US3179176A - Method and apparatus for carrying out operations at underwater installations - Google Patents

Description

April 20, 1965 B. GOEPFERT 3,179,176

METHOD AND APPARATUS FOR CARRYING OUT OPERATIONS AT UNDERWATER INSTALLATIONS a Filed Sept. 18, 1963 f s Sheets-Sheet 1 It E a F,

INVENTOR'.

B. L. GOEPFERT BY: H -a HIS AGENT Apr 20, 1965 GOEPFERT 3,179,176

METHOD AND APPARATUS FOR CARRYING OUT OPERATIONS AT UNDERWATER INSTALLATIONS Filed Sept. 18, 1963 5 Sheets-Sheet 2 as I040 as e -n I 77 no 4 as v FIG. 5

INVENTOR:

B. L. GOEPFERT HIS AGENT April 20, 1965 B. GOEPFERT 3,179,176

METHOD AND APPARATUS FOR CARRYING OUT OPERATIONS AT UNDERWATER INSTALLATIONS Filed Sept. 18, 1965 s She tsSheet 3 I NVENTOR:

B. L. GOEPFERT United States Patent 3,179,176 ME'IHQD AND APPARATUS FUR CARRYENG GUT OPERATIONS AT UNDERWATER IN- STALLATEONE Benjamin L. Goepfert, West Covina, Calif., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Sept. 18, 1963, Ser. No. 3il9,627 11 Claims. (Cl. 166-46) This invention relates to operations to be carried out at underwater installations, and pertains more particularly to a method and apparatus for use in developing oil fields wherein offshore wells are drilled in earth formations lying below a body of water and wherein wellhead equipment of the well, production facilities or manifolding stations, storage tanks, etc., are positioned below the surface of the water. The invention is further concerned with a method and apparatus for manipulating equipment in the vicinity of, or which form components of, an underwater installation, such for example, an underwater wellhead.

A relatively recent development is the drilling of oil and gas well at offshore locations where the wellhead assembly and other related production equipment are positioned at a substantial distance below the surface of the water, or on the ocean floor. 'During the drilling and completion of a well of this type, suitable provisions are made for maintaining contact between the vessel on the surface of the water and the underwater wellhead, as by means of a plurality of guide lines, or one or more elongated pipe strings. Using guide lines or a pipe string between the vessel and the ocean floor, the well may be drilled and all the necessary equipment lowered into place on the top of the wellhead or other underwater installations. the well has been completed, the guide lines extending to the vessel are disconnected from the vessel and either dropped to the ocean floor, secured to a buoy which marks the location of the well, or disconnected from the well and pulled back to the surface.

More recently, however, methods and apparatus have been developed for carrying out. operations at underwater wellheads or other installations without the use of guide lines extending between a vessel on the ocean surface and the installation on the ocean floor. A system for carrying out underwater operations without the use of guide lines makes use of a remotely-controlled manipulator device adapted to move through the body of water and be temporarily secured to or positioned adjacent the underwater wellhead or other installations while being movable thereon and/ or therearound for carrying outthe various operations of setting, adjusting, connecting or disconnecting of the various components or associated equipment of the underwater installation. One such method and apparatus for carrying out underwater operations is disclosed in US; Patent No. 3,099,316.

Presently developed underwater manipulator devices are generally provided with suitable propulsion means for propelling them through the water, sonar apparatus for locating a well, lights for lighting the work area, a television camera for observing the work area, and a telescoping extendible arm provided at its outer end with a tool, such for example as a wrench socket, for carrying out a specific operation on an underwater installation. In using the underwater manipulator device, it is normally lowered from a vessel on the surface by means of a support and electrical transmission cable to the approximate depth of the underwater installation. Suitable propellers on the manipulator device cause the manipulator device to be propelled through the water and it is directed by an operator to a position adjacent to or on the underwater installation. During these operations, the operator on the vessel at the surface follows the movement of the manip- When attain Patented Apr. 20, 19%5 ulator device by its sonar and television camera which may have a range of about 30 feet.

