CA1212100A - Method of installing, levelling and securing a subsea template - Google Patents

Method of installing, levelling and securing a subsea template

Info

Publication number
CA1212100A
CA1212100A CA000490015A CA490015A CA1212100A CA 1212100 A CA1212100 A CA 1212100A CA 000490015 A CA000490015 A CA 000490015A CA 490015 A CA490015 A CA 490015A CA 1212100 A CA1212100 A CA 1212100A
Authority
CA
Canada
Prior art keywords
template
piles
seabed
sleeves
hoisting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000490015A
Other languages
French (fr)
Inventor
James E. Hampton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sedco Inc
Original Assignee
Sedco Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB8202491 priority Critical
Priority to GB8202491A priority patent/GB2094856B/en
Priority to CA000420393A priority patent/CA1203228A/en
Application filed by Sedco Inc filed Critical Sedco Inc
Priority to CA000490015A priority patent/CA1212100A/en
Application granted granted Critical
Publication of CA1212100A publication Critical patent/CA1212100A/en
Expired legal-status Critical Current

Links

Abstract

Abstract The present invention relates to a method of installing, levelling and securing a subsea template on a seabed. The method is comprised of the steps of providing a floating vessel including hoisting apparatus for raising and lowering a template with respect to the seabed; providing a template structure comprising a frame having a plurality of spaced apart pile receiving sleeves formed thereon, the template including a unit associated with the sleeves for releasably gripping piles disposed in respective of the sleeves for securing the template to the piles. The method further includes the steps of positioning the template with the vessel over a predetermined point on the seabed and lowering the template to the seabed; installing a selected number of piles in respective ones of the sleeves and extending adjacent to the gripping unit, respectively;
lifting the template with the hoisting apparatus to level the template with respect to a predetermined reference level condition; actuating the gripping unit to connect the template to the piles, respectively; and lowering the template with the hoisting apparatus to transfer the weight of the template to the piles through the gripping units.

Description

` -- lZ~L2 I

A Method of S sea Template This is a division of cop ending Canadian Patent Application Serial number 420,393 which was file on January 27, 1983.

Field of the Invention The present invention pertains to a method and apparatus for installing and leveling subset drilling and/or foundation templates and the like using a semi-submersible drilling rig equipped with a heave compensator.

Background In the art of developing subset install lotions for production of hydrocarbons from form-anions below the seabed there have been numerous types of installations placed on the seabed including structures known as templates and the like These structure are typically characterized by large skeletal frames which are used for support-in Waldo components and other apparatus used in conjunction with drilling and producing hydrocarbons from subset wells.
There are several problems associated with handling the relatively large structures known as templates, The process of loading, transporting and installing a subset template using a semi-` - Lo submersible drilling rig or other floating structure has presented several problems in the overall procedure of handling the templates from the point of embarkation to the final installation and level-lying procedure.
In particular r it is difficult to properly position or level a subset template from a floating structure unless sea conditions are totally calm, a rare occurrence in many offshore oil fields, paretic-ularly areas such as the North Sea. The leveling procedure is, however, desirable and necessary in order that the template or other related structure be property oriented with respect to a floating drill rig, for example, which will be working lo through and utilizing the template. Moreover, a leveling procedure using a floating vessel such as a semi submersible drilling rig, which may be constantly changing its elevation with respect to the seabed as a result of sea conditions, has pro-sensed several problems in the art of installing subset templates. However, the present invention provides an improved method and apparatus for installing and properly leveling a subset template or the like using a floatillg drilling rig or a similar floating vessel equipped with hoisting apparatus. In particular, the present invention pertains to an improved method and apparatus using a semi-submersible floating drilling rig equipped with a heave compensator or the like I

