Note: Descriptions are shown in the official language in which they were submitted.
1042673
This application is a divisional application of
application Serial No. 236,397, filed September 25, 1975.
The present invention concerns, broadly, maneuvering
large and heavy equipments onto and from the sea floor. More
particularly, th~ invention concerns a support structure for
use in drilling and completing subsea oil and/or gas wells and
methods for installing the structure on and removing the struc-
ture from the sea floor.
In the past, most offshore drilling operations have
been conducted from a fixed, bottom supported platform which
rests on the sea floor and extends to the surface. However, as
offshore oil development progresses to deeper waters, fixed
platforms become prohibitively expensive to build. Generally,
it becomes uneconomical to utilize fixed platforms as water
depths approach 1000 feet. The present invention permits
economic drilling operations to be conducted at water depths
well in excess of 1000 feet by eliminating the need for a struc-
ture which extends above the surface of the water. The present
invention replaces the fixed platform with a completely sub-
merged template which rests on the sea floor. The size of thetemplate is a small fraction of the size of conventional deep-
water platforms and consequently, the template may be maneuvered
into place on the sea floor by methods unlike the cumbersome
installation procedures necessary to install a fixed platform.
As drilling and production water depths increase
beyond the point of optimum diver utilization placing such
structures on and removing such structures from the ocean floor
must be conducted remotely from a floating vehicle. Motions
induced by wind, wave and current create vessel-equipment
interactions which, if not properly controlled, can render
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conventional handling techniques worthless. In addition, such
structure placement and removal operations should include
utilization of a minimum number of marine vessels, the ability
to work under normal weather conditions, a relatively rapid
completion of the operations to preclude extended waits for
lengthy periods of good weather, and the ability to place the
structure in the correct geographical location and attitude.
The structure should also be designed for easy installation,
should be capable of withstanding the abnormal rigors of sea
; 10 floor existence, and should be retrievable at the conclusion of
its working life. The structure and methods of the present
invention meets all of the aforementioned requirements.
SUMMARY OF THE INVENTION
The present invention involves a subsea structure
which comprises a plurality of horizontal and vertical struc-
tural tubes arranged to provide support for the subsea oil
and/or gas drilling and production equipment. Certain of the
tubes are segregated to form compartmented ballast
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1042673
1 chambers or tanks capable of belng selectively flooded
2 or dewatered to achleve deslred negatlve or posltlve
3 buoyancies, respectlvely, so that the weight of the sub-
4 merged structure can be controlled to facllitate carrying
5 out the varlous required operatlons. The elevated loca-
6 tlon of the uppermost clrcumferential rlng makes lt very
7 useful ln generatlng a large water plane area for yield-
8 lng excellent floating stabillty and provides, also, a
9 high center of buoyancy in the submerged condltlons which
10 also contrlbutes to stability. In addition, thls rlng
11 serves as a fender to protect the equlpment surrounded by
12 the rlng from damage by dragging anchors or other submer-
J 13 ged ob~ects. Selected vertical structural tubes form plle
14 sleeves used ln securlng the structure to the sea floor.
15 Guide means are provided on the rlng to aid in guiding
16 equipment into the plle sleeves. Such equipment aids in
17 anchoring the subsea structure to the sea floor and for
18 releasing the subsea structure from the sea floor.
19 Orlentlng tubes are mounted on the periphery of the subsea
20 structure through which llnes are extendible to a surface
21 drllling vessel and to surface working vessels. The
22 drllllng and productlon equlpment on the subsea structure
23 lncludes a track for a manipulator which surrounds a
24 series of well bays, an antipollution pan, flowline
25 valves~ a framework for flowline connectors, electrical-
26 hydraulic units, a separator and pump unit and a buoyancy
27 control manifold having flood and vent lines extending to
28 the ballast chambers.
