US3221817A

US3221817A - Marine conductor pipe assembly

Info

Publication number: US3221817A
Application number: US223396A
Authority: US
Inventors: Vries Douwe De; Jr Frank Poorman
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1962-09-13
Filing date: 1962-09-13
Publication date: 1965-12-07
Anticipated expiration: 1982-12-07

Description

Dec. 7, 1965 0. DE VRIES ETAL 3,221,317

MARINE CONDUCTOR PIPE ASSEMBLY Filed Sept. 13, 1962 6 Sheets-Sheet 2 F 2 INVENTORS D. DE VRIES F. POORMAN.JR. BY

THEIR AGENT Dec. 7, 1965 D. DE VRIES ETAL MARINE CONDUCTOR PIPE ASSEMBLY 6 Sheets-Sheet 5 Filed Sept. 13, 1962 INVENTORS 0. DE VRIES R. m J. E N G A u A M R R O H H O H P F Dec. 7, 1965 0. DE VRIES ETAL 3,221,317

MARINE CONDUCTOR PIPE ASSEMBLY Filed Sept. 13, 1962 e Sheets-Sheet 5 IIO INVENTORS F|G.8 D. DE VRIES F. POORMAN,JR.

THEIR AGENT United States Patent 3,221,817 MARINE CONDUCTOR PIPE ASSEMBLY Douwe de Vries, Metairie, and Frank Poorman, Jr., Lafayette, La., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Sept. 13, 1962, Ser. No. 223,396 7 Claims. (Cl. 16666.5)

This invention relates to apparatus for use in drilling, completing and working-over operations in oil and gas wells at offshore locations, and pertains more particularly to apparatus adapted to provide full-flow fluid communication between a vessel at the surface of a body of water and a wellhead assembly positioned on the ocean floor or at a substantial depth below the surface of the water.

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 Louisiana, Texas and California. As a general rule, the strings of casing in a well, together with the tubing strings or string, extend to a point above the surface of the water where they are closed in a conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Recently, methods and apparatus have been developed for drilling and completing wells wherein both the well casinghead, and subsequently the wellhead assembly and casing closure device, are located under water at a depth sufficient to allow ships to pass over them. Preferably, the casinghead and the wellhead closure assemblies are located close to the ocean floor. In order to install well drilling equipment underwater at depths greater than the shallow depth at which a diver can easily operate, it has been necessary to design entirely new equipment for this purpose.

Wells drilled in deep water are generally drilled from vessels of varying designs commonly known as drilling barges, vessels or platforms. Deepwater wells are generally drilled by one of two methods. In one method the string of drill pipe extends downwardly from the drilling barge to the drilling wellhead assembly on the ocean floor which is closed at the top by a circulation head with a flexible hose running from the circulation head back to the surface and to the drilling barge so that drilling fluid may be circulated down the drill pipe, through the drill bit, and thence upwardly on the outside of the drill pipe, out the circulation head and up the flexible hose to the barge again. In the second method, a large-diameter pipe known as a marine conductor pipe is put together and arranged to extend from the drilling wellhead assembly on the ocean floor to the barge on the surface of the water. In the latter method, the drill pipe rotates within the conductor pipe with drilling fluid being circulated down through the drill pipe, through the bit at the bottom thereof, up the outside of the drill pipe and thence upwardly through the annular space between the conductor pipe and the drill pipe, returning to the barge in the conventional way. The present invention is concerned with apparatus to be used in the second method described hereinabove.

One of the problems in drilling underwater wells from floating barges is that of providing suitable means for suspending and/ or securing a marine conductor pipe assembly in movable relationship to the drilling barge so that the barge is free to move up and down with the movement of the water while the marine conductor pipe assembly is fixed against vertical movement while being arranged to be moved laterally in any direction. Some of the presently designed marine conductor pipe assemblies have been provided with buoyancy tanks supplying a positive buoyancy to the marine conductor pipe assembly so that the assembly is vertically positioned in the Patented Dec. 7, 1965 ice water with its lower end locked to an underwater wellhead. A marine conductor pipe or assembly of positive buoyancy has certain drawbacks in that, in the event that the connection between the lower end of the conductor pipe and the wellhead is broken, the conductor pipe would shoot upwardly in the water underneath or adjacent the barge and possibly damage the floating drilling barge or rupture some of its buoyancy tanks.

