GB2107766A - Method and apparatus for remotely cutting broken underwater guidelines - Google Patents

Abstract

An apparatus and method are disclosed for remotely cutting a broken guideline (11) extending from an underwater guide post (12). The apparatus includes a frame (31), a clamping mechanism (34) for clamping the frame to an annular groove (149) in the guide post, a pair of opposed, pivotable cutting jaws (38, 39) coupled to the frame, and a remotely actuable power device (91) coupled to the jaws by a U-shaped driver member for pivoting the cutting jaws across the longitudinal axis of the broken guideline to sever the guideline from the guide post. Above the cutting jaws are a pair of pivotal loom jaws (36, 37) which guide the assembly on the post and also deflect any interfering portion of the broken guideline extending along the side of the post. The method includes lowering the frame, jaws and clamping mechanism through the water to a position in which the clamping mechanism is below the annular groove in the guide post, slidably coupling the clamping mechanism to the guide post, raising the clamping mechanism upwardly until it is received in the groove and then actuating the pivotable cutting jaws. <IMAGE>

Description

SPECIFICATION Method and apparatus for remotely cutting broken underwater guidelines The invention relates to a method and apparatus for cutting a broken guideline extending from an underwater guide post forming part of, for example, a subsea well.

In the subsea exploration and production of oil and gas, instaliations are frequently located at the seabed with a plurality of guidelines extending upwardly from guide posts and coupled at sea level to a platform or vessel. These guidelines are used to lower or raise various equipment with connecting devices being coupled to the equipment and being slidable along the guidelines.

Due to the extreme environment of such subsea installations, these guidelines frequently break and must be immediately replaced to continue the subsea operations. To accomplish this replacement, it is advantageous to sever the broken guideline from the guide post from which it extends. In addition, this severance should be as close to the top of the guide post as possible to facilitate replacement.

However, there are two basic problems involved in cutting off the broken remnant of a subsea guideline. The first is the difficulty of remotely guiding a cutter mechanism to the exposed top of the guide post. The other is the difficulty of remotely positioning the guideline itself relative to the cutting mechanism.

In accomplishing this cutting of the broken guideline, the positioning of the cutting device adjacent to the top of the guide post is critical.

Thus, it is typically necessary to make the cut as near as possible to the guide post top to minimize the remaining stub of the exposed guideline. This is necessary to facilitate attaching a new guideline with a latch mechanism.

In addition, the breaking of the guideline is randorn and unpredictable. The break might occur high above the guide post, resulting in a very long, limp pigtaii. Often in such cases, the A primary object of the invention is to provide a remotely actuable cutting assembly for broken, underwater guidelines which can be accurately guided to the top of a guide post and to sever the broken guideline therefrom immediately adjacent the top of the guide post.

Another object of the invention is to provide such a cutting assembly that can accurately sever a broken guideline no matter what configuration the guideline takes.

Another object of the invention is to provide such a cutting assembly which is light in weight easy to store and is simple to manufacture and use.

According to one aspect of the present invention, there is provided an apparatus for remotely cutting a broken guideline extending from an underwater guide post, comprising a frame, a clamping mechanism coupled to the frame for releasably clamping the frame to a guide post in a predetermined location on the guide post, a cutting mechanism coupled to the frame above the clamping mechanism for cutting a broken guideline from a guide post to which the apparatus is clamped, and a remotely actuable power device coupled to the cutting mechanism for actuating the cutting mechanism to cut the broken guidelines from the guide post.

According to a further aspect of the present invention, there is provided an apparatus for remotely cutting a broken guideline extending from an underwater guide post, comprising a frame, a clamping mechanism coupled to the frame for releasably clamping the frame to a guide post in a predetermined location on the guide post, a cutting mechanism coupled to the frame and comprising a pair of opposed, pivotable cutting jaws for cutting a broken guideline from a guide post to which the apparatus is clamped, and a remotely actuable power device coupled to the cutting mechanism for actuating the cutting mechanism to cut the broken guideline from the guide post.

Advantageously, the remotely actuated power device comprises a hydraulic power-device with a U-shaped driver coupled to the frame for slidable movement into engagement with the cutting jaws to pivot these jaws into a cutting action. The two cutting jaws pivot about a common axis and resemble a pair of scissors without handles. When lowering the cutting assembly, the cutting jaws are open, thereby presenting a profile allowing each maneuvering past the broken guideline. As the cutting jaws pivot to the closed position, they embrace and enclose the broken guideline, guiding it to the area on the jaws where actual cutting takes place as the jaws totally close.

