US3168143A

US3168143A - Guide cable system

Info

Publication number: US3168143A
Application number: US206025A
Authority: US
Inventors: Bruce J Watkins
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1962-06-28
Filing date: 1962-06-28
Publication date: 1965-02-02
Anticipated expiration: 1982-02-02
Also published as: GB969743A

Description

Feb. 2, 1965 Filed June 28, 1962 B. J. WATKINS GUIDE CABLE SYSTEM 2 Sheets-Sheet 1 FIG. 2

INVENTOR:

BRUCE J. WATKINS HIS AGENT 2 Sheets-Sheet 2 I l l l l l l l I l I l l I l llW I l I I I I I I I I I lllllllllllllllllllllll INVENTOR:

BRUCE J. WATKINS HIS AGENT Feb. 2, 1965 B. J. WATKINS GUIDE CABLE SYSTEM Filed June 28, 1962 FIG. 3

United States Patent Ofitice 3,168,143 Patented Feb. 2, 1965 3,168,143 GUIDE CABLE SYSTEM Bruce J. Watkins, West Covina, Calih, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed June as, 1962, Ser. No. 206,025 9 Claims. (Cl. 16666.5)

This invention relates to apparatus for use with underwater installations, such for example, as underwater wellhead assemblies, and pertains more particluarly to a guide line system adapted to extend from an operational base above the surface of the body of water to an underwater installation which is located preferably on or near the ocean floor. The present apparatus further pertains to a guide line system for guiding various pieces of equipment, such for example, as well head components or devices, down to a structure on the ocean floor and into accurate alignment with other fittings or equipment already positioned on the underwater installation.

In an attempt to locate new oil fields, an increasing amount of well drilling has been conducted at oifshore locations, such for example, as off the coast of Lousiana, Texas and California. As a general rule, the strings of casing in a well together with tubing string or strings extend to a point well above the surface of the water where they are closed in a conventional manner that is used on land wells, with the conventional wellhead assembly being attached to the top of the casing. Due to the steeply dipping nature of the shore line on the Pacific coast of the United States, there is a relatively narrow strip of ocean fioor under less than 300 feet of water which might be developed economically from platforms employing legs which extend down to the ocean floor. The remainder of the offshore land, in water greater than 300 feet in depth, particularly the area off the southern California coast that includes deep basins potentially as productive as those on shore can be developed economically only by drilling wells from floating vessels and by utilizing relatively recently developed underwater well drilling and completion methods and apparatus wherein the wellhead assembly is positioned at a substantial distance below the surface of the water or on the ocean floor.

One system for drilling and completing underwater wells is described in copending patent application, Serial No. 118,849, filed lune 22, 1961. In the above-identified patent application, a method is described wherein certain of the wellhead components are stripped down or lowered over a small-diameter pipe string extending from the underwater wellhead to the vessel positioned on the surface of the body of water. When the guiding pipe string is fixedly secured at its lower end to the wellhead assembly, this arrangement necessitates the use of a constant tension winch or other suitable meaoh on the vessel at the surface for maintaining the pipe string in tension as the vessel rises up and down with motion of the sea or supporting the pipe string at a fixed point on the vessel and compensating for vessel motion with a telescopic joint. Additionally, the use of a small-diameter pipe string for lowering equipment is not always satisfactory since there is the danger of it breaking as equipment weighing hundreds of pounds slides down over it at the time the pipe string is moved off a vertical line between the vessel and the underwater wellhead. While a stronger pipe of larger diameter could be used as a guide string, its flexibility would be reduced and certain pieces of equipment would not be able to pass down along it because of the small size bore extending through such equipment.

It is therefore a primary object of the present invention to provide a guide apparatus whereby heavy and cumbersome pieces of well drilling equipment or well production equipment may be lowered to or retrieved from a wellhead at the ocean floor.

A further object of the present invention is to provide small-diameter flexible guide apparatus which may be fixedly secured to a vessel on a body of water without providing equipment thereon to compensate for the rise and fall of the vessel with the motion of the sea, as heavy equipment is lowered to or raised from an underwater installation of any type which is positioned a substantial distance below the surface of the water.

Another object of the present invention is to provide apparatus whereby equipment being lowered into place on an underwater installation will be accurately aligned with a cooperating fitting or another piece of equipment so that it may be readily connected thereto from a remote location, such for example, as from a vessel or platform positioned above the surface of a body of water.

