, now U.S. Pat.
No. 8,561,685, which is a continuation of U.S. patent application
Ser. No. 12/370,393, filed Feb. 12, 2009, which claims priority to
Provisional Patent Application No. 61/126,011, filed Apr. 30, 2008,
each of which are hereby incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] The following relates to workover and drilling rigs, and
more particularly relates to a novel and improved method and
apparatus adaptable for use in the servicing and treatment of oil
or gas wells.
[0003] An important consideration in the design and construction of
workover rigs in the servicing and treatment of wells is the
ability to move efficiently between wells which are located a short
distance from one another, such as, for example, wells in a cluster
or in one or more rows in directional drilling operations.
[0004] In the past, workover rigs have been so constructed and
arranged that the derrick and its substructure must be disassembled
to move between each well. It has also been proposed to utilize
skids without disassembling the structure but has required some
disassembly of the derrick and is undesirable from a number of
standpoints including but not limited to the time and cost of
installation each time that the rig has to be moved; and in the
past such installation has involved the utilization of cables or
guidewires anchored in the ground to stabilize the derrick.
[0005] Accordingly, there is a need for a portable workover rig
which does not require cables or guidewires to support or anchor
the derrick and to provide for a derrick and substructure which is
completely hydraulic and can be advanced on skids between wellheads
without pivoting or disassembling the derrick or other parts of the
rig and can be utilized on land as well as off-shore. Further, it
is desirable to construct the derrick in such a way as to
facilitate mechanical side-loading and unloading of pipe from and
to raised pipe rack sections at the base of the derrick without
necessity of threading or loading manually upward and downward
through the base of the derrick.
SUMMARY
[0006] It is therefore an object to provide for a novel and
improved rig which is conformable for use in servicing wells which
are located on land or offshore in a reliable and efficient
manner.
[0007] Another object is to provide for a novel and improved
portable workover rig which is completely fluid-actuated, is
extremely stable and does not require the use of guidewires or
cables to anchor to the ground.
[0008] A further object is to provide for a novel and improved
workover rig which includes a hollow base structure containing the
necessary pumps and reservoirs for hydraulic actuation while at the
same time greatly stabilizing the entire structure; and further
wherein the entire rig including the derrick and base structure can
be advanced between wells without disassembly of any of the rig
structure.
[0009] Still another object and feature is to provide for a novel
and improved derrick which is mounted on a hollow base structure
and facilitates assembly and disassembly of the pipe sections to be
lowered into or lifted out of the well with a minimum of labor and
equipment required.
[0010] The above and other advantages and features will become more
readily appreciated and understood from a consideration of the
following detailed description of different embodiments when take
together with the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of one embodiment of workover
rig;
[0012] FIG. 2 is a perspective view of the top section of the
derrick;
[0013] FIG. 3 is a perspective view of the middle section of the
derrick;
[0014] FIG. 4 is a perspective view of the base section of the
derrick;
[0015] FIG. 5 is a perspective view of the guideways and base
support containers on opposite sides of a series of wellheads;
[0016] FIG. 6 is an elevational view of the base support structure
shown in FIG. 5;
[0017] FIG. 7 is a view in more detail of one of the guideways with
the hydraulically activated pusher for advancing the base structure
along a guideway;
[0018] FIG. 8 is a plan view of the base support structure for the
rig;
[0019] FIG. 9 is a fragmentary perspective view of the pair of the
guideways on one side of the base support structure;
[0020] FIG. 10 is an end view of one of the corner supports used
for advancing the base structure along the guideways;
[0021] FIG. 11 is a perspective view of the entire work floor
mounted on the base structure;
[0022] FIG. 12 is an exploded view of the base of the derrick at
one end of the derrick slide plate on the work floor;
[0023] FIG. 13 is a perspective view of the work floor in relation
to the base structure;
[0024] FIG. 14 is a somewhat schematic fragmentary view of the
catwalk;
[0025] FIG. 15 is a top plan view in detail of one of the grating
spacers;
[0026] FIG. 16 a plan view in detail of another one of the grating
support spacers;
[0027] FIG. 17 is a top plan view of one of the pipe rack
sections;
[0028] FIG. 18 is an end view of the pipe rack section shown in
FIG. 17;
[0029] FIG. 19 is a side view of one of the pipe racks shown in
FIG. 17 and illustrating a lift bracket for lifting each of the
pipe sections along with a lift stop support;
[0030] FIG. 20 is a somewhat diagrammatic view of the main lift
cylinder;
[0031] FIG. 21 is a schematic view of the control panel and
valves;
[0032] FIG. 22 is another schematic view of the pressure gauges
associated with the hydraulic control system;
[0033] FIG. 23 is a schematic view of an auxiliary control
panel;
[0034] FIG. 24 is a schematic view of the pressure gauges
associated with the auxiliary control panel;
[0035] FIG. 25 is a diagrammatic view of the gearbox and hydraulic
pumps for operation of the hydraulic components; and
[0036] FIG. 26 is a perspective view of an offshore workover
rig.
