US3163239A

US3163239A - Marine conductor and pipe support for drilling underwater wells

Info

Publication number: US3163239A
Application number: US241692A
Authority: US
Inventors: Vries Douwe De; Ronald L Geer
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1962-12-03
Filing date: 1962-12-03
Publication date: 1964-12-29
Anticipated expiration: 1981-12-29
Also published as: GB1029808A

Description

Dec. 29, 1964 Filed Dec. 3, 1962 D. DE VRIES ETAL 3,163,239 MARINE CONDUCTOR AND PIPE SUPPORT FOR DRILLING UNDERWATER WELLS 3 Sheets-Sheet l D. 'DE VRIES FIG. I R. L. GEER BY%, Hm.

THEIR AGENT Dec. 29, 1964 E VRIEs ETAL 3,163,239

MARINE CONDUCTOR AND PIPE SUPPORT FOR DRILLING UNDERWATER WELLS Filed Dec. 3, 1962 3 Sheets-Sheet 2 INVENTORSI D. DE VRlES R. L. GEER THEIR AGENT Dec. 29, 1964 D. DE VRIES ETAL MARINE CONDUCTOR AND PIPE SUPPORT FOR DRILLING UNDERWATER WELLS 3 Sheets-Sheet 5 Filed D80. 5, 1962 FIG. 5

INVENTORS'.

D. DE VRIES R. L. GEER BY: Hi c THEIR AGENT United States Patent F 3,163,239 MARINE CGNDUCTOR AND FREE SUPPORT FQR DMLLTNG UNDERWATER WELLS Douwe de Vries and Ronald L. Gear, Metairie, La, assignors to Shell Oil iiompany, New York, N.Y., a corporation of Delaware Filed Dec. 3, 1962, Ser. No. 241,692 Claims. (Cl. 1757) This invention relates to the drilling of oil and gas Wells and pertains more particularly to apparatus for drilling wells at offshore locations where the drilling operations are carried out from a floating base positioned at the surface of the water and the well being drilled is provided with a Wellhead assembly positioned below the surface of the water.

Heretofore, most offshore wells have been drilled either from stationary platforms anchored to the ocean floor or from movable barges temporarily positioned on the ocean floor. Regardless of the manner in which the wells are drilled, most wells were completed in a manner such that the outermost tubular member of the well extends upwardly from the ocean floor to above the surface of the water where a wellhead or Christmas tree was mounted thereon for controlling the production of the well. Drilling offshore wells by either of these methods was carried out in much the same manner that wells are drilled on land. Thus, the string of drill pipe that was suspended from the derrick passed through the rotary table in the floor of the derrick and thence downwardly into the wellhead assembly which was positioned just below the operating floor of the derrick or the drill barge, well above the surface of the water. At most, there was only a few feet of drill pipe between the rotary table and the top of the conductor pipe or wellhead assembly on which blowout preventers were usually mounted.

A recent development in the art of drilling'wells offshore has been a method for drilling and completing wells from a floating drilling base which was employed to suspend a string of drill pipe therefrom, with the drill pipe extending down through the water to a Wellhead or conductor pipe positioned below the surface of the body of water. Generally, the wellhead assembly was positioned on the ocean floor and anchored thereto by cementing a conductor pipe into the ocean floor. With the floating drilling base anchored over the wellhead assembly positioned on the ocean floor, well drilling operations could be carried on in water depths of from 100 to 1500 feet or more. A method of drilling and completing an underwater well on the ocean floor in this manner is described in copending application, Serial No. 830,538, filed July 30, 1959, to Haeber et al.

Since it is practically impossible to anchor a floating drilling unit or barge to the ocean floor so that the barge maintains a fixed position at all times directly over a wellhead assembly positioned on the ocean floor, strings of tubular goods employed in drilling the well from the floating drilling unit are subjected to unusual bending conditions due to the movement of the drilling unit. Movement of a floating drilling unit at the surface of the ocean is caused by wind and wave forces and may take the form of a roll, pitch and/or surge from a posi tion directly over the well being drilled. If the bending forces to which a string of pipe is subjected are too severe, the pipe will be damaged. To prevent damage of a pipe string, for example a string of drill pipe, drilling operations have to be suspended whenever conditions of the sea are such that the drilling units movement exceeds the allowable working range or bending limits of the pipe string.