29 The method involved in maneuvering the subsea
30 structure to install it on the sea floor comprises the
31 ~tep~ of towlng the structure to ad~acent a drilling
32 vessel; connectlng llnes between the vessel and the
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1 structure and the structure and one or more working
2 ves~el~, ballastlng to trlm the structure level ~t the
3 surface;ballastlng the structure to a negatlve buoyancy;
4 keelhauling the structure to beneath the drilllng vessel;
lowering the structure to the sea floor; orienting the
6 structure geographlcally; pile founding the structure onto
7 the sea floor; cementing the plles in the sea floor and
8 then levellng the structure. The structure is removable
9 by ~everlng the piles and dewatering the structure to make
lt posltively buoyant.
11 BRIEF DESCRIPTION OF THE DRAWINGS
12 Flg. 1 is a schematic perspective view of the
13 subsea structure of the inventlon;
14 Fig. lA is a fragmentary view illustrating buo-
yancy control means;
16 Flgs. 2, 3 &nd 4 are respectively plan, side
17 and front vlews of the subsea structure of Fig. l;
18 Figs. 5 to 11, inclusive, illustrate schemati-
19 cally towlng the subsea structure into the launch area,
launchlng the structure from the tow barge into the water,
21 connecting the structure to the drilling vessel and then
22 keelhauling the structure to a position for lowering it
23 to the sea floor;
24 Flg. 12 ls a schematic illustration of the
lowerlng of the subsea structure to the sea floor;
26 Figs. 13 to 15 inclusive illustrate the pile
27 and means associated therewlth for placing the pile in
28 position and for cementing thereof;
29 Figs. 16 to 18 illustrate the pile sleeve and
lifting tool for leveling the subsea structure;
31 Figs. 19 to 25 illustrate schematically the
32 steps employed in cementing the piling in the ground
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1 underlying the water and ln cementlng the plllng in the
2 plllng sleeve; and
3 Flgs. 26 to 33 lllustrate schematlcally the
4 steps employed in removlng the subsea structure from the
ocean floor.
6 DESCRIPTION OF THE PREFER~ED EMBODIMENTS
7 As shown in Flgs. 1 and lA, a large boxlike
8 structure or template 10 designed for subsea use ln drlll-
9 ing and produclng submerged oil and/or gas wells lncludes
a truss or framework of interconnected vertical and hori-
11 zontal qteel tubular members 11 and l2, respectively,
12 whlch are segregated to form compartmented tan~s which
13 function as ballast chambers, and other steel tubular mem-
14 bers, which form pile sleeves 32 and cross support members
9 and 9a The large uppermost circumferential tubular
16 members 13 also form a protective ring or guard ~ender for
17 the equlpment supported on structure 10. That equlpment
18 includes production manlfoldlng 14 on whlch is mounted an
19 antlpollutlon pan 15 and which surrounds a number of well
bays 16, a track 17 surrounding the productlon manlfoldlng
21 and having a stralght track section 18 on whlch ls posi-
22 tioned an anchor 19 for a manlpulator and a releasable
23 buoy 20 for use in guiding the manlpulator to the track,
24 framework 21 for flowllne connectors, flowllne valves 22,
a separator and pump unit 23, a buoyancy control manifold
26 24, flood (water) and vent (air) lines connected to buo-
27 yancy control manifold 24 and the ballast chambers,
28 d eb a 1 la st t u b e ~1 0 m o u nt ed o n o ne o f
29 the corner B up p o rt tubes 9, and an electric-hydraulic
unit 25. As shown particularly in F~gs 1 to 4 template
31 10 is rectangularly shaped and has a bow 26 and a stern
32 27. A space 28, is formed ln the bow side of tubular
- 5 -
1 ring 13 to accommodat~ ~ow~ine connector apparatus and
2 a space 29, is formed in the stern side of tubular ring
3 13 to accommodate a power cable which extends from the
4 surface to the separator and pump unit 23. Power for
5 control system purposes is delivered through a separate
6 umbilical cable 25a extending through space 28.