The cutting jaws and the clamping mechanism are spaced apart so that the lowermost part of the cutting jaws is immediately adjacent the top of the guide post when the clamping mechanism clamps the frame to the guide post in the predetermined location on the guide post. This is accomplished by having the clamping mechanism releasably received in an annular groove on the outside of the guide post. The clamping mechanism comprises a pair of opposed clamping jaws located below the cutting jaws. These clamping jaws are first engaged with the guide post below the annular groove and then are moved upwardly along the guide post into the groove. A pair of pivotable loom jaws are also provided above the cutting jaws to guide the assembly on the guide post and to push away from the assembly any portion of the guideline extending along the side of the guide post.

According to another aspect of the present invention there is provided a method for remotely cutting a broken guideline which extends from the top of an upright underwater guide post, comprising the steps of lowering a cutting apparatus having a movable cutting mechanism from the surface of the body of water to a location below the top of the guide post, slidably connecting the cutting apparatus to the guide post, raising the cutting apparatus along the guide post to a predetermined location on the guide post, and remotely actuating the cutting apparatus to cause the movable cutting mechanism to move across the top of the guide post and sever the broken guideline immediately adjacent to the top of the guide post.

A specific embodiment of the present invention and modifications thereto will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the cutting assembly being lowered towards an underwater guide post having a broken guideline extending therefrom; Figure 2 is an enlarged perspective view of the cutting assembly, guide post and guideline shown in Figure 1; Figure 3 is a perspective view similar to that shown in Figure 2 except that the clamping jaws have engaged the guide post and the loom jaws have encircled the guide post;; Figure 4 is a perspective view similar to that shown in Figure 3 except that the cutting assembly has been raised upwardly so that the clamping jaws are received in an annular groove on the guide post and the cutting jaws are at a position to sever the guideline immediately adjacent the top of the guide post; Figure 5 is a perspective view similar to that shown in Figure 4 except that the cutting jaws have been actuated to pivot across the longitudinal axis of the broken guideline; Figure 6 is a fragmentary top plan view of the cutting assembly with the loom and cutting jaws in the opened position and the clamping jaws in the closed position; Figure 7 is a fragmentary bottom plan view of the cutting assembly with all of the jaws in the opened position; Figure 8 is a fragmentary side elevational view of the cutting assembly in longitudinal section taken along lines 8-8 in Figure 6;; Figure 9 is a front elevational view of the cutting assembly with all of the jaws in the opened position; Figure 10 is a top plan view in section taken along lines 10-10 in Figure 9 showing the cutting and clamping jaws in the opened position and the drive adjacent the cutting jaws; Figure 11 is a top plan sectional view similar to that shown in Figure 10 except that the clamping jaws have been closed around the annular groove in the guide post, the driver has been slidably moved into engagement with the cutting jaws and the cutting jaws have been pivoted to sever the broken guideline from the guide post; Figure 12 is a front elevational view of the apparatus shown in Figure 1 1; Figure 13 is a perspective view of the lowering assembly for the cutting assembly including a central spool and a pair of guide arms;; Figure 14 is a side elevational view in section taken along line 14-14 in Figure 13 with the addition of the spindle located in the spool and coupled to the handling string and the cylindrical support; Figure 1 5 is a side elevational view in longitudinal section of the guide post with the bushing received therein; Figure 1 6 is a top fragmentary view of two modified clamping jaws having shearable removable inner portions; Figure 1 7 is a side elevational view in section taken along line 1 7-17 in Figure 16 of one of the jaws; and Figure 1 8 is a side elevational view similar to that shown in Figure 1 7 except that the inner portion of the jaw has been released, by severance of shear pins, from the outer portion due to upward movement of the outer portion.

Detailed Description of the Invention As seen in Figure 1, the cutting assembly 10 in accordance with the invention is intended to sever a broken guideline 11 from the upright, underwater guide post 12. This guide post together with three other upright guide posts 13, 14 and 1 5 are interconnected by four horizontal beams 1 6-1 9, which together form an underwater permanent guide base 20 for oil or gas exploration or production. With the guide base 20 located on the seabed, there are three other guidelines 21-23 extending upwardly respectively from guide posts 13-1 5. These guidelines are connected at their top to a platform or suitable vessel at sea level. In addition to the guide base, guidelines can extend from a blow-out preventer stack and a lower riser package.

