US3008549A - Method and apparatus for tilting a mast - Google Patents

Description

Nov. 14, 1961 w. K. THORSON 4 METHOD AND APPARATUS FOR TILTING A MAST Filed March 19, 1956 2 Sheets-Sheet 1 ll llllllnum. l Hum."

30 b t AH -L. 'm%z #6 Nov. 14, 1961 w. K. THORSON 3,008,549

METHOD AND APPARATUS FOR TILTING A MAST Fi led March 19, 1956 2 Sheets-Sheet 2 ff V\ A. Tho/"Jan IN V EN TOR.

ATTOR/V' VJ United States Patent 3,008,549 METHOD AND APPARATUS FOR TILTING A MAST Warren K. Thorson, Dallas, Tex., assignor, by mesne assignments, to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware 7 Filed Mar. 19, 1956, Ser. No. 572,456

6 Claims. (Cl. 189-45) This invention relates to improvements in the handling of equipment laterally of a well location during the drilling of and performance of other operations on a'well, particularly at an offshore or other water location. one of its aspects, it relates to a mast for suspending equipment above a well in connection with the drilling thereof and performance of other operations thereon, and a method of using same which obviates the need for barge-mounted cranes conventionally employed at offshore locations for handling well equipment and the like laterally of the well.

In the drilling of offshore wells, it is common practice to convey a mast to the well location upon a floatable barge-mounted support. At the desired location the barge is submerged or the support otherwise fixedly located with respect to the subsurface level to provide a firm foundation for the mast. Themast is then properly positioned over arr-open space inwardly of a side of the support and above the well location, which space is known as a drilling slot." When so positioned, the mast may be used for suspending equipment above the well locationrto drill same and to perform other operations thereon, such as the completion of the well. In connection with such operations, it is necessary to set various items ofequipment, such as wellhead protective jackets and production platforms, at the welllocations.

For this purpose, it has been the practice to use, floatable barge-mounted cranes adjacent the mast support to lift the equipment from a position laterally of the well location for placement'over the well. However, the use of such cranes is normally quite expensive. For example, they may cost as much. as $8,000 to $10,000 a day, and the well may be so located as to require up to two weeks in travel time from the home port. Also, the floating barges are at the mercy of weather conditions and cannot operate in rough weather.

It is, therefore, an object of this invention to use a mast of the type generally employed in the drilling of and performing of other operations on a well as a crane boom for handling equipment laterally of the well location and, in the case of offshore wells, laterally of the fixed support for the mast.

A more particular object is to provide a novel method of converting a mast of this type from an upright position for suspending equipment above the well location to a tilted position for handling equipment laterally of the well location, in which tilted position there will be substantially no eccentric loading on the boom due to combined bending and compression forces.

Another object is to provide a mast construction in which the conventional hoisting means for the mast may 3,008,549 Pat'ented Nov. 1 4, 1961 "ice location; and, more particularly, further improvements which enable the use of such a mast as a crane boom with a mini-mum of structural modifications;

Yet another object is to provide in a mast of type described in the foregoing object, such improvements which enable the means for raising the mast to be further used in swinging it between upright and tilted positions. Other objects, advantages and features of this invention will be apparent to one skilled in the art upon a consideration of the written specification, the attached claims and the annexed drawings.

In the drawings, wherein like reference characters are used throughout to designate like parts:

'FIG. 1 is a side elevation of a mast embodying the features of the present invention which is mounted upon a platform at an olfshore location, and shown in a substantially horizontal position such as it may assume during conveyance to and from the offshore location;

FIG. 2 is a side elevation similar to FIG. 1, but in which the mast has been raised to an upright position in whch it may be used in drilling and per-forming other operations above the well; I

FIG. 3 is an end view of the mast in the upright position of FIG. 2, taken from the right thereof, and preparatory to being tilted;

FIG. 4 is another side elevation of the mast of FIGS. 1 to 3, but in which the mast has been tilted to a position for use as a crane boom in handling'equipment laterally of the well location;

FIG. 5 is a sectional plan view of the mast in the tilted position of FIG. 4, and taken substantially along broken line 55 of FIG. 4;

of the plat-form; and

FIG. 7 is a detailed side view of the lower end of the movable leg of FIG. 6, and in a position released from securement with the platform deck.