It is therefore an object of this invention to provide apparatus for increasing the working range of a floating 3,163,239 Patented Dec. 2%, 1964 well drilling unit subjected to wave and other forces tending to cause the unit to roll at the surface of a body of water or to move horizontally from a position directly over an underwater well. i

A further object of the present invention is to provide apparatus for properly distributing the bending forces induced in a string of drill pipe extending from a floating drilling barge into a wellhead positioned beneath the surface of a body of water when the barge moves from a position directly over the wellhead.

These and other objects of this invention will be understood from the following description taken with reference to the drawing, wherein: p 7

FIGURE 1 is a diagrammatic view illustrating a floating drilling unit or barge anchored to the ocean floor over :a drilling location with a string of drill pipe extending from the barge into a wellhead assembly positioned on the ocean floor;

FIGURE 2 is a plan view of the pipe support apparatus of the present invention when positioned in a support frame on a drilling vessel.

FIGURE 3 is a longitudinal cross-sectional view of the support trame of FIGURE 2 taken along the line 3-4:.

FIGURES 4 and 5 are longitudinal views, taken in cross section, of the present pipe support apparatus in its unloaded and loaded positions, respectively.

Referring to FIGURE 1 of the drawing, a drilling barge, vessel or platform 11, of any suitable floating or fioatable type is illustrated as floating at the surface of a body of ,Water 12 and substantially fixedly positioned over a preselected drilling location, as by being anchored to the ocean floor 13 ,by suitable anchors (not shown) at the ends of

anchor lines

14 and 15. Equipment of this type may be used when carrying out well drilling operations in water varying from about 100 feet to 1500 feet or more in depth. The drilling vessel is equipped with a suitable derrick 16 as well :as other auxiliary equipment needed during drilling, such for example as a rotary table 17, and a hoist system including fall lines 18, crown block 19, traveling block 20 and power swivelor elevator 21 adapted to be secured to the upper end of a string of drill pipe 22 extending through the rotary table 17. The dernick 16 on the drilling vessel 11 is positioned over a drilling slot or well 24 which forms a .vertical opening extending vertically through the barge in a conventional manner. When using the equipment of the present invention, the slot 24 of the vessel may be either centrally located or extend in from one edge. Additionally, Well drilling operations may be carried out over the side of a barge or vessel without using the slot, if desired. In the event that drilling operations are carried out over the side of a barge, the vertical opening through the barge through which the drill string 22 extends would berin the form of an opening through the platform serving as the base for the derrick 16. I

A wellhead assembly 25 is schematically shown as being positioned on the ocean floor 13 and being fixedly anchored thereto by a conductor pipe or well casing 26 which extends into the ocean floor 13 and is preferably cemented therein. An underwater wellhead assembly of this type is described in copending application, Serial No. 830,538, filed July 30, 1959, to Haeber et al., and may comprise a base plate 27 having a plurality of upwardlyextending guide columns fixedly secured thereto and conend of a marine conductor pipe 35 which may be in the form of a large diameter, say 16 inch, pipe made up in sections to extendfrom the wellhead assembly 25 to a point beneath the rotary table 17 of the drilling vessel 11. The upper end of the conductor pipe 35 is tubular member 3? which compensatesfor rise and fall of the vessel 11 around the marine conductor pipe 35. The lower portion 38 of the telescoping joint which forms the upper end of the marine conductor pipe 35 below the telescoping joint is held upright in any suitable manner, as by

cables

40 and 41 which are secured to suitable means for supplying a constant tension to turn is mounted centrally below the rotary table 17 and extends from a point underneath the rotary table 17 to its connection 34 at the top of the Wellhead assembly 25 on the ocean floor 13. While the horizontal pipe support means 58 (FIGURES 4 and is illustrated as being positioned just below the bell nipple'23 of the.

marine conductor pipe 35 and at a level with the auxiliary deck 42, it is to be understood that the horizontal the cables, as for example, constant tension hoist means (not shown).

