Summary Of The Disclosure

This disclosure relates to a drilling derrick of the type used to drill oil and g wells and particularly relates to an improved crown block/traveling block system

use with drilling derricks.

Deep oil and gas wells are drilled utilizing a derrick having a drawworks with line extending therefrom. The typical derrick system has a crown block at the to

The line from the drawworks extends up over the crown block and then vertica downwardly within the derrick to a traveling block. The traveling block provides mea for attachment to equipment used in drilling wells, such as a swivel and hook unit. T line extends from the traveling block back over the crown block and then is attach to a tie down or deadline anchor. Usually, the crown block and traveling block ha multiple sheaves so that the line loops a number of times between the crown block a the traveling block so as to provide mechanical advantage necessary to lift the hea load encountered in drilling operations. When it is considered that oil and gas wel are frequently drilled to a depth of 10,000 feet or greater, the weight of drilling tools casing extending down this depth (almost two miles) becomes enormous. Therefor

in order to support such great loads, the crown block system and traveling blo system are very carefully engineered. Further, as above mentioned, in order to li

the diameter of line that must be employed to lift such great loads, the crown blo and traveling blocks are typically formed of a number of sheaves, each sheave rotatin about a common axis and independently of other sheaves since in the use of multipl cable loops between the crown block and traveling block the sheaves rotate at differe

speeds when line is being wound onto a drawworks or when the drawworks is lettin out line so as to lower the traveling block.

For background information relating to crown block and traveling bloc assemblies and improved means of using such apparatus in drilling oil and gas well reference may be had to United States Patent Nos. 4,796,863; and 4,836,300. Pate

No. 4,796,863 is entitled "Dual Cluster Crown Block" and Patent No. 4,836,300 i entitled, "Method of Performing Drilling Operations From A Derrick."

A problem encountered in drilling operations is that extremely heavy weights ar born by the derrick and the drawworks only at a small percent of the portion of th entire drilling operation. In normal drilling operations wherein drill pipe is raised an lowered as necessary to change bits and to permit the drill pipe to move verticall downwardly as the hole is drilled, the weight encountered by the derrick and the drawworks is not excessive. When it is necessary to run casing at great depths or when the depth of the well has increased to a point where the length of the drill pipe is great, then greater weight is applied to the derrick and the drawworks. Since the derrick and drawworks must be arranged to support the maximum loads but wherein such maximum loads are only encountered a small percent of the time in drilling, inefficiency in the design and operation of derricks and drawworks developes.

It is an object of this disclosure to provide an improved crown block/traveling

block system for a well drilling derrick that allows the use of a smaller drawworks for

efficient drilling operation over most of the drilling time required for atypical oil and gas well, but which also provides the capacity to run casing at great depth with the heavy loads encountered with the same drawworks and drilling line.

The improved crown block/traveling block system for a well drilling derrick of this disclosure employs a derrick with a support structure adjacent the derrick top, the derrick having a drawworks with a fast line extending therefrom. An elevationally

stationary multi-sheave upper crown block is secured to the derrick support structure

vertically over the well borehole. An elevationally stationary multi-sheave lower crow block is secured to the derrick support structure in tandem with and below the upp crown block.

An elevationally moveable multi-sheave traveling block is positioned within th derrick below the crown block. The traveling block includes means to support a apparatus for attachment to drilling equipment, such as a swivel and hook unit.

A multi-sheave intermediate block is employed and is used in two modes. I the first mode the intermediate block is attached to the derrick support structure belo the lower crown block so that in the first mode the intermediate block forms a portio of a three-block crown block cluster. In the second mode the intermediate block i detached from the support structure and is secured to the upper end of the travelin block. In the second mode the intermediate block and traveling block form a two-bloc traveling block cluster.

The fast line extending from the drawworks is looped in a route that extend over a fast line sheave, over the top of the upper crown block, around the bottom o the traveling block, again over the top of the upper crown block, then down around th bottom of the intermediate block, then over the top of the lower crown block and the over a deadline sheave to a deadline anchor. The route being repeated dependin

upon the number of sheaves in the blocks. In such system, in the first mode the upper crown block, lower crown block an intermediate block form an elevationally stationary crown block cluster. In the secon mode the intermediate block and the traveling block form a traveling block cluster.

In the preferred arrangement of the improved crown block/traveling bloc system the sheaves of the lower crown block are of smaller diameter than the sheave

of the upper crown block, and the sheaves of the intermediate block are of smalle

diameter than the sheaves of the traveling block. As an illustration of one means practicing the concept of this disclosure, the diameter of the sheaves of the uppe crown block and the lower crown block may be essentially the same, whereas th diameter of the sheaves of the lower crown block and the intermediate block may b substantially the same but smaller in diameter than that of the sheaves of the uppe crown block and the traveling block.