To lower and raise the cutting assembly 10 relative to the guide base 20, a cylindrical support 24 is carried by the cutting assembly 10 and is internally threaded to receive external threads on a spindle 30 which is in turn threadedly coupled to a handling string of interconnected pipes 25. To stabilize and guide the cutting assembly 10, the spindle 30 is rotatably received in a spool 42 which carries two horizontal arms 26 and 27.

These arms extend outwardly from the spool 900 apart and have shackles 28 and 29 coupled respectively at their ends, these shackles slidably receiving, respectively, guidelines 21 and 23, as seen in Figure 1.

Referring now to Figure 2, the cutting assembly 10 comprises a frame 31, a guiding assembly 32, a cutting jaws assembly 33 and a clamping assembly 34. The guiding assembly 32 includes a pair of opposed guiding or loom jaws 36 and 37; the cutting jaws assembly 33 includes a pair of opposed cutting jaws 38 and 39; and the clamping assembly 34 includes a pair of opposed clamping jaws 40 and 41.

The Frame As seen in Figures 2, 6, 7, 8 and 9, the frame 31 comprises a top plate 44 and a bottom plate 45 having for example I-beams 46 and 47 interposed therebetween on the left and right sides, as best seen in Figure 9, and an end I-beam 48 interposed between the plates near the rear end thereof, as best seen in Figure 8. Thus, I-beams 46 and 47 extend substantially longitudinally of the top and bottom plates 44 and 45, while the end I-beam 48 extends transversely.

These plates and the I-beams are coupled together by five bolts 49-53 passing through suitable apertures in these parts on the left hand side and five other bolts 55-59 passing through these parts through suitable apertures on the right hand side, as best seen in Figure 6. As seen in Figure 9, two shorter bolts 54 and 60 couple the top plate and I-beams 46 and 47 and two other shorter countersunk bolts 54a and 60a couple the bottom plate and these two I-beams.

As seen in Figure 6, the forward end of the top plate 44 has a semi-circular cut-out 61 and as best seen in Figure 7, the forward end of the bottom plate 45 has a semi-circular cut-out 62 therein.

As best seen in Figures 8-11, I-beam 46 has a slot 63 in the forward part to receive cutting jaw 39 when the jaw is open and similarly I-beam 47 has a slot 64 in its forward end to receive cutting jaw 38 when that jaw is open.

The Guiding Assembly Referring now to Figures 6-9, each of the two loom jaws 36 and 37 in the guiding assembly is pivotally coupled to the front of the top of top plate 44 in the same plane by bolts 65 and 66. To pivot the loom jaws outwardly into the open position, a pair of hydraulic cylinders 67 and 68 are pivotally secured to the top plate 44 via bolts 67a and 68a and have, respectively, piston shafts 69 and 70 extending therethrough, the free ends of these shafts having, respectively, two clevis 71 and 72 rigidly coupled thereto and pivotally coupled to the loom jaws respectively via bolts 73 and 74.Biasing the loom jaws towards the closed position shown in Figure 3 are a pair of tension springs 75 and 76 which are coupled rigidly at one end to bolts 73 and 74 rigidly secured to the jaws and at the other end to bolts 77 and 78 rigidly secured to top plate 44. When the hydraulic pressure in cylinders 67 and 68 is relieved, the springs 75 and 76 close the loom jaws.

As seen best in Figures 2 and 3, the inside edges 79 and 80 of the two loom jaws 36 and 37 are arcuate so they encircle the cylindrical guide post 12 in the closed position as seen in Figure 3.

The Cutting Jaws Assembly Referring now to Figures 6, 9, 10 and 11, the cutting jaws 38 and 39 are pivotally coupled between the top and bottom plates along a single bolt 82 passing through suitable apertures in the two jaws and suitable apertures in the top and bottom plates 44 and 45. Jaw 38 is formed from a single member with a semi-circular cut-out 83 near its free end which is bevelled at the bottom to form a cutting edge. Alternately, a replaceable cutting insert can be located in cut-out 83. Jaw 39 is formed of three pieces, either welded together or integrality constructed, including an upper part 84, a lower part 85 and a block 86 rigidly interposed between the upper and lower parts.The upper part 84 has a semi-circular cut-out 87 and the lower part 85 has a semi-circular cutout 88 near their feee ends to coordinate and align with cut-out 83 in jaw 38. As best seen in Figure 9, the end of jaw 38 which is pivotally coupled to bolt 82 is between the upper and lower parts 84 and 85 of jaw 39, the thickness of block 86 being substantially equal to the thickness of jaw 38. As seen best in Figure 8, a pair of bushings 89 and 90 are respectively interposed between, on the one hand, the bottom of the top plate and the top of upper part 84 and, on the other, the top of bottom plate 45 and the bottom of lower part 85.