The drilling vessel 11 may be provided with one or more

auxiliary decks

42 and 43 extending across the drilling slot 24 to facilitate the mounting of some of .pipe support member 58 mounted outside the marine a vertical line passes through the rotary table 17, the

marine conductor pipe 35 and the wellhead assembly on the ocean floor. As wind and wave forces movethe drilling barge 11 horizontally off the center line through the well, the drill pipe string 22 extending through the rotary table and marine conductor pipe first comes in contact with the rotary table 17. A lateral force is developed between the pipe string 22 and the rotary table 17 so that a bending of the pipe string 22 takes place opposite the rotary table, that is, where the two are in contact. At the same time the drill pipe 22 would be centrallylocated withinthe marine conductor pipe s 35, as illustrated in FIGURE 4 and the marine conductor pipe 35 would in turn be centrally located between the I cylindrical element 55 of theframe 50. As the amountlaterally-extending

plates

51, 52, 53, and 54 which rest' I V tween the rotary table 17 and the pipestring 22 and deon the

beams

44, 45, 45 and .47, respectively. As shown in FIGURE 3, the frame has an opening through the .center thereof in which is positioned facylindrical element which is fixedly secured by welding to the frame 59. The frame 59 is preferably of split construction with the two portions being vconnected together by bolts 65. l a a In FIGURE 4, the upper end of the marine conductor of horizontal movement 'of the drilling vessel 11 indistance above and below therotary table 17. Generally, the bendingis at a maximum at the point of contact be- Continued movement of the drilling vessel 11 in the same direction horizonftally' causes the pipe string 22 to come in contact with pipe 35, at the point where it passes through the auxiliary deck 42, is provided with suitable means, such for example as an outwardly-extending flange 56 which may be welded. to the marine conductor pipe 35. The flange 56 or any other suitable meansmay be employed for mounting the rim 57 of an annular resilient horizontal pipe support means 58 concentrically with the marine conductor pipe 35. Suitable connectors such as bolts 59 may be employed .to connect the rim 57-to the flange 56. The horizontal pipe support-means 58 in its simplest form may take the formof a large, say 5 footdiameter,

For ease in explanation and descriptive purposesthe term pipe string and drill pipe string will be employed, it being understood that the principles discussed hereinbelow apply to any tubular goods that may be used in well operations such as casing, tubing, drill pipe, etc.

The resilient inflatable horizontal pipe support tire Also, the principles to be discussed hereinbelow apply to a pipe string being run in or pulled out of a well through a marine conductor pipe, while rotating the pipe string or not rotating the pipe string as the case may be.

In the operation of equipment of FIGURE 1, the

drill pipe string'22 is suspended by the hoist system of the derrick 16 and passes down through the rotary table 17 and into the bell nipple 23 at the top of the marine 1 conductor pipe .35. The marine conductor pipe 35 in the inner Wall of the marine conductor pipe 35, as shown in FIGURE 5. At the same time the marine conductor pipe 35 applies .a force 'to the resilient horizontal pipe support member 58 which is compressed more or less (dependent on its degree of inflation) under its load against the vertical cylindrical member 55 of the sup port frame 50 which transmits the load to the drilling vessel 11. Thus, an adjustable magnitude of bending is induced in the section of drill pipe opposite the tire 58, relieving some of the bending in the section of pipe opposite the rotary table 17. With continued movement of the vessel 11 in the same direction, the force between the horizontal support tire 58 and the marine conductor pipe 35 causes bending inthe drill pipe string 22 at the point opposite the tire '58 to increase, while the force between the rotary table 17 and the drill pipe string 22 .and consequently the bending in the drill pipe string 22 at a point opposite the rotary table 17 remains fairly uniform.

If the bending in the pipe string 22 opposite the rotary table 17 was near the maximum stress limit of the pipe at the time the pipe string was opposite the lower point ofasupport opposite the tire 58 and thereafter remains nearly constant, then any additional horizontal movement of the vessel will merely induce an amount of bending in the section of pipe opposite the horizontal support tire 58 without endangering the pipe at the point opposite the rotary table 17. The apparatus of the present invention providesfor adjustable additional horir zontal support for a drill pipe in order to reduce the bending stresses in the pipe by distributing the bending forces over more length of the pipe. At the same time,

the apparatus of the present invention provides means for cushioning the movement of the marineconductor pipe 35 against a fixed structure of'the drilling vessel in a manner so as to permit the marine conductor pipe to assume a nonvertical position Within the slot of the drilling vessel without damage to the marine conductor pipe. The construction of the tire 58 may be selected so that it may be inflated from say zero to 125 psi. and thus be capable of exerting onto the pipe various reactional forces up to a maximum of 40,000 lbs. at 125 psi. before collapsing to the position shown in FIGURE 5. The maximum bending thus allowed in the pipe is dependent on the magnitude of the tensile stress in the pipe. Therefore, the air pressure in the tire 58 is pref erably increased with an increasing hook-load, i.e., the load of equipment hung from the hoist system of the derrick 16. The supporting tire 58 is preferably no greater than I 20 feet below the rotary table 17.

