US3333820A - Oil well drilling apparatus with traveling block guide - Google Patents

Description

1967 H J. WOOLSLAYER ET AL 3,333,820

OIL WELL DRILLING APPARATUS WITH TRAVELING BL Filed May 17, 1966 OCK GUIDE 2 Sheets-Sheet l 0 A77 ORNE V51,

1, 1967 H. .1. WOOLSLAYER ET AL 3,333,820

OIL WELL DRILLING APPARATUS WITH TRAVELING BLOCK GUIDE Filed May 17, 1966 2 Sheets-Sheet 2 #0415? J WIN can JEN/(M45 United States Patent 3,333,820 OIL WELL DRILLING APPARATUS WITH TRAVELING BLOCK GUIDE Homer J. Wooislayer and Cecil Jenkins, Tulsa, Okla., and

Erwin A. Campbell, Wexford, Pa., assignors to Lee C.

Moore Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 17, 1966, Ser. No. 550,674 Claims. (Cl. 254-135) ABSTRACT OF THE DISCLOSURE At least three guide cables are suspended in an oil well derrick in widely spaced locations around the traveling block. There are means at the bottom of the derrick for normally holding the cables taut. The traveling block is connected with the cables, which diverge from it toward the top and bottom of the derrick for restraining lateral movement of the block.

In drilling oil wells, a traveling block is moved up and down inside a derrick. The term derrick will be used herein to mean masts as well as standard derricks. Occasionally the wind becomes so strong that it causes a traveling block to swing against the side of the derrick, which can damage the derrick. When drilling from a floating vessel, the problem can become much more serious. Due to wave action, the vessel pitches and rolls and this can cause the traveling block and the side of the derrick to crash into each other. The damage that can result can be appreciated better when it is realized that some traveling blocks weigh as much as 25,000 pounds.

To prevent a traveling block from swinging dangerously in a derrick, rails have been mounted rigidly in the derrick and the traveling block has been provided wtih rollers or slides for moving up and down the rails. This is quite efifective in many cases, but it has been found that under some conditions the tendency of a heavy block to swing will tear the rails loose from the derrick because there is no give in the connection. A way to get around this problem is to substitute taut cables for rails, but an objection to such cables is that in order for them to restrain lateral movement of the traveling block they must be drawn up so tightly that they put a considerable load on the derrick. Also, since the cables are straight and parallel, the amount of tension to which they are subjected in restraining lateral movement of a traveling block is all out of proportion to the load that tends to produce that movement. For example, in a derrick about 140 feet tall provided with a straight, taut guide cable at one side of the traveling block, the cable is subjected to a tension of about 350,000 pounds just in preventing the block from being displaced laterally more than one foot by a force against it of 10,000 pounds. This requires a very large cable and adds needless loading to the derrick.

It is among the objects of this invention to provide oil well drilling apparatus, in which the traveling block is guided in its vertical travel by taut cables of reasonable size that do not load the derrick dangerously when the block attempts to swing sideways.

In accordance with this invention a traveling block is suspended in a derrick for movement up and down inside of it. At least three guide cables are suspended in the derrick from its top part in widely spaced locations around "ice the traveling block. At the-bottom of the derrick there are means for holding the cables. Traveling means secured to the traveling block connect it with the guide cables and are movable up and down with the block. The guide cables are taut and diverge from the traveling block toward the top and bottom of the derrick in order to restrain lateral movement of the traveling block in the derrick. Preferably, the cable-holding means include means for loading only the guide cable or cables that are pulled sideways by lateral movement of the traveling block, the tension on the remaining cable or cables being relieved at that time.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a diagrammatic side view of a derrick with the traveling block hanging on the vertical center line of the derrick;

FIG. 2 is a view, similar to FIG. 1, but showing the traveling block forced sideways a short distance;

FIG. 3 is an enlarged horizontal cross section, taken on the line IIIIII of FIG. 1;

FIG. 4 is a diagrammatic side view of a modification;

FIG. 5 is a view, similar to FIG. 4, but showing the traveling block forced sideways a short distance; and

FIG. 6 is an enlarged perspective view of the cylinder and piping assembly.

Referring to FIGS. 1 and 2 of the drawings, an upwardly tapered four-legged derrick 1 is shown, on top of which the usual crown block 2 is mounted. Suspended on the center line of the derrick by lines 3 supported by the crown block is a traveling block 4. A continuation of the lines extends down to drawworks 5, by which the traveling block can be moved up and down in the derrick in the usual manner.

