US2120224A - Derrick structure - Google Patents

Description

June 7, 1938. w. scHwl-:MLEIN 2,120,224

DERRI CK STRUCTURE Original Filed April 16, -1936 rae-,mee June 7, 193s Urr PATENT oFFicE sgnor to The Parkersburg Rig pany, Parkersburg, W. Va., a corporation of 'West Virginia Continuation of application Serial No. 74,777,

April 16, 1936.

This application January 18, 1938, Serial No. 185,618

6 Claims. (Cl. 18th-16)4 o This invention relates to derrick structures and `is a continuation of my copending application Serial No. 74,777, filed April 16, 1936.

Oil well derricks are commonly constructed along conventional lines which are well known, such derricks comprising four legs suitably braced with respect to each other with each of the legs formed straight from end to end. Such a derrick is commonly provided adjacent its upper end with a crown platform surmounted by the usual gin pole, and at the proper height above the derrick oor the derrick supports a working platform.

It is the usual practice, for example in deep well rotary drilling, to rack several stands of drill pipe in a vertical position within the derricln` Each stand of pipe usually is 90 feet long, being made up of three foot sections, and the stands of pipe 'rest upon a pad on the derrick floor and lean against what is known as a "fourble board' at the elevation of the derrick platform.

' The successive stands of pipe are added to the pipe sections extending into the well, and it is necessary for the drilling crew to shut down actual drilling whenever it is necessary to rack additional stands of pipe. Accordingly it is desirable to stack as many stands of pipe as possible to avoid the delay and expense incident to frequent shut-downs.

Derricks have been conveniently made 122 feet in height, but with the increase in deep well drilling it has been found that there is not sumcient space at the working platform to accommodate the desirable number of stands of pipe. Accordingly derricks employed in deep well drilling have been increased to a height of 136 feet and by such increase of 14 feet inthe height of the derrick a gain of only 1 foot in space is obtained at the working platform to accommodate the pipe stands. Obviously the increase in the cost of the higher derrick is substantially out of proportion to the relatively minor advantages obtained from its use. This problem has been under discussion by leading engineers in the industry and no satisfactory solution of the 'problem has been obtained.

An important object of the present invention is to provide a derrick structure of the character indicated wherein-substantially greater space at the working platform `is obtained without substantially increasing the cost of the derrick.

a further object is to provide a derrick structure wherein increased space for the pipe stands is obtained at the working platform without increasing the height of the derrick.

Athe usual manner.

.A further object is to provide a novel derrick structure wherein the conventional straightlegged derrick is departed from by providing a plurality of legs each of which is slightly angled at the height of the working platform to increase the available space for pipe stands without increasing the height of the derrick.

A further object is to provide a derrick struc-- ture which tapers in diierent degrees above and below an intermediate point at the height ofthe working platform, the degrees of taper above and below. such intermediate point being respectively greater and less than the taper of a conventional derrick.

Other objects and advantages ofthe invention will become apparent during the course of the following description.

In the drawing I have shown one embodiment of the invention. In this, showing- Figure 1 is a side elevation of the improved derrick structure,

Figure 2 is an enlarged fragmentary, side elevation of a portion of the derrick structure at the height of the working platform, the latter being omitted,

Figure 3 is a section on line 3-3 of Figure 2, and,

Figure 4 is a detail sectional view on line 4 4 of Figure 1, the working platform and all braces 1 up of lower sections I2 extending from the derrick oor I3 t'o the point at which the working platform il is supported. Each derrick leg further includes an upper section I5 extending from` the working platform to the crown platform I6 which is of the usual type supported at the top of the derrick. Any desired form of gin pole I1 is supported by the upper end of the derrick and projects upwardly above the crown platform in The legs of the derrick are braced with respect to each other at suitable points by girts I8 and braces I 9, most of these bracing elements being of the conventional type and connected to the derrick legs and to each each other as indicated in Figures 1 and 2, the-- broken lines I9' being in alinementwith/the/leg angled intermediate its ends on both faces as at 22 so that its upper and lower end portions t against the faces of the adjacent end portions of the leg sections I2 and` I5. The line of the angles 22 of the splice plate 2I and the abutting edges 20 of the leg sections lie in a common plane as will be apparent. Itl will be apparent that both sections I2 and I5 of each leg II lie in a single plane which is in a common plane with the diagonally opposite leg I I. The arrangement of one leg section I5 above its associated leg section I2 is indicated in Figure 4.

