US3609981A - Ocean descent system method and means - Google Patents

Abstract

IN OFFSHORE OIL PRODUCTION OPERATIONS, A PLATFORM IS INITIALLY SECURED TO THE OCEAN FLOOR, AND A SUBMERSIBLE HOUSING IS THEREAFTER HAULED DOWN FROM THE OCEAN SURFACE IN PRECISE DIRECTIONAL OREIENTATION WITH RESPECT TO THE PLATFORM, AS REQUIRED FOR MATING OF STRUCTURAL ATTACH CONNECTIONS THEREBETWEEN. ORIENTATION IS ACHIEVED BY USE OF A U-SHAPED HAWSEPIPE ON THE PLATFORM, THROUGH WHICH THE HAUL-DOWN HAWSER IS THREADED, THE PIPE ENDS BEING SPACED APART A FIXED DISTANCE. A GUIDE ARM SYSTEM MOUNTED ON THE HOUSING ENGAGES THE HAWSER AT TWO LOCATIONS SPACED APART A DISTANCE COINCIDING WITH THE MENTIONED PIPE ENDS. LOOKING CONNECTION ELEMENTS ON THE PLATFORM AND HOUSING INTERENGAGE AUTOMATICALLY DUE TO PRECISE ORIENTATION THEREBETWEEN AS THE HOUSING MOVES INTO MATING RELATIONSHIP WITH THE PLATFORM.

Description

Oct. 5, 1971 R, 5, 300 3,609,981

OCEAN DESCENT SYSTEM METHOD AND MEANS Filed July 8, 1969 3 Sheets-Sheet 1 INVENTOR. ROBERT G. COOK AM Q ATTORNEY Oct. 5, 1971 R. G. COOK 3,609,981

OCEAN DESCENT SYSTEM METHOD AND MEANS III F/GTZ INVENTOR. ROBERT 6'. COOK A T TOR/V5 Y Oct. 5, 1971 R. G. cooK OCEAN DESCENT SYSTEM METHOD AND MEANS 3 Sheets-Sheet Filed July 8. 1969 INVISNTOR. ROBERT 6. 600K g max A T TORNE Y United States Patent Office 3,609,981 Patented Oct. 5, 1971 3,609,981 OCEAN DESCENT SYSTEM METHOD AND MEANS Robert G. Cook, San Pedro, Califi, assignor to North American Rockwell Corporation Filed July 8, 1969, Ser. No. 839,993 Int. Cl. E021) 17/02 US. CI. 61-69 7 Claims ABSTRACT OF THE DISCLOSURE In offshore oil production operations, a platform is initially secured to the ocean floor, and a submersible housing is thereafter hauled down from the ocean surface in precise directional orientation with respect to the platform, as required for mating of structural attach connections therebetween. Orientation is achieved by use of a U-shaped hawsepipe on the platform, through which the haul-down hawser is threaded, the pipe ends being spaced apart a fixed distance. A guide arm system mounted on the housing engages the hawser at two locations spaced apart a distance coinciding with the mentioned pipe ends. Locking connection elements on the platform and housing interengage automatically due to precise orientation therebetween as the housing moves into mating relationship with the platform.

BACKGROUND OF THE INVENTION Offshore oil production operations as currently practiced involve a multitude of economic and technological limitations which become rapidly more overwhelming as the depth of such operations increases. Recent interest in exploration and tapping of suboceanic oil fields in depths ten or twenty times greater than those now considered maximum will require development of new techniques and structures never before achieved in the prior art. Thus, many of the common techniques used for oil drilling and production in water depths of 300 to 600 feet are totally useless at depths beyond 600 feet. However, exploration plans currently envision oil drilling and production operations in depths of several thousand feet where hydrostatic pressure completely prohibit diver support and other expedients now widely used.