SUMMARY OF THE INVENTION
In accordance with an aspect of the invention there is provided a method of installing, leveling and securing a Swiss template on a seabed comprising the steps of providing a floating vessel including hoisting apparatus for raising and lower-in a template with respect to said seabed;
providing a template structure comprising a frame having a plurality of spaced apart pile receiving I sleeves, formed thereon t said template including means associated with said sleeves for releasable gripping piles disposed in respective ones of said sleeves for securing said template to said piles positioning said template with said vessel over a predetermined point on said seabed and loweril1g said template to said seabed; installing a selected number of piles in respective ones of said sleeves and extending adjacent to said gripping means, respectively; lifting said template with said hoisting apparatus to level said template with respect to a predetermined reference level condition; actuating said gripping means to connect said template to said piles respectively; and lowering said template with said hoisting apparatus to transfer the weight ox said template to said piles through said gripping means.
The present invention taken in conjunction with cop ending Canadian Patent Application Serial number 420,393 which was filed on January 27, 1983, will be described in detail hereinbelow with the aid of the accompanying drawings, in which:

zoo Figure l is a plan view illustrating a them plate being loaded on to a semi-submersible column stabilized drilling rig with its main deck structure removed;
Figure 2 is a side elevation illustrating an intermediate step in loading the template on the drilling rig;
Figure 3 is a view similar to Figure 2 showing the template being set on a hull of the lo drilling rig;
Figure 4 is a cutaway plan view of the semi-submersible drilling rig showing the location of several templates in their loaded positions;
Figure 5 is a view taken along the line 5-5 of Figure 4;
Figure 6 is a section view taken along the lines 6-6 of Figure 4;
Figure 7 is a side elevation showing a center loaded template being lowered into position 2Q on the seabed;
Figure 8 is a perspective view of a portion of the drilling rig illustrating the leveling procedure;
Figure 9 is a plan view of the tensioning I winch assembly taken from the line 9-9 of Figure 8;
Figure lo is a side elevation showing one of the templates being unshipped from a hull of the semi-submersible drilling rig;
Figure if shows the installation of the template unshipped in Figure lo at a predetermined site on the seabed;

-\

legwork 12 is a central section viva of a pile slip assembly used in conjunction with the template levclling procedure of the present invention; and figure 13 is a section view taken along the line 13-13 of logger 12.
DESCRIPTION OF THE PREREAD E~llBODI~1ENTS
In the description which tallows like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and certain features of the invention may be exaggerated in scale or shown in schematic form in the interest of clarity and conciseness.
Referring to Figures 1 through 3 there is illustrated a floating drilling rig of the type known in the art as a kiloton stabilized semi-submersible rig and which is generally designated by the numeral 20. The rig 20 is of the variable draft type and comprises spaced apart longitudinal submersible hulls 22 which are interconnected by a suitable framework including a main deck structure 24 and spaced apart vertical corner columns 26. The rig 20 is adapted to include a drilling derrick 28, one or more deck mounted boom cranes 30 and a plurality of deck mounted powered drum type winches 32. The rig 20 is also adapted to include conventional drilling rig hoisting and drill stem rotating apparatus tvhich will be described in further detail herein.
The hoisting apparatus may include a suitable dra~v~vorks, generally designated by the numeral I in rigors 2 and 3. In the vivace of figures 1 through 3 the drilling rig I has previously been positioned over a template 36 and has loaded the template to be suspended from the derrick 28 by the aforementioned hoisting nppnratus all bet~veell the spaced apart hulls 22. The template 36 is a skeletal frame type Sue structure which will be described in some further detail herein in conjunction with Figure 8. The procedure ox Lou cling and securing the template 3G is described in the above referenced cop ending application which is assigned to tile assignee of the present invention.
S Referring further to figures 1 through 3 there is illustrated a procedure for loading additional templates, each designated by the numeral 38, which may be, for example, foundation templates for a tension leg platform or may comprise further drilling templates or other suitable support structures to be deposited on and secured to the seabed. As shown in Figure 1, with the rig 20 suitably anchored in a calm harbor or other anchorage, the templates 38 are loaded on to the fig by transferring the templates from a barge 40 utilizing a floating crane 42. Referring briefly to Figures 5 and 6 the hulls 22 of the drilling rig are provided with support frames 44 on which are mounted spaced apart finlike stall guides 46 vouch are adapted to receive in locating and supporting relationship spaced apart pile sleeves 48 forming part of the friar; work of the templates 38. Each of the guide sleeves 48 is provided with a downwardly facing cone portion 49 to facilitate location and inter engagement of the stab guides with the respective sleeves. The templates 38 may also be provided with preinstalled stab guides 50, Figure 6, locatable in stab receiving cones 51 welded to the framework; 44.
Figure 2 illustrates the floating crone 92 in position for loading a template 38 on to one of the support fumes on a hull 22 using a sling 60 as indicated. The template 38 is preferably provided with suitable fair leads, not shown, through which guide cables 54 anal 56 are run from respective ones of the winches 32 to tile Support flume 44. third one of the winches 32 includes a tugger line 58 secured to -G -~L2:~2~

