Torque-balanced, gas-sealed wireline cables

Abstract

A torque-balanced, gas-blocking wireline cable and a method of making the cable includes an electrically conductive cable core for transmitting electrical power and surrounding inner and outer layers of a plurality of armor wires. Gas blocking is achieved by placing a soft polymer layer over the core before the inner wires are cabled thereon. The inner wires imbed partially into the soft polymer layer such that no gaps are left between the inner wires and the core. A second soft polymer layer is optionally extruded over the inner wires before the outer wires are applied. The second soft polymer layer fills any spaces between the inner and outer wire layers and prevents pressurized gas from infiltrating between the wires. The inner wires have larger diameters than the outer wires such that the inner wires carry approximately 60% of the load and torque imbalance is prevented.

We claim: 
     
         1 . A cable, comprising:
 an electrically conductive cable core for transmitting electrical power;   a first layer of polymer material surrounding said cable core;   an inner layer of a plurality of first armor wires surrounding said cable core, said first armor wires being imbedded in said first layer to prevent gaps between said first armor wires and said cable core; and   an outer layer of a plurality of second armor wires surrounding said inner layer, said second armor wires having a smaller diameter than a diameter of said first armor wires for preventing torque imbalance in the cable.   
     
     
         2 . The cable of  claim 1  wherein said first armor wires carry approximately 60% of a load applied to the cable. 
     
     
         3 . The cable of  claim 1  including a second layer of polymer material surrounding said inner layer, said outer layer surrounding said second layer. 
     
     
         4 . The cable of  claim 3  including a third layer of polymer material surrounding said outer layer. 
     
     
         5 . The cable of  claim 1  wherein said second armor wires are stranded wires. 
     
     
         6 . The cable of  claim 1  wherein said polymer material of said first layer is formed from at least one of: a polyolefin or olefin-base elastomer material; a thermoplastic vulcanizate material; a silicone rubber; an acrylate rubber; a soft engineering plastic; a soft fluoropolymer material; a fluoroelastomer material; and a thermoplastic fluoropolymer material. 
     
     
         7 . The cable of  claim 1  wherein said cable core includes another polymer material having a higher melting point than a melting point of said polymer material of said first layer. 
     
     
         8 . A cable, comprising:
 an electrically conductive cable core for transmitting electrical power;   a first layer of polymer material surrounding said cable core;   an inner layer of a plurality of first armor wires surrounding said cable core, said first armor wires being imbedded in said first layer to prevent gaps between said first armor wires and said cable core;   a second layer of polymer material surrounding said inner layer; and   an outer layer of a plurality of second armor wires surrounding said second layer, said second layer preventing gaps between said first armor wires and said second armor wires, said second armor wires having a smaller diameter than a diameter of said first armor wires for preventing torque imbalance in the cable.   
     
     
         9 . The cable of  claim 8  wherein said first armor wires carry approximately 60% of a load applied to the cable. 
     
     
         10 . The cable of  claim 8  including a third layer of polymer material surrounding said outer layer. 
     
     
         11 . The cable of  claim 8  wherein said second armor wires are stranded wires. 
     
     
         12 . The cable of  claim 8  wherein said polymer materials of said first and second layers are formed from at least one of: a polyolefin or olefin-base elastomer material; a thermoplastic vulcanizate material; a silicone rubber; an acrylate rubber; a soft engineering plastic; a soft fluoropolymer material; a fluoroelastomer material; and a thermoplastic fluoropolymer material. 
     
     
         13 . The cable of  claim 8  wherein said cable core includes another polymer material having a higher melting point than a melting point of said polymer materials of said first and second layers. 
     
     
         14 . A method of forming a cable, the method comprising:
 providing an electrically conductive cable core for transmitting electrical power;   surrounding the cable core with a first layer of polymer material;   providing a plurality of first armor wires and winding the first armor wires around the first layer to form an inner layer of the first armor wires imbedded in the first layer to prevent gaps between the first armor wires and the cable core; and   providing a plurality of second armor wires and winding the second armor wires around the inner layer to form an outer layer of the second armor wires, said second armor wires having a smaller diameter than a diameter of said first armor wires for preventing torque imbalance in the cable.   
     
     
         15 . The method of  claim 14  including extruding the first layer onto the cable core. 
     
     
         16 . The method of  claim 14  including surrounding the inner layer with a second layer of polymer material. 
     
     
         17 . The method of  claim 16  including surrounding the outer layer with a third layer of polymer material. 
     
     
         18 . The method of  claim 17  including extruding the second layer onto the inner layer and extruding the third layer onto the outer layer. 
     
     
         19 . The method of  claim 14  including providing the cable core with another polymer material having a higher melting point than a melting point of the polymer material of the first layer. 
     
     
         20 . The method of  claim 14  including forming the second armor wires as stranded wires.