Note: Descriptions are shown in the official language in which they were submitted.
~o~93~37
LOGISTICAL SUPPORT OF OFFSHORE DRILLING FACILITIES
Field of the Invention
This invention pertains to marine transport systems
and, more particularly, to a marine transport system for
logistical support of offshore drilling facilities from
shore-based supply locations and in which modularized cargo
hold units are used.
Background of the Xnvention
The State of the Art
Exploration for and production of oil and gas
reserves underlying the oceans of the world are performed
from ~ffshore drilling facilities which usually are located
some distance from the adjacent shore line. The drilling
facility may be a tower erected on the sea floor and extending
to a work platform above the water surface, or the drilling
facility may be a floating platform. The floating platform
may be either of the drillship type or of the semi-submersible
type; in either event, the facility is located for long
periods, perhaps even permanently, offshore often at
substnatial distances from the nearest available port or
supply location.
An industry has developed to logistically support
offshore drilling facilities. As presently defined, this
11 1069387
1 industry is composed generally of independent contractors
to the owners and operators of the ofshore drilling
facilities. These independent contractors own fleets of
one or more supply vessels which, depending upon the areas
in which they operate, are usually designed with reference
to the particular climatic and sea conditions likely to be
encountered. A typical offshore supply vessel is either
- designed specifically for a given limited purpose or as a
compromise amongst the competing factors pertinent to other
requirements of the logistics for offshore drilling facili-
ties. An example of a special purpose vessel is a crew boat
which is designed to ferry personnel to and from offshore
drilling facilitiesO An example of a multifu~ction design
compromise offshore support vessel is a work boat which, at
various times in its life, is called upon to transport
tubular goods such as drill pipes or production casing to
the offs~ore drilling facility, or to transport food or dry
or liguid bulk goods and supplies to the drilling facility,
or to serve as an anchor-handling boat in ConneCtiQn with
the initial positioning and mooring of a floating offshore
drilling facility. Because a workboat typically constitutes
a design compromise to enable the vessel to serve multiple
functions, it is of less than optimum characteristics for
the performance of any one function.~
2 An offshore support vessel, such as a crew boat or a
work boat, constitutes a substantial invest~ent to îts owner.
Such vessels are idle much of their useful life since they
must be tied up at the dockside at the shore-basedsupply
location to take on and to discharge cargo; they are simi-
3 larly idle for even longer periods in the course of
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discharging cargo to and receiving cargo from an offshore
driIling facility. Transfer of cargo between an offshore
drilling facility and a support vessel is generally a time
consuming and hazardous process because the cargo must be
transferred piecemeal by use of boom cranes and the like
mounted on the drilling facility. These cargo transfer
operations at the drilling facility often must be performed
with respect to a support vessel which is pitching, heaving,
and rolling as the vessel responds to passing wave trains.
0 It is not uncommon for support vessels to be damaged or for
cargo to be lost during this transfer processO
The speciic patent references considered in the
preparation of this patent application are as follows:
U.S. 10,843 Young 1854
15U.S. 1,076,068 Schleieher 1913
U.S. 1,226,055 Bohn 1917
U.S~ 2,371~149 Bylo 1945
U.S. 2,894,650 Black 1959
U.S. 3,139,197 Bylo 1964
20U.S. 3,191,568 Schroeder 1965
U.S. 3,349,742 Bylo 1967
U.S. 3,399,792 Che~ter- 1968 -
U.S. 3,417;721 Vienna lg68
U.S. 3,557,742 Gainsley 1971
2U.S. 3,793,974 Bylo 1974
U.SO 3,934,532 Bylo 1976
Gr. BF. 1,022,374 Pedrick 19~6
Summar~ of the Invention
_ _ _ _ _ _ _ _ _ _ _
This invention provides significant economic and
practical movements in the mechanics of logistical support
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¦ of offshore dxilling facili~ies from shore-based supply
¦ locations. Economically, this invention is of significance
both to the owner or operator of ~he offshore drilling
~ facility and to the operator of the support vessel. This
5 ¦ invention enables a support vessel to be in productive use
¦ a maximum amount of its useful life in actually moving cargo
¦ or personnel between offshore drilling facilities and adja-
cent shore-based supply locations. This invention enables
¦ the support vessel to be optimally configured for any
0 ¦ activity it is called upon to perform at any given time.