In accordance with the present invention, and with particular reference to the illustrative embodiment of the drawings, there is provided a mast 10 of substantially A frame construction so as to provide an open face (FIG. 3) and mounted upon a platform 11 for swinging movement about its lower end in a vertical plane transversely to said open face, between a lowered, substantially horizontal position as shown in FIG. 1, an upright position as shown in FIGS. 2 and 3, and a tilted position, as shown in FIGS. 4 and 5. As can be seen from the drawings, the platform 11 is disposed over a slot 28 (FIG. 5) toward one edge of a floatable barge-mounted support 13, and a headrest 12 is carried upon another part of the support 13 inboard of slot '28 for supporting a part of the mast in its lowered position.

The lower end of the mast 10 is pivotally connected to brackets 14 on the deck of the platform 11 and is be used in the handling of equipment laterally of the well I laterally supported in its upright position by a pair of spaced apart stiff legs 15. As can be seen from the drawings, the stiff legs 15 are pivotally connected at their upper ends to the mast 'at brackets 17 intermediate the upper and lower ends of the mast and releasably secured at their lower endsto brackets 16 on the deck of the platform so as to provide a rigid connection therebetween.

In a manner to .be described hereinafter, and in accordance with certain of the novel features of this invention, the stiff legs are also useable in raising and lowering as well as tilting the mast.

The illustrated mast, in so far as its raising mechanism is concerned, is of a type generally known in the field as a cantilever mast, wherein the stiff legs 15 form,

- along with auxiliary legs 15a, atriangular support which is fixedly'mountable on the deck of the platform in the position of FIGS. 1 and 2 of the drawings, wherein it is cooperable with a block and tackle means 18 suspended from the upper end of the mast for raising or lowering same. More particularly, a sling line 19 is extended be tween the pivotal joinder of the upper ends of legs and 15a forming the-triangular supports and a hook on the traveling block 21 of the block and tackle means 18. Also, a fast line 22 is guided over a sheave supported upon a shaft 20a (FIG. 3) which connects the upper ends of the triangular supports so as to extend between conventional drawworks 23 on the platform and a crown block 24 at the upper end of the mast. With the sling line 19 and fast line 22 secured as described, the d-rawworks 23 may be operated to take up on. the fast line 22 so as to swing the mast from the position of FIG. 1 into the position of FIG., 2, wherein it may be secured by means of brackets 17 to the upper ends of the triangular support, as previously mentioned.

The block and tackle means 18 may conventionally include, in addition to the drawworks 23, fast line 22, crown block 24, and traveling block 21, a deadline 26 which extends downwardly from a sheave on the crown block to a point fixed with respect to the platform, such as at 27. As well known in the art, the drawworks 23 includes suitable power means for rotating a drum about which the fast line 22 may be wound for selectively raising or lowering the traveling block 21. In this manner, with the sling line 19 removed, the block and tackle means may be used in conventional fashion in its upright position for drilling and performing other operations above the well location.

It should be understood that many of the novel features of the present invention are not necessarily limited to the particular mast construction above-described and shown in the drawings. Although, for reasons which will be apparent from the description to follow, this particular type of mast is preferred, the method of this invention may be carried out with other masts having an open face construction by means of which the block and tackle means may be swungfrom within the mast in its upright position to a position laterally thereof in its tilted position, as shown in FIG. 4.

The support structure 13 is fixedly located with respect to a subsurface level at an offshore location by means of supporting columns or piles 29 which are driven securely into the subsurface beneath the water level 30. Alternatively, the support may be any one of the other well known mobile type structures employing, in the place of the piles 29, a submergible hull or such a hull in combination with suitable piling. .At any rate, the details of the supporting structure do not form part of the present invention, but merely illustrate an environment for which the invention is particularly well suited. In fact, it is contemplated that the mast of the present invention and'the novel method for using same may be employed with considerable utility on land wherein the platform 11 would not be mounted at an offshore location.

