An electrically powered tool down in a borehole is suspended from a cable that also supplies electrical power to the tool. The cable has a conducting member of sufficient tensile strength to support the majority of the weight of the tool and an insulating layer surrounding the conducting member.
1. In combination with an electrically powered tool down in a borehole, a cable for suspending the tool in the borehole for supplying electrical power to the tool, the cable comprising:
a conducting member of sufficient tensile strength to support the majority of the weight of the tool; and
an insulating layer surrounding the conducting member.
2. The cable according to claim 1 wherein the conducting member comprises copper-clad steel.
3. The cable according to claim 1 wherein the conducting member comprises a beryllium-copper alloy.
4. The cable according to claim 1 wherein the conducting member has a sufficient tensile strength to support a 500 lb payload and its own weight over 20000 feet.
5. The cable according to claim 1 wherein the conducting member includes two or more separate electrically insulated conductors.
6. The cable according to claim 1 , further comprising
a chemically protective layer.
7. The cable according to claim 6 wherein the chemically protective layer is of metal.
8. The cable according to claim 1 , further comprising
a fiber-optic cable.
9. The cable according to claim 8 , further comprising
at least one beryllium copper conductor concentrically surrounding the fiber-optic cable.
10. The cable according to claim 8 , further comprising
an outer layer of the same material as the conducting member surrounding the insulating layer.