Insulated electrical connection

May 7, 1935. j, v polk 2,000,716

INSULATED ELECTRICAL CONNECTION

Filed April 7, 1934

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ATTORNEY

Patented May 7, 1935

2,000,716 . UNITED STATES PATENT OFFICE

2,666,716 ’ INSULATED ELECTRICAL CONNECTION

James V. Polk, Dallas, Tex., assignor to Geophysical Service Inc., a corporation of New Jersey

Application April 7, 1934, Serial No. 719,493

Claims. (CL 255—28)

This invention relates to new and useful improvements in insulated electrical connections and it has particular reference to such connections in rotary drill pipes of the type employed 5 especially in drilling wells.

The principal object of the invention is to provide means to effect connection between the joints of drill stems, or pipes containing an electrical conductor whereby to avoid the difficul10 ties encountered heretofore when it became necessary to disconnect the joints of the drill stem in a well. The present invention maintains a suitably insulated electrical conductor within the drill pipe and is so adapted that the elec15 trical conductor is automatically broken at the joints when the drill pipe is disassembled and likewise, automatically reconnected when the drill pipe is reassembled. ’

The present invention has general application 20 in any operation where it is necessary to have an electrical conductor pass through a drill pipe in rotation and it has specific application to the method described in the U. S. Patent No. 1,927,664.

With the foregoing objects as paramount, the invention has particular reference to its salient features of construction and arrangement of parts which will become manifest as the description proceeds, taken in connection with the 30 accompanying drawing, wherein:—

Figure 1 is a vertical section of a rotary table and drill stem assembly similar to that illustrated in U. S. Patent No. 1,927,664 incorporating the improvements herein defined.

Figure 2 shows adjacent ends of a rotary drill pipe in fragmentary cross section embodying the present invention.

Figure 3 is a modified form of the present invention shown fragmentarily in vertical cross 40 section, and

Figure.4 is a view on lines 4—4 on Figure 3.

In Figure 1, the drill stem is designated by the character I which extends to the bottom of the hole and to which is secured a drill bit 2. 45 At the surface, the conventional rotary table is designated at 3 through which passes the conventional Kelly joint 4. Connected to the upper end Of the drill stem assembly is the conventional water swivel 5. A slip ring 6 insures con50 tinuous contact between the battery 7 and the tubular conductors 12 in drill stem ί so that an electric current may be caused to pass from the battery 7, through the tubular conductor 12 to the drill bit 2. The electric current then flows 55 into the earth around the bit 2, returning through a low resistance ground connection 8 through the ammeter 9 back to the battery 7.

If the voltage across the battery 7 is substantially constant, such as will be the case provided the battery is of sufficiently large capacity and S as will be indicated by a voltmeter ί 0, the amount of current flowing from the bit 4 into the ground will be determined by the resistance of the ground near the bit, because the greater portion of the electrical resistance in the circuit will be in the 10 vicinity of the bit 2. This is clearly described in the aforesaid Letters Patent No. 1,927,664.

Referring now particularly to the present invention, it will be observed in Figure 2 that the ends of the drill stem sections are joined to- 15 gether by tapered threads II. Within the sections of drill stem 1 there is provided tubular conductors 12 which are insulated from the inner walls of the drill pipe by the insulating liners 13, which may be made of synthetic resin, var- 20 nished cambric, asphaltum or other suitable material. In order to compensate for any variation in the threads, the ends of the sections of insulating material 13 are telescopically related, that is to say, the end of one section is reduced 25 to receive the end of an adjacent section as shown at a in Figure 2. _o

Due to a certain amount of wear on the threads, slippage at the threads when the pipe is rotating and because of irregularities in the length of the ³⁰sections in a large number of sections of drill pipe, it is necessary to provide an electrical contact at the joint in the pipe and which will be automatically adjustable to compensate for wear and variation In length, as well as to be free from ³⁵slippage while the drill pipe is rotating to prevent disruption, of the electrical circuit. An electrical contact at the joint such as shown in Figure 2 very satisfactorily overcomes the conditions above described and may be comprised of a coiled ⁴⁰spring (4 which abuts the adjacent ends of the inner tubular conductor (2. This spring may be made of bronze which has been found to be a suitable material.

Referring now to Figure 3, a modified example ^⁴⁵of the invention is shown in this figure and is comprised primarily of a metallic sleeve 15 which is in sections, being divided into upperand lower sections at b at which point is also the separating line between the drill stem sections ⁵⁰(6 which are joined together by the tapered threads (7 as in the preceding case.

Embedded within the upper section of the sleeve 15 is a tubular insulating liner (8 which is in telescopic relationship with a similar insulat2,000,716 ing liner (9. It is understood that in screwing . the sections of drill stem together, the sections of insulating material 18 and 19 must be capable of independent rotation, yet the electrical cir5 cuit through the joint must not be disrupted. In associating the insulated sections 18 and 19, an annular recess 20 is left intermediate the ends of the sections and in which is disposed metallic rings 21 and 22. A coiled spring 23 is interposed 10 between the rings 21 and 22 and serves to maintain continuous electrical connection between the ends of the conductors through which current is passed through the drill stem assembly and to which reference will be made presently.

A metallic wire or rod 24, preferably of copper, is surrounded by an insulated covering 25 and through the medium of a tubular sheath 26, providing further protection, the conductor thus provided is secured into the upper section of the 20 sleeve 15. As apparent, the wire or rod 24 continues downward into the insulating liner 18 to the metallic ring 21 to which it is connected. Similarly, an electrical conductor in the form of a wire or rod 2T, suitably covered by an insulating 25 material 28, is secured by means of the sheath to the lower section of the sleeve (5. The conductor 27 continues into the lower section of the insulating liner 19 and is connected to the metallic ring 22 companion to the ring 2i.

It is apparent from the foregoing that when it is required to dismantle the drill stem assembly the electrical connection at the joints will not be disturbed since the upper section of the sleeve 15 is in fixed relation to the upper drill stem 35 section and the insulating liner 18 rotates therewith.

When the drill stem sections are separated, there are no projecting elements which are likely to be injured by the rough handling to which 40 the drill stem is usually subjected. Accordingly, it is readily seen that by the use of the present invention, a completely connected conductor running the entire length of the drill stem assembly is obtained.

In order that the insulating liner 13, as shown in Figure 1, will not be subjected to any strain or other detrimental effects resulting from the rotation of the drill stem assembly at the point where the drill bit 2 is joined thereto, the insulat50 ing liner is increased in diameter at its lower end as indicated by the character c so as to form a shoulder d against which the lower end of the drill stem abuts. The enlarged portion c of the liner 13 is both interiorly and exteriorly threaded.

The inner threads jointly embrace the lower extremity of the conductor 12 and the threaded pin of the bit 2. A threaded connection 31 embraces the lower end of the drill stem and the internally threaded portion of the insulating liner

13. This is borne out in the lower portion of Figure 1. This arrangement maintains solid relationship between the bit 2 and the drill stem yet insures positive insulation between the metallic parts of the assembly and the bit.

Manifestly, the construction shown is capable of some modification and such modification as is considered within the scope and meaning of the appended claims is also considered within the spirit and intent of the invention.