However, it has been found that in certain waters and in certain-locations, it is most diificult and often impossible to position the underwater manipulator device accurately with regard to an underwater installation. These difficulties arise from the water being very murky and/ or ocean floor currents being present which hinder the proper placement of the manipulator device. In using the manipulator device in a locality such as the Cook Inlet on the coast of Alaska, the volcanic silt on the ocean door was constantly stirred up by ocean floor current so that the television camera of the manipulator device had a very limited range. In addition, currents from 6 to 8 knots were encountered which could not be adequately overcome by the limited power propulsion means of a manipulator device so that it would be impractical to move the manipulator device against the current to a position adjacent an underwater wellhead.

It is therefore a primary object of the present invention to provide a method and apparatus for carrying out operations at underwater installations wherein the visibility around the installation is low.

Another object of the present invention is to provide a method and apparatus for carrying out operations at underwater installations which are positioned in areas where substantial river or ocean floor currents exist.

A further object of the present invention is to provide a method and apparatus whereby an underwater manipulator may be positioned at an underwater installation while minimizing a possibility of entangling the lowering line or power transmission line to the manipulator device with anyother underwater apparatus.

A still further object of the present invention is to provide a method and apparatus whereby an underwater manipulator may be lowered from a vessel on the ocean surface to a position near the ocean floor which is offset to one side of the underwater installation in a manner whereby the manipulator device may be subsequently moved laterally so that at least one element of the underwater manipulator engages at least one portion of the underwater installation.

Still another object of the present invention is to provide a method and apparatus for installing a pair of guide lines between a vessel on the ocean surface and an underwater well installation on or near the ocean floor.

A further object of the present invention is to provide apparatus for selectively connecting or disconnecting an underwater manipulator device to one or more guide elementsextending between the ocean floor and the surface, preferably in an offset position from the center line of'the underwater installation.

A further object of the present invention is to provide a remotely-controlled manipulator device adapted to move through a body of water and betemporarily secured to an underwater wellhead while being movable therearound for carrying out any of the various operations of setting, adjusting, connecting, or the disconnecting of a wellhead assembly, components, or associated equipment thereof such as flowlines.

These and other objects of this invention will be understoodfrom the following description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view illustrating the operation of lowering an underwater manipulator device from a vessel on the ocean surface down along a guide element anchored to a base member at an offset position from the nipulator device as having guide means adapted to engage an aligning post at the bottom of a guide cable;

FIGURE 3 is a longitudinal diagrammatic view of another form of the top of a wellhead assembly as shown in FIGURE 1;

FIGURE 4 is a diagrammatic view illustrating the operation of lowering guide lines from a vessel to the surface of the ocean, said lowering being carried out by an underwater manipulator device having the lower ends of the guide lines releasably secured thereto for installing them at an underwater installation;

FIGURE 5 is a diagrammatic view illustrating the operation of lowering an underwater manipulator device along an offset guide line to a position an underwater well assembly and subsequently propelling the manipulator to a position adjacent the well assembly;

FIGURE -6 is a longitudinal view taken partially in crosssection illustrating a production wellhead assembly positioned on the ocean floor and surrounded by guide columns with a manipulator device movably positioned on the wellhead assembly;

FIGURE 7 is a plan view of the wellhead assembly and manipulator device of FIGURE 6;

FIGURE 8 is a fragmental bottom view of a manipulator device provided with a pair of guide arms attached thereto for engaging a guide element;

FIGURE 9 is a side view, taken partially in cross-section, of the lower guide arm of FIGURE 8;

FIGURE 10 is a bottom view of a fragmental portion of an underwater manipulator device showing another form of guide arm;

FIGURE 11 is a bottom view of an underwater manipulator device illustrating a pair of dimetrically-positioned guide arms which are adjustable in a horizontal plane; and,

FIGURE 12 is a bottom view of another form of an underwater manipulator having a pair of guide arms extending in a spaced side-by-side arrangement from one side of the manipulator device.