¦ This invention minimizes the time which a support vessel
must spend taking on or discharging cargo at a shoxe-based
¦ location; more significantly, it minimizes the time which the
¦ vessel must occupy in a cargo transfer operation at an off-
15 ¦ shore drilling facility.
¦ This invention incorporates, either directly or with
the modifications described below, many of the structures
and procedures described in my prior U.S. Patents Nos.
2,371,149, 3,139,197, 3,349,742, 3,793,974, and 3,934,5~2.
~0 My prior patents describe marine transport structures
and systems in which the cargo space of a vessel is occupied
substantially exclusively by one or more modular hold units
which are of standard modular design, at least over the
lower exterior portions thereof. A vessel is designed to
mate with the lower portions of any one of the cargo holdunits and to ~ecuxe the hold units laterally in position on
the vessel so that, during operation of the vessel to move
the hold units from one place to another, the hold units
cannot shift on the vessel. The vessels described in my
prior patents are basically self-propelled receptacles for
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the deck units and are composed pr~cipally of a hull,
appropriate machinery, necessarv navigation and equipment
space, and minimal crew accommodations. In a preferred
marine transport system according to my prior patents, a
number of vessels are used with a greater plurality of deck
units to move cargo between adjacent ports in an integrated
multiport transport system, the deck units being trans-
ferred from one vessel to another in passing through any
given port in the system. At least some, and preferably
all, of the ports in the system are equipped with dock
facilities arranged to support any one of the deck units
above a slip into which a vessel may move and to support
the deck unit independently of the presence of a vessel in
the slip. The uessels include ballast systems which enable
the vessels to buoyantly move up and down into and out of
receiving and supporting engagement with a deck unit sup-
ported in the dock facility, thereby to accomplish the
transfer of a given deck unit from a given vessel to and
from the dock facility. While the deck units are supported
in the dock facilities in the absence of a vessel, cargo may
be worked to and from the deck unit. The vessels are thereby
freed from lying idle in port during cargo handling opera-
tions and spend a maximum possible percentage of their use-
ful li~e in actually transferring the deck units and cargo
therein between ports in the system.
As noted, this invention proceeds from the principles,
structures and methoas aescribea in my pri~r pate~s a~
provides an improved system for logistical suppor~ of offshore
drilling facilities from a shore-based supply location.
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In accordance with the present invention there is
provided apparatus for logistical support of an offshore
drilling facility from a shore-based supply location comprising
1~ a plurality of modular work deck units for
generally rectangular plan shape and of generally uniform
external configuration and dimension over the bottom and lower
side and end portions thereof,
2) a self-propelled vessel having an exposed deck
portion dimensioned and configured to releasably mate with and
to support any one, and only one at any time, of the work deck
units and cargo carried thereby in substantially laterally and
longitudinally fixed position on the vessel, the vessel includ-
ing ballast means operable for increasing and decreasing the
draft of the vessel when mated with a work deck unit sufficient-
ly that the vessel can ballast down from a separately supported
deck unit and move out from thereunder,
3) a plurality of dock facilities at the supply
location defined in cooperation with the vessel and the work
deck units
(a~ for movement thereinto of the vessel with a
work deck unit thereon and
(b) for engaging and supporting a work deck unit
therein
(i) for loading and unloading of cargo to and
from the deck unit, and
(ii) for transfer to and from the vessel in
response to ballasting of the vessel,
4) a deck unit-to-vessel receiving and discharging
station at the offshore drilling facility,
5) the offshore drilling facility including a
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platform elevated above the adjacent water surface, and
6) the receiving and discharging station including
elevator means at an elevated location in the drilling facility
and engagable with a work deck unit, the elevator means being
operable for engaging a work deck unit supported by the vessel
and for raising and lowering a deck unit to and from a receiving
location elevated in the offshore facility above the water
surface.