It is therefore a primary object of the present invention to provide apparatus for supporting a marine conductor pipe assembly adjacent to a barge without the possibility existing of the marine conductor pipe breaking loose from an underwater wellhead and/ or the barge and damaging the barge.

A further object of the present invention is to provide apparatus independent of the barge for supporting the major portion or weight of a marine conductor pipe assembly while the rest of the assembly is supported by the barge itself.

Another object of the present invention is to provide weight-supporting apparatus on a floating drilling barge which may be readily adjusted to support a portion of the weight of a marine conductor pipe assembly as the weight of the portion varies due to changes in drilling operations, such for example, as due to a change in the weight of the drilling mud being circulated through the assembly.

Still another object of the present invention is to provide a marine conductor pipe assembly including apparatus for controlling and/or killing a well from a point above the surface of the water when emergency conditions are encountered in the drilling of a well.

A further object of the present invention is to provide a marine conductor pipe assembly with suflicient flexibility whereby in rough weather a drilling Vessel or barge may move several degrees in any direction off the center line of a well that is being drilled without rupturing the marine conductor pipe assembly.

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

FIGURE 1 is a diagrammatic view taken in longitudinal projection illustrating a floating drilling vessel positioned at the surface of the ocean with an underwater wellhead assembly positioned on the ocean floor;

FIGURE 2 is a diagrammatic view taken in longitudinal projection and in enlarged detail of the lower portion of the drill rig and the upper portion of the marine conductor pipe assembly shown in FIGURE 1;

FIGURE 3 is a cross-sectional view taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a longitudinal view taken in enlarged detail of one of the counterweights or ballast tanks of FIGURE 2;

FIGURE 5 is a cross-sectional view taken along the line 5-5 of FIGURE 4;

FIGURE 6 is a longitudinal view in enlarged detail of one of the buoyancy tanks surrounding the marine conductor pipe of FIGURE 1;

FIGURE 7 is a longitudinal view of the other buoyancy tank shown in FIGURE 1;

FIGURE 8 is a longitudinal view illustrating the manner in which the upper ends of auxiliary pipes running along the outside of the marine conductor pipe are secured thereto;

FIGURE 9 is a cross-sectional view taken along the line 9-9 of FIGURE 8;

FIGURE 10 is a view taken in partial cross section of one form of a pipe guide and support member by which auxiliary pipes may be secured to the marine conductor pipe of the present invention;

. cemented therein.

FIGURE 11 is a plan view of the apparatus in FIG- URE and,

FIGURES 12A, 12B and 12C are longitudinal views adapted to be arranged end to end to show in enlarged detail the marine conductor pipe assembly of the present invention as it is positioned on a wellhead of the ocean floor.

Referring to FIGURE 1 of the drawing, a drilling barge or platform is generally represented by numeral 11.. The drilling barge or platform 11 is of any suitable type preferably one, as illustrated, floating at the surface of a body of water 12 and substantially fixedly positioned over a preselected drilling location by suitable barge positioning means or by being anchored to the ocean floor 13 by suitable anchors 14a and 15a connected to the

anchor lines

14 and 15. Equipment of this type may be used when carrying on well drilling operations in water depths varying from about 100 to 1500 feet or more. The drilling barge is equipped with a suitable derrick 16 as well as other auxiliary equipment needed during the drilling of a well such as a hoist system 17, rotary table 18, etc. The derrick 16 may be positioned over a drilling slot or well which extends vertically through the barge in a conventional manner. When using the equipment of the present invention the slot of the barge may be centrally located or extend in from one edge. However, drilling operations may be carried out over the side of the barge or vessel without the use of a slot, as from a portion of the deck of the barge which is cantilevered out over one end, as is the case in the barge in FIGURE 1.

As shown in FIGURE 2, a portion of the barge deck 20 is cantilvered toward the viewer on

support beams

21 and 22 which are supported by

diagonal braces

23 and 24 from

vertical support members

25 and 26 of the barge. Suspended beneath the cantilevered portion 20a of the barge deck 20 is a craneway made up of

tracks

27 and 28, and intermediate deck 30 and a spider deck 31. The

decks

20a, 30 and 31 are all positioned below the derrick 16 which is provided with an elevated rig floor or operat ing platform 32.