Referring to FIGURE 1 of the drawing, a drilling barge,

. vessel or platform 11 of any suitable floating or floatable type is illustrated as floating on the surface of the water 12 while being substantially fixedly positioned over a preselected well location by being anchored to the ocean floor 12 by anchor lines 14 and 15 running to anchors (not shown) or by dynamic positioning equipment well known-to the art. Equipment of this type may be used when carrying on well drilling operations or well workover operations in water varying from about 100 to 1500 feet or more in depth. The barge or vessel 11 is equipped with a suitable derrick 16 containing a fall line system 17 (FIGURE 4). The vessel 11 is also provided with other auxiliary equipment needed during well operations, such for example as a rotary table positioned on the operating deck, a hinged slip-and-spider assembly, suitable hoists, constant-tension winches, etc.

In the event that workover operations have to be carriedout on previous drilled and/or producing well, the exact position of the underwater well is known on a map and a vessel 11 may be positioned over the wellhead assembly in any suitable manner as by the use of the shoran or of a similar position-finding system well known to the art.

The underwater wellhead structure illustrated in FIG URE 1 is similar to that which is assembled during the drilling and completion of an underwater well by one well known method. The wellhead assembly includes a largediameter conductor or foundation pile Zll which is secured in the well by means of cement 21. The upper end of the wellhead assembly has a casing head 22 closed by a production bonnet 23 on which are mounted master valves 24. A production T 25 above the master valves 24 is adapted to receive a pair of flow- lines 26 and 27. Swabbing valves 28 are mounted above the production T 25 and the top of the well is closed by means of a lubricator barrel 29 and a plug 30. The top of the plug 30 is provided with a fishing head 31 by which it may be readily removed.

Fixedly secured to the foundation pile 20 near the top thereof are one or more tracks 32 and 32a which may extend around the foundation pile while being positioned outwardly thereof. As shown in FIGURE 5, the tracks 32 and 32a are adapted to receive and hang therefrom an underwater manipulator device which is self-propelled at least in a horizontal direction through the water to engage the track.

The manipulator device, generally represented by numeral 35, may be of any suitable type known to the art, one form being shown in US. Patent No. 3,099,316. The manipulator device comprises a body member 36 having means such as wheels 37 for securing it to the wellhead assembly, that is, to the track 32 in this particular illustration (FIGURES l and 5). The wheels 37 are preferably actuated by motor means operatively connected to the wheels and positioned either inside or outside of the body member 36. Additionally, the body member 36 is preferably provided with a pair of idler rollers 38 mounted on an outwardly-extending frame 39 so as to contact the outer surface of the foundation pile 20, as shown in FIG- URE 5, when the drive wheels 37 are hung on the track 32. Alternatively, the rollers 38 may be powered to make friction contact with the outer surface of the foundation pile todrive the manipulator device 35 around the wellhead assembly. I

A portion of the body member 36 is arranged for upward extension therefrom, preferably in the form of a telescopic arm 40 which is vertically extensible. Mounted on the top of the telescopic arm of body portion 40 is a laterally-extending cylinder 41 having a telescoping arm 42. extendible outwardly therefrom. The lateral arm 42 is provided with a rotatable wrench head 43 that is power operated by suitable motor means mounted in the arm 42 or in the cylinder 41, preferably in the rear portion 44 thereof. A television camera 45 and suitable lights 46 are mounted on top of the manipulator device 35 on a poweractuated light swivel-and-tilting mechanism 47, while the television viewing screen (not shown) is positioned on the vessel 11 of the surface.

The manipulator device 35 may be suspended on a hook 5% having a weight-supporting and power and control signal transmitting cable 51 attached to its upper end. Thus, power and control signals for operating the manipulator device and its associated equipment are sent down the cable 51 from the vessel 11 while the television signals are returned up the cable to the vessel.