To close the jaws 38 and 39 there is a remotely actuated power device including a hydraulic cylinder 91 rigidly coupled to the frame, a piston shaft 92 coupled to a piston movable relative to and inside of the hydraulic cylinder and a Ushaped driver 93 rigidly coupled to the shaft and slidable within a cavity 94 in the frame defined between the top and bottom plates and the three I-beams. The driver, as seen in Figure 10, comprises a base 95 and a pair of arms 96 and 97, arm 96 being in a position to contact jaw 38 at its outer tapered edge 98 and arm 97 being in a position to contact jaw 39 at its outer tapered edges 99 upon sliding movement of the driver 93 towards the front of the cutting assembly 10.

The hydraulic cylinder 91 is rigidly secured to the frame 31 via four bolts 100-1 03 which pass through a plate 105 mounted to the end of hydraulic cylinder 91 and into olate 106, which is rigidly secured, such as by welding, to end I-beam 48 at the rear of the cutting assembly. These plates are suitably apertured, as seen in Figure 8, to allow piston shaft 92 to travel therethrough, the end I-beam 48 having an aperture 107 therein, as seen in Figure 8, for passage of the piston shaft 92 therethrough. A threaded end 108 of the piston shaft 92 is received in a suitably internally threaded bore in the base 95 of the driver 93 to rigidly couple these parts together.

As seen in Figures 9-11, the driver 93 is received in cavity 94 and rides along the interior sides of the two opposed left side and right side I-beams 46 and 47.

To open the jaws after they have been closed, a pair of light chains 94a and 94b are tack welded to arms 96 and 97 of the driver and to each of the jaws, as seen in Figures 10 and 11.

The Ciamping Assembly As seen in Figures 6-9, the two clamping jaws 40 and 41 are respectively pivotally coupled to the bottom of the bottom plate 45 via bolts 110 and 111 rigidly secured to the bottom plate. Jaw 40 has a base portion 11 2 receiving the bolt 110 therein via a suitable aperture and a clamping portion 11 3 having a semi-circular cut-out 114, the clamping portion having an upwardly and inwardly tapering frustoconical surface 11 5 extending downwardly from the cut-out 114. As best seen in Figure 9, the surface of the cut-out 114 is semi-cylindrical. The other clamping jaw 41 has a similar mirror image base portion 118, clamping portion 119, cut-out 1 20 and frustoconical surface 121.

As seen best in Figures 6 and 7, a tension spring 123 is coupled between bolts 1 24 and 125 located respectively in recesses 1 26 and 127 in the two clamping jaws 40 and 41. This tension spring 123 tends to bias the clamping jaws 40 and 41 together into the closed position shown in Figure 6.

A brace 128 in the form of an inverted T extends rigidly downwardly from the bottom plate 45 between the base portions 1 12 and 11 8 of jaws 40 and 41, the outwardly extending arms of the brace extending below each jaw, as seen in Figure 9.

As best seen in Figures 7 and 8, a hydraulic cylinder 130 has a piston shaft 1 31 extending outwardly therefrom having a bored end 1 32 pivotally receiving a bolt 133 passing through suitable apertures in jaw 40 to pivotally couple the shaft 1 31 to jaw 40. At the other end of hydraulic cylinder 130 a block 1 34 is rigidly secured to the bottom plate 45, this block having a flange 135 suitably bored and receiving a bolt 136 also passing through suitable bores in the end of she hydraulic cylinder 130. Thus, cylinder 1 30 is pivotally coupled via block 1 34 to the frame 31.

On the other side of the cutting assembly there is a hydraulic cylinder 138 corresponding to clamping jaw 41 as well as a corresponding piston shaft 1 39 extending therefrom having a bored end 140 receiving a bolt 141 to pivotally couple jaw 41 to shaft 139. The other end of hydraulic cylinder 1 38 is similarly pivotally coupled to a block 142 via a bored flange 143 extending from the block and receiving a bolt 144 therein which also passes through suitable bores in cylinder 138.

Block 142 is rigidly secured to the bottom plate 145.