As previously mentioned, the stiff raising legs are'also useable, in cooperation with the hoisting apparatus, for swinging the mast between upright and tilted positions. Thus, the lower ends of the legs 15 are releasable from their securement with brackets 16 and moveable across the platform under the control of the drawworks 23 in a manner to swing the mast as desired. More particularly, the lower ends of the raising legs are moveable away from brackets 16 in swinging the mast from its upright to a tilted position in an opposite direction from its lowered position.

As shown in FIG. 4, in the tiltedposition of the mast, the block and tackle means 18 is so located as to permit it to suspend equipment laterally of the well location as well as the support structure 13. Thus the block and tackle means may, in the tilted position of the mast, be

used either prior to or after the well is drilled for setting wellhead protective jackets and production platforms at the well location. Thus, with such equipment suspended from the traveling block when the mast is in the position of FIG. 4, another line (not shown) may be used to swing the equipment laterally into the position desired. Obviously, in the drilling of the well and performance of other operations thereabove, the hoisting apparatus may be used in the upright position of the mast in a manner well known in the art. For purposes of simplicity, and further since such operations are well known and do not perform a part of the present invention, certain of the equipment used in drilling the well has not been shown in the drawings.

" In its tilted position, the mast It) is laterally supported by one or more flexible guy lines 31 extended between the upper end of'the mast and points '32 fixedly mounted upon the support structure 13, as shown in FIGS. l, '2 and 3. In the preferred form shown, a pair of such guy lines are used, one on each side of the mast so, as to extend downwardly and outwardly from their connections with the mast at the upper portion thereof such as from their connections with opposite sides of crown block 24 as shown in FIG. 3. Such an arrangement provides a degree of stability against swinging of the mast out of its vertical plane of movement. Obviously, the guy lines 31 are of sufficient strength as to laterally support the mast in its tilted position and are of such length so that when extended by the tilted mast, they will support same in the desired predetermined position.

As previously mentioned, in the upright position of the mast, the stiff leg 15 provides a rigid connection between the platform and a point intermediate the upper and lower ends of the mast. According to the present invention, the rigid connection between the mast and platform is releasable such that the Weight of the tilted mast and any load supported therefrom is transferred to the lateral support provided byguy lines 31. In this manner, in the tilted position of the mast, the stiff legs 15 are rendered ineffective as force-transmitting members so that the mast is not loaded eccentricallydue to combined bending and compression stresses. That is, it will be understood that unless the rigid connection provided by the stiff legs 15 were rendered ineffective, the mast in its tilted position would act as a cantilever beam from the bracket 17 to its upper end and thus be subjected to bending stresses when loads-were supported-therefrom.

With particular reference now to the manner in which the stiff legs 15 serve to swing the mast between upright and tilted positions, it can be seen from FIGS. 1 1504 that the lower ends of the stiff legs can be provided with rollers 33, skids or the like, adapted to slide over'the deck of the platform 11 upon release from thebracket 16, in a manner to be described more fully hereinafter. The lower ends of the legs are also provided with-parts 34 (see FIG. 7) to which a sling line 35 maybe attached for extension about sheaves 36 on the deck of theplatform and upwardly for attachment to the hook ofthe traveling block 21. This connection between the block and tackle means and the lower ends of stiff legs 15 permits the movement of such legs-to be controlled in swinging-the mast between upright and tilted positions. Thus, with the fast-line from the drawworks guided about sheave 38, as shown in FIG. 4, and VVlth' guy lines 31 of the desired length extended between the upper ends ofthe mast and fixed points 32, the drawworks may be operated so as to ease off on the block and tackle means and thus permit the lower ends of the stiff legs to gradually move outwardly overthe deck of the platform inswinging the mast to a tilted position. 4

