US3603718A

US3603718A - Electrical cable structure

Info

Publication number: US3603718A
Application number: US27342A
Authority: US
Inventors: Rudolf Karl Heinz Gedenk
Original assignee: Deutsche Texaco AG
Current assignee: Wintershall Dea Deutschland AG
Priority date: 1969-04-14
Filing date: 1970-04-10
Publication date: 1971-09-07
Anticipated expiration: 1988-09-07
Also published as: FR2039160B1; AT292815B; DE1918841C3; DE1918841B2; FR2039160A1; DE1918841A1

Abstract

Electrical cable structure that is adapted for downhole oil well use or for similar conditions. There are open channels under the sheath with gas permeable walls for dissipating accumulation of hydrocarbon gas.

Description

United States Patent [56] References Cited UNITED STATES PATENTS 1,883,648 10/1932 Emanueli I 72] Inventor Rudolf Karl Heinz Gedenk Celle, Germany [21 1 Appl. No. 27,342

174/1 16 X 174/47 UX 174/70 X 2,799,720 7/1957 Emanueli 3,149,199 9/1964 Pedrettiet a1. 3,517,110 6/1970 Morgan............ 3,526,086 9/1970 Morgan 2,910,524 10/1959 Schaflhauser...

Primary Examiner-Lewis l-l. Myers Assistant Examiner-A. T. Grimley Attorneys-Thomas l-l. Whaley and Carl G. Ries Apr. 10, 1970 [45] Patented Sept. 7, 1971 (7 3] Assignec Deuteehe Texaco Aktiengesellachalt Hamburg, Germany [32] Priority Apr. 14, 1969 [33] Germany [22] Filed 54 ELECTRICAL CABLE s'muc'rune 7Clalms,lDrawingFig.

ABSTRACT: Electrical cable structure that is adapted for downhole oil well use or for similar conditions. There are open channels under the sheath with gas permeable walls for diesipating accumulation of hydrocarbon gas.

[50] Field ol 24, 25,26, 27, 100, 116, 113, 110.8, 47,70R

ELECTRICAL CABLE STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a power supply cable, which in addition to conductors has within its sheathing a number of channels extending from one end of the cable to the other.

2. Description of the Prior Art Power supply cables of the general type disclosed in this application are know as illustrated by the disclosure of German Pat. No. DBP 902 988 where the channels serve for passing a cooling medium. However, in that German patent the channel walls are, made impermeable. It discloses channels that are formed by wire coils which are embedded in the fillers arranged between the conductors. The wire coils are made impermeable by coating them with tight material or by embedding them in a rubber compound.

SUMMARY OF THE INVENTION Briefly, the invention concerns an electrical power supply cable for use downhole in oil wells and the like which contain a range of heavy and light hydrocarbons under superatmospheric pressure. It comprises in combination three stranded conductors each having an electrically insulating coating thereon. It also comprises an outer sheathing constructed of an electrically insulating material that will withstand heavy hydrocarbon but is penetrable by gaseous hydrocarbons, and three tubular inserts spaced between said conductors and said sheathing to form open channels within said sheathing. The said inserts have freely permeable walls. And, it comprises permeable filler material filling the spaces within said sheathing surrounding said channels.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode contemplated by the inventor of carrying out the invention, and in connection with which there are illustrations provided in the drawing, wherein:

The FIG. of drawing is a schematic cross section view of a cable constructed according to the invention.

It is the object of the invention to provide power supply cables that polyolefins. However, resistant to hydrocarbon mixtures, such as petroleum. This problem is encountered, for example, where power supply cables are used for feeding submerged pumps installed in oil wells. In that case it cannot be avoided that the sheathing of the cable is in permanent contract with oil. Since the sheathing must be flexible, it is usually made of natural or synthetic polymers. These materials include some, such as rubber, that do not resist to any hydrocarbons. Others can protect the interior of the cable from heavy hydrocarbons but are penetrated by gaseous hydrocarbons. Such materials are, for example, chlorinated rubbers, polyvinyl chloride, and polyolefins. However, for a power supply cable exposed to hydrocarbon mixtures, it is essential that the insulations of the conductors inside the cable should be protected from all hydrocarbons including gaseous ones.