the template 38 to aid in positioning the template QVcr the support frame 44. us shown in logger 3 the starbo~rcl side fleck crane 30 it also brought into operation by being conllectcd to the template 38 during the final positioning process on the hull 22. The templates 38 are of a type which include buoyant hull structures which my be flood able to control the buoyancy of the templates, respectively.
Accordingly, the hulls 22 may be submerged to a pullout wherein as each of the templates 38 is lowered into position on its associated support framing I the template is submerged to a floating position. At this point a suitable ballast control line is connected to the template and the template is ballasted until it is securely disposed on the frame 44 and until a certain amount of negative buoyancy is obtained. This may be measured by suitable weight inclicntor apparatus associated with the starboard deck crane 30.
After each respective one of the templates 38 are located in position Oil the associated hulls 22 the sling 60 associated with each template is left with the template for use by the rig hoisting apparatus to remove the template for installation at the preferred site. Each template 38 is loaded out from the barge 40 by the floating crane 42 and positioned on the rig 22 in the general arrangement indicated in logger 4. Lyle the rig 20 is Ludlow with the requisite number of templates including a template 36 suspended from the derrick hoisting apparatus and also supporter by suitable hanger apparatus, not shown, the rig can proceed to the offshore site for installation of the templates. Upon reaching the predetermined site for installation of the templates the rip 20 is anchored and deballasted in accordance with procedures Lyon in the art, and dependent on sea conditions, propel Tory to installation of the templates 3G and 38 .

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Upon reaching the predetermined site for install-anion of the template 36, for example, the aforementioned template hanger mechanism is disconnected from the template and the template is lowered to a predetermined site on the seabed 17, as shown ion Figure 7.
Referring to Figure 8 the template 36 is shown in position on the seabed 17 suspended from the derrick 28 by apparatus including an elongated riser string 62 and a flexible sling 64 connected to respective points on the template 36 equidistant from the riser string and such that the center of gravity of the template 36 is substantially coaxial with the longitudinal axis of and below the riser string 62. The template 36 is provided with suitable inclinometer or other level indicating units generally designated by the numeral 37 positioned on the corners of the templates 36 adjacent spaced apart vertical pile receiving sleeves 39. The template 36 is also provided with an improved slip assembly associated with each of the pile sleeves 39, generally designated by the numeral 41, for gripping respective elongated support columns or piles 43 which extend through the pile sleeves 39 and are driven and/or cemented Pinto the seabed 17. The template 36 is also provided with a hydraulic control pod and receptacle arrange-mint of a type known in the art of subset well apparatus and generally designated by the numeral 65 which is adapted to supply pressure fluid to each of the slip assemblies 41 by way of a hose bundle or umbilical 66 lowered from the rig 20.
The procedure of lowering the template 36 into position, and inserting the piles 43 into the pile sleeves is described in United States Patent No. 4,435,108 which issued to JOE. Hampton on March 6,-1984. The aforementioned application also describes a preferred method of positioning the template 36 prior to drilling and/or driving ~2:12~0~ `