7 Two L-shaped orienting tubes 30, each having
8 funneled ends and each being located in opposite diagonal
9 corners of template 10, are used in orienting template 10
10 and orienting line 31 is threaded through each of the
11 orienting tubes 30 as shown.
12 Four of the vertical tubular members 32 form
13 pile sleeves. Adjacent each pile sleeve are two guide
14 post sleeves 33.
Vertical tubular members 34 at the extremities
16 of template 10 are flooded as necessary to level the tem-
17 plate while it is floating at the surface to ensure that
18 it will submerge level. Preselected portions of the lower
19 horizontal tubular members 35 are flooded to change the
20 template from a positive to a negative buoyancy at which
21 buoyancy the wei~ht is maintained at a sufficiently low
22 value to permit handling of the template by conventional
23 apparatus. Thus, the template will remain at such nega-
24 tive buoyancy during lowering operations, orienting, pile
25 setting, cementing and leveling. Divers operate the
26 valves on the buoyancy control manifold to control the
27 ballasting operations while the template is at or near
28 the water's surface prior to lowering it to the sea floor.
29 Tubular members not flooded prior to or during the keel-
30 hauling and the change from positive to negative buoyancy,
31 including centrally located members 36 and buoyancy or
32 fender ring 13, are flooded after temp1ate 10 is on bottom,
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1¢)42673
1 leveled and piles set. The manlpulator operates the
2 valves on the buoyancy control manlfold to control fill
3 and vent operatlons once the template is posltloned on
4 the sea floor Upon an acoustic command from the surface
vessel, a buoy ls relea~ed from the template and the
6 manlpul~tor whlch ls positlvely buoyant upon launch hauls
7 it~elf down, lands, and latches on the track enclrcllng
8 the manl~old. Once latched on the track the manlpulator
9 ls ln a posltlon to remove malfunctlonlng parts of, ln-
st~ll replacements parts of and resurface carrylng used
11 components of the pretested equlpment lnltially lnstalled
12 on the template.
J 13 As shown ln Figs. 2 and 3 more particularly a
14 slngle tllt angle beacon 37 used to measure the angular
dlsplacement of template 10 durlng levellng ls positioned
16 ln an array wlth two locator beacons 38 whlch are used to
17 meaqure azimuth. Alternative similar arrays are shown
18 and may be deslrable as spares to forestall replacement
19 delays on deep-water systems. A backup hardware telemetry
system 137, 138 is also shown.
21 Fig. 5 shows template 10 being towed on a barge
22 42 by a vessel 43 to the slte of launch. As seen in Flg.
23 6 template 10 is connected to a drilling vessel 44 by a
24 control line 45 and to a work boat, not shown, by another
control line 46. As indicated, end tanks of barge 42 are
26 flooded to permit template 10 to sllde into the water.
27 In the position-shown in Fig. 7 the vertical trim tanks
28 34 are flooded, as necessary, to level template 10 at the
29 ~ter~s surface. As seen in Fig. 8 template 10 is warped
30 alongside drilling vessel 44. Pneumatic bumpers 47 are
31 po~tioned between template 10 and drilling vessel 44.
32 Keelhaul brldles l~3 and 49 are connected to the bow and
11~)42673
1 stern of the drilllng vessel and to the bow and stern of
2 the templ~te. The warplng lines are removed and the main
3 lowerlng sllng assembly 50 is attached to template 10.
4 ~he maln line 51 of sling assembly 50 ls keelhauled
through the drllling well (moonpool) 52 of drllllng ves-
6 sel 44 and connected to a preferably heave-compensated
7 hook 55 (as indlcated in Fig. 8) in the derrick. One
8 work boat 56 pulls template 10 away from drllllng vessel
9 44 a specified distance 53 to permlt template 10 to swlng
under and clear vessel 44 as lt is submerged. A work boat
11 57 may be connected to template 10 by line 58 and lt may
12 proceed upstream to a current control anchor if local
13 current conditions demand such a`ddltional control.