In the first mode, wherein the intermediate block forms a part of a crown bloc cluster, the traveling block functions in the normal manner with the mechanical advantage applied to the line extending from the drawworks being determined by the number of sheaves in the traveling block and correspondingly the number of loops in the route of the line. Thus, in the first mode the traveling block functions in the normal manner of the usual oil well drilling application, and efficiency is obtained in that the crown block serves to lift the normal, non-excessive weights encountered in most oil well drilling activities. However, in the second mode where the intermediate block forms a part of the traveling block cluster, multiple mechanical advantage is obtained by the cable routing so that greater weights can be lifted with the same tension applied

to the line.

The unique system of utilizing plural crown blocks and an intermediate block that can function either as a part of the crown block cluster or as a part of a traveling block cluster thereby enables the design of the derrick and drawworks for maximum efficiency of weight lifting capability. In addition, the tandem system of block interchange as herein disclosed can be very economically and efficiently changed from

mode one to mode two, since no rerouting of the line is required and the intermediate block can be raised and lowered by the drawworks system itself.

A better understanding of this disclosure will be had by reference to th following description and claims, taken in conjunction with the attached drawings.

Description of the Drawings

Figure 1 is a diagrammatic illustration of the components of a derrick used f drilling oil and gas wells, the derrick not being shown but the horizontal derrick suppo structure which is adjacent the derrick upper end is illustrated and showing an upp crown block, a lower crown block and an intermediate block supported in vertic tandem arrangement to the derrick support structure. In Figure 1 the intermediat block is in mode one wherein it is affixed to the derrick support structure and forms part of the crown block cluster.

Figure 2 is a diagrammatic view as in Figure 1 but showing the intermediat block affixed to the traveling block to thereby become a part of a traveling bloc cluster. The apparatus is used in Figure 1 during the usual drilling operations and i

Figure 2 during that portion of the drilling operations wherein extremely heavy load are carried by the traveling block cluster.

Figure 3 is a diagrammatic illustration of the first mode as shown in Figure 1 showing diagrammatically the routing of the line over the upper crown block, intermediate block, lower crown block and traveling block as is utilized in normal drilling operations.

Figure 4 is a diagrammatic view as in Figure 3 but showing the intermediate block formed as a part of the traveling block cluster in the cable arrangement when extremely heavy weights must be supported.

Description Of The Preferred Embodiment

Referring to the drawings and first to Figure 1 , a crown block/traveling bloc system for a well drilling derrick is shown. A derrick used for drilling oil or gas well

is generally a four-sided vertical upwardly tapered structure and is very well known i

industry. Adjacent the top of the derrick a horizontal support structure 10 is utilized t provide a base for supporting a crown block assembly, generally indicated by th numeral 12. In the embodiment of Figure 1 the crown block assembly includes a upper crown block 14, a lower crown block 16 and an intermediate crown block 18.

The upper crown block 14 is formed of a plurality of sheaves 19, three bein shown, it being understood that the illustration of three sheaves is by way of exampl only as the number of sheaves can vary depending upon the design of the derrick an the crown block/traveling block system. The upper crown block 14 is shown affixe to support structure 10 by structural members 22, which is by way of example only a the structural arrangement of the derrick upper portion including support structure 1 and structural members 22 may vary considerably. Lower crown block 16 is positioned in tandem with and directly below uppe crown block 14. The lower crown block is formed of a series of sheaves (three bein shown) that are individually supported about axle 24.

Positioned in tandem and vertically directly below upper crown block 14 and lower crown block 16 is an intermediate block 18 that includes a plurality of sheaves

28 (three being shown) that independently rotate about an axle 26. Intermediate block

has opposed side plates 30 and 32, the side plates rotatably supporting axle 26.

Positioned between side plates 30 and 32 and below sheaves 28 is a spacer 34.

Formed as a part of support structure 10 and extending downwardly therefrom and

vertically below the upper and lower crown blocks 14 and 16 is a fixed spacer 3

Plates 30 and 32 extend to either side of fixed spacer 36 and when intermediate bloc

18 is in the upward position as shown in Figure 1, a pin 38 extends through opening in plates 30 and 32 and through fixed spacer 36 to removably lock intermediate bloc

18 in the upward position. Therefore, in the arrangement as in Figure 1 , a crown bloc cluster is formed of upper crown block 14, lower crown block 16 and intermediat block 18.