the piles I With the piles in position as shown in figure 8 and with the umbilical I run from tile rig 20 to the tcmpl~te so that control of the slip assemblies 41 May be exercised from on board tile rig 20, from a suitable submersible vessel, not shown, or by divers positioned to view the level condition of the tempklte, the leveling procedure of the present invention can be carried out using improved apparatus in accordant with the present invention.
Referring further to Figure 8 it Jill be noted that the drill fig 20 is provided vital a drill stem heave or motion compensator, generally designated by the numeral 70. The heave compensator 70 is of a type vouch is commercially available and one type of compensator which will operate in conjunction with the apparatus and method of the present invention is a heave or motion compensator manufactured by NO
Rig Equipment Division of NO Industries, Inc., listen, Texas, under the trademark ROCKER. The heave compensator 70 is suspended from the derrick hoisting apparatus includirlg a crown block, not shown, and a cable arrangement revved through a traveling block 71 connected to the compellsator. The motion compensator 70 includes a hook 72 from which spaced apart elevator links or bails 74 are suspended and are connected to a suitable riser elevator 76. The riser string I is suspended from the elevator 7G arid the upper end of the riser string also supports a unique tensioner assembly generally designated by the numeral 78.
The tensioner assembly 78 comprises a generally rectangular frame 79, see Figure 9, along one side so which is secured a short section of drill collar or sub 80. The frame 79 also supports a motor driven drum type winch or so called air tugger unit generally designated by the numeral 81. The winch 81 includes a winch I

drum on hill an elollgated tensioner cable 82 is wound nod extends from the vanish downward through a rotary table 83, supported on the rig platform 33 loath its Lyle bushing removed. The riser stying Go nil the cable 82 extend downward through n moon pool 89 formed in the main declc 24 and the cable I is trained over a shelve 85 suitably collected to structure associated with the deal; 24 in the vicinity of the moon pool . As illustrated in l inure I the keelhaul 82 extends downward from the rig 20 and is connected to one of the piles 43. The winch 81 is of a type having a pressure fluid operated motor 87 vouch is operable to exert a substantially constant torque on the winch drum to maintain a constant predetermined tension in the cable 82. The vanish motor I is adapted to be connected to a Silas of pressure air such as a compressor I by vay of a suitable fly control valve 99 indicated schematically in Figure 8. The tensioner assembly 78 is aciapted to be Lo supported by the the riser string 62 by suitably coupling the sub 80 tothe upper end of the riser string. Accordingly the tensioner assembly 78 is adapted to move Ruth the riser string 62 relative to the rig 20 in response to movement of the heave compensator 70 to compensate for motion of the rig under certain sea conditions.
The improved leveling procedure previously mentioned is carried out after the piles 43 have been inserted in the pile sleeves 39 and tune rig 20 is suitably positioned substantially over the center of the template 36 and the rig mooring system is normalized. with the rig 20 properly positioned the riser string 62 is run to a point above the template 3G and the sling assembly 64 is connected to the template.
The slillg assembly 64 may be connected to the template by submarine diver s dispatched from the rig 20 or a suitable surface or submarine support vessel. The riser string Go is disconnected from the heave I

compensator 70 assuring that there is enough slack in the lifting slings Go and set on a spider or slip assembly, not shown, suitably separately by the retooler table 83.
it this point, an underwater television camera 91 can be run from the rig 20 on suitable guidelines 93 and focused on one of the piles 43 which is provided with suitable indicia such as spaced apart bench musks 99 so that movement of the template relative to the pile can be observed. The inclinometer units 37 can also be viewed by a television camera or the units may by of a type which are capable of transmitting signals directly to a suitable receiver on the rig 20, for example, to indicate the level condition of the template 36.
kite divers are positioning the television camera 91 and/or the sling assembly 64 the tensioner assembly 78 can be suitably connected to the riser string with the sub 80. The heave compensator 70 is then lowered to permit connection of the links 74 to the Hoyle 72 and the tensioner assembly 78 together with the riser string 62 is pickled up by the rig hoisting apparatus 34. it the riser string ô2 and the tensioner assembly 78 attached to the hook 72 the rig hoisting apparatus is raised until there is approximately, for example, eight feet of slickly in the sling assembly 64. At this time, the tensioner line 82 may be lowered through the rotary table 83 to the moon pool, trained over the sheave 85 and run to the template 36 using, for example, a guideline, not shown, for the hydraulic control pod 65. Tile tensioner line 82 is then connected to one of the piles 43, as illustrated in Figure 8, and pressure air supplied to the hoist motor 87 at a pressure sufficient to support the weight of the tensioner line So.
At this point, if the control pod 65 is not already connected for supplying pressure fluid to the slip assemblies 41 this procedure is
2~0~.

