Slickline

Slickline is a term for a tool of conveyance used generally in oil and gas well servicing. Slickline looks like a long, smooth, unbraided wire, often shiny, silver/chrome in appearance. It comes in varying lengths, according to the depth of wells in the area it is used (it can be ordered to specification) up to 30,000 feet in length. Slickline is spooled onto a hydraulically controlled drum in the back of a wireline truck. The wireline truck is driven out to the wellsite, and specialized equipment designed to keep high pressure and well fluids contained, while allowing the slickline to run deep down the hole of the oil/gas well is 'rigged up'. Downhole tools, which are long, and tubular shaped, with various mechanisms on them, are lowered via the slickline to the appropriate depth, whereupon they carry out their tasks. The operator of the wireline truck controls the drum at surface, monitoring the depth which is measured from a surface point, and the weight, which informs the operator via a sensitive gauge attached to the wire what is happening downhole. Upon completion of that step of the job, they are pulled back to surface via the slickline, which generally stays attached to the 'toolstring'. Slickline comes in different grades, meant to maintain a balance between being strong enough to support the weight of itself, the toolstring, and restrictions encountered downhole without breaking, and also corrosive and dangerous gases and fluids that occur in oil and gas wells. Shiny slickline (ie: 316 Stainless Steel, GD 31 Molybdenum), depending on the metalurgy, is generally used for more corrosive wells, or wells with H2S poisonous gas, or CO2, which can drastically affect metal performance. Dark grey slickline (ie: plow steel), which has the colour of a new, grey nail, but which rusts easily, generally has a higher strength than the more exotic metalurgies of the same diameter; however, it is more adversely affected by bad well conditions and therefore is usually only used in 'sweet' wells. As well depths have increased over the years since the first measuring lines were brought into use, accompanied by increased working loads, it has become necessary to develop wireline having a high strength/weight ratio. This is known as slickline. There is a need for strength to accomplish the operation without the wire breaking, and a need to keep the diameter of the wire as small as possible for the following reasons:

It reduces the load of its own weight

It can be run over smaller diameter sheaves, and wound on smaller diameter spools or reels without overstressing by bending

It keeps the reel drum size to a minimum

It provides a small cross-section area for operation under pressure

The sizes of solid wireline in most common uses are: 0.108ins and 0.125ins diameter, and are obtainable from the drawing mills in one-piece standard lengths of 18,000, 20,000, 25,000 and 30,000 ft.

Uses

Slickline tools operate with a mechanical action, controlled from surface in the wireline trucks operators compartment. Typically, this mechanical action is accomplished by the operation of jars. There are generally two types of jars, mechanical and hydraulic. Mechanical jars look like a long, tubular piece of machined metal that slides longer or shorter approximately 75% to 90% of its total length. They give the effect of hammering on the downhole tools. The weight or hit of the 'hammer' depends on how much sinker bar is added above the jars. Generally, a slickline operator controls the downhole tools with taps and hits from the sinker bar via the mechanical jars, controlled at surface by lowering or raising the toolstring and monitoring weight, depth, and pressure. Mechanical jars for slickline can hit up or down the hole, making them a versatile form of jarring. Hydraulic jars for slickline are generally meant to jar up only, because not enough sinker bar is able to feasibley lubricated in to jar down on the downhole tools. Hydraulic jars work by the operator pulling up on the line, which puts an upward force on the top of the hydraulic jars. The bottom of the hydraulic jars is usually attached by threaded connection to the mechanical jars, which are attached to the downhole tools. Depending on how hard the operator pulls on the hydraulic jars will affect how fast they hit, and how hard they hit. when the top is pulled on, the inner mandrel begins to slide upwards. It has a restriction on it, that hydraulic fluid has to bypass as it is pulled upwards, until it reaches an area of no restriction, allowing it to slide rapidly. The reason for the initial tighter restriction is to allow the operator to pull his line to the desired hitting range. Generally once he hits that range on his weight indicator, he waits while the jars open to the less restricted point, whereupon the sinker bar travels upwards rapidly, providing an upwards hit on the downhole tools. The jars can then be 'reset' by lowering the line until the weight of the sinker bar closes, or pushes the inner mandrel of the hydraulic jars back to the starting position. Because the hydraulic jars are designed to provide a wait time to allow the operator to get up to the desired line tension, they can provide a very effective upwards hit. Mechanical jar and hydraulic jar hitting power is affected by the length of the jars (the longer the length, they faster they can travel before they stop), the mass of the weight above them (the more the mass, the harder they will hit), and the tension of the line pulling on them. Some completion components may be deployed and retrieved on slickline such as wireline retrievable safety valves, battery powered downhole gauges, perforating, setting explosively set bridge plugs, and setting or retrieving gas lift valves. Slickline can also be used for fishing, the process of trying to retrieve other equipment and wire, which has been dropped down the hole.

