DRILL COLLAR

BACKGROUND OF THE INVENTION

Drill collars are constructed in various forms and are designed to withstand considerable axial loading and tension forces and to withstand high torque and "jar" loads. Examples of different forms of drill collars and other tubing members including some of the general structural and operational features oi the instant invention are disclosed in U.S. patent Nos. 2,352,412, 2,949,843, 3,109,501, 3,318,398, 3,420,323, 3,480,094, 3,588,199, 3,848,683, 4,060,286 and 4,156,374. SUMMARY OF THE INVENTION The drill collar of the instant invention comprises a thick walled tubing member and includes longitudinally spaced zones of different outside diameters with the larger outside diameter portions including end zones thereof each equipped with a circumferentially extending band defined by a build-up of hard metal heat fused thereon. The bands define still further larger diameter zones of the drill collar and function, in conjunction with the smaller diameter portions of the drill collar, to greatly reduce friction between the external surfaces of the drill collar and an associated well bore.

The drill collar is also constructed in a manner to withstand heavy axial compression and axial tension loads as well as "jar" forces.

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The main object of this invention is to provide a drill collar which will appreciably reduce frictional resistance between the drill collar and an associated well bore. Another object of this invention is to provide a drill collar constructed in a manner which will allow smaller pressure loss while circulating associated drilling mud.

Another important object of this invention is to provide a drill collar which will be capable of exerting greater weight on an associated bit.

A further object of this invention is to provide a drill collar which is easier to handle on the derrick and thereby reduces accidents.

Yet another object of this invention is to provide a drill collar which tends to stay cleaner on its exterior due to the turbulance of circulating drilling mud around the large outside diameter areas of the drill collar.

Still another object of this invention is to provide a drill collar which will facilitate wash over operations with less effort.

Another important object of this invention is to provide a drill collar which will reduce metal fatigue in the areas of connection of adjacent box and pin ends of adjacent drill collars.

A final object of this invention to be specifically enumerated herein is to provide a

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drill collar in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to use, so as to provide a device that will be economically feasible, long lasting and relatively trouble-free in operation. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an elevational view of a drill collar constructed in accordance with the present invention;

Figure 2 is an enlarged fragmentary elevational view of adjacent end portions of adjacent drill collars as illustrated in a formation having a well bore formed therein; Figure 3 is an enlarged fragmentary vertical sectional view taken substantially upon the plane, indicated by the section line 3—3 of

Fig. 1;

Figure 4 is an enlarged fragmentary sectional view taken substantially upon the plane indicated by the section line 4—4 of Fig. 1;

Figure 5 is an enlarged fragmentary sectional view taken substantially upon the plane indicated by the section line 5—5 of Fig. 1; and

Figure 6 is a horizontal sectional view taken substantially upon the plane indicated by the section line 6—6 of Fig. 4.

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DETAILED DESCRIPTION OF THE INVENTION

Referring now more specifically to the drawings, the numeral 10 generally designates a drill collar section constructed in accordance with the present invention. The drill collar section 10 comprises an elongated cylindrical member 12 including internally and externally threaded box and pin end sections 14 and 16, a plurality of longitudinally spaced and extending intermediate sections 18, and a plurality of longitudinally spaced and extending joining sections 20 extending between adjacent intermediate sections 18 and between each end section 14 and 16 and the adjacent intermediate section 18. In addition, a short elongated section 22 extends between the end section 14 and the adjacent end of the adjacent joining section 20.

The base end sections 14 and 16 may be substantially 7-3/4" in outside diameter, the intermediate sections 18 may be 7-3/4" and therefore the same outside diameter as the end sections 14 and 16 and the joining sections 20 may be 6-3/4" in diameter. The short section 22 may be substan¬ tially 7" in outside diameter and therefore slightly larger in diameter than the joining sections 20 and smaller in diameter than the end and intermediate sections 14, 16 and 20.

The end section 16 includes a reduced diameter and tapering externally threaded pin 24 and the end section 14 includes an internally

threaded recess 28 into which the pin 24 of an adjacent drill collar may be threadingly seated.

All of the above referred to components of the drill collar section 10 are integrally formed.

The axial ends of the intermediate sections 18 and the axial ends of the end sections 14 and 16 adjacent the sections 20 include circum¬ ferential rings or bands 30 which are built up on the cylindrical member 12 by hard metal heat fused thereon. The external surfaces of the bands 30 are machined smooth to cylindrical configuration coaxial with the central bore 32 formed through the cylindrical member 12 and the other cylindrical external surfaces of the cylindrical member 12 comprising the sections 14, 16, 18, 20 and 22. The bands 30 increase the diameter of the sections 14, 16 and 18 by only 1/4", each band 30 defining an effective increase in radius of only 1/8". Accordingly, the outside diameters of the bands 30 is substantially 8".

In addition to the bands 30, the section 22 includes a circumferentially extending zone 34 thereon at the axial end thereof joining with the adjacent section 20 and zone 34 is radiused and is approximately 1/4" in outside diameter greater than the outside diameter of the section 22. Accordingly, the zone 34 is substantially 7-1/4" in outside diameter and defines a slip retaining ring to facilitate handling of the cylindrical member 12.

The drill collar section 10 is designed to afford the most weight to bottom hole assemblies with shorter length and easier handling than conventional bottom hole assemblies. The drill collar section 10 may be run in compression with significantly less wall contact on the bore hole than other drill collars and, therefore, the drill collar sections 10 greatly reduce the chances of differential pressure sticking. The drill collar sections 10 do not experience as much wall contact as conventional drill collars and, therefore, experience a reduction of required torque and a reduction of drag in the bore hole.

The drill collar section 10 is to be made of the highest quality steel and affords stronger tool joint connections without increases in weight over the weight of conventional drill collars to insure trouble-free connection problems. The drill collar sections 10 are handled with elevators and slips without the need for safety clamps and, accordingly, less time is required to handle a bottom hole assembly. Further, the hard metal banding 30 may be renewed as needed at less expense than "changing out" stabilizers. It is recommended that three conventional drill collars be run with approximately 15 drill collar sections 10 in order to afford a sufficient amount of bottom hole weight and a shorter bottom hole assembly.