carried out in accordance with known techniques for connecting subset hydraulic connector assemblies Suckle no the control pod I to mating pod receptacles. The template 36 is now ready for the final levclling process vouch comprises pressurizing the hydraulic system of the heave compensator 70 to position the compensator at about mid length its working stroke at which point it will normally Tess up the weight of the template 36. The compensator 70 is then additionally pressurized until the template 36 is in a level plane as indicated by the inclinometer units 37. The tcle~rision camera 91 is then focused on the reference pile including the aforementioned inclicia or bench marks 94 and movement of the template 36 relative to the pile is observed. The pressure air supply to the winch motor 87 is increased to increase the tension in the line 82 while observing the dampening effect on the relative movement between the template 36 and the aforementioned reference pile. Tension in the line 82 is adjusted until there is no relative movement between the template and the reference pile whereupon the template is level and motionless .
At this point the signals from the inclinometer units 37 are rechecked to ensure that the template is level within the allowable tolerance. If the template is level within tolerallce the slip assemblies 41 are activated to grip the piles 43 to secure the template US to the piles. After activation of the slip assemblies ~11 the rig hoisting apparatus is slacked off to allow the weight of the template to be transferred on to the piles to set the slip assemblies and the inclinometer readings are rechecked to determine if the template is still level within tolerance. If the template level is not within tolerance the rig hoisting apparatus is operated to pick up on tile traveling bloat;
and the heave compensator 70 to take the weight of the template. The - Lo I

slips 41 ore theft activated to retract and the above tlescribed procedure is carried out until the template is level anal locked. At this time, the hy~lrnulic control poet 65 can be retrieved and divers can be jumped to disconnect the sling assembly 54 and the tensioning line 82.
The tensioning line 82 may be reshaclcled to the aforementioned guideline for the control pod 65 and retrieved to the moon pool then removed from the guideline and pulled back through the rotary table 83 by rotating the drum of the winch assembly 81. The riser string 62 and slinks 64 may then be retrieved in a conventional manner.
Referring briefly to Figures 12 and 13 one of the slip assemblies 41 is illustrated in longitudillal central section view and wherein the figure illustrates to the left of the longitudinal centerline the slip assembly in its actuated position and to the right in its retracted position. The slip assembly 41 is described and claimed in a cop ending application filed concurrently herewith. Ever, certain features of the slip assembly will be described hereinbelow to facilitate a better understanding of the operation of the slip assembly.
The slip assembly 41 is adapted to surround a pile 43 and to trippingly engage the pile as vowel be evident from the following description. The slip assembly 41 includes a frame comprising upper and lower ring shaped abutment plates 151 and 153, respectively, which are secured to and spaced apart by a cylindrical tubular wall member 152. An annular slip bowl 154 is disposed within the enclosure formed by the frame plates 151 and 153 and includes upper and lower plates 155 and 157 which are spaced apart by an outer cylindrical wall 158 and a conically tapered inner wall 160. The slip bowl 154 fits loosely between the plates 151 and 53 and is operable to center itself radially with respect to the longitudinal central axis 147 of the slip flssembly.