Thus, to move the clamping jaws 40 and 41 to their open position as seen in Figure 7, the piston shafts 1 31 and 1 39 are extended towards the front of the cutting assembly 10. To allow the clamping jaws 40 and 41 to close, the hydraulic pressure in the cylinders is relieved and the spring pressure of tension spring 123 brings the clamping jaws into a closed position, such as that seen in Figure 6. These jaws are locked in the closed position by applying hydraulic pressure to retract shafts 131 and 139 rearwardly of the assembly.

As seen in Figure 9, brace 128 and blocks 134 and 142 extend in the same plane below the jaws in the cutting assembly. Thus, they can be used as feet to support the cutting assembly on, for example, the vessel at sea level.

Alignment of the Jaws Referring again to Figure 2, the cylindrical support 24 is rigidly coupled to a horizontally oriented support beam 146 which is in turn rigidly coupled to a vertically oriented support beam 147.

This beam 147 is in turn rigidly coupled to the top of the top plate 44 of frame 31. As best seen in Figure 3, the longitudinal axis of the cylindrical support 24 will coincide substantially with the longitudinal axis of the guide post 12 carrying the broken guideline 11 and with the central axis of the circle formed by the two arcuate inner edges 79 and 80 of the loom jaws 36 and 37 taken together with the semi-circular cut-out 61 formed in the top plate 44. In addition, the longitudinal axis of the cylindrical support 24 will coincide substantially with the substantially circular opening formed by the closed cutting jaws, as seen in Figure 11 defined by the various cut-outs 83, 87 and 88 in the cutting jaws 38 and 39.

Finally, this longitudinal axis of the cylindrical support 24 coincides substantially with the central axis of the circle defined by the semi-circular cutouts 114 and 120 in the two opposed clamping jaws 40 and 41 in the closed position, as seen in Figure 6.

The Guide Post As seen in Figures 2, 12 and 1 5 the guide post 12 has an annular groove 149 formed near the top thereof with a bushing 1 50 defining the top of the guide post.

7he guide post 12 has a cylindrical outer surface 151 extending into an upwardly and inwardly tapered frustoconical surface 1 52 extending into, at the very top of the guide post an annular, planar surface 1 53. The annular groove 143 begins as a downwardly facing annular surface 155 below cylindrical surface 151 and extends into a reduced diameter cylindrical surface 1 56 which then extends into an inwardly and upwardly tapered frustoconicel surface 157, which extends radially to the cylindrical outer surface 1 58 of the guide post 12. The guideline Ills coupled rigidly to the guide post and extends upwardly out of the center of the bushing 1 50.

As seen best in Figure 2, the bushing 1 5This formed of two semi-cylindrical halves i 60 and 1 61. These halves fit into a central bore 1 62 in the guide post as seen in Figure 1 5. Each carries at least one spring biased locking dog 1 63 in a recess 1 64 therein for coupling into an internal groove 1 65 in the guide post. At the bottom of the bushing, a spear 1 66 is received between and coupled to the two halves. This is accomplished by having an annular flange 167 at the top of tlia spear received in two opposed internal grooves 1 68 and 169 in each half. This flange is located in the grooves as the two halves are piaced together.

The spear has a central bore 1 70 with an enlarged central cylindrical cavity 1 71 at the bottom. The guideline 11 passes downwardly between the two halves, through bore 170 in the spear and has a frayed end received in the cavity 1 71. Molten Babbitt metal 1 72 is poured into the cavity to secure the frayed end of the guideline to the spear.

At the top of the bushing 1 50 is an upwardly and inwardly tapered frustoconical surface 1 73 forming a continuation of surface 1 53 on the guide post and a downwardly facing annular shoulder 1 74 contacting annular surface 1 53 on the guide post to support the bushing on the guide post. The bushing has a planar annular surface 175 at the top.

As seen best in Figure 12, the frustoconical surfaces 11 5 and 121 on the inside of clamping jaws 40 and 41 have substantially the same taper as the frustoconical surface 1 57 in annular groove 149 in the guide post 12. Moreover, the vertical height of the cylindrical surface 1 56 in the annular groove 149 is substantially the same as the vertical height of the semi-cylindrical cut-outs 114 and 120 in clamping jaws 40 and 41. The radius of each cut-out is also substantially equal to the radius of surface 1 56. Thus, when the jaws are closed as seen in Figure 1 2 they will be rigidly received in the annular groove 149.