[0037] FIG. 27 is an elevational view of a portion of the workover
rig of FIG. 26.
DETAILED DESCRIPTION OF FIRST EMBODIMENT
[0038] In a first embodiment, as shown in FIGS. 1 to 25, a workover
rig 10 is broadly comprised of a derrick 12 mounted on a work floor
13 above a base structure made up of one or more housings 14
adapted to be mounted on elongated skids or guideways 16. The
guideways 16 are arranged in pairs to flank one or more rows of
wellheads represented at W in FIGS. 1 and 5. As a setting for the
embodiment shown, the wellheads W may be for gas wells in which
directional drilling has enabled the wellheads W to be spaced very
short distances apart, such as, on the order of 3 to 6 feet.
Fluid-actuated, double-acting cylinders 62 are mounted behind the
base structure housings 14 on each pair of skids 16 for the purpose
of advancing the rig 10 along the row or rows of wellheads W.
Standard snub cylinders, illustrated in FIGS. 26 and 27 and
designated by the reference letter S', are also positioned on the
work floor 13 and hydraulically controlled through a main control
panel to be hereinafter described.
[0039] As best shown in FIG. 12, the derrick 12 supports a main
lift cylinder 20 mounted over a center bore 21 at one end of a work
floor or platform 13, and lateral adjustment cylinders 81 are
engageable with a slidable derrick plate 24 to accurately align the
main lift cylinder 20 on the derrick 12 over the well to be
serviced or completed.
[0040] Referring to FIGS. 2 to 4, the derrick 12 is comprised of a
top section 28 shown in FIG. 2, a middle section 30 shown in FIG.
3, and a bottom or base section 32 shown in FIG. 4. As best seen
from FIG. 1, the sections 28, 30 and 32 are permanently fastened
together in end-to-end relation and each is comprised of generally
U-shaped gusset plates 34 in vertically spaced relation to one
another and joined at opposite edges to vertical tubes 36 having
ladders defined by metal rungs 35 therebetween and inner spaced
vertical tubes 37 on inner side edges of the plates 34. The top
section 28 includes a solid top plate 38 with a notch 40 for
mounting of the upper end of the lift cylinder 20. The intermediate
or middle section 30 is made up of three gusset plates 34 mounted
at spaced intervals between the square tubing 36 and 37, and the
base section 32 has upper and lower spaced gusset plates 42 and 44
with center openings 46 for extension of a piston rod 27 at the
lower end of the lift cylinder 20. When the sections 28, 30 and 32
are joined together, the U-shaped gusset plates 34 are so aligned
as to form an open or recessed front along one side of the
substantial length of the derrick so that the lift cylinder 20 is
accessible for side-loading and stringing standard pipe sections P
together that are to be lowered into the well or subsequently
raised or lifted from the well in a manner to be described. The
base plate 44 of the derrick is mounted on the derrick slide plate
24, as shown in FIG. 13, to enable lateral adjustment of the
derrick 12 by means of the cylinders 22 as earlier described.
[0041] FIGS. 11 to 14 illustrate the work floor 13 in more detail
and its mounting on the base housing containers 14. The derrick
slide plate 24 with a center bore 45, which is shown in exploded
form in FIG. 12, is mounted on main crossbeams 46 which are joined
together at opposite ends by I-beams 47. The derrick slide plate 24
is slidable along the crossbeams 46 on a low-friction insert plate
25 and of a type similar to that to be described with respect to
the skid mount. A generally rectangular catwalk 48 is mounted on
the crossbeams 46 as shown and traverses the entire width of the
work floor 13 in overlying relation to the base housing members 14.
Grating spacer 50 is interposed between the catwalk 48 and pipe
rack sections 51 and 52, and the sections 51 and 52 are joined
together by another grating spacer 54 to support the pipe sections
P which are stacked on the sections 51 and 52.