A typical underwater wellhead structure, generally represented by numeral 34 in FIGURE 1, is illustrated as comprising a base member 35 which is positioned on the ocean floor 13 and fixedly secured to a conductor pipe or a large diameter well casing 36 which extends down into a well which has been previously drilled, and is preferably Thus, the base structure or member 35 is rigidly secured to the ocean floor in order to support two or more vertically-extending guide columns 37 and 38 (FIGURE 12C) adapted to receive and guide therein

guide arms

40 and 41, 40a and 41a, and 40b and 41b which are arranged to slide along vertically extending

guide cables

42 and 43. The lower ends of the

guide cables

42 and 43 are anchored to the base structure 35 within the

guide columns

37 and 38, while extending upwardly through the water to the drilling barge 11 where they are preferably secured to constant tension hoists (not shown). If desired, a single guide cable extending between the base structure 35 and the vessel 11 may be employed to position a piece of equipment on the wellhead. Generally, a guide system having at least three guide cables is preferred. However, it is to be noted that wellhead equipment could be lowered from the vessel 11 down to the wellhead by methods other than using the guide cable system illustrated.

Centrally positioned above the base member 35 and fixedly secured thereto, or to the conductor pipe 36, is a well casinghead unit 44 which may be provided with a cement circulation or fluid return line 45 which may be selectively closed by a remotely operated valve 46. The

guide arms

40 and 41 are illustrated as being connected to a wellhead connector unit 47 which may be hydraulically or electrically actuated to connect to the top of the application Serial No. 105,068, filed April 24, 1961. In the above-identified patent application, a wellhead connector 47 is provided with a self-contained electro-hydraulic operating unit which is provided with operating power from an electrical transmission line (not shown) running to the barge 11 at the surface. Alternatively, the wellhead connector could be hydraulically operated by means of a pressure fluid line (not shown) running to the barge 11.

During the drilling of a well, one or more blowout preventers are connected coaxially above the wellhead connector 47. In FIGURE 12C a series of three

blowout preventers

50, 51, and 52 are illustrated as being fixedly secured together and forming a unitary package with the wellhead con-nector 47, which package .is adapted to be lowered onto the casinghead 44 in any suitable manner. Preferably, the combined

blowout preventers

50, 51 and 52 and the wellhead connector 47 are run together into position on the top of the well by being lowered through the water from the drilling vessel 11 by means of a pipe string (not shown), commonly known as a running string, with the lower end of the running string being connected to the uppermost blowout preventer 52 by any suitable coupling or connector which may be similar in form to the wellhead connector 47. During drilling operations the running string is replaced by a larger diameter pipe known as a marine conductor pipe and is represented generally in the drawing by numeral 53.

The various wellhead components, such for example as the wellhead connector 47 and

blowout preventers

50, 51 and 52 may be either hydraulically, pneumatically, or electrically actuatable but are preferably actuatable with each unit being provided with an electro-hydraulic operator unit as described in copending patent application Serial No. 105,068, filed April 24, 1961. Alternatively, the

blowout preventers

50, 51 and 52 could be provided with pressure hoses (not shown) which would extend up through the water to the drilling barge 11.

In addition, the drilling assembly stack of

blowout preventers

50, 51 and 52 on the top of the wellhead connector 47 is provided with one or preferably two small diameter conduits which will be termed hereinbelow as choke and kill

lines

54 and 55, respectively. The choke and kill

lines

54 and 55 are employed to provide means for establishing fluid communication between the drilling vessel 11 and the well during drilling operations after one or more of the blowout preventers 51 and 52 have been closed during an emergency. The choke and kill

lines

54 and 55 are provided with remotely

actuatable valves

56 and 57, respectively, which are actuated through pressure hoses or electrical transmission lines (not shown) which extend to the surface. Since these valves and the blowout preventers and the wellhead connector 47 do not form an essential part of the present invention and are described in detail in the above-identified copending application, they will not be further described here.

A marine conductor pipe assembly is employed in drilling underwater wells in order to establish unrestricted communication with the well in a manner shown and described in US. Patent 2,606,003, which was issued August 5, 1952, to J. M. McNeil]. The marine conductor pipe is of suflicient diameter that a drill pipe and drill bit at the lower end of the drill pipe can be run down through the marine conductor so as to bore into the ocean floor. Thus, the annular space between a drill pipe and the inner wall of a marine conductor pipe forms a full flow passage for return of fluid to the drilling barge together with cuttings removed from the bottom of the well by the bit. Drilling mud would be pumped entirely in the conventional way by means of a pump from the barge down the drill string (not shown), out the drill bit, up the space outside the drill pipe in the well to the wellhead on the ocean floor, and thence upwardly through the casinghead, blowout preventers and up through the marine conductor 53 outside the drill pipe to the barge 11.