SUMMARY OF THE INVENTION The invention in this case involves essentially a twostep installation method for erecting complex structures on the ocean floor at depths as much as 6,000 feet. The novel method begins with installation of a polygonal base or platform 10 shown in FIG. 1 secured to ocean floor 12 by a plurality of upright pilings or stanchions 14. Platform 10 has a deck or upper surface 16 containing a center aperture 18 of essentially cylindrical form and concentric about a center axis 20 longitudinal therethrough. Platform 10 is further provided with a generally U-shaped hawsepipe 22 extending below the surface of deck 16 and having opposite spaced-apart ends 24 and 26. Hawsepipe 22 is securely affixed to platform 10 by suitable means and forms a permanent part of the platform structure. Installation of hollow airtight housings, either in unitary capsule or segmented form as required to complete the installation of equipment or habitable quarters on platform 10, is illustratively shown by reference to hollow housing shown in FIG. 1. Housing 30 is further provided with a rigid projecting brace or arm 34 having an elongate hollow cup or tubular fitting 36 secured to the distal end thereof. Housing 30 is further provided with locking means in the form of elongate probe 40 downwardly depending therefrom and centered within skirt portion 32 as shown in FIG. 1. In the descent mode, hawser 42 is secured at one end thereof to housing 30 by suitable means such as pin and clevis assembly 44 and the hawser is threaded through hawsepipe 22 and fitting 36 as suggested in FIG. 1, extending upwardly to a drum or motor driven winch (not shown) on the ocean surface. Operation of the mentioned winch causes upward pull on hawser 42 along the portion thereof which penetrates fitting 36, resulting in downward pull of the hawser portion connected to housing 30. Near the mating position between housing 30 and platform 10, it will be understood that the rotational position and lateral location of housing 30 are both determined and controlled by the relationship between hawsepipe 22 and arm 34. Thus, since the distance between clevis attachment 44 and fitting 36 substantially coincides with the distance between opposite ends 24 and 26 of hawsepipe 11, hawser 42 will pull or otherwise forcibly move fittings 36 and 44 into close proximity with ends 24 and 26. The foregoing alignment function performed by the arrangement of hawser 42 within hawsepipe 22 results in precise orientational congruity between probe 40 and center axis 20 of aperture 18 so that the locking probe and receptacle mounted on housing 30 and platform 10, respectively, will automatically interengage in a manner particularly shown by FIGS. 2, 4, and 5.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a side elevational view, partly in crosssection, of the novel structure with the two major components disengaged from each other,

FIG. 2 shows an isolated elevational view of a portion of the structure shown in FIG. 1 but with the two major structural components operatively engaged,

FIG. 3 shows a side elevational view, partly broken away, of a portion of the structure shown in FIG. 1 but with the marker buoys and pilot lines operatively associated therewith,

FIG. 4 shows a cross-sectional isolated view of the locking probe in an interim position of incomplate engagement between the two major component of FIG. 1, and

FIG. 5 shows a cross-sectional isolated view of the same structure as in FIG. 4 but with the probe in locking interengagement position securing together the two major components shown particularly in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the drawings mentioned above and particularly to FIG. 1, it may be seen that the inventive concept in this case contemplates a base or platform structure such as generally denoted by reference numerals 10. Base component 10 is supported on the ocean floor 12 and in vertically spaced relationship therewith by a plurality of upright pilings or stanchions 14. Platform 10 may be substantially round or polygonal in plan view or any other convenient shape, but in any case should have sufficient size and strength to support and retain the apparatus, protective housings or other such items which are sought to be secured proximate the ocean floor. For example, platform 10 may comprise a plurality of trusses in a star pattern projecting radially outwardly from a centerline 20. Platform 10 preferably has a substantially planar deck 16 containing a center aperture 18 wherein suitable means are situated for locking additional structure to the platform in a manner described more fully below. Platform 10 also is formed with a hollow U- shaped hawsepipe 22 permanently secured thereto and having opposite ends 24 and 26 spaced apart, upwardly directed, vertically oriented, and substantially parallel to each other. Hawsepipe 22 may be secured to platform 10 by any suitable means such as welded braces 28 shown in FIG. 1.