[0042] FIG. 13 illustrates the catwalk 48 and grating spacer
assembly mounted on the base structure as represented by the
rectangular housing members 14. In addition to the crossbeams 46
referred to earlier, upper beams 49 extend along the entire length
of the base structure and securely anchor the upper work floor 13
hereinabove described to the housing members 14. In the embodiment
herein shown, the housing members 14 are made up of large shipping
containers on the order of 8 feet wide by 20 feet long. As shown in
FIGS. 5 to 10, the shipping containers 14 are of elongated,
rectangular configuration and each pair is mounted in end-to-end
relation to one another with a grade bolt 50 between adjoining ends
of the beams 49 to interconnect each pair of containers 14 into
flush, aligned relation to one another. The skids 16 are firmly
anchored in the ground in spaced parallel relation to one another
and each pair of skids 16 extends beneath the inboard and outboard
undersurfaces of the containers 14, as best seen from FIG. 8.
Further, each pair of skids 16 is rigidly interconnected by
crosstube members 17 at spaced intervals along the entire length of
the skids 16.
[0043] In order to advance the housing members or containers 14
along the skids 16, as shown in FIGS. 6, 7 and 10, low-friction
slide members 58 each include an upper guide plate or rod 59
inserted into a recess 60 in the undersurface of the front and rear
corner of each of the housing members 14 so that the entire weight
of the housing members 14 is applied through the low friction slide
members 58 to the skids 16. Low-friction plastic insert plates 61,
as best seen from FIG. 10, are positioned between each low friction
slide member and skid to enable the entire rig to slide easily
along the guideways or skids 16 with a minimum of friction. A
double-acting cylinder 62 includes a piston rod 63 bearing against
a stop 64 which is adjustably positioned on the skid by an
adjustment bolt 66, and the opposite end of the cylinder 62 is
affixed to a pusher 66 in direct proximity to and behind one of the
low friction slide members 58. The stops 64 are inserted into one
of a series of adjustment openings 65 along the length of each skid
16 and spaced apart a distance corresponding to the maximum length
of extension of the cylinder. When fluid under pressure is applied
in a direction causing extension of the cylinder 62 away from the
stop 64, the housing members 14 will be advanced a distance
corresponding to the axial movement of the cylinder 62, bearing in
mind that the four cylinders 62 will be activated in unison behind
the housing members to advance them along the skids 16. Also, the
housing members 14 will be advanced incrementally by successively
advancing and retracting the cylinders 62 and moving the stops 64
and 66 to the next adjustment opening 65.
[0044] FIGS. 14 to 19 are detailed views of the catwalk 48 and
grating spacers 50 and 54, the grating spacers 50 extending between
the catwalk 48 and a pipe rack section 51. The catwalk, as
illustrated in FIG. 14, is comprised of grating 145 supported on
gusset I-beams 146 between rails 148 extending length-wise on
opposite sides of the catwalk, and the catwalk 48 is positioned
between the crossbeams 46 and the first grating spacer 50. There
are three grating spacers 54 in end-to-end relation to one another
between the pipe rack sections 51 and 52. The grating support
spacers 50 and 54 are correspondingly made up of two-inch square
tubing support members 156 underlying a grate 158 and joined to
angle irons 159 at the four corners of the grate 158.
[0045] The pipe rack sections 51 and 52 shown in FIGS. 17 to 19
overly portions of the catwalk 48 and, as shown in FIGS. 1 and 13,
extend along both sides of the derrick 12 so that the pipe sections
P may extend lengthwise of the catwalks. Both sections
correspondingly include a rectangular grating 161 which is
reinforced by I-beams 172 and square tubes 173 across the
undersurface of the grating 161 as illustrated. Also, a flat plate
174 is mounted on the grating 171, as best seen from FIG. 18; and
FIG. 19 illustrates the pipe lift slot 75 on the lift bracket 76
which is pivotally mounted on the plate 74 on each pipe rack and
controlled by a double-acting cylinder 78 to lift and lower each
length of pipe. One of the I-beams 72 is centered between opposite
sides of each pipe rack section, and a lift stop support 80 extends
upwardly from the plate 74 to limit downward movement of the lift
bracket 76.