The marine conductor pipe assembly, generally represented by numeral 53 in FIGURE 1, is shown in FIGURES 12A, 12B and 12C in greater detail, FIG- URE 12B representing an upward extension of FIG- URE 12C and FIGURE 12A representing an upward extension of FIGURE 12B. It is to be understood however that the overall length of the marine conductor pipe assembly may vary from 100 to 1500 feet or more while the width of the assembly need not become any greater. In order to facilitate handling of the marine conductor pipe assembly of the present invention on a drilling vessel, and to aid in the assemblying or construction of the marine conductor pipe so that it extends from the drilling vessel 11 (FIGURE 1) to the uppermost blowout preventer 52 of the drilling stack (FIGURE 12C), the marine conductor pipe assembly 53 is made up in a number of sections, the pipe sections generally being from to 40 feet long.

The lowermost section of the marine conductor pipe assembly comprises a large diameter pipe 60 having fixedly secured to its lower end a landing head or pipe connector 61 of a size and having a bore to fit telescopically onto and to make a sealing engagement with a landing mandrel 62 which is fixedly secured at its lower end to the uppermost blowout preventer 52, and extends upwardly and coaxially therefrom. If desired, a pipe joint locator 63 may be provided in the conductor pipe assembly above the landing head 61.

Extending upwardly along the large-diameter conductor pipe 60 are at least one and preferably two small-diameter pipes which in this case are extensions of the choke and kill

lines

54 and 55, respectively. It is to be understood that these small-

diameter pipes

54 and 55 are also made up from short pipe sections which are coupled together in any suitable manner, as by screw threads or other couplings, it being preferred that the coupled joints are flush on the outside with the connectors or tool joints having the same outside diameter as that of the pipe. The choke and kill

lines

54 and 55 are aligned with the marine conductor pipe 60 by means of a series of guide and support arms or brackets generally represented in FIGURES 12A, 12B and 12C by numeral 64. One form of a suitable guide and support arm 64 is shown in FIGURES 10 and 11. As illustrated, the pipe support bracket 64 comprises a short section of large-diameter pipe which is split longitudinally and hinged at 66 while being connectible on the opposite side by bolts 67. The internal diameter of the pipe section 65 is equal to the outside diameter of the marine conductor pipe 60 and serves in the way of a clamp. A pair of

diametricallypositioned arms

68 and 69 extend outwardly from the pipe section 65 With small-diameter pipe guides 71 and 72 being fixedly secured, as by Welding to the ends of the

arms

68 and 69. The pipe guides 71 and 72 consist of short sections of small-diameter pipe slightly larger than the choke and kill

lines

54 and 55 so that the pipe guides 71 and 72 are able to slide up and down the

pipes

54 and 55 when engaged around them. For ease in attaching the pipe guides to the choke and kill lines, the pipe guides 71 and 72 also may consist of split pipe sections provided with hinge pins 73, and connector pins 74. Any suitable spacing may be employed between the support arms 64. Generally, a support arm or bracket 64 is positioned above each tool joint or every other tool joint of the marine conductor pipe 60, depending upon the length of the pipe sections of the marine conductor pipe.

As shown in FIGURE 1 and FIGURES 12A and B, the marine conductor pipe 60 is provided with a buoyancy member or chamber in the form of one or more concentrically arranged

buoyancy tanks

76 and 77 which, for ease of handling, are preferably no greater in length than one section of the marine conductor pipe 60. As shown in FIGURES 6 and 7, the

tanks

77 and 76 may be provided with internal reinforcing members 78. The

number and size of the

buoyancy tanks

76 and 77 to be used would naturally depend upon the weight of the marine conductor pipe 60 and the choke and kill

lines

54 and 55 to be supported. The weight of these

elements

54, 55 and 60 in turn depends upon the depth of the water at which a well is being drilled as well as the size of these elements and the material of which they are made. Whatever amount of weight exists to be supported by these buoyancy tanks, it is extremely important, in accordance with the teachings of the present invention, that the buoyancy tanks together with the marine conductor pipe assembly to which they are attached have a negative buoyancy. That is, in the event that the marine conductor pipe assembly broke loose at the blowout preventers, the

buoyancy tanks

76 and 77 would not have suflicient flotation capacity to cause the marine conductor pipe to float to the surface thus obviating any chance of the marine conductor pipe assembly damaging the drilling vessel. It is preferred, however, that the combined buoyancy tanks and conductor pipe assembly have only a slightly negative buoyancy. Thus, the buoyancy tanks are preferably designed so as to support the major portion of the weight of the marine conductor pipe assembly below them.