It will be understood that platform 10 and the elementssecured thereto as discussed above are initially mounted on the ocean floor before erection of the total structure contemplated in this case. After the mounting of platform in the manner shown in FIG. 1, means are provided for using hawsepipe 22 in subsequent operations for lowering deep oceanic structures into position on platform 10. Referring to FIG. 3, the foregoing means includes a pilotline 50 which is initially threaded through hawsepipe 22, preferably before platform 10 and components joined thereto are installed on the ocean floor. Pilot line 50 should comprise material having sufiicient strength and water resistance such as nylon, and is long enough to reach the surface at each of its ends while still threaded through hawsepipe. The opposite ends of line 50 each have a buoyant mass or float 52 and 54 secured thereto, suitable lengths of line 50 being stowed in floats 52 and 54 both of which can be released by suitable means when line 50 is needed for use. Floats 52 and 54 may be released from platform 10 by pulling lanyards 60a and 60b, which withdraw pins 56 and 58. Upon removal of pins 56 and 58, floats 52 and 54 are enabled to rise to the surface dragging the end of line 50 to which each float is attached. Thereafter, line 50 is used to install the hauldown cable or hawser 42 shown in FIG. 1, for example. Illustratively, float 54 may be removed from the end of line 50 on the ocean surface, and one end of hawser 42 may be secured to line 50 in place of the mentioned float. Thereafter, upward pulling are sought to be secured proximate the ocan floor. For exforce on the end of line 50 secured to float 52 on the surface by suitable means such as a winch (not shown), will result in downward pull of hawser 42 which should continue until the hawser is completely threaded through hawsepipe 22 and returns to the ocean surface through end 24 of the pipe. Thereafter, the hauldown operation discussed below may begin.

With hawser 42 completely threaded through hawsepipe 22 as shown in FIG. 1, for example, that portion of the hawser protruding from end opening 26 is secured to buoyancy housing 30 by any suitable means such as clevis 44. Thus, a pair of downwardly depending brackets formed on housing 30 has a looped end of hawser 42 secured releasably therebetween by a removable pin 46 which may be conveniently connected to such pin-pulling means as remotely operated cable 48 operatively associated with guide pulley 49 mounted on fitting 36.

Housing 30 incorporates stabilizing and control means co-operating with hawser 42 to maintain continuous direction orientation of the housing throughout its descent from the ocean surface to the ocean floor. The stated means include projecting arm support means 34 welded or otherwise secured to a depending skirt portion 32 on housing 30. Arm 34 has a hollow cup or cable follower fitting 36 affixed on the distal end thereof and through which the end of hawser 42 protruding from end opening 24 of hawsepipe 22 penetrates. From the foregoing arrangement, it will be understood that upward force on the end of hawser 42 and opposite from its connection with housing 30 will cause downward pull on the housing against the upward force resulting from buoyancy of the housing as it is hauled down deeper toward the ocean floor. During descent of housing 30 in the foregoing manner, rotation of the housing about an axis through the same and corresponding generally with center axis in FIG. 1 is effectively prevented by interengagement of fit, ting 36 and hawser 42. Moreover, since the spacing between the locations 36 and 44 where hawser 42 engages housing and structural components secured thereto, is essentially equal to the lateral distance between ends 24 and 26 of hawsepipe 22, it will be understood that housing 30 will be laterally and rotationally oriented in precise predetermined relationship with respect to platform 10 as required for interengagement of their respective attaching means, which function in the manner now to be discussed.

The mentioned attachment or locking means includes an elongate substantially cylindrical probe 40 downwardly depending from housing 30 as shown in FIG. 1, for example. Probe 40 is adapted to contact the sloping sides 62 of a generally conical receptacle 64 and to be guided thereby into a position of substantially concentric alignment with axis 20. Receptacle 64 is secured within center aperture 18 of platform 10, and is closely proximate probe 40 at the inner periphery of lower end portion 74 of the receptacle when both are fully operatively interengaged in locking position. Referring to FIG. 2, in the final position of interengagement between major components 10 and 30, probe 40 is retained within receptacle 64 and relatively horizontal motion is restrained by skirt lip 66 and platform earns 68 so that items 10 and 30 are correctly and precisely oriented. Thus, the end 26 of hawsepipe 22 is spaced from center axis 20 by a distance substantially coinciding with the distance between the center longitudinal axis of probe 40 and the center of clevis 44. The foregoing dimensional relationship, together with the fact the clevis 44 and fitting 36 are spaced apart a lateral distance substantially coinciding with the distance between ends 24 and 26, results in automatic alignment of probe 10 during the last few feet of downward travel of the housing.

