Managing strain on a downhole cable

Abstract

Techniques for managing strain on a downhole cable, such as a slickline or wireline, include a wire coupled with a communication line, such as a fiber optic cable or metallic (or non-metallic) conductor. In one example, a downhole cable includes a wire to support a downhole tool string; and a communication line non-linearly coupled with the wire, the communication line sized to communicate instructions, that include at least one of logic or data to the downhole tool, and elongate based on an axial force that acts on the downhole cable.

1 . A downhole cable, comprising:
 a wire to support a downhole tool string; and   a communication line non-linearly coupled with the wire, the communication line sized to communicate instructions, that comprise at least one of logic or data to the downhole tool, and elongate based on an axial force that acts on the downhole cable.   
     
     
         2 . The downhole cable of  claim 1 , wherein the communication line comprises at least one of a fiber optic line or a metallic conductor. 
     
     
         3 . The downhole cable of  claim 1 , wherein the wire comprises a composite material. 
     
     
         4 . The downhole cable of  claim 3 , wherein the communication line is non-linearly embedded in a matrix of the composite material. 
     
     
         5 . The downhole cable of  claim 4 , wherein the communication line is non-linearly embedded in the matrix of the composite material in a helical or zig-zag path. 
     
     
         6 . The downhole cable of  claim 1 , wherein the wire comprises a flexible rod, and the communication line is non-linearly wrapped around the flexible rod. 
     
     
         7 . The downhole cable of  claim 6 , further comprising a coating that at least partially covers the communication line and the flexible rod. 
     
     
         8 . The downhole cable of  claim 7 , wherein the coating comprises polyether ether ketone. 
     
     
         9 . The downhole cable of  claim 1 , wherein for a particular portion of the downhole cable, a length of the communication line that extends between ends of the particular portion is greater than a length of the wire that extends between the ends of the particular portion. 
     
     
         10 . The downhole cable of  claim 1 , wherein a value that defines an allowable strain of the wire is greater than a value that defines an allowable strain of the communication line. 
     
     
         11 . The downhole cable of  claim 1 , wherein a diameter of the downhole cable is about 0.138 inches. 
     
     
         12 . The downhole cable of  claim 1 , wherein the wire comprises polyphenylene sulfide. 
     
     
         13 . The downhole cable of  claim 1 , wherein the downhole cable comprises a slickline, and the wire is a monofilament wire. 
     
     
         14 . The downhole cable of  claim 1 , wherein the downhole cable comprises a wireline, and the wire comprises a braided wire. 
     
     
         15 . A method of managing strain on a downhole cable, comprising:
 running a downhole tool coupled to a downhole cable into a wellbore, the downhole cable comprising a wire and a communication line non-linearly coupled with the wire;   operating the downhole tool in the wellbore by transmitting, on the communication line, instructions that comprise at least one of logic or data between the downhole tool and a terranean surface;   receiving a force in an axial direction on the downhole cable; and   in response to the received force, elongating the communication line from a substantially non-linear position toward a substantially linear position.   
     
     
         16 . The method of  claim 15 , wherein the communication line comprises at least one of a fiber optic line or a metallic conductor. 
     
     
         17 . The method of  claim 15 , wherein the communication line is non-linearly embedded in a matrix of a composite material. 
     
     
         18 . The method of  claim 17 , wherein elongating the communication line from a non-linear position toward a linear position comprises elongating the communication line from a helical or zig-zag position toward the substantially linear position. 
     
     
         19 . The method of  claim 15 , further comprising:
 receiving a second force in the axial direction on the downhole cable that is less than the received force; and   in response to the second force, shortening the communication line toward the substantially non-linear position.   
     
     
         20 . The method of  claim 15 , wherein the wire comprises a flexible rod, and the communication line is non-linearly wrapped around the flexible rod. 
     
     
         21 . The method of  claim 20 , wherein the downhole cable further comprises a coating that at least partially covers the communication line and the flexible rod. 
     
     
         22 . The method of  claim 15 , wherein for a particular portion of the downhole cable, a length of the communication line that extends between ends of the particular portion is greater than a length of the wire that extends between the ends of the particular portion. 
     
     
         23 . The method  claim 15 , wherein the logic or data comprises values associated with telemetry data. 
     
     
         24 . A downhole conductor, comprising:
 a wire that extends a first length between a first end of the downhole conductor and a second end of the downhole conductor, the wire sized to support a downhole tool string in a wellbore; and   a data conductor to transmit at least one of logic or data with the downhole tool string and coupled with the wire, the data conductor extending a second length between the first end of the downhole conductor and the second end of the downhole conductor, the second length greater than the first length.   
     
     
         25 . The downhole conductor of  claim 24 , wherein the data conductor is embedded in a helical path through a composite material of the wire. 
     
     
         26 . The downhole conductor of  claim 25 , wherein the composite material comprises a single homogenous tension member, and the data conductor is wound in a helical path around the member. 
     
     
         27 . The downhole conductor of  claim 26 , further comprising a protective coating wrapped around the data conductor and the tension member. 
     
     
         28 . The downhole conductor of any one of claims  claim 24 , wherein the data conductor comprises an optical fiber. 
     
     
         29 . The downhole conductor of  claim 24 , wherein each of the wire and the data conductor comprise respective distal ends that are coterminous with the first end of the downhole conductor and respective proximal ends that are coterminous with the second end of the downhole conductor. 
     
     
         30 . The downhole conductor of  claim 24 , wherein the downhole conductor comprises a slickline, and the wire comprises a single homogeneous wire, and the data conductor comprises a fiber optic conductor.