[0046] The derrick 12 is mounted at one end of the work floor 13 on
the derrick slide plate 24 with the generally U-shaped open front
side of the derrick 12 facing the pipe racks 51 and 52, and the
cylinder 20 is aligned vertically with respect to the center bore
21 over the wellhead W. Although FIG. 12 illustrates the base 44 of
the derrick in exploded form, it is centered on the derrick slide
plate 24 and has its center opening 45 aligned directly over the
center bore 21. In this way, the derrick 12 will follow the
shifting of the derrick slide plate 24 in aligning the center bore
21 over the wellhead W to be serviced. Specifically, the derrick
slide plate 24 is mounted on low-friction plates 25 and is advanced
by the lateral adjustment cylinders 81 in spaced parallel relation
to one another on the work floor, the end of the cylinders 81 being
anchored by a pair of bolts 82 through a spaced pair of openings in
each cylinder 81 which are aligned with two matching openings 84 in
the derrick slide plate 24. Additional openings 86 are provided in
the derrick slide plate 24 for mounting the base plate 44 of the
derrick 12 by suitable fasteners, not shown. Piston rods 88 at the
opposite ends of the cylinders 81 are anchored by bolts 89 to base
plates 90 so that the cylinders 81 are free to advance and retract
the derrick slide plate 24 and the base plate 44 in a lateral
direction across the end of the work floor 13. Removable stops 91
are insertable into openings 92 which are at staggered intervals
from the side edge of the work floor 13 to shift the path of
movement of the derrick slide plate 24 and the base plate 44 with
respect to the work floor 13 and the ground in vertically aligning
the center bores 21 and 45 over each wellhead W in succession.
[0047] There is shown for the purpose of illustration but not
limitation in FIGS. 20 to 25 a hydraulic control circuit for
operation of the rig and its accessories beginning with one form of
lift cylinder in FIG. 20 and continuing with the various controls
and control panels in FIGS. 21 to 25 forming part of the hydraulic
control circuit. In FIG. 1, the lift cylinder 20 is shown to have
its lower end mounted on the top plate 38 of the derrick 12 with
the piston rod 27 extending downwardly through the notch 40 in the
top plate 38 of the derrick 12. The cylinder 20 is double-acting
with flow lines 93 and 94 extending between a lower directional
control box 95 via lower ports 96 and upper ports 97 into the upper
end of the cylinder. The lower end of the piston rod 27 is notched
at 98 for suspension of a standard, hydraulically-actuated elevator
99, as illustrated in FIG. 1. FIG. 21 schematically illustrates a
flow control valve 101 for the lift cylinder 20, the valve 102 for
a standard rotary table control mounted over of the derrick slide
plate 24 and the base plate 44, and pressure relief valves 104 for
the lift cylinder 20, rotary table, snub cylinders S' and the
conventional upper slips 140 (FIG. 27) and lower slips 141 on the
work basket. A four-bank control represented at 105 operates the
slips 140 and 141 and pusher cylinders 62 on the derrick 12. FIG.
22 merely illustrates the various pressure gauges on the panel as
designated at 106 for the lift cylinder 20, snub cylinders S',
slips and rotary table. In addition, a pump gauge 107 is provided
for the pump from the reservoir and a weight gauge 108 is provided
for sensing the weight of the pipe string.
[0048] FIG. 23 is another schematic of an auxiliary control panel
110 for use by a second operator and includes a three-bank control
112 for the winch and pipe rack bracket 76. Another set of controls
is provided at 114 for the blow-out preventers in the system, and
pressure relief valves are represented at 116 for the blow-out
preventers. FIG. 24 also represents the various pressure gauges 118
for the pipe rack pressure gauge, blow-out preventer pressure
gauge, tong pressure gauge and Hydril pressure gauge.
[0049] FIG. 25 illustrates the engine, gear box and hydraulic pumps
including a dual stage pump 120 to operate the main lift cylinder
20, a three-stage pump 122 for the blow-out preventers, catwalk and
tongs, another dual stage pump 124 for the elevators 99, rotary
drive table and lift cylinder 20, and a dual stage pump 126 for the
snub cylinders S' and lift cylinder 20. A flywheel and shaft 128
are mounted on the gear box 130 of the engine 132. The engine, for
example, may be a Detroit 8V92 575 horsepower (Detroit Diesel,
Detroit, Mich.), and utilizes a three-stage commercial gear pump
with three relief valves. The gear box may be a Durst PH 9 (Durst,
Shopiere, Wis.). In addition, although not shown, a series of
Denison vane pumps (Parker Hannifin HPD, Marysville, Ohio) are
provided off of the engine together with 3000 psi relief valves.