The invention achieves this object by a power supply cable having a sheathing impermeable to heavy hydrocarbons and being provided inside the sheathing with insulated conductors and with channels extending from one end of the cable to the other, the channel walls being permeable to gas, and the space between the sheathing, the channels, and the insulated conductors being filled with material permeable to gas. If these channels are left open to the atmosphere at one or both ends of the cable, any light hydrocarbons that have penetrated through the cable sheathing into the interior of the cable can enter the channels across the filling material and escape to the outside atmosphere. In this way, any buildup of gaseous hydrocarbons inside the cable and resultant destructive effect on the insulation of the conductors are prevented.

It may be noted that as an additional feature, the gaseous hydrocarbons present inside the channels could beremoved by suction or by means ofa flushing medium, such as inert gas.

The FIG. of drawing illustrates one embodiment of the invention without limiting the scope thereof. It shows a cross section of a cable structure according to the invention. There are three stranded conductors I that are each coated or covered by electrically insulating material 2. A cable sheathing 3 is constructed of flexible insulation that is material which will withstand the heavier hydrocarbons but is penetrable by gaseous hydrocarbons.

There is a filling material 4 that fills the spaces inside the sheathing 3 which surround the coated conductors l and three coils 5. These coils 5 form the walls of channels 6 within the cable for permitting free flow of any hydrocarbon gases that penetrate the sheathing layer 3.

The filling material 4 may be made of fibers or of an appropriate synthetic foam. However, if it is made of foam the cell walls must be perforated in order to gas through the material 4.

The channels 6 may be formed by metal coils 5, as illustrated, or perforated tubes (not shown), or similar inserts. Moreover, it may be feasible to introduce the gas-permeable filling material 4 between the cable sheathing 3 and the conductors l in such a way that the channel-shaped cavities 6 are left open as the cable is being constructed.

The cable sheathing 3 may, for example, consist of polyolefins, polyfluorinated hydrocarbons, polyamides, polyethers, etc. Furthermore, it might be protected by a surrounding metal wire netting (not shown) if desired.

While a preferred embodiment of the invention has been described above in considerable detail in accord and with the applicable statutes, this is not to be taken as limiting the invention but merely-as being descriptive thereof.

1 claim:

1. An electrical cable, comprising in combination at least one conductor having an electrically insulating coating thereon,

an outer sheathing of flexible electrically insulating material surrounding said conductor,

said sheathing being impervious to liquid hydrocarbons, and

at least one open channel within said sheathing for carrying gas away from the interior thereof.

2. An electrical cable according to claim 1 further including gas permeable material filling the spaces between said conductor, said sheathing and said channel.

3. A cable according to claim 2 wherein said combination comprises a plurality of said conductors.

4. A cable according to claim 3 comprising a power supply cable having three conductors, and

having three of said open channels.

5. An electrical power supply cable for use downhole in oil wells and the like containing a range of heavy and light hydrocarbons under superatmospheric pressure, comprising in combination three stranded conductors each having an electrically insulating coating thereon,

an outer sheathing constructed of an electrically insulating material that will withstand heavy hydrocarbons but is penetrable by gaseous hydrocarbons,

three tubular inserts spaced between said conductors and said sheathing to form open channels within said sheathing,

said inserts having freely permeable walls, and

permeable filler material filling the spaces within said sheathing surrounding said channels.

6. The combination according to claim 5, wherein said permeable filler material is fibrous.

7. The combination according to claim 5, wherein said permeable filler material is synthetic foam having perforated cell walls.

permit free passage of

Claims

1. An electrical cable, comprising in combination at least one conductor having an electrically insulating coating thereon, an outer sheathing of flexible electrically insulating material surrounding said conductor, said sheathing being impervious to liquid hydrocarbons, and at least one open channel within said sheathing for carrying gas away from the interior thereof.

4. A cable according to claim 3 comprising a power supply cable having three conductors, and having three of said open channels.

5. An electrical power supply cable for use downhole in oil wells and the like containing a range of heavy and light hydrocarbons under superatmospheric pressure, comprising in combination three stranded conductors each having an electrically insulating coating thereon, an outer sheathing constructed of an electrically insulating material that will withstand heavy hydrocarbons but is penetrable by gaseous hydrocarbons, three tubular inserts spaced between said conductors and said sheathing to form open channels within said sheathing, said inserts having freely permeable walls, and permeable filler material filling the spaces within said sheathing surrounding said channels.