It is a feature of this invention that the traveling block is prevented from swinging against the side of the derrick because of wind pressure or because of the pitching and rolling of a floating vessel on which the derrick may be mounted when drilling in water. Accordingly, at least three, and preferably tour, guide cables 6 are suspended in the derrick from its top part. These cables are in widely spaced locations around the block. When four cables are used as shown here, each one is attached to the top part of the derrick, most suitably near a derrick leg. At the bottom of the derrick there are means for holding the cables near the lower ends of the four legs. The cables are held taut. Contrary to prior practice, they are not straight because they have to extend inwardly from the top and bottom of the derrick toward the traveling block, to which they are attached by means 7 secured to the block. Because the cables extend from the upper and lower corner portions of the derrick vertically and inwardly toward the traveling block, they converge toward the block. Regardless of how the block is connected with the guide cables, the connection is such that the block remains free to move up and down in the derrick while being guided by the cables.

It will be seen that as the traveling block is lowered and approaches the bottom of the derrick, the change in the angles of the guide cables will require the cables to stretch. In fact, they would have to stretch so much that they would break if they were clamped to the top and bottom of the derrick. To avoid that, the cables are made long enough for their inherent resiliency to permit the necessary stretching. One way of doing this is to double the-length of each cable by making it in the Patented Aug. 1, 1967 form of a continuous loop, the upper end of which is' supported by a sheave 8 in the top of the derrick while the lower portion of the loop extends around a sheave 9 in the bottom of the derrick. The means 7 by which the traveling block 2 is connected with the guide cables can move up and down them, or it can be clamped to the cables because they can travel around the sheaves as the block is raised and lowered.

Whereas in a 140-foot derrick, for example, a 10,000- pound side thrust on the traveling block puts a straight guide cable under a tension of about 350,000 pounds, a similar pull on a single angular guide cable arranged as disclosed herein will put that line under only about 35,000 pounds tension. This is a reasonable value for both the guide cable and the derrick. Furthermore, again due to this particular arrangement of cables diverging from the traveling block toward the top and bottom of the derrick, when one cable is stretched by lateral movement of the traveling block the tension on the opposite side is reduced or eliminated, as shown in FIG. 2, whereby the vertical load on the derrick exerted by the latter cable is reduced or eliminated likewise.

The four guide cables will take care of lateral movement of the block in all directions. This traveling block guide system has the advantages that there is some elasticity in the guide cables and they do not have to be placed under a tension having an undesirably high value.

A preferred way of solving the problem is illustrated in FIGS. 4, 5, and 6. It is done by permitting the length of the guide cables between the top and bottom of the derrick 11 to change in accordance with the elevation of the traveling block 12 in the derrick. This is accomplished by suspending counterweights 13 from the lower ends of the diverging guide cables 14 below sheaves 15, over which the cables pass. The counterweights hang down into the substructure 16 that supports the derrick. The weight of each counterweight is one-half the maximum load expected to be exerted on its cable by lateral movement of the traveling block. As the traveling block moves up and down in the derrick, the counterweights will rise and fall slightly to allow the length of the cables inside the derrick to change. Therefore, the cables do not have to stretch.

A further feature of this invention is that if the traveling block starts to swing laterally in the derrick, the counterweights at the side toward which the traveling block moves are, in eflect, transferred to the other two cables so that the tension on those cables will be doubled in order to restrain the movement of the block. This is accomplished by connecting a piston 18 to the lower end of each cable above its counterweight and mounting that piston in a stationary fluid pressure cylinder 19 that is rigidly connected to the substructure. Each cylinder above and below its piston is filled with a hydraulic fluid. Also, the upper end of each cylinder is connected by a pipe 20 to the lower end of the diagonally opposite cylinder, as shown best in FIG. 6. Thus, the two pipes connecting each pair of cylinders cross each other. If the traveling block starts to swing in a direction from the left-hand cylinders to the right-hand cylinders, as shown in FIG. 5, the tension on the left-hand guide cables will start to raise their pistons and that will tend to force the fluid above those pistons through pipes 20 towards the bottoms of the right-hand cylinders, with the result that the pistons in the right-hand cylinders also will be raised so that the left-hand cables will be supporting both sets of counterweights. This means that the tension on each left-hand cable has been doubled and therefore they will keep the traveling block from swinging against the right-hand side of the derrick. The block is prevented in the same general way from swinging at right angles to the direction just mentioned.

