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.

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.

Slickline work includes mechanical services such a gauge emplacement and recovery, subsurface valve manipulation, well bore cleaning and fishing.

Used to place and recover wellbore equipment, such as plugs, gauges and valves, slicklines are single-strand non-electric cables lowered into oil and gas wells from the surface.

Braided line can contain an inner core of insulated wires which provide power to equipment located at the end of the cable, normally referred to as electric line, and provides a pathway for electrical telemetry for communication between the surface and equipment at the end of the cable.

First developed by Conrad and Marcel Schlumberger in 1927, wireline logs measure formation properties in a well through electrical lines of wire.

The measurements are made by initially lowering sonde using the wireline to the prescribed depth and then recorded while raising it out of the well.

When producing wells require remedial work to sustain, restore or enhance production, this is called workover.

Workover operations conducted can include well clean-up, setting plugs, production logging and perforation through explosives.

They are individually designed to provide any number of particular services, such as evaluation of the rock properties, the location of casing collars, formation pressures, information regarding the pore size or fluid identification and sample recovery.

The tools have a radiation sensor, which is usually a scintillation crystal that emits a light pulse proportional to the strength of the gamma ray striking it.

From the photomultiplier tube, the current pulse goes to the tool's electronics for further processing and ultimately to the surface system for recording.

Any pore spaces in the rock are filled with fluid containing hydrogen atoms, which slow the neutrons down to an epithermal or thermal state.

This atomic interaction creates gamma rays which are then measured in the tool through dedicated detectors, and interpreted through a calibration to a porosity.

Modern density tools utilize a Cs-137 radioactive source to generate gamma rays which interact with the rock strata.

The signal path leaves the transmitter, passes through the mud column, travels along the borehole wall and is collected at multiple receivers spaced out along the tool body.

Different types of pressure waves can be generated in specific axis, allowing geoscientists to determine anisotropic stress regimes.

This is very important in determining hole stability and aids drilling engineers in planning for future well design.

This is especially useful for determining small scale bedding and formation dip, as well as identifying drilling artifacts such as spiraling or induced fractures.

Second, the hydrogen atoms are tipped by a short burst from an oscillating magnetic field that is designed so that they precess in resonance in a plane perpendicular to B0.

Channeling is where large, contiguous voids in the cement sheath form, typically caused by poor centralization of the casing.

A CBT makes its measurements by rapidly pulsing out compressional waves across the well bore and into the pipe, cement, and formation.

As the CCL passes by a casing joint, or collar, the difference in metal thickness across the two magnets induces a current spike in the coil.

Setting tools typically use the expanding gas energy from a slow-burning explosive charge to drive a hydraulic piston assembly.

Most completion packers or plugs have a specially designed shear mechanism that release the setting tool from the element allowing it to be retrieved back to surface.

The original design and concept of the tool was to stop surface casing pressure without impacting production by leaving hardware in the well bore.

Cable heads are typically custom built by the wireline operator for every job and depend greatly on depth, pressure and the type of wellbore fluid.

Current models use optical encoders to derive the revolutions of a wheel with a known circumference, which in turn is used to figure speed and depth.

During wireline operations, a steel ball sits to the side of a confined area within the grease head while the cable runs in and out of the hole.

This device is normally located just above the well control valves, providing protection to these important barriers from a dropped tool.