Description of the Accompanying Drawings
The above-mentioned and other features of this
invention are more fully set forth in the following detailed
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1 ~ descr tion of presently preferred embadiments o~ the
invention, which description is presented with reference
ag appropriate to my prior patents and with reference to
the accompanying drawings wherein-
FIG. 1 is a perspective view of an improved offshore
support vessel in the course of transferring a work deck.
unit to or from an offshore drilling facility;
FIG~ 2 is; a perspecti~e view of a shore-based supply
location showing the dock facilities at the supply location;
0 .FIG. 3 is a perspective view of alternate dock facili-
ties at a shore-based supply location;
FIG. 4 is a perspecti~e view of a general purpose work -~
deck unit mated with the support vessel;
FIG~ 5 is a perspective view of another work deck unit; and ;:
~5 FIGo 6 is a perspective view of another dock facllity. ~ :
. Description of the Illustrated Embodiments
.. . FIGS. 1 and 2 show a presently preferred offshore
drilling platform support and supply s~stem 9 according to
this invention which i-ncludes at least one offshore drilling
20 platform 10, a shore-based supply location 11 which includes
. plurality of dock facilities 12, at least one self-propelled ~ .
essel 13 ~sometimes referred to herein as a "bottom"), and
; plurality of modular work deck units 140 The term "offshore
. rilling piatform" is used-broadly with reference to.platform
1.0 and encompasses both a platform used for actual explora-
ory or ~roduction drilling of a subsea oil or gas reserve
. . nd ~lso a production platform which is operated to produce
il or gas from the subsea reserve after the drilling
rocesses have been completed.
Within the overall system, vessels 13 function in a
manner analogous to forklift trucks to pick up a work deck
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1 unit from either the drilling platform or the shore-based
supply location (base~ and to move the deck unit to the
other of the platform or base.
As shown in the drawings, the work deck units 14 are
S of generally rectangular configuration when viewed in plan,
i.e., either from above or below, and define as a part of
their structure a central longitudinal depending rib 15
which is of uniform dimension and configuration as between
the several work deck units of the system. Each work deck
10 unit is defined to project laterally horizontally outwardly ~,
from the rib along the elongate sides of the rib. The
overall width of each of the deck units may be greater than
the beam of the self-propelled vessels in the system. While
the different work deck units contemplated by this invention
lS are described in greater detail hereinafter, it is noted at
this point that the upper portions of each work deck unit is
confi~ured, arranged and equipped in conformance with a
specialized function in which each work deck unit serves in
the overall system. As between the several work deck units,
however, the deck units are all of generally uniform external
configuration and dimension over both the bottom thereof,
specifically as to ribs 15, and also over the lower side and
; end portions thereof.
` Each self-propelled support vessel, such as vessel 13
shown in FIG. 1, defines an upwardly open, elongate, longi-
tudinally aligned deck well 16 aft of a forward bridge and
accommodations structure 17 below which, within the interior
of the vessel hull, is located the appropriate machinery for
propulsion o the vessel and for operation of the ballast
system which is included in the vessel as hereinafter
10~93t~7
described. Well 16 preferably occupies a major poxtion
of the length of the vessel and is open through the stern of
the vessel as best shown at 18 in FIG. 1 ~see also FIG. 4).
The geometry of the well, both i~ terms of its overall
dîmensions and its local features, is defined in mirror
image conformance to the configuration of the ribs 15 defined
by each of work deck units 14. As noted above, the beam of
vessel 13 may be equal to or less than but preferably not
greater than the width of any of the wo~k deck units. The
beam of the vessel relative to the width of the work deck
units is determined depending upon the particular nature of
the dock facility (compare FIGS. 2 and 3) which is provided
at base 11.