The remaining weight portion of the marine conductor pipe assembly is supported at the vessel by means of

suitable cables

80 and 81 which are fixedly secured at one end to the upper movable end 82 of the conductor pipe 60. In the particular arrangement of equipment shown the upper end 82 of the conductor pipe 60 is provided with a telescopic joint in the for-m of a section, say 25 feet long, of large-diameter pipe 83 in which a smaller-diameter pipe 84 is mounted for sliding vertical movement through a seal (not shown) carried in the upper end 82 of the conductor pipe. The upper end of the small diameter pipe 84 may be provided with a bumper section 85 and a bell nipple 86 from which a side conduit 87 allows mud to flow to suitable mud tanks (not shown). The bell nipple 86 is concentrically positioned beneath the rotary table 18 and is supported in place together with the small-diameter pipe portion of thei telescopic sub by means of support chains or cables 8 an 9.

As shown in FIGURES 2 and 3 the

cables

80 and 81 which extend from the upper end 82 of the telescopic joint section 8, are lead over suitable sheaves or pulleys. Thus, cable 80 passes over

sheaves

88, 89 and 90 with the opposite end of the cable being connected to a counterweight 91. Cable 81 in turn passes over

sheaves

92, 93 and 94 and the lower end of the cable is secured to the top of counterweight 95.

Cables

80 and 81 may each actually represent a number of parallel cables, depending on the loads imposed.

A preferred form of counterweight is shown in FIG- URES 4 and 5 of the drawing as comp-rising a pair of open-topped tanks, each tank or counterweight 91 (FIGURE 5) being provided with lateral movement limiting means in the form of vertically-arranged oak runners 96 on opposite ends of the tank 95, the runners being adapted to slide vertically along angle-iron guide rails 97 which form an elevator shaft (FIGURE 4) in which the counterweight tank rises and falls as the drilling vessel 11 and support member 25 rises and falls with the motion of the Water, thus enabling a constant tension to be maintained by

cables

80 and 81 on the top of the marine conductor pipe assembly to support that portion of the weight thereof that is not supported by the

buoyancy tanks

76 and 77. The contact surface of the oak runners 96 is kept heavily greased at all times. The counterweight tank 91 (FIGURE 5) is provided with one or more vertical bafl'le plates 98 to reduce the movement of the water laterally in the tanks while the bottom of the plates 98 are provided with openings therethrough (not shown) so that the level of water in the tank '91 can equalize after filling. Each tank is also of the mandrel 62.

provided with a suitable drain port 99 and shut-off valve 100. The oak runners are secured to the outside of the tank 91 by suitable bolts 101 and are replaceable when worn. The end of the cable 81 is secured to the top center of the tank by bolt 102 (FIGURE 4). The vertical length of the elevator rails 97 may be in the order of 20 feet or more depending upon the estimated rise and fall of the drilling vessel 11 and hence the movement of the

counterweight tanks

91 and 95 during drilling operations.

Horizontal cross members

103 and 104 are provided at the lower end of the vertical elevator guide rails 97 so that the

counterweights

91 and 95 can be positioned thereon when not in use and when disconnected from the marine conductor pipe assembly. The amount of tension being applied to the

counterweight cables

80 and 81 by the

counterweights

91 and 95 can be readily adjusted by adding more water to the

counterweight tanks

91 and 95 or draining it therefrom. Additional weight may be obtained by the use of a Weighted fluid instead of water.