14 Anchors are set in a line ~ultable for azlmuth positlon-
ing of template 10 utilizing winches on drilling vessel
16 44. Figs. 10 and 11 show template 10 in position for
17 lowering relative to drilling vessel 44. The weight of
18 the template as it swings under drilling vessel 44 is
19 supported by lowering sling assembly 50. Template 10 is
raised Qlightly by line 51 and sling assembly 50 and
21 keelhaul lines 48 and 49 are removed.
22 Fig. 12 shows the relationship between drllllng
23 vessel 44 and template 10 as it is lowered through the
24 water to the subsea floor 60. The lines from anchors 63
which are the aforementioned orlenting lines 31 are taken
26 from the work boats and passed through orienting tubes 30
27 bow and stern of the template and connected to winches on
28 the bow and stern on drilling vessel 44. A pendant line
29 61 connected to a buoy 62 at the sur~ace is connected to
each anchor 63 as shown. ~ydrophones 64 located on the
31 underside of drill~ng vessel 44 in association wlth bea-
32 cons 37 and 38 contlnuously monltor the azlmuth positions
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104Z673
he temp:l~te 1~ l~wcr~ ~hr~u~h the wQter. A~m~th
~ ~ ading~ are made ~ust before ~ettlng the template on the
3 ocean floor. Tensloning on orienting lines 31 can rotate
4 template 10 to the desired orientation at which point tem-
plate 10 can be set on the ocean floor.
6 When properly landed lowering sling assembly 50
7 may be removed from template 10 by hydraulic lines con-
8 nected to pelican hooks (not shown) on the sling or by
9 mechanicRl release cables (not shown) operated from drill-
ing vessel 4~. Control llnes 156 and 58, if used, are
11 removed by running go-devils down the lines to releasable
12 connection 157 for retrieval by the work boats. Orient-
13 ing lines 31 are retrieved by picking up anchors 63 with
14 pendant llnes 61 and movlng towards template 10 while
reeving ln llnes 31 with winches mounted on drllling ves-
16 sel 44. As shackle 65 reaches drilllng vessel 44 the
17 upper segment of line 31 will be replaced with a synthetic
18 fiber rope 31a. The work boat will then proceed away from
19 template 10 drawing orlenting line 31 back down through
orientlng tube 30. Line 31 will be tensioned with line
21 31a so as not to foul template 10. As line 31 clears the
22 template 10, llne 31a wlll be Jettlsoned wlth buoy 31b
23 attached to prevent llne 31a from fouling the template.
24 As buoy 31b implnges on orlenting tube 30, tensloning
llne 31a will be stralned and parted. Llnes 31a and 31
26 will then be retrieved by work boat as will be buoy 31b.
27 The hea~lng for the drllling vessel mooring is
28 chosen to accommodate current and sea conditions at the
29 launch site. The drllllng vessel should be allgned with
the surface cùrrent during keelhaullng. Selectlon of the
31 drilllng vessel~s heading ls made to permit turning the
32 vesgel in its moorlngs durine placement o~ the template
1~)42673
-
1 to accommodate variables of current, wlnd, etc, Anticl-
2 patlon of such varlables will establish whether the drill-
3 lng ves~el is moored bow or stern to the current and the
4 relative position of the template,
Referring to Figs. 13, 14 and 15 and wlth par-
6 ticular reference to Fig, 13 there is shown the pile to
7 be inserted into and through plling sleeve 32 and the
8 means attached to the plle 70 for placing and cementing
9 plle 70 in place. Pillng 70 includes a cementing shoe
; 10 71, a lower retalner basket 72, an upper retainer basket
11 73, slips 74 and an upper funnel-shaped end 75, A spacer
12 plpe 76 ls connected into a collar 77 (see Flg, 14) to
13 whlch is connected a length of plastic plpe 78 which
14 extends down through plllng 72. Spacer pipe 76 has mount-
ed on it a hang-off tool 79 to whlch ls attached drlll
16 plpe 80.