At the same time the manipulator device 35 may be lowered from a vessel by means of the cable 51 and its hoist to any selected level in the water. For moving the manipulator device 35 laterally at the end of the cable 51, the manipulator device is provided with suitable propulsion means, such for example as motor-driven propellers 52 which are mounted outboard of the body member 36 on the bottom or at least two sides thereof. Instead of motors and propellers, fluid jets and pumps may be employed. At least a portion, of the body member 36 may form a void chamber which may be selectively flooded by controls at the vessel 11 for adjusting the buoyancy of the manipulator device 35. If additional buoyancy is desired, suitable buoyancy tanks may be se-' cured to the weight-supporting cable 51, or to the manipulator body 36.

As an aid in positioning the manipulator device 35 of FIGURE 1 on or adjacent an underwater installation, for example an underwater wellhead, the manipulator device 35 makes use of a suitable guide system extending between the vessel 11 on the ocean surface 12 and the ocean floor 13. In the event that the manipulator device 35 is not provided with lateral propulsion means such as pro pellers 52, an auxiliary guide system is essential for lowering the manipulator device into alignment with the unbase plate 54.

derwater installation. As shown in FIGURE 1 the foundation pile is provided with a laterally-extending base plate 54 shown as being positioned on the ocean floor 13. One or more vertically extending guide columns 55 and 56 (FIGURES 1 and 4) which are rigidly mounted on the The guide columns 55 and 56 are positioned at an offset position from the axis of the well or underwater installation and may be equidistant therefrom, as illustrated in FIGURE 4.

The guide columns 55 and 56 are preferably flared at their upper end to form cone-shaped flanges 53 and 59. The guide columns 55 and 56 may be tubular and are provided with longitudinal slots 61 (FIGURE 1) extending downwardly from the open upper end thereof to a distance sufficient to allow equipment to be lowered onto the underwater installation, or to a position offset therefrom.

Extending upwardly from each of the guide columns 55 (FIGURE 1) is a guide cable 62 which is normally centrally located within the guide column and is prefer ably of a diameter slightly larger than the slot 55 of the guide column, or is equipped with spools or beads 65 (FIGURES 1 and 1A) so that the cables cannot come out of the slot. The lower end of the cables 62 are preferably releasably anchored in the guide column 55 near the lower end thereof. As shown in FIGURE 1, a hold-down shoe 66 is preferably provided in and fixedly secured to the inner surface of each guide column for anchoring a latching mechanism 67, attached to the lower end of the cable 62, for securing it therein. A weight bar may be positioned above the latching mechanism 67, if desired, so that the latching mechanism will drop through the hold-down shoe 66.

In order to make use of the guide system, the manipulator device 35 is provided with one or more guide arms 68 and 69 (FIGURE 4) with cylinders having frustoconical end portions, commonly known as guide cones 769 and 71, and being attached to the outer ends of the arms. The guide cones 7b and 71 are of a diameter slightly less than the inner diameter of the guide columns 55 and 56. The cone-shaped flanges 58 and 59 at the top of the guide columns 55 and 56, serve to align the guide cylinders 74 and 71 as they move downwardly into the guide columns or tubes. Each of the guide cylinders 78 and 71 is provided with a vertical hole therethrough so that the diameter is slightly larger than the guide cables 62 and 63, thus allowing the guide cones or cylinders to pass freely along the cables and rest within their respective guide columns. The latching mechanisms 67 at the bottom of each cable 62 may be provided witha pair of outwardly-extendible latching dogs 72 which are designed to engage the hold-down shoe 66 (FIGURE 1) in the guide column 55.