Another advantage of this system is that at the same time that the tension on the pulled guide cables is doubled, the tension on the other two cables is relieved,

as indicated in FIG. 5, both by the fluid pressure below their pistons and by the fact that the traveling block moves toward the angular relieved cables and thereby no longer hold-s them taut. The derrick therefore is not subjected to any more vertical stress than if the traveling block were hanging in the center of the derrick and each guide cable were supporting only its own counterweight.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. Oil well drilling apparatus comprising a derrick, a traveling block suspended therein for movement up and down in the derrick, at least three guide cables suspended in the derrick from its top part in widely spaced locations around the traveling block, means at the bottom of the derrick for normally holding all of the cables taut, and means secured to the traveling block connecting it with the guide cables and movable up and down with the block, the guide cables diverging from the traveling block toward the top and bottom of the derrick for restraining lateral movement of the traveling block in the derrick.

2. Oil well drilling apparatus according to claim 1, in which said cable-holding means include means for loading only the guide cable or cables that are pulled sideways by lateral movement of the traveling block.

3. Oil well drilling apparatus according to claim 1, in which said cable-holding means include counterweights supported by the guide cables, and means for adding further tension to only the cable or cables that are pulled sideways by said lateral movement of the traveling block.

4. Oil well drilling apparatus according to claim 1, in which each of said guide cables is an endless cable, said cable-holding means are sheaves around which the cables extend, and sheaves mounted in the mast support the cables from the top part of the derrick.

5. Oil well drilling apparatus according to claim 1, in which said cable-holding means include counterweights supported by the guide cables, and fluid pressure means for adding further tension to only the cable or cables that are pulled sideways by said lateral movement of the traveling block.

6. Oil well drilling apparatus according to claim 5, in which said fluid pressure means include stationary fluid pressure cylinders containing pistons connecting said guide cables with said counterweights, and means for increasing fluid pressure in the cable end of any cylinder associated with a sideways-pulled cable to resist movement of the piston therein toward said end.

7. Oil well drilling apparatus according to claim 6, in which said pressure-increasing means for each cylinder includes a pipe connecting the cable end of that cylinder with the counterweight end of another of said cylinders.

8. Oil well drilling apparatus comprising a rectangular derrick, a traveling block therein, means for moving the traveling block up and down in the derrick, four guide cables suspended in the derrick from near the four corners of its top part, means at the bottom of the derrick near the four corners thereof for holding the cables taut, the cables converging from top and bottom of the derrick toward the traveling block, and traveling means secured to the traveling block connecting it with said cables and movable up and down them with the block.

9. Oil well drilling apparatus according to claim 8, in which said cable-holding means include a counterweight and a piston supported by each guide cable, a stationary fl-uid pressure cylinder containing each piston, crossed pipes connecting the top of each cylinder with the bottom of the diagonally opposite cylinder.

10. Oil well drilling apparatus according to claim 9, in which each counterweight is suspended from the ad- 5 6 jacent piston and weighs substantially half the maximum 3,209,827 10/1965 Lacy 175--7 load expected to be exerted on each cable by lateral 3,236,302 2/ 1966 Postlewaite 175-7 t th t lin bl k. movemen of e rave g 0c FOREIGN PATENTS References Cited 5 699,988 12/1964 Canada. UNITED STATES PATENTS 2 999 549 9 19 1 Stratton 175 5 EVON BLUNK, Primary Exam'mer- 3,114,420 12/1963 Wilde 1757 H. C. HORNSBY, Assistant Eaxminer.

Claims (1)

1. OIL WELL DRILLING APPARATUS COMPRISING A DERRICK, A TRAVELING BLOCK SUSPENDED THEREIN FOR MOVEMENT UP AND DOWN IN THE DERRICK, AT LEAST THREE GUIDE CABLES SUSPENDED IN THE DERRICK FROM ITS TOP PART IN WIDELY SPACED LOCATIONS AROUND THE TRAVELING BLOCK, MEANS AT THE BOTTOM OF THE DERRICK FOR NORMALLY HOLDING ALL OF THE CABLES TAUT, AND MEANS SECURED TO THE TRAVELING BLOCK CONNECTING IT WITH THE GUIDE CABLES AND MOVABLE UP AND DOWN WITH THE BLOCK, THE GUIDE CABLES DIVERGING FROM THE TRAVELING BLOCK TOWARD THE TOP AND BOTTOM OF THE DERRICK FOR RESTRAINING LATERAL MOVEMENT OF THE TRAVELING BLOCK IN THE DERRICK.

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