As the mast is gradually moved to approximately its predetermined tilted position, the tension in the line 35 is released so that the weight of the mast is transferred to the guy lines 31 and the stiff legs 15 are rendered inoperative as force-transmitting members. -It'will'be-un= derstood then that with the lateral support for the mast in its tilted position" being connected thereto at its upper end, and with the load suspended from the mast by means of the traveling block as shown in broken lines inFIG. 4, the mast will be loaded substantially in compression as a column only. Thus, it will be further understood that improved loading characteristics maybe obtained, in accordance with this invention, merely upon shifting of this lateral support from a point adjacent brackets 17 to a point upwardly toward the upper end of the mast. However, optimum results are obtained by connecting the lateral support provided by the guy lines 31 to the upper end of the mast so that substantially all combined bending and -compression stresses are removed.

The reason for sheaves 36 would appear obvious in that they enable the forces exerted by the lines 35 for controlling movement of the lower ends of the legs 15 to be directed along paths substantially coincident with the desired movement thereof. On the other hand, the sheave 38 permits the line 22 connected between the crown block 24 and drawworks 23 to be directed down the side of the mast opposite from'that from which the traveling block swings upon tilting of the mast. This, of course, enables a more desirable distribution of forces for raising and lowering the traveling block 21 in the tilted position of the mast. It should be understood, however, that the same purpose might be accomplished by skidding the drawworks 23 over the deck of the platform 11 from the position shown in FIG. 4 to a position on the opposite side of the'brackets 14. Also, drawworks mounted as shown in' FIG. 4 may be found to interfere with suspendingejquipment laterally of the well location, and thus provideanother reason for skidding same.

Where themast is sufficiently open, sheave 38 need not be used during tilting of the mast.

Suitablewinches' may be provided as shown at points 32 so that when the mast has been tilted in a manner as described above, its position may be adjusted by means of the guy lines 31. Of course, in such a case, the operation of the winches for the guy lines may be syncronized with one another in any suitable manner.

Still further, this means for tilting the mast may be used not only for the purpose mentioned, but also in making the .mast plumb when the platform upon which it is supported is not level with the earths surface. This may be especially helpful in the case of offshore drilling wherein the supporting structure may not have settled into the subsurface evenly or 'where'the subsurface itself is not level. 1 7

Apart from its usefulness in raising and lowering the mast, the stiff leg 15 provides a member of.minimum length for tilting the. mast, and thus reduces its overall cost of construction; Furthermore, in transferring the lateral support of the mast from a stiff or rigid'member, such as'the legs 15, to a flexible one such as the guy lines 31, this method provides the tilted mast with a desired flexibility forfunctioning as a crane boom.

To summarize this novel method of converting a mast of the general type described from use in an upright position for drilling and performing other operations above a well location to use in a tilted position for handling equipment laterally of the well location,'one or more 'guy lines 31 of a length to limit swinging of the mast to a predetermined tilted position are loosely'extended between the upper end of the mast and the fixed points 32. The sling line 35 is then extended from the hook on traveling block 21, about sheave 36, and to the attaching parts 34 on the lower ends of stiff legs 15. Upon release of the securement (to be described) of the lower ends of the legs 15 from brackets 16 on the deck of the platform 11, the'line 35 is gradually eased off so astopermitrollers 33 or skids to move over the deck of the platform. With the upper end of the legs 15 pivotally connected at brackets 17 to points intermediate the upper and lower ends of the mast, this movement of the legs causes the mast'to swing about its pivotal connection'withthe platform at brackets 14 and toward the predetermined tilted position. At a time when the mast has approximately reached its predetermined tilted position, the tension on the line 35 is released such that the mast extends the guy lines '31 and its weight is absorbedthereby. Thus, the rigid connection provided by'legs 15 is released and the mast is positively connected to the platform 11 only at its lower pivotal connection, so that any load suspended from the traveling block laterally of the well location will be transmitted through the pivotal connection to load the tilted mast as a column only.