In FIGURE 12C one form of a landing head 61 is shown as being provided with an outwardly flaring skirt 105 at its lower end to facilitate engagement with the upper end of the leading mandrel 62 when the former is lowered onto the latter. A suitable seal 106 is carried within the landing head 61 and is employed between the landing head 61 of the marine conductor pipe assembly and the landing mandrel 62 on the top of the blowout preventer 52. While a static seal could be employed in some cases, the sealing element 106 is preferably arranged within the landing head 61 so that it can be expanded inwardly against the landing mandrel 62 to form a fluidtight seal thereagainst. Alternatively, the landing head 61 may be provided with locking dogs (not shown) and take the form of the wellhead connector 47. The inner surface of the skirt 105 of the landing head 61 preferably forms a landing shoulder for resting in weightsupporting engagement on the top of the seating surface It is to be understood that only a slight amount of weight is supported by the wellhead assembly. In so doing, the marine conductor string will remain seated on mandrel when the hydraulic connecting means fail. As described hereinabove, the major por- 'tion of the weight of the marine conductor pipe assembly is supported by the buoyancy tanks with the

rest valves

56 and 57 in a suitable manner by any connector means well known to the art, as by safety joints 56a and 57a. Preferably, the connectors are of the type that may be disengaged remotely. The choke and kill

lines

54 and 55 are mounted in spaced relationship to the marine conductor pipe 60 so that they are positioned outside the

buoyancy tanks

76 and 77, as shown in FIGURES 12A and 12B, rather than having them pass through the tanks if the

lines

54 and 55 were arranged closer to the conductor pipe 60. In the event that the choke and kill lines pass through the

buoyancy tanks

76 and 77, it would be necessary to put sleeves longitudinally thorugh the tanks which were of a larger internal diameter than the outside diameter of the choke and kill

lines

54 and 55 so that the choke and kill lines would be permitted to move vertically relative to the conductor pipe 60 and the

buoyancy tanks

76 and 77 as the conductor v pipe was subjected to bending stresses during drilling operations.

The connections at the top of the choke and kill

lines

54 and 55 are shown in FIGURE 8 and FIGURE 12A. In order to contain well pressures the choke and kill lines are preferably made of rigid material of a strength sufiicient to Withstand any well pressures encountered during drilling operations. Although the choke and kill

lines

54 and 55 are provided with shut-

01f valves

56 and 57 at the wellhead which may be remotely closed by an operator on the drilling vessel 11, these valves may be subject to failure or their conrtol lines may become ruptured. Thus, for emergency purposes the choke and kill lines 54 and are provided with shut-off

valves

108 and 109 near the top thereof and at least above the water surface so that these valves may be closed manu ally, if necessary. To enable an operator to close these valves 108 and 109 a small platform 110 having a hand rail 111 is secured to the bottom of an attachment collar 112. As shown in FIGURE 9 the attachment collar comprises a split pipe section being hinged at 113 and being provided with suitable connector means, such for example as

flanges

114 and 115 which are secured together by bolts 116, so as to fixedly secure the collar 112 to the upper end of the conductor pipe 60. The collar 112 is also provided with a horizontally-disposed pivot pin 117 which pivotally secures a pair of

yoke arms

118 and 119 to the collar 112. The choke and kill lines are preferably supported by means of gimbal-mounted slips or any other suitable means of vertical support in the outer ends of the

yoke arms

118 and 119. Thus, the choke line 54 (FIGURE 9) is vertically supported and held down in a block 120 which is pivotally secured by a pivot pin 121 to a surrounding frame 122 which is in turn pivotally secured to the outer ends of the

yoke arms

118 and 119 by means of pivot pin 123 which is arranged with its axis in a direction normal to the axis of the pivot pin 121, both pivot pins 121 and 123 lying in a horizontal plane. It will be seen that as the drilling vessel 11 (FIGURE 1) moves off the vertical line 'of the well to cause the marine conductor pipe assembly to bend, the choke and kill

lines

54 and 55 bend and the support yoke arms 118 and 119 (FIGURE 9) will adjust themselves to eliminate introduction of any additional stresses into the kill and choke

lines

54 and 55 due to this condition.

In order to compensate for the rise and fall motion of the vessel, with wave action, relative to the upper end of the choke and kill

lines

54 and 55, the choke and kill

lines

54 and 55 are provided above their shut-off

valves

108 and 109 with flexible pipe line sections of any suitable type. As shown in FIGURES 8 and 12A the choke line is provided with

flexible couplings

124, 125, 126 and 127 which interconnect

pipe line sections

128, 129, 130 and 131. In turn, the kill line 55 is provided with

flexible couplings

133, 134 and 135 which

interconnect pipe lines

136, 137 and 138. The upper ends of

pipe lines

131 and 138 are provided with shut off

valves

139 and 140 which are part of a more or less conventional manifold. It is to be understood that the apparatus of the present invention may be modified in many ways while still forming an operative combination. Thus, for example the choke line 54 may be eliminated, it being sufficient in some cases that a single line extend from the drilling vessel 11 to the wellhead below at least some of the blowout preventers whereby a heavy fluid can he injected into the well in order to kill the well or to control the pressure therein in abnormally high pressure oil fields.