Lo Lo The slip bowl 154 is also operable to move axially end to tilt with respect to the central axis of the slip assembly within thy limits imposed by the frame plates 151 and 153 to accommodate some skew misalignment of the pile with respect to the slip assembly.
The lower plate 153 is supported by a cylindrical tubular frame member 161 which is secured to a mounting ring 163 and defines a receptacle 145 in which the pile 43 is disposed together with an actuator for the slip assembly to be described herein. The mounting ring 1~3 is supported by and secured to a base plate 164. The base plate lG4 is supported on and secured to a sleeve 1~6 and a mounting flange 191 by a plurality of radially extending gusset plates 168. The slip assembly 41 is also provided with a cylindrical outer housing member 172 disposed around the frame portion formed by the plates 151 and 153 and fixed thereto by a plurality of radially projecting gusset plates 165. The gussets 165 are also secured to lower and upper conical plates 173 and 174, disposed below and above the housing member 172, as shown. The conical plate 174 forms a guide funnel for guiding a pile into the central receptacle in the frame of the slip assembly .
The slip assembly 41 is also provided with a plurality of slip segments 176 which are disposed generally within the tapered slip bevel wall 160 in surrounding relationship to a pile. The segments 176 are preferably formed of case hardened steel and are arranged to engage a pile as shown by the position of one of the slip segments on the left side of the central axis of the slip assembly in Figure 12~ The slip segments 176 are each in the form of a circular segment or sector portion, are preferably provided eight in number and are interconnected nod biased outwardly agrlinst the wall lG0 by suitable slick annular resilient retaining springs 175 fitted in cooperating grooves in tile inner wall surfaces of the slip segments. The spurns 175 may be ormolu us n resilient steel split ring, for example, not unlike a piston ring and operable to bias the slip segments radially outward with S respect to the assess 147 against the inner wall 160 of slip bevel. Thesegments 176 include a sloping outer wall 179 and a cylindrical inner wall 181, the latter being provided with a series of gripping teeth or serrations for gripping the outer surface of a pile. Toe segments 176 are also provided with slots 177 formed in the opposed sidewalls of the segments The slots 177 are adapted to receive oppositely projecting trunnions 178 which are attached to spaced apart brackets 180 mounted on a circular guide ring 182.
The slip assembly 41 further includes hydraulic actuator means comprising an annular hydraulic cylinder 183 having a lower head member 184 which is supported on an anti-friction ball bearing assembly including a ball housing 186 supported on the base plate 164 and adapted to include bearing elements 187. The cylinder 183 is adapted to form a chamber 185 having an annular piston 188 disposed therein and connected to a piston rod portion 189 which is vertically extendible and retractable with respect to the cylinder through an upper head member 190 and is in supportive relationship with the guide ring 182.
Pressure fluid is supplied to cylinder 182 to act Oil opposed faces of the piston 188 through suitable conduits 191 and 192, which are connected to the receptacle of control pod 65.
In response to application of pressure fluid into the portion of annular cylinder chamber 185 formed below the pistol 188, the guide ring 182 is moved upwardly which in turn moves the slip segments 176 against the tapered inner wall 160 to force the segments radially 121~L0~

inwardly islet gripping engagement with the outer circumfcI entail surface of the pile 122. Moreover, the weight of the template acting through the slip segmellts 17G tends to self energize the segments into>
tighter gripping engagement with the pile.
The templates 38 may also be installed and leveled utilizing the procedure described above for installation and leveling of the template 36. However, the procedure for locating the templates 38 on the seabed is somewhat different due to their initial stowed position on respective ones of the hulls 22. After the rig 20 is located in a predetermined position for installation of one of the templates 38 the hulls 22 are controllable ballasted to be sure that the draft of the rig is sufficient to permit floating of the templates 38 after venting ballast from the respective ballast compartments and these templates.
Referring to Figures 10 and 11, one of the templates 38 is shown with a ballast vent line 100 connected thereto for venting ballast iron one or more of the aforementioned compartments and a snubbing line 101 is run from the starboard deal; crane 30, for example, and is connected to the template 38 utilizing sling assembly 60 similar to the sling 64. The snub line 101 is trained through a suitable opening in the deck 24 and over a deck mounted sheave, not shown. A lifting line 105 is run to the sling 60 from the lower end of the riser string 52, which is suspended from the rig hoisting apparatus, and is pulled up into the area of the moon pool and suitably tensioned.
The template 38 is positioned under the moon pool by venting template ballast ulltil the template floats free of the supporting and locating structure previously described and the lifting line lo is klken up as the snub line 101 is slacked off until the template is in position under the moon pool. Additional transverse snub lines may be required depending on sea and currant conditions. Louvre it is contemplated that it is possible to hold the template 38 in pOSitiOII by runlling a very tight lift assembly with five to ten foot seas and a slack tide condition.
The guidelines 54 and 56 are adjusted during the template positioning procedure nod disconnected and cleared from the template prior to lowering the template to the seabed. The template 38 is then laurel into a predetermined position on the seabed 17 generally using the sari e procedure as used for positioning the template 36. The templates 38 may be leveled in the same manner as described above for the template 36 and also utilizing level instrumentation disposed on each one of the templates 38 in generally tile same manner as used for the template 36.
Alternatively, the templates 38 may be leveled screw jacks, not shown, and a drill string lowered from the hoisting apparatus of the rig 20 and the rotary table 83 and including a screw jack stinger assembly and bumper sub connected to the drill string with one drill collar connected to the string below the bumper sub. The riser string 62, lifting line 105 and sling 60 are first disconnected from the template I and derigged. The drill string may then be tripped down to the template on preinstalled guidelines, not shown, and an offset frame, also not shown. The levellirlg instrumentation is consulted to select the low point of the template and the drill collar is stabbed in and rotated until the template is leveled. The sequence is then repeated until the template is within . 50 degrees of level, preferably . The drill string and screw jack stinger are then recovered and rigging for a pile driving hammer or other pile insertion procedures in commenced.
All of the templates 38 are installed using basically the same procedure Vito modifications as required depending on the position of the declc crones 30 with respect to the location of the templates on the hulls 22.
Those skilled in the art will upprccillte from the foregoing description that impruvcd methods and apparatus have been developed for locating and levclling subset structures such as drilling and foundation templates and other structures which must be held motionless in preferred attitude on the seabed and installed by a floating vessel such as a semi-submersible drilling rig or other vessel which is in a buoyant mode in or on the sea. although preferred embodiments of the invention have been described in detail herein those skilled in the art will also recognize that various substitutions and modifications may be made to -the methods and apparatus of the invention without departing from the scope and spirit of the invention as recited in the appended clumsy .

