Wireline (cabling)

In the oil and gas industry, the term wireline usually refers to the use of multi-conductor, single conductor or slickline cable, or "wireline", as a conveyance for the acquisition of subsurface petrophysical and geophysical data and the delivery of well construction services such as pipe recovery, perforating, plug setting and well cleaning and fishing. The subsurface geophysical and petrophysical information results in the description and analysis of subsurface geology, reservoir properties and production characteristics.

Associated with this, "wireline logging" is the acquisition and analysis of geophysical and petrophysical data and the provision of related services provided as a function of along-hole depth.

There are four basic types of wireline: multi-conductor, single conductor, slickline and braided line. Other types of wireline include sheathed slickline and fibre-optic lines.

Multi-conductor lines consist of external armor wires wound around a core of typically 4- or 7-conductors. The conductors are bound together in a central core, protected by the outer armor wires. These conductors are used to transmit power to the downhole instrumentation and transmit data (and commands) to and from the surface. Multi-conductor cables are used primarily in open- (and cased-) hole applications. Typically they have diameters from 0.377 inches (9.6 mm) to 0.548 inches (13.9 mm) with suggested working loads from 6.6 to 20 thousand pounds-force (29,000 to 89,000 N). (Note that wireline diameters and performance characteristics are typically expressed in imperial units.) Multi-conductor cables can be sheathed in smooth polymer coverings but are more commonly open wound cables.

Single-conductor cables are similar in construction to multi-conductor cables but have only one conductor. The diameters are usually much smaller, ranging from 1⁄10 inch (2.5 mm) to 5⁄16 inch (7.9 mm) and with suggested working loads of 800 to 7,735 lbf. Because of their size, these cables can be used in pressurized wells making them particularly suited for cased hole logging activities under pressure. They are typically used for well construction activities such as pipe recovery, perforating and plug setting as well as production logging and reservoir production characterization such as production logging, noise logging, pulsed neutron, production fluid sampling and production flow monitoring.

Slickline is a smooth single strand of wireline with diameters ranging form 0.082" to 0.160". Slickline has no conductor (although there are specialized polymer coated slicklines and tubing encapsulated (TEC) slicklines). They are used for light well construction and well maintenance activities as well as memory reliant subsurface data gathering. Slickline work includes mechanical services such a gauge emplacement and recovery, subsurface valve manipulation, well bore cleaning and fishing.

Braided line has mechanical characteristics similar to mono-conductor wireline, and is used for well construction and maintenance tasks such as heavy duty fishing and well bore cleaning work.