As also seen in Figure 12, the cutting jaws 38 and 39 and the clamping jaws 40 and 41 are vertically spaced apart so that the lowermost part of the cutting jaws is immediately adjacent the top of the bushing at annular surface 175 when the clamping jaws are received in the annular groove149. Thus, the cutting jaws can sever the broken guideline from the guide post 12 immediately adjacent to the top of the bushing. As also seen in Figure 12, the vertical height between annular surface 175 at the top of the bushing and annular surface 1 55 at the top of groove 149 is substantially equal to the distance between the bottom of cutting jaw 39 and the tops of clamping jaws 40 and 41.

The Lowering Assembly As seen in Figures 1, 13 and 14, the lowering assembly for the cutting assembly 10 comprises the handling string 25, spool 42, arms 26 and 27 having shackles 28 and 29 at their ends, and spindle 30.

The spool is formed as two halves 178 and 179 coupled together by hinges 180 and 181 on opposite sides, hinge 181 being openable to receive the spindle 30 therein. Arms 26 and 27 are rigidly coupled to the spool via pins 1 82, 1 82 and 1 83, 183. Shackles 28 and 29 are releasably coupled to the arms via removable pins 184 and 1 85 so the guidelines can be inserted into the shackles. Spool 42 has a central bore 1 86.

Spindle 30 is cylindrical and has a reducedradius external annular groove 1 87 which is received in and is smaller than the radius of bore 186 in the spool and is defined by upper and lower annular shoulders 1 88 and 189. These shoulders extend above and below the spool and past the diameter of bore 1 86 in the spool to capture the spindle in the spool. This prevents significant relative vertical movement of the spindle and spool but ailows relative rotation.

The top of the spindle has threads 1 90 which threadedly engage threads 191 on the handling tool 25. The bottom of the spindle has threads 1 92 which threadedly engage threads 1 93 on the cylindrical support 24 coupled to the frame.

Thus, by rotating the handling string 25, the cutting assembly 10 can be rotated, via the spindle connection with the handling string, to any desired angular position relative to guide post 12.

Operation To begin the operation of cutting the broken guideline 11, the cutting assembly 10 is first lowered from the sea level through the water by lowering the handling string 25 coupled thereto with shackles 28 and 29 being slidably received around the unbroken guidelines 21 and 23. This lowering proceeds from the position seen in Figure 1 to that seen in Figure 2 as the cutting assembly approaches the guide post 1 2. In this lowering sequence, the loom jaws 36 and 37, the cutting jaws 38 and 39 and the clamping jaws 40 and 41 are open as seen in Figures 2 and 7 so the assembly can easily be maneuvered past the broken guideline, be it in a mare's tail or pigtail configuration.By using television monitors, the cutting assembly is advantageously rotated to a position relative to the guide post so that its frame is on the side of the guide post opposite the trailing end, if any, of the broken guideline. This avoids having to cut a double thickness of the guideline.

As the clamping jaws 40 and 41 move below the annular groove 149 in the guide post 12, the hydraulic pressure in cylinders 130 and 138 maintaining these jaws open is relieved so that tension spring 1 23 tends to close the clamping jaws. This is shown in Figure 3 with the clamping jaws being in contact with the outer cylindrical surface of the guide post 12. In addition, the hydraulic pressure in hydraulic cylinders 67 and 68 corresponding to the loom jaws 36 and 37 is relieved so that tension springs 75 and 76 close the loom jaws as seen in Figure 3 around the guide post. This is best accomplished when the loom jaws are below the bushing so that when they close they engage the guide post only and do not also engage a portion of the broken guidelines that may be extending along the side of the post.

Then, the cutting assembly 10 is slowly raised upwardly with the clamping jaws 40 and 41 sliding along the engaging the guide post 12 and with the loom jaws moving along the post and pushing away any interfering portions of the broken guideline. This upward movement continues until the clamping jaws are fully received in the annular groove 149 below bushing 1 50 as seen in Figures 4 and 1 2. The reception of the clamping jaws in this groove prevents further upward movement. The clamping jaws are then locked in the closed position by hydraulic pressure, thereby preventing downward movement.

