US3161027A - Pipe support for use in marine drilling - Google Patents

Description

Dec. 15, 1964 s. GRAHAM PIPE SUPPORT FOR USE IN MARINE DRILLING 2 Sheets-Sheet. 1

Filed May 31, 1963 70/77 J. Gra /7am INVENTOR. awe;

ATTORNEY Dec. 15, 1964 T. s. GRAHAM PIPE SUPPORT FOR USE IN MARINE DRILLING Filed May 31, 1965 2 Sheets-Sheet 2 ATTORNEY 3,l6l,27 Patented Dec. 15, 1964 United States Patent Ofiiice 1 3 161 027 1 rare surronr ron iisanv Man-inn nnrrrnso Toni S. Graham, New Grieans, Lat, assignor toficean Drilling & Exploration (Iompany, a corporation of Delaware Filed May 31, 1953, Ser. No. 284,644 7v Claims. (Cl. 6146) This invention relates to apparatus for supporting pipes and wellhead equipment employed in drilling and equipping oil and gas Wells which are drilled through water bodies, and more particularly to apparatus for supporting pipes and wellhead equipment employed in drilling and equipping wells drilled from floating vessels.

Present marine drilling practices employ two general types of drilling or working platforms. *One type comprises a platform structure which is supported directly from the submerged land and the other comprises a heating vessel or platform from which drilling and equipping operations are conducted under afloat-conditions. The latter type is coming i'nto'increasing'use as drilling is conducted in ever greater water depths, which presently extend to several hundred feet.

In afloat-condition drilling, movement of the floating platform necessarily occurs, and a current practice, particularly at deep Water locations, is to use underwater blowout control and other wellhead equipment, which is mounted on the protection pipe generally at a point near the submerged land surface, and movement of the floating platform is tolerated by the flexing of the slender drill string between the rotary and blowout preventor entrance.

" This drill string carries no vertical load but merely the torque required for turning the bit, This requires remote fluid pressure control conduits, constant tension guide lines for guiding equipment into place, underwater observation 'and signaling devices, and other complicated and expensive mechanisms for assuring proper installation and maintenance of safe control of the well at all times. Such underwater control equipment has heretofore been employed because of the difliculty of effectively support ing and operating through wellhead equipment on top of a relatively slender protection pipe string which is subject to excessive lateral movement resulting from wind and wave effectson the floatingvessel to which it is con nected. The protection or conductor pipe string conventionally is the pipe string which is first driven into the land to extend above theIwater surface and through which drilling of the well is conducted It functions as a column supporting the quite heavy loads of the blowout prevention and other above-water equipment which is mounted directly thereon.

As is known from standard engineering principles, the vertical load that can be safely carried by a column is a function of its slenderness ratio (ratio of length to radius of. gyration). This safe vertical load is reduced if the,

load is applied eccentrically. or .if an external force pro duces bending in the column; In marine drilling, the protective casing string or drill pipe would necessarily be relatively small in diameter and of relatively great length, and would be subjected to cross-bending from ocean currents and Waves, with the result that its vertical loadcarrying capacity would be reduced to practically Zero.

It is a primary object. of the present invention to provide an auxiliary supporting structure for the conventional protection pipe strings which will permit the mounting inthe conventional manner of necessary blowout preventor and otherv wellhead equipment on the protection pipe, irrespective of its slenderness ratio and allow a limited horizontal movement of the protection pipe string as the floating platform moves about due to wave, wind and current action.

In accordance with this invention, the supporting structure comprises an elongate tubular caisson which is adapted to be jetted or driven into the submerged land and which has a length when in place suflicient to extend above the water surface. The caisson is of suitable dimensions to resist the stresses occasioned by water currents and waves, and carries a frame adjacent its upper end and above the water surface designed to form an enclosure for the protection pipe and which, in cooperation with a guide yoke carried by the protection pipe, will provide strong and safe support for the latter and any loads carried thereon and allow movement of the same.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful .of the upper end of the pipe support and the supported pipe string;

FIG. 3 is an pipe support; 7 FIG. 4 is a crossssectional view along line 4-4 of FIG-.3; and

PIG, 5 is a plan View of the support frame and the supported pipe string. 7

Referring first to FIGS. 3 to 5, inclusive, the pipe support includes an elongate, hollow caisson 10 having an upward conical taper which may extend substantially uniformly from bottom to top of the caisson, or may ex tend throughout the upper portion of the caisson beginning at about the submerged land surface or so-called mud line. The caisson is fitted with internal piping, indicated at 11, extending to the surface and communieating with jets, indicated at 12, of conventional design, adjacent the lower end of the caisson for conducting streams of air and water tothe lower end of the caisson to sink the caisson to a desired depth in the underlying land. The use of such jetting arrangements is wellknown in the art and the specific details thereof do. not form a part of the invention, it being merely sufficient that any suitable jetting arrangement be employed which is capable of sinking the lower end of the caisson to the desired depth into. the submerged land, either by jetting alone, or in combination with pile driving or other suitable forcing means. I g

A horizontally disposed support frame, designated generally by the numeral 15, is secured about the caisson near its upper end and at an elevation which will be above the normal water surface at the particular location, and

elevational view, partly in section, of the normally above the wave crests to be encountered in.

cured to frame members 16 through'the cross-members 1'7, whilelower mounting ring 19 is secured to the frame members by diagonal braces 20. The support frame will be secured to caisson 10 by welding or in any other suitable and generally conventional manner. 3y reason of e) the taper of the caisson, the internal diameter of upper mounting ring 18 will be slightly smaller than that of lower mounting ring 19 and the two mounting rings may be considered to define a frusto-conical sleeve which is slidably fitted over the upper end of the caisson and secured thereto, as indicated, in any suitable manner.