Referring to FIGS. 4 and 5, it may be seen that probe 40 has substantially cylindrical portion 70 and a generally conical nose portion 72. Probe 40 extends from and is otherwise supported on hollow housing 30 by suitable means including motor mount 80. Mount has a massive flange 82 joined to housing 30 for transferring loads between probe 40 and the housing. Mount 80 further comprises an elongate, somewhat cylindrical portion 84 with a hydraulic or electric motor drive means 86 affixed on the upper end thereof and in sealing relationship therewith as suggested by ring seals 88 and 90 in FIG. 5. Mount 80 has a partition or flange-like projection 92 integrally formed therein and having a center aperture through which a jackscrew 94 extends from motor 86 to the upper portion 70 of probe 40. Thus, jackscrew 94 operatively engages the internal threads of a hole 96 formed in the center of cylindrical portion 70 and concentric with the longitudinal axis thereof. Upper and lower flanges 98 and 100 on jackscrew 94 engage the opposite sides of partition 92 in the manner suggested by FIG. 5, thus preventing relative vertical movement between the jackscrew and the partition. From the foregoing structural arrangement, it will be understood that rotation of jackscrew 94 by operation of drive motor 86 causes vertical translation of probe 40 relative to housing 30 due to force transmitted between the threads of the jackscrew and those on the inside of hole 96. For reasons discussed below, probe 40 is in the lowermost position relative to motor mount 80 during the descent mode, and is moved upwardly by actuation of motor 86 only after docking of housing 30 on platform 10 is otherwise completed.

Guide and restraining means are also provided to prevent rotation of probe 40 during translational movement thereof caused by rotation of jackscrew 94. The mentioned guide means may take the form of one or more downwardly extending pins such as suggested by pins 102 and 104 welded on or otherwise afiixed to partition 92 and extending into holes 106 and 108 formed in probe 40 and in sliding relationship therewith as suggested in FIG. 5. Vertical sliding movement of cylindrical portion 70 relative to the internal surface 110 of motor mount 80 is thus permitted by the operative relationship therebetween, while suitable sealing means are provided to prevent or minimize sea water leakage and may take'form of 0 rings 112 and 114.

As further seen from FIG. 5, probe 40 includes selfactivating interlocking means in the form of pivoting projection plates or blades 116 and 118 mounted within a hollow cavity in probe 40. Although only two blades are shown in FIGS. 4 and 5, it will be understood that 'four or more such blades may be used instead of only two. During the descent mode, blades 116 and 118 may remain extended in the position shown by FIGS. 1 and 5, for example, and are held in such position by suitable resilient means such as leaf springs or the like as shown by springs 120 and 122 seen in FIGS. 4 and 5. Each of the stated springs bears against a separate one of the blades 116 and 118 which are pivotally movable about stationary pins 124 and 126, respectively. As probe 40 moves downardly into receptacle 64, the narrow lower portion 74 of the receptacle contacts the outer distal ends of blades 11-6 and 118 and earns both blades into the retracted position suggested by FIG. 4 against the biasing force of springs 120 and 122. After probe 40 has moved downwardly through receptacle 64 a distance whereby blades 116 and 118 no longer contact the inner peripheral surface of portion 74 on the receptacle, both blades rotate outwardly through suitable slots in the opposite sides of cavity 130 under the force of springs 120 and 122 about their respective pivot centers through pins 124 and 126.