The derrick includes, as an integral part of a well drilling system, a drawwork indicated by spool 40 having a fast line 42 wound thereon. Line 42 extends over a fas line sheave 44 rotatably secured to support structure 10 and over a sheave 19 formin

a part of upper crown block 14. Line 42 extends further in a looped route to form crown block/traveling block system to be described subsequently.

Positioned vertically below the crown block cluster is a traveling block, generally indicated by the numeral 46. The traveling block is formed by opposed parallel plates 48 and 50 that supports an axle 52 about which a plurality of individual sheaves 54 rotate. Plates 48 and 50, below sheaves 54, support a swivel and hook unit 56 that

is exemplary of equipment attachment means used in drilling oil and gas wells. The

upper ends of plates 48 and 50 are spaced apart and have an opening 58 therein that can be aligned with an opening 60 in the bottom of intermediate block spacer 34. Line 42 extends over fast line sheave 44 and loops over the top of one of the sheaves 19 of upper crown block 14. Line 42 loops within the upper crown block cluster and below the traveling block sheaves 54 to thereby support the traveling block.

Line 42 provides multiple passes between the upper crown block cluster and lower

crown block 46, and finally the line passes over a deadline sheave 62 affixed to the

derrick support structure 10, and line 42 then attaches to a deadline anchor or ti down 64.

Referring to Figure 3, an example of the position of line 42 on the sheave making up upper crown block 14, lower crown block 16, intermediate block 18 an

traveling block 46 is diagrammatically illustrated. Line 42 loops over fast line sheav

44, over the top of upper crown block 14, around the bottom of traveling block 46 again over the top of upper crown block 14, then down around the bottom o intermediate block 18, then over the top of lower crown block 16, and then ove deadline sheave 62 to deadline anchor 64. The route of line 42 is repeated a numbe

of times depending upon the number of sheaves in the blocks to provide the lifting capabilities required according to the derrick design. Generally, the tensile stress in

line 42 is determined by the weight imposed on traveling block 46 divided by the number of lines extending from traveling block 46 to the crown block cluster. In the arrangement illustrated in Figure 1 which shows eight lines between traveling block 46 and the crown block cluster would mean that the total tension load on line 42, ignoring dynamics, would be 1/8 of the load on traveling block 46.

In Figure 3 the portion of line 42 that moves is indicated by 42A and the portion that does not move is indicated by 42B.

The system of Figures 1 and 3, mode one, is used during the majority of drilling operations wherein drill pipe is being run in and out of the hole or where casing is run

at shallower depths. When very heavy loads are required, such as when running casing into a deep oil or gas well, the system of this disclosure is easily varied to

accommodate such increased weights by use of a mode two in which the crown block/traveling block system is arranged as shown in Figure 2. In Figure 2,

intermediate block 18 has been moved out of the crown block cluster and is attache to traveling block 46 to form a traveling block cluster. This is easily accomplished b removing pin 38 to allow intermediate block 18 to move downward, which can b accomplished, when there is no load on the traveling block, by releasing line 42 fro the drawworks. A pin 66 is then inserted through openings 58 in the top of plates 4 and 50 and through opening 60 in the bottom of spacer .34. This arrangement the couples intermediate block 18 to the traveling block, providing a traveling block cluster

In mode one as shown in Figures 1 and 3, the intermediate block 18 does no move and therefore does not experience wear and tear. The cable route for mode two is shown diagrammatically in Figure 4. The cabl route is the same, that is, line 42 is not rerouted in any way whatsoever - only the location of intermediate block 18 is changed. However, such change results in a significant difference in the weight supporting capability of the system which, as previously stated, is limited by the tensile strength of line 42. Note that in the arrangement of Figure 4, mode two, and assuming the same number of sheaves as illustrated in Figures 1 and 2, that is, wherein each of the blocks include four independently rotatable sheaves, there is a total of sixteen lengths of line extending from the traveling block cluster to the crown block cluster meaning that, ignoring dynamics, a maximum load sixteen times the tensile strength limit of line 42 can be supported. In other words, by the expedient of moving intermediate block 18 from one location to another, the weight supporting capabilities of the crown block/traveling

block system for a derrick can be doubled without increasing the tensile load on line

42 and without the necessity of rerouting the line or for adding or taking away any piece of equipment. This advantage is accomplished by the movement of the

intermediate block 18 from one position to another.

In Figure 4 the portion of line 42 that moves is indicated by 42C and the portio that does not move is indicated by 42D.

The claims and the specification describe the invention presented and the term

that are employed in the claims draw their meaning from the use of such terms in th specification. The same terms employed in the prior art may be broader in meanin than specifically employed herein. Whenever there is a question between the broade definition of such terms used in the prior art and the more specific use of the term herein, the more specific meaning is meant. While the invention has been described with a certain degree of particularity, i is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.