It will be seen that the apparatus of the present invention provides a simple marine conductor pipe assembly adapted to be readily installed or to be disconnected and withdrawn when the vessel is to move to another loca tion. The apparatus also provides means for suitably supporting one or more rigid small-diameter pipes adjacent a large-diameter marine conductor pipe with the combination of pipes being buoyantly supported to a large extent by buoyancy chambers. It is to be understood however that the entire marine conductor pipe assembly is to have a negative buoyancy under operating conditions so that there is no danger at any time of the entire assembly breaking loose from the wellhead at the ocean floor and fioatingto the surface in a manner so as to endanger or damage the floating vessel 11. This is especially important since the stability and buoyancy of the drilling vessel 11 may depend upon a relatively thinskinned or buoyancy chambers which could be readily punctured by a buoyant marine conductor pipe assembly shooting to the surface. At the same time the apparatus of the present invention provides unique counterweights which are readily adjustable as to support capacity for maintaining constant tension on the upper portion of the marine conductor pipe assembly.

We claim as our invention:

1. Apparatus for drilling, completing and working over an underwater well, said apparatus comprising operational platform means positioned above the surface of a body of Water,

a well base positioned below the surface of the water and including substantially vertical well base pipe means having a lower portion thereof fixedly anchored to the formation below said body of water and a portion extending upwardly above said formation,

marine conductor means connectible at its lower end to the upper end of said well base pipe means with the upper end of said conductor pipe extending above the surface of the water in the vicinity of said operational platform means,

buoyancy tank means secured to said marine conductor means below the surface of the water and having sufficient buoyancy to support a major portion of the weight of said marine conductor means, and

weight support means operatively secured to said marine conductor means near the upper end thereof and to said platform means for supporting that portion of the weight of said marine conductor means unsupported by said buoyancy tank means,

a vertically-extending tubular member of said well base in communication with said well base pipe means,

a wellhead connector carried at the lower end of said marine conductor means connectible to said tubular member,

small-diameter rigid conduit means extending from said operational platform means to said Well base,

conduit connector means securing the lower end of said conduit means to said well base in communication with the bore of said well base pipe means,

and valve means in said conduit means near the upper end thereof and above the surface of said body of water.

2. The apparatus of claim 1 including connector means securing said conduit means to said marine conductor means at spaced intervals therealong.

3. The apparatus of claim 2 wherein said connector means are fixedly secured to said marine conductor means and slidably secured to said conduit means to permit differential vertical movement of said conduit means relative to said conductor means when they are moved laterally.

4. The apparatus of claim 2 wherein said connector means are fixedly secured to said conduit means and slidably secured to said conductor means.

5. The apparatus of claim 1 including flexible pipe means in said small-diameter conduit means above the valve means therein above the surface of the body of water.

6. The apparatus of claim 2 wherein the uppermost connector means comprises movable yoke means, horizontal means securing said yoke means to the marine conductor means near the upper end thereof, and gimbal means securing said movable yoke means to said conduit means.

7. Apparatus for drilling, completing and working over an underwater well, said apparatus comprising (a) operational platform means positioned above the surface of a body of water on a vessel,

(b) a well base positioned below the surface of the water and including substantially vertical well base pipe means having a lower portion thereof fixedly anchored to the formation below said body of water and a portion extending upwardly above said formation,

(0) marine conductor means connectible at its lower end to the upper end of said well 'base pipe means with the upper end of said conductor pipe extending above the surface of the water in the vicinity of said operational platform means,

(d) buoyancy tank means secured to said marine conductor means below the surface of the water and having suflicient buoyancy to support a major portion of the weight of said marine conductor means,

(e) weight support means operatively ecured to said marine conductor means near the upper end thereof and to said platform means for supporting that portion of the weight of said marine conductor means unsupported by said buoyancy tank means,