The upper faces of the frame members form bearing supports for a yoke, designated generally by the numeral 21, which is adapted to be rigidly secured to the conductor pipe 22, which will be driven into the underlying land through one of the bays 15a of the support frame. Yoke 21 is of any suitable structural shape adapted to provide sufficient load-bearing strength for the purpose for which it is used. As illustrated, it may be in the form of a T section having a length sufficient to span one of the bays and to rest upon frame members 15 and 17 defining the opposite sides of the bay. Yoke 21 is provided centrally with a hollow boss or sleeve 23, having a bore such as to allow the yoke to be slipped over the end of conductor pipe 22 when the latter has been put in place in the land bottom. Yoke 21 will then be welded or otherwise rigidly secured to the conductor pipe, so that it forms a load-bearing member of the conductor pipe which is slidable on the upper surfaces of the frame members.

Referring now to FIG. 1, operation of the device is conducted as follows: Caisson 10 will be driven or jetted into the land bottom by operations conducted from a fioating drilling platform D, and frame 15 will be mounted on the upper end of the caisson above the water line,

indicated at W. A string of protection or conductor pipe 22 will be driven through one of the bays a of frame 15, generally parallel to caisson 10, to whatever depth it may be desired to set this conductor pipe. When the latter has attained the desired depth, it may be cemented in place in accordance with conventional practice, and yoke 21 is secured thereto in position to be slidably supported on the upper surfaces of the frame members. Blowout preventors B of the usual form, and any other conventional wellhead equipment may be mounted on the conductor pipe and operatively connected to the drilling rig or platform D. With the conductor pipe so equipped and in place, the usual drilling and other operations necessary to drill and complete a well will be conducted through the conductor pipe. All loads, such as the wellhead equipment and any other loads imposed on the conductor pipe, will be transmitted by yoke 21 to frame 15 and caisson 10, which will serve to elfectively support the vertical loads on the conductor pipe'string and allow horizontal movements.

With the particular geometrical configuration of frame 15, as illustrated, it will be seen that four different conductor pipe strings may be supported by caisson for wells drilled using this single support structure. By using a supporting frame of other geometrical configuration, it will be obvious that any larger or smaller number of wells may be drilled with the supported assistance of a single caisson. By way of example, assuming drilling in a water depth of 200 feet, caisson 10 may have an overall length of 312 feet, of which the lower 80 feet may be driven into the land bottom and the upper 32 feet will extend above the normal level of the water body in which the structure is located. A caisson of this length will have a diameter of about 12 feet at the lower end tapering to a diameter of 6 feet at the upper end. In this example, the lower 80 feet may be made cylindrical, with the taper extending through the upper 232 feet. Frame 15, of the square shape illustrated, will be 23 feet, 6 inches on a side, thereby providing four bays a, each approximately 11 feet, 9 inches square. With yoke 21 long enough to extend entirely across one of the bays 15a, the area of each bay permits a considerable degree of deflection of the upper end of the conductor pipe, limited by the distance between the frame members. In a frame of the dimensions noted, the upper end of the conductor pipe, depending upon its diameter, can move through a circle having a radius of approximately 5 feet. The length of yoke 21 will be greater than the greatest dimension of bays 15a so that it will maintain its bearing on opposite sides of a bay throughout the maximum deflection of the conductor pipe within the confines of the bay. In most cases, the conductor pipe will range in size from about 24 inches to 36 inches, these being conventional dimensions for conductor pipes ordinarily used at marine locations. Sliding friction between the yoke and frame surface may be reduced by the use of suitable lubricants.

The upward taper of the caisson is most desirable in order to reduce the wave forces which may be exerted against the caisson section which extends through and above the water surface, it being recognized that the maximum wave forces occur at the wave crest and decrease downwardly through the water.

Generally stated, the dimensions of the caisson will be selected to provide a stable column having the requisite load-supporting characteristics under the particular conditions of use. In relation to the conductor pipe, the caisson dimensions will be selected to provide a slenderness ratio in the range from about one-third to about one-sixth that of the conductor pipe.