Inside splice bars 23 are arranged against the respective inner faces of the two abutting leg sections and each splice bar 23 is likewise angled in the plane of the abutting edges 20. The respective leg sections, the'splice plate2l and the splice bars 23 are secured by bolts 24 extending therethrough. Accordingly these elements are l' firmly anchored with respect to each other. The

lower end of each leg section I5 is slotted as at 26 to receive one of the bolts 24 at each side of v the derrick to facilitate assembly of the parts.

To add increased rigidity to the elements described, it will be noted that the adjacent pairs of legs II are braced with respect ot each other by girts 25, similar to thegirts I8 commonly employed in derrick structures. Each girt receives one of the bolts 24 and is further secured to its adjacent splice plateV 2| by at least one additional bolt 21. Certain of the diagonal braces I9, such as the braces 28 in Figure 2, have one end secured in position by certain of the bolts 24, and each of these braces is further secured in position by at least one additional bolt 29 passing through each brace and the adjacent splice plate 2|. The ends of the braces 28 opposite their connection with the splice plates 2| are secured to the derrick leg sections in the usual manner.

The working platform I4 has been omitted from Figure 2 for the purpose of illustration. This platform per se may be conventional in construction and is supported with respect to the derrick in any suitable manner, as for example, by means of the horizontal girts 25. It is from this platform that the pipe stands are handled in the usual manner, and one of these stands has been indicated in position in Figure land' designated by the numeral 3U. As is the common practice, this pipe stand is indicated as being made up of three pipe sections 3I, although it will be obvious that the present invention is not concerned in any manner with the particular form of pipe stands. Y

The derrick structure is adapted for the same uses as the conventional derrick structures and has substantial advantages thereover. It will lbe apparent from Figure 1 that if the upper leg sections I5 were arranged in alinement with the lower leg sections I2, as suggested by the broken lines I9', the derrick would extend to a substantially greater height before reaching the proper size at the upper end of the derrick. Such additional height would be useless except to provide the desired derrick size at the working platform and would involve a substantial increase in the cost of building and erecting the derrick. As previously stated, derricks of increased height have been restored to almost solely for the purpose of providing for an increased number of stands of drill pipe, it being considered necessary in the art to form the derrick legs straight from end to end. The highly desirable results 'of the present construction are obtained by tapering the derrick above the working platform to a degree greater than the taper in the conventional derrick and by tapering the derrick below the working platform to a degree less than the taper of a conventional derrick.

In this connection it would be assumed that the break in the continuity of each derrick leg would substantially weaken the structure of the derrick, but in practice this has been found not to be the case. The derrick structure described possesses at least the strength of conventional derrick structures. As a matter of fact, since the lower leg sections I2 are more nearly vertical than in conventional constructions, the stresses on all of the girts and diagonal'braces below the working platform are reduced.

While a derrick constructed in accordance with the present invention is slightly more expensive than a conventional derrick of the same height, it effects a substantial economy over the cost of a higher derrick of conventional construction having the same advantages with respect to the stacking of stands of pipe at the working platform. The provision for stacking an increased number of pipe stands obviously reduces the frequency with which the drilling operation ordinarily is stopped to permit the racking of additional stands of pipe. l

The use of the splice plates 2| and splice bars 23 provides adequate bracing means between the adjacent leg sections and the use of girts 25 approximately in the horizontal plane at which the angles occur in the several legs effectively prevents the spreading or buckling of the legs. rI'hus it will be apparent that the structure provides substantial advantages over prior constructions without sacrificing any of the necesintersect along the vertical axis of the derrick.,-

Accordingly it will be apparent that the vertical plane of each leg is coincident with the axis of the derrick, and accordingly vertical strains are taken up by the legs in the vertical planes of the neutral axes of the angle sections from which the legs are fabricated.