Obviously, the mast is returned from its tilted to its upright position by a reversal of the foregoing. That is, the-line 35 is extended between the lower ends of stiff legs 15 and traveling block 21 so that whenthe drawworks is operated in a manner to gradually take up on the line 35, the rollers 33 are caused to move inwardly toward' the pivotal connection of the mast until such time as they are disposed opposite brackets 16 to permit the connection between the lower ends of the stiff legs and the brackets to be remade. Thus, themast will, in its upright position, again be laterally supported'by the stiff legs 15 which provide a rigid connection between an intermediate portion of the mast and the platform; Referring to FIGS. 6 and 7, the brackets 16 are provided with openings therethrough and 'aresecured in spaced apart relation to receive therebetween a plate 39 at the lower end of each stifi leg. Each plate has hollow journals 40 extending from each side thereof so that a pin 41 having a head 42 at one end and a rotatable latch 43 at its opposite end may be extended through the openings in the brackets 16 and the journals 40to secure the lower ends of the legs 15 in the position shown in the drawings. Furthermore, the rollers 33 are rotatably mounted upon the plates 39 beneath journals 40 for rolling engagement with the deck of the platform. Parts 34 may merely comprise pins projecting outwardly from a rearward portion of the plates 39 so as to'receive a suitable connection 44'on the end of sling line 35.

It is contemplated that the movement of the lower .ends of stiff legs 15 can be controlled or caused by means other than those specifically illustrated in the drawings, Thus, a hydraulic ram or jack, a screw or other means may be used to supply the'necessary force for moving the stiff legs.

Fromthe foregoing it will be seen thatthis invention is one Well adapted to attain all-.of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the method and apparatus.

It will be understood that certain features and su combinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not-in a limiting sense.

The invention having been described, what is claimed 1. In a method of converting a mast from use in an upright position in drilling and performing other operations on a well to use in a tilted position in handling equipment to one side of the: well location, wherein the mast is of a type mounted on'a platform for swinging movement in a vertical plane and laterally supported in its upright position by a leg providing a rigid connection between the platform and a point on the mast intermediate its upper and lower ends, the steps of mow ing one-end of said leg along the platform to swing the mast from its upright position to approximately a predetermined tiltedposition and during such movement of the leg employing it to provide lateral support for the mast, releasing the connection provided by said leg between the platform and mast, and laterally supporting the mast in its predetermined tilted position by a guy line connected between the upper end of the mast and a point fixed with respect to the platform, whereby loads upon the mast in said tilted position are prevented from being transmitted through said leg.

2. In a method of converting a mast from use in an upright position in drilling and performing other operations on a well to use in a tilted position in handling equipment to one side of the well location, wherein the mast is of a type mounted on a platform for swinging movement in a vertical plane and laterally supported in its upright position by a leg providing a rigid connection etween the platform and a point on the mast intermediate its upper and lower ends, the steps of connecting a guy line between the upper end of the mast and a point fixed with respect to the platform for limiting swinging of the mast from its upright position to a predetermined tilted position, controllably moving one end of said leg along the platform in such a manner as to swing the mast into approximately its predetermined tilted position while employing the leg to provide lateral support for the mast during its movement to said tilted position, and releasing the rigid connection between the mast and platform to permit the mast to extend the guy line and prevent loads upon the mast in said tilted position from being transmitted through said leg.

3. Apparatus for use in drilling and performing other operations on a well and handling equipment to oneside thereof, comprising a platform, a mast having an open face and mounted on the platform for swinging movement in one direction in a vertical plane from an upright to a tilted position, block and tackle means carried from the upper end of the mast for suspending equipment above the well location in the upright position of the mast and to one side of the well location in the tilted position thereof, a stiff leg pivotally connected at its upper end to a point intermediate the upper and lower ends of the mast, means for connecting the lower end of the leg to the platform to provide a lateral support for the mast in its upright position, said last mentioned connecting means being releasable, said mast when in said upright position being biased toward tilted position against the supporting action of said leg, means connectible between the lower end of the leg and said block and tackle means whereby upon release of the connecting means at the lower end of the leg such lower end can be controllably moved away from. the mast and along. the platform by manipulation of the block and tackle means to move the mast to tilted position while being supported by the leg, and a guy line connected between the upper end of the mast and a point fixed with respect to the platform to provide lateral support for the mastwhile in tilted position.