By the provision of a supporting structure in accordance with this invention, many advantages are provided in connection with well drilling at marine locations. Thus, the blowout preventors and wellhead equipment may be located above the water surface for ready observation, maintenance, and use generally. Moreover, the supporting structure permits a substantial amount of flexing or bending. of the conductor pipe within, however, pre-determined or controlled limits, so that excessive and dangerous bending will not occur. This, in turn, permits employment of a protector pipe of minimum size, since it need not be depended upon for support of any heavy loads. The entire supporting structure can be installed from the drilling platform and thus does not require the use of any divers, submarine gear or underwater observat1on mechanisms. Moreover, as a well is completed, it can be put on production immediately and the caisson may be used, if desired, as a storage vessel. In case the floating platform has to pull away from the Well, or is forced off because of adverse sea conditions, the well has safe support. If a well, or wells, are dry, the structure can be readily surfaced and moved to another location. In some instances it may be desirable to run a protectron pipe through the interior of the caisson. In such cases, the external support frame may be dispensed with and yoke 21 supported for horizontal sliding movement directly on the upper end face of the caisson.

It will be understood that various changes and modifications may be made in the details of the illustrative embodiment within the scope of the appended claims, but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A pipe support for use in marine drilling, comprising, an elongate tubular caisson vertically mountable in the land bottom underlying a water body and having a length when in place to extend above the surface of the water body, a horizontally disposed laterally extending support frame mounted on the caisson at a point adapted to be located above the water body, said frame having an opening therethrough to receive the upper end of a pipe to be driven into said land bottom alongside said caisson, and a horizontally disposed load-transmitting member slidably supported on an upwardly facing surface of said frame surrounding said opening and adapted to be rigidly secured to a pipe, said caisson having a slenderness ratio in the range from about one-third to about one-sixth of that of a pipe to be supported thereby.

2. A pipe support according to claim 1, wherein said caisson is formed to have an upward conical taper.

3. A pipe support according to claim 3, wherein an upper portion of said caisson extending through the surface of the Water body is upwardly'conically tapered.

4. A pipe support for use in marine drilling, comprising, an elongate tubular caisson vertically mountable in the land bottom underlying a water body and having a length when in place to extend above the surface of the water body, and a load-transmitting member slidably supported for horizontal movement on the caisson at a point thereon adapted to be located above the surface of the Water body and adapted to be rigidly secured to a pipe to be supported by the caisson.

5. A pipe support for use in marine drilling, comprising, an elongate tubular caisson vertically mountable in the land bottom underlying a water body and having a length when in place to extend above the surface of the water body, a horizontally disposed laterally extending support frame concentrically mounted on the caisson at a point adapted to be located above the water body, said frame having a plurality of openings therethrough each adapted to receive the upper end of a pipe to be driven into said land bottom alongside said caisson, and a horizontally disposed load-transmitting member slidably supported on an upwardly facing surface of said frame surrounding an opening and adapted to be rigidly secured to a pipe, said caisson having a slenderness ratio in the range from about one-third to about one-sixth that of a pipe to be supported thereby.

6. A pipe support member according to claim 5 wherein said support frame comprises an open structural frame defined by peripheral elements and a plurality of cross members, a pair of centrally positioned vertically spaced mounting rings attachable to said caisson, the upper one of said mounting rings being secured to said cross members, and diagonal braces securing said peripheral elements to said lower ring.

7. A pipe support for use in marine drilling, comprising, an elongate tubular caisson vertically mountable in the land bottom underlying a water body and having a length when in place to extend above the surface of the water body, a horizontally disposed laterally extending support frame mounted on the caisson at a point adapted to be located above the water body, said frame having an opening therethrough to receive the upper end of a pipe driven into said land bottom alongside said caisson, and a horizontally disposed load-transmitting member slidably supported on an upwardly facing surface of said frame surrounding said opening and adapted to be rigidly secured to a pipe, said caisson having a slenderness ratio in the range from about one-third to about one-sixth that of a pipe, to be supported thereby, and means mounted on the caisson for jetting the same into said land bottom.

Claims (1)

1. A PIPE SUPPORT FOR USE IN MARINE DRILLING, COMPRISING, AN ELONGATE TUBULAR CAISSON VERTICALLY MOUNTABLE IN THE LAND BOTTOM UNDERLYING A WATER BODY AND HAVING A LENGTH WHEN IN PLACE TO EXTEND ABOVE THE SURFACE OF THE WATER BODY, A HORIZONTALLY DISPOSED LATERALLY EXTENDING SUPPORT FRAME MOUNTED ON THE CAISSON AT A POINT ADAPTED TO BE LOCATED ABOVE THE WATER BODY, SAID FRAME HAVING AN OPENING THERETHROUGH TO RECEIVE THE UPPER END OF A PIPE TO BE DRIVEN INTO SAID LAND BOTTOM ALONGSIDE SAID CAISSON, AND A HORIZONTALLY DISPOSED LOAD-TRANSMITTING MEMBER SLIDABLY SUPPORTED ON AN UPWARDLY FACING SURFACE OF SAID FRAME SURROUNDING SAID OPENING AND ADAPTED TO BE RIGIDLY SECURED TO A PIPE, SAID CAISSON HAVING A SLENDERNESS RATIO IN THE RANGE FROM ABOUT ONE-THIRD TO ABOUT ONE-SIXTH OF THAT OF A PIPE TO BE SUPPORTED THEREBY.

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