A further object of the present invention is to provide a guide system for permitting accurate placement of a piece of equipment in accurate coaxial alignment on the top of an underwater structure positioned at the top of the elongated tubular member.

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

FIGURE 1 is a schematic view illustrating a wellhead assembly positioned on the ocean floor and being provided with a guide line system in accordance with the present invention which extends to a vessel on the surface of a body of water;

FIGURE 2 is a schematic view illustrating a Wellhead assembly positioned on the ocean floor with a drilling head assembly being raised along the guide cable system of the present invention to the fragmental view of a portion of the deck of the vessel shown in FIGURE 1;

FIGURE 3 is a schematic view illustrating a wellhead assembly positioned on the ocean floor beneath a vessel at the surface, with a production head for the well being lowered along the guide cable system of the present in vention; and

FIGURE 4 is a longitudinal view taken in partial cross section illustrating one type of a weight bar adapted to be secured to the guide cable of the present system.

Referring to FIGURE 1 of the drawing, a drilling barge or vessel 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 drilling location, as by being anchored to the ocean floor 13 by

anchor lines

14 and 15 running to anchors (not shown). Equipment of this type may be used when carrying on well drilling operations or well workover operations in water varying from about to 1500 feet or more. The barge or vessel 11 is equipped with a suitable derrick 16 containing

suitable hoist lines

17 and 17a (FIGURE 2). The vessel 11 is also provided with other auxiliary equipment needed during well drilling operations, such for example as a rotary table 18 positioned on the operating deck of the vessel.

The underwater wellhead structure illustrated in FIG- URES 1 and 2 is similar to that which is assembled during the drilling of underwater wells in accordance with the method described in copending patent application, Serial No. 118,849, filed June 22, 1961. The wellhead assembly includes a large-diameter foundation pile 20 which is connected to a large-diameter conductor pipe 21 which extends into a well 22 drilled in the ocean floor 13 and is preferably fixedly anchored therein by means of cement 23. The upper end of the wellhead assembly has a casinghead 24 mounted thereon to which a drilling bonnet 25 is removably secured.

The drilling bonnet 25 forms the lowermost element of the drilling head assembly which includes

blowout preventers

26 and 27 and a marine conductor or large-diameter pipe string 28 which is removably secured to the uppermost blowout preventer 27 by means of wellhead connector 30 of any suitable type. The upper end of the marine conductor 28 is positioned above the surface of the water adjacent the vessel 11.

Fixedly secured to the foundation pile 20 near the top thereof is the track 32 which extends preferably around the foundation pile while being positioned outwardly thereof. The track 32 is adapted to receive and hang therefrom an underwater manipulator device 33 which is selfpropelled at least in a horizontal direction, and is preferably selectively buoyant.

The manipulator device, generally represented by nufneral 33, may be of any suitable type, two of which are shown in copending patent applications, Serial No. 24,558, filed April 25, 1960, and Serial No. 80,275, filed January 3, 1961. The manipulator device comprises a body mem ber 36 having means such as wheels 37 for securing it to the wellhead assembly, that is, to the track 32 in this particular illustration. The wheels 37 are preferably actuated by motor means operatively connected to the wheels and positioned either inside or outside 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 so as to contact the outer surface of the foundation pile 20, as shown in FIGURE 1, when the drive wheels 37 are hung on the track 32. V The wheels 37 or rollers 38 could be powered to make friction contact with the outer surface of the foundation pile 20 to drive the manipulator device 33 around the wellhead assembly.

A portion of the body member 36 is arranged for an upward extension from the body member, preferably in the form of a telescoping arm 40. Mounted on the top of the telescoping arm or body portion 40, is a laterallyextending cylinder 41 having a telescoping arm extending outwardly therefrom. The 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 thereof. A television camera 45 and the necessary suitable lights for making use of it are mounted at the top of the manipulator device 33 on a power actuated light swivel and tilting mechanism 47, while the television viewing screen is positioned on the vessel 11 at the surface.

The manipulator device 33 may be suspended by means of a hook 48 at the end of a weight-supporting and current-transmitting cable 49 attached to its upper end. Thus, power for operating the manipulator device 33 and the associated equipment is transmitted down the cable 49 from the vessel 11 while the television signals are returned up the cable to the vessel.