With conventional floating drilling units, the drill pipe 22 is supported vertically with either slips set in the rotary table or by elevators on the traveling block. In either case, as the drilling vessel 11 surges and/or rolls, a horizontal force develops between the drill pipe 22 and the rotary table 17. Bending results in the section of pipe opposite the rotary table 17. The magnitude of the bending stress allowed is a function of the magnitude of the movements of the drilling vessel 11 and the hook or slip load. If the vessels movements exceed certain limits, the magnitude of the bending will cause damage to the drill pipe 17 and/ or the marine conductor pipe 35. Thus, by providing a horizontal pipe support in addition to the rotary table 17, the magnitude of the bending stress in the section of pipe opposite the rotary table can be reduced by inducing a second lateral force onto the section of pipe opposite the other horizontal pipe support which is adjustable by degree of inflation of the tire 58. A power-swivel could be used and connected to the top of the drill string instead of using a rotary table. In such a case a slip bushing or other suitable bearing would be used where the rotary table is normally located.

We claim as our invention:

1. Apparatus for providing horizontal support to a non-vertical section of drill pipe extending from a floating drilling base at the surface of a body of water and through a wellhead assembly positioned belowthe surface of said body of water, said apparatus comprising a wellhead assembly positioned below a body of water and anchored to the floor of said body of water,

a floating drilling base at the surface of the body of water normally positioned over said wellhead assembly, said base having a vertical opening through at least a portion thereof,

a drill pipe string depending from said floating drilling base and extending downwardly through said vertical opening in said base and through said'water and said wellhead assembly,

a marine conductor pipe surrounding said drill pipe string and secured at the lower end to said wellhead assembly and extending upwardly to the drill.- ing base, the upper end of the conductor pipe being arranged for limited movement relative to said drilling base in the vertical opening thereof, and

resilient horizontal displacement pipe support means carried by said marine conductor pipe on the outer surface thereof and near the upper end thereof within the vertical opening of said floating drilling base and in engagement at all times during operations with at least a portion of the drilling base forming the vertical opening thereof.

2. The apparatus of claim 1 wherein. said resilient horizontal pipe support means includes means for varying the resiliency of said support means.

3.-The apparatus of claim 1 wherein said resilient horizontal pipe support means comprises an annular inflatable ring member coaxially mounted on said marine conductor pipe.

4. The apparatus of claim 1 including horizontal frame means removably secured to said floating drilling base over the vertical opening therein, said frame means hava ing a central hole therethrough, a cylindrical element fixedly secured to said frame means on the edge of the hole therethrough, the inner diameter of said cylindrical element being at least equal to that of the resilient horizontal pipe support means.

5. The apparatus of claim 4 wherein said frame means and said cylindrical element are formed of at least portions split along a vertical plane and means for connecting the two portions together.

References Cited by the Examiner 0 UNITED STATES PATENTS 2,155,919 4/39 Wooler 30 8l84 2,259,942 10/41 Stroud 308l84 XR 2,775,869 l/57 Pointer 6146.5 2,873,580 2/59 Suderow 6l46.5 3,015,360 1/62 Stratton 166--66.5 3,032,125 5/62 Hiser -7 CHARLES'E. OCONNELL, Primary Examiner. BENJAMIN HERSH, Examiner.

Claims

1. APPARATUS FOR PROVIDING HORIZONTAL SUPPORT TO A NON-VERTICAL SECTION OF DRILL PIPE EXTENDING FROM A FLOATING DRILLING BASE AT THE SURFACE OF A BODY OF WATER AND THROUGH A WELLHEAD ASSEMBLY POSITIONED BELOW THE SURFACE OF SAID BODY OF WATER, SAID APPARATUS COMPRISING A WELLHEAD ASSEMBLY POSITIONED BELOW A BODY OF WATER AND ANCHORED TO THE FLOOR OF SAID BODY OF WATER, A FLOATING DRILLING BASE AT THE SURFACE OF THE BODY OF WATER NORMALLY POSITIONED OVER SAID WELLHEAD ASSEMBLY, SAID BASE HAVING A VERTICAL OPENING THROUGH AT LEAST A PORTION THEREOF, A DRILL PIPE STRING DEPENDING FROM SAID FLOATING DRILLING BASE AND EXTENDING DOWNWARDLY THROUGH SAID VERTICAL OPENING IN SAID BASE AND THROUGH SAID WATER AND SAID WELLHEAD ASSEMBLY,