17 Referring now to Figs, 16 to 18 ln which the
18 lifting tool for levellng the template ls shown in oper~t-
19 ing posltlon relatlve to the pile sleeve. Plling sleeve
32 has overflow slots 32a positioned ~ust below buoyancy
21 and fender ring 13, The top of pile sleeve 32 is provided
22 with two sets of J-slots 85 and a pile sleeve guide cone
23 86. The purpose of the overflow slots are to prevent
24 cement slurry from spilling over on production and other
equipments 14-24 and from entering the upper end of the
26 plling sleeve ad~acent the J-slots, A lifting tool 87
27 havlng a sleeve portion 87a and tapered plate members 87b
28 thereon is attached to drill pipe 89, A pair of J-~ugs
29 87c positioned 180~ apart are flxed on and extend outward-
ly from sleeve portion 87a, A strlnger or pipe 87d ex-
31 tends downwardly from the lower end of tool 87. Plate
32 members 87b guide ~nd center the tool 87 into the cone-
~6~4;~:673
1 shaped top 86 of plle sleeve 32 and allow the lugs 87c
2 to engage J-slots 85. Guide cables 90 extend to the
3 surface from guide posts 90a positioned in sleeves 33 and
4 guide frame members 91 posltioned about the cables 90 and
connected to lifting tool 87 guide the lifting tool down
6 into pile sleeve 32, On larger templates only three level-
7 ing pile sleeves may be used with several non-leveling
8 plle 61eeves.
9 The cementing and leveling operatlons are illus-
trated ln Figs. 19 to 25 lncluslve. Referrlng to Flg. 19
11 operations are begun on the lowest sleeve as indicated by
12 tilt beacon 37. A drill string 100 including a drill bit
13 101, drlll collars 102 and drill pipe 103 is guided from
14 drllling vesse? 44 lnto plle sleeve 32 by means of the
gulde means 91 and cables 90 and the plle hole 104 is
16 drilled to a desired depth, The hole is conditioned by
17 displaclng seawater with vlscous drllling fluid to pre
18 serve the hole. The drill string is then recovered to
19 the drill vessel. As illustrated in Figs. 20 and 21 the
pile assembly shown ln Flg. 13 is run lnto the pile hole
21 through the plle sleeve on drill pipe untll hang-off tool
22 79 reaches pile cone 86. Sllps 74 engage the inner wall
23 of pile sleeve 32 and allows upward mo~ement of plling
24 sleeve 32 but prevents downward movement thereof. Spacer
pipe (drlll plpe) 76 positions the top of the plle or
26 slips a distance D (approximately 10 feet) above the
27 bottom of pile sleeve 32. The spacer pipe 76 connects
28 into pile sleeve 32 by means of the adapter collar 77
29 (Flg. 14) which is threaded lnto plle 70 by left-hand
threads. Plastlc pipe section 78 extends from the under-
31 slde of the adapter collar 77. The upper and lower re-
32 tainer baskets 73 and 72, re~pectively, prevent prlmary
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~42673
1 cement from entering the pile sleeve annulus and the
2 secondary cement from golng below retainer basket 73.
3 Plastlc plpe 78 permits the primary cement slurry to re-
4 main free of seawater as lt ls pumped down the drill plpe
and through the plastic plpe. In the event the plastic
6 plpe becomes cemented in it can be twisted off when the
7 adapter and drill pipe are removed and left in piling 70.
8 A logging tool 105 (or detector) is run through the drill
9 plpe and through the piling assembly to detect cement as
lt passes uphole ln the piling annulus 106. The cement
11 slurry is mixed with radioactive material ln the first
12 batch thereof sufficient to provide a reading on the de-
13 tector when the cement passes the detector and also when
14 it moves up in the annulus 106. Thls assures that the
slurry is not being lost to formations. Cement ls then
16 pumped down the drill pipe and through the piling and the
17 cement shoe as illustrated in Figs. 24 and 25 until the
18 cement ls ~ust below the top of hole 104 as indicated by
19 raising logging tool 105. The cement is then permltted
to set and the drill pipe and adapter plus the plastic
21 pipe, if not cemented in, are removed from the hole. If
22 the plastic pipe is cemented in then it ls twlsted off
23 and left in the pile.