Since the drill pipe is usually racked on only one side of the derrick, it will be apparent that increased space need not be provided on all four sides. Accordingly the present invention contemplates making one or more sides of the derrick in accordance with the angular leg arrangement ,shown in Figure 2. In other words, the

present invention contemplates constructing at,

niemand 'rangement of parts may be resorted to without departing trom the spirit of the invention or the scope of the subjoined claims.

l claim:

l. A well drilling derrlclr comprising a plurality of legs and being relatively slightly tapered to decrease in size from its lower end to a` point intermediate its yheight and being tapered to a relatively greater degree to decrease in size upwardly from such intermediate point, the degrees ci taper above and below said intermediate point being respectively greater and less than the taper oi a conventional drilling derrick, and a working platform arranged adjacent such intermediate point.

2. A well drilling derricls comprising a plurality of legs and being relatively slightly tapered to decrease in size from its lower end to a point intermediate its height and being tapered to a relatively greater degree to decrease in size upwardly from such intermediate point, the de grees of taper above and below said intermediate point being respectively greater and less than the taper o a conventional drilling derriclr, each leg comprising upper and lower sections arranged at a slight angle with respect to each other at such inteediate point, a splice plate secured to the adjacent ends oi the sections of each leg, and a working platform arranged at such intermediate point.

3. A well drilling derricls comprising a plurality of legs and being relatively slightly tapered to decrease in size from its lower end to a point intermediate its height and being tapered to a relatively greater degree to decrease in size up-. wardly from such intermediate point, the degrees oi taper above and below said intermediate point being respectively greater and less than the taper ci a conventional drilling derricls, each leg comprising upper and lower sections arranged at a slight angle with respect to each other at such intermediate point and `having abutting ends, a splice plate secured to the adjacent ends of the sections of each leg, said splice plate being angled intermediate its ends to correspond to the angle between said leg sections whereby the end portions of said splice plate lie hat against the portions ci said leg sections to which said splice plate is secured, and a working platform secured to the derricls substantially at such intermediate point.

e. A well drilling derrich having a plurality oi pairs of diagonally opposite legs, each such pair of legs lying in a ce no; plane throughout their height and being slightly inclined toward each other from their lower extremitiesto a pointintermediate their height, and being inclined to a slightly greater extent toward each other upwardly from such intermediate point, the degrees of taper above and below said intermediate point being respectively greater and less than the taper of a conventional drilling derriclr, eachA leg comprising upper and lower sections having their adjacent ends terminating in the horizontal plane of such intermediate point and arranged in abutting relationship, a splice plate secured to the adjacent ends of the sections of each leg, and kbracing means for said legs iny cluding Aa girt connected horizontally between each adjacent pair of splice plates.

5. A well drilling derriclr comprising a plurality of legs each lying in a vertical plane coincident with the vertical axis of the derrick, each leg being slightly inclined inwardly toward such vertical axis from the lower end of the leg to a point intermediate the height of the derrick and being inclined at a relatively greater angle toward such vertical axis upwardly from such intermediatepoint, the degrees of taper above and below said intermediate point being respectively greater and less than the taper of a conventional drilling derrlck, each leg being formed of upper and lower straight sections having their adjacent ends abutting and. terminating at such intermediate point each section being formed angular in cross-section, a splice plate of an angular cross-sectionl corresponding to the angular` cross-section of said leg sections and secured to the adjacent ends of the sections of each leg, and a horizontal girt connecting each f adjacent pair oi splice plates.

6. A well drilling derrick comprising a plurality of legs and being relatively slightly tapered to decrease in size from its lower end to a point intermediate its height and being tapered to -a relatively greater degree to decrease in size upwardly from such intermediate point', the degrees of taper above and below said intermediate point being respectively greater and less than the taper of aconventional drilling derrick, each leg being formed of a pair of straight sections of corresponding angular cross-section having their adjacent ends arranged in abutting relationship in the horizontal plane of such intermediate mint, bracing means connected between said legs and arranged substantially in said horizontal plane, and a warming platform arranged adjacent said intermediate point and carried by said bracing me.

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