The guide cable system of the present invention is illustrated in FIGURES 1, 2 and 3 with regard to the operation of removing a drilling head assembly from the top of the wellhead assembly on the ocean floor, and subsequently (FIGURE 3) lowering the production head and flow lines down the guide cable of the present invention into place to be fixedly secured to the casinghead at the ocean floor. The guide cable of the present invention comprises a single cable 51 which may be fixedly secured in any suitable manner to the vessel at the surface of the body of water, as to the lower end of a fixed hoist line 17, as shown in FIGURE 2. The guide cable 51 extends downwardly through the water and into the innermost pipe string or tubing string positioned in the wellhead assembly or other installations located underwater. In FIG- URE 4, the guide cable 51 is shown as being positioned in an inner casing string 52 which has been cemented in an outer casing string 53. If desired, a weight bar 54 may be secured to the lower end of the guide cable 51 especially if the diameter of the casing string or tubular member 52 in which the cable 51 is positionedis substantially larger than the diameter of the cable 51. If desired, one or more seals 55 and 56 may be positioned on the outer surface of the weight bar 54 to provide additional frictional resistance between the outer surface of the weight bar 54 and the inner surface of the tubular member 52. In the event that seals 55 and 56 are employed, or if the diameter of the weight bar 54 is substantially equal to that of the tubular member 52, the weight bar is preferably provided with

fluid passageways

57 and 58 to facilitate passage of fluid by or through the weight bar 54 when the weight bar 54 is lowered into the fluidfilled well.

Check valves

59 and 60 may be employed to close

fluid passageways

57 and 58 on upward movement of the weight bar 54. 7

It is to be understood that the use of a weight bar, as shown in FIGURE 4, is not necessary if the weight of the cable alone is sufficient, especially when the guide cable 51 is positioned in a small-diameter pipe string or tubing string in the well. Thus, it has been found that a substantial length, say 1000 feet or more, of 1% inch cable positioned in a 1 /2 'or 2 inch tubing string in the well supplies adequate weight and frictional resistance to prevent the cable from being pulled out of the well as pieces of equipment are lowered from the vessel at the surface to the Wellhead assembly on the ocean floor. In the event that a very heavy piece of equipment is being lowered along the guide cable 51 fromthe vessel to the wellhead assembly on the ocean floor, the length of the cable in the well tubular member may be increased, say to 4000 feet for example, in order to supply sufficient weight at the end of the guide cable to maintain the upper portion'of cable taut between the vessel and the wellhead assembly. While it is understood that suitable cable coni nector means may be carried by the lower end of the cable to fixedly secure or grip it to the inner surface of the tubular well member in which it is positioned, it is preferred that the cable within the well not be attached to the inner surface of the well tubular member, thereby allowing the cable to move up and down in the well tubular member as the vessel on the surface of the ocean moves up and down with the movement of the water.

In FIGURE 2 the drilling head assembly, including the drilling bonnet 25 and

blowout preventers

26 and 27, is shown as being raised by means of the marine conductor pipe 28, which may be raised through the rotary table 18 on the vessel 11 and fixedly secured therein in a manner well known to the art, as by slips (not'shown) and hung there while the uppermost section 28a of the marine conductor pipe is removed, and set aside. Prior to disconnecting the drilling bonnet 25 from the wellhead assembly, by means of the power wrench 43 carried on the manipulator device 33, the guide cable 51 of the present guide system is lowered down through the marine conductor pipe 28 or any other pipe string extending from the vessel 11 to the wellhead assembly on the ocean floor. It is to be understood that if desired, the marine conductor pipe 28 could be removed independently together with a wellhead connector 30 from the blowout preventer 27 and a smaller pipe string (not shown) could be stripped down over the guide cable 51 and secured to the uppermost blowout preventer 27 to raise the

blowout preventers

27 and 26 to surface in a manner well known to the art.

After the Well is completed, and the necessary tubing strings have been run therein, with the guide cable 5'1 of the present guide system extending into the tubing string, a production head may be lowered from the vessel 11 into place on the wellhead assembly in a manner shown in FIGURE 3 of the drawing. The production head comprises a production bonnet 61 adapted to be secured to the casinghead 24 of the wellhead assembly. Mounted on the top of the production bonnet 61 are

master valves

62 and 63 and swabbing

valves

64 and 65.