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method of installing, levelling and securing a subsea template on a seabed comprising the steps of:
providing a floating vessel including hoisting apparatus for raising and lowering a template with respect to said seabed;
providing a template structure comprising a frame having a plurality of spaced apart pile receiving sleeves, formed thereon, said template including means associated with said sleeves for releasably gripping piles disposed in respective ones of said sleeves for securing said template to said piles;
positioning said template with said vessel over a predetermined point on said seabed and lowering said template to said seabed;
installing a selected number of piles in respective ones of said sleeves and extending adjacent to said gripping means, respectively;
lifting said template with said hoisting apparatus to level said template with respect to a predetermined reference level condition;
actuating said gripping means to connect said template to said piles respectively; and lowering said template with said hoisting apparatus to transfer the weight of said template to said piles through said gripping means.
CA000490015A 1981-01-28 1985-09-04 Method of installing, levelling and securing a subsea template Expired CA1212100A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB8202491 1982-01-28
GB8202491A GB2094856B (en) 1981-01-28 1982-01-28 Slip assembly for subsea template
CA000420393A CA1203228A (en) 1982-01-28 1983-01-27 Installation and levelling of subsea templates
CA000490015A CA1212100A (en) 1982-01-28 1985-09-04 Method of installing, levelling and securing a subsea template

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA000490015A CA1212100A (en) 1982-01-28 1985-09-04 Method of installing, levelling and securing a subsea template

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CA000490015A Division CA1212100A (en) 1981-01-28 1985-09-04 Method of installing, levelling and securing a subsea template

Related Child Applications (1)

Application Number Title Priority Date Filing Date
CA000490015A Division CA1212100A (en) 1981-01-28 1985-09-04 Method of installing, levelling and securing a subsea template

Publications (1)

Publication Number Publication Date
CA1212100A true CA1212100A (en) 1986-09-30

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CA000490015A Expired CA1212100A (en) 1981-01-28 1985-09-04 Method of installing, levelling and securing a subsea template

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109515737A (en) * 2018-03-16 2019-03-26 陕西飞机工业(集团)有限公司 A kind of plane airfoil balancing device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109515737A (en) * 2018-03-16 2019-03-26 陕西飞机工业(集团)有限公司 A kind of plane airfoil balancing device

Also Published As

Publication number Publication date
CA1212099A (en) 1986-09-30

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