The guide lines 62 and 63 (FIGURES l and 4) may be originally installedwhen the base plate 54 and guide columns 55 and 56 are positioned on the ocean floor, or they may be subsequently installed as shown in FIGURE 4. This figure illustrates diagrammatically a manipulator device being lowered from the vessel ill at the surface of the ocean 12 by means of the cable 51. The two guide cables 62 and 63 are being lowered from the vessel at the same time and are being maintained in a relatively taut manner so that they do not become entangled with underwater equipment. The latching mechanisms 67 on the lower ends of the guide lines 62 and 63 are carried by the guide arms 63 and 69 at the outer ends thereof so as to position them in axial register with the tops of the guide columns 55 and 56. When the guide mechanism 67 has beenlowered into the top of the guide columns 55 and 56, the guide arms 63 and 69 aredisengaged from the guide cables allowing the latching mechanism 67 to drop into and become latched on the hold-down shoe 66 (FIGURE 1) in each of the guide columns 55 and 55.

Thus, a method is providedfor carrying out operations at an underwater installation from an operational platform or vessel 11 having at least a portion thereof positioned above the surface of the water. The method in-' cludes the steps of establishing a flexible guide connection between the platform and the underwater installation at a point offset laterally from the center line of the installa tion and then slidably connecting to the ilexible guide connection an underwater manipulator device having an extendible action head or arm free at all times to engage the underwater installation. tor device is moved down along the flexible guide connection to a fixed vertical level adjacent the underwater installation at which point the work or action head of the manipulator device is extended into engagement with at least a portion of the underwater installation. While the apparatus of the present invention has been described with regard to FIGURE 1 as having a wrench socket, at the end of the extendible arm 42, it is to be understood that any other suitable type of action head can be employed instead of the wrench head, such for example as a boring tool, a milling tool, a clamping arm, a pipe-connecting device, etc.

In FIGURE 1, the manipulator device 35 is illustrated as being lowered along the guide line 51 to a position adjacent the wellhead so that the action head or socket wrench 43 is in the vicinity of the wellhead component to be engaged. By raising or lowering the telescoping arm 7 4i vertically and/or by extending the wrench head 43 tioned at a fixed level on one of the tracks 32 or 32a of the wellhead, as shown in FIGURE 5. If it is desired to move the manipulator device 35 (FIGURE 1) to a positionon the track 32 of the wellhead, the propulsion unit 52 of the manipulator device would be started when the 7 wheels 37 of the manipulator device were just opposite and just above the track 32 so that the entire manipulator device could be propelled, together with the guide cables 62. and 63, forward to a position against the wellhead so that the wheels 37 would seat on the track 32. The arms 68 and 69 (FIGURE 4) would then be disconnected from the guide cables 62 and 63 in the event that it was desired to move the manipulator device around the track 32. However, in some circumstances the underwater wellhead is designed so that all of the valves or other components to be adjusted or manipulated by a manipulator device are arranged in a single vertical line or at least in a closely-spaced arrangement, as shown in FIGUREB, so that it would not be necessary to move the manipulator device 35 on or around the track 32 or disconnect it from the guide cables 62 and 63. As shown in FIGURE 3, each valve 24 is provided with an outwardly-extendingstem 73 adapted to be engaged and actuated by the wrench head 43 of the manipulator device 35 (FIGURE 1).

As a guide for positioning the manipulator device 35 at a certain level on the guide cable 62, for example, so

that an operator knows the wrench head is in the vicinity of the component to be moved or that the wheels 37 are in the vicinity of and above the track 32 to be seated on, the cable 62 and/ or other guide cables may be provided with one or more beads or stop elements 65 (FIG- URE 1A) of a size greater than the vertical opening through the guide cylinder 79 at the end of the guide arm 68 (FIGURE 4). Thus, by lowering the manipulator device 35 of FIGURE 1 until the guide cylinder. of cone 76 engages the stop button 65, it would be known that the support wheels 37 of the manipulator device 35 are oppo.

site and just above the track 32. When it was desired to lower the manipulator device further on the guide cables 62 and 63, cylindrical elements 7t and 71 of the hinged or split type would be opened slightly so that they could The underwater manipula- 7 pass the stop element 65 (FIGURE 1) and be lowered to the next stop element.