Another feature of the invention is that the complete engine power
pack may be stored in one of the containers 14, the pumps housed in
another container 14, the reservoir or tank in one of the
containers 14, and the remaining container 14 being utilized as a
tool house. In this way, the various engine, pump, and control
components will contribute to the weight necessary to stabilize the
entire rig and establish a low center of gravity to more than
counterbalance the weight of the derrick 12, pipe sections P and
lift cylinder 20.
[0050] In operation, the pipe sections P are stacked on top of the
pipe racks 51 and 52 with their ends in facing relation to the
derrick 12. Each pipe section P is raised either manually or with
the assistance of the pipe bracket 76 in order to wrap the winch
cable, not shown, around the end of the pipe and advance the pipe
over to the work basket where it is lined up beneath the elevators
99 on the lift cylinder 20. At this point, the end of each pipe
section P is engaged by the elevators 99 and lifted until the pipe
P is vertically aligned with the center of the well.
[0051] The snub cylinders S' are used only in situations where
there is some pressure in the hole, but normally the lift cylinder
20 is used throughout the entire process in lifting and lowering
each pipe section into and from the well. The three-stage pump 122
is controlled by the bank of controls on the control panel, one of
the pumps having one side that controls the snub cylinder S' when
necessary. All three pumps can be activated together as needed to
supply the necessary fluid under pressure to the main lift cylinder
20 via the flow control valves 101-103 and the control box 95. One
of the pumps is also connected to the rotary drive table. It should
be noted that the open or U-shaped front of the derrick 12 enables
automated lifting of each pipe section by the cylinder 20 through
an angular path of movement from the pipe racks up to the top of
the derrick 12 until the pipe section becomes aligned with the
wellhead. As the pipe section is then lowered by the lift cylinder
20 it will be engaged by the upper slips 140 (FIG. 27) and
threadedly connected to the next lower pipe section in the well.
The upper and lower slips 140 and 141 are of standard construction
and, for example, may be Cavins slip bowls (Cavins, Singal Hill,
Calif.). At this point, it will be apparent that standard procedure
can be followed in successively lowering each pipe section into the
well with the aid of the upper and lower slips 140 and 141.
Similarly, in lifting each pipe sections from the well, standard
procedure may be followed with the use of the slips 140 and 141 but
with the additional assistance of the elevator 99 on the lift
cylinder 20 for engagement with the upper end of each pipe section
and lifting to the height necessary to offload onto the pipe
racks.
[0052] After each well workover operation is completed, the pusher
cylinders are activated to advance the rig along the guideways 16
until the center bore 21 is alongside or aligned with the next
wellhead to be serviced. The hydraulic control circuit for the
pusher cylinders is represented in FIG. 7 and includes a two-bank
control 132 in order to simultaneously activate the cylinders 62
behind the containers 14. The cylinders 62 are push-pull cylinders
to advance the entire base structure in either direction along the
guideways. A pair of handle controls, not shown, may be mounted on
the end of one of the containers 14 to control the flow of fluid
from one of the pumps referred to in FIG. 25 to activate the
cylinders 62 as referred to earlier. If necessary, the derrick
slide plate 24 is activated to adjust the derrick 12 laterally into
alignment over the well to be serviced.
DETAILED DESCRIPTION OF SECOND EMBODIMENT
[0053] An offshore drilling 10' is illustrated in FIG. 26 wherein
like parts are correspondingly enumerated with prime numerals.
Again, the rig 10' is made up of a derrick 12' mounted on base
housing members or containers, not shown, which can be affixed or
mounted on the standard offshore drilling platform, not shown, and
therefore can utilize the existing positioning controls on the
drilling platform to advance the derrick into position for the
workover operation. The work floor 13' has the same components
including the catwalk, grating spacers, and pipe racks as described
in the first embodiment.
[0054] It is therefore to be understood that even though numerous
characteristics and advantages of the present embodiments have been
set forth in the foregoing description, together with the details
of the structure and function of the embodiments, the disclosure is
illustrative only, and changes may be made within the principles of
the embodiments to the full extent indicated by the broad general
meaning of the terms in which the appended claims are expressed and
reasonable equivalents thereof while preferred forms of the
invention are herein set forth and described, the above and other
modifications may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims and
reasonable equivalents thereof.
* * * * *