The most common applications for slickline are:

Tagging T.D. (which is the furthest depth possible down the wellbore)
Gauge Ring runs (which is running a special sized downhole tool called a gauge ring, which comes in various pre-machined diameters, designed to ensure the pipe is clear to a certain point)
Broach tubing / Plunger Installations (a tubing broach looks like an aggressive, tubular file, available in different diameters, used for removing burrs and crimps in the inside of tubing and casing in oil and gas wells)
Bailing sand and debris (removing formation sand/rock and other such debris left over from the drilling and completion of the well, using a specialized tool called a bailer. This tool uses either a chinese water pump type stroke action or a hydrostatic vacumn action to suction up the downhole debris, allowing it to be conveyed back to surface via the wireline)
Shifting sleeves (formations downhole can be isolated behind sliding metal 'windows' called sliding sleeves. They are shifted open or closed by means of a specialized shifting tool locating the sleeve and it being jarred up or down, providing access or closing off that formation or section of casing)
Setting / Pulling plugs and chokes (specialized downhole tools which either lock into pre-machined restrictions in the tubing, or which lock into the tubing itself, sealing pressure from below or above the plug)
Setting / Pulling gas lift valves
Running tailpipes (tubing extensions where the tubing is not landed close enough to the formation perforations in the casing)
Bottom hole pressure and temperature surveys (specialized electronic and mechanical tools designed to measure the pressure and temperature at predetermined depths in the wellbore. This data can be used to determine reservoir life)
Spinner Surveys (to determine which formation perforations have the best inflow / which perforations make the most water / liquids)
Kinley perforator, sandline cutter, and caliper
Running production logging tools
Fishing operations (fishing usually refers to attempting to retrieve lost tools or wire, or other debris that was not intended to restrict the flow / disrupt the well operations. Fishing can be difficult, due the fish being downhole, and other affecting conditons such as high pressure, the fish being jammed in the tubing / casing)
Paraffin cutting (making a hole through and removing a wax buildup, which is a byproduct of oil cooling too much to reach surface)
Chipping ice / salt (restrictions and plugs which can be formed as by products of a flowing well)
Lubricating long assemblies in and out of the hole (lubricating is done via a larger than tool overall diameter pipe, joined at surface on top of the wellhead, which houses the valve that shuts the pressure in downhole. The lubricator should be long enough to be able to swallow the toolstring and downhole tools that are to be run or pulled)

Braided line

Braided line is generally used when the strength of slickline is insufficient for the task. Most commonly, this is for heavy fishing such as retrieving broken drill pipe. The most common use for braided line is fishing electric line tools.

Slickline Tools

Jar

This type of tool can extend and be closed rapidly to induce a mechanical shock to the tool string. This shock can induce certain components such as plugs to lock into place and then unlock for retrieving. Spang jars are manually operated by the wireline operator who either lifts or lowers wire rapidly, requiring a great deal of expertise. Power jars use springs or built-in hydraulics to give an upward jarring motion where greater force is required.

Stem

Stem essentially just serves to add weight to the toolstring. The weight may be necessary to overcome the pressure of the well. Some variations of stem, called roller stem, may have wheels built into the tool to allow the tool string to glide more easily down moderately deviated wells.

Pulling tools

These are tools designed for fishing other wireline components which have been dropped down hole. All wireline tools are designed with 'fishing necks' on their top side, intended to be easily grabbed by pulling tools. Pulling tools are also used for retrieving seated components such as plugs.

Gauge cutter

The important part of these tools is their bottom end, which is a sharp metal ring of accurately determined size. By allowing for a sharp up and down motion, the metal ring can cut through contamination such as scale which may build up in the well bore. Gauge Cutters or Gauge Rings are used to determine the I.D. of the tubing or to locate seating nipples or tight spots in the tubing. Gauge rings are generally run prior to running plugs and other tools to ensure that they will fit in the tubing.

Lead impression block

If an obstruction is found downhole, a lead impression block can be run to help determine its nature. The LIB has a malleable lead base in which the obstruction can leave an impression when they meet. The LIB is called Wireline Camera because of its function to mark any object downhole. They are also sometimes called "confusion" blocks because they only give a two-dimensional view of the down-hole object, making it hard to determine what three-dimensional object is in the hole.

Bailer

This tool is designed to collect samples of downhole solids for the purposes of cleaning out or just determining the nature of solids such as scale.

Running Tools

These tools are used to set plugs into nipples located in the tubing. The plug is fitted onto the running tool using shear pins made of brass or steel. When the target nipple is reached the plug can be set by shearing these pins using jars.there are a many running tools such us : for valves GA2 JK2 RK for lock mondrels Running tool type R X