24 As lllustrated ln Figs. 22 and 23 lifting tool
87 is run on drill pipe with a stinger and stabbed into
26 pile sleeve 32 to engage lugs 87c into J-slots 85. The
27 drill pipe is then pulled up to raise the lowest corner of
28 template 10 while taking readings indicated by tilt beacon
29 37. A~ter each upward mo~ement of khe template the tilt
beacon i~ allowed to steady and is again read. The tem-
31 plate pile sleeve ls raised until template 10 is as near
32 level as can be achieved with the first or lowest sleeve
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1~)4Z673
1 32. AB shown in Fig. 23 the first sleeve 32 has been
2 ralsed a distance D'. Llfting tool 87 and drill pipe 89
3 are then removed. The pipe slips 74 will support the tem-
4 plate 10 in this position. The same operations are then
performed on the next lowest pile sleeve 32 as indicated
6 by the tilt beacon readlngs. The procedure for leveling
7 i9 repeated for each remainlng plle sleeve until the tem-
8 plate is level.
9 Figs. 24 and 25 illustrate the secondary cement-
ing procedure. Secondary cementing is begun in the last
11 plle used to level template 10. Cement is pumped through
12 the drill pipe connected to the lifting tool through the
13 lifting tool and into the top of piling 70 from which the
14 secondary cement overflows and fills the upper end of
plle sleeve 32 until the cement flows out slots 32a in
16 the plle below the fender ring 13. Cement also surrounds
17 slips 74 and the upper portion of pillng 70 down to the
18 top of retalner basket 73. The cement is permitted to
19 equalize and then the J-tool and pipe are raised up and
flushed with seawater. Then aballer is run through the
21 drill plpe to detect and sample the top of the cement.
22 The secondary cementing operatlons are repeated on each
23 of the remaining pile sleeves. The secondary cement acts
24 as a plug in the top of the pile sleeve and above the p1le
and also acts as a backup for slips 74. The secondary
26 cement permits recovery of the upper portion of the piles
27 70 and 51ip units 74 when the template is salvaged after
28 its use in that particular locatlon has terminated. In
29 addltlon, the secondary cement prevents the template from
moving off piles 70 during deballasting operations when
31 cutting or severing the piles as hereinafter described.
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1~4Z673
1 After all of the piles have been set and
2 cemented in, tubular structure members thus far remain-
3 lng dry on the template can be flodded to bring the tem-
4 plate to full submerged welght. Drilling o~ the wells
5 through the well bays in the template i9 commenced and
6 completion and productlon operations are carried out.
7 The remaining Figs. concern salvaging the tem-
8 plate. The wells are plugged and the well casings are
9 cut loose from the submerged productlon system equipment
10 on template 10. Referring to Fig. 26 then the secondary
11 cement is drilled out of pile sleeve 18 to ad~acent the
12 top of pile 70 ln the plle sleeve which is nearest to the
13 deballRsting tube 110 (see Fig. 29) which connects to the
14 ballast manifold 24. The pile is then drilled out to 10
15 feet below the cutoff point of the pile as illustrated in
16 Fig. 27. The drill pipe is then pulled and a cutting tool
17 assembly 112 on which is mounted a marine swivel 113 for
18 seatlng in pile cone 75 i8 run into pile 70 and the pile
19 is cut off as indicated at 114. The drlll pipe 103 and
20 cutting tool 112 attached to it are then pulled.