With blades 116 and 118 thus extended, means are provided for preventing radial inward movement of both blades such as would be necessary to retract the same into cavity 130. The stated means may take the form shown in FIG. 4 showing downwardly depending flanges 128 secured or otherwise formed on the upper end of cavity 130. Centered between brackets 128 a link 132 having a hole therein through which a pin 134 extends in the manner shown by FIG. 4. Link 132 is joined to a relatively heavy mass 136 having a nose portion 138 and conical side surfaces 140. Pin 134 releasably retains link 132 between brackets 128 in the position shown by FIG. 4 during descent of housing 30 and probe 40 from the ocean surface. During the final stage of descent, after the probe penetrates through receptacle 64 an amount sufficient to permit extension of blades 116 and 118 in the manner suggested by FIG. 5, pin 134 is pulled by any suitable means such as a control line 142 either automatically or manually operated upon complete interengagement of probe 40 and receptacle 64. When pin 46 is pulled laterally from the side of probe 40, mass 136, which has sufficient bulk or weight to drop vertically under the force of gravity, plunges downwardly into the position shown by FIG. 5, whereby conical surface 140 forcibly cams blades 116 and 118 radially outwardly and the cylindrical portion retains the same in the extended position to resist any loads applied to the blades which would tend to Withdraw the same. With blades 116 and 118 thus firmly held in the extended position, motor 86 may be actuated by any suitable remote means to rotate jackscrew 94 in a direction resulting in upward movement of probe 40, since the probe is in the downwardly extended position in relation to motor mount 80 prior to interlocking engagement with receptacle 64. Operation of motor 86 with blades 116 and 118 fully extended will result in upward movement of probe 40 until the bearing surfaces 144 and 146 of blades 116 and 118, respectively, contact the beveled edge 148 and 150 of lower portion 74 of the receptacle. When the blades are in the position thus shown by FIG. 5, actuation of motor 86 may be terminated and housing 30 will remain firmly interlocked with platform by the structural interconnection thereof as suggested in FIG. 2, for example.

I claim:

1. In structure for securing apparatus on the ocean a first structural component adapted for support on said ocean floor,

a hollow generally U-shaped hawsepipe affixed to said first component with the opposite open ends of said tube each being substantially vertically oriented and upwardly directed,

a second structural component adapted for support on said first component and hawscr means including a hawscr attached at one end thereof to said second component threaded through said hawsepipe for hauling said second component down to said first component by pulling upwardly on the other end of said hawser opposite from said one end. 2. The structure set forth in claim 1 above, further including:

a projecting arm on said second component, and a tubular fitting affixed to the distal end of said projecting arm, said hawscr being slidably threaded through said tubular fitting to maintain the directional position of said second structural component in general correspondence with the relative position of said one hawser end and said other hawser end. 3. The structure set forth in claim 2 above, wherein: said one end of said hawscr is attached to said second structural component at a predetermined distance from said tubular fitting, said distance corresponding to the distance between said opposite open ends of said U-shaped hawsepipe. 4. The structure set forth in claim 1, further including: interengagable locking means on said first and second structural components for securing both said components together in relatively fixed relationship, said locking means including an elongate probe on said second structural component and receptacle means mounted on said first structural component and adapted to receive said probe. 5. The structure set forth in claim 4 above, further including:

extendable blade means in said probe for preventing removal of said probe from said receptacle during mutual interengagement thereof, and holding means in said probe for holding said blade means in extended position. 6. A method of assembling at least two structural components on the ocean floor, comprising:

initially securing one of said components on the ocean floor, engaging a mid-portion of a hawser with said one component and in sliding relationship therewith, securing one end of said hawser to the other of said structural components, and applying upward pulling force to the end of said hawscr opposite from said one end to cause downward pulling force on said other structural component. 7. The method set forth in claim 6 above, further including: p

providing directional guidance to said other structural component with respect to said one component by engaging said other structural component with both upward and downward pulling portions of said hawscr.

References Cited UNITED STATES PATENTS 1,374,834 4/1921 Dooley 6l69 X 3,421,579 1/1969 Manning 6l69 X 3,477,236 11/1969 Burrus 6146.5 3,504,740 4/1970 Manning 166.5

J. KARL BELL, Primary Examiner

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