Slickline

Slickline refers to a single strand wire which is used to run a variety of tools down into the wellbore for several purposes.

In use and appearance it is connected by a drum as it is spooled off the back of the slickline truck to the wireline sheave, a round wheel grooved and sized to accept a specified line and positioned to redirect the line to another sheave that will allow the slickline to enter the wellbore.

The wireline operator monitors at surface the slickline tension via a weight indicator gauge and the depth via a depth counter 'zeroed' from surface, lowers the downhole tool to the proper depth, completes the job by manipulating the downhole tool mechanically, checks to make sure it worked if possible, and pulls the tool back out by winding the slickline back onto the drum it was spooled from.

This probably changed because the flat measuring line wasn't as strong as the modern slickline, and separate depth counters were developed.

It is advantageous to keep the diameter of the wire as small as possible for the following reasons: The disadvantage of a smaller-diameter slickline is the lower strength.

Mechanical jars look like a long, tubular piece of machined metal that slides longer or shorter approximately 75% to 90% of its total length.

The reason for the initial tighter restriction is to allow the operator to pull his line to the desired hitting range.

Jars are commonly used to shear small brass or steel pins that are put in place to function certain down-hole tools at a certain moment.

These are tools designed for fishing other wireline components which have been dropped or placed in the well down hole.

A gauge cutter is a tool with a round, open-ended bottom which is milled to an accurate size.

Large openings above the bottom of the tool allow for fluid bypass while running in the hole.

If an obstruction is found downhole, a lead impression block can be run to help determine its nature.

They are also sometimes called "confusion" blocks because they only give a two-dimensional view of the down-hole object, making it hard for an inexperienced person to determine what three-dimensional object is in the hole Bailers are downhole tools that are generally long and tubular shaped, and are used for both getting samples of downhole solids (sand, scale, asphaltenes, rust, rubber and debris from well servicing operations) and for 'bailing' the unwanted downhole solids from the well.

A sample bailer is a hollow tube (the barrel), generally around a meter long, around 40 mm in diameter, with a 'ball check' – a form of non-return valve – on the bottom and an opening at the top.

The success of this depends on how readily the solid was accepted into the barrel, and if the ball check was properly seated on the return trip to surface.

A stroke bailer functions like a 'Chinese water pump', and is used to collect unwanted solids from the wellbore.

Ideally, this draws the downhole solid in through the bottom 'shoe' of the tool, past the check and into the barrel for collection.

Sometimes fluid will be added to the wellbore to assist in bailing by bringing up the pressure, and also lubricating the downhole solid.

Care must be taken when disassembling at surface as the tool is potentially charged with the downhole pressure (possibly many tens of thousands of kpa) and may 'blow apart' when being unthreaded if not bled off first.

The 'locking tool', or 'lock' for short, can be attached via threaded connection to the top of a variety of different tools, including but not limited to, downhole chokes (flow rate restrictors sized according to a pre-determined calculation), one-way check valves (TKX style plugs), instrument hangers, and most commonly, tubing plugs.

The lock is fitted onto the running tool and attached using shear pins made of brass or steel.