r 21 Before proceeding to cut a second pile debal-
22 lasting operations are begun. Referring to Fig. 29 a
23 compressed air adapter stab unit 115 is connected to the
24 lower end of a drill pipe 116 (which contains a ~ar 117
25 ~ust above adapter 115) on the drilling vessel. The air
26 hose 118 to the work boat is keelhauled from the compres-
27 sor on the work boat under the drilling vessel through the
28 moon well and attached to the adapter unit then the ada-
29 pter 115 and drill pipe 116 are lowered together with
30 guide frame 119 and the adapter is stabbed and locked
31 into the deballast tube 110. Air is then pumped through
32 tube 110 to the bu-,yancy control mani~old 24 and then to
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~4;~673
1 the ballast tanks formed by the tubular members to force
2 water out of the.n, A release sub 120 contalns a shear
3 pln, That shear pln ls sheared by ~ar 117 to release the
l~ drill plpe connectlon from the adapter 115 and the drill
pipe 116 i8 removed, As seen in Fig. 30 the air continues
6 to deballast the ballasting tanks,
7 Then the diagonally positioned pile sleeve 32
8 and the pile thereln are drilled out as dis~ ssed above
9 and the plle ls cut and removed ln the same manner as dis-
cussed above,
11 The remalnlng two plles are preferably cut ex-
12 plosively. Referring to Figs, 31 and 32 after drilllng
J 13 out the cement as descrlbed above a telescoping tool or
14 locater sleeve 120 provlded wlth at lts upper end a land-
ing head 121 and having a shear pin connection 122 to the
16 lower end of lifting tool 87 to whlch ls connected a re-
17 lease sub 123 on drill pipe 124 is run into pile 70 until
18 landing head 121 lands on the pile cone 75 as shown. An
19 electrical cable 125 extends from the wbrk boat lnto the
locater sleeve 120 and a cable 126 connects the lifting
21 tool to the work boat, A sub 127 on the locater sleeve
22 120 is provided with outlet ports 128, Locater sleeve
23 120 con$ains an explosive compounds such as a plastic
24 explosive compound, The locater sleeve 120 positlons the
outlet ports at the deslred cutoff point in pile 70,
26 After head 121 lands in cone 75 pin 122 is sheared and
27 lifting tool 87 is lowered until lugs 86c on the lifting
28 tool are locked in the J-slots of the pile sleeve. This
29 downward movement forces the explosive compound through
the ports into dlrect contact wlth the inner wall of pile
31 sleeve 32. Such telescopic movement also arms the unit
32 for firlne, The e~plosive compound is moved through
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16)4Z673
1 outlet ports 128 as indicated in Fig. 32. Thereafter the
2 drill pipe 124 is released from sub 1~3 above lifting tool
3 87. A slmilar operatlon ls performed in the diagonally
4 positioned pile sleeve, i.e. the pile sleeve is cleaned
out and another locater sleeve containing explosive is
6 run into that pile. Both the electric cable and the other
7 cable 126 are connected at the surface to a second work
8 boat.
9 Deballastlng operatlons are halted. The drill-
ing vessel ls removed from the area. The deballasting is
11 brought to a desired state. The charges are fired remote-
12 ly from the work boats at short intervals. The released
13 template is controlled by control lines and the work boats.
14 As shown in ~ig. 33 the template rises to the water sur-
face. When template 10 is afloat all the valves are
16 manually closed by divers and the template is towed to
17 port.
18 Changes and modifications may be made in the
19 ~pecific illustratlve embodiments of the invention shown
and/or described herein without departing from the scope
21 of the inventlon as deflned in the appended claims. Thus,
22 as mentloned previously, instead of four piles two or
23 three piles or more than four piles may be used. In
24 additlon,the manner of ballasting and deballasting the
manlfold may vary according to desired operations.
26 Further the manner of salvaging the template may be
27 changed. All of the piles may be explosively cut or all
28 may be mechanically cut.
29 Having fully described the method, apparatus,
ob~ects and advantages of our invention we claim:
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