As more fully described in my prior patents (see
particularly patents 2,371,149, 3,139,197, and 3,793,974)
each vessel 13 includes sufficient internal ballast space
to enable the vessel, when mated with a loaded work deck
unit, to be ballasted down (to increase draft) sufficiently
to enable the vessel, when positioned in a dock facility,
to transfer the weight of the work deck unit and its load
to the dock facility and thereafter to further increase draft
sufficiently that the vessel can move out from under the
separately supported work deck unit. Also, the ballast
capacity of each vessel is sufficient that the bottom when
. L~ bare~ i.e., when~engaged with ne work deck unit, can be
given sufficient draft that it can move into a dock facility
below a separately supported loaded work deck unit and to
ballast up (to decrease draft) through a distance sufficient
to enable the vessel to move into engagement with the work
deck unit and to transfer from the dock facility to the
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l vessel the weight of the woxk deck unit and its load.
Depending upon the nature of the deck unit-to-vessel
receiving and discharging station at the offshore drilling
platform lO, the ballast capacity of the vessel may be
required to be adequate to enable the vessel to change
draft sufficiently to discharge a deck unit from or to the
vessel into the water, and also to move empty under and to
ballast up to a floating deck unit to assume its weight.
Where a work deck unit is to be deposited in the water at
an offshore drilling platform, the deck unit is watertight
over its lower portions and has sufficient buoyancy to
support itself and its load. As to the nature of the
ballast system which is included in each vessel 13 in a
support system according to this invention, reference is
15 made to my prior patent 3,793,974. -
As shown in FIG. 2, at the base or onshore supply
location 11, a plurality of dock facilities 12 are provided
Each doc~ facility defines a slip 20 of sufficient length,
width, and water depth that a support vessel 13 may enter
the slip, preferably stern to in the case of the dock
facilities shown in FIG. 2, and eithe-r discharge or take
on a work deck unit by ballasti~g down or up, respectively,
out o or into load transferring engagement~ith a work deck
~ bnit separately supported in the dock facility. In view of ~5 the content of my prior patents, it is believed unnecessary
to describe in detail herein the specific cooperative
structural relationships which can be used between the dock
facilities, the vessels, and the work deck units to enable
the deck units to be separately supported above the slip in
each dock facility. In this connection, reference is made,
` ~0693~7
1for example, to my prior patents 2,371,149, 3,139,197, and
~,793,974. Patent 2,371,149 is of interest where the width
of the deck units is greater than ~he beam of any of vessels
13 so that the work deck units may be transferred betwèen
the vessels and the dock facilities simply by ballasting of
the vessels. Patent 3,139,197 describes arrangements at a
dock facility which provide for vertical movement of a deck
unit in the dock facility supplemental to the vextical move-
ment of the vessel due to ballasting. Any of the dock
0 facility and deck unit interfaces desc~ibed in either of
these two patents, or in my later patent 3,793,974, may be
used as desired within the scope of th-s invention.
FIG. 3 illustrates another dock facility 22 which may
be provided at a supply base in a system according ~o this
invention. Dock facilities 22 include pairs of parallel
rows of pilings 23, the rows being spaced from each other
an amount corresponding to the width of slip 20 as shown in
FIG. 2. The upper ends of the pilings serve as the struc-
tural features for registering with the portions of the -
several work deck units which extend laterally outwardly
beyond the beam of vessel 13 for engaging and supporting the ;~
work deck uni~s separately from the vessels.
