Meaning of wireline
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 petro physical and geophysical data and the delivery of well construction services such as pipe recovery, perforating, plug setting and well cleaning and fishing.
Wireline logging services employ an electrical cable to lower tools into the borehole to perform the continuous recording of the reservoir characteristics.
Wireline logging services are provided by oilfield service companies such as Halliburton (U.S.) to oil and gas companies such as Royal Dutch Shell (The Netherlands). These are frequently used during all the lifecycle stages of a well including exploration, drilling, completion, production, intervention, and others.
The wireline logging services market
The wireline logging services market is highest in North America, where many leading oil field service companies operate including Schlumberger (U.S.), Halliburton (U.S.), Baker Hughes (U.S.), and other medium and small players. While the North American wireline services market is reaching its maturity, the other geographic regions are exhibiting a decent growth rate, owing to the new development of hydrocarbon reserves.
The growing demand for energy with increasing financial investments in offshore and unconventional exploration and production activities is expected to drive the global wireline logging services market.
There are four basic types of wireline
- single conductor
- braided line.
Other types of wireline include sheathed slickline and fiber-optic lines.
Multi-conductor– 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.
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″ to 5/16″ 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.
Slickline– Slickline is a smooth single strand of wireline with diameters ranging from 0.082″ to 1.25″. 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.
Braided line– 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 wellbore cleaning work.
Wireline tools are specially designed instruments lowered into a wellbore on the end of the wireline cable. 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. Modern wireline tools can be extremely complicated and are often engineered to withstand very harsh conditions such as those found in much modern oil, gas, and geothermal wells.
- Natural gamma-ray tools
- Nuclear tools
- Resistivity tools
- Sonic and ultrasonic tools
- Nuclear magnetic resonance tools
- Borehole seismic tools
For oilfield work, the wireline resides on the surface, wound around a large (3 to 10 feet in diameter) spool. Operators may use a portable spool (on the back of a special truck) or a permanent part of the drilling rig. A motor and drive train turn the spool and raise and lower the equipment into and out of the well – the winch.
Controlling of pressure during the wireline operation
The pressure control employed during wireline operations is intended to contain pressure originating from the wellbore. During open hole electric line operations, the pressure might be the result of a well kicking. During the cased hole electric line, this is most likely the result of a well producing at high pressures.
The Controlling of pressure during the wireline operation is done with the help of the following ways:
- Wireline valve
- Pump-in sub
- Grease injector
- Line wiper
- Quick test sub
The wireline logging services market has great opportunities outside North America; however, its growth depends upon many reasons that include environmental objections and a subsequent ban on certain logging techniques in few countries, which are key hurdles for the growth of this market.