(f) said weight means carried by said vessel and arranged for substantially free vertical movement, sheave means secured to said vessel at a fixed level above the uppermost position of said weight means, cable means having one end thereof secured to said marine conductor means, said cable means passing operatively over said sheave means with the other end of the cable means secured to said weight means, said weight means being free to move up and down as the vessel rises and falls due to wave action,

(g) movement-limiting means positioned in contact with said movable weight means for confining the mogement of said weight means along a selected r (b) said movement-limiting means comprising substantially vertically-extending rigid elongated members of a length at least equal to the maximum vertical movement of said weight means and arranged in contact with said weight means to prevent any substantial lateral movement thereof, and

(i) said weight means comprising variable weight tank means adapted to contain weighting material.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 7/ 1961 Great Britain. 8/1961 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

Claims

7. APPARATUS FOR DRILLING, COMPLETING AND WORKING OVER AN UNDERWATER WELL, SAID APPARATUS COMPRISING (A) OPERATIONAL PLATFORM MEANS POSITIONED ABOVE THE SURFACE OF A BODY OF WATER ON A VESSEL, (B) A WELL BASE POSITIONED BELOW THE SURFACE OF THE WATER AND INCLUDING SUBSTANTIALLY VERTICAL WELL BASE PIPE MEANS HAVING A LOWER PORTION THEREOF FIXEDLY ANCHORED TO THE FORMATION BELOW SAID BODY OF WATER AND A PORTION EXTENDING UPWARDLY ABOVE SAID FORMATION, (C) MARINE CONDUCTOR MEANS CONNECTIBLE AT ITS LOWER END TO THE UPPER END OF SAID WELL BASE PIPE MEANS WITH THE UPPER END OF SAID CONDUCTOR PIPE EXTENDING ABOVE THE SURFACE OF THE WATER IN THE VICINITY OF SAID OPERATIONAL PLATFORM MEANS, (D) BUOYANCY TANK MEANS SECURED TO SAID MARINE CONDUCTOR MEANS BELOW THE SURFACE OF THE WATER AND HAVING SUFFICIENT BUOYANCY TO SUPPORT A MAJOR PORTION OF THE WEIGHT OF SAID MARINE CONDUCTOR MEANS, (E) WEIGHT SUPPORT MEANS OPERATIVELY SECURED TO SAID MARINE CONDUCTOR MEANS NEAR THE UPPER END THEREOF AND TO SAID PLATFORM MEANS FOR SUPPORTING THAT PORTION OF THE WEIGHT OF SAID MARINE CONDUCTOR MEANS UNSUPPORTED BY SAID BUOYANCY TANK MEANS, (F) SAID WEIGHT MEANS CARRIED BY SAID VESSEL AND ARRANGED FOR SUBSTANTIALLY FREE VERTICAL MOVEMENT, SHEAVE MEANS SECURED TO SAID VESSEL AT A FIXED LEVEL ABOVE THE UPPERMOST POSITION OF SAID WEIGHT MEANS, CABLE MEANS HAVING ONE END THEREOF SECURED TO SAID MARINE CONDUCTOR MEANS, SAID CABLE MEANS PASSING OPERATIVELY OVER SAID SHEAVE MEANS WITH THE OTHER END OF THE CABLE MEANS SECURED TO SAID WEIGHT MEANS, SAID WEIGHT MEANS BEING FREE TO MOVE UP AND DOWN AS THE VESSEL RISES AND FALLS DUE TO WAVE ACTION (G) MOVEMENT-LIMITING MEANS POSITIONED IN CONTACT WITH SAID MOVABLE WEIGHT MEANS FOR CONFINING THE MOVEMENT OF SAID WEIGHT MEANS ALONG A SELECTED PATH, (H) SAID MOVEMENT-LIMITING MEANS COMPRISING SUBSTANTIALLY VERTICALLY-EXTENDING RIGID ELONGATED MEMBERS OF A LENGTH AT LEAST EQUAL TO THE MAXIMUM VERTICAL MOVEMENT OF SAID WEIGHT MEANS AND ARRANGED IN CONTACT WITH SAID WEIGHT MEANS TO PREVENT ANY SUBSTANTIAL LATERAL MOVEMENT THEREOF, AND (I) SAID WEIGHT MEANS COMPRISING VARIABLE WEIGHT TANK MEANS ADAPTED TO CONTAIN WEIGHTING MATERIAL.