Instead of employing guide columns 55 (FIGURE 1) adjacent the underwater installation, one or more guide posts 74 (FIGURE 2) may be employed to engage an aligning sleeve 75 carried in a fixed or extensible manner at the end of a guide arm 76, with a single sleeve 75 and a single arm 76 being employed. The propulsion means 52 may be directed in a manner so that the manipulator device can swing in an arc about the aligning post 74. Thus the manipulator device would have a greater area of operation without ever leaving the guide cable 77, or its post 74. As shown in FIGURE 4, the guide cables 62 and 63 are preferably secured at the top to the vessel by means of constant-tension hoists 78 and 79.

In FIGURE 5, a drilling wellhead assembly is shown as being secured to a foundation pile 20 which is mounted in turn on a base plate 80 by means of a ball-and-socket joint 81. One or more guide lines 82 are secured at their lower end to one or more anchor rings 83 fixedly secured to the base plate 80. The wellhead assembly of FIGURE differs from that shown in FIGURE 1 in that the wellhead includes a drilling bonnet 84, blowout preventers 85 and 86, a quick-disconnect coupling 87, and a marine conductor pipe 38 extending to the vessel 11 of the surface end through which a drill string 89 extends. If the guide line 82 is anchored too close to the foundation pile 20, a manipulator device 35, lowered down along the guide cable 82, might accidentally contact an overhanging piece of apparatus, such as blowout preventers 85 to cause damage either to the preventers or to the manipulator device 35. Thus by having the guide cable 82 anchored at a considerably offset position from the axis of the well, the manipulator device 35 may be lowered along the guide cable or cables to a position at a selected level adjacent the installation. At this time the propulsion unit 52 of the manipulator device would be started so that the manipulator device would be propelled toward the wellhead assembly and seated on the track 32 while the guide cylinder 70 at the end of the guide arm 68 was still connected to the guide cable 32 which is arranged to have some slack in it. Subsequently, the guide sleeve and arm 68 could be disconnected from guide cable so as to move the manipulator device 35 around its track 32. After the necessary operations have been carried out at the wellhead, tension would be applied to the hoisting line 51 at the top of the manipulator device to lift it off its track 32 and back to the vessel 11 with or without reconnecting the guide arm of the manipulator to the guide cable 82 again.

In FIGURES 6 and 7 another form of an underwater wellhead assembly is shown wherein the guide system for the main wellhead components comprises three guide cables90, 91 and 92 positioned in three guide columns 93, 94 and 95,respectively. The production wellhead package is shown as a cylindrical housing 96 having guide arms 97, 98 and 99 extending therefrom to terminate in guide cylinders 106 and 161. The guide cylinder normallyin guide column 95 is cut away so as to show the position of the vertically extending longitudinal slot 102 through the Wall of the guide column 95 in line with the axis of the well. A pair of flowlines 103 and 1134 extend from the production housing. The flowlines are connectible to flowline sections 103a and 104a extending along the ocean floor to a production facility. Suitable remotelycontrolled pipe connectors 105 and 106 are employed to connect the pipe lines together. The flowlines 103a and 104a together with their connectors 165 and 106 are mounted on the guide frame 107 having guide arms 168 and 109 adapted to be aligned in auxiliary guide columns 110 and 111 that are similar in construction but may be shorter than the main guide columns 93, 94 and 95. The auxiliary guide columns 110 and 111 are provided with guide cables 112 and 113, respectively. The production housing 96 is shown as being provided with a series of valve stems 114 extending outwardly therefrom, preferably in a vertical line or in a relatively limited area on the side of the production housing directed towards the auxiliary guide cables 112 and 113.