Flow lines

66 and 67 are provided with

flow control valves

68 and 69 which are remotely actuated. The lubricator 70 at the top of the production assembly is secured in a suitable manner to a running string 71 by which the production assembly is stripped down over the guide cable 51 to the top of the underwater wellhead assembly.

While the guide system of the present invention has been described in regard to lowering equipment to and from an underwater wellhead assembly, it is to be understood that it provides an excellent guide apparatus for lowering equipment from a vessel on the surface of the ocean to any underwater installation which is provided with an elongated tubular member into which the guide cable of the present system can be positioned or engaged therein. Thus, certain underwater installations used at offshore locations comprise an underwater platform having tubular legs of substantial length which support a platform, say 100 feet under the surface of the water, on which the equipment is mounted. Additionally, the guide system of the present invention could be employed in lowering equipment to underwater oil storage or manifolding facilities which employ substantially vertical elongated tubular members in their construction, such for example, as tubular piles.

I claim as my invention:

1. Apparatus for guiding equipment from an operational base floating on the surface of a body of water to an underwater installation positioned on the ocean floor having at least one elongated substantially vertical tubular member aflixed thereto, said apparatus comprising (1) guide cable means extending between said floating operational base and the underwater installation, said guide cable means having a substantially uninterrupted elongated outer surface between the floating base and the interior of said tubular member of said underwater installation,

(2) the upper end of said guide cable means being secured to said floating operational base,

(3) the lower portion of said guide cable means extending downwardly into said elongated substantially vertical tubular member of said underwater installation and being arranged in sliding engagement therein.

2. The apparatus of claim 1 wherein the portion of the guide cable means extending into said underwater tubular member is of a weight sufiicient to sink into said tubular member and maintain said portion of said guide 6 cable means between the floating base and the underwater installation sufliciently taut to glide any equipment therebetween which may be mounted on said guide cable means.

3. The apparatus of claim 2 including weight bar means carried on the lower portion of said guide cable means, said Weight bar means being of a size to fit Within the underwater tubular member.

4. The apparatus of claim 3 wherein said weight bar means has longitudinal flow passage means therethrough and check valve means in said flow passage means.

5. The apparatus of claim 1 wherein said underwater installation is a well provided with an underwater wellhead having a pipe string depending therefrom.

6. The apparatus of claim 5 wherein said wellhead includes a tubing string positioned therein and depending therefrom for containing the lower portion of said guide cable means.

7. The apparatus of claim 6 wherein said guide cable means comprises a cable of a diameter slightly smaller than said tubing string, the lower portions of said cable being of a length and weight to maintain substantially taut the portion of cable extending between the Wellhead assembly and the floating operational base.

8. The apparatus of claim 2 including guide means slidably engaging said guide cable means and lowering means secured to said guide means, said lowering means being extendible between said floating base to said underwater installation.

9. The apparatus of claim 8 wherein said guide means and said lowering means comprise an elongated string of pipe.

References Cited by the Examiner UNITED STATES PATENTS 1,610,372 12/26 Hansen 6 2,650,068 8/53 Rand 1756 2,665,885 1/54 Gignoux 175-6 2,906,500 9/59 Knapp et al 16666.5

FOREIGN PATENTS 874,178 8/61 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

Claims

1. APPARATUS FOR GUIDING EQUIPMENT FROM AN OPERATIONAL BASE FLOATING ON THE SURFACE OF A BODY OF WATER TO AN UNDERWATER INSTALLATION POSITIONED ON THE OCEAN FLOOR HAVING AT LEAST ONE ELONGATED SUBSTANTIALLY VERTICAL TUBULAR MEMBER AFFIXED THERETO, SAID APPARATUS COMPRISING (1) GUIDE CABLE MEANS EXTENDING BETWEEN SAID FLOATING OPERATIONAL BASE AND THE UNDERWATER INSTALLATION, SAID GUIDE CABLE MEANS HAVING A SUBSTANTIALLY UNINTERRUPTED ELONGATED OUTER SURFACE BETWEEN THE FLOATING BASE AND THE INTERIOR OF SAID TUBULAR MEMBER OF SAID UNDERWATER INSTALLATION, (2) THE UPPER END OF SAID GUIDE CABLE MEANS BEING SECURED TO SAID FLOATING OPERATIONAL BASE, (3) THE LOWER PORTION OF SAID GUIDE CABLE MEANS EXTENDING DOWNWARDLY INTO SAID ELONGATED SUBSTANTIAL-