US2505088A - Well-drilling rig - Google Patents

Description

April 25, 1950 c, ATHY WELL DRILLING RIG Filed June 14, 1946 Patented Apr. 25, 1950 OFFICE WELL-DBIIJ lNG BIG Clifl'ord R. Atliy, Columbus, Ohio, assignor to Intel-national Derrick & Equipment 00., Columbus, Ohio, a corporation of Ohio Application June 14, 1946, Serial No. 670,638

Claims. (01. 254-145) 1 This invention relates to well-drilling rigs, and has particular reference to an improved ll'nereeling and guiding mechanism for use in connection with such rigs.

The present trend toward deeper wells, in the production of petroleum oils, throws a severe burden on the standard wire cables used in raising and lowering well casing, drill pipe and other appliances. It is quite well recognized in the industry that the weak linkin modern rotary rigs adapted for deep drilling is to be found in the wire cable, this factor being primary deterrent to drilling to depths of the order of 15,000 feet or lower.

In practice, a drilling line having a diameter of 1% inch is deemed to be the largest one for practical usage. Some consideration has been given to cable lines having a diameter of 1 inch, but sucha line is so stiff and heavy that its use would require sheaves 'of extra large diameters (60 to 70 inches) with spooling drums of correspondingly increased diameter. High grade 1% inch cable has a breaking strength of 65 tons, and the maximum allowable line pull thereon, based on a standard safety factor of 5 to 1, is 26,000 pounds.

The maximum loads in 15,000 feet drilling, usually encountered in lifting 6% inch casing off bottom, are between 200 and 250 tons, averaging 225 tons. If the maximum line pull is limited to approximately 26,000 pounds, the handling of this load would require sixteen to eighteen lines, that is, lengths of the working cable between the sheaves of a traveling block and those of q the crown block of a drillingrig and which sustain the loads to be lifted. Such a'large number of lines operates to reduce the hoisting speed to about one-half of that normally employed. Ordinarily, ten lines are the maximum number of lines consistent with satisfactory hoisting speeds. i

Therefore, the industry at the present time is faced with the alternatives of either using cable line of extra large diameter, and withits accompanying special and larger type sheaves and spooling drums, in order to sustain the loads in deep well drilling and provide normal hoisting speeds, or to use cable lines of standard diameter, and with standard sheave and drum sizes, and increase thev number of lines between block sheaves, with greatly decreased hoisting speeds.

Therefore, it is an object of the present invention to provide a well-drilling rig adapted for the drilling of deep wells of the character in- 2 employ a cable line of standard diameter with the requisite number of lines between block sheaves to enable the cable to withstand safeLv the working loads imposed thereon, but wherein provision is made to provide standard hoisting speeds.

In the ordinary drilling rig, the working line or cable is fastened at one end to a spooling drum, and from this drum the cable is trainedsuccessively around sheaves provided in a crown block at the top of the derrick and sheaves provided on the traveling block or pulley arranged over the well bore, the opposite end of the line or cable being fastened (dead-ended) to the mast of the rig or its associated base structure. This method of training the working line imposes limitations on the speed by which the same may be operated to raise and lower the traveling block since but one end thereof is being wound or unwound on a single drum. Therefore, the present invention consists in providing the rig with a pair of synchronously driven spooling drums, the

working line having one of its ends spooled around one of said drums and its other end around the second of the drums, so that when the drums are simultaneously rotated, both ends of the working line will be reeled about said drums or unreeled therefrom, whereby through the use of the dual drums the raising and lowering speeds of the traveling block may be increased over ordinary practice when the same number of lines are used between the crown and traveling blocks, or maintained at a normal speed when the number of lines of the working cable between the sheaves of said blocks is increased to compensate for greater loads.

For a further understanding of the invention, and additional objects and advantages thereof. reference is to be had to the following description and the accompanying drawing, wherein:

Fig. 1 is a diagrammatic view in side elevation of a well-drilling rig formed in accordance with the present invention;

Fig. 2 is a front elevational view disclosing the upper portion of the rig with its associated crown and traveling blocks, and disclosing the reeving of the cable around the sheaves of said blocks;

Fig. 3 is a top plan view of the dual cable spooling drums, and illustrating diagrammatically the passing of the cable around the sheaves of the crown and traveling blocks.

Referring more particularly to the drawings, the numeral I designates the mast or derrick of a rotary drilling rig. Mounted on the top of the mast is a crown block 2 which carries a plurality (1168M. and wherein h ri is constructed to of cable sheaves 3 which are'mounted for rotation on an axle I. The floor structure I of the derrick supports a pair of cable drums, indicated at 6 and I. These drums are mounted for rota tion in a suitable supporting frame 8,.which is formed with journal bearings for the reception of the supporting and drive shafts 8 of said drums. In this instance, the shafts have fixed thereon sprockets it), over which pass an endless chain H, the chain drive thus provided having a l to 1 ratio between the drums in order that their rotation may be synchronized. One of the shafts 9 is provided with a clutch 12 of any suitable type which is engageable with a driven sprocket l3, loosely mounted on the shaft carrying the clutch. A drive chain I 4 passes over the sprocket l3 and leads to another sprocket II, which is driven by any suitable prime mover l8 through speed reducing gearing, not shown.

While, in the interest of simplicity, it may be desirable to drive both drums by a common power transmission, nevertheless, it will be understood that separate or independent drives for the drums may be used. Also, the drums may be equipped with the usual band-type brakes II, which may be actuated pneumatically, hydraulically or mechanically to insure equalization of pressures on all brake drums. Each drum may also be equipped with the conventional hydraulic retarder, indicated at l8.