At this time, hydraulic cylinder 91 is activated to drive piston shaft 92 towards the guide post 12. This results in slidable movement of the driver 93 from the position shown in Figure 10 into engagement with the tapered outer edges of the cutting jaws 38 and 39. This engagement causes the cutting jaws to pivot around their common pivot bolt 82 and sweep the broken guideline 11 therebetween and into the cut-outs 83, 87 and 88 in these jaws. The location of the broken guideline 11 in these cut-outs is seen in Figures 5, 11 and 1 2. Continued pivotal movement of these jaws in a scissoring motion to the fully closed position severs the broken guideline 11 immediately adjacent the top annular surface 175 of bushing 150, as best seen in Figure 12.As seen in Figure 11, the driver 93, which powers the closing of the cutting jaws, provides a large mechanical advantage allowing use of a minimum amount of structural materials and small capacity power components. Thus, as the driver advances, the cutting jaws pivot towards each other and towards a common centerline. The angle between the outer edges of the jaws and this common centerline (which is also the centerline of the driver and its motivating piston shaft 92) steadily decreases, which means that the applied force to the guideline steadily and dramatically increases.

This results in a favorable wedge effect powering the jaws closed and severing the trapped guideline.

In addition, since the cutting jaws approach the top of the guide post from below, the interference posed by the guideline is minimized. Moreover, by initially gripping the guide post, which itself carries the broken guideline, by means of the clamping jaws, probiems of guiding the guideline into the cutting jaws are minimized.

If for some reason, the guideline is not cut on the first attempt, the driver 93 is moved back to the retracted position shown in Figure 10 under the influence of hydraulic cylinder 91 and thereby pulls the cutting jaws open again via chains 94a and 94b for another severing action.

After the guideline is severed, the clamping jaws 40 and 41 are moved to their open position by activation of hydraulic cylinders 130 and 138 and the entire cutting assembly 10 is moved upwardly through the water to the surface by upward movement of handling string 25. Then, a new guideline can be reinstalled on guide post 12 with a very small stub of broken guideline extending above the top of the guide post.

The Modified Clamping Jaws of Figures 16-18 As seen in Figures 16-18, the clamping jaws 40' and 41' are modified from those shown in Figures 1-12 to include inner portions 194 and outer portions 1 95 which are releasably coupled by three shear pins 196, 197 and 198 received in suitable horizontal aligned bores in these portions.

This reieasable connection is provided to protect the cutting assembly and the guide post in case of an abrupt, violent upward movement of the handling string 25 while the clamping jaws are engaged with the guide post. This movement can be caused by violent wave activity, for example.

In such a case, the handling string will move upward and carry the cutting assembly with it, including the outer portions of the clamping jaws which are severed from the inner portions received in groove 149 in the post. This movement and severance is shown when comparing Figures 1 7 and 1 8. Advantageously, the inner portions can be loosely chained by chain 200 to the outer portions so they will not be lost upon severance of the shear pins.

The inner portions 1 94 extend radially outward from the semi-circular cut-outs 114 and 120 in the clamping jaws and are formed as ring segments with frustoconical surfaces at the bottom on the inside as seen in Figure 1 8.

The shear value of the pins is at a high value which is slightly less than the yield point for release of the inverted T brace 128 coupled to the bottom of the bottom plate 45 and supporting the clamping jaws as seen in Figure 9.

While one advantageous embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims. For example, hydraulic cylinder 91 could be vertically mounted on the frame and move the driver horizontally by means of a pair of links pivotally coupled to the frame, to the piston shaft and to the driver.

Claims (29)

1. An apparatus for remotely cutting a broken guideline extending frorn an underwater guide post, comprising a frame, a clamping mechanism coupled to the frame for releasably clamping the frame to a guide post in a predetermined location on the guide post, a cutting mechanism coupled to the frame above the clamping mechanism for cutting a broken guideline from a guide post to which the apparatus is clamped, and a remotely actuable power device coupled to the cutting mechanism for actuating the cutting mechanism to cut the broken guideline from the guide post.

2. An apparatus for remotely cutting a broken guideline extending from an underwater guide post, comprising a frame, a clamping mechanism coupled to the frame for releasably clamping the frame to a guide post in a predetermined location on the guide post, a cutting mechanism coupled to the frame and comprising a pair of opposed, pivotable cutting jaws for cutting a broken guideline from a guide post to which the apparatus is clamped, and a remotely actuable power device coupled to the cutting mechanism for actuating the cutting mechanism to cut the broken guideline from the guide post.

3. An apparatus as claimed in claim 2, wherein the clamping mechanism is coupled to the frame below the opposed cutting jaws.

4. An apparatus as claimed in claim 2 or 3 for use with an upright guide post having a broken guideline extending from the top thereof, wherein the cutting jaws and the clamping mechanism are spaced apart so that the lowermost part of the cutting jaws is immediately adjacent the top of the guide post when the clamping mechanism clamps the frame to the guide post in the predetermined location on the guide post.

