The term Slickline relates to the use of a wire or braided line to convey downhole tools or equipment in a wellbore. The first use of wire in a wellbore was as a measuring device. In the construction of the early wells dug by hand, sticks were used to measure depth. The stick was laid on the ground and the distance/length stepped off. Occasionally, for important measurements a surveyor’s chain would be used. To create a hole in the ground, early drilling operations used a pointed tool on a rope. However, as the work progressed, the rope stretched and often broke. The length of the rope could not then be used as an accurate measure.

To overcome the weakness of rope, wire cable was used. By this time, a method had to be devised to measure the depth of the hole. Normally the hole had water in it to help soften up the dirt, clay sandstone or limestone rock. If the driller used a rope with markings, the rope would be wet as it came out of the hole and would rot while being rolled up on a winch type spool or drum. The drillers started using cable, but it was bulky and as it stretched going in the hole, the weight of the cable either broke it or stretched between the markings on the cable.

Slickline (and occasionally braided line) is commonly used in the following operations:

• Checking the production tubing drift
• Checking the build up of wax, scale or wellbore deposits
• Confirming the well depth or clearance to perforations
• Running and pulling plugs or flow control devices
• Opening and closing sliding side-doors or similar completion equipment
• Conducting pressure and temperature surveys using mechanical or electrical gauges and recorders
• Installing tubing pack-offs or similar completion devices
• Logging and perforating