In using the equipment shown in FIGURES 6 and 7, the underwater manipulator device 35 would be lowered down the auxiliary guide cables 112 and 113 to a point adjacent the production wellhead housing 96. In the event that the auxiliary guide columns 116 and 111 were higher than the production wellhead housing 96, the guide cylinders '70 and 71 of the manipulator device 35 would enter the guide colums 119 and 111 before the socket wrench 43 of the manipulator device 35 was at a level sufficient to engage the valves 114 of the production housing 96. Thus, with the guide arms 67 and of the manipulator device 35 fixedly positioned against lateral movement within the guide columns 111 and 1111, respectively, the telescoping arm 42 and its socket wrench 43 are extended into contact with the actuatable element or stem of the valve 114. It is thus apparent that the telescoping arm must be of a length suflicient to extend the distance between the manipulator that is positioned in the guide column and 111 and the production wellhead. Instead of providing a telescoping arm of regular length, the auxiliary guide columns 110 and 111 may be moved closer to the axis of the well. However, in certain installations it is desirable to have sufficient space between the auxiliary guide columns 116 and 111 and the production housing 96 so that the manipulator device can be detached from the auxiliary guide line 112 and 113 after reaching the top of the auxiliary guide columns 110 and 111 so that the manipulator device can be lowered onto the track 32 of the production housing. In this manner the manipulator device 35 is free to move around the track 32 for carrying out the necessary well operations. If the valve stems 114 of the production housing are in substantial vertical alignment and directed toward a slot 102 in one of the main guide columns 95, it is apparent that the manipulator device 35 be provided with only a single guide arm disposed in a direction opposite from its telescoping arm 42, which guide arm could pass down along a main guide cable 92.

In FIGURE 8, one form of disconnectible guide arms is shown in its open and closed positions. Each guide arm 116 may be pivoted to the housing 36 of the manipulator device by a pivot pin 117 at the same time an actuating arm 118 is pivoted at a point 119 spaced from point 117 alongthe periphery of the housing 36. The actuating arm 118 is provided with a hydraulic cylinder having a telescoping piston therein which is secured to an extendible arm 121 while providing pressure fluid through hoses 122 and 123. The arm 121 can be extended or retracted to move the guide arm 116 to various positions. The guide cylinder or cone at the end of the guide arm 116 comprises a pair of hinged sections 124 and 125 secured together by pivot pin 126. A second actuating arm 127 and hydraulic cylinder 128 are arranged on the guide arm 116 and secured to one of the hinge sections 125 for opening and closing the section so that the guide arm can be removed from around the guide cable 130. It is apparent that the disconnectible type of guide arms may take many forms and be either mechanically, hydraulically or electrically actuated. In another form of disconnectible guide arm for the manipulator device (FIGURE 10), the sections 131 and 132 of the guide cylinder at the end of the guide arm 133 are pivoted at 134 and are springloaded to a normally closed position, with the sections opening when the piston within the hydraulic cylinder 135 pulls the ends 136 and 137 of the hinged sections 131 and 132, respectively, against the tapered cone 138 to force the ends 136 and 137 apart and open the sections 131 and 132 from around the cable 130.

In FIGURE 11 the manipulator housing 36, looking at it from the bottom, is provided with a pair of guide arms 140 and 141 located diametrically opposite each other but which are movable to selected movable positions as shown in FIGURE 11 by suitable motor 14?, and gear means 143 and 144 carried within the housing 36. Thus, the guide cylinder 145 at the end of the guide arm 141 can be opened and the guide arm moved away from the cable 146, or alternatively, the guide cylinder 14.15 may remain closed around the guide cable and both arms I40 and 141 move to a position shown on dotted lines in FIGURE 11 so as to force the manipulator device 35 away from the guide cables 146 and 146a and toward an underwater well installation without disconnecting the guide arms from the cables.