4; Apparatus of the character defined in claim 3, including rollers on said lower end of the leg engageable with the platform upon movement thereacross.

5. Apparatus for use in drilling and performing other operations on, an offshore well from a barge-mounted support and for handling equipment at one side of the support, comprising a platform above a drilling slot in the support, a mast having means for suspending equipment therefrom, means mounting the mast on the-platform for swinging movement in a vertical plane,,means for swinging the mast in one direction from a substantially horizontal to an upright drilling position, means including a stiff leg connected between the mast and platform when the mast is in its upright position and supporting the mast in its upright position in which equipment is suspended above the well location for drilling and performing said other operations on. the well through said drilling slot, said mast when in such upright position being biased toward tiltingin said one direction against the action of said stifi leg, said platform including support means extending in said one direction. from the stiff legs connection with the platform for supportably engaging the lower end of the stiff leg when said lower end is moved in said one direction, means for controllably moving the lower end of the stiff leg in said one direction along and in engagement with said support means so as to swing the stiif leg about its upper end to tilt the mast in said one direction from its upright to a tilted position while employing the leg to provide lateral support for the mast during its movement to its tilted position and upon the mast reaching its tilted position, being releasable from providing said lateral support to the mast, and other supporting means connected between the mast adjacent the upper 'end thereof and a point fixed with respect to the platform to support the mast in its tilted position.

6. Apparatus for use indrilling and performing other operations on an oflishore well from a barge-mounted support and handling equipment at one side of the support, comprising a platformabove a drilling slot in the support, a mast having means for suspending equipment therefrom, means mounting the mast on the platform for swinging movement in one direction in a vertical plane between a substantially horizontal position and an upright position for suspendingequipment above the well location, means for moving the mast between said substantially horizontal and upright positions, means including a stifi leg connected between the platform and the mast intermediate the masts ends for supporting the mast in said'upright position for drilling and performingsaid other operations on the well through said drilling slot, said mast when in its upright position having its center of gravity disposed to bias'it toward swinging in said one direction against the action of said supporting means, said platform including support means extending in said one direction from the stiff legs connection with the platform for supportably engaging the lower end of the stifif leg when said lower end is moved in said one direction, means for controllably moving the lower end of the stiff leg along and in engagement with the support means and away from the mast while the leg is providing lateral support for the mast to swing the mast in said one direction from its upright position to a tilted position for disposing the suspending means to one side of the well location, and cable means connected between the mast adjacent its upper end and a point fixed with respect to the platform for supporting the mast in its tilted position.

References Cited in the file of this patent UNITED STATES PATENTS 2,168,837 York Augr8, 2,332,479 Woolslayer et al. Oct. 19, 1943 2,345,253 Funk Mar. 28, 1944 2,399,656 Armstrong May 7,1946 2,410,959 Brown: Nov. 12, 1946 2,447,439 Thompson Aug. 17, 1948 2,475,933 Woolslayer et al July 12, 1949 2,539,693 Moon Jan. 30, 1951 2,611,580 Troche et a1 Sept. 23, 1952 2,617,500 Cardwell et al Nov. 11', 1952 2,660,382 Wilson Nov. 24, 1953 2,742,260 Patterson Apr. 17, 1956 2,792,198 Braun May 14, 1957 2,840,197 Jenkins etal June 24, 1958 FOREIGN PATENTS 707,372 Germany .a June 20, 1941 1,112,143 France Nov. 9,1955 Great Britain Dec. 19, 1956

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