5. An apparatus as claimed in any of claims 2 to 4, wherein the cutting jaws are pivoted about a common axis.

6. An apparatus as claimed in any of claims 2 to 5, wherein the power device includes a member engageable with both cutting jaws for pivoting the cutting jaws.

7. An apparatus as claimed in claim 6, wherein the member comprises a driver coupled to the frame for slidable movement into engagement with the cutting jaws to pivot the cutting jaws.

8. An apparatus as claimed in claim 7, wherein the driver comprises a substantially U-shaped member.

9. An apparatus as claimed in claim 8, wherein the U-shaped member has two arms, each engageable with one of the opposed cutting jaws.

10. An apparatus as claimed in any preceding claim, wherein the remotely actuated power device is a hydraulic power device.

11. An apparatus as claimed in any of claims 7 to 9, wherein the power device is a hydraulic power device and comprises a hydraulic fluid housing coupled to the frame, a hydraulic piston received in the housing, and a hydraulic piston shaft coupled to the piston and to the driver.

12. An apparatus as claimed in any preceding claim, wherein the clamping mechanism comprises a pair of opposed, pivotable clamping jaws for clamping the apparatus to the guide post.

13. An apparatus as claimed in claim 12, wherein the clamping jaws are pivotably mounted on the frame.

14. An apparatus as claimed in claim 12 or 13, wherein the clamping mechanism further comprises a hydraulic power device for opening and clamping jaws and springs for closing the clamping jaws.

1 5. An apparatus as claimed in any preceding claim, wherein the clamping mechanism comprises an inner portion for engaging the guide post and an outer portion, the inner and outer portions being releasably coupled.

1 6. An apparatus as claimed in any preceding claim, wherein the clamping mechanism is arranged for slidably mounting the frame on the guide post, the apparatus further including an assembly for lowering the clamping mechanism from the surface of the body of water to a location below the top of the guide post and for raising the clamping mechanism along the guide post to the predetermined location on the guide post, and a mechanism, coupled to the clamping mechanism, for remotely actuating the clamping mechanism into a slidably coupling engagement with the guide post when the clamping mechanism is lowered below the top of the guide post.

1 7. An apparatus as claimed in any preceding claim, for use with a guide post having an annular groove therein, wherein the clamping mechanism is engageable in the groove to define the predetermined location for clamping of the apparatus on the guide post.

18. An apparatus as claimed in any preceding claim, and further including a guiding mechanism, coupled to the frame, for guiding the frame along the guide post.

1 9. An apparatus as claimed in claim 18, wherein the guiding mechanism is located above the cutting jaws.

20. An apparatus as claimed in claim 1 8 or 19, wherein the guiding mechanism comprises a pair of opposed loom jaws pivotally coupled to the frame.

21 h An apparatus as claimed in claim 20, wherein the guiding mechanism further includes a hydraulic power device for pivoting the loom jaws open and springs for pivoting the loom jaws closed.

22. An apparatus for remotely cutting a broken guideline extending from an underwater guide post, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

23. A method for remotely cutting a broken guideline which extends from the top of an upright underwater guide post, comprising the steps of lowering a cutting apparatus having a movable cutting mechanism from the surface of the body of water to a location below the top of the guide post, slidably connecting the cutting apparatus to the guide post, raising the cutting apparatus along the guide post to a predetermined location on the guide post, and remotely actuating the cutting apparatus to cause the movable cutting mechanism to move across the top of the guide post and sever the broken guideline immediately adjacent to the top of the guide post.

24. A method as claimed in claim 23, wherein the remote actuation step is preceded by the step of rigidly clamping the cutting apparatus to the guide post.

25. A method as claimed in claim 23 or 24, wherein the remote actuation step includes sweeping a pair of opposed cutting jaws towards the broken guideline.

26. A method as claimed in any of claims 23 to 25, wherein the remote actuation step includes embracing the broken guideline with a pair of opposed, pivotable cutting jaws.

27. A method as claimed in any of claims 23 to 26, wherein the raising step is accompanied by the step of outwardly deflecting any interfering portions of the broken guideline extending along the side of the guide post.

28. A method as claimed in any of claims 23 to 27, wherein the apparatus used in the method is an apparatus as claimed in any of claims 1 to 22.

29. A method for remotely cutting a broken guideline which extends from the top of an upright underwater guide post, substantially as hereinbefore described with reference to the accompanying drawings.