In another form of the manipulator device, as shown in FIGURE 12, a pair of rigidly fixed and spaced arms 15%) and 151 are secured to the housing 36 of the manipulator and extend therefrom in parallel spaced alignment. Each arm forms a hydraulic cylinder connected to a pump 152 and reservoir 153 within the housing 36. The piston of the cylinder 150 forms an extensible arm 154 carrying at its outer end a split-type of hinged guide cylinder 155 adapted to surround a cable 156. Thus, it may be seen that the manipulator device of FIGURE 12 may slide down guide line and be pushed away from the guide line and toward an underwater installation by applying fluid pressure to the hydraulic cylinders carried within the guide arms 150 and 151. By using underwater manipulator devices in accordance with the present invention, a system is provided for positioning the manipulator devices under overhanging structures or pieces of equipment so as to carry out operations at relatively inaccessible locations at an underwater installation.

In addition, by use of guide lines of the present invention for guiding manipulator devices in place at an underwater installation, the manipulator device is able to be accurately positioned adjacent an underwater installation in very murky waters where the installation could not otherwise be seen by lights and television at any considerable distance. In some cases, it may be advantageous to secure the television camera to the laterally extendible telescoping arm of the manipulator device so as to move laterally with the Wrench head. Further, by use of the apparatus of the present invention, it is possible to position a manipulator device near the wellhead in waters where excessive currents are encountered without the need for requiring extremely large propulsion units on the manipulator device. In some cases it may be desirable to hinge the guide arms 67 and 68 (FIGURE 7) to the manipulator body in a manner such that it may be moved to a vertically extended position as the manipulator device 35 is moved around the track 32.

I claim as my invention:

1. A method of carrying out operations at an underwater installation from an operational platform above the surface of the water, said method comprising the steps of establishing a flexible guide connection between said platform and said underwater installation at a point offset laterally from the vertical centerline thereof,

slidably connecting to said flexible guide connection at said platform an underwater manipulator device having an extendible action head free at all times to engage said underwater installation,

moving said underwater manipulator device down along said flexible guide connection to a fixed vertical level adjacent said underwater installation,

extending said action head of said underwater manipulator device into engagement with at least a portion of said underwater installation, and

moving the underwater manipulator device laterally at said fixed vertical level to a fixed horizontal position next to the underwater installation prior to extending the action head thereof, said lateral movement being substantially along a line extending radially from the vertical centerline of said underwater installation.

2. The method of claim 1 wherein said lateral movement includes extending the connection between said underwater manipulator device and said flexible guide connection.

3. The method of claim 1 including the step of moving the underwater manipulator device together with said flexible guide connection laterally at a selected level adjacent said underwater installation to a substantially fixed position next to said underwater installation prior to extending the action head thereof.

4. The method of claim 3 wherein said lateral movement of said manipulator device and said flexible guide connection comprises propelling said manipulator device laterally through the water. 7

5. The method of claim 1 including the step of moving the underwater manipulator device laterally at said fixed vertical level into engagement with said underwater installation.

6. The method of claim 5 including the step of positioning said underwater manipulator at a fixed vertical level on said underwater installation.

7. The method of claim 6 wherein said step of positioning includes lowering said underwater manipulator onto said underwater installation at a fixed vertical level.

i 8. The method of claim 6 including the steps of disconnecting said manipulator device from said flexible guide connection and moving said manipulator device to a selected location on said underwater installation.

9. The method of claim 1 wherein said flexible guide connection between said vessel and said underwater installation is originally established by lowering said flexible guide connection and securing it to said underwater installation at a point laterally offset from the center line thereof a distance greater than the extendible length of said action head of said underwater manipulator device.

10. The method of claim 8 including the steps of subsequently moving said manipulator device on said underwater installation to a position adjacent said flexible guide connection, connecting said manipulator device to said flexible guide connection and disconnecting it from said underwater installation and subsequently moving said manipulator device up said guide connection to said vessel.

11. The method of claim 8 including the steps of subse-' quently lifting said manipulator device ofl said underwater installation and pulling it up to the vessel.

References Cited by the Examiner UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner.

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