As noted above, the several work deck units in any
offshore drilling platform support and supply system accord-
ing to this invention may all be different in structuralorganization and layout in their upper aspects whîle being
of uniform configuration and dimension over their lower
aspects for cooperation of any wor~ deck unit with any vessel
13 in the system. The variability of the upper aspects of a
work deck unit ~nablesany given work deck unit to be designed
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1 and equipped for optimum conformance to a specialized
purpose to which that work deck unit is assigned within
the system. For example, in FIGS. 2 and 3, work deck unit
14A is specifically defined, especially in its aft portions,
as an anchor-handling unit for use in placing the mooring
anchors for a floating offshore drilling platform according
to practices which are standard in the offshore drilling
industry. Those aspects of wor~ deck unit 14A which are
specifically adapted to the handling of anchors will readily
0 be recognizable fro~ the accompanying drawings to persons
involved in the offshore drilling industry and the related
support industry, to which persons this invention is
addressed.
Similarly, wor~ deck units 14B shown in FIGS. 2, 3 and
4 are specifically designed and equipped as cargo platforms
for the receipt and transport of general stores to an off-
shore drilling platform. WorK deck unit 14C, shown in FIG.
5, is designed as a cargo platform or the transport of
tubular goods, i.e., steel drill pipe, well casing, prodNction
tubing, or the like, to an offshore drilling platform. While
not shown specifically in the accompanying drawing, it is
apparent that additional work deck units in the system can
be designed and ëquipped operationally for service as a diving
station, on-site laboratories ~as, for example, a Schlumberger
logging equipment and analysis facility for use on an off-
shore drilling platform specifically during drilling opera-
tions), or as an equivalent of a crew boat.
In most instances, worldwide, where offshore drilling
operations are being conducted, many offshore drilling plat-
3 forms are located in a localized offshore geographical area
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106938~
1 forsupport and supply out of one or a few ports or bases.A typical exam~le of this situation is encountered in the
Gulf of Mexico and offshore from California adjacent Santa
Barbara and Ventura. This invention, as described above,
S makes it possible for a given offshore platform support and
supply concern to make maximum use of its vessels which nor-
mally are the most expensive pieces of equipment owned by s~ch
an operator. It will be apparent that, according to this
invention, a given offshore support and service contractor
0 can service substantially more offshore drilling platforms
more effectively on a better schedule with a glven capital
investment, or the contractor can effectively service more
efficiently a given number of offshore platforms with sig-
nificantly reduced capital investment. This is so because
5 each vessel 13 is essen~ially continuously in use moving ~i~
between the shore-based supply location and the several off-
shore drilling platforms adjacent the supply location. This -
is so because the vessel, upon arriving at the shore-based
supply location, can rapidly enter a slip at an open dock
facility, deposit the work deck unit carried by the vessel,
leave the first slip and back or otherwise enter into an
adjacent slip at another dock facility below a different
loaded deck unit which may be of the same or a different type
as the deck unit previously deposited, transfer the loaded
2 deck unit from the second dock facility to the vessel, and
leave from the second dock facility to another offshore
drilling platform. At the supply location, the different
work deck units owned by the operator can be loaded at
leisure with the material to be dispatched to any one of
3 the adjacent offshore drilling piatforms when either the
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~0 69 387
1 same or a different vessel in the fleet next arrives at
the supply location. The economies realized by the operator
of a support and supply concern are particularly discernible
when it is realized that an anchor-handling vessel, as
presently defined, is usefully occupied on its specialized
~asks only a small percentage of the time.