A working cable has been shown at I! in the drawings. This cable at one of its ends is secured to and wrapped around the drum I, and from this drum the cable extends upwardly outside the derrick, passing over an offset sheave 20 which, advantageously, may be mounted for rotation in the frame of the crown block 2 in a lateral position with respect to the main group of sheaves 3. From the sheave 20, the cable is trained successively around the sheaves 3 of the crown block and around the sheaves 2| of a depending traveling block 22, which is arranged as usual over the well bore.

In deep well drilling, the crown and traveling blocks 2 and 22, respectively, are provided with an extra large number of Sheaves, the number depending upon the loads to be handled. In this respect, it is practicable to use as high as 16 to 18 lines between the sheaves of the traveling and crown blocks. After the working line has been reeved through the sheaves of said blocks, it is trained downwardly within the derrick and secured to and wrapped around the drum 8, this being in contrast with the usual method'of deadending this end of the line by fastening the same to a stationary anchor. Since both ends of the line arejoined to a rotating drum, instead of one end, the winding or unwinding of the working line or cable may be accomplished with approximately twice the speed of that obtainable with the use of but a single drum. This makes possible the employment of a large number of lines between the block sheaves and the maintenance of satisfactory hoisting speeds.

In a conventional single drum rig, torsional loads or stresses at the crown block are quite severe. The live and dead lines of the cable come off at diagonally opposite corners of the crown block and therefore exert pulls in opposite directions. In other words, the torque is equal to the horizontal component of the dead or live line pull multiplied by the width of the block. Because fewer lines must be used in the single drum rig, the line pull is greater and naturally the horizontal component of the pull is also greater.

4 ing is reduced or minimized by the working position of the offset sheave 20, so that the length of the line leading from the drum 1 to the crown block is disposed outside the mast or derrick and in registration with one end of the crown block. This arrangement of the sheave 20 eliminates for all intents and purposes torsional stresses, leaving only horizontal-shear.

The spooling of both ends of the working line, as herein set forth, does not in any way interfere with the use of modern weight or stress indicators. Formerly it was the practice to associate a stress indicator with the stationary dead ended line. More recently, however, the industry is employing such weight or strain indicators in the traveling block assembly and, therefore, with such indicators the spooling of both ends of the working line becomes entirely practicable and does not interfere in any way with accepted practice.

I claim:

1. In a drilling ring, a derrick, a crown block mounted on the top of said derrick, said block embodying a frame carrying a plurality of rotatable cable sheaves arranged in axial alignment, a guide sheave disposed laterally of the derrick at one side of said aligned sheaves, a traveling block having a plurality of cable sheaves, a pair of cable-spooling drums, means for rotating and controlling the rotation of said drums, and a cable, said cable being secured at one of its ends to one of said drums and at its other end to the other of said drums, intermediate portions of said cable being trained over said guide sheave and the sheaves of said crown and traveling blocks.

2. In a drilling rig, a derrick, a crown block mounted on the top of said derrick, said block embodying a frame carrying a plurality of rotatable cable sheaves arranged in axial alignment, a guide sheave disposed on the top of said derrick and arranged laterally of the axially aligned sheaves of the crown block, a traveling block having a plurality of cable sheaves, a pair of cable-spooling drums, a cable line connected at one end with one of said drums, said cable line being trained upwardly from said last-named drum on the outside 01 said derrick and passed over said guide sheave, from said guide sheave the intermediate portions of said cable being trained downwardly and upwardly in successive order around the sheaves of said traveling and crown blocks, and from said crown block downwardly inside the derrick with the other end of said cable line connected with the second of said drums, and means for rotating and controlling the rotation of said drums.

3. The method of operating the cable line of a drilling rig wherein the rig embodies a derrick, a multiple sheave crown block, a multiple sheave traveling block and a. pair of power driven linespooling drums, the steps which comprise securing one end of said line to a first drum, passing the line from said first an upward direction and outside of said derrick over a guide sheave disposed laterally of the crown block, then passing the line downwardly from the guide sheave and inside the derrick around a first sheave of the traveling block, training the line upwardly over a first sheave of the crown block, thence downwardly and upwardly in successive order around the remaining sheaves of the crown and traveling blocks, and following passage of the line around the last sheave of the In the present invention, this torsional ioad- 10 cr wn block t ainin the same downw rdly within the confines of the derrick and securing the same to the second of said drums.

4. The method of operating the cable line of a drilling rig wherein the rig embodies a derrick, a multiplesheave'crown block, a multiple sheave traveling block and a pair of power driven linespcoling drums, the steps which comprise secur ing one end of said line to a first drum, passing the line from said first drum in an upward direction and outside of said derrick over a guide sheave disposed laterally of the crown block, then passing the line downwardly from the guide sheave and inside the derrick around a first sheave of the traveling block, training the line upwardly over a first sheave oi the cm block, thence downwardly and upwardly in successive order around the remaining sheaves oi the crown and traveling blocks, following passage of the line around the last sheave of the crown block training the same downwardly within the confines of the derrick and securing the same to the second of said drums, and synchronously rotating said drums.

5. A drilling rig, a derrick mast, a crown block on the top of the derrick t, a traveling block,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,414,295 Suman et a1. May 2, 1922 1,727,724 Mundy Sept. 10, 1929 2,359,919 Johnson Oct. 10, 1944 2,389,226

Woolslayer et a1. Nov. 20, 1945

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