The economies produced for an offshore support and
supply operator are particularly great at the "other end of
the line," i.e., at offshore drilling platform 10 which,
0 according to this invention, includes a vessel-to-deck unit ~-
receiving and discharging station 30. In FIG. 1, offshore
drilling platform 10 is illustrated as a semi-submersible
platform in which multiple surface piercing pylons 31 are
arranged to provide slips 32 between them and into which a
loaded vessel 13 may move into position below the operations
deck 33 of the platform which is supported above the water
surface by the pylons. In the arrangement shown in FIG. 1, -~
the receiving and discharging stations 30 are defined as
openings in the platform operations deck, the openings being
2 dimensioned to correspond to the overall transverse and -
longitudinal dimensions of the work deck units 10. The
. 6L6V~D~
receiving and discharging stations also include appropriate)
eguipment, such as winches (not shown) and cables 34 the
ehds of which carry suitable connectors capable of being
2 lowered into engagement with suitable fixtures defined in
the work deck units for receiving the weight of a work deck
unit and its load from a vessel. The weight of a work deck
unit and its load is transferred between the platform and
a support vessel either by ballasting the vessel downwardly
3 ~rom the separately supported position of the work deck unit
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as shown in FIG~ 1, or by taking in the cables to raise the
work deck unit to the level of the platform operations deck,
or by a combination of both practices. In any event, at
the offshore drilling platform, a loaded work deck unit is
rapidly discharged from a newly arrived vessel and held in
an appropriate position at the platform for unloading of
cargo and the like from the work deck as by use of a boom
crane 36 included within the equipment of the platform. As
shown in FIG. 1, the best practice of this invention is
0 believed to be achieved where the platform includes two or
. more receiving and discharging stations 30, whereby the
vessel upon discharging to the platform a newly arrived
. work deck unit and its cargo may move into the position
. . .below a second work deck unit which is to be sent back to
the shore-based supply location.. In this manner vessel 13
.. is not required to return empty from the platform to the
supply base, with resulting economies in the use of both the
vessel and the work deck units..
Those persons in the industries to which this invention
is addressed will readily recognize that the principles of
this invention may be used to great advantage with existing
offshore drilling platforms which aO not include work deck
...
unit receiving and discharging stations of the type shown in
~IG. 1. Accordingly, this invention contemplates that the
~ 2 work deck receiving and discharging station at an existing
;. offshore drilling platform may be provided by the addition
to the platform of a waterline mooring arrangement at which
a buoyant work deck unit may be moored for transfer of cargo
from the deck unit to the platform safely as prevailing
3 conditions permit, all in the absence of a vessel tied up
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1 alongside the platform. In this latter instance, it will
be apparent that the work deck units used to supply cargo,
stores, and equipment to an existing offshore platform must
be of a buoyan*ly floatable naturej,and that the ballast
capacity of vessel 13 must be sufficient to enable the
vessel to move into position under the floating work deck
unit at the offshore platfoxm.
. ...
FIG. 6 shows a supply location 11 in which the dock
facilities àre defined parallel to the edge 41 of a wharf
0 40 of the type'typical along rivers. In this instance a
slip 42 i9 defined by a row of pilings 23 parallel to the
~harf' edge 41 and spaced from the wharf edge by an amount
corresponding to the width of a slip 20 in FIG. 2. The
wharf edge and the piling ends cooperate to support a
received work deck unit as shown in FIG. 6. Dock facilities
',- of the type sho~n ln ~IG. 6 can be used to advantage on a ,~
river or the like where vessel maneuvering room may be
limited. An advantage,of the parallel dock facility, as
compared to the end-on slip arrangements shown in FIGS. 2
20 and 3, is that vessel 13 can pass through slip 42 in
depositing a work deck unlt. The different arrangements
shown in FIGS. 2, 3 and 6 illustrate the flexibility and
versatility of this invention.
Workers skilled in the art and technology to which
' 2 this invention pertains will appreciate that the foregoing
description has been presented by way of example and illus- -~
tration with reference to the illustrated presently preferred
embodiments and arrangçments of this invention, and that the
foregoing description is not an exhaustive presentation of
3 all forms which this invention may take as to itS procedural
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1 and structural aspects. Such workers will.recognize that
modifications, variations and adaptations may be made to
the arrangements described above without departing from
; the fair scope and substance o~ this invention. For these
. 5 reasons, the preceding description is not to be read or
construed as limiting thls invention only to the specific ~ .
. arrangements and procedures which have been described.
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